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*For correspondence. (e-mail: raghuram98@https://www.doczj.com/doc/fc10126058.html,) Molecular physiology of plant nitrogen use efficiency and biotechnological options for its enhancement
Ravi Ramesh Pathak 1, Altaf Ahmad 2, Sunila Lochab 1 and Nandula Raghuram 1,*
1School of Biotechnology, Guru Gobind Singh Indraprastha University, Kashmiri Gate, Delhi 110 403, India 2
Department of Botany, Jamia Hamdard, New Delhi 110 062, India
Nitrogen use efficiency (NUE) in plants is a complex phenomenon that depends on a number of internal and external factors, which include soil nitrogen availabi-lity, its uptake and assimilation, photosynthetic carbon and reductant supply, carbon–nitrogen flux, nitrate signalling and regulation by light and hormones, to name a few. The molecular basis for organism-wide regulation of nitrate assimilation is not yet fully un-derstood, and biotechnological interventions to im-prove crop NUE have met with limited success so far. This article summarizes the physiological, biochemical and molecular aspects of NUE, QTL mapping studies as well as transgenic efforts to improve it in crop plants and model plants. It encompasses primary and secondary N-assimilatory pathways and their inter-play with carbon metabolism, as well as signalling and regulatory components outside the metabolic cascade. The article highlights the need for an integrated ap-proach combining fertilizer management techniques with biotechnological interventions to improve N flux and NUE for Indian crop cultivars.
Keywords: Biotechnological interventions, molecular physiology, nitrogen flux, nitrogen use efficiency.
N ITROGEN (N) is one of the most critical inputs that de-fine crop productivity and yield under field conditions, and must be supplemented to meet the food production demands of an ever-increasing population. Efficient utili-zation of fertilizer N is essential to ensure better value for investment as well as to minimize the adverse impacts of the accumulation of reactive N species in the environ-ment. The current average nitrogen use efficiency (NUE) in the field 1 is approximately 33% and a substantial pro-portion of the remaining 67% is lost into the environ-ment, especially in the intensively cropped areas 2. This concern was reflected in the recent Nanjing Declaration of the International Nitrogen Initiative (http://www. https://www.doczj.com/doc/fc10126058.html,/nanjing_declaration.0.html ), which called for immediate development of a comprehensive approach to optimize N management in every sphere of life.
Though the form and amount of N available to the plant can be improved by managing fertilizer–soil–water–air interactions, the innate efficiency of the plant to util-ize this available N has to be tackled biologically. The biological processes involved include nitrogen uptake, translocation and assimilation, and their optimal contribu-tion towards a desirable agricultural outcome, such as biomass growth and/or increased grain/leaf/flower/fruit/ seed output, depending on the plant/crop involved. Identi-fication of appropriate phenotypes, genotypes, molecular markers and target candidates for improvement of NUE poses a formidable challenge. The purpose of this article is to summarize the current state of our understanding of the physiological and molecular aspects of plant N re-sponse and NUE, with a brief overview of the attempts made so far towards manipulating it and the possible op-tions and strategies for future interventions.
Concept and definition of NUE
As a concept, NUE includes N uptake, utilization or ac-quisition efficiency, expressed as a ratio of output (total plant N, grain N, biomass yield, grain yield) and input (total N, soil N or N-fertilizer applied). NUE is quantified based on apparent nitrogen recovery using physiological and agronomic parameters 3. Agronomic efficiency is an integrative index of total economic outputs relative to the available soil N (native and applied). Apparent nitrogen recovery is related to the efficiency of N uptake; physio-logical NUE deals with N utilization to produce grain or total plant dry matter. The most suitable way to estimate NUE depends on the crop, its harvest product and the processes involved in it.
Molecular physiology of nitrogen uptake and assimilation
Among the various forms of N available to the plant,
nitrate (NO –
3) is the most preferred source for most plants. It is taken up by active transport through the roots, dis-tributed through the xylem and assimilated by the sequen-tial action of the enzymes nitrate reductase (NR) and
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nitrite reductase (NiR). The end-product, ammonium (NH+4), is incorporated into amino acids via the glutamine syn-thetase (GS) and glutamate synthase (GOGAT) cycle4. The availability of organic acids is critical for the supply of carbon skeletons needed for amino acid synthesis, which in turn demands optimum partitioning of photosynthetic sugars and the coordinated operation of multiple metabolic and regulatory pathways.
Nitrate uptake
Optimum uptake of nitrate is the first step to enhance N use in any plant. It has been established from a number of physiological studies that plants acquire their nitrate from the soil through the combined activities of a set of high- and low-affinity transporter systems5, with the influx of NO–3 being driven by the H+ gradient across the plasma membrane. Some of these transporters are constitutively expressed, while others are nitrate-inducible and subject to negative feedback regulation by the products of nitrate assimilation. The low affinity transport system (LATS) is used preferentially at high external nitrate concentrations above 1 mM, while the high affinity transport system (HATS) works at low concentrations (1 μM–1 mM). LATS is constitutive in nature and possibly has a signalling role to induce the expression of HATS and nitrate assimilatory genes, presumably playing a nutritional role only above a certain threshold. The identification of two gene families, NRT1 and NRT2, on the basis of their deduced amino acid sequences5 has contributed towards unravelling the mechanisms of nitrate uptake in higher plants. Physiology of nitrate reduction in crops
A portion of the nitrate taken up is utilized/stored in the root cells, while the rest is transported to other parts of the plant. Due to the abundant availability of photosynthetic reductants, leaf mesophyll cells are the main sites of nitrate reduction. This is initiated by the NAD/NADP-dependent NR enzyme, which catalyses the two-electron reduction of nitrate to nitrite in the cytosol. Nitrite is transported into the chloroplast, where it is further reduced into am-monium ion by a ferredoxin-dependent NiR. Being the first, irreversible and often rate-determining step of the N-assimilatory pathway, nitrate reduction has been a favourite step for physiological and biochemical appro-aches to optimize fertilizer N use (Table 1). The trans-genic approaches have been dealt with separately later in the article.
Pattern of NR activity
NR activity in leaf blades, expressed either as seasonal average or converted into seasonal input of reduced N, has been related to total reduced N, grain N and grain yield of cereals6. The pattern of nitrate assimilation from different plant parts, viz. the main shoot of wheat7, de-veloping ear of wheat plants grown at different soil N levels8 and in the leaf blades at different stages of growth9 has revealed a direct positive correlation between increas-ing NR activity and increasing rates of nitrogenous fertili-zation. Most plant tissues have the capacity to assimilate nitrate, though their NR activity varies widely9–12. Analysis of the shoot components revealed that leaf blades are the main sites in cereals like wheat8, corn13 and barley10. Detectable level of NR activity has also been observed in the developing ear components of wheat, bar-ley and pod covers of chickpea14. Among the ear compo-nents, the in vivo activity was highest in awns. It was also observed that the ontogenetical pattern of NR activity corresponds to the nitrate content, with which it is sig-nificantly correlated15. The light/dark conditions also affect NR activity; heterotrophic nitrate assimilation in darkness is closely linked to the oxidative pentose phosphate pathway and the supply of glucose-6-phosphate. Under photoautotrophic conditions, glucose-6-phosphate dehy-drogenase is inhibited by reduction with thioredoxin in light, thus replacing the heterotrophic dark nitrate assimi-latory pathway with regulatory reactions functioning in light16. These studies as well as bioenergetic calcula-tions17 have indicated that both yield and N harvest or protein can be increased to some extent with adequate nitrogen supply by altered management practices, thus improving the fertilizer NUE.
Genotypic differences in NR activity
Genotypic differences in the NR levels have been re-ported in corn, wheat, sorghum and barley. In sorghum, a positive relationship between decline in the height of the plant and enhancement of NR activity was observed18, though no such relationship was evident in tall and dwarf cultivars of wheat, T. aestivum19. Wheat genotypes re-vealed over twofold variability in NR activity20, which supports genetic findings that the enzyme level is highly heritable, its differences are reflected in N harvest and that hybrids could be bred with predictable NR levels by se-lecting parents appropriately. In the high NR genotypes, higher levels of NR activity were found under low N lev-els, often with significantly higher N concentration in the grains21. They also have sustained activity at later stages of growth, such as flag leaf emergence and anthesis20. The reasons for these genetic differences are not fully understood, except that the regulation operated at the level of gene expression16 and that low levels of NADH might limit NR activity in low NR genotypes22. Ammonium assimilation
Ammonium is taken up directly through the roots, though uptake can also occur in a biphasic manner, involving
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Table 1. Transgenic studies on N transport, primary and secondary N assimilating genes
Gene product and gene source Promoter Target plant Phenotype observed
Nrt1.1 – High affinity nitrate transporter (Arabidopsis )
CaMV 35S Arabidopsis Increase in constitutive nitrate uptake but not in induced 57 Nrt2.1 – High affinity nitrate transporter (N. plumbaginifolia ) CaMV 35S, rol D
N. tabacum Increased nitrate influx under low N conditions 58
N. plumbaginifolia CaMV 35S N. tabacum 3–4 fold drop in NR protein and activity, no change in NR transcript 92
NR – Nitrate
reductase
N. plumbaginifolia CaMV 35S N. tabacum Increased NR activity, biomass, drought stress 61 N. tabacum CaMV 35S L. sativa Reduced nitrate content, chlorate sensitivity 93 Nia – Nitrate
reductase N. tabacum CaMV 35S N. plumbaginifolia Nitrite accumulation in high nitrate supply 94 Nia2 – Nitrate N. tabacum reductase
CaMV 35S S. tuberosum Reduced nitrate levels 60
N. tabacum CaMV 35S N. plumbaginifolia, Arabidopsis NiR activity, no phenotypic difference 62
NiR – Nitrite
reductase
S. oleracea CaMV 35S Arabidopsis
Higher NiR activity, higher nitrite accumulation 63 O. sativa CaMV
35S N. tabacum Improved photorespiration capacity, and increased resistance to photo-oxidation 64
O. sativa CaMV 35S O. sativa Enhanced photorespiration, salt tolerance 65 GS2 – Chloroplastic glutamine
synthetase
N. tabacum Rubisco small subunit
N. tabacum
Enhanced growth rate 67
Fd-GOGAT – Fd dependent glutamate synthase (N. tabacum )
CaMV 35S N. tabacum Diurnal changes in NH 3 assimilation 66 G. max CaMV 35S L. corniculatus Accelerated senescence 70 G. max rol D L. japonicus Decrease in biomass 71
P. vulgaris Rubisco small unit
T. aestivum Enhanced capacity to accumulate nitrogen 72
M. sativa CaMV 35S N. tabacum Enhanced growth under N starvation 69 G. max CaMV 35S M. sativa No increase in GS activity 73
Pea CaMV 35S N. tabacum Enhanced growth, leaf-soluble protein, ammonia levels 95 P. sylvestris CaMV 35S Hybrid poplar Enhanced growth rate, leaf chlorophyll, total soluble protein 74
G. max CaMV 35S P. sativum No change in whole plant N 75
GS1 – Cytosolic
glutamine
synthetase
Alfalfa CaMV 35S L. japonicus Higher biomass and leaf proreins 96
O. sativa O. sativa O. sativa Enhanced grain filling, increased grain weight 79 NADH-GOGAT–
NADH-dependent glutamate synthase
M. sativa CaMV 35S N. tabacum Higher total C and N content, increased dry weight 67 E. coli CaMV 35S N. tabacum Increased biomass and dry weight 97
E. coli CaMV
35S N. tabacum Increased ammonium assimilation and sugar content 98 GDH – Glutamate dehydrogenase L. esculentum CaMV 35S L. esculentum Twice GDH activity, higher mRNA levels and twice glutamate concentration 99 ASN1 – Glutamine dependent asparagine synthetase (A. thaliana )
CaMV 35S A. thaliana
Enhanced seed protein 86
ASNI – Asparagine synthetase (P. sativum ) CaMV 35S N. tabacum Reduced biomass and increased level of free asparagine 85 Asp AT – Mitochondrial aspartate aminotransferase (prosomillet)
CaMV 35S N. tabacum Increased AspAT, PEPCase activity 100 AlaAT – Alanine aminotransferase (barley) btg26 Brassica napus Good yields even with 50% less N fertilizer 101 ANR1 – MADS transcription factor (Arabidopsis )
CaMV 35S Arabidopsis Lateral root induction and elongation 81
GLB1 – PII regulatory protein (Arabidopsis ) CaMV 35S Arabidopsis Growth rate, increased anthocyanin production in low N 89 Dof1 – Transcription factor (Zea mays ) 35S C4PDK Arabidopsis
Enhanced growth rate under N limited conditions, increase in amino acid content 80
LATS and HATS 23. Ammonium generated from primary nitrate assimilation, re-assimilation of internal metabo-lites or other secondary sources, is incorporated into amino acids in a reaction catalysed by GS and then by GOGAT 24. GS is the central enzyme in ammonium assimilation in plants with a cytosolic (GS1) and a plastidic (GS2) iso-form. Similarly, GOGAT has two isoforms, a ferredoxin-dependent plastidic isoform (Fd-GOGAT) and a NADH-dependent cytosolic isoform (NADH-GOGAT). The plas-tidic isoforms of both the enzymes (GS2 and Fd-GOGAT)24 are involved in primary ammonia assimilation, while
their cytosolic isoforms are involved in secondary assimi-lation.
Secondary ammonium assimilation/remobilization
As nitrogen is a major limiting factor for plant growth, the efficient re-assimilation of metabolically generated ammonium is highly important for NUE, plant perform-ance and to prevent loss of ammonia to the atmosphere. Cytosolic GS1 and NADH-GOGAT are of critical impor-tance in this regard. GS1 has been proposed as a key
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component of NUE in plants24 and its metabolic role is particularly important for nitrogen remobilization and re-cycling in woody plants25,26. Ammonium ions are also derived from the mitochondrial glycine decarboxylase re-action, which is an integral part of the photorespiratory carbon and nitrogen pathways. The importance of gluta-mate dehydrogenase (GDH) in higher plant N metabolism is still controversial, as it has never been clearly demon-strated that it plays a significant role either in ammonium assimilation or carbon recycling in plants. The role of GDH in N management and recycling has been recently reviewed in a number of whole-plant physiological stud-ies performed on tobacco27 and maize28.
Signalling and regulation of nitrogen assimilation
Since N demand and its actual availability tend to vary in time, space and environmental conditions, the regulation of plant-N metabolism must be responsive to nutritional, metabolic and environmental cues. The following sec-tions deal with the recent advances in our knowledge of the complex web of interactions in the regulation of ni-trate assimilation by internal and external signals and its coordination with the overall metabolism of the plant. Role of nitrate
Nitrate is not only a nutrient but also a signal for the regulation of hundreds of nitrate-responsive genes, which include N and C metabolizing enzymes, redox enzymes and a whole range of signalling proteins and transcription factors. However, the mechanism of nitrate signalling is not well understood, though calcium and protein kinases have been implicated, as reviewed reccently29. The tran-scriptional regulation of nitrate responsive genes could involve cis-acting regulatory sequences or nitrate response elements (NRE)29. Our recent genome-wide computa-tional analysis of a previously reported NRE comprising the consensus sequence [(a/t)7Ac/gTCA] based on NR and NiR turned out to be neither unique nor common to all ni-trate responsive genes in Arabidopsis and rice, necessitat-ing a fresh search for newer candidate NRE sequences30. However, the identification of putative cis elements that are responsive to C/N signalling interactions indicates the possible combinatorial role of different cis-regulatory elements31. Identification of such regulatory elements might provide an end-point for nitrate signalling and open up avenues for characterizing/manipulating the rest of the signalling pathway to enhance NUE.
Role of light
Light is an additional signal that regulates the expression of many nitrate responsive genes32,33. Light regulation of NR expression and activity operates differently in green plants and etiolated seedlings, and is mediated by differ-ent photoreceptors. The effects of light in green plants are probably mediated more indirectly through photosynthe-sis and sugars33. Using pharmacological approaches, the phytochrome-mediated regulation of NR gene expression in etiolated maize seedlings was suggested to be mediated through G-protein, PI cycle and protein kinase C (refs 34, 35). Similar effects of cholera toxin and lithium ions were also found recently on NR-mRNA and activity in light-grown–dark-adapted rice seedlings, but both PMA and okadaic acid had inhibitory effects on NR-mRNA and activity, indicating different responses in maize and rice, either due to etiolated/green plant or C3/C4 differences36. Role of 14-3-3 proteins
It is becoming increasingly evident that 14-3-3 proteins play a crucial role in bringing about metabolic coordina-tion between enzymes of C and N metabolism, modulat-ing their activity by binding them in a phosphorylation-dependent manner. NR, GS, sucrose-phosphate synthase (SPS), trehalose-phosphate synthase, glutamyl-tRNA syn-thetase, and an enzyme of folate metabolism have been found to bind to 14-3-3s in a phosphorylation-dependent manner37. Experiments in transgenic potato plants indi-cate that repression of 14-3-3 proteins led to significant increases in NR and SPS activities38. More recently, the effect of repression of 14-3-3 genes on actual activity of NR in Nicotiana benthamiana leaves, was studied by si-lencing the Nb14-3-3a and Nb14-3-3b genes using virus-induced gene silencing method, which implicated Nb14-3-3a and/or Nb14-3-3b proteins in the inactivation of NR activity under darkness in N. benthamiana39. The 14-3-3 proteins also interact with components of plant signalling pathways as observed in their interaction with RGS3, a negative regulator of the G-alpha subunits of heterotrimeric G proteins40, suggesting a possible role in the regulation of G-protein signalling pathways, which in turn have been implicated in mediating light regulation of NR34. Role of downstream N metabolites
Nitrite accumulation is toxic to the plant and is also in-hibitory to nitrate induction, whereas the effects of am-monium and glutamine vary depending on the tissue and plant type as well as conditions of the study41,42. The addi-tion of ammonium or nitrate to N-limited whole plants or plant cells induces (at the transcript and/or activity level) enzymes of glycolysis and the Krebs cycle, which are re-quired for the synthesis of 2-OG43. Glutamate and 2-oxoglutarate have recently been shown to stimulate ni-trate induction of NR and NiR in rice seedlings42. The role of glutamate as a signalling molecule in plant nitrogen metabolism has been reviewed recently24, indicating that
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the manipulation of N nutrition leads to dynamic altera-tions in plant respiratory metabolism in response to changes in cellular energetic demands. Therefore, the roles and in-teractions of downstream N metabolites may have to be factored into strategies for optimizing N response and NUE.
Role of hormones
Plant hormones like cytokinin have been shown to mimic the N-dependent regulation of gene expression in photo-synthesis, cell cycling and translational machinery44; hint-ing at a possible role in communicating the availability of nitrogen from roots to leaves45. Additionally, N sensing and response also seem to be affected by the crosstalk between various plant hormones. Auxin synergistically affects cytokinin activity on cell division and organo-genesis46, while ABA antagonizes the cytokinin-mediated nitrogen signalling by negatively regulating cytokinin-inducible response regulator genes. Unlike cytokinins, which are positively regulated by nitrate, ABA biosynthesis is down regulated by nitrogen sufficiency47. Although gibberellins do not seem to play any role in the control of nitrate assimilation, at least in the vegetative stages of Arabidopsis48, benzyladenine in combination with nitrate was shown to enhance NR-specific mRNA21. Despite these findings, establishing the role of hormones in nitrogen signalling needs further characterization of the complete signalling pathway.
Interaction of nitrogen and carbon metabolism
The tight regulation of C/N metabolism has been revealed through numerous studies, which have indicated that the net photosynthesis rate and amount of photosynthetic components are correlated with the leaf-N content. The relative abundance of N pools in the plant plays a signifi-cant role in regulating the C/N metabolism49. Nitrate sup-ply has been shown to result in the decrease of starch synthesis and diversion of carbon towards the conversion of organic acids into amino acids43. On the other hand, nitrate deficiency results in the decrease of many amino and organic acids, along with an increase in the level of several carbohydrates, phosphoesters and a handful of secondary metabolites50. Recent studies on global gene expression have revealed that a significant number of the previously reported nitrate responsive genes actually re-quired the presence of both nitrogen and sugar, suggest-ing significant interaction between C and N metabolites in regulating gene expression, with carbon modulating the effects of nitrogen and vice versa51. Recent evidences of post-transcriptional control of C/N regulation by microRNAs have revealed globally coordinated regula- tion of specific sets of molecular machines in the plant cell52.
Given the strong relationship between N and photosyn-thetic rates, plants maximize photosynthesis by optimiz-ing partioning of N, which further depends on other environmental factors such as irradiance, nutrients, CO2 concentration, etc. Consequently, the photosynthetic ni-trogen use efficiency (PNUE) is determined by the rate of carbon assimilation per unit leaf nitrogen53. Plants pos-sessing C4 photosynthesis have a greater PNUE than C3 plants, owing to the C4 concentrating mechanism that leads to CO2 saturation of Rubisco. Higher CO2 concen-trations both compensate for the poor affinity of Rubisco for CO2 and suppress oxygenase activity, consequently increasing the PNUE at elevated concentrations. Further evaluation of the key components of photosynthesis and interactions of C/N metabolites might offer avenues for improving N uilization by optmizing N content in accor-dance with photosynthetic demand.
Interaction of nitrogen and sulphur metabolism
The importance of sulphur as a nutrient and its manage-ment vis-à-vis other nutrients like nitrate have been re-viewed recently54. Under sulphur-deficit conditions, reduced protein synthesis is accompanied by accumulation of or-ganic and inorganic nitrogenous compounds, leading to reduced NUE55, indicating the need to achieve optimum N/S balance for improved NUE.
Options for improvement in NUE
NUE can be improved to some extent by optimizing ferti-lizer–soil–water interactions, though the biological as-pects of crop improvement form the main purpose of this article. Regardless of the approach adopted, the chal-lenges in improving NUE include optimization of N supply and demand, maximization of crop N uptake and assimi-lation, minimization of N losses and ultimately, specific improvements in the yields of biomass, leaves, fruits or grains, as the case may be. The current section deals with some of these approaches and their impact on crop NUE. Fertilizer-N application management (repeated
N fertilization in split doses)
Prevalent fertilizer management practices result in high nitrate content and NR activity in the first-formed leaf blades, which decline in the subsequently formed ones20. The pattern was paralleled by soil nitrate concentration and its total content. Incubation of excised leaf blades in a nutrient solution containing 15 mM NO–3 resulted in slight increase in the NR activity of the lower leaf blade of wheat, while the activity of the upper ones was en-hanced manifold; the level of enhancement being higher in ‘high NR’ cultivars than in ‘low NR’ cultivars20. It has
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been demonstrated successfully that application of the same amount of nitrogen fertilizer in more than two splits under field conditions clearly increases the nitrogen availa-bility at later stages of growth, exploiting the sub-optimal activity of the upper laminae in wheat20. Studies on In-dian mustard genotypes with contrasting NUE showed that plants with high N uptake efficiency (UE) and high physiological N utilization efficiency (PUE) are able to not only take up N efficiently, but also utilize N efficiently. Such plants are highly desirable because they can be grown with limited N supply for environment-friendly farming systems. Genotypes with high UE accumulated higher N content than those with low UE under limited N conditions. High PUE is essential for optimum seed yield, because these genotypes absorbed N efficiently. Although the genotype with high UE and low PUE takes up N effi-ciently from the soil, it remains unutilized in the form of non-protein-N, as UE showed significant positive correla-tion with the free amino acid pool56. Thus, development of such N-efficient genotypes, which can grow and yield well at low N levels further enhance options for better management of the applied N fertilizer.
Transgenic efforts to manipulate NUE
The speed and precision of the transgenic approach en-ables one not only to test the candidate genes considered to be critical for NUE by overexpressing them, but also to identify such genes by knock-out mutations. The follow-ing sections describe various transgenic studies involving different categories of nitrate responsive genes. Manipulation of transporters
Studies in the last decade have shown that enhancing the uptake of N by overexpressing transporters may not nece-sarily improve NUE. For example, transgenic overexpres-sion of a CHL1 cDNA (representing the constitutive HATS) driven by the cauliflower mosaic virus 35S pro-moter in a chl1 mutant, recovered the phenotype for the constitutive phase but not for the induced phase57. Simi-larly, the NO–3 contents in transgenic tobacco plants over-expressing the NpNRT2.1 gene (encoding HATS), were remarkably similar to their wild-type levels, despite an increase in the NO–3 influx58. These findings indicate that genetic manipulation of nitrate uptake may not necessar-ily lead to concomitant improvement in nitrate retention, utilization or NUE, though it remains to be seen whether different plants respond differently to the overexpression of different transporters.
Manipulation NR and NiR genes
NR has long been considered to be the rate-limiting step in nitrate assimilation. Efforts to improve NUE by mani-pulating NR and NiR genes have yielded mixed results, with transformed Nicotiana plumbaginifolia plants con-stitutively expressing NR, showing a temporarily delayed drought-induced loss in NR activity, thereby allowing more rapid recovery of N assimilation following short-term water-deficit (Table 1). At the transcriptional level, de-regulation of NR gene expression by constitutive ex-pression in transgenic plants caused a reduction in nitrate levels in tissues of tobacco59 and potato60. While factors such as NO–3 availability regulate flux through the path-way of N assimilation, the NR transformants were better equipped in terms of available NR protein, which rapidly restored N assimilation. Though no tangible effects on biomass accumulation could be attributed in the short term, under field conditions of fluctuating water avail-ability, constitutive NR expression was able to confer a physiological advantage by preventing slowly reversible losses in N-assimilation capacity61. Similarly, over-expressing NiR genes in Arabidopsis and tobacco resulted in increased NiR transcript levels but decreased enzyme activity levels, which were attributed to post-translational modifications62,63. Therefore, the utility of transgenic overexpression of NR/NiR for major improvements of NUE remains uncertain, though the possibility that dif-ferent crops respond differently cannot be ruled out yet. Manipulation of GS2 and Fd-GOGAT genes Improvement in NUE via manipulation of plastidic GS2 and Fd-GOGAT genes has met with limited success. Transgenic tobacco plants with twofold overexpression of GS2 were shown to have an improved capacity for photo-respiration and an increased tolerance to high-intensity light. On the other hand, transgenics with reduced amount of GS2 had a diminished capacity for photorespiration and were photoinhibited more severely by high-intensity light compared to control plants64. Overexpression of GS2 has also been reported in rice65 and tobacco66, with improved reassimilation of ammonia in tobacco67. Studies on barley mutants with reduced Fd-GOGAT revealed changes in various nitrogenous metabolites, decreased leaf protein, Rubisco activity and nitrate content68. While these studies hint at the potential of such transgenic attempts, most of them have been inconclusive regarding NUE so far, due to lack of physiological and agronomic data.
Manipulation of GS1 and NADH-GOGAT genes Ectopic expression of pea GS1 in tobacco leaves was suggested to provide an additional or an alternative route for the reassimilation of photorespiratory ammonium, re-sulting in an increase in the efficiency of N assimilation and enhanced plant growth69. Efforts to raise more effi-cient GS1 transgenic lines have met with varying degrees
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of success70–76, with Man et al.77 providing additional empirical evidence for enhanced nitrogen-assimilation ef-ficiency in GS1 transgenic lines. Transgenic overexpres-sion and underexpression studies to modulate the expression of NADH-GOGAT in alfalfa and rice plants78,79 have implicated the involvement of GS1 in the export of N via phloem in senescing leaves. On the other hand, in case of developing leaf blades and spikelets, NADH-GOGAT was implicated in the utilization of glutamine transported from senescing organs. Though these genes of secondary ammonia assimilation appear to be more vi-able candidates for improving NUE, the degree of success needs to be tested across crops and cropping conditions. Manipulation of signalling targets
Yanagisawa et al.80 generated transgenic Arabidopsis lines overexpressing Dof1, a maize protein that belongs to the Dof family of plant-specific transcription factors known to activate the expression of several C-metabolizing genes associated with organic acid metabolism. The trans-formants showed up to 30% higher N content, higher lev-els of amino acids, better growth under low-nitrogen conditions and higher levels of mRNAs and enzyme ac-tivities for PEP carboxylase and pyruvate kinase, without any reduction of NR, GS and GOGAT RNAs. The genes upregulated by Dof1 overexpression clearly belong to the list of known nitrate responsive genes, opening up attrac-tive possibilities of improving NUE through coordinated expression of N and C metabolizing genes. A few other attempts to manipulate signalling/regulatory proteins have been made81,without significant advantage in terms of NUE. Other attempts, such as the one to manipulate a MADS box protein that controls nitrate-induced changes in root architecture, have not been assessed for their impact on NUE81.
Manipulation of source–sink relationships and nutritional quality
Molecular manipulation of certain key enzymes of N me-tabolism provides an attractive means to enhance the nutri-tional value of plant products along with increasing the quality and quantity of seed proteins in crop plants. The enzyme asparagine synthetase (AS) catalyses asparagine, one major function of which is to transport and store ni-trogen according to the plant’s need. It can also re-allocate nitrogen during specific developmental stages and environmental changes. The efficiency of protein synthesis has been shown to be dependent on the light/ dark regulation of AS activities82, with elevation of leaf AS activities and Asn levels being used as parameters to screen for high-grain protein cultivars in maize83 and rye83. On the other hand, regulating the expression of the ASN1 gene to manipulate the relationship between Asn and seed N status might enhance nutritional quality. Stud-ies have implicated AS as one of the major controlling forces for nitrogen flux when GS is limiting in plants84, and several studies on transgenic overexpression of AS genes have revealed enhanced seed protein content and total protein content85–87. Recent genetic modification of rice and wheat using barley alanine amino transferase (AAT) gene have also yielded encouraging results, includ-ing increased biomass and seed yield compared to their wild-type counterparts. Recently, Arcadia Biosciences claimed to have improved NUE by transgenic overex-pression of AAT in canola, Arabidopsis, tobacco and rice, though their actual field performance is yet to be ascer-tained (https://www.doczj.com/doc/fc10126058.html,/nutrient.htm). In other studies, two potentially important N regulation systems of Arabidopsis, PII (ref. 88) and GCN2 (ref. 89) have been targetted; though detailed analyses of the effect of their transgenic overexpression on NUE are yet to be re-ported90.
QTL mapping to find new targets for manipulation The development of molecular markers has facilitated the evaluation of the inheritance of NUE using specific quan-titative trait loci (QTLs) that could be identified. QTLs for NUE have been identified in mapping populations of maize, rice, barley and Arabidopsis, and their association with plant N status has been reviewed recently91. In maize, studies on different genotypes or populations of recombinant inbred lines based on NUE components, chromosomal regions and putative candidate genes have hinted at some factors that might control yield and its components directly or indirectly, when the amount of N fertilizers provided to the plant is varied91.
Future perspectives
It is clearly evident that optimizing the plants NUE goes beyond the primary process of uptake and reduction of nitrate, involving a paraphernalia of events, including metabolite partitioning, secondary remobilization, C–N interactions, as well as signalling pathways and regula-tory controls outside the metabolic cascades. Despite the various attempts to manipulate each of the above steps in some plant or the other, we are far from finding a univer-sal switch that controls NUE in all plants. However, transgenic studies and QTL approaches seem to increas-ingly suggest that the enzymes of secondary ammonia remobilization are better targets for manipulation, fol-lowed by regulatory processes that control N–C flux, rather than the individual genes/enzymes of primary ni-trate assimilation. However, it is possible that different plants respond differently to various targets of manipulat-ing NUE, especially since field-level improvements in NUE result from many more complex interactions. The
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need of the hour is integration of physiology and molecu-lar genetics involving Indian crop cultivars to optimize yields in different genotyopes and environmental condi-tions.
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交通事故三维模拟演示系统 产品简介 交通事故三维模拟演示系统集成了三维360度全景照相技术、三维虚拟现实动态仿真技术（增强现实技术）为一体，完全满足现在公安系统里现场全景照相、全景三维测量、三维重建、模拟、和分析的应用。是北京金视和科技有限公司集十几年来图形图像和三维仿真领域的尖端科研成果，并结合多年来对公安交通系统的调研数据进行定制化开发的解决方案。 交通事故三维模拟演示系统生成高度逼真的三维场景图片和动画片。把这些全景图片、三维场景、动画片和声音、文字结合，为侦查、技术、指挥人员生成各种三维虚拟案件现场场景的多媒体影音和影像材料。对这些数字化多媒体信息进行分析、演示，并可以在网络服务器上发布、保存、修改案例，其他用户可以通过网络服务器进行查询、观看案例。为案件的侦破、记录、汇报、存档查询，都提供了便利的直观方便。 交通事故三维模拟演示系统是由三维数字化图形软件和360°全自动机器 人拍摄系统组成。是基于图形图像和三维仿真领域的尖端科研成果，并结合多年来对交通事故处理部门的调研数据进行定制化开发的解决方案。 产品特点 交通事故三维模拟演示系统搭载的全景拍摄系统，由高端单反数码相机、精密鱼眼镜头和全自动拍摄云台组成，可以在一分钟内拍摄一组完整的现场全景图片，并以全自动方式进行拼接融合，无须人工干预拼接过程。达到交通事故现场快速全景重建的目的。 在传统的工作流程当中，由于人为、天气等外界因素干扰，事故现场很容易在短时间内遭到破坏和干扰。鉴于事故现场的特殊性，快速、完整、准确的保存事故现场，交通事故现场不可能像刑事案件现场那样长时间保留。交警在记录事故现场时，大多是通过昂贵的单反数码相机，直观的对事故现场进行大量的物证和场景拍摄，在后期分析事故现场时由于照片数量繁多，很难建立起事故现场的形象认知，甚至有可能会漏拍一些关键信息。借助360°全自动机器人拍摄系统将真实交通事故现场的完整的保存下来，可以在撤离交通事故现场后随时在交通事故现场全景图上进行截图、测量和分析。 现场采集物证图像及多场景热点添加在真实的交通事故现场中需要拍摄大量的现场细节图像(车辆痕迹、道路痕迹、现场环境、尸体、现场散落物和遗留物、血迹等)。但大量的现场图片容易让技术人员混淆物证，这对于日后的案情分析来说有重大影响。交通事故三维模拟演示系统的热点添加功能可以将所有采集到的现场细节图像以超级链接方式添加到现场全景图和三维重建现场中，并且可以用鼠标双击放大凸显细节图像，还可以创建文件夹对物证图像进行组织分类、可重命名以及删改细目照片资源，为事故过程分析带来极大的帮助。
Nature Communications 10.742，综合：一区，12.124 Nucleic Acid Research 8.808，生物：一区；10.162 Scientific Reports 5.078，综合类：二区，4.259 Methods 3.221，生物，二区，3.802 BMC Systems Biology 2.853，生物：3区，2.003 Journal of Biomedical informatics 2.482，医学：3区；2.753 Journal of Computational Biology 1.670，生物：四区；1.032 Journal of Bioinformatics and Computational Biology 0.931，生物：四区；0.800 Journal of Theoretical Biology1.833 生物、数学与计算生物学三区 Journal of Mathematical Biology 1.786 生物4区数学与计算生物学3区Bioinformatics (IF: 4.328) BMC Bioinformatics (IF: 3.781)，生物：三区；2.448 BMC Biology (IF: 4.734)，生物：一区；6.779 Briefings in Bioinformatics (IF: 4.627)，生物：一区；5.134 Journal of Computational Biology (IF: 1.563)，生物：四区；1.032 PLoS Computational Biology (IF: 5.895)，生物：二区，2.542 Mathematical Biosciences (IF: 1.148)，生物：四区；1.246 Journal of Biomedical Informatics (IF: 1.924)，医学：三区；2.753 Molecular Biosystems ( IF: 4.236)，生物：三区；2.781 Frontiers in Genetics 4.151 生物二区 Microbial Ecology 3.614 生物：二区，微生物3区
模拟演练与3D培训系统方案 煤科集团沈阳研究院有限公司 2014/2/28
一、模拟演练技术资料 DMX-135A仿真模拟与演练评价系统说明 1.系统型号 DMX-135 A 通道长度 多功能模拟训练系 统 2．系统简介 “3D-VR煤矿事故仿真和安全培训 演练系统”是我院与澳大利亚新南威尔 士大学合作开发的一套应用于煤矿安全培训的大型沉浸式仿真演练系统。我院通过借助UNSW(新南威尔士大学)的世界领先技术及软硬件平台，开发出符合我国国情的煤矿安全培训模块。本系统可由危险识别、灾害模拟、自救逃生、救护救援等多个安全培训模块组成，本系统模块是按照国家煤矿安全规程和新编煤矿安全技术培训教材编制
而成。采用虚拟现实（VR）技术、360度环屏投影播放技术、12.1环绕立体声技术、3D电影技术、计算机网络协同处理技术为煤矿工人安全和技能培训提供一流的“沉浸式”培训环境，将安全培训装备和质量提升到一个崭新的水平。 通过使用本系统，创建一个逼真的虚拟现实世界，使学员在体验各种真实场景同时，学习各模块相关操作知识，认识灾害的发生、发展过程及危害，并通过问答式的交互学习，快速掌握每个模块的操作步骤及要点。从而提高矿工的整体技术水平、思想素质、及各种突发状况的应对能力，从而使煤矿整体操作能力及防范意识得到提高，真正进入规范化管理阶段，降低各种事故发生的概率。 DMX-135A多功能模拟训练系统通道总长135米，分三层，旨在通
过仿真救灾现场的严峻条件，人为设置测试科目，使训练人员背负呼吸器，在黑暗、噪音、浓烟、高温的模拟条件下，按照预先设定的工作程序，完成正确穿越各种障碍，并按规定动作完成抢险、伤员营救等工作。它可以测量出训练人员最大身体承受能力和心理承受能力，评定受训人员能否正确使用呼吸器及抢险救援任务等的完成情况。 最 额定电压：380V，允许偏差±10%； 谐波：不大于5%； 频率：50Hz，允许偏差±5%； 3．3 系统组成 系统由以下部分组成:
摘要 随着我国汽车保有量的大幅度上升，高新技术产品和装置在汽车上的不断引入和普及与汽车维修业高素质从业人员不足之间的矛盾显得日益突出。发动机电控技术是汽车专业的一门核心技术，理论性与实践性很强。开发发动机电控系统模拟教学实验台，能便于学生认识和学习发动机电控系统的工作原理。发动机电控系统模拟实验台可以广泛应用于科研、教学等方面，通过对发动机工作过程的模拟、显示，可以提高汽车从业人员的知识掌握水平及实际操作能力，增强对汽车电控系统的认识和掌握，为学生学习和掌握发动机电控系统的工作原理提供帮助。 本设计是以教学展示为前提，主要介绍了发动机电控系统的控制内容、发展简史与前景、组成与工作原理，并在此基础上设计电控系统模拟实验台的相关内容。主要包括实验台架的设计、电控系统的零部件布置、电动机转速控制等内容。这个教学实验台能够演示发动机的起动和正常工作过程，并且设置了测量点。通过完成对实验台的设计，可以深刻理解和掌握发动机电控系统的组成和工作原理、机械设计与机械制图的相关知识，最终设计出一款及机械、电控于一体化的产品。 关键词：发动机电控系统；电动机控制；实验台；单片机；PWM
ABSTRACT With significant increase of the number of automobile，the contradiction between high-tech products and devices, the constant introduction in the car and popularization of high-quality vehicle maintenance trade and lack of practitioners become increasingly prominent. Engine electronic control technology is the theoretical and practical of a core technology and theoretical and practical very strong. Electronic control system simulation teaching test can make students to understand and learn the engine electronic control system works easy. Engine electronic control simulation system can be widely used in scientific research, teaching, etc. By displaying of the course of the engine simulation process, it can be employed to improve motor vehicle mastery level of knowledge and practical ability, and enhance the automotive electronic control system of understanding and mastering, for the students to learn and master the engine control system works to help. The design is based on the premise of teaching show, this paper introduces control content system of the engine electronic control, brief history of and prospects for development, composition and working principle and design on the basis of electronic control system simulation test-bed of related content. It mainly includes the design of bench testing, electrical control system layout of components, such as motor speed control. The teaching experiment platform to demonstrate the engine start and normal work processes, and set the measurement points. The design of the test-bed by accomplish can help learns to understand and master the engine electronic control system components, a final design and mechanical and electrical control products in the integration. Key words: Engine Electrical Control System；Motor Control；Test-bed；microcontroller；PWM
一、为了说明问题更有条理，我先对SCI/EI收录的会议论文进行说明： （1）EI收录主要收录在期刊上发表的国际会议和国际会议论文集。其中会议论文集、专著等。其中IEE/IEEE、SPIE、ASME、ASCE 等学会的国际会议论文集几乎全部收录。 （2）SCI、SSCI主要收录在期刊上发表的国际会议，如国际会议专刊、增刊，并收录在期刊上刊登的国际会议摘要。SCI、SSCI不收录国际会议论文集（图书）。 （3）ISTP、ISSHP主要收录在专著、期刊、报告、增刊及预印本等形式出版的各种一般会议、座谈、研究会和专题讨论会的会议录文献，包括CD-ROM，EI收录的会议ISTP不一定收录。 （4）部分会议会ISTP、ISSHP被同时收录。 二、对近来部分会议声称能被会议出版的说明： 近来有大量的会议声明能够被一些期刊，如AMR《Advanced Materials Research》，等期刊正刊出版，并且能够被EI检索，对此，大家要注意了，这里鱼目混杂，要擦亮眼睛注意： （1）AMR《Advanced Materials Research》，等这些刊物确实能够被EI检索，因为这几个刊物都是专门接受会议投稿的，也就是专门收录会议论文的，不接受作者的单独投稿。只要能被这个刊物收录可以说就一定能被EI检索，除非你的论文有重大的格式错误，但注意检索类型是CA类型（也就是会议论文）。
（2）论文能否进入这几个刊物，关键就是看你参加的会议是否能够属于刊物的会议列表里，最简单的方法是进入https://www.doczj.com/doc/fc10126058.html,/网站，输入你要查询的会议名称，如果该会议能够在此网站上查的到，才证明你的论文能够被该刊物收录，也就说明你的论文能够被Ei检索。 （3）这几个刊物都是属于瑞士TTP出版公司旗下的刊物，其旗下的刊物还有如下刊物，这些刊物上发表的文章都能被EI检索：MSF>Materials Science Forum KEM>Key Engineering Materials SSP>Solid State Phenomena DDF>Defect and Diffusion Forum AMM>Applied Mechanics and Materials AMR>Advanced Materials Research AST>Advances in Science and Technology JNanoR>Journal of Nano Research JBBTE>Journal of Biomimetics, Biomaterials, and Tissue Engineering JMNM>Journal of Metastable and Nanocrystalline Materials JERA>International Journal of Engineering Research in Africa （4）Key Engineering Materials 《关键工程材料》瑞士
第1章模拟演练系统 模拟训练系统软件应用上与其它终端台分离，形成一套能够独立完成模拟接处警过程和调度过程的软件，不影响系统正常的接处警工作。系统能够为操作人员、指挥员分别提供模拟演练功能以及在线考试功能，并能对训练和考试情况进行评估。模拟训练软件分为五大功能：典型案例查询、指挥员调度指挥训练、在线考试和训练质量评估。 典型案例查询 典型案例查询模块实现对典型案例进行查询，对查询结果进行浏览。根据查询信息可以演示的发生、发展及处臵的全过程。 指挥员训练试题维护 此功能用于添加、维护和删除指挥员训练的试题。其中又包括训练因素和训练试题维护。训练试题是由一个一个的训练因素组成，用户可以根据自己的需求来不断丰富训练因素库，从而达到生成情况复杂多样的指挥员训练试题的效果。 指挥员模拟训练 指挥员模拟训练模块则是训练、考核指挥员员的业务能力和调度水平。指挥员要为训练试题中的各种复杂因素制定出合理的调度方案，并给出详细的总体调度方案。 训练试题评审 接警员和指挥员的训练试题生成后还不能马上用来训练，必须经过有权限的领到审批发布后才会出现在可训练的试题库中。审批和发布是分开的，只有通过了审批的训练试题才可以发布。 训练评估 训练质量评估系统则是根据训练过程中系统记录下来的各项考核指标结果对训练质量人为的给出一个合理的评估。评估过程中系统将给出事先录入的标准答案。 虚拟现实(Virtual Reality)模拟训练 通过在训练中设定各种实战中的实际环境及情境，达到对实际情况的仿真，达到实战训练的效果。
在线考试 在线考试是基于WEB的一个功能模块，用户可以在线维护考试科目，考试题目，生成考卷，考试，查询成绩等。
智能用电综合模拟演示平台的建设 邵瑾，李铮，张晶 （中国电力科学研究院，北京市海淀区 100192） CONSTRUCTION OF COMPREHENSIVE SIMULATION AND DEMO PLATFORM FOR SMART ELECTRIC CONSUMPTION SHAO Jin, LI Zheng, ZHANG Jing (China Electric Power Research Institute, Haidian District, Beijing 100192, China) ABSTRACT: This paper analyzes need and practical significance of comprehensive simulation and demo platform of smart electric consumption, present with construction principle, system structure, function module, networking of communication, and application. The focus of discussion is put on design scheme for functional modules, such as load management, monitoring of distribution transformer, automatic meter reading and monitoring of unusual electricity consumption. Finally, summary and expectation is forwarded to application of the demo platform. KEY WORDS: smart grid, smart electric consumption, comprehensive simulation, demo platform 摘要：本文分析了智能用电综合模拟演示平台的需求和现实意义，介绍了演示平台的建设原则、系统结构、功能模块、通信组网、应用分析等内容。重点介绍了负荷管理、配变监测、集中抄表及异常用电监测等功能模块的设计方案，最后对演示平台的应用进行了总结和展望。 关键词：智能电网，智能用电，综合模拟，演示平台 1引言 利用现代通信技术、信息技术、营销技术，建设智能用电服务体系是智能电网的重要内容之一。智能用电，依托坚强电网和现代管理理念，利用高级量测、高效控制、高速通信、快速储能等技术，实现市场响应迅速、计量公正准确、数据实时采集、收费方式多样、服务高效便捷，构建智能电网与电力用户电力流、信息流、业务流实时互动的新型供用电关系。将供电端到用户端的所有设备，透过传感器连接，形成紧密完整的用电网络，并对信息加以整合分析，实现电力资源的最佳配置，达到降低用户用电成本、提升可靠性、提高用电效率的目的。 智能用电综合模拟演示平台（以下称演示平台），是智能用电各种专业系统和技术的集成实验环境。演示平台既是一个一体化的数据采集和监控系统，也是一个硬件、软件、业务、技术高度融合的模拟实验平台。演示平台是以软件为中枢指挥、设备为支撑骨架、信道为信息通道、功能为业务流程、展示为技术目标的综合模拟系统，该平台的应用对于引领智能电网科技创新，展示和验证智能用电和智能通信科技成果、宣传普及节能减排和清洁能源利用都具有重要意义。 2演示平台建设原则 演示平台建设原则是分阶段原则、分模块原则与可扩展原则。 分阶段原则：建设初期是已现有用电信息采集系统为基础，包括负荷管理、配变监测、集中抄表和异常用电监测等内容。建设后期演示平台将不断引入智能用电最新技术的研究和应用成果，对初期平台进行改进和完善。 分模块原则：智能用电涉及的内容很多，这就需要选择主要和典型的功能和业务，通过建立功能模块的方式对各项功能和业务进行综合展示。 可扩展原则：考虑到未来智能电网新标准、新规范和新技术的应用，对系统的软硬件设备都会造成一定的影响，因此在整个系统和设备的冗余度、开放性和接口设计上预留有足够的扩展空间，为未来的系统及设备升级和扩展做好技术准备。 3演示平台系统结构
系统演示方案 编写本方案目的在于，演示时有较好的步骤性和目的性，充分演示系统的各种功能及性能。 1、系统初始状态 系统的初始状态如下，各PLC均为停机状态，通信控制服务器设备状态表显示均为黄点显示。 2、系统的启动 1、首先启动各上位机服务器，然后通过查询分析器模拟工程师服务器启动MPLC，命令如下： SP_NewCommand 'Engineer_Server','Comunication_Server','SB08','Z000','KJ' 执行此命令后，通信控制服务器中设备状态表炉门PLC应为运行状态，绿点显示。指令表中正确显示各指令。 2、然后依次开启HPLC1～HPLC4 SP_NewCommand 'Engineer_Server','Comunication_Server','SB02','Z000','KJ' SP_NewCommand 'Engineer_Server','Comunication_Server','SB03','Z000','KJ' SP_NewCommand 'Engineer_Server','Comunication_Server','SB04','Z000','KJ' SP_NewCommand 'Engineer_Server','Comunication_Server','SB05','Z000','KJ' 通信控制服务器中各PLC应显示正确状态。 3、通过PLC模拟程序，模拟CPLC1和ZPLC1上传请求开机指令。 @XT03Z100SB06QQKJ 1196# @XT04Z100SB07QQKJ 1198# 通信控制服务器应做出正确应答，并开启相应PLC，设备列表显示
如何查询期刊影响因子 影响因子是一个国际上通行的期刊评价指标，表示期刊影响力大小。近年来，科研工作者越来越重视期刊的影响因子。那么，怎么查询期刊的影响因子呢？ 首先，查询影响因子要知道具体的查询地址，外文期刊和中文期刊的查询地址不同。 1、查询外文期刊影响因子，可使用外文数据库Web of Science中的JCR，其中JCR Science Edition 用于查询自然科学类期刊，JCR Social Sciences Edition 用于查询人文社会科学类期刊。 2、查询中文期刊的影响因子，可使用中国学术期刊（光盘版）电子杂志社和中国科学文献计量评价中心联合推出的《中国学术期刊综合引证报告》（万锦堃主编，科学出版社）。有需要的读者请到图书馆咨询部查询。 其次，查询影响因子必需知道期刊缩写名，这个有很多规则，具体如下： 1.单个词组成的刊名不得缩写 部分刊名由一个实词组成，如Biomaterials，nature，science等不得缩写。 2.刊名中单音节词一般不缩写 英文期刊中有许多单音节词，如FOOD，CHEST，CHILD，这些词不得缩写。如医学期刊hearand lung, 缩写为Heart Lung,仅略去连词and.但少数构成地名的单词，如NEW，SOUTH等，可缩写成相应首字字母。如New England Journal of Medcine,可缩写为N Engl J Med,不应略为New Engl J Med，South African Journal of Surgery可缩写为S Afr J Surg,不可缩写为South Afr J Surg.另外，少于5个字母(含5个字母)的单词一般不缩写，如Acta,Heart,Bone,Joint等均不缩写。 3.刊名中的虚词一律省略
序号期刊名称主办单位影响因子 1 浙江社会科学浙江社会科学界联合会0.485 2 求是学刊黑龙江大学0.312 3 社会科学上海社会科学院0.455 4 社会科学辑刊辽宁省社会科学院0.244 5 武汉大学学报(人文科学版) 武汉大学0.194 6 湖南师范大学社会科学学报湖南师范大学0.327 7 福建论坛(人文社会科学版) 福建社会科学院0.240 8 探索中共重庆市委党校0.345 9 敦煌研究敦煌研究院0.167 10 统计研究中国统计学会;国家统计局统计科学研究所0.939 11 中国社会保障劳动和社会保障部社会保险局0.140 12 管理世界中华人民共和国国务院发展研究中心2.899 13 俄罗斯中亚东欧研究罗斯东欧中亚研究所0.388 14 毛泽东思想研究四川省社会科学院;四川省社会科学界联合会;中共四川省委党史研究室0.123 15 现代法学西南政法大学0.958 16 人民检察最高人民检察院0.475 17 人民司法最高人民法院0.389 18 当代财经江西财经大学0.674 19 当代经济科学西安交通大学0.710 20 生态经济云南教育出版社0.416 21 涉外税务中国国际税收研究会;深圳市国际税收研究会0.607 22 新闻战线人民日报社0.201 23 电视研究中国中央电视台0.189 24 中国出版中国出版杂志社0.246 25 出版发行研究中国出版科学研究所0.167 26 课程.教材.教法人民教育出版社;课程教材研究所1.217 27 外语教学与研究北京外国语大学3.510 28 文学评论中国社会科学院文学研究所0.858 29 清明安微省文联0.000 30 时代文学山东省作家协会0.000 31 作家吉林省作家协会0.043 32 花城花城出版社0.000 33 史学月刊河南大学;河南省历史学会0.282 34 华中科技大学学报(自然科学版) 华中科技大学0.362 35 上海交通大学学报上海交通大学0.411 36 中山大学学报(自然科学版) 中山大学0.596 37 哈尔滨工业大学学报哈尔滨工业大学0.437 38 北京师范大学学报(自然科学版) 北京师范大学0.303 39 天津大学学报天津大学0.319 40 东北大学学报(自然科学版) 东北大学0.637 41 同济大学学报(自然科学版) 同济大学0.422 42 北京理工大学学报北京理工大学0.422