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NIEHS REPORT onHealth Effects from Exposure to Power-Line Frequency Electric and Magnetic FieldsPrepared in Response to the 1992 Energy Policy Act(PL 102-486, Section 2118)National Institute of Environmental Health SciencesNational Institutes of HealthDr. Kenneth Olden, DirectorPrepared by theNIEHS EMF-RAPID Program StaffNIH Publication No. 99-4493Supported by the NIEHS/DOEDEPARTMENT OF HEALTH & HUMAN SERVICES Public Health ServiceNational Institutes of HealthNational Institute ofEnvironmental Health SciencesP. O. Box 12233Research Triangle Park, NC 27709 May 4, 1999Dear Reader:In 1992, the U.S. Congress authorized the Electric and Magnetic Fields Research and Public Information Dissemination Program (EMF-RAPID Program) in the Energy Policy Act. The Congress instructed the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health and the U.S. Department of Energy (DOE) to direct and manage a program of research and analysis aimed at providing scientific evidence to clarify the potential for health risks from exposure to extremely low frequency electric and magnetic fields (ELF-EMF). The EMF-RAPID Program had three basic components: 1) a research program focusing on health effects research, 2) information compilation and public outreach and 3) a health assessment for evaluation of any potential hazards arising from exposure to ELF-EMF. The NIEHS was directed to oversee the health effects research and evaluation, and the DOE was given the responsibility for overall administration of funding and engineering research aimed at characterizing and mitigating these fields. The Director of the NIEHS was mandated upon completion of the Program to provide this report outlining the possible human health risks associated with exposure to ELF-EMF. The scientific evidence used in preparation of this report has undergone extensive scientific and public review. The entire process was open and transparent. Anyone who wanted “to have a say” was provided the opportunity.The scientific evidence suggesting that ELF-EMF exposures pose any health risk is weak. The strongest evidence for health effects comes from associations observed in human populations with two forms of cancer: childhood leukemia and chronic lymphocytic leukemia in occupationally exposed adults. While the support from individual studies is weak, the epidemiological studies demonstrate, for some methods of measuring exposure, a fairly consistent pattern of a small, increased risk with increasing exposure that is somewhat weaker for chronic lymphocytic leukemia than for childhood leukemia. In contrast, the mechanistic studies and the animal toxicology literature fail to demonstrate any consistent pattern across studies although sporadic findings of biological effects have been reported. No indication of increased leukemias in experimental animals has been observed.The lack of connection between the human data and the experimental data (animal and mechanistic) severely complicates the interpretation of these results. The human data are in the "right" species, are tied to "real life" exposures and show some consistency that is difficult to ignore. This assessment is tempered by the observation that given the weak magnitude of these increased risks, some other factor or common source of error could explain these findings. However, no consistent explanation other than exposure to ELF-EMF has been identified.Page 2Epidemiological studies have serious limitations in their ability to demonstrate a cause and effect relationship whereas laboratory studies, by design, can clearly show that cause and effect are possible. Virtually all of the laboratory evidence in animals and humans and most of the mechanistic work done in cells fail to support a causal relationship between exposure to ELF-EMF at environmental levels and changes in biological function or disease status. The lack of consistent, positive findings in animal or mechanistic studies weakens the belief that this association is actually due to ELF-EMF, but it cannot completely discount the epidemiological findings.The NIEHS concludes that ELF-EMF exposure cannot be recognized at this time as entirely safe because of weak scientific evidence that exposure may pose a leukemia hazard. In my opinion, the conclusion of this report is insufficient to warrant aggressive regulatory concern. However, because virtually everyone in the United States uses electricity and therefore is routinely exposed to ELF-EMF, passive regulatory action is warranted such as a continued emphasis on educating both the public and the regulated community on means aimed at reducing exposures. The NIEHS does not believe that other cancers or non-cancer health outcomes provide sufficient evidence of a risk to currently warrant concern. The interaction of humans with ELF-EMF is complicated and will undoubtedly continue to be an area of public concern. The EMF-RAPID Program successfully contributed to the scientific knowledge on ELF-EMF through its support of high quality, hypothesis-based research. While some questions were answered, others remain. Building upon the knowledge base developed under the EMF-RAPID Program, meritorious research on ELF-EMF through carefully designed, hypothesis-driven studies should continue for areas warranting fundamental study including leukemia. Recent research in two areas, neurodegenerative diseases and cardiac diseases associated with heart rate variability, have identified some interesting and novel findings for which further study is ongoing. Advocacy groups have opposing views concerning the health effects of ELF-EMF. Some advocacy groups want complete exoneration and others want a more serious indictment. Our conclusions are prudent and consistent with the scientific data. I am satisfied with the report and believe it provides a pragmatic, scientifically-driven basis for any further regulatory review.I am pleased to transmit this report to the U.S. Congress.Sincerely,Kenneth Olden, Ph.D.DirectorNIEHS EMF-RAPID P ROGRAM S TAFF Gary A. Boorman, D.V.M., Ph.D., Associate Director for Special Programs, Environmental Toxicology Program and Director, EMF-RAPID ProgramNaomi J. Bernheim, M.S., Biologist, Office of Special Programs, Environmental Toxicology Program and Program Assistant, EMF-RAPID ProgramMichael J. Galvin, Ph.D., Health Scientist Administrator, Division of Extramural Research and Training and Extramural Program Administrator, EMF-RAPIDProgramSheila A. Newton, Ph.D., Director, Office of Policy, Planning and EvaluationFred M. Parham, Ph.D., Staff Scientist, Laboratory of Computational Biology and Risk AnalysisChristopher J. Portier, Ph.D., Associate Director for Risk Assessment, Environmental Toxicology Program; Chief, Laboratory of Computational Biology and RiskAnalysis; and Coordinator, EMF Hazard EvaluationMary S. Wolfe, Ph.D., Associate Coordinator, EMF Hazard Evaluation, Environmental Toxicology ProgramA CKNOWLEDGEMENTSThis report would not have been possible without the concerted and generous help of literally hundreds of research scientists. Many of the scientists who wrote the articles, which are cited in this report, attended our science review symposia where their research was carefully evaluated and critiqued. Their patience with our questions and their professional attitude in evaluating their own work was extraordinary and is greatly appreciated. We are also indebted to the many scientists from outside of the electric and magnetic fields (EMF) research community who participated in our symposia and spent time and effort evaluating these data on our behalf; this provides a clear example of the dedication of scientists concerned about health issues.Special thanks are extended to the 30 scientists who attended the Working Group Meeting in June 1998. Their hard work and conscientious effort led to one of the most concise and clear reviews of the extremely low frequency (ELF) EMF literature ever developed. The thousands of man-hours extended by this group in such a short period of time provided us with a background document on ELF-EMF health risks that made this report a much simpler task. We wish especially to thank Dr. Arnold Brown for attending our public meetings on the Working Group Report; his extensive experience and insightful comments helped to make these meetings a great success. We would also like to thank Dr. Brown and Dr. Paul Gailey for reviewing this report prior to its release and Mr. Fred Dietrich for advising us on exposure issues during the preparation of this document. Finally we would like to acknowledge the U.S. Department of Energy as our partner in the EMF-RAPID Program and its EMF program officer, Dr. Imre Gyuk.T ABLE OF C ONTENTSEXECUTIVE SUMMARY (i)I NTRODUCTION (i)NIEHS C ONCLUSION (ii)B ACKGROUND (iii)Program Oversight and Management (iii)ELF-EMF Health Effects Research (iv)Information Dissemination and Public Outreach (iv)Health Risk Assessment of ELF-EMF Exposure (v)INTRODUCTION (1)Funding (2)Oversight and Program Management (3)ELF-EMF Health Effects Research (3)Information Dissemination and Public Outreach (4)Literature Review and Health Risk Assessment (6)DO ELECTRIC AND MAGNETIC FIELDS POSE A HEALTH RISK? (9)S CIENTIFIC E VIDENCE S UPPORTING T HIS C ONCLUSION (10)Background on the Limitations of Epidemiology Studies (10)Childhood Cancers (12)Adult Cancers (15)Non-Cancer Findings in Humans (16)Animal Cancer Data (19)Non-Cancer Health Effects in Experimental Animals (23)Studies of Cellular Effects of ELF-EMF (25)Biophysical Theory (29)HOW HIGH ARE EXPOSURES IN THE U.S. POPULATION? (31)CONCLUSIONS AND RECOMMENDATIONS (35)Previous Panel Reviews (35)NIEHS Conclusion (35)Recommended Actions (37)Future Research (38)REFERENCES (41)E XECUTIVE S UMMARYIntroductionElectrical energy has been used to great advantage for over 100 years. Associated with the generation, transmission, and use of electrical energy is the production of weak electric and magnetic fields (EMF). In the United States, electricity isusually delivered as alternating current that oscillates at 60 cycles per second(Hertz, Hz) putting fields generated by this electrical energy in the extremely low frequency (ELF) range.Prior to 1979 there was limited awareness of any potential adverse effects fromthe use of electricity aside from possible electrocution associated with directcontact or fire from faulty wiring. Interest in this area was catalyzed with thereport of a possible association between childhood cancer mortality and proximity of homes to power distribution lines. Over the next dozen years, the U.S.Department of Energy (DOE) and others conducted numerous studies on theeffects of ELF-EMF on biological systems that helped to clarify the risks andprovide increased understanding. Despite much study in this area, considerabledebate remained over what, if any, health effects could be attributed to ELF-EMF exposure.In 1992, the U.S. Congress authorized the Electric and Magnetic Fields Research and Public Information Dissemination Program (EMF-RAPID Program) in theEnergy Policy Act (PL 102-486, Section 2118). The Congress instructed theNational Institute of Environmental Health Sciences (NIEHS), National Institutes of Health and the DOE to direct and manage a program of research and analysisaimed at providing scientific evidence to clarify the potential for health risks from exposure to ELF-EMF. The EMF-RAPID Program had three basic components:1) a research program focusing on health effects research, 2) informationcompilation and public outreach and 3) a health assessment for evaluation of any potential hazards arising from exposure to ELF-EMF. The NIEHS was directedto oversee the health effects research and evaluation and the DOE was given theresponsibility for overall administration of funding and engineering researchaimed at characterizing and mitigating these fields. The Director of the NIEHSwas mandated upon completion of the Program to provide a report outlining thepossible human health risks associated with exposure to ELF-EMF. Thisdocument responds to this requirement of the law.This five-year effort was signed into law in October 1992 and provisions of thisAct were extended for one year in 1997. The Program ended December 31, 1998.The EMF-RAPID Program was funded jointly by Federal and matching privatefunds and has been an extremely successful Federal/private partnership withsubstantial financial support from the utility industry. The NIEHS received$30.1 million from this program for research, public outreach, administration and the health assessment evaluation of ELF-EMF. In addition to EMF-RAPIDProgram funds from the DOE, the NIEHS contributed $14.5 million for support of extramural and intramural research including long-term toxicity studies conducted by the National Toxicology Program.NIEHS ConclusionThe scientific evidence suggesting that ELF-EMF exposures pose any health risk is weak. The strongest evidence for health effects comes from associationsobserved in human populations with two forms of cancer: childhood leukemia and chronic lymphocytic leukemia in occupationally exposed adults. While thesupport from individual studies is weak, the epidemiological studies demonstrate, for some methods of measuring exposure, a fairly consistent pattern of a small,increased risk with increasing exposure that is somewhat weaker for chroniclymphocytic leukemia than for childhood leukemia. In contrast, the mechanisticstudies and the animal toxicology literature fail to demonstrate any consistentpattern across studies although sporadic findings of biological effects (includingincreased cancers in animals) have been reported. No indication of increasedleukemias in experimental animals has been observed.The lack of connection between the human data and the experimental data (animal and mechanistic) severely complicates the interpretation of these results. Thehuman data are in the “right” species, are tied to “real-life” exposures and showsome consistency that is difficult to ignore. This assessment is tempered by theobservation that given the weak magnitude of these increased risks, some otherfactor or common source of error could explain these findings. However, noconsistent explanation other than exposure to ELF-EMF has been identified.Epidemiological studies have serious limitations in their ability to demonstrate acause and effect relationship whereas laboratory studies, by design, can clearlyshow that cause and effect are possible. Virtually all of the laboratory evidence in animals and humans and most of the mechanistic work done in cells fail tosupport a causal relationship between exposure to ELF-EMF at environmentallevels and changes in biological function or disease status. The lack of consistent, positive findings in animal or mechanistic studies weakens the belief that thisassociation is actually due to ELF-EMF, but it cannot completely discount theepidemiological findings.The NIEHS concludes that ELF-EMF exposure cannot be recognized as entirelysafe because of weak scientific evidence that exposure may pose a leukemiahazard. In our opinion, this finding is insufficient to warrant aggressiveregulatory concern. However, because virtually everyone in the United Statesuses electricity and therefore is routinely exposed to ELF-EMF, passiveregulatory action is warranted such as a continued emphasis on educating both the public and the regulated community on means aimed at reducing exposures. The NIEHS does not believe that other cancers or non-cancer health outcomes provide sufficient evidence of a risk to currently warrant concern.The interaction of humans with ELF-EMF is complicated and will undoubtedlycontinue to be an area of public concern. The EMF-RAPID Program successfully contributed to the scientific knowledge on ELF-EMF through its support of highquality, hypothesis-based research. While some questions were answered, others remain. Building upon the knowledge base developed under the EMF-RAPIDProgram, meritorious research on ELF-EMF through carefully designed,hypothesis-driven studies should continue for areas warranting fundamental study including leukemia. Recent research in two areas, neurodegenerative diseases and cardiac diseases associated with heart rate variability, have identified someinteresting and novel findings for which further study is ongoing.BackgroundProgram Oversight and ManagementThe 1992 Energy Policy Act created two committees to provide guidance anddirection to this program. The first, the Interagency Committee (IAC), wasestablished by the President of the United States and composed of representatives from the NIEHS, the DOE and seven other Federal agencies with responsibilities related to ELF-EMF. This group receives the report from the NIEHS Directorand must prepare its own report for Congress. The IAC had responsibility fordeveloping a strategic research agenda for the EMF-RAPID Program, facilitating interagency coordination of Federal research activities and communication to the public and monitoring and evaluating the Program.The second committee, the National EMF Advisory Committee (NEMFAC),consisted of representatives from public interest groups, organized labor, stategovernments and industry. This group was involved in all aspects of theEMF-RAPID Program providing advice and critical review to the DOE and theNIEHS on the design and implementation of the EMF-RAPID Program’sactivities.ELF-EMF Health Effects ResearchThe EMF-RAPID Program’s health effects research initiative relied upon accepted principles of hazard identification and risk assessment to establish priorities. All studies supported by the NIEHS and the DOE under this program were selected for their potential to provide solid, scientific data on whetherELF-EMF exposure represents a human health hazard, and if so, whether risks are increased under exposure conditions in the general population. Research efforts did not focus on epidemiological studies (i.e. those in the human population) because of time constraints and the number of ongoing, well-conducted studies. The NIEHS health effects research program focused on mechanistic, cellular and laboratory studies in the areas of neurophysiology, behavior, reproduction, development, cellular research, genetic research, cancer and melatonin. Mechanistic, cellular and laboratory studies are part of the overall criteria used to determine causality in interpreting epidemiological studies. In this situation, the most cost-effective and efficient use of the EMF-RAPID Program’s research funds was clearly for trying to clarify existing associations identified from population studies. The DOE research initiatives focused on assessment of exposure and techniques of mitigation.The EMF-RAPID Program through the combined efforts of the NIEHS and the DOE radically changed and markedly improved the quality of ELF-EMF research. This was accomplished by providing biological and engineering expertise to investigators and emphasizing hypothesis-driven, peer-reviewed research. Four regional facilities were also set-up where state-of-the-art magnetic field exposure systems were available for in-house and outside investigators to conduct mechanistic research. The EMF-RAPID Program through rigorous review and use of multi-disciplinary research teams greatly enhanced the understanding of the interaction of biological systems with ELF-EMF. Information Dissemination and Public OutreachThe EMF-RAPID Program provided the public, regulated industry and scientists with useful, targeted information that addressed the issue of uncertainty regarding ELF-EMF health effects. Two booklets, a question and answer booklet onELF-EMF and a layman’s booklet addressing ELF-EMF in the workplace, were published. A telephone information line for ELF-EMF was available where callers could request copies of ELF-EMF documents and receive answers to standard questions from operators. The NIEHS also developed a web-site for the EMF-RAPID Program where all of the Program’s documents are on-line and links are available to other useful sites on ELF-EMF. Efforts were made to include the public in EMF-RAPID Program activities through sponsorship of scholarships to meetings; holding open, scientific workshops; and setting aside a two-month period for public comment and review on ELF-EMF and the workshop reports. In addition, the NIEHS sponsored attendance of NEMFACmembers at relevant scientific meetings and at each of the public comment meetings.Health Risk Assessment of ELF-EMF ExposureIn preparation of the NIEHS Director’s Report, the NIEHS developed a process to evaluate the potential health hazards of ELF-EMF exposure that was designed to be open, transparent, objective, scholarly and timely under the mandate of the 1992 Energy Policy Act. The NIEHS used a three-tiered strategy for collection and evaluation of the scientific information on ELF-EMF that included: 1) three science review symposia for targeted ELF-EMF research areas, 2) a working group meeting and 3) a period of public review and comment. Each of the three symposia focused on a different, broad area of ELF-EMF research: mechanistic and cellular research (24-27 March 1997, Durham, NC), human population studies (12-14 January 1998, San Antonio, TX) and laboratory human and clinical work (6-9 April 1998, Phoenix, AZ). These meetings were aimed at including a broad spectrum of the research community and the public in the evaluation of ELF-EMF health hazards, identifying key research findings and providing opinion on the quality of this research. Discussion reports from small discussion groups held for specific topics were prepared for each meeting.Following the symposia, a working group meeting (16-24 June 1998, Brooklyn Park, MN) was held where a scientific panel reviewed historical and novel evidence on ELF-EMF and determined the strength of the evidence for human health and biological effects. Stakeholders and the public attended this meeting and were given the opportunity to comment during the process. The Working Group conducted a formal, comprehensive review of the literature for research areas identified from the symposia as being important to the assessment ofELF-EMF-related biological or health effects. Separate draft documents covering areas of animal carcinogenicity, animal non-cancer findings, physiological effects, cellular effects, theories and human population studies (epidemiology studies) in children and adults for both occupational and residential ELF-EMF exposures were rewritten into a single book. The Working Group characterized the strength of the evidence for a causative link between ELF-EMF exposure and disease in each category of research using the criteria developed by the International Agency for Research on Cancer (IARC).The IARC criteria fall into four basic categories: sufficient, limited, inadequate and evidence suggesting the lack of an effect. After critical review and discussion, members of the Working Group were asked to determine the categorization for each research area; the range of responses reflected the scientific uncertainty in each area. A majority of the Working Group members concluded that childhood leukemia and adult chronic lymphocytic leukemia from occupational exposure were areas of concern. For other cancers and for non-cancer health endpoints, the Working Group categorized the experimental data asproviding much weaker evidence or no support for effects from exposure to ELF-EMF.Following the Working Group Meeting, the NIEHS established a formal review period for solicitation of comments on the symposia and Working Group reports. The NIEHS hosted four public meetings (14-15 September 1998, Tucson, AZ;28 September, Washington, DC; 1 October 1998, San Francisco, CA; and5 October 1998, Chicago, IL) where individuals and groups could voice their opinions; the meetings were recorded and transcripts prepared. In addition, the NIEHS received 178 written comments that were also reviewed in preparation of this report. The remarks that NIEHS received covered many areas related to ELF-EMF and provided insight about areas of concern on behalf of the public, researchers, regulatory agencies and industry.I NTRODUCTIONElectricity is used to the benefit of people all over the world. Wherever electricity is generated, transmitted or used, electric fields and magnetic fields are created. These fields are a direct consequence of the presence and/or motion of electric charges. It is impossible to generate and use electrical energy without creating these fields; hence they are an inevitable consequence of our reliance on this form of energy. Electrical energy is generally supplied as alternating current where the electricity flows in one direction and then in the other to complete a cycle. The number of cycles completed in a fixed period of time (such as a second) is known as the frequency and is generally measured in units of Hertz (Hz), which are cycles per second. In the United States, electricity is usually delivered as 60 Hz alternating current; 50 to 60 Hz cycles are generally referred to as the power-line frequency of alternating current electricity. Just as alternating current electricity has a frequency, so do the associated electric and magnetic fields (EMF). Thus, 60 Hz alternating current electricity will generate a 60 Hz electric field and a60 Hz magnetic field. EMF with cycle frequencies of greater than 3 Hz and less that 3000 Hz is generally referred to as extremely low frequency (ELF) EMF. In addition to magnetic fields associated with electricity, the earth also has a static magnetic field (frequency of 0 Hz) that varies by location from approximately 30 to 50 µT.Electricity has been used, to great advantage, for 100 years and with this widespread use, there has been limited awareness of any potential adverse health effects other than effects caused by direct contact such as electrocution or by faulty wiring such as fire. Research into potential health effects caused by the ELF-EMF resulting from indirect exposure to electrical energy has been underway for several decades. The catalyst that sparked increased study in this area of research was the 1979 report by Wertheimer and Leeper (1) that children living near power lines had an increased risk for developing cancer. Since that initial finding, there have been numerous studies of human populations, animals and isolated cells aimed at clarification of the observations of Wertheimer and Leeper and others. Despite this multitude of research, considerable debate remains over what, if any, health effects can be attributed to ELF-EMF exposure. In 1992, under the Energy Policy Act (PL 102-486, Section 2118), the U.S. Congress instructed the National Institute of Environmental Health Sciences(NIEHS), National Institutes of Health and the U.S. Department of Energy (DOE) to direct and manage a program of research and analysis aimed at providing scientific evidence to clarify the potential for health risks from exposure toELF-EMF. This resulted in formation of the EMF Research and Public Information Dissemination Program (EMF-RAPID Program). The EMF-RAPID Program had three basic components: 1) a research program focusing on health effects research primarily through mechanistic studies of ELF-EMF and engineering research targeting measurement, characterization and management of ELF-EMF; 2) information compilation and dissemination through brochures, public outreach and an ELF-EMF information line for communicating with the public; and 3) a health assessment including an analysis of the research data aimed at summarizing the strength of the evidence for evaluation of any hazard possibly arising from exposure to ELF-EMF. The NIEHS was directed to oversee the health effects research and evaluation and the DOE was given responsibility for engineering research aimed at characterizing and mitigating these fields. Under the Energy Policy Act, the Director of the NIEHS is mandated upon completion of the EMF-RAPID Program to provide a report outlining the possible human health risks associated with exposure to ELF-EMF. This document responds to this requirement of the law.FundingThe EMF-RAPID Program was funded jointly by Federal and matching private funds; through fiscal year 1998, authorized funding for this program was approximately $46 million. Administration of funding for the EMF-RAPID Program was the responsibility of the DOE with funds for NIEHS-sponsored program activities transferred from the DOE to the NIEHS. The EMF-RAPID Program has been an extremely successful Federal/private partnership with substantial financial support from the utility industry. The NIEHS received $30.1 million from this program for research, public outreach, administration and the health assessment evaluation of ELF-EMF. Of the funds received, the NIEHS spent the majority (89%) for research through grants and contracts. The remainder was used for public outreach/administration (2%) and the health risk evaluation (9%). In addition to EMF-RAPID Program funds from the DOE, the NIEHS contributed $14.5 million for support of extramural grants and contracts and intramural research as well as long-term toxicity studies conducted by the National Toxicology Program.。
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摘要随着我国社会主义市场经济的迅速发展，资本市场的不断完善，价值评估在公司进行财务管理、对外投资、兼并收购中的应用日益频繁。
目前，价值评估理论在经过了长期的研究后，已经形成了完整的理论体系，并在实际工作中得到广泛应用。
在此基础上，文章研究公司价值评估的相关理论、实践问题，尤其是利用自由现金流量折现法评估公司价值。
在肯定了自由现金流量折现法的实际可操作性以及模型改良后，对该方法在理论和应用中存在的其他问题提出对策建议。
关键词：自由现金流；蒙牛乳业；价值评估AbstractWith the rapid development of our country socialist market economy, the continuous improvement of the capital market, value evaluation in company financial management, the application of foreign investment, merger and acquisition is becoming more and more frequent. At present, the value assessment theory after the long-term research, has formed a complete theoretical system, and is widely applied in the practical work. On this basis, the article studies the value of the company evaluate the relevant theories and practical problems, especially the free cash flow discount method is used to evaluate the value of the company. In the affirmation of the free cash flow discount method after actual operability, and modified model, in theory and application of this method in other problems of the countermeasures and Suggestions are put forward.Keywords:Freecashflow;Mengniu;Valueevaluation目录1 绪论1.1研究背景 (1)1.2研究的意义 (1)1.3国内外研究现状 (2)1.3.1国内研究现状 (2)1.3.1国外研究现状 (1)2公司价值评估的相关理论2.1公司价值评估的概念 (4)2.2价值评估的方法 (4)2.3基于自由现金流的企业价值评估 (4)2.3.1自由现金流量折现法的基本原则 (4)2.3.2自由现金流量模型的因素分析 (5)2.3.3自由现金流与企业价值的相关性 (5)3蒙牛企业的价值评估案例分析3.1行业分析 (6)3.1.1消费量及普及率大幅上升 (6)3.1.2竞争日益激烈 (6)3.1.3行业现状 (6)3.2蒙牛乳业背景 (7)3.3蒙牛乳业的评估过程 (7)3.3.1对自由现金流量的预测 (7)3.3.2折现率的估计 (9)3.3.3蒙牛乳业的价值估算 (10)4结论与建议4.1对蒙牛乳业的自由现金流价值评估的总结 (12)4.2对自由现金流的价值评估的建议 (12)4.2.1健全国内市场环境 (12)4.2.2法律制度的完善 (13)4.2.3积极完善信息披露制度 (13)参考文献 (14)致谢 (15)1 绪论1.1 研究背景二十世纪五十年代初期，伴随着产权市场的出现，专门从事企业买卖的产权市场迅速发展，使人们日益清楚地认识到，在市场经济条件下，作为商品生产者的企业本身也是一种商品。
2013 AHA/ACC/TOS成人超重和肥胖管理指南：美国心脏病学会/美国心脏协会实践指南专责组/肥胖协会报告2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults:A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines andThe Obesity SocietyMichael D. Jensen, Donna H. Ryan, Caroline M. Apovian, Jamy D. Ard, Anthony G. Comuzzie, Karen A. Donato, Frank B.Hu, Van S. Hubbard, John M. Jakicic, Robert F. Kushner, Catherine M. Loria, Barbara E. Millen, Cathy A. Nonas, F.Xavier Pi-Sunyer, June Stevens, Victor J. Stevens, Thomas A. Wadden, Bruce M. Wolfe and Susan Z. YanovskiCirculation. published online November 12, 2013;Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231Copyright © 2013 American Heart Association, Inc. All rights reserved.Print ISSN:0009-7322. Online ISSN: 1524-4539本文网上版及更新信息和服务，位于互联网：/content/early/2013/11/11/01.cir.0000437739.71477.ee.citationData Supplement (unedited) a/content/suppl/2013/11/07/01.cir.0000437739.71477.ee.DC1.html2013 AHA/ACC/TOS成人超重和肥胖管理指南美国心脏病学会/美国心脏协会实践指南专责组/肥胖协会报告美国心肺康复协会（American Association of Cardiovascular and Pulmonary Rehabilitation），美国药师协会（American Pharmacists Association），美国营养协会（American Society for Nutrition），美国预防心脏病协会（American Society for Preventive Cardiology），美国高血压协会（American Society of Hypertension），黑人心脏病医生协会（Association of Black Cardiologists），全国血脂协会（National Lipid Association），预防心血管护理协会（Preventive Cardiovascular Nurses Association），内分泌协会（The Endocrine Society）和妇女心脏（WomenHeart）：全国妇女心脏病联合会（The National Coalition for Women with Heart Disease）认可专家组成员Michael D. Jensen, MD, Co-ChairDonna H. Ryan, MD, Co-ChairCaroline M. Apovian, MD, FACP Catherine M. Loria, PhD, FAHA*Jamy D. Ard, MD Barbara E. Millen, DrPH, RD Anthony G. Comuzzie, PhD Cathy A. Nonas, MS, RD Karen A. Donato, SM* F. Xavier Pi-Sunyer, MD,MPHFrank B. Hu, MD, PhD,FAHAJune Stevens, PhDVan S. Hubbard, MD, PhD*Victor J. Stevens, PhD John M. Jakicic, PhD Thomas A. Wadden, PhD Robert F. Kushner, MD Bruce M. Wolfe, MD Susan Z. Yanovski, MD*方法学成员Harmon S. Jordan, ScDKarima A. Kendall, PhDLinda J. LuxRoycelynn Mentor-Marcel, PhD,MPHLaura C. Morgan, MAMichael G. Trisolini, PhD, MBAJanusz Wnek, PhDACCF/AHA专责组成员Jeffrey L. Anderson, MD, FACC, FAHA, ChairJonathan L. Halperin, MD, FACC, FAHA, Chair-ElectNancy M. Albert, PhD, CCNS, CCRN, FAHA Judith S. Hochman, MD, FACC, FAHABiykem Bozkurt, MD, PhD, FACC, FAHA Richard J. Kovacs, MD, FACC, FAHARalph G. Brindis, MD, MPH, MACC E. Magnus Ohman, MD, FACC Lesley H. Curtis, PhD, FAHA Susan J. Pressler, PhD, RN, FAAN,FAHADavid DeMets, PhD Frank W. Sellke, MD, FACC, FAHA Robert A. Guyton, MD, FACC Win-Kuang Shen, MD, FACC, FAHA预防指南分会Sidney C. Smith, Jr, MD, FACC, FAHA, ChairGordon F. Tomaselli, MD, FACC, FAHA, Co-Chair*当然委员。
3．2 研究工具3.2.1 大五人格问卷简版（NEO-FFI）该问卷是Costa和McCrae在对1985年版本的NEO-PI-R进行项目因素分析的基3.2.2 绩效考核成绩从上表可以看出，戴德梁行客户经理群体在谨慎性维度上的得分最高，其次分别是外向性、友善性、开放性，得分最低的维度是神经质。
4.1.2 该行客户经理在大五人格各维度上的性别差异如上表，大五人格五个维度的性别差异在开放性维度上显著性最高（p<0.001），男性的开放性显著高于女性；其次在外向性、谨慎性两个维度上差异也较为显著（p<0.01），具体表现为男性的外向性、谨慎性均高于女性。
由表可知，大五人格中神经质维度对任务绩效有显著的负预测性，能解释总体的变异。
在进行了三次回归分析后，大五人格中的开放性、友善性、外向性三个维度都进入了回归模型，切模型的总体回归效果显著。
这三个维度共解释了情境绩效 4%的变异。
通过进一步分析这三个维度逐步进入回归模型的顺序可以得知，Figure 4: model of confirmatory factory analysis注：Extraver=外向性，Agreeabl=亲和力，Conscien=责任心，Neurotic=情绪稳定性，Openness=开明性。
LISREL 软件输出了这一模型同数据的具体拟合指标如下。
模型的卡方Chi-squares）为109.96，自由度（degree of freedom, df）为80，因此方值和自由度的比（Chi-squares/df）为109.96/80=1.37，小于 5 这一临界值水平（这一指标越小表示模型与数据的拟合情况越好）。
模型的比较拟合指数（comparative fit index, CFI）为0.89、非正态拟合指数（non-normed fit index, NNFI）为0.86，虽然没有达到.90之上，但由于比较接近，我们认为都处于可接受范围之内。
DPPH法测定胡萝⼘素的抗氧化活性⽬录摘要 ....................................................................................................................................... - 1 - Abstract .................................................................................................................................. - 2 - 第⼀章绪论................................................................................................... - 3 -1.1 果蔬的主要抗氧化活性物质 ................................................................................. - 3 -1.1.1 茄红素 ........................................................................................................... - 3 -1.1.2 类黄酮 ........................................................................................................... - 3 -1.1.3 花青素 ........................................................................................................... - 4 -1.2 果蔬抗氧化作⽤机理 ............................................................................................. - 4 -1.3 果蔬抗氧化活性的评价⽅法 ................................................................................. - 5 -1.3.1 Rancimat法对果蔬提取物进⾏抗氧化活性研究........................................ - 5 -1.3.2 β-胡萝⼘素-亚油酸乳化液氧化法 ............................................................... - 5 -1.3.3 ⼆苯代苦味酰基⾃由基(DPPH·)法............................................................. - 6 -1.3.4 硫代巴⽐妥酸反应物(TBAS)值法 .............................................................. - 7 -1.3.5 FRAP(ferric reducing/antiox idant power assay)法 ....................................... - 7 -1.4 本研究的意义和内容 ............................................................................................. - 7 -1.4.1 本研究的意义 ............................................................................................... - 7 -1.4.2 本研究的内容 ............................................................................................... - 8 - 第⼆章实验材料和内容............................................................................... - 9 -2.1 材料与仪器 ............................................................................................................. - 9 -2.1.1 实验材料 ....................................................................................................... - 9 -2.1.2 实验仪器 ....................................................................................................... - 9 -2.1.3 试剂 ............................................................................................................... - 9 -2.2 实验内容 ................................................................................................................. - 9 -2.2.1 胡萝⼘素的提取 ........................................................................................... - 9 -2.2.2 在DPPH体系中测定抗氧化性................................................................. - 10 - 第三章实验结果与讨论............................................................................. - 12 -3.1 胡萝⼘素提取液的抗氧化性 ............................................................................... - 12 -3.2 β-胡萝⼘素的抗氧化性......................................................................................... - 12 -3.3 茶多酚的抗氧化性 ............................................................................................... - 13 -3.4 维⽣素C的抗氧化性 .......................................................................................... - 14 -3.5 维⽣素E的抗氧化性........................................................................................... - 15 - 第四章结论................................................................................................. - 17 - 展望............................................................................................................................. - 18 - 参考⽂献............................................................................................................................. - 19 - 致谢............................................................................................................................. - 21 - 附录............................................................................................................................. - 22 -DPPH法测定胡萝⼘素的抗氧化活性摘要：胡萝⼘中含有⼤量的β-胡萝⼘素，摄⼊⼈体消化器官后，可以转化成维⽣素A，是⽬前最安全补充维⽣素A的产品。
摘要伴随着世界经济和金融形势的变化，外汇汇率这一作为国际金融关系乃至是国际经济关系正常发展的纽带，己经渗透到包括经济生活的一切领域，我国各涉外单位尤其是外贸企业，正越来越强烈地感知到外汇风险所带来的巨大影响。
因此，分析外汇风险带给我国外贸企业的影响以及企业当前所面临的各种外汇风险，并找出相应的风险管理防范措施，有效地规避风险具有重大的理论和现实意义。
、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、本文主要采用理论和案例研究的方法研究我国外贸企业外汇风险管理。
第一，本文对外汇风险理论进行了系统的阐述，认为我国的外汇风险主要是由人民币汇率变动带来的，并将外贸企业的外汇风险主要划分为三大类：交易风险、会计风险和经济风险。
第二，本文通过回顾我国汇率制度的变化，发现我国外贸企业的外汇风险是伴随着几十年来我国汇率制度的改革推进而逐步产生的。
作者在回顾我国各时期的汇率制度、以及分析人民币汇率风险现状的基础上，从不同的角度探究汇率变动对外贸企业的影响。
第三，本文通过分析我国外汇企业的外汇风险管理现状与不足，尤其对不足之处展开了论述，引出我国外贸企业如何管理其外汇风险。
作者认为汇率的变动是导致外贸企业外汇风险的罪魁祸首，所以对汇率走势的判断是进行一切外汇风险管理的基础。
在对人民币未来汇率走势判断的基础上，本文根据外汇风险的不同分类、不同的宏微观角度、针对外汇风险管理现存的问题，分别提出相应的外汇风险管理应对措施，以供外贸企业进行多角度的选择风险管理策略。
最后，本文结论为我国外贸企业在防范外汇风险过程中面临的一些主客观问题还有待进一步研究解决，为此，本文也提出建议，要从多方面努力营造风险防范的环境，我国外贸企业应首先立足于自我防范，积极研究和使用各种防范措施，达到提高外贸企业风险管理水平的目的。
关健词：外汇风险管理，外贸企业，人民币汇率，金融避险工具目录第1 章. 绪论 (1)1.1 选题背景 (1)1.2 研究现状 (2)1.2.1 国外情况 (2)1.2.2 国内情况 (3)1.3 研究方法与创新之处 (4)第2 章. 外汇风险相关理论概述 (6)2.1 外汇风险概念 (6)2.2 外汇风险的构成及特点 (6)2.3.外汇风险产生的原因 (6)2.4 外汇风险的种类 (7)2.4.1 交易风险 (8)2.4.2 经济风险 (8)2.4.3 会计风险 (8)第3 章. 不同汇率制度下的外汇风险对我国外贸企业的影响 (9)3.1 我国的汇率制度 (9)3.1.1 2005 年汇率改革前人民币汇率制度 (9)3.1.2 我国现行汇率制度 (10)3.2 人民币汇率风险的现状 (10)3.2.1 人民币兑美元汇率风险 (10)3.2.2 人民币兑其他主要货币汇率风险 (11)3.3 汇率变动如何对外贸企业产生影响 (11)3.3.1 对进出口总体的影响 (12)3.3.2 对不同贸易方式的影响 (12)3.3.3 对不同企业类型的影响 (13)3.3.4 对不同产品类型的影响 (14)第4 章. 我国外贸企业外汇风险管理中存在的主要问题 (16)4.1 总体现况 (16)4.2 风险防范意识较薄弱 (17)4.3 外汇风险防范专业人才储备不足 (18)4.4 缺少完善的外汇风险管理战略 (18)4.5 风险管理的机制不明确 (19)4.6 避险金触工具的运用单一 (19)第5 章. 我国外贸企业提高外汇风险管理水平的对策研究 (20)5.1 人民币汇率走势的判断 (20)5.1.1 人民币对美元汇率历史走势 (20)5.1.2 次贷危机对美元汇率走势的影响 (21)5.1.3 人民币汇率的走势预测 (22)5.2 根据外汇风险的不同分类进行管理 (23)5.2.1 交易风险的管理 (23)5.2.2 会计风险的管理 (30)5.2.3 经济风险的管理 (32)5.3 从宏微观角度出发的外汇风险管理 (33)5.3.1 宏观角度 (34)5.3.2 微观角度 (35)5.4 针对现状不足的外汇风险管理 (36)5.4.1 增强外汇风险防范意识 (36)5.4.2 加强外汇风险防范专业人才储备 (37)5.4.3 完善自身的外汇风险管理战略 (38)5.4.4 完善风险防范的监控机制 (38)5.4.5 尝试使用多种避险金融工具 (39)结论与展望 (42)参考文献 (43)1第1 章. 绪论1.1 选题背景伴随着世界经济和金融形势的变化，外汇汇率这一作为国际金融关系乃至是国际经济关系正常发展的纽带，己经渗透到包括经济生活的一切领域，我国各涉外单位尤其是外贸企业，正越来越强烈地感知到外汇风险所带来的巨大影响。
