Constructive Negation and Constraints
Roman Barták*
Department of Theoretical Computer Science, Charles University
Malostranské nám. 2/25, Praha 1, Czech Republic
e-mail: bartak@kti.mff.cuni.cz
URL: http://kti.ms.mff.cuni.cz/~bartak/
phone: +420-2 2191 4242
fax: +420-2 2191 4323
Abstract: Inclusion of negation into logic programs is considered
traditionally to be painful as the incorporation of full logic negation tends
to super-exponential time complexity of the prover. Therefore the
alternative approaches to negation in logic programs are studied and among
them, the procedural negation as failure sounds to be the most successful
and the most widely used. However, Constraint Logic Programming (CLP)
is offering a different approach called constructive negation, that is
becoming more popular.
In this paper we present a constructive approach to negation in logic
programs. We concentrate on implementation aspects of constructive
negation here, i.e., on the design of CLP(H) system, where H is the
Herbrand Universe.
Keywords: constructive negation, logic programming, constraints, CLP
1 Introduction
Logic programming, i.e., programming using definite clauses, does not allow negated goals in the bodies of clauses. Also, it is known that incorporation of full logic negation tends to super-exponential complexity of the prover. However, the inclusion of some form of negation is required from the programming point of view and, thus, the alternative approaches, mostly based on Reiter's Closed World Assumption originated in databases, have been proposed.
Currently the most successful approach to negation in logic programming is procedural negation as failure which is also a part of ISO standard of Prolog. The operational behaviour of this form of negation can be easily described by the following Prolog program:
not P:-P,!,fail.
not P.
The advantages of the negation as failure, or more precisely, the negation as finite failure, make it attractive especially from the programming point of view. It uses sub-derivations to determine negative goals, thus exploiting the efficiency of the underlying logic programming system, and handling “special” features of the * Partially supported by the Grant Agency of Czech Republic under the contract No 201/96/0197.
language, e.g., cut. However, the procedural negation as failure is known to have two important drawbacks: it can be used safely on ground subgoals, and on some particular types of non-ground goals, and it cannot generate any new bindings for query variables.
To overcome the above mentioned drawbacks of negation as failure Chan [4] introduced a new concept of constructive negation that extends the negation as failure to handle non-ground negative subgoals in a constructive manner. Its name stresses the fact that this form of negation is capable of constructing new bindings for query variables.The constructive negation scheme inherits many of the advantages of negation as failure, in particular it exploits the efficiency of the underlying logic programming system, and it handles special features of the language as well. At the same time, it removes the main drawbacks of negation as failure because constructive negation can handle non-ground negative subgoals and generates new bindings for query variables.
In [12] Stuckey proposed Constraint Logic Programming (CLP) as a much more natural framework for describing constructive negation. The CLP framework was developed in [5,7] and it is counted to be the lifesaver of logic programming for real-life applications. In CLP(A) scheme, the Herbrand Universe is displaced by a particular structure A which determines the meaning of the functions and (constraint) relation symbols of the language. The constraint viewpoint of constraint logic programming is well matched with constructive negation. Not only is constructive negation easier to understand from this point view, but it gives the clean approach to negation in constraint logic programming as well. More information on CLP can be found in [3,6,7,13].
In this paper we concentrate on the implementation aspects of constructive negation. In fact, we are interested in efficient implementation of the CLP(H) scheme where H is the Herbrand Universe with equality and disequality constraints. We design the constraint solver for solving equalities and disequalities over the Herbrand Universe and we propose a filtering system to obtain relevant solutions. The combination of the constraint solver with the filtering system enables us to implement efficiently the constructive negation. The resulting system handles negation in a more natural way which was the primary goal of this work. To justify our approach, we have implemented the ideas from this paper in two software prototypes.
The paper is organized as follows. In Section 2 we give motivation of this work. In Section 3 we discuss briefly the constraint solving over the Herbrand Universe, in particular solving equalities and disequalities and filtering the acquired solution. We devote Section 4 to the practical aspects of implementation of the constructive negation. In Section 5 we give some examples to compare the negation as failure with the concept of constructive negation. We argue for constructive negation here as it returns more natural solutions and preserves the declarative character of logic programs. In Section 7 we briefly describe two software prototypes implementing constructive negation. We conclude with some final remarks and description of future research.
2 Motivation
The procedural negation as finite failure serves very well if applied to ground goals but as soon as non-ground goals appear the results are disappointing. A rather extensive literature related to this topic documents that the drawbacks of the negation as failure tend to behaviour that corrupts the declarative character of logic programs as the following example shows.
Example:
Let P be the following program:
u(a).
v(a).
v(c).
Now, if we solve the goal ?-not u(X),v(X) using the program P and the ordinary negation as failure, we get the answer no. However, if the goal ?-v(X),not u(X) is solved, the solution is X=c. Note, that the only difference between above two goals is the order of atomic goals so the declarative character, and thus the solution, of the goals should be the same.
The above example shows that if the negation as failure is used with non-ground goals, it could return non-intuitive solutions (for other examples see Section 5). To avoid such non-intuitive behaviour and to keep the declarative character of logic programs we shift our attention to the constructive negation which promises to handle even the non-ground negative goals correctly. However, neither the pioneering works on constructive negation [11,12] nor the recent works on CLP [3,6] provide enough details to a successful implementation of the concept of constructive negation.
3 Constraint Solving over the Herbrand Universe
The traditional drawback of logic programms and Prolog is that they cannot handle negative information in a constructive way, i.e., the disequality X≠Y can be used as a test only. Because presence of disequalities is strongly desirable in the constructive negation approach we choose the CLP(H), where H is the Herbrand Universe with equality and disequality constraints, as a natural framework for understanding and implementing constructive negation. Solving equalities displaces naturally unification there, while disequalities can appear as a result of negating the solution of the goal. Of course, there are no difficulties to allow presence of equalities and disequalities in goals and in bodies of clauses as well.
The nature of equalities and disequalities in the Herbrand Universe enables us to implement two relatively independent components of the constraint solver, the component processing equalities and the other component processing disequalities. The cooperation between these two components is following: if the component responsible for equality solving resolves successfully the set of equalities then the result, i.e., the valuation of variables, is applied to the set of disequalities and the resulting disequalities are solved in the other component of the solver. It can be shown that if any of the components fails then the system of equalities and
disequalities is inconsistent. Just note, that there is no need to iterate this process as the solution of disequalities does not further influence the solution of equalities.
The easier part of the constraint solver is processing equalities as it corresponds directly to the unification which is well understood [8]. To grasp formally the process of equality solving, in [2] we introduce a normal form for system of equalities that is a conjuction of equalities in the form x=t, where x is a variable and t is a term. Then, each system of equalities can be solved by transforming to the normal form or it is found to be inconsistent.
Similarly, in [2] we define the normal form for disequality that is [x i]≠[t i] where [x i] is a list of variables and [t i] is a list of terms. Note, that the normal form corresponds to the disjunction of simple disequalities x i≠t i. Again, each system of disequalities can be solved by transforming to the normal form or it is found to be inconsistent. To simplify the system of disequalities, in [2] we define the subsumption relation between diseaqualities whose application removes some unneeded disequalities in the conjunction of disequalities, e.g., X≠a subsumes f(X,b)≠f(a,X).
Example:
initial system of disequalities: X≠a & f(X,Y,a)≠f(a,b,X) & h(Y,k(X))≠h(b,g(X)) the normal form: [X]≠[a]
(because f(X,Y,a)≠f(a,b,X) is subsumed by X≠a and h(Y,k(X))≠h(b,g(X)) is
a valid disequality)
In [2], we describe the algorithms for solving equalities and disequalities by transforming them into normal form. These algorithms makes the basic constraint solver in the CLP(H) system.
To complete the construction of the CLP(H) system, there remains to answer the following question:
What should be presented to the user of the system as the result of computation? The obvious extreme answers to the above question, i.e. nothing (yes/no answer) or everything (all equalities and disequalities), are not suitable from the point of view of constructive negation [2]. Also, the approach of most Prolog systems, which return relevant (to the goal) equalities only, is not appropriate for constructive negation because the negative information is lost (see examples in Section 5).
The result of above discussion is that relevant equalities and disequalities should be returned as the solution of the goal. We call the process of selecting the relevant equalities and disequalities filtering solution. First, the equalities relevant to the variables in the goal are selected and, then, the disequalities relevant to the variables in both the goal and the relevant equalities are selected. This is a novel approach to the definition of relevance which approved to return intutive answers as the following example shows.
Example:
Let P be the following CLP(H) program:
p(a).
p(f(Y,Z)):-q(Y),Z≠c,U≠d.
q(b).
The following schema captures the course of computation of the goal ?-X≠a,p(X) using the program P. During the computation, the satisfiable but not valid disequalities are collected to prune the further computation as you can see at the left part of the schema which shows the course of computation.
We also label this part by equalities solved and by clauses used to reduce the goal. To simplify the figure, we encapsulate the standardization apart. The right part of the scheme represents the subsequent filtering of the computed solution which is displayed bellow the schema.
≠c,U≠d.
X=f(b,Z),Y=b,Z≠c,U≠d
4 How to Negate the Solution?
By implementing CLP(H), where H is the Herbrand Universe with equality and disequality constraints, we get the ideal framework for constructive negation. What remains is to implement the concept of constructive negation itself.
The constructive negation is based on the following procedure:
1. take a negative subgoal,
2. run the positive version of this subgoal,
3. collect all solutions of this possibly non-ground subgoal as a disjunction,
4. negate the disjunction giving a formula equivalent to the negative subgoal. Steps 1, 2 and 3 are handled naturally by the underlying inference machine, so we have to describe only how the collected solution of the positive version of the goal is negated. Remind that the solution of the goal is a conjunction of equalities and disequalities in normal form relevant to the goal. We call such solution a single solution. For the constructive negation one needs to collect all single solutions of the positive version of the goal (step 3 above), so the disjunction of single solutions is constructed. We call such solution a complete solution. This is different from the
negation as finite failure, where the existence of a single solution for the positive version of the goal implies immediately the failure of negative goal. We will discuss the efficiency of finding the complete solution later in this section.
Now, the question is how to negate the complete solution? We rely on the following formula [12] which is a property of the Herbrand Universe:
( ??Y,Z (x=t & Q) ) ? ( ?Y (x≠t) ∨?Y (x=t & ??Z Q) )(1)
where x is a variable that does not appear neither in t nor in Q, Y is the set of variables in t (i.e., Y=vars(t)) and Z is the set of variables which appear in Q but not in t (i.e., Z=vars(Q)—Y).
The semantic meaning of the formula (1) is the following: if one uses some clause H:-B to solve the positive goal ?-G and then negates the obtained solution to get a solution of the goal ?-not G then there are two alternatives:
(i) the clause H:-B is prevented to be used for reduction of G by disabling
unification of G and H (i.e., G≠H), or
(ii) the clause H:-B is used for reduction of the goal G, i.e., G=H, but the solution of B is negated.
These two cases correspond roughly to two elements of the disjunction in formula (1).
The following example explains the process of finding the solution of negative goal (for simplification we omit the quantifiers).
Example:
Let P be the program:
p(a).
p(f(Y)):-Y≠b.
and the goal to solve be: ?-not p(X).
1) Run positive version of the goal:?-p(X).
2) Collect complete solution:X=a ∨ (X=f(Y) & Y≠b)
3) Negate the complete solution:X≠a & (X≠f(Y) ∨ (X=f(Y) & Y=b))
4) Convert to DNF and simplify:(X≠a & X≠f(Y)) ∨ X=f(b)
i.e. ?Y (X≠a & X≠f(Y)) ∨?Y (X=f(b) &
Y=b)
Note, that if we negate the acquired complete solution “mechanically”, i.e.,
without application of the above formula (1), we get the wrong solution
(X≠a & X≠f(Y)) ∨ (X≠a & Y=b).
At the beginning of this section, we mentioned that finding a complete solution of the positive version of the goal can be the source of some inefficiency comparing to the negation as failure. In general, this is true but the additional information in disequalities can be exploited to prune the computational tree which subsequently speeds up the interpreter.
When a negated goal is solved, all equalities and disequalities currently collected are “frozen” and passed to the interpreter which is finding the complete solution of the positive version of the goal. This “frozen information” is used to prune the
computational tree but, as the equalities and disequalities are frozen, they are not returned in the solution (and thus negated) as the following example shows. Example:
Let procedure p be defined by the following two clauses:
p(a):-… % arbitrary body here
p(b).
If one solves the goal ?-X≠a,not p(X), the frozen disequality X≠a is passed to the solver when the complete solution of the goal ?-p(X) is being computed. This prunes the computational tree, i.e., the clause p(a):-… is not used to reduce the goal ?-p(X), and the complete solution X=b is returned.
After negation and joining with the frozen disequality X≠a the solution X≠a,X≠b of the original goal is found.
5 Examples
The original goal of this work was to implement a negation in logic programs in such a way that more intuitive solutions are produced and the declarative character of the program is preserved. The following table shows a bundle of examples and a comparison of solutions produced by the standard negation as finite failure (NF) and by our implementation of constructive negation respectively. In the “constructive negation column”, the alternative solutions of the goal are depicted as individual rows.
SOLUTION PROGRAM GOAL NF CONSTRUCTIVE
NEGATION
?-p(X).no X=f(Y) & Y≠a
p(f(Y)):-not q(Y).?-not p(X).yes X≠f(Y)
q(a).X=f(a)
?-not not p(X).no X=f(Y) & Y≠a
s(f(Y)):-not r(Y).?-s(X).no no
r(Z).?-not s(X).yes no
p(a,f(Z)):-t(Z).?-not p(X,Y).no X≠a & X≠f(c)
p(f(Z),b):-t(Z).X≠f(c) & Y≠f(c)
t(c).X≠a & Y≠b
Y≠f(c) & Y≠b
u(a).?-not(u(X),v(X)).no X≠a
u(b).?-not u(X), not v(X).no X≠a & X≠b & X≠c
v(a).?-not u(X), v(X).no X=c
v(c).?-v(X), not u(X).X=c X=c
Comparison - Negation as Failure vs. Constructive Negation
6 Implementation
To test ideas described in this paper we have implemented two software prototypes in Prolog based on concepts of meta-interpretation and meta-variables respectively.
Because the implementation of CLP(H) requires changes of the inference machine of Prolog, we use a standard technique called meta-interpretation first. We utilize the concept of extendible meta-interpreter which we proposed in our previous papers [1]. Extendible meta-interpreter is a meta-interpreter whose functionality can be extended via plug-in modules. We have implemented the constraint solver and the solution filter as such plug-in modules. The advantage of using meta-intepreters to change the standard behaviour of Prolog is that the original program and goal need not be changed. The main disadvantage of meta-intepreters is the slow down of the computation.
The second implementation utilizes the concept of meta-variables [10] and open architecture of Prolog [9]. Meta-variables are a way to extend Prolog’s built-in unification by user definitions. First, we implemented a library that can be attached to arbitrary Prolog program to add functionality of meta-variables. Then, we redefined standard unification using the meta-variable concept, we implemented a disequality solver and we added a constructive negation construct cnot. The advantage of this approach is that the underlying Prolog interpreter is exploited as much as possible and thus the efficiency is preserved. The little drawback of this approach is that the original program and the goal have to be rewritten to use the “changed” unification and cnot construct.
The Prolog source code of both implementations is available on-line at URL: http://kti.ms.mff.cuni.cz/~bartak/html/negation.html.
7 Conclusions
In this paper we present a complete implementation of the constructive negation within the CLP(H) framework, where H is the Herbrand Universe with equality and disequality constraints. We design the constraint solver for solving equalities and disequalities over the Herbrand Universe and we also propose a filtering system to obtain relevant solutions. Finally, we exploit the foundation of CLP(H) to implement naturally the constructive negation. We also highlight some problems which appear during the implementation and we propose the solution of these problems.
We strongly argue for using constructive negation here as it provides more natural results than the widely used negation as failure. Also, we show that the constructive negation preserves better the declarative character of logic programs. By implementing the proposed CLP(H) system we prove that it is possible to incorporate constructive negation efficiently.
There is still a lot of opportunities for further research. Very interesting area is incorporation of constructive negation into CLP(A) over arbitrary domain A or into Hierarchical CLP (HCLP). Both CLP and HCLP are important from the point of view of real-life applications.
The main contribution of this work is that it shows a real implementation of constructive negation supported by the underlying theory. Acknowledgments
I would like to thank professor Petr ·t?pánek for his continuous support, useful discussions and comments on prerelease version of the paper.
References
[1]Barták, R. and ·t?pánek, P., Extendible Meta-Interpreters, KYBERNETIKA,
Volume 33(1997), Number 3, pp. 291-310
[2]Barták, R., Constructive Negation in CLP(H), submitted to CP'98 conference
[3]Benhamou, F. and Colmerauer, A. (eds.), Constraint Logic Programming-
Selected Research, The MIT Press, Cambridge, Massachusetts, 1993
[4]Chan, D., Constructive Negation Based on Completed Database, in:
Proceedings of 5th International Conference on Logic Programming, Seattle,
1988, pp. 111-125
[5]Gallaire, H., Logic programming: Further developments, in: IEEE Symposium
on Logic Programming, pp. 88-99, IEEE, Boston, July 1985
[6]Jaffar, J., Maher, M.J., Constraint Logic Programming: A Survey, in: Journal
of Logic Programming 19, pp. 503-581, 1994
[7]Jaffar, J., Lassez, J.-L., Constraint Logic Programming, in: Proceedings of the
14th ACM Symposium on Principles of Programming Languages, pp. 111-
119, Munich, Germany, January 1987
[8]Lloyd, J.W., Foundations of Logic Programming, Springer-Verlag, Berlin,
1984
[9]Meier, M., Schimpf, J., An Architecture for Prolog Extensions, TR ECRC-95-
6, ECRC, 1995
[10]Neumerkel, U., Extensible Unification by Metastructures, in: Proceedings of
META`90, 1990
[11]Przymusinsky, T. C., On Constructive Negation in Logic Programming,
Extended Abstract, 1991
[12]Stuckey, P. J., Constructive Negation for Constraint Logic Programming, in:
Proceedings of Logic in Computer Science Conference, 1991, pp. 328-339 [13]Van Hentenryck, P., Constraint Satisfaction in Logic Programming, Logic
Programming Series, The MIT Press, 1989
一．一．用反面表达法处理下列各句中的斜体动词： 1. 1.The ache that had persisted in his chest had turned to severe pain. 2. 2.“If we lose our lives, then you’ll lose yours!” she said with a laugh. 3. 3.If he had kept his temper, the negotiation would probably have been a success. 4. 4.The two teams tied. 二．二．用反面表达法处理下列各句中的斜形容词： 1. 1.Appearances are deceptive. 2. 2.The teacher found some of the pupils absent. 3. 3.Her face had a strange, lost look. 4. 4.I’m terribly sorry to have given you such a lot of trouble. 三．三．用反面表达法处理下列各句中的斜前置词： 1. 1.But that’s very extraordinary. It seems against nature. 2. 2.Never mind, we can manage without help. 3. 3.His answer is beside the mark. 4. 4.Under fifty people were there. 四．四．用反面表达法处理下列各句中的斜体名词： 1. 1.Her abstraction was not because of the tea party. 2. 2.He did not want to hurt her, but an itch to dominate push him on to say… 3. 3.Silence reigned all over for a while. 五．五．用反面表达法处理下列各句中的斜体副词： 1. 1.He said idly,“Well, what does it matter?” 2. 2.They resumed their seats moodily. 3. 3.She always seemed too busy in the house. 4. 4.Slowly he pulled the letter out of the envelope, and unfolded it. 六．六．用反面表达法处理下列各句中的斜体连接词： 1. 1.The stranger had already gone before he hurried to the hotel. 2. 2.She couldn’t sit still till her native country was free. 3. 3.They would rather have the blue one than the green one. 4. 4.You will fail unless you work harder. 七．七．用反面表达法处理下列各句中的斜体短语： 1. 1.You should seize the opportune moment to put in a word for me. 2. 2.The news of the assassination of President Lincoln spread like wild fire. 3. 3.The pioneers made light of difficulties and dangers. 4. 4.Miss Firelie kept to her room all day. 八．八．用反面表达法处理下列各句中的斜体从句或句子： 1. 1.As was expected, the enemy walked right into the trap. 2. 2.It had been six or seven hours since I had had anything to eat, drink or smoke. 3. 3.Mr. Will was a short and skinny white man with dark hair and gray eyes, a smile that seemed to be frozen on his face and everybody knew it was anything else but a genuine smile. 九. 试译下列各句，用正面表达法处理斜体部分： 1. For him the wheel of slumber was wont to turn noiseless and slick and swift. 2. Generally she accepted the family life in all its crowded inadequacy. 3. Jim was no end upset because he couldn’t go swimming. 4. Sir Percival’s spies were not going to lose sight of me.
【学英语必看】 《英语语法手册》 在实用英语备受青睐的现在，大家在学习英语和准备各种考试时，总是把 听说读写放在首位，诚然，学习语言重在实践。但是，请不要忽视语法的作用，特别是在阅读和写作中，他能帮助你分析清楚句子结构，准确抓住句子的要点，更能帮你写出复杂而优美的长句。 以下为你整理《英语语法手册》全集，不需背诵记忆，只要静下心阅读一遍，就能有所收获！ 宝宝更希望你能把他们融在平时的阅读写作里. [英语语法手册]关于词类和句子成分 根据词的形式、意义及其在句中的功用将词分为若干类，叫做词类。一个 句子由各个功用不同的部分所构成，这些部分叫做句子成分。 学一个词，要学它的发音、拼法、意义，也要记它的词类；更重要的是要 了解它和其他词的关系，及其在句中作什么句子成分。如China is in East Asia(中国位于东亚)一句中的China这个单词所属的词类是名词，在句子中作主语。 词类(parts of speech) 英语的词通常分为十大类： 1）名词(noun，缩写为n.)是人和事物的名称，如pen(钢笔)，English(英语)，life(生活)。 2)代词(pronoun，缩写为pron.)是用来代替名词的词，如we(我们)，his(他的)，all(全部)。 3)形容词(adjective，缩写为adj.)用来修饰名词，如great(伟大的)，honest(诚实的)，difficult(困难的)。 4)数词(numeral，缩写为num.)是表示"多少"和"第几"的词，如four(四)，eighteen(十八)，first(第一)，eighth(十八)，hundred(一百)。
脐带间充质干细胞的研究进展 间充质干细胞（mesenchymal stem cells,MSC S ）是来源于发育早期中胚层 的一类多能干细胞[1-5]，MSC S 由于它的自我更新和多项分化潜能，而具有巨大的 治疗价值 ,日益受到关注。MSC S 有以下特点：(1)多向分化潜能，在适当的诱导条件下可分化为肌细胞[2]、成骨细胞[3、4]、脂肪细胞、神经细胞[9]、肝细胞[6]、心肌细胞[10]和表皮细胞[11, 12]；(2)通过分泌可溶性因子和转分化促进创面愈合；(3) 免疫调控功能，骨髓源（bone marrow ）MSC S 表达MHC-I类分子，不表达MHC-II 类分子，不表达CD80、CD86、CD40等协同刺激分子，体外抑制混合淋巴细胞反应，体内诱导免疫耐受[11, 15]，在预防和治疗移植物抗宿主病、诱导器官移植免疫耐受等领域有较好的应用前景；(4)连续传代培养和冷冻保存后仍具有多向分化潜能，可作为理想的种子细胞用于组织工程和细胞替代治疗。1974年Friedenstein [16] 首先证明了骨髓中存在MSC S ，以后的研究证明MSC S 不仅存在于骨髓中，也存在 于其他一些组织与器官的间质中：如外周血[17]，脐血[5]，松质骨[1, 18]，脂肪组织[1]，滑膜[18]和脐带。在所有这些来源中，脐血(umbilical cord blood)和脐带(umbilical cord)是MSC S 最理想的来源，因为它们可以通过非侵入性手段容易获 得，并且病毒污染的风险低，还可冷冻保存后行自体移植。然而，脐血MSC的培养成功率不高[19, 23-24]，Shetty 的研究认为只有6%，而脐带MSC的培养成功率可 达100%[25]。另外从脐血中分离MSC S ，就浪费了其中的造血干/祖细胞(hematopoietic stem cells/hematopoietic progenitor cells,HSCs/HPCs) [26, 27]，因此，脐带MSC S (umbilical cord mesenchymal stem cells, UC-MSC S )就成 为重要来源。 一．概述 人脐带约40 g, 它的长度约60–65 cm, 足月脐带的平均直径约1.5 cm[28, 29]。脐带被覆着鳞状上皮，叫脐带上皮，是单层或复层结构，这层上皮由羊膜延续过来[30, 31]。脐带的内部是两根动脉和一根静脉，血管之间是粘液样的结缔组织，叫做沃顿胶质，充当血管外膜的功能。脐带中无毛细血管和淋巴系统。沃顿胶质的网状系统是糖蛋白微纤维和胶原纤维。沃顿胶质中最多的葡萄糖胺聚糖是透明质酸，它是包绕在成纤维样细胞和胶原纤维周围的并维持脐带形状的水合凝胶，使脐带免受挤压。沃顿胶质的基质细胞是成纤维样细胞[32]，这种中间丝蛋白表达于间充质来源的细胞如成纤维细胞的，而不表达于平滑肌细胞。共表达波形蛋白和索蛋白提示这些细胞本质上肌纤维母细胞。 脐带基质细胞也是一种具有多能干细胞特点的细胞，具有多项分化潜能，其 形态和生物学特点与骨髓源性MSC S 相似[5, 20, 21, 38, 46]，但脐带MSC S 更原始，是介 于成体干细胞和胚胎干细胞之间的一种干细胞，表达Oct-4, Sox-2和Nanog等多
【翻译技巧】英语笔译技法——正反译法 由于国家、历史、地理、社会文化背景和生活习性的不同，汉英两种语言在表达正说和反说时有很大差异，尤其英语在否定意义的表达上更为复杂，有时形式否定而实质肯定，或形式肯定而实质否定。在两种语言互译时，原文中正说的句子可能不得不处理成反说，或是用反说表达更为合适。反之亦然。翻译中，这种把正说处理成反说、把反说处理成正说的译法，就称为正反译法。 正反译法是翻译技巧中的一个重要方法，属于引申和修辞范围。 笼统的说，英语句子中含有“never”、“no”、“not”、“un-”、“im-”、“in-”、“ir-”、“-less”等否定词以及否定前缀或后缀的单词，以及汉语句子中含有“不”、“没”、“无”、“未”、“甭”、“别”、“休”、“莫”、“非”、“勿”、“毋”等否定词的即为反说，不含有这些否定词的即为正说。 但实际操作时，正说和反说的界限又变得极为模糊，例如“correct”可以翻译成“正确”（正说），也可以翻译成“没有毛病”（反说）。因此，到底译文要采用正说还是反说，就完全要看译文语言的惯用表达和上下文的语气语态了。 在正反译法中，英译汉正转反（正说反译法）和汉译英反转正（反说正译法）是最为重要的两种正反译法。 英译汉正转反 英语中有些否定概念是通过含有否定意义或近似否定意义的词来表达的，虽然形式是肯定的，但这类词大多是某些肯定词所引申或变化出来的反义词，或经过长期历史演变而引申出其他否定词义，即所谓的“含蓄否定词”或“暗指否定词”，这类词在译成汉语时，需要变成汉语的否定词组，必要时还需要作词类转换。 1、名词 —含蓄否定名词主要有：shortness / shortage（不够；不足）、lack（缺乏；没有）、absence （不在）、failure（未能；不成功）、defiance（不顾；无视）、denial（否认；否定）、exclusion （排除）、freedom（不；免除）、refusal（不愿；不允许）、loss（失去）等。 Shortness of time has required the omission of some states. 由于时间不够，没能访问那些国家。 Behave yourself during my absence. 我不在时要规矩点。 We were perplexed by his failure to answer the letter. 他何以不回信，我们大惑不解。 2、动词或动词短语 —英语中常见的含蓄否定动词包括：refuse（不愿；不肯；无法）、lack（缺乏；没有）、defy（不服从；不遵守；不让）、forbid（不许）、stop（不准；别）、ignore（不理；不肯考虑；无视；不顾）、hate（不愿意）、miss（没听清楚；没赶上）等。
正反译法练习之一 1.The newspaper accounts are far from being true. 报纸上的报道一点儿也不真实。 2.Mr. Thompson was above reproach. 汤姆森先生的行为是无可非议的。 3.Keep dry and the top side up! 请勿倒立，防止受潮！ 4.Such a chance was denied to me. 这个机会跟我无缘。 5.All are not thieves that dogs bark at. 被狗叫的人不一定都是贼。（犬之所吠，并非皆贼） 6.He kept himself apart from the other children. 他和其他孩子保持距离，一个人待着。 7.No deposit will be refunded unless ticket produced. 如果不出示票据，押金是不会返还的。 8.他决不会说出这样的话. He should never have dreamt of saying such a thing. 9.她抱怨名单上没有她的名字． She complained about her name should be on the list. 10.他尽力克服技术资料的不足． He tried his best to overcome the lack of technical data. 11.在收据尚未签字以前不得付款. Don’t pay unless the receipt was signed. 12.他上火车站去接他的朋友，可是在人群中没见到他。（miss） He goes to the railway station to meet a friend, but he missed his friend in the crowd. 13.他直到三年级才认识到广泛阅读的重要性。（not…until） He did not realized the importance of the wider reading until three grade. 14.我警告过你，不要跟陌生人谈论我的事。（warn against） I have warned you against talking about me with strangers.
脐带血造血干细胞库管理办法（试行） 第一章总则 第一条为合理利用我国脐带血造血干细胞资源，促进脐带血造血干细胞移植高新技术的发展，确保脐带血 造血干细胞应用的安全性和有效性，特制定本管理办法。 第二条脐带血造血干细胞库是指以人体造血干细胞移植为目的，具有采集、处理、保存和提供造血干细胞 的能力，并具有相当研究实力的特殊血站。 任何单位和个人不得以营利为目的进行脐带血采供活动。 第三条本办法所指脐带血为与孕妇和新生儿血容量和血循环无关的，由新生儿脐带扎断后的远端所采集的 胎盘血。 第四条对脐带血造血干细胞库实行全国统一规划，统一布局，统一标准，统一规范和统一管理制度。 第二章设置审批 第五条国务院卫生行政部门根据我国人口分布、卫生资源、临床造血干细胞移植需要等实际情况，制订我 国脐带血造血干细胞库设置的总体布局和发展规划。 第六条脐带血造血干细胞库的设置必须经国务院卫生行政部门批准。 第七条国务院卫生行政部门成立由有关方面专家组成的脐带血造血干细胞库专家委员会（以下简称专家委
员会），负责对脐带血造血干细胞库设置的申请、验收和考评提出论证意见。专家委员会负责制订脐带血 造血干细胞库建设、操作、运行等技术标准。 第八条脐带血造血干细胞库设置的申请者除符合国家规划和布局要求，具备设置一般血站基本条件之外， 还需具备下列条件： （一）具有基本的血液学研究基础和造血干细胞研究能力； （二）具有符合储存不低于1 万份脐带血的高清洁度的空间和冷冻设备的设计规划； （三）具有血细胞生物学、HLA 配型、相关病原体检测、遗传学和冷冻生物学、专供脐带血处理等符合GMP、 GLP 标准的实验室、资料保存室； （四）具有流式细胞仪、程控冷冻仪、PCR 仪和细胞冷冻及相关检测及计算机网络管理等仪器设备； （五）具有独立开展实验血液学、免疫学、造血细胞培养、检测、HLA 配型、病原体检测、冷冻生物学、 管理、质量控制和监测、仪器操作、资料保管和共享等方面的技术、管理和服务人员； （六）具有安全可靠的脐带血来源保证； （七）具备多渠道筹集建设资金运转经费的能力。 第九条设置脐带血造血干细胞库应向所在地省级卫生行政部门提交设置可行性研究报告，内容包括：
译国译民 专心翻译 做到极致 常用十大翻译技巧之五：正反译法 正译法和反译法： 这两种方法通常用于汉译英，偶尔也用于英译汉。所谓正译，是指把句子按照与汉语相同的语序或表达方式译成英语。所谓反译则是指把句子按照与汉语相反的语序或表达方式译成英语。正译与反译常常具有同义的效果，但反译往往更符合英语的思维方式和表达习惯。因此比较地道。如： （1） 在美国，人人都能买到枪。 In the United States, everyone can buy a gun. (正译) In the United States, guns are available to everyone. (反译) （2） 你可以从因特网上获得这一信息。 You can obtain this information on the Internet. （正译） This information is accessible/available on the Internet. （反译） （3） 他突然想到了一个新主意。 Suddenly he had a new idea. (正译) He suddenly thought out a new idea. (正译) A new idea suddenly occurred to/struck him. （反译） （4） 他仍然没有弄懂我的意思。 He still could not understand me. (正译) Still he failed to understand me. (反译) （5） 无论如何，她算不上一位思维敏捷的学生。 She can hardly be rated as a bright student. (正译) She is anything but a bright student. (反译) （6） Please withholdthe document for the time being. 请暂时扣下这份文件。（正译） 请暂时不要发这份文件。（反译）
被动语态 现在范畴一般现在时am/is/are made 现在进行时am / is /are being made 现在完成时has/have been made 过去范畴一般过去时was/were made 过去进行时was/werebeingmade 过去完成时had been made 将来范畴一般将来时shall/will be made 将来完成时shall/will have been made 过去将来时should/would be made 过去将来完成时should/would have been made 1. 被动语态的各种时态 被动语态（The Passive Voice）是动词的一种形式，表示主语是谓语动词的承受者。被动 语态便于论述客观事实，故常用于科技文章、新闻报道、书刊介绍以及景物描写。被动语态没有将来进行时、过去将来进行时和完成进行时形式。 (1) 一般现在时的被动语态 I am not so easily deceived. 我不会轻易上当受骗的。 Computers are widely used in the world. 计算机在世界范围内得到广泛应用。 (2) 一般过去时的被动语态 The car was seriously damaged. 汽车受到严重损坏。 Printing was introduced into Europe from China. 印刷术是由中国传入欧洲的。 (3) 现在进行时的被动语态 The question is being discussed at the meeting. 这个问题现在正在会上讨论。 The children are being taken care of by their aunt. 孩子们现在正由其姑妈照看。 (4) 过去进行时的被动语态 When I called, tea was being served. 当我来访时，正值上茶之际。 When they arrived，the experiments were being made. 他们到达时，实验正在进行。
Review 1.The last person to be speaking about terrorism is the representative of country A. 最没有资格谈论恐怖主义问题的人就是A国的代表。 2.What, if any, effect do you feel the imports of Canadian gas will have on the American producer? 你觉得进口加拿大的天然气对美国生产者可能产生什么影响吗？ 3.他是一位中国现代优秀作家 He is an outstanding contemporary Chinese writer. [误译分析] 【原文】 The roofs loomed in front of them with starting clarity. 暗礁在他们面前令人吃惊地清楚，时隐时现。 【改译】暗礁在他们面前隐隐呈现，看得越清楚就越感到毛骨悚然 英语句子经常使用连词、关系代词、关系副词、短语中又包括介词短语、动名词短语、分词短语、不定式短语等，汉语如果照译，读者可能不知所云。按照汉语习惯，可将这些英语特有的结构转译为短句。例如： 1.The idea of a fish being able to generate electricity strong enough to light small bulbs, even to run an electric motor, is almost unbelievable. 鱼能发电，其强度足以点亮小灯泡，甚至能开动马达，这简直是令人难以置信 的。 2.Flooded with calls, the company is maximizing profits by handling in-city runs. 要车的人太多了，公司便只接来往于市区的生意，这样好多多赚钱。 【翻译技巧】转句译法 Conversion of words or phrases into sentences 有些词和各种短语所含的语义是相当的丰富，但是单靠换序、转性等方法还是 不能表达原文的真实含义，而要把原文的内容连词形式一起翻译成汉语几乎不 可能的，因此，不得不把这些词、词组转译成句子，称为转句译法。 1.Pressure of work has somewhat delayed my answer. 由于工作很忙，答复稍迟了一些。（主语转句） 2.Another hour’s ride will bring us to the village.
第三节写作中真正实用的英语语法 据考证，“语法”一词源于希腊语“Grammatike”，意指体现于写作过程中的“文字的技巧”，它是语言运用的规则，构建句子的框架，遣词造句的黏合剂，也是英语各项技能的基础，尤其在写作过程中起着举足轻重的作用。 但四、六级考试改革中对语法题目的减少使很多人误以为语法的地位被削弱，加之近年来重视综合技能的各类语言理论的出现，使得一部分考生在写作复习过程中完全摈弃对语法部分的准备，久而久之，形成了“轻语法，重语感”的习惯。而另一部分考生则缺乏必要的语法运用能力，他们可以准确解答语法题目，却不能在作文中灵活运用语法写出漂亮句子。这些考生文章的共同特点就是只有其意，不见其形。 语言是思维的外衣，准确的语法是高分作文的重要必备条件。如果考生能在写作中娴熟地运用语法技巧，就可以使文章逻辑严密，形神兼备。 鉴于语法体系庞大繁杂而备考时间有限，此节内容无法涵盖整个语法体系，只能选择写作中出现频率较高的语法进行重点讲解，如状语前置、倒装、虚拟语气、强调句等，并辅以例句讲解，希望能够帮助考生扫除写作中的语法障碍，轻松闯关。 状语前置 一般而言，英语句子中，状语成分的位置是可前可后的。但状语的前置是六级作文中常用的句式。所谓状语前置，就是把修饰动词的状语结构，如分词短语，介词短语，动词不定式结构等放到句首。 这一句式的最大优点就是断句自然，让单调的句子有跳跃的节奏感。请看下面句子： 1）With the expansion of industrialization, requirement for energy all over the world is on the rise.（随着工业化进程的发展，全世界的能源需求都在增加。） 2）Once lushly forested, this region has seen more than 80% of its original vegetation cut down or burned. (这个地区曾经丛林密布，但现在80% 的原生植被被砍伐或焚烧。) 3）To reach millions of people who watch television, advertisers are willing to pay big money. (为了能抓住千千万万的电视观众，广告商们不惜花费巨额资金。) 在以上例句中，状语的前置使得句子结构分明，避免了后置的平庸化，尤其是第二个句子中的状语部分，既简洁又有力，本身就是一个出彩的表达，如果放置到句尾就不会出现这种效果了。而第三句中不定式目的状语的前置还在一定程度上起到了强调的作用。 倒装 倒装又分为全部倒装和部分倒装。全部倒装是指将句子中的谓语动词全部置于主语之前。部分倒装是指将谓语的一部分如助动词或情态动词置于主语之前。如果句中的谓语没有助动词或情态动词，则需添加助动词do, does或did等,并将其置于主语之前。倒装的作用是为了强调或平衡句子结构。 倒装本身是较复杂的高级结构，如果在六级写作中能加以正确运用，就特别
1 【翻译技巧】英语笔译技法——正反译法 2 由于国家、历史、地理、社会文化背景和生活习性的不同，汉英两种语言在表达正3 说和反说时有很大差异，尤其英语在否定意义的表达上更为复杂，有时形式否定而实质4 肯定，或形式肯定而实质否定。在两种语言互译时，原文中正说的句子可能不得不处理5 成反说，或是用反说表达更为合适。反之亦然。翻译中，这种把正说处理成反说、把反6 说处理成正说的译法，就称为正反译法。 7 8 正反译法是翻译技巧中的一个重要方法，属于引申和修辞范围。 9 10 笼统的说，英语句子中含有“never”、“no”、“not”、“un-”、“im-”、11 “in-”、“ir-”、“-less”等否定词以及否定前缀或后缀的单词，以及汉语句子中12 含有“不”、“没”、“无”、“未”、“甭”、“别”、“休”、“莫”、“非”、13 “勿”、“毋”等否定词的即为反说，不含有这些否定词的即为正说。 14 15 但实际操作时，正说和反说的界限又变得极为模糊，例如“correct”可以翻译成16 “正确”（正说），也可以翻译成“没有毛病”（反说）。因此，到底译文要采用正说还17 是反说，就完全要看译文语言的惯用表达和上下文的语气语态了。 18 19 在正反译法中，英译汉正转反（正说反译法）和汉译英反转正（反说正译法）是最20 为重要的两种正反译法。 21
22 英译汉正转反 23 24 英语中有些否定概念是通过含有否定意义或近似否定意义的词来表达的，虽然形式25 是肯定的，但这类词大多是某些肯定词所引申或变化出来的反义词，或经过长期历史演26 变而引申出其他否定词义，即所谓的“含蓄否定词”或“暗指否定词”，这类词在译成27 汉语时，需要变成汉语的否定词组，必要时还需要作词类转换。 28 29 1、名词 30 —含蓄否定名词主要有：shortness / shortage（不够；不足）、lack（缺乏；没31 有）、absence（不在）、failure（未能；不成功）、defiance（不顾；无视）、denial 32 （否认；否定）、exclusion（排除）、freedom（不；免除）、refusal（不愿；不允33 许）、loss（失去）等。 34 Shortness of time has required the omission of some states. 由于时间不够，35 没能访问那些国家。 36 37 Behave yourself during my absence. 我不在时要规矩点。 38 39 We were perplexed by his failure to answer the letter. 他何以不回信，我40 们大惑不解。 41 2、动词或动词短语 42
最新《英语语法手册》电子版 在实用英语备受青睐的现在，大家在学习英语和准备各种考试时，总是把听说读写放在首位，诚然，学习语言重在实践。但是，请不要忽视语法的作用，特别是在阅读和写作中，他能帮助你分析清楚句子结构，准确抓住句子的要点，更能帮你写出复杂而优美的长句。 以下为你整理《英语语法手册》全集，不需背诵记忆，只要静下心阅读一遍，就能有所收获！ 宝宝更希望你能把他们融在平时的阅读写作里. [英语语法手册]关于词类和句子成分 根据词的形式、意义及其在句中的功用将词分为若干类，叫做词类。一个句子由各个功用不同的部分所构成，这些部分叫做句子成分。 学一个词，要学它的发音、拼法、意义，也要记它的词类；更重要的是要了解它和其他词的关系，及其在句中作什么句子成分。如China is in East Asia(中国位于东亚)一句中的China这个单词所属的词类是名词，在句子中作主语。 词类(parts of speech) 英语的词通常分为十大类： 1）名词(noun，缩写为n.)是人和事物的名称，如pen(钢笔)，
English(英语)，life(生活)。 2)代词(pronoun，缩写为pron.)是用来代替名词的词，如we(我们)，his(他的)，all(全部)。 3)形容词(adjective，缩写为adj.)用来修饰名词，如great(伟大的)，honest(诚实的)，difficult(困难的)。 4)数词(numeral，缩写为num.)是表示"多少"和"第几"的词，如four(四)，eighteen(十八)，first(第一)，eighth(十八)，hundred(一百)。 5)动词(verb，缩写为v)表示动作和状态，如write(写)，walk(行走)，think(想)。 6)副词(adverb，缩写为。adv.)是修饰动词、形容词和副词的词，如quickly(快)，often(经常)，very(很)。 7)冠词(article，缩写为art.)说明名词所指的人或物的词，如a，an(一个)，the(这，那)。 8)介词(preposition，缩写为prep.)表示名词(或代词)与句子里其它词的关系，如from(从)，in(在…内)，between(在…之间)。 9)连词(conjunction，缩写为conj.)是连接词、短语、从句和句子的词，如and(和)，because(因为)，if(假如)。 10)感叹词(interjection，缩写为int.)表示感情，如。oh(噢)，aha(啊哈)，hush(嘘)。 [注一]属于前六类(名、代、形、数、动、副等词)的词都有实义，
卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规 范(试行)》的通知 【法规类别】采供血机构和血液管理 【发文字号】卫办医政发[2009]189号 【失效依据】国家卫生计生委办公厅关于印发造血干细胞移植技术管理规范(2017年版)等15个“限制临床应用”医疗技术管理规范和质量控制指标的通知 【发布部门】卫生部(已撤销) 【发布日期】2009.11.13 【实施日期】2009.11.13 【时效性】失效 【效力级别】部门规范性文件 卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规范（试行）》的通知 （卫办医政发〔2009〕189号） 各省、自治区、直辖市卫生厅局，新疆生产建设兵团卫生局： 为贯彻落实《医疗技术临床应用管理办法》，做好脐带血造血干细胞治疗技术审核和临床应用管理，保障医疗质量和医疗安全，我部组织制定了《脐带血造血干细胞治疗技术管理规范（试行）》。现印发给你们，请遵照执行。 二〇〇九年十一月十三日
脐带血造血干细胞 治疗技术管理规范（试行） 为规范脐带血造血干细胞治疗技术的临床应用，保证医疗质量和医疗安全，制定本规范。本规范为技术审核机构对医疗机构申请临床应用脐带血造血干细胞治疗技术进行技术审核的依据，是医疗机构及其医师开展脐带血造血干细胞治疗技术的最低要求。 本治疗技术管理规范适用于脐带血造血干细胞移植技术。 一、医疗机构基本要求 （一）开展脐带血造血干细胞治疗技术的医疗机构应当与其功能、任务相适应，有合法脐带血造血干细胞来源。 （二）三级综合医院、血液病医院或儿童医院，具有卫生行政部门核准登记的血液内科或儿科专业诊疗科目。 1.三级综合医院血液内科开展成人脐带血造血干细胞治疗技术的，还应当具备以下条件： （1）近3年内独立开展脐带血造血干细胞和（或）同种异基因造血干细胞移植15例以上。 （2）有4张床位以上的百级层流病房，配备病人呼叫系统、心电监护仪、电动吸引器、供氧设施。 （3）开展儿童脐带血造血干细胞治疗技术的，还应至少有1名具有副主任医师以上专业技术职务任职资格的儿科医师。 2.三级综合医院儿科开展儿童脐带血造血干细胞治疗技术的，还应当具备以下条件：
隶书 起源及特点 隶书也叫“隶字”、“古书”。是在篆书基础上，为适应书写便捷的需要产生的字体。就小篆加以简化，又把小篆匀圆的线条变成平直方正的笔画，便于书写。分“秦隶”(也叫“古隶”)和“汉隶”(也叫“今隶”)，隶书的出现，是古代文字与书法的一大变革。 隶书是汉字中常见的一种庄重的字体，书写效果略微宽扁，横画长而直画短，讲究“蚕头燕尾”、“一波三折”。它起源于秦朝，在东汉时期达到顶峰，书法界有“汉隶唐楷”之称。也有说法称隶书起源于战国时期。 隶书是相对于篆书而言的，隶书之名源于东汉。隶书的出现是中国文字的又一次大改革，使中国的书法艺术进入了一个新的境界，是汉字演变史上的一个转折点，奠定了楷书的基础。隶书结体扁平、工整、精巧。到东汉时，撇、捺等点画美化为向上挑起，轻重顿挫富有变化，具有书法艺术美。风格也趋多样化，极具艺术欣赏的价值。 书写方法 隶变后的字，与篆书相比，就是具备了鲜明的点画持征。笔法有方有圆，方圆并用。下面，以明朗的笔迹演示，结合相对切实的例字，给大家详尽讲解隶书的基本写法。掌握这些基本写法后，隶书的基础成就了一大步。 一、横画 横画是隶书中有特色的笔画。往往以“横飞”为美。隶书的横画有两种，一为平横，一为波横。有方笔圆笔两种。 1.平横。是指横呈水平状，一般逆锋起笔，折笔中锋运行，回锋收笔或露锋收笔。平横有凸形、凹形和基本平形。
2.波横。是波笔的一种，是指横画具有俯仰之态。一般逆锋起笔，折笔重顿，形成蚕头，然后提笔运行，至收笔处顿挫出锋，形成燕尾。亦有蚕头小燕尾大的现象。波横一般要写得厚重圆润，蚕头、燕尾都要饱满，横中略向上弯。 二、竖画 竖画在隶书中只是普通的一个笔画，这个笔画承篆成分较大，即多数为圆起圆收。有些竖末端较尖，亦不属楷书悬针竖，而是写时自然收结。隶书的竖一般均为逆锋起笔，中锋徐行，藏锋收笔。竖画在隶书中有三种形式：中竖，向左弧竖，向右弧竖。也有方笔，即逆锋起笔，向左上角切，折笔下行。虽然竖画在隶书中不如波画有特色，但书写时同样不可轻视。 1.以坚代撇
实用英语语法大全-anyone还是whoever anyone还是whoever 请看下面的题目： _________ with any common sense can tell the difference between the two. A. Who B. Whoever C. Anyone D. Who ever 【陷阱】容易误选B。 【分析】答案为C。有的同学误选B主要是因为受以下这类句子 的影响： Whoever comes will be welcome. 任何人来都欢迎。 Whoever wants the book may have it. 任何人要这书都可拿去。 Whoever gets the job will have a lot of work. 谁要是得到 这份工作就有很多事要做。 以上三句中 whoever 引导的均为主语从句，其中的 whoever均 可换成 anyone who，但是不能换成 anyone。以上试题从表面上看， 与以上各例很相似，其实它们有本质的不同，即 _____ with any common sense 中没有谓语动词，所以我们不能选 whoever。此题的准 确答案为C，anyone 为句子主语，with any common sense 为修饰anyone 的定语。现将此题稍作改动如下，答案选B： _______ has any common sense can tell the difference between the two. A. Who B. Whoever
C. Anyone D. Who ever
卫生部关于印发《脐带血造血干细胞库设置管理规范(试行)》的通知 发文机关：卫生部(已撤销) 发布日期： 2001.01.09 生效日期： 2001.02.01 时效性：现行有效 文号：卫医发(2001)10号 各省、自治区、直辖市卫生厅局： 为贯彻实施《脐带血造血干细胞库管理办法（试行）》，保证脐带血临床使用的安全、有效，我部制定了《脐带血造血干细胞库设计管理规范（试行）》。现印发给你们，请遵照执行。 附件：《脐带血造血干细胞库设置管理规范（试行）》 二○○一年一月九日 附件： 脐带血造血干细胞库设置管理规范（试行） 脐带血造血干细胞库的设置管理必须符合本规范的规定。 一、机构设置 （一）脐带血造血干细胞库（以下简称脐带血库）实行主任负责制。 （二）部门设置 脐带血库设置业务科室至少应涵盖以下功能：脐带血采运、处理、细胞培养、组织配型、微生物、深低温冻存及融化、脐带血档案资料及独立的质量管理部分。 二、人员要求
（一）脐带血库主任应具有医学高级职称。脐带血库可设副主任，应具有临床医学或生物学中、高级职称。 （二）各部门负责人员要求 1．负责脐带血采运的人员应具有医学中专以上学历，2年以上医护工作经验，经专业培训并考核合格者。 2．负责细胞培养、组织配型、微生物、深低温冻存及融化、质量保证的人员应具有医学或相关学科本科以上学历，4年以上专业工作经历，并具有丰富的相关专业技术经验和较高的业务指导水平。 3．负责档案资料的人员应具相关专业中专以上学历，具有计算机基础知识和一定的医学知识，熟悉脐带血库的生产全过程。 4．负责其它业务工作的人员应具有相关专业大学以上学历，熟悉相关业务，具有2年以上相关专业工作经验。 （三）各部门工作人员任职条件 1．脐带血采集人员为经过严格专业培训的护士或助产士职称以上卫生专业技术人员并经考核合格者。 2．脐带血处理技术人员为医学、生物学专业大专以上学历，经培训并考核合格者。 3．脐带血冻存技术人员为大专以上学历、经培训并考核合格者。 4．脐带血库实验室技术人员为相关专业大专以上学历，经培训并考核合格者。 三、建筑和设施 （一）脐带血库建筑选址应保证周围无污染源。 （二）脐带血库建筑设施应符合国家有关规定，总体结构与装修要符合抗震、消防、安全、合理、坚固的要求。 （三）脐带血库要布局合理，建筑面积应达到至少能够储存一万份脐带血的空间；并具有脐带血处理洁净室、深低温冻存室、组织配型室、细菌检测室、病毒检测室、造血干/祖细胞检测室、流式细胞仪室、档案资料室、收/发血室、消毒室等专业房。 （四）业务工作区域应与行政区域分开。
超实用英语语法顺口溜 用顺口溜来学习英语，至少有三大好处：一是节省了时间。死记硬背效果差不说，还费时间，而利用顺口溜，效率又高又省时；二是培养了自己的概括思维能力。把一些词语编成顺口溜，看似容易，其实也难；三是使人觉得学习英语还是饶有兴趣的。 既然顺口溜有这么多好处，那么，何乐而不为呢 动词为纲滚雪球难易编组抓循环同类归纳印象深图示介词最直观 混淆多因形音义反义词语成对念构词方法不可忘习惯用语集中练 词不离句法最好课外阅读莫间断 be的用法口诀 我用am你用are，is连着他，她，它；单数名词用is，复数名词全用are. 变疑问，往前提，句末问号莫丢弃变否定，更容易，be后not莫忘记 疑问否定任你变，句首大写莫迟疑 时间名词前所用介词的速记歌 年月周前要用in，日子前面却不行遇到几号要用on，上午下午又是in. 要说某日上下午，用on换in才能行午夜黄昏须用at，黎明用它也不错 at也用在明分前，说差可要用上to，说过只可使用past，多说多练牢牢记，莫让岁月空蹉跎可数名词的复数变化规律[1]: 名词复数有规律，一般词尾加s;辅音字母+y型，变y为i,es; s,x ch,sh 真有趣+ es; f,fe真小气，字母v来把它替，es在后别忘记；字母o来真神奇，有生命来es,没有生命+s. 可数名词复数特殊变化规律[2]: 中日好友来聚会，绵羊、鹿、鱼把家回。男士、女士a变e man--men woman--women； 鹅，脚，牙（齿）双o 变双e; goose--geese foot--feet tooth--teeth 孩子们想去天安门，原形后面r、e、n; child--children 老鼠本来爱大米，mice,ice 和rice. mouse--mice 注：中Chinese,日Japanese，好友people. 绵羊sheep,鹿deer,鱼fish （这些单词单复数一样） 一般现在时态 I、we you、they 作主语， 动词原形后面跟；否定句，更容易，动词前面加don't; 疑问句，别着急，句首Do,来帮你，后面问号别忘记；肯定回答用Yes, I、we you、they加上do;