大气污染对杉木生长影响的初步研究

对资江氮肥厂附近大乘山杉木生长情况所作的研究工作包括大气监测、杉叶叶绿素、钾离子外渗率、电解质外渗率及其营养元素N、P、K、Ca、Mg、全S含量的测定,树干解析,结果表明:离厂越近,大气污染物SO_2、NO_2、和NH_3等的浓度越高,杉叶叶绿素及其P、K、Ca、Mg等营养元素含量:对照区>污染区;而杉叶钾离子外渗率和电解质外渗率及其全S、全N含量为:污染区>对照区,且叶中全S和全N含员随着时间的推移逐渐增加,分析表明:大气污染是大乘山杉木衰亡的重要原因。     

肿瘤干细胞与乳腺癌发生发展的关系

目的了解肿瘤干细胞与乳腺癌发生发展关系的研究现状。方法复习国内外相关文献,综述肿瘤干细胞的特征、肿瘤干细胞与乳腺癌组织发生的相互关系及可能存在的信号分子机制和内分泌调控特征。结果肿瘤干细胞与乳腺癌的发生、发展、转移及耐药之间存在很强的相关性。结论肿瘤干细胞理论可解释乳腺癌的很多生物学行为,为临床诊断、治疗开辟了新的途径,但仍有许多问题尚待解决,有很长的路要走。     

刀额新对虾脑部胶质细胞和神经鞘

本文用透射电镜观察了刀额新对虾（Ｍｅｔａｐｅｎａｅｕｓ　ｅｎｓｉｓ）脑部神经胶质细胞和神经纤维髓鞘；结果表明。这些胶质细胞呈圆形或椭圆形，直径约６４００ｎｍ。在胞质中，没有观察到有线粒体，高尔基体等细胞结构，细胞核大电子致密的异染色质位于核边缘且连成块状，髓鞘直径约６４００—９３００ｎｍ。鞘层厚约５００—６７０ｎｍ。在髓鞘层中存在着微管结构，微管直径约８３ｎｍ。     

神经网络计算与生物神经活动

讨论了生物神经网络活动对神经网络计算的启发:神经元在大脑皮层上的拓朴结构,启发了多层神经网络计算;神经元的显微结构以及神经元的活动方式,启发了神经网络计算中权值矩阵的运用;神经活动的联想假说,启发了神经网络中的联想计算。     

城市“孙代照顾”与临时主干家庭生活:石家庄个案

随着更多的女性外出就业,核心家庭无暇完成孩子的抚育与照顾功能。基于传统伦理,老人来到子代的家庭组成"临时主干家庭",完成照顾孙代责任。在对石家庄市"临时主干家庭"个案调查的基础上,分析这一家庭形态的代际关系及家庭生活实践。临时主干家庭作为家庭功能实现的现实策略在于,一方面勾勒出当代中国家庭动态的家庭结构形式;另一方面,从临时主干家庭的互动实践中,可以看出老人在双方互动中权威地位的衰落,处于家庭中的附属地位。     

干细胞特性及最新研究进展

干细胞是人体的种子细胞,是构成人体各种组织细胞的最初来源,在一定条件下,它能分化演变成多种可利用的功能细胞.干细胞是一种具有自我更新,高度繁殖和多向分化潜能的细胞群体.近年来干细胞研究已经渗透到现代生命科学及医学的多个方向,该技术也实现了由实验室向临床应用的转化.干细胞疗法逐渐成为治疗多种疾病的新途径,具有重要的理论研究意义和临床应用价值.本文阐述了干细胞的特性及其在临床上的发展及应用.     

The Inverse Relation Between Risks and Benefits: The Role of Affect and Expertise

Although risk and benefits of risky activities are positively correlated in the real world, empirical results indicate that people perceive them as negatively correlated. The common explanation is that confounding benefits and losses stems from affect. In this article, we address the issue that has not been clearly established in studies on the affect heuristic: to what extent boundary conditions, such as judgments’ generality and expertise, influence the presence of the inverse relation in judgments of hazards. These conditions were examined in four studies in which respondents evaluated general or specific benefits and risks of “affect‐rich” and “affect‐poor” hazards (ranging from investments to applications of stem cell research). In line with previous research, affect is defined as good or bad feelings integral to a stimulus. In contrast to previous research, affect is considered as related both to personal feelings and to social controversies associated with a hazard. Expertise is related to personal knowledge (laypersons vs. experts) as well as to objective knowledge (targets well vs. poorly known to science). The direct comparison of the input from personal and objective ignorance into the inverse relation has not been investigated previously. It was found that affect invoked by a hazard guides general but not specific judgments of its benefits and risks. Technical expertise helps to avoid simplified evaluations of consequences as long as they are well known to science. For new, poorly understood hazards (e.g., stem cell research), expertise does not protect from the perception of the inverse relation between benefits and risks.     

解读美国人类胚胎干细胞研究现行法律与政策

2009年3月9日,美国总统奥巴马在白宫签署行政命令,宣布将解禁联邦基金对胚胎干细胞研究的资助限制。美国的胚胎干细胞研究走过了克林顿、布什两届政府,正式进入了奥巴马时代。通过对美国胚胎干细胞研究法律与政策的历史回顾,解读了现行法律与政策及对该项研究的影响。笔者认为,奥巴马秉持的＂政治不干预科学＂的政治立场对人类胚胎干细胞研究有良好的促进作用,但由于Dicky修正案及专利体系的影响,目前该项研究的前景依然不明朗。     

Approximate confidence bounds for ratios of variance components in two-way unbalanced crossed models with interactions

Consider the general unbalanced two-factor crossed components-of-variance model with interaction given by Y_ijk: = μ+A_i: +B_j: + C_ij: +E_ijk: (i = 1,2, … a; j = 1,…,b; k = 1,…,.n_ij:=0) A_i:,B_j:, C_ij: and E_ijk: are independent unobservable random variables. Also A_i:sim; N(0,σ² _A),B_j: ～ N(0,σ² _B), C_ij:～N(0,s² _C:) and E_ijk:～N(0,s² _E:). In this paper approximate confidence bounds are obtained for ρ_A: = ρ² _A/² and ρ_B: = ρ² _B:/ρ² (where σ² = σ² _A:+ σ² _B+σ² _Cσ² _E) for special cases of the above model. The balanced incomplete block model is studied as a special case.     

阅读理解测试的数据分析和比较

从文本、题干和选项三个方面对四、六级同GRE、TOEFL进行了数据分析和比较,以探求阅读理解测试在国内外发展趋势和构造设计方面的异同点。对句长与难度、题干类型及选项长度等方面的问题进行了探讨,提出了自己的见解,以促进阅读理解试题设计的完善与发展。