The epistemology of hedged laws

Standard objections to the notion of a hedged, or ceteris paribus, law of nature usually boil down to the claim that such laws would be either (1) irredeemably vague, (2) untestable, (3) vacuous, (4) false, or a combination thereof. Using epidemiological studies in nutrition science as an example, I show that this is not true of the hedged law-like generalizations derived from data models used to interpret large and varied sets of empirical observations. Although it may be ‘in principle impossible’ to construct models that explicitly identify all potential causal interferers with the relevant generalization, the view that our failure to do so is fatal to the very notion of a cp-law is plausible only if one illicitly infers metaphysical impossibility from epistemic impossibility. I close with the suggestion that a model-theoretic approach to cp-laws poses a problem for recent attempts to formulate a Mill–Ramsey–Lewis theory of cp-laws.     

水溶液中硼酸的酸式离解及其强化问题

对硼酸在水溶液中的酸式离解及其强化问题进行了研究 ,结果表明 :硼酸是一元路易斯酸 ,甘露醇、甘油等邻多羟基化合物能与其形成配合物使其酸性大大增强。     

论芒福德的技术哲学

芒福德是一位世界著名的技术哲学家，是人文主义技术哲学的重要代表人物之一。他首先从技术人类学角度将技术史分为使用水和木材的始技术、煤和铁的古技术以及电和合金的新技术三个阶段，然后将历史上的技术分为两类：多元技术和单一技术。他认为人与技术协调发展的多元技术逐渐被以“巨型机器”为代表的单一技术所取代，产生了“机器的神话”，人被沦为机器的奴隶。芒福德提倡一种“民主的技术”，以改变单一技术的文明，从而恢复人在技术发展中的主体地位，实现人和技术的协调发展。     

《瑞普·凡·温克尔》与《桃花源记并诗》理想追求之比较

从作品主题,表现方法和社会理想三个方向对《瑞普·凡·温克尔》与《桃花源记并诗》中的理想追求进行了比较分析.由于两位作者所处的时代背景、文化传统和思想倾向的差异,在作品中其各自的表达方式和理想追求也不尽相同.     

The Diels-Alder reaction and biopolymer catalysis

The Diels-Alder reaction provides a general and facile entry for the synthesis of six-membered cyclic structures. Consequently, it has been used extensively by organic chemists for the construction of complex compounds with pharmaceutical potential. Nature also appears to have utilized this reaction in the biosynthesis of several secondary metabolites. Given its utility, various catalysts have been discovered for the reaction ranging from simple Lewis acidic transition metals to complex catalytic antibodies. More recently, modified RNA has also been shown to be an effective Diels-Alderase with a highly specific active site. The RNA Diels-Alderase activity was also shown to be absolutely dependent on the nature of the base modification and the presence of cupric ion. Together, these results suggest that this RNA Diels-Alderase achieves a portion of its rate acceleration through Lewis acid catalysis, a different mechanistic mode than similar protein Diels-Alderases. The notion that RNA can accelerate reactions through Lewis acid catalysis suggests that modified RNA may serve as a tunable catalytic platform for the creation of structurally diverse compounds using a variety of powerful chemical transformations. Received 28 December 1998; received after revision 25 February 1999; accepted 26 February 1999     

路易斯酸催化合成香料醋酸苯甲酯

研究以路易斯酸氯化锌为催化剂,乙酸和苄醇为原料合成醋酸苯甲酯的工艺条件。结果表明,反应的最佳条件是:冰醋酸¨苯甲醇=1.0¨2.0,带水剂10ml,催化剂1.5g,回流反应时间2.5h。在此条件下,酯收率达到93.2%。     

α-1,3-Fucosyltransferase-VII stimulates the growth of hepatocarcinoma cells via the cyclin-dependent kinase inhibitor p27Kip1

After the transfection of -1,3-fucosyltransferase (FucT)-VII cDNA into H7721 human hepatocarcinoma cells, the protein expression of some cyclins, cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CDIs) p16^INK4 and p21^waf1/Cip1 were unchanged. However, CDI p27^Kip1 protein, both the total amount and the amount that bound to CDK2, but not its mRNA, was significantly reduced. The de-inhibited CDK2 stimulated the phosphorylation of retinoblastoma (Rb) protein and facilitated the G1/S transition and growth rate of the cells. The decrease of p27^Kip1 protein, the increase of CDK2 activity and Rb phosphorylation, as well as the cell growth and percentage of S phase cells were correlated to the increased amount of cell surface sialyl Lewis X (SLe^x) antigen in cells with different -1,3-FucT-VII expression. The reduction in p27^Kip1 and the difference in its expression among different transfected cells were blocked by the SLe^x antibody KM93 in a dose-dependent manner, indicating that p27^Kip1 expression was influenced by -1,3-FucT-VII and its product SLe^x. The MEK/MAPK signaling pathway was more important than the PI-3K pathway in the regulation of p27^Kip1 expression.Received 5 August 2004; received after revision 25 October 2004; accepted 11 November 2005     

从"高上意志及卑下意志之对峙"到"以理制欲"--试论白璧德"新人文主义"在当前中国的一例误读

“新人文主义”在中国的影响与接受主要分为两个时期：1920—30年代的“学衡时期”;始于20世纪90年代的“新时期”。其间我国对“新人文主义”的研究缺少传承,甚至直接显示为断代。最显著的表现就是,关于“高上意志”对“卑下意志”的“内在制约”这一“新人文主义”核心思想,部分新时期研究者未加分辨地接受了学衡时期阐释者们给出的解读,致使这一核心概念在新时期的再阐释过程中发生了明显的变形。因此,我们要尽可能充分地理解前人所处的时代背号与当时学人的独特心态,这样或可避免谬误流传。     

中国劳动力市场结构转型的拐点、特征与对策研究

从农业、劳动密集型行业及收入分配差距等角度建立了计量经济模型,验证了中国劳动力市场已在2006年前后出现了结构转型的拐点,即中国越过刘易斯第一转折点(即劳动力短缺点),进入劳动力有限供给阶段。并指出,我国劳动力市场进入结构变迁阶段面临的负面影响是存在高通胀低增长的风险,但面临的正面影响更多;越过刘易斯第一转折点后,由于经济内生增长的激励,消费带动内需扩大的经济增长将有效地带动产业升级和经济增长的持续,同时收入分配差距将会缩小。     

对“由‘刘易斯拐点’引发‘比较优势’的忧思”的反忧思

“刘易斯拐点”是否逼近中国这不仅是一个理论问题,更是一个重大的实践问题。如果对于这个问题在认识上发生偏差,我们将会在实践中带来难以预估的困境和损失,正是基于这个原因,我们必须对“由‘刘易斯拐点’引发‘比较优势’的忧恩”的观点作反向思考．