Taming theory with thought experiments: Understanding and scientific progress

I claim that one way thought experiments contribute to scientific progress is by increasing scientific understanding. Understanding does not have a currently accepted characterization in the philosophical literature, but I argue that we already have ways to test for it. For instance, current pedagogical practice often requires that students demonstrate being in either or both of the following two states: 1) Having grasped the meaning of some relevant theory, concept, law or model, 2) Being able to apply that theory, concept, law or model fruitfully to new instances. Three thought experiments are presented which have been important historically in helping us pass these tests, and two others that cause us to fail. Then I use this operationalization of understanding to clarify the relationships between scientific thought experiments, the understanding they produce, and the progress they enable. I conclude that while no specific instance of understanding (thus conceived) is necessary for scientific progress, understanding in general is.     

Nodal signals pattern vertebrate embryos

Vertebrate embryonic patterning requires several conserved inductive signals–including Nodal, Bmp, Wnt and Fgf signals. Nodal, which is a member of the transforming growth factor β (TGFβ) superfamily, activates a signal transduction pathway that is similar to that of other TGFβ members. Nodal genes, which have been identified in numerous vertebrate species, are expressed in specific cell types and tissues during embryonic development. Nodal signal transduction has been shown to play a pivotal role in inducing and patterning mesoderm and endoderm, and in regulating neurogenesis and left-right axis asymmetry. Antagonists, which act at different steps in the Nodal signal transduction pathway, have been shown to tightly modulate the inductive activity of Nodal. Received 20 October 2005; received after revision 15 November 2005; accepted 25 November 2005     

二滩水电站的兴建对陆生脊椎动物的影响及对策

分析了二滩水电站在施工期，竣工蓄水后，水库水位消涨对陆生脊椎动物的影响及应采取的对策。     

几种脊椎动物红细胞血型的比较研究

采用两种方法对脊椎动物各纲的代表动物小白鼠、家兔、家鸽、蟾蜍、鲫鱼的红细胞血型进行了研究 .方法一 :采用人类抗A、抗B标准血清与上述动物的红细胞进行反应 ,结果均未出现凝集现象 ,表明 :这几种动物的红细胞膜上 ,没有与人类抗A、抗B标准血清起反应的A凝集原和B凝集原 .方法二 :采用同种动物的血清与同种动物不同个体的红细胞进行反应 ,结果 :上述几种动物的红细胞与同种内不同个体的血清均不发生凝集反应 .     

宁夏药用脊椎动物资源的现状、利用与保护

根据11a的野外调查，发现宁夏有药用脊椎动物91种，其中25种具有重要开发利用价值。生态区划可分为一级与二级生态区。提出了开发代用品等利用途径和制订科学的猎取量等保护策略，以推动宁夏的药用动物研究和动物产品的开发利用。     

肺微血管研究进展

综述了脊椎动物肺微血管构筑的研究进展及特点．两栖动物在囊状肺的内表面出现了网状隔膜与次级隔膜，以增加气体交换面积，提高气体交换率；爬行动物肺内壁上不仅有网状隔膜和次级隔膜，还出现了三级隔膜，使得动物肺壁内表面积有较大增加，显示其结构比两栖动物有较大进步，更有利于进行气体交换；鸟肺三级支气管与周围放射状紧密排列的微气管结构上排列着丰富的毛细血管网，并相互吻合成密集的立体微血管网，呼吸表面积大为增加，比两栖、爬行动物又有更大进步；哺乳动物和人肺则由发达的支气管系统及大量的肺泡囊与肺泡构成，肺泡与肺泡隔毛细血管为密集网，显示肺结构有极大的呼吸表面积，更有利于血液与进入肺内的空气进行气体交换．肺脏微血管的三维构筑特点及变化充分显示了动物与生存环境相适应的结构特点，亦体现出生物由低等向高等进化过程中结构与功能相适应的规律．     

新源山地草甸类草地自然保护区脊椎动物调查报告

1994年6月27日至7月9日对新源县境内新源山地草甸类草地自然保护区进行了动物资源调查,发现脊椎动物64种,其中鱼类5种,两栖动物2种,爬行动物1种,鸟类39种,兽类17种。家鸦(Corvus splendens)是新疆新纪录,鼹形田鼠准噶尔示亚种(Ellobius talpinusursulus)系新疆首次采到。     

Pregnanes from defensive glands of a belostomatid bug

The aquatic bugAbedus herberti (Hemiptera: Belostomatidae) secretes a mixture containing four pregnanes (desoxycorticosterone (I), pregnenolone (II), progesterone (III), and 3-hydroxy-pregn-5-en-20-one (IV)) from its cephalic glands. Pregnanes had previously been characterized from the defensive glands of aquatic beetles (Dytiscidae) and shown to be deterrent to fish. It may be specifically under predation pressure from fish thatA. herberti and Dytiscidae evolved their comparable defenses.     

脊椎动物肋骨矢跨比的研究

着重分析了结构的最优矢跨比问题，分析了矢跨比对脊椎动物肋骨和钢结构临界载荷的影响．利用拱的屈曲理论，着重分析了脊椎动物肋骨的矢跨比，探讨了脊椎动物肋骨不是空间直线段而是空间拱形(矢跨比为0．25，在0．2和0．3之间)的力学机理．     

兴隆山自然保护区脊椎动物区系的研究

兴隆山自然保护区的脊椎动物调查是从1990年8月～1992年1月进行的,总共记录了154种和亚种,隶属于23目49科。 从我们获得的陆生脊椎动物的材料初步分析,有93种和亚种属于古北界,占61.18％,有9种属于东洋界的种类,占5.9％,其余50种和亚种,占32.89％为广布种,显然古北界的种类占优势。