近代中国人造丝及其制品的进出口贸易

本文首先简述了人造丝进口贸易情况,分析了人造丝的进口国别和到达港口的变化。然后分别论述了人造丝织品和人造丝交织品的进、出口贸易的发展,分析了进出口额变化的原因。文中给出了人造丝及其制品进出口的一些资料。     

一类混沌二相编码脉冲压缩的性能分析

研究了一类混沌信号的二相编码问题。混沌信号对初值非常敏感,能产生大量的二相混沌码,从中可筛选出压缩性能比较好的二相码。在Matlab上的仿真表明,这种二相码具有较高的主副瓣比且数量较多,显示了较好的应用前景。还对该类二相码序列的长度N的大小取值、不同码长的二相码的最大主副瓣比值进行了探讨。分析了长度N、混沌序列初值以及二相码的位数对脉压性能的影响,并给出了最佳结果,可供工程应用参考。因篇幅所限,没有对该类二相码的多普勒性能及脉冲压缩的实现方法作进一步讨论。     

相位差变化率的测量方法及其测量精度分析

相位差变化率是最近提出的用于快速无源定位的观测量。分析了相位差变化率的特点,提出了相位差变化率的测量原理,从理论上分析了相位差变化率测量精度的Cramer-Rao界,指出了过窄的源信号脉冲宽度和过低的相位差变化率是造成相位差变化率测量困难的主要原因,并对此提出了解决的方法,随后进行的测量精度对比仿真分析表明,该方法是有效的。     

人力资源价值计量研究的突破与创新

人力资源价值计量本身具有特殊性、复杂性和不确定性，国内外研究了几十年，一直未能解决，使得企业对人力资源价值核算、绩效考核、收益分配因缺乏科学依据而很难做到公平合理。我们找到难题未能解决的症结所在，寻求了新的思路，提出了当期价值理论，构建了一系列计量模式，并经多家企业应用验证，取得了突破与创新，其主要内容：(1)从时间、空间、价值等涵义论证了当期价值理论的内涵；(2)运用科学方法，计算出人力资源对企业产出的贡献，将人力资源价值从物力资源中分离出来；(3)按投入产出的指导思想，构建了人力资源价值计量的基本模式，即以人力资源当期投入价值和人力资源当期创造的新价值之和作为人力资源当期实现群体价值；(4)运用价值指标与非价值指标的有机结合，实现当期群体、个体、绩效、分配以及未来群体、个体的六位价值的一体化；(5)建立人力资源价值核算体系，填补传统核算对人力资源价值反映的空白。     

13C NMR-study of flexibilide,an anti-inflammatory agent from a soft cora

Summary The use of¹³C spin-lattice relaxation measurements as a probe of structure in solution is illustrated for flexibilide. Analysis of quaternary carbon relaxation behaviour indicates that the structure in solution differs from the crystal structure. The effects of lanthanide shift and relaxation reagents on¹³C spectral parameters are also reported.Acknowledgment. We thank R.J. Wells, RRIMP, for helpful discussions.     

昆明鼠胚胎干细胞的分离培养与鉴定

目的：从昆明系小鼠的早期胚胎分离和培养胚胎干细胞(ES细胞)．方法：收集小鼠3．5d胚龄的囊胚，将其培养在小鼠胚胎成纤维细胞饲养层上，5—6d后取隆起生长的内细胞团块分离后再培养，观察集落的生长情况并通过碱性磷酸酶染色、原位杂交、细胞核型分析等对细胞集落进行鉴定．结果：KS细胞集落性生长，符合小鼠胚胎干细胞的一系列特性．结论：昆明系小鼠囊胚在胚胎成纤维细胞饲养层上可以发育成ES细胞，并能进行传代培养．     

Introduction: lipids as regulators of cell function

It is becoming increasingly clear that lipids are key regulators of cellular function and that these effects are quite diverse. First, the lipid environment in the cellular membrane bilayer is important in maintaining the normal function of receptors, enzymes, transporters and so on that are localized in the membrane. Phosphoinositides are important regulators of signalling molecules. Lipid metabolites formed by a number of enzymes including the cyclooxygenases, lipoxygenases and P450s also mediate important cellular functions. Fatty acids and lipid metabolites can also activate the nuclear peroxisome proliferator-activated receptors. Finally, a wide variety of lipid molecules are generated nonenzymatically by free-radical mechanisms that also exert potent biological effects in a wide variety of organs. Presented are a series of eight reviews that broadly cover all of these topics in some detail.     

Intermediate-depth earthquake faulting by dehydration embrittlement with negative volume change

Earthquakes are observed to occur in subduction zones to depths of approximately 680 km, even though unassisted brittle failure is inhibited at depths greater than about 50 km, owing to the high pressures and temperatures. It is thought that such earthquakes (particularly those at intermediate depths of 50-300 km) may instead be triggered by embrittlement accompanying dehydration of hydrous minerals, principally serpentine. A problem with failure by serpentine dehydration is that the volume change accompanying dehydration becomes negative at pressures of 2-4 GPa (60-120 km depth), above which brittle fracture mechanics predicts that the instability should be quenched. Here we show that dehydration of antigorite serpentinite under stress results in faults delineated by ultrafine-grained solid reaction products formed during dehydration. This phenomenon was observed under all conditions tested (pressures of 1-6 GPa; temperatures of 650-820 degrees C), independent of the sign of the volume change of reaction. Although this result contradicts expectations from fracture mechanics, it can be explained by separation of fluid from solid residue before and during faulting, a hypothesis supported by our observations. These observations confirm that dehydration embrittlement is a viable mechanism for nucleating earthquakes independent of depth, as long as there are hydrous minerals breaking down under a differential stress.