浅谈功率因数的补偿及其应用

根据我国当前电力系统运行情况，对电网无功功率补偿的必要性及通用补偿方法及其装置进行了具体阐述。     

西文期刊回溯建库中几个重要项目的著录

在实践的基础上，从期刊的出版日期、出版周期、卷、期、年、月及其他标识、ISSN、增刊、出版者以及期刊的历史发展等方面对西文期刊机读目录的标准化著录问题进行了探讨。     

顶凌覆盖节水增产技术研究

通过1998年、2000年的试验研究，系统分析了顶凌覆盖技术在高寒区节水增温保温、增产增收的机理及其应用效果。提出该技术可以缓解低温干旱特别是春旱对农业生产的困扰，是一项可以抗旱保春播增产增收的实用技术，在高寒地区具有较高的推广价值。     

完善农村税费改革的若干思考

农村税费改革方案实施一年来已取得初步成效 ,但在方案的执行过程中存在着计税依据不科学 ,乡村财力减少、运转困难等问题。建议采取科学设定计税依据 ,降低税率 ,开征土地使用税 ,取消农业特产税 ,取消农业税附加 ,开征农村建设税等措施完善方案 ,并进行相应配套改革     

Probing met repressor-operator recognition in solution.

The three-dimensional crystal structure of the Escherichia coli methionine repressor, MetJ, complexed with a DNA operator fragment is described in an accompanying article. The complex exhibits several novel features of DNA-protein interaction. DNA sequence recognition is achieved largely by hydrogen-bond contacts between the bases and amino-acid side chains located on a beta-ribbon, a mode of recognition previously hypothesized on the basis of modelling of idealized beta-strands and DNA, and mutagenesis of the Salmonella phage P22 repressors Arc and Mnt. The complex comprises a pair of MetJ repressor dimers which bind to adjacent met-box sites on the DNA, and contact each other by means of a pair of antiparallel alpha-helices. Here we assess the importance of these contacts, and also of contacts that would be made between the C-helices of the protein and DNA in a previous model of the complex, by studying mutations aimed at disrupting them. The role of the carboxy-terminal helix face in operator binding was unclear, but we demonstrate that recognition of operator sequences occurs through side chains in the beta-strand motif and that dimer-dimer interactions are required for effective repression.     

剑桥空间百科全书——任务、应用和探测

自从1957年苏联第一颗人造卫星发射成功后，至今已有30多个国家发射了8000多颗人造卫星和火箭，花费了数亿美元。难以置信的是有超过350人曾遨游在大气层之上，并在数不胜数的空间应用中获益匪浅。     

Heterostructure in ZnO Nano-Tetrapods

1 Introduction 　　Nanoscale science and technology have attracted greatattention since the novel properties become dominant for well-known materials as their sizes reduced to some critical dimension. These properties frequently originate in lattice distortions, structure transformations etc[1]. The variations of size and structure ofnanocrystals lead to the change of their electronic structures. Very recently, nanoscale materials with different electronic structures were utilized in fabricating nanoscale junctions[2]. 　　……     

Quantal transmitter secretion from myocytes loaded with acetylcholine.

It is well known that transmitter secretion requires specialized secretory organelles, the synaptic vesicles, for the packaging, storage and exocytotic release of the transmitter. Here we report that when acetylcholine (ACh) is loaded into an isolated Xenopus myocyte, there is spontaneous quantal release of ACh from the myocyte which results in activation of its own surface ACh channels and the appearance of membrane currents resembling miniature endplate currents. This myocyte secretion probably reflects Ca(2+)-regulated exocytosis of ACh-filled cytoplasmic compartments. Furthermore, step depolarization of the myocyte membrane triggers evoked ACh release from the myocyte with a weak excitation-secretion coupling. These findings suggest that quantal transmitter secretion does not require secretory pathways unique to neurons and that the essence of presynaptic differentiation may reside in the provision of transmitter supply and modification of the preexisting secretion pathway.     

Effect of volatile anesthetics on the circular dichroism of bilirubin bound to human serum albumin

The characteristic circular dichroism of bilirubin bound to human serum albumin undergoes a remarkable sign inversion on addition of halothane, chloroform and other volatile anesthetics. This sign inversion, which is completely reversed by removal of the anesthetic, reflects a pronounced conformational change of the bound ligand; probably a complete inversion of chirality. The observation suggests that association of volatile anesthetics with proteins can markedly alter the internal topography of receptor sites and potentially influence the stereoselectivity of ligand binding.