利用气流仪快速测定纤维细度方法的研究

本文对利用气流仪测定棉纤维和化学纤维细度的方法进行了新的探索,提出了用不固定称量法测定的棉纤维细度与标准测试方法之间的换算式;提出了用改变试样重量以保持空隙率不变的方法,使一台气流仪能测定各种圆形截面化学纤维的细度。最后并对气流仪测定非圆形截面化学纤维细度的可能性和必须满足的条件进行了讨论。     

求解蛋白质折叠问题的改进PERM算法

在学习PERM算法的基础上，指出了影响PERM算法效率的关键因素，进而提出了一种改进的PERM算法——IPERM(Improved PERM)．计算结果表明，IPERM的计算效率优于PERM算法，并且远高于基于蒙特卡罗的MSOE算法和基于重要性抽样的SISPER算法．     

A Coordination Model of Gene Sequences for SARS-CoV and its Receptor

IntroductionFrom the emergence of SARS CoV, manystudies havebeen done on its biological medicine aspects, such aspathogeny characteristics, mechanisms of causing disease,clinic diagnosis and treatment, bacterin development andthe spreading rules. At the level of molecule biology,studies have been done on its genome sequences characteristics, structures and functions of the translatedproteins, and the evolution relationships in sequences[1 5].The caus…     

充分开发利用农林副产品搞活农村经济

本文概述了我省农、林副产品的丰富资源及其开发前景,认为利用木屑、棉子壳、稻草、蔗渣等大力开发食用菌生产,是一种潜力巨大的再生性农业,可使农村尽快富裕起来.利用饼、粕及其他副产品做饲料,利用轻工业、食品工业的副产品做原料,发展蛋白质饲料生产,前景十分可观.     

排序融合算法在校园网搜索引擎中的应用

网页排序技术是搜索引擎的核心技术之一. 校园网搜索引擎是指以一个校园网内的Web网页为搜索内容的搜索引擎. 由于校园网相对于互联网和内联网的特殊性,各种启发式条件对校园网网页排序优化的影响及排序融合技术在校园网搜索引擎的作用是研究的重点. 实验结果表明各个启发式条件的影响和实验数据集有关,而不同启发式条件组合经过排序融合后所获得的查全率差别很大(2%～48%). 查全率大于35%的启发式条件组合至少包含4个启发式条件,即校园网搜索引擎的排序需要依据数据集综合考虑多个启发式条件的排序结果. 排序融合技术是校园网搜索引擎具有良好的查全率的必要技术之一. 基于排序融合技术的网页排序模块已经应用于清华大学校园网搜索引擎中.     

猪血蛋白粉营养的实验研究

猪血蛋白粉是由干燥猪血粉(或新鲜猪血)经生物化学改造、脱色,加工制成的一种谷黄色粉状蛋白质制品.经多项营养分析测试结果,含蛋白质90.1%及多种元素成分,富含铁元素为193.5—200.0mg/100mg.含18种人体生长需要的氨基酸成分,其中8种人体必需氨基酸俱全.以鸡蛋蛋白质为参考模式,并与FAO/WHO标准模式进行比较分析,测得化学分为21.26%,氨基酸分为25.35%,必需氨基酸指数为56.69%.参照AOAC方法通过28天大白鼠喂养试验结果表明,猪血蛋白粉对幼龄大白鼠具有明显的促生长作用.通过体内氮平衡试验表明猪血蛋白粉对实验大白鼠FE、PER、BV、TD、NPR、NPU、NB等7项营养代谢指标的测定结果提示猪血蛋白粉具有良好的体内消化率和利用率.不失为一类具有良好开发前景的廉价高蛋白动物性氮源.     

Guanylate cyclase in human platelets with different aggregability

Summary The activity of human platelet guanylate cyclase, and the activation of the enzyme by sodium nitroprusside were decreased in platelets with increased aggregability; these platelets were obtained from diabetes mellitus patients. Anomalies in guanylate cyclase activity and ADP-induced aggregation were more pronounced in platelets from subjects with type II than those with type I diabetes.     

Modulation of protein kinases and phosphoprotein phosphatases by a small acidic protein from bovine brains

Summary A small, acidic and heat-stable protein was purified from bovine brains by column chromatography on DEAE-cellulose, Bio-Gel HTP, Affi-Gel phenothiazine and Sephadex G-75. This protein stimulates megamodulin-dependent protein kinase I from brains and phosphoprotein phosphatases from either brain or yeast. However, it inhibits cyclic AMP-dependent protein kinases from skeletal muscle.Acknowledgments. This work was supported by a grant (RR-08229) from the National Institutes of Health, USA. W.N. Kuo is a recipient of a Distinguished Faculty Scholar Award from United Negro College Fund, Inc., USA.     

Review¶Psychrophilic enzymes: molecular basis of cold adaptation

Psychrophilic organisms have successfully colonized polar and alpine regions and are able to grow efficiently at sub-zero temperatures. At the enzymatic level, such organisms have to cope with the reduction of chemical reaction rates induced by low temperatures in order to maintain adequate metabolic fluxes. Thermal compensation in cold-adapted enzymes is reached through improved turnover number and catalytic efficiency. This optimization of the catalytic parameters can originate from a highly flexible structure which provides enhanced abilities to undergo conformational changes during catalysis. Thermal instability of cold-adapted enzymes is therefore regarded as a consequence of their conformational flexibility. A survey of the psychrophilic enzymes studied so far reveals only minor alterations of the primary structure when compared to mesophilic or thermophilic homologues. However, all known structural factors and weak interactions involved in protein stability are either reduced in number or modified in order to increase their flexibility.     

Corpus cardiacum — a target for azadirachtin

Summary Azadirachtin A, an insect growth inhibitor derived from neem seed, when injected at a physiological dose, inhibits the hormonally controlled ovarian development inLocusta migratoria. Its tritiated dihydro derivative concentrates more in the corpus cardiacum than in the brain. Translocation and release of the neurosecretory proteins labeled with L-[³⁵S]-cysteine in the corpus cardiacum is very poor in locusts under azadirachtin stress. It is concluded that azadirachtin may influence the release of trophic hormones from the corpus cardiacum leading to alterations in timing and titer of morphogenetic hormone pools.