紫外线吸收剂UV－981和UV－1009的性能和应用研究

研究了ＵＶ－９８１和ＵＶ－１００９高分子量化二苯甲酮类紫外线吸收剂的红外吸收光谱、紫外吸收光谱及其耐热性、毒性、耐水性、耐候性及相容性。实验结果表明其加工应用性能均优于相应的低分子产品ＵＶ－５３１，是比较理想的高分子量化二苯甲酮类光稳定剂。     

B90催化剂上丁烯氧化脱氢的反应动力学─一一种简便的建立化学动力学方程的方法

采用简便的建立化学反应动力学方程的方法，研究了Ｂ９０催化剂上丁烯氧化脱氢制丁二烯反应的动力学，即先在一较低温度下，用微分法拟合得到化学反应动力学方程中的浓度项，然后改变反应温度，求算不同温度下的反应速率常数。采用这个简便方法，只需较少的实验，即可求得该反应体系中的丁烯转化速率方程式。     

Combinatorial Design of Some Database Application Technologies Based on B/S

Evolving From principal-subordinate structure of C /S to flexible multileveled distributed structure, i.e. B/S architecture so as to form a wide, distributed and orderly Internet/Intranet integrated management inf ormation system, is the trend of development of application software of the whol e world. Advantages and disadvantages of the two modes: C/S and B/S are compared . It is pointed out that at present onefold B/S mode cannot yet fully fullfil th e demands of some complicated data processing, inform...     

紫外线辐射对柑桔过氧化物酶活性和电频率特性的影响

介绍了紫外线辐照柑桔后,柑桔过氧化物酶活性等生理参量和频率特性等物理参量随贮藏时间变化的实验结果,并对结果作了简单分析.结果表明:适当剂量的紫外辐照,可以降低柑桔的过氧化物酶活性,使柑桔电学频率特性等物理参量尽可能保持贮藏初期的特点,延缓柑桔内部结构和所含成分的变化,收到一定的保鲜效果.     

文蛤(Meretrix Meretrix)凝集素(MML)的初步研究——Ⅰ.MML在文蛤体内的分布及纯化

在文蛤(Meretrix Meretrix)体内具有血球凝集活性的凝集素(简称MML),经实验证实仅分布于文蛤外套腔液中。向外套腔液中加入固体硫酸铵达40％时,可使99％的MML沉淀。用不同饱和度的硫酸铵溶液依次对上述沉淀进行抽提,得到MML粗制品溶液,其比活比原始外套腔液提高了约9.95倍,总活力回收达48％。最后用自制的人血浆糖蛋白一Sepharose 4 B亲合层析柱可将上述MML粗制品的比活再提高400多倍。结果与原始外套腔液比较,MML终产品的比活总共提高了4313倍,总活力回收达44.8％,在电泳鉴定时显示出单一的区带。     

A_a、B_b、B_l型缩聚反应体系的溶胶—凝胶分配

本文用Gordon生成函数法对A_a、B_b、B_1型反应体系的溶胶——凝胶分配进行了理论分析,得到了A_a、B_b、B_1体系的溶胶分数(S)、凝胶反应程度(P'_b),总反应程度(P_b)之间的关系,讨论了凝胶化范围,并用实验进行了验证。     

Immune responses to DNA vaccines

DNA vaccines, based on plasmid vectors expressing an antigen under the control of a strong promoter, have been shown to induce protective immune responses to a number of pathogens, including viruses, bacteria and parasites. They have also displayed efficacy in treatment or prevention of cancer, allergic diseases and autoimmunity. Immunologically, DNA vaccines induce a full spectrum of immune responses that include cytolytic T cells, T helper cells and antibodies. The immune response to DNA vaccines can be enhanced by genetic engineering of the antigen to facilitate its presentation to B and T cells. Furthermore, the immune response can be modulated by genetic adjuvants in the form of vectors expressing biologically active determinants or by more traditional adjuvants that facilitate uptake of DNA into cells. The ease of genetic manipulation of DNA vaccines invites their use not only as vaccines but also as research tools for immunologists and microbiologists. Received 26 October 1998; received after revision 3 December 1998; accepted 3 December 1998     

The pleiotropic functions of aspirin: mechanisms of action

Recent studies have suggested that aspirin and aspirin-like compounds have a variety of actions in addition to their well-studied ability to inhibit cyclooxygenases. These actions include inhibition of the uncoupling of oxidative phosphorylation, decreases in adenosine triphosphate stores, increases in extracellular adenosine, downregulation of the expression and activity of inducible nitric oxide synthetase, inhibition and/or stimulation of various mitogen-activated protein kinase activities and inhibition of nuclear factor binding κB site (NF-κB) activation. Moreover, aspirin-like compounds have recently been shown to have previously unappreciated clinical and biological effects, some apparently independent of cyclooxygenase. In this review we discuss the various mechanisms of action of aspirin-like compounds and their relevance to clinical disease and therapy. Received 1 February 1999; received after revision 1 April 1999; accepted 7 May 1999