采用多种农药治理抗性的理论、事实和建议

为延缓抗性发展而采用农药混用措施并不是一种新的想法,但最近越来越受到人们的关注.几种农药的合用包括有:"序列"(Sequences)、"混用"(mixtunes)、"轮用"(rotations)和"嵌入"(mosaics)等用法."序列"用法是指连续使用一种农药(A)直至抗性产生,然后再用另一种农药(B),即AAABBB;"混用"是指对目标物同时接触混合的多种药剂;"轮用"是指几种药剂之间轮换使用,即ABABAB或AABBAABB;"嵌入"用法是指空间上使用的变化,即相邻的区域同时受到不同药剂的处理.     

Induction of DNA-double-strand breaks by auger electrons from 99mTc complexes with DNA-binding ligands

The potential of certain Auger electron emitting nuclides for systemic radiotherapeutic applications has recently gained much attention. In particular, the ability of several nuclides, including 111In, 125I, and 123I, to induce DNA double-strand breaks (dsb), a good indicator of cytotoxicity, has been extensively studied. However, this ability has never previously been shown experimentally for 99mTc, which, besides the well-known gamma radiation that is used for diagnostic applications, also emits an average of 1.1 conversion electrons and 4 Auger or Coster-Kronig electrons per decay. Owing to the short range of Auger electrons, the radionuclide needs to be located very close to the DNA for dsb to occur. We synthesized two cationic 99mTcI-tricarbonyl complexes with pendant DNA binders, pyrene and anthraquinone. The X-ray crystal structures of the two complexes could be elucidated. Linear dichroism and UV/Vis spectroscopy revealed that the complex with pyrene intercalates DNA with a stability constant, K, of 1.1 x 10(6) M(-1), while the analogous complex with anthraquinone interacts with DNA in a groove-binding mode and has an affinity value of K=8.9 x 10(4) M(-1). We showed with phiX174 double-stranded DNA that the corresponding 99mTc complexes induce a significant amount of dsb, whereas non-DNA-binding [TcO4]- and nonradioactive Re compounds did not. These results indicate that the Auger electron emitter 99mTc can induce dsb in DNA when decaying in its direct vicinity and this implies potential for systemic radiotherapy with 99mTc complexes.     

用电泳涂料组合物涂装金属底材及其固化方法

本发明提供了液态电泳涂料组合物施工于金属底材时的干燥方法,包括下列步骤:(a)对电泳涂料组合物同时加以红外辐射及暖空气流,时间至少1min,在电泳涂层表面的气流速度<4m/s,金属底材升温速度为0.25～2℃/s,使底材最高金属温度为35～140℃;及(b)对电泳涂料组合物同时加以红外辐射及热空气流,时间至少2min,金属底材升温速度为0.2～1.5℃/s,使底材的最高金属温度为160～215℃,从而在金属底材表面形成     

高温使用性能获得改进的三元乙丙橡胶胶料

虽然三元乙丙橡胶(EPDM)属于耐热性弹性体,但其耐热性还可通过选用一种特殊的聚合物结构以及适当的添加剂,如:氯磺化聚乙烯和三氧化二锑获得进一步改进。适当的防老剂也能提高三元乙丙胶硫化胶的耐高溫性能。     

固定式管板换热器的一个分析方法

本文所述固定式管板换热器的分析方法是利用一个轴对称壳体分析的计算机规程或有限元分析的计算机规程来进行的,其管束被模拟为一当量的弹性基础。只有仔细地确定了边界条件之后,在本文中所述的方法采用计算机规程才有可能。方法可以扩大用于带转角,法兰等的壳体。附有数值例题以帮助设计工程师应用此方法。     

近代湿法磷酸工艺技术概况

湿法磷酸的生产从1870年以后就已经工业化了,这种酸主要是用作肥料生产的中间产品。目前大部分开工的湿法磷酸厂都是二水物法,因为二水物法设计和操作都比较简单。其他工业上使用的方法还有半水物法,半水二水物联合法,或者无水物法。所有湿法磷酸工艺操作的基本方法大致都一样,即磷酸盐岩用硫酸酸化,生成的硫酸钙以及其他不溶性杂质通过过滤和磷酸分离。各种不同类型的工艺方法在本文中作了比较。最近的研究与进展主要集中在二水物法,半水物法或半水二水物联合法以及酸的     

碳纤维与复合材料的回顾(第一部分)

在论文将分为两部分,目的是要回顾碳纤维及其原丝的生产技术、纤维结构及其主要性能(第一部分).并总结目前树脂基或水泥基碳纤维复合材料的现状(第二部分)。     

分子内敏化鎓盐的合成及光敏性研究

二芳基碘鎓盐和三芳基硫鎓盐是阳离子聚合的光引发剂和光敏产酸物,但他们在300nm以上的光吸收很低,限制了对紫外光的利用效率。为解决此问题,本文合成了一些新的碘鎓盐和硫鎓盐,并用凝胶时间方法考察了它们的光引发效率。实验结果表明,2-苯硫基甲基,2′,4′-二甲基二苯碘鎓盐和9-蒽丙基,二苯基硫鎓盐具有特别高的光引发效率,这归之于光照时这些鎓盐发生了分子内电荷转移反应,即发生了分子内敏化。9-蒽丙基二苯硫鎓盐分子中的蒽基(An)是电子给体也是敏化基团,光照时可发生如下反应:     

Thioglycolate-elicited rat macrophages exhibit alterations in incroporation and oxidation of fatty acids

Incorporation and oxidation of fatty acids (FA) were investigated in resident and thioglycolate-clicited (TG-elicited) rat macrophages (Mϕ). Both cell types presented a time-dependent incorporation of [¹⁴C]-labeled palmitic acid (PA), oleic acid (OA), linoleic acid (LA), and arachidonic acid (AA) up to 6h. The total amount of [¹⁴C]-FA incorporated by resident Mϕ after 6 h was: AA>PA=LA>OA. TG-elicited cells presented a 50% reduction in the incorporation of LA, PA, and AA, whereas that of OA remained unchanged as compared to resident Mϕ. The FA were oxidized by resident Mϕ as follows: LA>OA>PA>AA. TG elicitation promoted a reduction of 42% in LA oxidation and a marked increase in AA oxidation (280%). The increased oxidation of AA in TG-elicited cells may account for the lower production of prostaglandins in Mϕ under these conditions. The full significance of these findings for Mϕ function, however, remains to be examined.     

硫黄促进剂体系用非迁移性助活性剂低聚物

本文报道的研究目的是开发迟效性促进剂硫黄硫化体系用助活性剂。这种添加剂可以提高交联键的形成速率而很少改变或者根本不改变混炼胶或其硫化胶的抗焦烧性性能或其他性能。本研究的另一目的是要设计一种具有慢效作用的硫化体系助活性剂。它不会从橡胶贴合制品(如轮胎)的一个部分迁移或者扩散到相邻的部分中去。本研究的初期阶段曾致力于评价一系列用作乳聚丁苯橡胶(SBR)硫化助活性剂的高分子量乙烯基吡啶二烯烃乳液共聚物。这些共聚物在室温下绝大部分是橡胶态的,它们都很容易分散于丁苯橡胶混炼胶中。使用乙烯基吡啶共聚物得到的初步结果是令人鼓舞的。