除草剂最近的发展

一、各国除草剂应用现状化学除草剂的应用不仅是保证农作物不受杂草危害的手段,而且是节省劳动力的一项重要措施。最近各国曾提出使用除草剂可以不必翻耕土地就能达到从播种到收获的效果,如果这种新措施能普遍推广,它将打破传统的耕作制度,掀起农业生产上的一个革命。由于除草剂具有节省劳动力的突出优点,近年来,它的发展速度是其他农药所赶不及的。美国除草剂生产增长速度超过了杀虫剂和杀菌剂。英国除草     

气相色谱检测尿液中丁草胺

农药中除草剂的使用在农业作业区非常普遍,尤其是以丁草胺为代表的酰胺类除草剂作为防治一年生禾本科杂草的特效除草剂应用十分广泛.由丁草胺引起的投毒、自杀和误服等中毒案件近年来也呈上升趋势.目前,关于酰胺类除草剂的研究主要集中在对其各种制剂~([1])和环境残留~([2,3])的检验方面,而关于中毒者体内检材中酰胺类除草剂的分析研究却少见报道.因此,研究生物样品中酰胺类除草剂的分析检验方法具有一定的理论意义和实际应用价值.本研究建立了尿液中丁草胺的液液萃取-气相色谱检测方法.本方法将有助于对酰胺类除草剂中毒案件的检验研究.     

液相色谱-电喷雾串联四极杆质谱法测定植物源性食品中氟草烟的残留量

1引言氟草烟(Fluroxypyr)的商品名称为使它隆(Starane),化学名称为4-氨基-3,5-二氯-6-氟吡啶-2-氧乙酸。氟草烟是一种内吸传导型苗后除草剂,对小麦、大麦、元麦、玉米田间及果园的多种杂草有良好的防除效果。近年来欧盟、美国和日本对部分谷物、蔬菜、水果等植物产品和动物源性     

对羟基苯丙酮酸双加氧酶(HPPD)的结构及其吡唑类除草剂的最新研究进展

对羟基苯丙酮酸双加氧酶(EC 1.13.11.27,HPPD)是重要的除草剂靶标.以HPPD为靶标的除草剂具有高效、低毒、作物安全性高、不易产生抗性、环境相容性好及对后茬作物安全等一系列优点.结合最新的研究进展,详细综述了HPPD的结构,并针对吡唑类HPPD除草剂的作用模式、在生物体内的作用机制和代谢途径以及研究现状进行了总结与分析.     

单原子材料在电化学生物传感中的研究进展

电化学传感器具有响应速度快、 专一性强及准确性高等特点, 已成为生物传感快速检测的重要发展方向之一, 但目前难以达到对单个生物分子的检测水平, 这主要受限于作为核心部件的探针材料. 单原子材料由于其简单明确的原子局域结构, 且具有媲美于生物酶的统一活性位点, 是一种极具潜力的探针材料, 因此受到了广泛关注. 本文综合评述了具有均一局域配位环境的单原子材料的合成, 以及其在电化学生物传感中的应用, 并对单原子材料在未来电化学生物传感中面临的挑战和机遇进行了展望.     

有机底物的分子识别

有机底物的分子识别陆国元（南京大学化学系２１００９３）分子识别在生物和生命活动中起中心作用。生物酶之所以高效专一催化生化反应，首先是由于酶对底物的精确的分子识别。８０年代中期以来，对中性有机分子，尤其是生物分子的人工分子识别研究日趋活跃，并已导致氨基...     

高效液相色谱法测定棉花中3种脱叶剂的残留量

<正>棉花作为纺织品的主要原材料,在纺织工业领域起着支柱作用。在棉花的生长过程中使用农药不可避免。脱叶剂作为一种植物生长调节剂,能够促使植物叶子提前脱落,有利于农业的机械化[1-2]。棉花中使用的脱叶剂农药主要有噻节因、噻苯隆、敌草隆、脱叶磷和乙烯利等,常用的脱叶剂农药商品主要为一种或几种成分的混合物。由于脱叶剂在棉花收获前期使用,与杀虫剂和除草剂相比更易在棉花纤     

磷酰化与非磷酰化蛋氨酸水溶液的脉冲辐解研究

蛋氨酸能快速清除导致辐射损伤的·OH自由基，在放射生物学上是一类很重要的辐射保护剂，因此，引起了人们的广泛关注［l一到．生物大分子的磷酸化作用亦越来越受到重视，特别是近年来基因调控研究发现，许多蛋白质和生物酶只有被磷酸化氧化才具有生理活性，文献［4－6］报导蛋     

基于DNA定向固定化技术构建毛细管固定化酶微反应器的研究进展

生物酶影响着物质代谢和质能转换等生命活动,生物体内某些酶的活性变化会导致疾病的发生。发展新型的酶分析方法对深刻理解生物代谢过程、疾病诊断和药物研发等具有重要意义。毛细管电泳（CE）具有分离效率高、分析速度快、操作简单和样品消耗少以及可与多种检测手段联用等优点,在酶分析研究中越来越受到关注。CE酶分析主要包括离线和在线两种模式,其中,固定化酶微反应器与毛细管电泳联用（CE-IMER）的在线酶分析已经成为主要的酶分析方法之一。CE-IMER充分结合了固定化酶和CE的优势,将游离酶固定在毛细管内,不仅可以显著提高酶的稳定性和重复使用性,而且可以实现纳升规模溶液的自动化酶分析,进而显著降低酶分析成本。目前已有大量方法制备IMER用于CE酶分析,然而如何构建性能良好、可再生使用、酶固载量大、自动化程度高的CE-IMER一直是该领域重点研究的问题。DNA定向固定化技术（DDI）可以充分利用DNA分子的碱基互补配对（A-T,C-G）,在温和的生理条件下特异性固定生物大分子。由于短链双螺旋DNA分子具有较强的机械刚性和物理化学稳定性,通过DDI将酶固定在载体表面,有利于降低传质阻力,提高酶与底物的接触能力,进而促进酶促分析过程。该文主要综述了利用DDI构建新型IMER在CE酶分析中的应用现状,并对其未来发展进行了展望。     

苯氧乙酸类化合物的合成研究

二苯醚型苯氧基乙（丙）酸类除草剂是一类用于禾本科杂草的除草剂，具有选择性强，内吸迅速，对环境危害小和使用安全等优点，被广泛应用于农林业生产。为了寻找更高效、低毒和低残留的除草剂，本文以相应结构的取代羟基二苯醚为骨架，以氯代乙酸乙酯为原料，经亲核取代反应制得此类化合物。在反应过程中为提高产率，加入了相转移催化剂；由于羟基二苯醚类化合物在空气中容易被氧化，在反应过程中采用氮气保护，得到了较纯产物，产率较高。共合成了苯氧基苯氧基乙酸乙酯类化合物5个，目标物的合成路线如下：     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.