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121.
Alexandre Genoux Dr. Jorge A. González Dr. Estíbaliz Merino Prof. Dr. Cristina Nevado 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18037-18042
A new family of phosphine-ligated dicyanoarylgold(III) complexes has been prepared and their reactivity towards reductive elimination has been studied in detail. Both, a highly positive entropy of activation and a primary 12/13C KIE suggest a late concerted transition state while Hammett analysis and DFT calculations indicate that the process is asynchronous. As a result, a distinct mechanism involving an asynchronous concerted reductive elimination for the overall C(sp2)−C(sp)N bond forming reaction is characterized herein, for the first time, complementing previous studies reported for C(sp3)−C(sp3), C(sp2)−C(sp2), and C(sp3)−C(sp2) bond formation processes taking place on gold(III) species. 相似文献
122.
Dr. A. Nijamudheen Prof. Dr. Ayan Datta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(7):1442-1487
Transition-metal-catalyzed cross-coupling reactions are central to many organic synthesis methodologies. Traditionally, Pd, Ni, Cu, and Fe catalysts are used to promote these reactions. Recently, many studies have showed that both homogeneous and heterogeneous Au catalysts can be used for activating selective cross-coupling reactions. Here, an overview of the past studies, current trends, and future directions in the field of gold-catalyzed coupling reactions is presented. Design strategies to accomplish selective homocoupling and cross-coupling reactions under both homogeneous and heterogeneous conditions, computational and experimental mechanistic studies, and their applications in diverse fields are critically reviewed. Specific topics covered are: oxidant-assisted and oxidant-free reactions; strain-assisted reactions; dual Au and photoredox catalysis; bimetallic synergistic reactions; mechanisms of reductive elimination processes; enzyme-mimicking Au chemistry; cluster and surface reactions; and plasmonic catalysis. In the relevant sections, theoretical and computational studies of AuI/AuIII chemistry are discussed and the predictions from the calculations are compared with the experimental observations to derive useful design strategies. 相似文献
123.
A greener and efficient method for the synthesis of ynones and 1,3-diynes using copper oxide nanoparticles (CuONPs) doped reduced graphene oxide (CuO@rGO) catalyst under palladium, ligand and solvent free conditions have been developed. The catalyst was subsequently utilized for the synthesis of biologically active 1,5-benzodiazepines in one pot via sequential addition of acyl chlorides, terminal alkynes and o-phenylenediamines. The methodology initially involves in situ formation of ynones which react with o-phenylenediamines in presence of ethanol to afford a wide variety of benzodiazepines. Mild reaction conditions, good to an excellent yield of the products, cheap and recyclable catalyst make this methodology environmentally benign and sustainable. 相似文献
124.
氢解还原法进行环境污染控制 总被引:4,自引:0,他引:4
化学氢解法具有脱卤、脱氮、脱硫、脱芳构化等作用,目前的研究表明该方法对环境中的许多重要污染物都具有还原去除效果,包括卤代化合物、硝基芳香化合物、有机硫化合物、多环芳烃等有机污染物,以及硝酸盐、硫酸盐、氮氧化物、二氧化硫、重金属等无机污染物。为此,本文综述了氢解还原方法降解各类污染物的研究现状,分别介绍了上述各种污染物氢解还原的脱除机理以及影响因素的作用机制,基于绿色化学的要求分析了氢解还原方法的技术优势,从提高氢解效率和节能的角度提出了今后的研究方向。 相似文献
125.
126.
Vadim A. Soloshonok Hironari Ohkura Manabu Yasumoto 《Journal of fluorine chemistry》2006,127(7):930-935
An asymmetric synthesis of (S)- and (R)-3-amino-4,4,4-trifluorobutanoic acid via DBU-catalyzed asymmetric 1,3-proton shift transfer reaction of (Z)-3-[(R)-1-phenylethylamino]-4,4,4-trifluoro-N-[(R)-1-phenylethyl]but-2-enamide has been developed. The intermediate Schiff base (S,R′)-9 was found to be relatively configurationally stable under the highly basic reaction conditions allowing preparation of the target amino acid in high chemical yield and enantioselectivity. This method was demonstrated to be practical for large (>25 g) scale synthesis of the target β-amino acid. 相似文献
127.
We study the nonlinear propagation of dust-ion acoustic (DIA) shock waves in an un-magnetized dusty plasma which consists of electrons, both positive and negative ions and negatively charged immobile dust grains. Starting from a set of hydrodynamic equations with the ion thermal pressures and ion kinematic viscosities included, and using a standard reductive perturbation method, the Kadomtsev-Petviashivili-Burgers (K-P-Burgers) equation is derived, which governs the evolution of DIA shocks. A stationary solution of the K-P-Burgers equation is obtained and its properties are analysed with different plasma number densities, ion temperatures and masses. It is shown that a transition from shocks with negative potential to positive one occurs depending on the negative ion concentration in the plasma and the obliqueness of propagation of DIA waves. 相似文献
128.
建立了一种基于电喷雾电离质谱的丙酮稳定同位素标记对N-糖链进行相对定量的研究方法. 与传统的PNGase F酶水解N-糖链的方法不同,采用非特异性蛋白酶Pronase E对N-糖蛋白进行处理,使N-糖蛋白被酶解为带有一个氨基酸的糖氨酸(Glycan-Asn),为N-糖链引入了一个氨基活性基团,然后用丙酮对氨基进行标记. 用d0/d6丙酮对Ribo B标准糖蛋白的Pronase E酶解产物进行标记,考察了4对d0/d6丙酮标记的Glycan-Asn(Man5~Man8-Asn)在电喷雾电离质谱中的线性、动态范围以及重现性. 结果表明,在10倍动态范围内,相对定量方法有良好的线性关系(R=0.9981)和重现性(CV<8.7%). 并将建立的方法应用于不同含量的鸡卵清白蛋白中,进一步验证了该方法的可行性. 研究结果表明,该方法能准确分析样品中N-糖链的含量,对不同样品中N-糖链进行相对定量. 该方法成本低廉,后处理方法简单方便,适于微量样品通量化分析,对差异糖组的研究有一定的意义. 相似文献
129.
盘状液晶是一类新型有机半导体材料, 盘状二聚体具有新颖的自组织特性. 合成了一系列官能化的盘状液晶单体, 再通过Pd催化端炔自身偶联反应合成了六个二苯基丁二炔桥连的苯并菲盘状液晶二聚体: (RO)5C18H6(O2CC6H4C≡C—C≡CC6H4CO2)C18H6(OR)5 (R=CnH2n+1, n=4~9). 化合物的纯度和结构通过1H NMR, IR和高分辨质谱表征. 二聚体的热失重分析(TGA)结果显示它们有良好的热稳定性, 在370 ℃才开始分解. 化合物的热致液晶性通过偏光显微镜和差视扫描热量法研究, 结果显示所有单体及二聚体化合物均为柱状相液晶, 在室温及以下仍处于液晶相. 单体清亮点随柔链增长呈下降趋势, 而二聚体呈相反趋势. 苯并菲柔链长度和连接基刚性对液晶性都有重要影响. 相似文献
130.