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101.
102.
The mesopores of a monolithic silica column are very important and useful for chromatographic separation since they can offer sufficiently large surface area. In this paper, a novel method with the assistance of an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate ([bmin]BF4)) was developed for the preparation of a C18-modified monolithic silica column for the first time, in which, the through pores and mesopores were formed simultaneously during the sol-gel reaction. The method is effective to simplify the preparation process of the silica-based monolithic columns. The factors influencing the sol-gel process, including the content of methanol and pH, were studied. The chromatographic performance of the prepared monolithic column was evaluated by the separation of alkylbenzenes. 相似文献
103.
利用纳秒级激光光解瞬态吸收光谱研究了联苯甲酰(BZ)在离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim][BF4])与乙腈(MeCN)混合体系中的光化学反应行为. 考察了探针分子BZ存在下[bmim][BF4]/MeCN比例对体系中化学反应动力学的影响. 实验发现: 在N2饱和条件下, BZ溶液经激光辐照后产生的激发三线态3BZ*遵循一级反应动力学规律衰减. 离子液体(IL)相对比例增加对3BZ*瞬态吸收峰的位置和强度没有产生明显影响. 但离子液体体积分数VIL的变化对[bmim][BF4]/MeCN混合溶剂中光诱导电子转移的影响却非常显著, 总体上电子转移产生的自由基的表观生成速率常数kgr随[bmim][BF4]的VIL增大而减小. 在[bmim]BF4]比例足够大的情况下, 3BZ*与三乙胺或四甲基对苯二胺之间的电子转移被抑制. 相似文献
104.
Lithium tetrafluoroborate has been demonstrated for the first time to be an efficient catalyst in intermolecular aza-Michael addition aromatic amines to electron deficient alkenes. Suitability of the same catalyst in intramolecular aza-Michael addition leading 2-aryl-2,3-dihydroquinolin-4(1H) ones has also been described. 相似文献
105.
106.
用激光闪光光解方法研究了杜醌(DQ)在吡啶型离子液体N-丁基吡啶四氟硼酸盐([BPy][BF4])与乙腈(MeCN)组成的共混溶剂中的光化学反应机理与动力学. 实验结果表明, 离子液体[BPy][BF4]对混合体系中杜醌激发三线态(3DQ*)的瞬态吸收峰位置和吸光度大小都没有产生明显影响. 在N2饱和条件下, 无论是在乙腈溶液中还是在[BPy][BF4]/MeCN混合溶液中3DQ*的衰减都遵循一级反应动力学规律. 而[BPy][BF4]的存在对3DQ*与三乙胺(TEA)之间的电子转移影响显著. 随着[BPy][BF4]/MeCN 体系中离子液体比例的增加, 杜醌三线态3DQ*与TEA间的瞬态反应机理没有改变, 但它们之间的光诱导电子转移反应速率和生成自由基的量子产额逐渐降低, 通过改变离子液体的比例可以调节该体系中光诱导电子转移反应的速率和效率. 相似文献
107.
Temperature dependence of viscosity and relation with the surface tension of ionic liquids 总被引:1,自引:0,他引:1
Viscosities of ionic liquids were correlated with two linear relations. The first one presents the temperature dependence of imidazolium-, pyridinium-, pyrrolidinium-, quaternary ammonium-, and nicotinium-based ionic liquids with high accuracy. The second one is a linear relation between logarithm of surface tension and fluidity involving the characteristic exponent ?, and fits the ionic liquids uniquely with ? = 0.30. Our previously measured surface tension data of ionic liquids and literature's were used in this study. The dependence of surface tension–fluidity relation of the imidazolium-based ionic liquids on the anion type is likely disappeared as alkyl chain length increases. 相似文献
108.
WANG Jingyang ZHANG Meng XU Xiaodong FENG Jing WANG Yanli ZHANG Milin HAN Wei CHEN Yitung TIAN Guoxin 《高等学校化学研究》2018,34(1):8-12
A new transition metal complex, [Cu(N-MeIm)4(BF4)2](N-MeIm=N-methylated imidazoles, BF4= tetrafluoroborate), was synthesized via the solvothermal method in ionic liquid. The ionic liquid acts as thermal decomposition reaction medium, soft temple agent and ligand compound. The central Cu(II) ion is coordinated by four N atoms from four N-methylated imidazole ligands, and the four N-methylated imidazole rings are perpendicular to each other. The crystal structure of [Cu(N-MeIm)4(BF4)2] was determined by single crystal X-ray diffraction. The results of thermogravimetry(TG) and Fourier transform infrared spectrometry(FTIR) analyses were in accordance with that of crystal structure. The complex showed strong ligand-based absorbance with maximum wavelength at 208 and 231 nm, which are attributed to π-π* transition of the N-methylated imidazole ligands. 相似文献
109.
利用循环伏安法(CV)和现场红外光谱电化学技术研究了2-氨基-3-氯-1,4-萘醌(ACNQ)在1-丁基-3-甲基咪唑四氟硼酸盐(BMIMBF4)中电化学捕获CO2的机理.研究结果表明,当体系中不存在CO2时,ACNQ在BMIMBF4中经历可逆的两步一电子过程;当体系中引入CO2时,电化学还原过程中形成的二价阴离子(ACNQ2-)作为亲核试剂,可攻击CO2的亲电子碳中心,形成稳定的CO2加合物.对电化学捕获CO2的化学计量进行了评估,结果表明,1摩尔的ACNQ2-可捕获1摩尔的CO2.结合B3LYP方法在6-311++G**水平上计算分析了反应中CO2加合物可能的结构. 相似文献
110.
Nitrosonium ions are versatile and mild oxidants, which were successfully employed in organic transformations. The applications cover different fields, such as the functionalization of carbon-carbon and carbon-heteroatom bonds, functionalization of unsaturated bonds and the oxidative coupling of arenes, catalyzed by nitrosonium ions. Due to the ability of nitrosonium ions to modify various types of bonds with different modes of action, a variety of applications has been established, which addresses current challenges in organic chemistry research. By considering additional points, such as safety of reagents, by-product formation, employed solvents and energy consumption, several aspects of green and sustainable chemistry can be addressed. Within this review, synthetic applications of nitrosonium ions under transition metal-free reaction conditions are summarized. 相似文献