首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   374篇
  免费   21篇
  国内免费   75篇
化学   452篇
晶体学   6篇
综合类   2篇
物理学   10篇
  2024年   2篇
  2023年   3篇
  2022年   8篇
  2021年   15篇
  2020年   16篇
  2019年   15篇
  2018年   11篇
  2017年   17篇
  2016年   20篇
  2015年   15篇
  2014年   22篇
  2013年   48篇
  2012年   39篇
  2011年   19篇
  2010年   16篇
  2009年   22篇
  2008年   27篇
  2007年   23篇
  2006年   14篇
  2005年   19篇
  2004年   16篇
  2003年   14篇
  2002年   24篇
  2001年   9篇
  2000年   5篇
  1999年   7篇
  1998年   7篇
  1997年   2篇
  1996年   2篇
  1995年   4篇
  1994年   3篇
  1993年   1篇
  1992年   1篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1978年   1篇
排序方式: 共有470条查询结果,搜索用时 31 毫秒
371.
以氟代二苯基苯并咪唑为主配体,结合不同的辅助配体乙酰丙酮(对应配合物Ir-1a~Ir-3a)、2-吡啶甲酸(对应配合物Ir-1b~Ir-3b)和2-(5-三氟甲基-2H-[1,2,4]三唑-3-基)-吡啶(tftp,对应配合物Ir-1c~Ir-3c),设计并合成了9个新颖的苯并咪唑铱(Ⅲ)配合物Ir-1a~Ir-3c....  相似文献   
372.
以对氨基苯腈为起始原料,经胺化反应制得N-(4-氰基苯基)甘氨酸(4);4与N-[3-氨基-4-(甲基氨基)苯甲酰基]-N-2-吡啶-β-丙氨酸乙酯(5)经酰胺化后经闭环反应,合成了达比加群酯的关键中间体——3-【【【2-{[(4-氰基苯基)氨基]甲基}-1-甲基-1H-苯并咪唑-5-基】羰基】(吡啶-2-基)氨基】丙酸乙酯,总收率79.6%,其结构经~1H NMR和ESI-MS确证。  相似文献   
373.
利用低价钛试剂促进的2-邻硝基苯基苯并咪唑与原甲酸酯或丙酮或固体光气的反应, 合成了一系列苯并咪唑并[1,2-c]喹唑啉衍生物, 化合物的结构经IR, 1H NMR, MS和元素分析确定, 化合物4c的结构经单晶X射线衍射分析进一步确证. 该方法具有原料易得、操作简便和产率高等优点.  相似文献   
374.
2-azido-1H-benzo[d]imidazole derivatives 1a,b were reacted with a β-ketoester such as acetylacetone in the presence of sodium ethoxide to obtain the desired molecules 2a,b. The latter acted as a key molecule for the synthesis of new carbazone derivatives 4a,b that were submitted to react with 2-oxo-N-phenyl-2-(phenylamino)acetohydrazonoyl chloride to obtain the target thiadiazole derivatives 6a,b. The structures of the newly synthesized compounds were inferred from correct spectral and microanalytical data. Moreover, the newly prepared compounds were subjected to molecular docking studies with DNA gyrase B and exhibited binding energy that extended from −9.8 to −6.4 kcal/mol, which confirmed their excellent potency. The compounds 6a,b were found to be with the minimum binding energy (−9.7 and −9.8 kcal/mol) as compared to the standard drug ciprofloxacin (−7.4 kcal/mol) against the target enzyme DNA gyrase B. In addition, the newly synthesized compounds were also examined and screened for their in vitro antimicrobial activity against pathogenic microorganisms Staphylococcus aureus, E. coli, Pseudomonas aeruginosa, Aspergillus niger, and Candida albicans. Among the newly synthesized molecules, significant antimicrobial activity against all the tested microorganisms was obtained for the compounds 6a,b. The in silico and in vitro findings showed that compounds 6a,b were the most active against bacterial strains, and could serve as potential antimicrobial agents.  相似文献   
375.
以胺甲基苯并咪唑和水杨醛为原料设计合成了一个苯并咪唑衍生物荧光探针,通过荧光分光光度法和紫外分光光度法探寻其对常见阴阳离子的选择性识别性能。研究结果表明,Cu2+对合成得到的苯并咪唑衍生物具有荧光猝灭——"关"的作用,而S2O72-对该荧光猝灭体系具有荧光恢复——"开"的作用。据此,提出了具有实现对Cu2+,S2O72-的荧光"关-开"型探针.  相似文献   
376.
A new dinuclear copper complex, [Cu(C9H11N3)Cl2]2(C18H22Cl4Cu2N6), has been synthesized and characterized by X-ray structure determination. It crystallizes in the triclinic P-1 space group with a = 7.526(3), b = 9.473(4), c = 9.535(3)(A), α = 117.214(10), β = 108.251(9), γ = 91.560(6)°, V = 562.3(4)(A)3, Z = 1, Mr = 591.30, F(000) = 298, Dc = 1.746 g/cm3, μ(MoKα) = 2.385 mm-1, the final R = 0.0577 and wR = 0.1248 for 2188 unique reflections with 1629 observed ones (Ⅰ> 2σ(Ⅰ)). In the title complex, each copper(Ⅱ) atom is located at the center of a distorted trigonal bipyramid of five coordination atoms (two nitrogen and three chlorine atoms). Two copper(Ⅱ) atoms were bridged by two chlorine anions (Cl(2) and Cl(2a)) to form a Cu(Ⅱ)-Cu(Ⅱ) binuclear entity with the distance between two copper(Ⅱ) atoms of 3.398 (A).  相似文献   
377.
378.
陈芳  胡珍珠 《合成化学》2006,14(5):480-483
在甲醇中合成了3种稀土-组氨酸-苯骈咪唑配合物Re(H is)m(B IM)(C lO4)3.nH2O(Re=La,m=3,n=6;Re=Nd,Y,m=2,n=8),其结构经UV,IR,TG-DTA,摩尔电导,化学分析和元素分析表征。生物活性实验表明:配合物对大肠杆菌、金黄色葡萄球菌和霉菌均有不同程度的抑菌作用,且菌液浓度越低,配合物的抑菌效果越好。  相似文献   
379.
Three novel small organic heterocyclic compounds: 2-(1,2-diphenyl)-1H-benzimidazole-7-tert-butylpyrene (compound A), 1,3-di(1,2-diphenyl)-1H-benzimidazole-7-tert-butylpyrene (compound B), and 1,3,6,8-tetra(1,2-diphenyl)-1H-benzimidazolepyrene (compound C) were synthesized and characterized for possible applications as blue OLED emitters. The specific molecular design targeted decreasing intermolecular aggregation and disrupting crystallinity in the solid-state, in order to reduce dye aggregation, and thus obtain efficient pure blue photo- and electroluminescence. Accordingly, the new compounds displayed reasonably high spectral purity in both solution- and solid-states with average CIE coordinates of (0.160 ± 0.005, 0.029 ± 0.009) in solution and (0.152 ± 0.007, 0.126 ± 0.005) in solid-state. These compounds showed a systematic decrease in degree of crystallinity and intermolecular aggregation due to increasing steric hindrance, as revealed using powder X-ray diffraction analysis and spectroscopic studies. An organic light-emitting diode (OLED) prototype fabricated using compound B as the non-doped emissive layer displayed an external quantum efficiency (EQE) of 0.35 (±0.04)% and luminance 100 (±6) cd m−2 at 5.5 V with an essentially pure blue electroluminescence corresponding to CIE coordinates of (0.1482, 0.1300). The highest EQE observed from this OLED prototype was 4.3 (±0.3)% at 3.5 V, and the highest luminance of 290 (±10) cd m−2 at 7.5 V. These values were found comparable to characteristics of the best pure blue OLED devices based on simple fluorescent small-molecule organic chromophores.  相似文献   
380.
《先进技术聚合物》2018,29(6):1834-1842
Fabrication, characterization, and properties of novel poly(benzimidazole‐amide)/functionalized ZnO nanocomposites (PBIA/APS‐ZnO NCs) were investigated. At first, an aromatic PBA containing 3 imidazole units per repeat unit was synthesized by direct polycondensation of 1,3‐bis(5‐carboxylic acid‐2‐benzimidazole)benzene (BCAB) with 5‐(2‐benzimidazole)‐1,3‐phenylenediamine (DAMI) with good yield as a polymeric matrix. The periphery of zinc oxide nanoparticles (ZnO NPs) was modified with 3‐aminopropyltriethoxysilane (APS) to have a better dispersion NPs and enhancing interactions between nanoparticles and PBIA matrix. Different percentages of functionalized NPs (0, 4, 8, and 12 wt.%) were then embedded in PBA matrix through ultrasonic irradiation technique. Fourier transform infrared and thermo‐gravimetric analysis (TGA) confirmed that APS was successfully attached on the ZnO NP surface. The obtained NCs were characterized by means of Fourier transform infrared, X‐ray diffraction, scanning electron microscopy, and TGA. The TGA of the PBIA/APS‐ZnO NCs showed the enhancement in the thermal stability in comparison with the neat PBIA and that this increase is higher when the NP content increases. Scanning electron microscopy analyses of NCs revealed that the dispersion of APS‐ZnO NPs was uniformly done in the PBIA matrix.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号