全文获取类型
收费全文 | 288篇 |
免费 | 18篇 |
国内免费 | 58篇 |
专业分类
化学 | 337篇 |
晶体学 | 7篇 |
物理学 | 20篇 |
出版年
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 18篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 21篇 |
2014年 | 23篇 |
2013年 | 29篇 |
2012年 | 15篇 |
2011年 | 20篇 |
2010年 | 21篇 |
2009年 | 20篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 14篇 |
2005年 | 16篇 |
2004年 | 11篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有364条查询结果,搜索用时 15 毫秒
121.
YANG Lina ;ZHAO Xiang-Hua ;ZHOU Hong-Ping ;WU Jie-Ying ;YANG Jia-Xiang ;SHAO Guo-Quan ;CHENG Le-Hua ;TIAN Yu-Peng 《结构化学》2008,27(2):143-148
A novel bis(β-diketonate) derivate, 3,6-bis(4,4,4-trifluorobutane-1,3-dione)-9-n- butylcarbazole 1, was synthesized and structurally characterized by single-crystal X-ray diffrac- tion. The crystal belongs to the monoclinic system, space group P2 1/c with a = 10.961(6), b = 22.942(13), c = 9.408(6)A, α = 90, β = 109.663(9), y = 90°, V = 2228(2)A^3, Z = 4, Dc = 1.489 g/cm^3, C24H19F6NO4, Mr = 499.40, F(000) = 1024 and μ = 0.134 mm^-1. The structure was refined to the final R = 0.0699 and wR = 0.1627 for 3744 independent reflections (Rint = 0.1288) and 1349 observed reflections (I 〉 2σ(I)). Compound 1 consists of carbazole unit and two terminal diketonate groups, in which carbazole and its two adjacent diketonate rings are almost coplanar. Moreover, compound 1 was characterized with IR, elemental analysis, IH NMR, MS, electronic absorption, and single-photon fluorescence. 相似文献
122.
Yingliang Liu Shengang Xu Jianghui Li Yuanrong Xin Guoxin Zhao Baoxian Ye Shaokui Cao 《先进技术聚合物》2008,19(7):793-800
Two series of conjugated polymers with a carbazole moiety were synthesized by Knovenagel and Wittig condensations. The chemical structure, thermogravimetric, photophysical and electrochemical properties of the polymers were characterized by 1H‐NMR, IR, GPC, TG, UV‐vis, FL, and CV. The results indicated that PBM is the most thermally stable one and PBP is the most thermally instable one. The absorption and emission properties of the polymers were adjusted by the modification of chemical structures. The quenching effect of cyano group and oxygen atom results in the lower fluorescence quantum efficiency. The fitted emission spectra suggested that the emission spectra of all the polymers come from different vibronic transitions and aggregation emission. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
123.
Bakhat Ali Muhammad Khalid Sumreen Asim Muhammad Usman Khan Zahid Iqbal Ajaz Hussain Riaz Hussain Sarfraz Ahmed Akbar Ali Amjad Hussain Muhammad Imran Mohammed A. Assiri Muhammad Fayyaz ur Rehman Chenxi Wang Changrui Lu 《Molecules (Basel, Switzerland)》2021,26(9)
Organic materials development, especially in terms of nonlinear optical (NLO) performance, has become progressively more significant owing to their rising and promising applications in potential photonic devices. Organic moieties such as carbazole and quinoline play a vital role in charge transfer applications in optoelectronics. This study reports and characterizes the donor–acceptor–donor–π–acceptor (D–A–D–π–A) configured novel designed compounds, namely, Q3D1–Q3D3, Q4D1–Q1D2, and Q5D1. We further analyze the structure–property relationship between the quinoline–carbazole compounds for which density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were performed at the B3LYP/6-311G(d,p) level to obtain the optimized geometries, natural bonding orbital (NBO), NLO analysis, electronic properties, and absorption spectra of all mentioned compounds. The computed values of λmax, 364, 360, and 361 nm for Q3, Q4, and Q5 show good agreement of their experimental values: 349, 347, and 323 nm, respectively. The designed compounds (Q3D1–Q5D1) exhibited a smaller energy gap with a maximum redshift than the reference molecules (Q3–Q5), which govern their promising NLO behavior. The NBO evaluation revealed that the extended hyperconjugation stabilizes these systems and caused a promising NLO response. The dipole polarizabilities and hyperpolarizability (β) values of Q3D1–Q3D3, Q4D1-Q1D2, and Q5D1 exceed those of the reference Q3, Q4, and Q5 molecules. These data suggest that the NLO active compounds, Q3D1–Q3D3, Q4D1–Q1D2, and Q5D1, may find their place in future hi-tech optical devices. 相似文献
124.
125.
合成出了一系列新型基于咔唑的单-/双-碳酰腙衍生物3和4.利用1H NMR、13C NMR、IR和元素分析对其进行了结构表征.评价了目标化合物对蛋白酪氨酸磷酸酶1B(PTP1B)的抑制活性,讨论了结构与活性的关系.实验结果显示,大部分化合物对PTP1B具有良好的抑制活性,其中1,5-双[(9-丁基-3-咔唑基)亚甲基]碳酰腙(4c)的抑制活性最高,IC50=(4.81±0.41)mmol/L,且活性高于对照药物齐墩果酸.对目标化合物1-[(9-庚基-3-咔唑基)亚甲基]碳酰腙(3f)和4c进行分子对接研究和密度泛函理论(DFT)计算.分子对接结果表明,化合物3f和4c结合到PTP1B酶由螺旋α3和α6形成的活性位点,与PTP1B酶通过氢键、极性、疏水和p-p等相互作用形成了稳定的复合物. 相似文献
126.
合成了一系列新型的基于咔唑的单-/双-硫代碳酰腙衍生物.利用IR、1H NMR、13C NMR和元素分析对其进行了结构表征.评价了目标化合物对Cdc25B和PTP1B的抑制活性,讨论了其结构与活性的关系.实验结果显示,大部分目标化合物对Cdc25B和PTP1B表现出良好的抑制活性.其中,1,5-双[(9-戊基-3-咔唑基)亚甲基]硫代碳酰腙(4d)对Cdc25B的抑制活性最高,IC50为(0.23±0.02)μg/m L.1,5-双[(9-乙基-3-咔唑基)亚甲基]硫代碳酰腙(4a)对PTP1B的抑制活性最高, IC50为(1.00±0.16)μg/m L.对目标化合物4a和4d进行分子对接研究和密度泛函理论(DFT)计算,结果表明,目标化合物4d和4a分别进入到了Cdc25B和PTP1B酶的活性位点区域,有活性作用的主要是硫代碳酰腙和咔唑基团. 相似文献
127.
ZHAO Qian QIU Dong-Fang GUO Ying-Chen FENG Yu-Quan ZHOU Chong-Wang LIU Dong-Mei 《结构化学》2011,30(3):417-423
A novel Ru(Ⅱ) complex [(bpy)2Ru(PBC)](PF6)2 (PBC = N-[4-(9-carbazole)butyl]-2-(2-pyridyl)benzimidazole) has been synthesized and verified by 1H NMR, elemental analysis and X-ray crystallography. The crystal (C48H40F12N8P2Ru, Mr = 1119.89) belongs to the triclinic system, space group P1, with a = 13.128(4), b = 13.814(4), c = 14.184(4) , α = 84.112(6), β = 88.473(6), γ = 78.196(6)°, Z = 2, V = 2504.6(13) 3, Dc = 1.485 g/cm3, F(000) = 1132, R = 0.0750 and wR = 0.1896. The Ru atom adopts a distorted-octahedral coordination geometry with the bond distances and bond angles falling in normal ranges. The complex shows an intense metal-to-ligand charge transfer (1MLCT) (dπ(Ru) →π*(L)) transition (ε ~1.2×104 dm3mol-1cm-1) at 457 nm in the UV-Vis absorption spectrum and a strong red phosphorescence at 632 nm in the CH3CN solution at ambient temperature. An efficient intramolecular energy transfer process from the carbazole unit to the [(bpy)2Ru(PB)]2+ emissive center exists by selective optical-simulation. Its electrochemical behavior shows multiplicate redox processes based on the metal center, the grafting carbazole moiety and the 2-(2-pyridyl)benzimidazole unit. 相似文献
128.
9,9-二-(3-(9-苯咔唑基))-2,7-芘基芴的光电性质 总被引:1,自引:0,他引:1
芴类化合物作为有机电致发光材料近年来引起了人们的广泛关注, 其具有高亮度和高工作效率等性能. 本论文采用量子化学方法研究了一种新型的芴类发光材料, 9,9-二-(3-(9-苯咔唑基))-2,7-芘基芴的光电性质. 具体研究内容包括基态和激发态几何结构、前线分子轨道、能隙、电离能、电子亲和势、重组能以及吸收光谱和发射光谱等. 理论计算结果表明, 9,9-二-(3-(9-苯咔唑基))-2,7-芘基芴发射光谱为450.6 nm, 其在电致发光器件应用上是一种具有开发前景和实用价值的蓝光发光材料. 相似文献
129.
Radhakrishnan Sureshbabu 《Tetrahedron》2009,65(18):3582-1421
Interaction of 2/(3)-methyl-3/(2)-vinylindoles and DMF·DMA/DMA·DMA at 110 °C led to the in situ generation of enamines, which on concurrent electrocyclization followed by subsequent aromatization afforded substituted carbazoles. 相似文献
130.
Cheuk‐Lam Ho Qi Wang Ching‐Shan Lam Wai‐Yeung Wong Dongge Ma Lixiang Wang Zhi‐Qiang Gao Chin‐Hsin Chen Kok‐Wai Cheah Zhenyang Lin 《化学:亚洲杂志》2009,4(1):89-103
The synthesis, isomeric studies, and photophysical characterization of a series of multifunctional cyclometalated iridium(III) complexes containing a fluoro‐ or methyl‐substituted 2‐[3‐(N‐phenylcarbazolyl)]pyridine molecular framework are presented. All of the complexes are thermally stable solids and highly efficient electrophosphors. The optical, electrochemical, photo‐, and electrophosphorescence traits of these iridium phosphors have been studied in terms of the electronic nature and coordinating site of the aryl or pyridyl ring substituents. The correlation between the functional properties of these phosphors and the results of density functional theory calculations was made. Arising from the propensity of the electron‐rich carbazolyl group to facilitate hole injection/transport, the presence of such a moiety can increase the highest‐occupied molecular orbital levels and improve the charge balance in the resulting complexes relative to the parent phosphor with 2‐phenylpyridine ligands. Remarkably, the excited‐state properties can be manipulated through ligand and substituent effects that allow the tuning of phosphorescence energies from bluish green to deep red. Electrophosphorescent organic light‐emitting diodes (OLEDs) with outstanding device performance can be fabricated based on these materials, which show a maximum current efficiency of approximately 43.4 cd A?1, corresponding to an external quantum efficiency of approximately 12.9 % ph/el (photons per electron) and a power efficiency of approximately 33.4 Lm W?1 for the best device. The present work provides a new avenue for the rational design of multifunctional iridium–carbazolyl electrophosphors, by synthetically tailoring the carbazolyl pyridine ring that can reveal a superior device performance coupled with good color‐tuning versatility, suitable for multicolor‐display technology. 相似文献