全文获取类型
收费全文 | 8883篇 |
免费 | 1387篇 |
国内免费 | 1089篇 |
专业分类
化学 | 6347篇 |
晶体学 | 84篇 |
力学 | 406篇 |
综合类 | 102篇 |
数学 | 1025篇 |
物理学 | 3395篇 |
出版年
2024年 | 3篇 |
2023年 | 194篇 |
2022年 | 193篇 |
2021年 | 274篇 |
2020年 | 386篇 |
2019年 | 377篇 |
2018年 | 304篇 |
2017年 | 302篇 |
2016年 | 421篇 |
2015年 | 417篇 |
2014年 | 516篇 |
2013年 | 619篇 |
2012年 | 819篇 |
2011年 | 799篇 |
2010年 | 529篇 |
2009年 | 481篇 |
2008年 | 607篇 |
2007年 | 586篇 |
2006年 | 479篇 |
2005年 | 434篇 |
2004年 | 296篇 |
2003年 | 242篇 |
2002年 | 219篇 |
2001年 | 207篇 |
2000年 | 213篇 |
1999年 | 177篇 |
1998年 | 170篇 |
1997年 | 139篇 |
1996年 | 155篇 |
1995年 | 143篇 |
1994年 | 108篇 |
1993年 | 98篇 |
1992年 | 80篇 |
1991年 | 61篇 |
1990年 | 63篇 |
1989年 | 40篇 |
1988年 | 37篇 |
1987年 | 32篇 |
1986年 | 25篇 |
1985年 | 34篇 |
1984年 | 15篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1962年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.
Dr. Xiao‐Ye Wang Dr. Jie‐Yu Wang Prof. Jian Pei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3528-3539
Replacement of C?C unit with its isoelectronic B?N unit in aromatics provides a new class of molecules with appealing properties, which have attracted great attention recently. In this Concept, we focus on BN‐substituted polycyclic aromatics with fused structures, and review their synthesis, photophysical, and redox properties, as well as their applications in organic electronics. We also present challenging synthetic targets, large BN‐ substituted polycyclic aromatics, such as regioregular BN heterosuperbenzenes, which can be viewed as BN‐doped nanographenes. Finally, we propose an atomically precise bottom‐up synthesis of structurally well‐defined BN‐doped graphenes. 相似文献
22.
Gold‐Catalyzed Tandem Cycloisomerization–Halogenation of Chiral Homopropargyl Sulfonamides 下载免费PDF全文
Chao Shu Long Li Cang‐Hai Shen Peng‐Peng Ruan Chao‐Yue Liu Prof. Dr. Long‐Wu Ye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2282-2290
Two new gold‐catalyzed tandem cycloisomerization–halogenation reactions of chiral homopropargyl sulfonamides have been developed. Various enantioenriched 3,3‐diiodopyrrolidin‐2‐ols and 3‐fluoropyrrolidin‐2‐ols were obtained in moderate‐to‐good yields with excellent enantio‐ and diastereoselectivity. 相似文献
23.
24.
Inside Cover: Selective Transformation of Syngas into Gasoline‐Range Hydrocarbons over Mesoporous H‐ZSM‐5‐Supported Cobalt Nanoparticles (Chem. Eur. J. 5/2015) 下载免费PDF全文
25.
Low band‐gap diketopyrrolopyrrole‐containing polymers for near infrared electrochromic and photovoltaic applications 下载免费PDF全文
Jonathan Zhaozhi Low Wei Teng Neo Qun Ye Wen Jie Ong Ivy Hoi Ka Wong Ting Ting Lin Jianwei Xu 《Journal of polymer science. Part A, Polymer chemistry》2015,53(10):1287-1295
Donor–acceptor type polymers bearing diketopyrrolopyrrole and 3,4‐ethylenedioxythiophene units are reported. The polymers are green and exhibit very low band‐gaps (1.19 eV) with strong and broad absorption (maxima of about 830 nm) in the near infrared (NIR) region in their neutral film states. The polymers display color changes between dark green and light blue with exceptional optical contrasts in the NIR regions of up to 78 and 63% as thin films and single‐layer electrochromic devices, respectively. Fast switching, good stabilities as well as high coloration efficiencies (743–901 cm2 C?1) were also observed. The polymers could also be potentially used as photovoltaic material, with a power conversion efficiency of up to 1.68%. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1287–1295 相似文献
26.
27.
Synthesis of polymer with defined fluorescent end groups via reversible addition fragmentation transfer polymerization for characterizing the conformations of polymer chains in solutions 下载免费PDF全文
Ye Sha Qing Zhu Yuanxin Wan Linling Li Xiaoliang Wang Gi Xue Dongshan Zhou 《Journal of polymer science. Part A, Polymer chemistry》2016,54(15):2413-2420
A new type of chain transfer agent used in reversible addition fragmentation chain transfer (RAFT) polymerization named 9‐anthracenylmethyl (4‐cyano‐4‐(N‐carbazylcarbodithioate) pentanoate) (ACCP) was synthesized with a total yield over 75% by the incorporation of both fluorescent donor and acceptor chromophores. Polymerization of heterotelechelic α,ω end‐labeled dye‐functionalized polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(n‐butyl methacrylate) (PBMA) with adjustable molecular weights and narrow polydispersity could be conducted by a one‐pot procedure through RAFT polymerization with this bischromophore chain transfer agent. The polymerizations demonstrated “living” controlled characteristics. By taking advantage of the characteristic fluorescence resonance energy transfer (FRET) response between the polymer chain terminals, the variation of chain dimensions in solution from the dilute region to the semidilute region can be monitored by changes in the ratio of the fluorescence intensities of the carbazolyl group to the anthryl group, which lends itself to potential applications in characterizing chain dimensions in solutions for thermodynamic or dynamic studies. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2413–2420 相似文献
28.
29.
LC‐MS/MS analysis of Gegen Qinlian Decoction and its pharmacokinetics after oral administration to rats 下载免费PDF全文
Yifan Zhang Jin Yuan Yizhu Zhang Ye Chen Jiaoxian Cao Rui An Xinhong Wang 《Biomedical chromatography : BMC》2015,29(4):485-495
A liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method was developed and validated for the simultaneous determination of 12 constituents of Gegen Qinlian Decoction (GQD), namely puerarin, daidzein, baicalin, wogonoside, wogonin, liquiritin, liquiritigenin, berberine, jatrorrhizine, palmatine, coptisine and glycyrrhetic acid, in rat plasma. The plasma samples were spiked with the internal standard (IS) carbamazepine acidified with HCl and extracted by liquid–liquid extraction with ethyl acetate. Chromatographic separation was achieved on a Shiseido Capcell PAK C18 column utilizing a gradient elution profile and a mobile phase consisting of (A) 0.1% formic acid in water and (B) acetonitrile. Detection was performed in the multiple reaction monitoring mode using electrospray ionization in the positive ion mode at a flow rate of 0.3 mL/min and a run time of 8 min. All of the calibration curves gave good linearity (r > 0.9930) over the concentration range from 0.6–360 to 16.2–9720 ng/mL for all components. The intra‐ and inter‐day precisions were <15.0% in terms of the relative standard deviation, and the accuracies were within ±13.7% in terms of the relative error. The method was successfully applied to investigate the pharmacokinetics of the major active compounds of Gegen Qinlian Decoction after its oral administration to rats. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
30.