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   10271篇
  免费   1542篇
  国内免费   1237篇
化学   7300篇
晶体学   116篇
力学   660篇
综合类   67篇
数学   1288篇
物理学   3619篇
  2024年   17篇
  2023年   251篇
  2022年   251篇
  2021年   338篇
  2020年   427篇
  2019年   444篇
  2018年   380篇
  2017年   362篇
  2016年   506篇
  2015年   502篇
  2014年   576篇
  2013年   782篇
  2012年   867篇
  2011年   939篇
  2010年   652篇
  2009年   588篇
  2008年   724篇
  2007年   603篇
  2006年   549篇
  2005年   411篇
  2004年   368篇
  2003年   273篇
  2002年   290篇
  2001年   206篇
  2000年   195篇
  1999年   253篇
  1998年   175篇
  1997年   131篇
  1996年   136篇
  1995年   132篇
  1994年   99篇
  1993年   107篇
  1992年   87篇
  1991年   86篇
  1990年   77篇
  1989年   58篇
  1988年   41篇
  1987年   36篇
  1986年   22篇
  1985年   31篇
  1984年   20篇
  1983年   14篇
  1982年   12篇
  1981年   5篇
  1980年   4篇
  1979年   3篇
  1978年   5篇
  1976年   3篇
  1975年   3篇
  1957年   3篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
41.
A rigid supramolecular polymer was constructed in aqueous solution via cucurbit[8]uril(CB[8]) host recognition with a rigid monomer containing an azobenzene unit and two 4,4'-bipyridin-1-ium(BP)moieties in the two ends, which also exhibited photo-responsiveness owing to the photoinduced trans–cis isomerization of azobenzene group.  相似文献   
42.
Highly conductive, crystalline, polymer electrolytes, β‐cyclodextrin (β‐CD)–polyethylene oxide (PEO)/LiAsF6 and β‐CD–PEO/NaAsF6, were prepared through supramolecular self‐assembly of PEO, β‐CD, and LiAsF6/NaAsF6. The assembled β‐CDs form nanochannels in which the PEO/X+ (X=Li, Na) complexes are confined. The nanochannels provide a pathway for directional motion of the alkali metal ions and, at the same time, separate the cations and the anions by size exclusion.  相似文献   
43.
44.
Silicone/fluorine‐functionalized polyacrylates were synthesized and subsequently used to prepare corrosion‐resistant transparent coatings via electrophoretic deposition. The coated tin plate with the functionalized polyacrylate had a gloss value higher than 95.0 GU and resisted rust after immersion in a 5 wt% NaCl solution for 10 days. In addition, these coatings remained adhered strongly to the tin plates even after they were bent. It is hoped that this work will provide useful experimental data and assist researchers with the design of applicable coatings with desirable properties. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
45.
In this paper, we study some properties of composition operators on Hilbert spaces of Dirichlet series, which include the Fredholmness, Hilbert-Schmidtness, spectra, cyclic and hypercyclic phenomenons, and also answer a norm question raised by Cowen and MacCluer.  相似文献   
46.
47.
This review is mainly focused on the optoelectronic properties of diamond-based one-dimensional-metal-oxide heterojunction. First, we briefly introduce the research progress on one-dimensional (1D)-metal-oxide heterojunctions and the features of the p-type boron-doped diamond (BDD) film; then, we discuss the use of three oxide types (ZnO, TiO2 and WO3) in diamond-based-1D-metal-oxide heterojunctions, including fabrication, epitaxial growth, photocatalytic properties, electrical transport behavior and negative differential resistance behavior, especially at higher temperatures. Finally, we discuss the challenges and future trends in this research area. The discussed results of about 10 years’ research on high-performance diamond-based heterojunctions will contribute to the further development of photoelectric nano-devices for high-temperature and high-power applications.  相似文献   
48.
49.
Nowadays, hydrogen activation by frustrated Lewis pairs (FLPs) and their applications are one of the emerging research topics in the field of catalysis. Previous studies have shown that the thermodynamics of this reaction is determined by electronic structures of FLPs and solvents. Herein, we investigated systems consisting of typical FLPs and ionic liquids (ILs), which are well known by their large number of types and excellent solvent effects. The density functional theory (DFT) calculations were performed to study the thermodynamics for H2 activation by both inter- and intra-molecular FLPs, as well as the individual components. The results show that the computed overall Gibbs free energies in ILs are more negative than that computed in toluene. Through the thermodynamics partitioning, we find that ILs favor the H−H cleavage elemental step over the elemental steps of proton attachment, hydride attachment and zwitterionic stabilization. Moreover, the results show that these effects are strongly dependent on the type of FLPs, where intra-molecular FLPs are more affected compared to the inter-molecular FLPs.  相似文献   
50.
Clustered regularly interspaced short palindromic repeats (CRISPR) is a promising technology in the biological world. As one of the CRISPR-associated (Cas) proteins, Cas12a is an RNA-guided nuclease in the type V CRISPR-Cas system, which has been a robust tool for gene editing. In addition, due to the discovery of target-binding-induced indiscriminate single-stranded DNase activity of Cas12a, CRISPR-Cas12a also exhibits great promise in biosensing. This minireview not only gives a brief introduction to the mechanism of CRISPR-Cas12a but also highlights the recent developments and applications in biosensing and gene regulation. Finally, future prospects of the CRISPR-Cas12a system are also discussed. We expect this minireview will inspire innovative work on the CRISPR-Cas12a system by making full use of its features and advantages.  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