全文获取类型
收费全文 | 12455篇 |
免费 | 2162篇 |
国内免费 | 1826篇 |
专业分类
化学 | 9213篇 |
晶体学 | 224篇 |
力学 | 774篇 |
综合类 | 125篇 |
数学 | 1291篇 |
物理学 | 4816篇 |
出版年
2024年 | 21篇 |
2023年 | 216篇 |
2022年 | 378篇 |
2021年 | 482篇 |
2020年 | 530篇 |
2019年 | 464篇 |
2018年 | 447篇 |
2017年 | 416篇 |
2016年 | 595篇 |
2015年 | 644篇 |
2014年 | 826篇 |
2013年 | 964篇 |
2012年 | 1040篇 |
2011年 | 1163篇 |
2010年 | 862篇 |
2009年 | 813篇 |
2008年 | 943篇 |
2007年 | 880篇 |
2006年 | 784篇 |
2005年 | 634篇 |
2004年 | 506篇 |
2003年 | 417篇 |
2002年 | 389篇 |
2001年 | 351篇 |
2000年 | 257篇 |
1999年 | 242篇 |
1998年 | 182篇 |
1997年 | 171篇 |
1996年 | 169篇 |
1995年 | 133篇 |
1994年 | 86篇 |
1993年 | 73篇 |
1992年 | 59篇 |
1991年 | 56篇 |
1990年 | 45篇 |
1989年 | 29篇 |
1988年 | 29篇 |
1987年 | 31篇 |
1986年 | 22篇 |
1985年 | 20篇 |
1984年 | 19篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1971年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Jin Xie Yun-Wei Song Dr. Bo-Quan Li Dr. Hong-Jie Peng Prof. Jia-Qi Huang Prof. Qiang Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22334-22339
Polysulfide intermediates (PSs), the liquid-phase species of active materials in lithium–sulfur (Li-S) batteries, connect the electrochemical reactions between insulative solid sulfur and lithium sulfide and are key to full exertion of the high-energy-density Li-S system. Herein, the concept of sulfur container additives is proposed for the direct modification on the PSs species. By reversible storage and release of the sulfur species, the container molecule converts small PSs into large organosulfur species. The prototype di(tri)sulfide-polyethylene glycol sulfur container is highly efficient in the reversible PS transformation to multiply affect electrochemical behaviors of sulfur cathodes in terms of liquid-species clustering, reaction kinetics, and solid deposition. The stability and capacity of Li-S cells was thereby enhanced. The sulfur container is a strategy to directly modify PSs, enlightening the precise regulation on Li-S batteries and multi-phase electrochemical systems. 相似文献
12.
Double Michael additions of lithium enolaie of 1,4-dioxaspiro[4.5]dec-6-en-8-one to four acrylates afforded bicyclo[2.2.2]octan-2-ones with high regio- and stereoselectivities in moderate yields. 相似文献
13.
14.
15.
16.
Fiber-optic reflex sensor for in-line production measurement 总被引:1,自引:0,他引:1
The paper describes experiments concerning distance measurement with fiber-optic sensor and improvement of the measurement principle. The sensor probe was well-designed with a small structure and multi-function. The novel optical fiber probe arrangement as well as the possibilities of use for complex measurement problems are explained using the measurement of an internal screw thread as an example. The experimental results show that the measurement uncertainty of the thread minor diameter can reach ±10 μm, and the stability of the measurement system is better than 0.07%. 相似文献
17.
18.
By using the quasi-Lyapunov function, some sufficient conditions of global exponential stability for impulsive systems are established, which is the basis for the following discussion. Then, by employing Riccati inequality and Hamilton-Jacobi inequality approach, some sufficient conditions of robust exponential stability for uncertain linear/nonlinear impulsive systems are derived, respectively. Finally, some examples are given to illustrate the applications of the theory. 相似文献
19.
采用溶解-反应量热法在具有恒温环境的溶解-反应热量计内,测定了[Gd(Gly)4(Im)(H2O)](ClO4)3和[Y(Gly)4(Im)(H2O)](ClO4)3两种稀土甘氨酸咪唑配合物的标准生成焓分别为(-3 461.46 ±0.22) kJ·mol-1 和(-3 926.6±0.90) kJ·mol-1. 相似文献
20.
Wang Qing-Lun Zhao Bin Liao Dai-Zheng Yan Shi-Ping Cheng Peng Jiang Zong-Hui 《Transition Metal Chemistry》2003,28(3):326-330
The copper(II) complex Na2[Cu(pba)] · 6H2O has been synthesized and its structure determined. It consists of a novel two-dimensional network of [Cu(pba)]2– anions connected to each other through the sodium ion as a bridge. Spectroscopic and magnetic properties have been measured and a spin distribution calculation has been carried out with the GAUSSIAN-94. Theoretical calculations indicate the rather larger spin density on nitrogen atoms should be responsible for the satellite lines appearing beside the main hyperfine coupling signs of copper(II). The antiferromagnetic interaction may be due to the intermolecular interaction and/or different copper(II) ions through the Na+ bridge in the same layer. 相似文献