全文获取类型
收费全文 | 83475篇 |
免费 | 16899篇 |
国内免费 | 6981篇 |
专业分类
化学 | 72910篇 |
晶体学 | 786篇 |
力学 | 3670篇 |
综合类 | 469篇 |
数学 | 8340篇 |
物理学 | 21180篇 |
出版年
2024年 | 202篇 |
2023年 | 1060篇 |
2022年 | 1622篇 |
2021年 | 1822篇 |
2020年 | 3096篇 |
2019年 | 4239篇 |
2018年 | 2615篇 |
2017年 | 2159篇 |
2016年 | 5418篇 |
2015年 | 5583篇 |
2014年 | 5885篇 |
2013年 | 7437篇 |
2012年 | 7186篇 |
2011年 | 6525篇 |
2010年 | 5648篇 |
2009年 | 5475篇 |
2008年 | 5252篇 |
2007年 | 4464篇 |
2006年 | 3916篇 |
2005年 | 3696篇 |
2004年 | 3068篇 |
2003年 | 2706篇 |
2002年 | 3495篇 |
2001年 | 2511篇 |
2000年 | 2311篇 |
1999年 | 1559篇 |
1998年 | 1053篇 |
1997年 | 970篇 |
1996年 | 1022篇 |
1995年 | 829篇 |
1994年 | 742篇 |
1993年 | 578篇 |
1992年 | 567篇 |
1991年 | 516篇 |
1990年 | 403篇 |
1989年 | 312篇 |
1988年 | 227篇 |
1987年 | 198篇 |
1986年 | 211篇 |
1985年 | 181篇 |
1984年 | 128篇 |
1983年 | 93篇 |
1982年 | 61篇 |
1981年 | 49篇 |
1980年 | 23篇 |
1979年 | 22篇 |
1977年 | 25篇 |
1976年 | 21篇 |
1975年 | 32篇 |
1974年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
近年来,基于透射电子显微技术、微纳加工技术和薄膜制造技术的发展,原位液相透射电子显微技术产生,为构建多种纳米级分辨率尺度下的微实验平台,发展新型纳米表征技术和众多领域的相关研究提供了途径.本文首先介绍了应用于原位液相透射电子显微技术的液体腔设计要求,然后介绍了液体腔的发展和典型的制备工艺,最后综述了近年来液体腔透射电子显微镜在纳米粒子成核和生长方面的应用研究,并探讨了该技术前沿发展面临的机遇和挑战.本文将为提高我国先进纳米表征技术和原子精准构筑技术提供相关讨论和支持. 相似文献
92.
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
93.
94.
Dong Zheng Fu-Quan Wang Yuan-Guang Li Liang-Hong Guo Jing Cheng 《Analytica chimica acta》2004,508(2):225-231
Optimized combination of chemical agents was selected for sensitive electrochemical detection of dissolved ruthenium tris-(2,2′-bipyridine) (Ru-bipy). The detection was based on the chemical amplification mechanism, in which the anodic current of a redox-active analyte was amplified by a sacrificial electron donor in solution. On indium-doped tin oxide (ITO) electrodes, electrochemical reaction of the analyte was reversible, but that of the electron donor was greatly suppressed. Several transition metal complexes, such as ferrocene and tris-(2,2′-bipyridine) complexes of osmium, iron and ruthenium, were evaluated as model analyte. A correlation between the amplified current and the standard potential of the complex was observed, and Ru-bipy generated the largest current. A variety of organic bases, acids and zwitterions were assessed as potential electron donor. Sodium oxalate was found to produce the largest amplification factor. With Ru-bipy as the model analyte and oxalate as the electron donor, the analyte concentration curve was linear up to 50 μM, with a lower detection limit of approximately 50 nM. Preliminary work was presented in which a Ru-bipy derivative was attached to bovine serum albumin and detected electrochemically. Although the combination of Ru-bipy, oxalate and ITO electrode has been used before for electrochemiluminescent detection of Ru-bipy and oxalate, as well as electrochemical detection of oxalate, its utility in amplified voltammetric detection of Ru-bipy as a potential electrochemical label has not been reported previously. 相似文献
95.
96.
97.
98.
We prove the existence of global smooth solutions near a given steady state of the hydrodynamic model of the semiconductors
in a bounded domain with physical boundary conditions. The steady state and the doping profile are permitted to be of large
variation but the initial velocity must be small. Two cases are considered. In the first one the problem is three-dimensional,
the boundary conditions are insulating and the steady state velocity vanishes. In the second one, the problem is one-dimensional,
the boundary is of contact type and the steady state velocity does not vanish. 相似文献
99.
100.
超临界流体色谱流程设计及其应用 总被引:1,自引:1,他引:0
本文设计了多功能超临界流体色谱流程,流程中包括毛细管/微填充柱SFC,GC,计算机控制温度、压力、密度及信号采集、处理,配置有超临界流体萃取池,解决了超临界流体色谱分流口易堵问题。利用该流程,将石腊、DC-200气相色谱固定相、黄油、蜂蜡、救心油、红花油等样品进行超临界流体色谱分离。 相似文献