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   218971篇
  免费   2996篇
  国内免费   603篇
化学   104736篇
晶体学   3142篇
力学   7590篇
综合类   3篇
数学   22914篇
物理学   60160篇
无线电   24025篇
  2021年   1971篇
  2020年   1994篇
  2019年   2126篇
  2018年   2567篇
  2017年   2607篇
  2016年   4177篇
  2015年   2739篇
  2014年   4071篇
  2013年   9560篇
  2012年   7448篇
  2011年   8858篇
  2010年   6334篇
  2009年   6508篇
  2008年   8740篇
  2007年   8771篇
  2006年   8293篇
  2005年   7533篇
  2004年   6920篇
  2003年   6278篇
  2002年   6085篇
  2001年   6528篇
  2000年   5103篇
  1999年   4123篇
  1998年   3556篇
  1997年   3394篇
  1996年   3260篇
  1995年   3061篇
  1994年   2956篇
  1993年   2907篇
  1992年   3158篇
  1991年   3063篇
  1990年   2921篇
  1989年   2807篇
  1988年   2757篇
  1987年   2518篇
  1986年   2381篇
  1985年   3056篇
  1984年   3144篇
  1983年   2754篇
  1982年   2871篇
  1981年   2675篇
  1980年   2635篇
  1979年   2723篇
  1978年   2777篇
  1977年   2673篇
  1976年   2739篇
  1975年   2614篇
  1974年   2545篇
  1973年   2736篇
  1972年   1752篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
Kinetics and Catalysis - The results of studies in the field of synthesis and characterization of layered double hydroxides (LDHs) obtained using solid-phase reactions are summarized. The effect of...  相似文献   
2.
Journal of Structural Chemistry - A new polymorph of the [ReCl3(MeCN)(PPh3)2] complex is synthesized and characterized by single crystal X-ray diffraction (XRD). Its recrystallization from the...  相似文献   
3.
Russian Journal of Applied Chemistry - A method for the disposal of hydrolysis lignin waste based on its modification with ZnCl2 and FeCl3 and subsequent carbonization at 800°C was proposed....  相似文献   
4.
Journal of Applied Spectroscopy - Three simple, sensitive, precise, and rapid spectrophotometric methods are developed and optimized for the assay of vardenafil in pharmaceutical formulations. The...  相似文献   
5.

A kinetic study of the effect of thermoheliox (inhalation of a helium and oxygen mixture, 70 °C) on the functional hemodynamics of the human brain by functional magnetic resonance imaging was carried out. The dynamic responses of the BOLD signal were found to be biphasic. An empirical equation describing the first phase of the hemodynamic response to visual stimulus was proposed. It was shown that preliminary inhalation of thermoheliox stimulates the hemodynamic responses by slowing down the vasoconstriction.

  相似文献   
6.
Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI2. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions.  相似文献   
7.
Mathematical Physics, Analysis and Geometry - In this paper, we develop the dressing method to study the modified Camassa-Holm equation with the help of reciprocal transformation and the associated...  相似文献   
8.
Optics and Spectroscopy - The current–voltage characteristics and photocurrent of “monolithic” diode optical pairs optically coupled by a substrate made of InAs common for them...  相似文献   
9.
10.
Van’kov  A. B.  Kukushkin  I. V. 《JETP Letters》2021,113(2):102-114
JETP Letters - Extraordinary multiparticle effects in quantizing magnetic fields that are manifested in strongly interacting two-dimensional electron systems in MgZnO/ZnO heterostructures have been...  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