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   275740篇
  免费   6942篇
  国内免费   5000篇
化学   147008篇
晶体学   3674篇
力学   14711篇
综合类   333篇
数学   32325篇
物理学   89631篇
  2021年   3554篇
  2020年   3974篇
  2019年   4631篇
  2018年   5860篇
  2017年   5739篇
  2016年   7497篇
  2015年   4377篇
  2014年   7107篇
  2013年   12579篇
  2012年   11090篇
  2011年   12477篇
  2010年   9890篇
  2009年   10028篇
  2008年   11230篇
  2007年   10886篇
  2006年   9766篇
  2005年   8628篇
  2004年   8055篇
  2003年   7244篇
  2002年   7355篇
  2001年   7584篇
  2000年   5712篇
  1999年   4417篇
  1998年   3935篇
  1997年   3717篇
  1996年   3377篇
  1995年   3018篇
  1994年   3189篇
  1993年   3053篇
  1992年   3276篇
  1991年   3419篇
  1990年   3356篇
  1989年   3305篇
  1988年   3135篇
  1987年   3115篇
  1986年   2977篇
  1985年   3599篇
  1984年   3673篇
  1983年   3118篇
  1982年   3051篇
  1981年   2936篇
  1980年   2742篇
  1979年   3210篇
  1978年   3188篇
  1977年   3373篇
  1976年   3461篇
  1975年   3164篇
  1974年   3129篇
  1973年   3261篇
  1972年   2577篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
61.
Russian Journal of Physical Chemistry A - Rapidly quenched alloys of aluminum with cobalt and zirconium are investigated using a combination of means of physicochemical analysis to study the...  相似文献   
62.
International Applied Mechanics - The theorems (statements) on the existence of attractor are proved. A generalized Shilnikov theorem is formulated. In the expression for the saddle of a homoclinic...  相似文献   
63.
Metal halide perovskites have demonstrated impressive properties for achieving efficient monochromatic light-emitting diodes. However, the development of white perovskite light-emitting diodes (PeLEDs) remains a big challenge. Here, we demonstrate a single-emissive-layer all-perovskite white PeLED using a mixed halide perovskite film as the emissive layer. The perovskite film consists of separated mixed halide perovskite phases with blue and red emissions, which are beneficial for suppressing halide anion exchange and preventing charge transfer. As a result, the white PeLED shows balanced white light emission with Commission Internationale de L''Eclairage coordinates of (0.33, 0.33). In addition, we find that the achievement of white light emission from mixed halide perovskites strongly depends on effective modulation of the halide salt precursors, especially lead bromide and benzamidine hydrochloride in our case. Our work provides very useful guidelines for realizing single-emissive-layer all-perovskite white PeLEDs based on mixed halide perovskites, which will spur the development of high-performance white PeLEDs.

We demonstrated a single-emissive-layer all-perovskite white light-emitting diode based on a mixed halide perovskite film.  相似文献   
64.

A complex study of a spearhead dated back to IV mill. BC from burial mound no. 1 near Novosvobodnaya village (collection of the State Historical Museum) and, in particular, the material of spearhead superficial crust has been performed. The elemental and phase composition of the metal of spearhead and the superficial crust on its surface have been determined by scanning electron microscopy, jointly with energydispersive X-ray microanalysis and X-ray phase analysis. A comparative analysis of the results of studying the spearhead superficial crust and similar crusts on other artifacts from the mounds near Novosvobodnaya village suggest natural origin of the crust on copper?arsenic artifacts.

  相似文献   
65.
66.
Russian Journal of General Chemistry - Hybrid liquid crystal systems with different ratios of the components have been prepared on the basis of 5,5′-di(heptadecyl)-2,2′-bipyridine...  相似文献   
67.
68.
69.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling.  相似文献   
70.
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