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   175995篇
  免费   574篇
  国内免费   134篇
化学   73331篇
晶体学   2452篇
力学   10414篇
综合类   1篇
数学   32443篇
物理学   58062篇
  2021年   867篇
  2020年   965篇
  2019年   1105篇
  2018年   10330篇
  2017年   11199篇
  2016年   6183篇
  2015年   1851篇
  2014年   1844篇
  2013年   3395篇
  2012年   7264篇
  2011年   15920篇
  2010年   9752篇
  2009年   9888篇
  2008年   13734篇
  2007年   17311篇
  2006年   2966篇
  2005年   9164篇
  2004年   5682篇
  2003年   5619篇
  2002年   3608篇
  2001年   2402篇
  2000年   1960篇
  1999年   1293篇
  1998年   1172篇
  1997年   1042篇
  1996年   1038篇
  1995年   924篇
  1994年   894篇
  1993年   885篇
  1992年   919篇
  1991年   1000篇
  1990年   938篇
  1989年   968篇
  1988年   891篇
  1987年   856篇
  1986年   804篇
  1985年   948篇
  1984年   1058篇
  1983年   900篇
  1982年   918篇
  1981年   833篇
  1980年   782篇
  1979年   867篇
  1978年   997篇
  1977年   936篇
  1976年   868篇
  1975年   815篇
  1974年   830篇
  1973年   847篇
  1972年   591篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
31.
32.
Russian Journal of General Chemistry - The main sources of emissions of industrial nitrogen oxides have been reviewed. A promising method for the absorption of nitrogen monoxide by a reusable...  相似文献   
33.
The results of investigation of optical image detectors designed for the largest problem, near-VUV, range of the spectrum are presented. The possibility of using a dual-stage image detection system to appreciably lower the sensitivity threshold and make computer data processing feasible is considered. The integration of a UV module into a wideband image detector is studied.  相似文献   
34.
Russian Chemical Bulletin - Quantum chemical calculations and a comparative analysis of Raman spectra of 3,4,5-triphenyl-1-propyl-1,2-diphosphole (1),...  相似文献   
35.
36.
Two new compounds of fluorine: (C2H5)4N[I2F] and (C2H5)4N[Br2F], have been easily synthesized in a nearly quantitative by a direct reaction of (C2H5)4NF, I2 and Br2. The products were isolated and characterized by elemental analysis and spectroscopic methods such as: Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). These compounds have been studied computationally with the Scalar ZORA relativistic level of theory using the ADF program package. The molecular parameters, and vibrational spectra were calculated. The excitation energies were found by timedependent perturbation density functional theory (TD-DFT). Molecule optimization, frequencies and excitation energies were calculated with standard Slatertype-orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all atoms. The FTIR, UV-Vis spectra and assignment of principal transitions and total density of state (TDOS) were extracted using the GaussSum 2.2 program. The comparison between experimental and calculated values showes that the experimental results correlate well with the predicted data.  相似文献   
37.
Development of biocompatible porous supports is a promising strategy in the field of tissue engineering for the repair and regeneration of bone tissues with severe damage. Graphene oxide aerogels (GOAs) are excellent candidates for the manufacture of these systems due to their porosity, ability to imitate bone structure, and mechanical resistance, and according to their surface chemical reactivity, they can facilitate osseointegration, osteogenesis, osteoinduction and osteoconduction. In this review, synthesis of GOAs from the most primary source is described, and recent studies on the use of these functionalized carbonaceous foams as scaffolding for bone tissue regeneration are presented.  相似文献   
38.
Transport in Porous Media - In the original publication of the article, Table 2 was published incorrectly.  相似文献   
39.
Journal of Experimental and Theoretical Physics - We suggest that the principle of holographic duality be extended beyond conformal invariance and AdS isometry. Such an extension is based on a...  相似文献   
40.
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