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   178264篇
  免费   576篇
  国内免费   136篇
化学   74717篇
晶体学   2674篇
力学   10479篇
综合类   2篇
数学   32643篇
物理学   58461篇
  2022年   650篇
  2021年   897篇
  2020年   998篇
  2019年   1144篇
  2018年   10351篇
  2017年   11210篇
  2016年   6233篇
  2015年   1880篇
  2014年   1913篇
  2013年   3472篇
  2012年   7314篇
  2011年   15955篇
  2010年   9793篇
  2009年   9927篇
  2008年   13773篇
  2007年   17339篇
  2006年   3034篇
  2005年   9176篇
  2004年   5722篇
  2003年   5668篇
  2002年   3661篇
  2001年   2440篇
  2000年   1993篇
  1999年   1330篇
  1998年   1199篇
  1997年   1087篇
  1996年   1099篇
  1995年   966篇
  1994年   930篇
  1993年   922篇
  1992年   959篇
  1991年   1032篇
  1990年   982篇
  1989年   1018篇
  1988年   936篇
  1987年   880篇
  1986年   857篇
  1985年   981篇
  1984年   1104篇
  1983年   951篇
  1982年   954篇
  1981年   859篇
  1980年   821篇
  1979年   914篇
  1978年   1029篇
  1977年   968篇
  1976年   909篇
  1975年   861篇
  1974年   864篇
  1973年   883篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Physics of Particles and Nuclei Letters - When creating accelerators and storage-ring installations in a compact space, there is not always enough space for all the necessary magnet elements. In...  相似文献   
2.
3.
4.
5.
6.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant.  相似文献   
7.
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   
8.
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   
9.
10.
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   
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