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   1320篇
  免费   21篇
  国内免费   9篇
化学   899篇
晶体学   17篇
力学   38篇
数学   104篇
物理学   292篇
  2023年   4篇
  2022年   6篇
  2021年   8篇
  2020年   11篇
  2019年   12篇
  2018年   9篇
  2016年   19篇
  2015年   20篇
  2014年   21篇
  2013年   54篇
  2012年   51篇
  2011年   56篇
  2010年   32篇
  2009年   42篇
  2008年   52篇
  2007年   68篇
  2006年   57篇
  2005年   77篇
  2004年   63篇
  2003年   61篇
  2002年   70篇
  2001年   47篇
  2000年   33篇
  1999年   20篇
  1998年   12篇
  1997年   12篇
  1996年   23篇
  1995年   12篇
  1994年   16篇
  1993年   22篇
  1992年   17篇
  1991年   21篇
  1990年   15篇
  1989年   16篇
  1988年   21篇
  1987年   16篇
  1986年   10篇
  1985年   23篇
  1984年   22篇
  1983年   20篇
  1982年   15篇
  1981年   17篇
  1980年   11篇
  1979年   15篇
  1978年   16篇
  1977年   21篇
  1976年   14篇
  1975年   12篇
  1974年   16篇
  1973年   10篇
排序方式: 共有1350条查询结果,搜索用时 218 毫秒
111.
112.
113.
A high-temperature perturbation theory for the transfer-integral equation of a sine-Gordon system is presented where an approximate solution is obtained to an order of the modified Bessel Functions In(U2kBT). The specific heat and the static structure factor are discussed in the first-order approximation.  相似文献   
114.
FeK absorption spectra of FeCl3-doped polyacetylene [CH(FeCl3)y]x having y values of 0.024, 0.087 and 0.13, were measured by use of synchrotron radiation. The analyses of observed EXAFS data showed that Fe atom is surrounded by about four Cl atoms with Fe-Cl distance of 2.18–2.20 Å. It is concluded that the dopant exists mainly in the form of FeCl4-, and the following reaction takes place in the FeCl3 doping process. 2FeCl3 + e- → FeCl4- + FeCl2  相似文献   
115.
To examine wall effects, the steady state settling velocities of single solid spheres of various diameters were measured in triangular and square cylinders, and between parallel plates, which were filled up with highly viscous aqueous milet jelley solutions. The wall effect for the steady state motion of single spheres in a narrow space has to date been correlated by the wall correction factor. The wall correction factors of single solid spheres were correlated in such apparatus in the creeping flow region.  相似文献   
116.
Three convenient procedures are described for applying anion exchange resins to the preconcentration and irradiation support in neutron activation analysis. For each procedure the amounts of interferences were determined. The effect of the form, cross-linkage, pore size, and particle size of the resins on the elimination of interferences was investigated. Some other associated problems are also presented, viz. effect of concentration and temperature of washing solution, effect of irradiation time, and comparison with filter  相似文献   
117.
Ishii H  Satoh K  Satoh Y  Koh H 《Talanta》1982,29(7):545-550
alpha,beta,gamma,delta-Tetrakis(1-methylpyridinium-3-yl)porphine [T(3-MPy)P] and alpha,beta,gamma,delta-tetrakis(1-methylpyridinium-4-yl)porphine [T(4-MPy)P] have been found to react rapidly with cadmium to give coloured complexes in weakly alkaline media at room temperature. Simple and practical methods for the determination of cadmium at ng/ml levels by conventional and analogue derivative spectrophotometry have been proposed. The analogue method gives higher sensitivity. T(3-MPy)P gives higher sensitivity than T(4-MPy)P. The interference of various foreign cations and anions has also been examined and in many cases eliminated or reduced. Adsorption of the porphyrins and their cadmium complexes onto the glassware, which is usually observed under the conditions of reaction and causes significant errors in the determination, can be suppressed almost completely by addition of fairly large amounts of a salt such as sodium chloride.  相似文献   
118.
We developed a high radiation sensitive polymer gel by modifying the amounts of the gel components and the temperature for the gel preparation. We evaluated its relaxation time linearity against dose and compared the measured dose distribution with the calculated one. For the relaxation time-dose linearity, irradiations were carried out with a linear accelerator using 6 MV photons and doses ranging from 0-5.0 Gy. The relationship between dose and R(2) value (reciprocal of T(2) relaxation time) was measured and it had good linearity over a wide range (0.3-5 Gy). The measured dose distributions were in good agreement with calculated ones. Since the present gel has higher sensitivity and it is synthesized more easily at lower cost than conventional polymer gels, we expect to see improved three-dimensional (3D) dosimetry using it.  相似文献   
119.
Vortexlike turbulent structures in hot-ion mode plasmas with several keV are observed in the case with a radially produced weak shear of electric fields E(r). However, a strong E(r) shear formation due to a high ion-confining potential phi(c) production clears up these vortices together with plasma-confinement improvement and disappearance of both drift-wave and turbulencelike Fourier spectral signals. These findings are based on three-time progress in phi(c) in comparison to phi(c) attained 1992-2002. The significant advance of phi(c) is well extended in line with proposed potential-formation physics scalings.  相似文献   
120.
We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).  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