全文获取类型
收费全文 | 8237篇 |
免费 | 1440篇 |
国内免费 | 916篇 |
专业分类
化学 | 4084篇 |
晶体学 | 452篇 |
力学 | 829篇 |
综合类 | 111篇 |
数学 | 1239篇 |
物理学 | 3878篇 |
出版年
2024年 | 10篇 |
2023年 | 62篇 |
2022年 | 185篇 |
2021年 | 218篇 |
2020年 | 215篇 |
2019年 | 182篇 |
2018年 | 170篇 |
2017年 | 246篇 |
2016年 | 284篇 |
2015年 | 291篇 |
2014年 | 488篇 |
2013年 | 638篇 |
2012年 | 494篇 |
2011年 | 557篇 |
2010年 | 505篇 |
2009年 | 593篇 |
2008年 | 551篇 |
2007年 | 572篇 |
2006年 | 487篇 |
2005年 | 502篇 |
2004年 | 483篇 |
2003年 | 380篇 |
2002年 | 310篇 |
2001年 | 277篇 |
2000年 | 241篇 |
1999年 | 230篇 |
1998年 | 192篇 |
1997年 | 205篇 |
1996年 | 176篇 |
1995年 | 134篇 |
1994年 | 98篇 |
1993年 | 98篇 |
1992年 | 107篇 |
1991年 | 69篇 |
1990年 | 44篇 |
1989年 | 44篇 |
1988年 | 41篇 |
1987年 | 41篇 |
1986年 | 28篇 |
1985年 | 15篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 18篇 |
1980年 | 7篇 |
1979年 | 22篇 |
1978年 | 15篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
J. Haslinger T. Kozubek K. Kunisch G. Peichl 《Journal of Mathematical Analysis and Applications》2004,290(2):665-685
This contribution combines a shape optimization approach to free boundary value problems of Bernoulli type with an embedding domain technique. A theoretical framework is developed which allows to prove continuous dependence of the primal and dual variables in the resulting saddle point problems with respect to the domain. This ensures the existence of a solution of a related shape optimization problem in a sufficiently large class of admissible domains. 相似文献
82.
文献[1]引入一类具有广泛应用前景的随机过程-Markov骨架过程。借助Markov骨架过程的方法研究GI/G/1单重休假服务系统队长,及t时刻到达顾客等待时间的瞬时概率分布。 相似文献
83.
M.A. Grado-Caffaro 《Optik》2003,114(5):237-238
Sensitivity of the velocity of a single electron, in the relativistic case, to a perpendicular magnetic field is evaluated by defining a parameter which becomes useful in a number of cases related to dynamical systems. In particular, the ultrarelativistic case is examined. 相似文献
84.
The dynamics of a single electron submitted to a linearly polarized laser field is examined in the non-relativistic case by calculating an upper bound of the position of the electron in the time domain. 相似文献
85.
Image potential resonances on the Sn/Ge(1 1 1) α-phase are investigated by two closely related methods: specular electron reflection and so-called selective electron scattering. Electrons from image resonances are detected on this surface at 120 and 300 K, i.e. below and above the phase transition at about 200 K. The dispersion of the image resonances reveals at these two temperatures equivalent effective electron masses, which are characteristic for this type of electronic surface states. The results of the two methods are consistent according to the similarity of the scattering processes. Changes in the loss peak intensity with the annealing temperature are assigned to the surface quality and are reflected by characteristic photoemission intensities. 相似文献
86.
Armin C. Schneider Christoph Pasel Michael Luckas Klaus Gerhard Schmidt Jan-Dirk Herbell 《Journal of solution chemistry》2004,33(3):257-273
The single ion activity coefficients of hydrogen and chloride ions in aqueous HCl solutions have been estimated at 25°C at concentrations up to 1 mol-kg–1, using potentiometric measurements with ion-selective electrodes and appropriate calibration procedures. Two methods are described for an internal calibration of the electrodes in the extended Debye–Hückel concentration range. The results are compared to the conventional pH calibration with external buffer solutions. Since the latter calibration method does not account for the liquid junction potential E
J which arises at the reference electrode, the resulting activity coefficients are quite different in HCl solutions of higher concentration. These differences between internal and external calibration decrease significantly, when a correction for E
J is introduced into the conventional pH calibration. Hence, in solutions of higher ionic strength the accuracy of the conventional pH electrode calibration using buffer solutions is very limited, when exact H+ activities are required. The consistency of the results indicates that the liquid junction potentials in the examined systems calculated by the Henderson/Bates approximation are of reasonable precision. 相似文献
87.
The dominant decay modes of charged top-pions (π±t ) are tb or ~b. We consider the single production ofcharged top-pions in association with a top quark via e+ e- annihilation and calculate the production cross section of theprocesses e+ e- → t-bπ+ (tb-π-) at the leading order. We find that it can reach 1.2 fb with reasonable parameter values.The charged top-pions may be detected via the channel tbπ± in the future high energy e+ e- colliders. 相似文献
88.
89.
The behavior of zirconium atoms at the W(100) surface associated with oxygen adsorption at different sample temperatures has been studied by Auger electron spectroscopy (AES), ion scattering spectroscopy (ISS), and the relative change of the work function (Δф) measured by the onset of the secondary electron energy distribution. The results have revealed: (i) adsorption of zirconium onto the W(100) surface followed by the elevation of the sample temperature up to 1710 K in an oxygen partial pressure of 2.7 × 10−4 induces complete diffusion of zirconium atoms into the W(100) substrate; (ii) further exposure of oxygen induces co-existence of oxygen and tungsten on the surface at 1710 K, resulting in a work function of 4.37 eV; (iii) keeping the sample temperature at 1710 K, simple evacuation of the system has resulted in surface segregation of zirconium atoms to the surface to form a zirconium atomic layer on the top-most surface, reducing the work function to 2.7 eV. The results have revealed that this specific behavior of zirconium atoms at high temperature assures, with very good reproducibility, the highly stable performance and long service life of Zr---O/W(100)-emitters in practical use, even in a low vacuum of 10−6 Pa. 相似文献
90.
本文研究了无界无限维商品空间上的生产经济均衡的存在性.虽然我们把商品空间看成是Riesz空间,但并没有在它的正锥上作任何内部假设.同时我们的结果也为现代企业或公司从事经济预测、制订生产计划、改善经营管理、提高劳动生产率以及优化经济机制提供了理论依据. 相似文献