全文获取类型
收费全文 | 28281篇 |
免费 | 4624篇 |
国内免费 | 2943篇 |
专业分类
化学 | 18625篇 |
晶体学 | 268篇 |
力学 | 1977篇 |
综合类 | 217篇 |
数学 | 3611篇 |
物理学 | 11150篇 |
出版年
2024年 | 108篇 |
2023年 | 597篇 |
2022年 | 1085篇 |
2021年 | 1118篇 |
2020年 | 1111篇 |
2019年 | 1060篇 |
2018年 | 986篇 |
2017年 | 931篇 |
2016年 | 1366篇 |
2015年 | 1321篇 |
2014年 | 1557篇 |
2013年 | 2083篇 |
2012年 | 2460篇 |
2011年 | 2485篇 |
2010年 | 1670篇 |
2009年 | 1625篇 |
2008年 | 1779篇 |
2007年 | 1532篇 |
2006年 | 1402篇 |
2005年 | 1188篇 |
2004年 | 878篇 |
2003年 | 707篇 |
2002年 | 635篇 |
2001年 | 533篇 |
2000年 | 529篇 |
1999年 | 636篇 |
1998年 | 538篇 |
1997年 | 536篇 |
1996年 | 510篇 |
1995年 | 480篇 |
1994年 | 399篇 |
1993年 | 351篇 |
1992年 | 286篇 |
1991年 | 254篇 |
1990年 | 239篇 |
1989年 | 190篇 |
1988年 | 147篇 |
1987年 | 125篇 |
1986年 | 98篇 |
1985年 | 97篇 |
1984年 | 65篇 |
1983年 | 51篇 |
1982年 | 52篇 |
1981年 | 22篇 |
1980年 | 12篇 |
1979年 | 4篇 |
1976年 | 1篇 |
1959年 | 1篇 |
1957年 | 7篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
In the present paper, we prove that the Bernstein-Kantorovič operators have the ability of preserving translation property
in both C and Lp norms.
Supported (in part) by the NSFC(10471130,10371024) of PRC and the Natural Science Foundation (Y604003) of Zhejiang Province. 相似文献
72.
Chongyi Wan Shiming Liu Rongqing Tan Jin Wu Jinwen Zhou Yan Lv Yanning Yu Hua Yang 《Optics & Laser Technology》2004,36(8):2389-649
A high average power, high-repetition-rate TEA CO2 laser employing printed-circuit-board preionizer is described. The power scaling of this preionization configuration has been demonstrated. The average output power reaches 3.6 kW at pulse repetition rate of 180 pps. Furthermore, the scaling-up ability of the rotating spark gap as high-voltage switch for high-average-power gas laser has been validated. 相似文献
73.
Felipe Cucker Steve Smale Ding-Xuan Zhou 《Foundations of Computational Mathematics》2004,4(3):315-343
We describe a model for the evolution of the languages used by the agents of a
society. Our main result proves convergence of these languages to a common
one under certain conditions. A few special cases are elaborated in more
depth. 相似文献
74.
Wei Hong Jinxiong Zhou Zhigang Suo 《Journal of the mechanics and physics of solids》2008,56(5):1779-1793
A large quantity of small molecules may migrate into a network of long polymers, causing the network to swell, forming an aggregate known as a polymeric gel. This paper formulates a theory of the coupled mass transport and large deformation. The free energy of the gel results from two molecular processes: stretching the network and mixing the network with the small molecules. Both the small molecules and the long polymers are taken to be incompressible, a constraint that we enforce by using a Lagrange multiplier, which coincides with the osmosis pressure or the swelling stress. The gel can undergo large deformation of two modes. The first mode results from the fast process of local rearrangement of molecules, allowing the gel to change shape but not volume. The second mode results from the slow process of long-range migration of the small molecules, allowing the gel to change both shape and volume. We assume that the local rearrangement is instantaneous, and model the long-range migration by assuming that the small molecules diffuse inside the gel. The theory is illustrated with a layer of a gel constrained in its plane and subject to a weight in the normal direction. We also predict the scaling behavior of a gel under a conical indenter. 相似文献
75.
76.
GFFs with less than 0.4 dB peak-to-peak error functions are routinely fabricated using commercially available coating machines by utilizing the natural error compensation mechanism of wavelength variable turning point optical monitoring method. 相似文献
77.
Yanqing Tian Xiaohe Xu Yingying Zhao Xinyi Tang Fengyu Su Xiaoguang Zhao Enle Zhou 《Liquid crystals》1995,19(3):295-300
The synthesis of three new series of chiral Schiff's bases containing benzilideneaniline and 2-hydroxybenzilideneaniline moieties as mesogenic cores is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements were used to study the phase transition temperatures and behaviour. The results reveal that most of these materials show chiral smectic mesomorphism. 相似文献
78.
X. S. Wu Xuehai Wu Yunping Li Zhangde Lu Liangen Gong Ping Zhou Qing Zhang 《Fiber and Integrated Optics》1993,12(1):97-103
Miniature, etching ridge InGaAsP/InP Phase Modulator with highly efficient phase shifting efficiency of 60°/V.mm and 43°/V.mm for TE and TM modes, respectively, and 3 dB bandwidth of 650 MHz at 1.52 μm are reported. It is well suited for integrated opto-electronics. Some functions depending on bandwidth of the devices are discussed. 相似文献
79.
对任一函数f∈Lp[0,1],n阶Bernstein—Durrnieyer算子为 相似文献
80.
The line search method incorporating the Wolfe conditions is modified to ensure that a descent algorithm terminates in a finite number of steps at an approximate stationary point where the second-order conditions of optimality are satisfied. A simple procedure based on conjugate directions is proposed to determine directions of negative curvature. 相似文献