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   215575篇
  免费   1568篇
  国内免费   627篇
化学   118042篇
晶体学   3271篇
力学   8351篇
综合类   6篇
数学   23314篇
物理学   64786篇
  2020年   1974篇
  2019年   2267篇
  2018年   3209篇
  2017年   3115篇
  2016年   4270篇
  2015年   2372篇
  2014年   3824篇
  2013年   9269篇
  2012年   6902篇
  2011年   8454篇
  2010年   6077篇
  2009年   5927篇
  2008年   8145篇
  2007年   8218篇
  2006年   7636篇
  2005年   6942篇
  2004年   6172篇
  2003年   5646篇
  2002年   5499篇
  2001年   5941篇
  2000年   4684篇
  1999年   3472篇
  1998年   3010篇
  1997年   3033篇
  1996年   2823篇
  1995年   2319篇
  1994年   2420篇
  1993年   2451篇
  1992年   2597篇
  1991年   2657篇
  1990年   2559篇
  1989年   2533篇
  1988年   2463篇
  1987年   2434篇
  1986年   2357篇
  1985年   3037篇
  1984年   3195篇
  1983年   2559篇
  1982年   2827篇
  1981年   2704篇
  1980年   2503篇
  1979年   2718篇
  1978年   2833篇
  1977年   2856篇
  1976年   2832篇
  1975年   2687篇
  1974年   2665篇
  1973年   2810篇
  1972年   1875篇
  1967年   1830篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
122.
We present kinetic inductance measurements in current driven Josephson junction arrays. Measurements performed with circular coils indicate that this technique is very sensitive to the vortex mobility. Results obtained with anisotropic detection coils provide experimental evidence for the anisotropic response of a driven vortex lattice. Anisotropic behavior is obtained when rising the temperature or the mean vortex velocity as indicated by the loss of the superconducting shielding capability, first in the direction of vortex motion and then in the perpendicular direction.  相似文献   
123.
We construct an integral Newton-type interpolation polynomial with a continual set of nodes. This interpolant is unique and preserves an operator polynomial of the corresponding degree.  相似文献   
124.
A tight-binding (TB) hamiltonian for calcium is built with a high precision parametrization technique based on density functional calculations of the energy bands and the total energy at various lattice volumes. The new set of TB parameters is appropriate to study phenomena under pressures as high as 20 GPa. Specifically, both the metal to nonmetal transition at 4 GPa and the structural transition fcc to bcc at 19 GPa are well reproduced. These transitions and several static properties are in excellent agreement with experiments. Phonon frequencies, plasmon energy, melting temperature and the coefficient of thermal expansion were calculated with a molecular dynamics scheme of this TB hamiltonian.  相似文献   
125.
Using a convergence theorem for Fourier–Padé approximants constructed from orthogonal polynomials on the unit circle, we prove an analogue of Hadamard's theorem for determining the radius of m-meromorphy of a function analytic on the unit disk and apply this to the location of poles of the reciprocal of Szeg functions.  相似文献   
126.
127.
128.
Microstructure and oxygen stoichiometry of YBaCuO films manufactured by laser ablation are investigated. Dependence of the specific electrical resistivity and superconducting parameters of films on microstructure and oxygen stoichiometry is demonstrated. Conditions of deposition are determined, under which films with minimum microstructure defects and good conducting properties are formed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 41–45, February, 2007.  相似文献   
129.
This paper reports a successful achievement of laser-induced biological cell fusion using an excimer laser excited dye laser. To our knowledge, we examined for the first time the dependence of fusion rate on laser pulse energy, number of laser pulses, and laser wavelength. Maximum fusion rate of approximately 50% was obtained by this laser fusion technology.  相似文献   
130.
A number of phenomena connected with the formation of electrode jets in discharges in hydrogen at a current of 10/sup 5/-10/sup 6/ A, a current growth rate of 10/sup 10/ A/s, an initial pressure 0.1-4.0 MPa, and a discharge gap length of 5-40 mm were studied. After the secondary breakdown, the jets are observed through a discharge semitransparent channel, widening with velocity (4-7) /spl middot/ 10/sup 2/ m/s. Shockwave formation was detected at the interaction of jets with the surrounding gas and the opposite electrode. Plasma vapor pressure of metal near the end of the tungsten cathode 70 /spl mu/s after initiation of a discharge was 180 MPa. Thus, magnitude of brightness temperature was 59 /spl middot/ 10/sup 3/ K, with an average charge of ions-m~=3.1, and a concentration of metal vapors n=5.3/spl middot/10/sup 19/ cm/sup -3/. While those at the end of the anode 90 /spl mu/s after initiation of discharge: m~=2.6, n=7.4/spl middot/10/sup 19/ cm/sup -3/. Probable reasons of high-voltage drops near the electrodes (the summarized magnitude of which is /spl sim/1 kV) are discussed on the basis of experimental data. For the first time, the shadow method registered symmetric ejection of material from the all-cathode surface the maximum discharge current was observed.  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