全文获取类型
收费全文 | 218998篇 |
免费 | 1682篇 |
国内免费 | 661篇 |
专业分类
化学 | 120190篇 |
晶体学 | 3283篇 |
力学 | 8471篇 |
综合类 | 6篇 |
数学 | 23906篇 |
物理学 | 65485篇 |
出版年
2021年 | 1844篇 |
2020年 | 2065篇 |
2019年 | 2364篇 |
2018年 | 3301篇 |
2017年 | 3194篇 |
2016年 | 4415篇 |
2015年 | 2482篇 |
2014年 | 3953篇 |
2013年 | 9509篇 |
2012年 | 7160篇 |
2011年 | 8711篇 |
2010年 | 6245篇 |
2009年 | 6069篇 |
2008年 | 8372篇 |
2007年 | 8406篇 |
2006年 | 7852篇 |
2005年 | 7135篇 |
2004年 | 6328篇 |
2003年 | 5767篇 |
2002年 | 5604篇 |
2001年 | 5991篇 |
2000年 | 4712篇 |
1999年 | 3509篇 |
1998年 | 3029篇 |
1997年 | 3055篇 |
1996年 | 2846篇 |
1995年 | 2341篇 |
1994年 | 2445篇 |
1993年 | 2460篇 |
1992年 | 2607篇 |
1991年 | 2671篇 |
1990年 | 2565篇 |
1989年 | 2538篇 |
1988年 | 2467篇 |
1987年 | 2436篇 |
1986年 | 2360篇 |
1985年 | 3044篇 |
1984年 | 3200篇 |
1983年 | 2567篇 |
1982年 | 2831篇 |
1981年 | 2708篇 |
1980年 | 2510篇 |
1979年 | 2723篇 |
1978年 | 2835篇 |
1977年 | 2857篇 |
1976年 | 2836篇 |
1975年 | 2689篇 |
1974年 | 2667篇 |
1973年 | 2811篇 |
1972年 | 1876篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
A. E. Zernov 《Ukrainian Mathematical Journal》1991,43(6):705-709
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 6, pp. 755–760, June, 1991. 相似文献
103.
104.
105.
106.
A combined-modality treatment program consisting of botulinum toxin injection (Botox) and voice therapy was used to treat 17 subjects diagnosed with adductor spasmodic dysphonia (ADD SD). Ten subjects with ADD SD served as the control and were given Botox only. Voice therapy after Botox injection was directed toward reducing the hyperfunctional vocal behaviors, primarily glottal overpressure at voice onset and anterior-posterior squeezing. The results indicated that subjects who underwent combined-modality treatment maintained significantly higher mean airflow rates for significantly longer periods. Moreover, there was a carryover effect in these patients when they received Botox only. Adductor spasmodic dysphonia is treated most effectively when intrinsic laryngeal muscle spasms are reduced or eliminated by Botox injection and extrinsic hyperfunctional vocal behaviors are treated with voice therapy 相似文献
107.
Studies show that branching the side chains of hexakis(acoyloxy)-benzenes (HAB) and -cyclohexanes (HAChx) does not modify the structure of the discotic mesophase formed. Shear fields appear to act on entire columns, not on individual discs, thereby causing alignment of columns in the shear direction. X-ray diffraction patterns of samples at temperatures between 30°C and 40°C above the clearing temperature provide evidence for the presence of mesophase order. 相似文献
108.
Differential cross sections of nucleons excited in photonuclear reactions in medium and heavy nuclei are studied by considering all relevant reaction mechanisms leading to the excitation of protons or neutrons. We take advantage of previous microscopic studies for the absorption and scattering of photons and photoproduced pions, and implement a simulation code in order to take into account the propagation of the nucleons as well as their collisions with other nucleons in the nuclear medium, which generate secondary excited nucleons. Comparison with experimental data is done. Cross sections for nucleon emission in coincidence with one pion are also calculated, and some coincidence observables are discussed. 相似文献
109.
G. M. Luke L. P. Le B. J. Sternlieb Y. J. Uemura J. H. Brewer R. Kadono R. F. Kiefl S. R. Kreitzman T. M. Riseman C. E. Stronach M. Davis S. Uchida H. Takagi Y. Tokura Y. Hidaka T. Murakami E. A. Early J. T. Markert M. B. Maple C. L. Seaman 《Hyperfine Interactions》1991,63(1-4):311-317
We report muon spin relaxation/rotation measurements on sintered powder samples of Nd2−x
Ce
x
CuO4−y
and a large single crystal of Nd2CuO4−y
. We find an electronic phase diagram which is quite similar to that of hole-doped superconductors such as La2−x
Sr
x
CuO4−y
, although the doping of electrons into the system is less efficient in destroying the static moments on the copper spins.
Static magnetic order in Nd2CuO4−y
appears below about 250 K, and two spin reorientations are seen atT=75 K andT=35 K. Measurements of the magnetic field penetration depth have been unsuccessful due to the rare-earth paramagnetism of
these materials. 相似文献
110.
Carl E. Gordon 《Geometriae Dedicata》1992,42(2):187-203
The symmetric group on k symbols is made to operate on a certain set of matrices in such a way that its orbits are in one-to-one correspondence with the orbits of the k-arcs of an N-dimensional projective space under the group of projectivities. This leads to a formula for the number of such orbits. 相似文献