全文获取类型
收费全文 | 75159篇 |
免费 | 925篇 |
国内免费 | 369篇 |
专业分类
化学 | 27702篇 |
晶体学 | 1027篇 |
力学 | 3202篇 |
综合类 | 8篇 |
数学 | 4680篇 |
物理学 | 23824篇 |
无线电 | 16010篇 |
出版年
2022年 | 567篇 |
2021年 | 527篇 |
2020年 | 483篇 |
2019年 | 480篇 |
2018年 | 645篇 |
2017年 | 553篇 |
2016年 | 989篇 |
2015年 | 696篇 |
2014年 | 1120篇 |
2013年 | 2721篇 |
2012年 | 2504篇 |
2011年 | 3256篇 |
2010年 | 2470篇 |
2009年 | 2693篇 |
2008年 | 3405篇 |
2007年 | 3563篇 |
2006年 | 3358篇 |
2005年 | 2979篇 |
2004年 | 2779篇 |
2003年 | 2427篇 |
2002年 | 2303篇 |
2001年 | 3658篇 |
2000年 | 2751篇 |
1999年 | 2055篇 |
1998年 | 1575篇 |
1997年 | 1583篇 |
1996年 | 1376篇 |
1995年 | 1277篇 |
1994年 | 1184篇 |
1993年 | 1156篇 |
1992年 | 1472篇 |
1991年 | 1487篇 |
1990年 | 1357篇 |
1989年 | 1140篇 |
1988年 | 1073篇 |
1987年 | 975篇 |
1986年 | 825篇 |
1985年 | 1069篇 |
1984年 | 1024篇 |
1983年 | 699篇 |
1982年 | 708篇 |
1981年 | 668篇 |
1980年 | 593篇 |
1979年 | 705篇 |
1978年 | 719篇 |
1977年 | 715篇 |
1976年 | 625篇 |
1975年 | 543篇 |
1974年 | 565篇 |
1973年 | 486篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Y. Tanabe T. Adachi H. Sato T. Sasaki Y. Koike 《Journal of Physics and Chemistry of Solids》2008,69(12):3217-3220
We have measured the temperature dependence of the magnetic susceptibility, χ vs. T, and the magnetization curve, M vs. H, for NbSe2 single crystals, in order to compare the superconducting (SC) state in the overdoped regime of La2−xSrxCuO4 (LSCO) with the SC state of the layered conventional superconductor NbSe2. While a plateau in χ vs. T in a moderate magnetic field and a so-called second peak in M vs. H, which is due to the marked enhancement of vortex pinning, have been observed in the overdoped regime of LSCO, these behaviors have not been observed in NbSe2. The present results indicate that the anomalously marked enhancement of vortex pinning is a characteristic feature in the overdoped LSCO where a microscopic phase separation into SC and normal-state regions takes place. 相似文献
942.
943.
A. A. Andronov A. V. Ikonnikov K. V. Maremianin V. I. Pozdnjakova Y. N. Nozdrin A. A. Marmalyuk A. A. Padalitsa M. A. Ladugin V. A. Belyakov I. V. Ladenkov A. G. Fefelov 《Semiconductors》2018,52(4):431-435
Narrow band emissions at 2.6–2.8 THz are observed out of liquid helium cooled 1 mm disk chips prepared of a wafer with the very low n type doped weak barrier GaAs–GaAlAs superlattice of 1000 periods. The emissions are at about 8.0–18.0 V pulsed voltage applied to the chips in region of the chips positive DC differential conductivity that guaranties absence of inhomogeneous electric field domains in the chips. The emission frequency bands are estimated with a cyclotron resonance filter; the measurements show that the band width is of about that of the THz quantum cascade laser. By using long voltage pulses the chip heating above 100 K is achieved without substantial change in emission power. We speculate that the emission is super luminescence (amplification) of whispering gallery modes in the chips as a result of inverted Wannier-Stark level transitions under bias. The results are the first world demonstration of THz stimulated emission in a simple superlattice within region of positive DC differential conductivity; they give strong impetus for development of THz and higher frequency sources based on such simple superlattices; the sources should well compete with the THz quantum cascade lasers in particular at elevated temperatures. 相似文献
944.
Zavrazhnov A. Y. Semenova G. V. Proskurina E. Y. Sushkova T. P. 《Journal of Thermal Analysis and Calorimetry》2018,134(1):475-481
Journal of Thermal Analysis and Calorimetry - The T–x diagram of the Sn–P system was studied by differential thermal analysis, X-ray phase analysis and local X-ray spectral... 相似文献
945.
Babanly N. B. Imamaliyeva S. Z. Yusibov Y. A. Taghiyev D. B. Babanly M. B. 《Journal of Solid State Electrochemistry》2018,22(4):1143-1148
Journal of Solid State Electrochemistry - The Ag-Tl-Se ternary system in the composition region Ag2Se-Tl2Se-Se was studied in the temperature range 300–450 K by measuring the electromotive... 相似文献
946.
Technical Physics - Bilayer CoSi2/Si/CoSi2/Si system has been obtained by the method of ion implantation, and optimal conditions for implantation and postimplantation annealing have been found. It... 相似文献
947.
948.
Graphene with a periodic array of defects in a homogeneous magnetic field is considered. We suggest a solvable model of the system. Three types of defects are studied. The spectra of the Hamiltonians have the Hofstadter butterfly type. The comparison of the spectrum for pure graphene and one for the system having defects of each type is made. 相似文献
949.
We study the thermodynamical features and dynamical evolutions of various apparent horizons associated with the Vaidya evaporating black hole surrounded by the cosmological fields of dust, radiation, quintessence, cosmological constant-like and phantom. In this regard, we address in detail how do these surrounding fields contribute to the characteristic features of a surrounded dynamical black hole in comparison to a dynamical black hole in an empty background. 相似文献
950.
Y. T. Angel Wong Vinicius Martins Dr. Bryan E. G. Lucier Prof. Dr. Yining Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(8):1848-1853
Metal–organic frameworks (MOFs) have shown great potential in gas separation and storage, and the design of MOFs for these purposes is an on-going field of research. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a valuable technique for characterizing these functional materials. It can provide a wide range of structural and motional insights that are complementary to and/or difficult to access with alternative methods. In this Concept article, the recent advances made in SSNMR investigations of small gas molecules (i.e., carbon dioxide, carbon monoxide, hydrogen gas and light hydrocarbons) adsorbed in MOFs are discussed. These studies demonstrate the breadth of information that can be obtained by SSNMR spectroscopy, such as the number and location of guest adsorption sites, host–guest binding strengths and guest mobility. The knowledge acquired from these experiments yields a powerful tool for progress in MOF development. 相似文献