全文获取类型
收费全文 | 76559篇 |
免费 | 11596篇 |
国内免费 | 19983篇 |
专业分类
化学 | 53600篇 |
晶体学 | 2393篇 |
力学 | 5576篇 |
综合类 | 1961篇 |
数学 | 11661篇 |
物理学 | 32947篇 |
出版年
2023年 | 657篇 |
2022年 | 2173篇 |
2021年 | 2294篇 |
2020年 | 2385篇 |
2019年 | 2403篇 |
2018年 | 2342篇 |
2017年 | 3123篇 |
2016年 | 2750篇 |
2015年 | 3239篇 |
2014年 | 4083篇 |
2013年 | 5300篇 |
2012年 | 5418篇 |
2011年 | 5782篇 |
2010年 | 5634篇 |
2009年 | 5752篇 |
2008年 | 6368篇 |
2007年 | 5865篇 |
2006年 | 5390篇 |
2005年 | 4626篇 |
2004年 | 3667篇 |
2003年 | 2721篇 |
2002年 | 2811篇 |
2001年 | 2779篇 |
2000年 | 2788篇 |
1999年 | 1665篇 |
1998年 | 1038篇 |
1997年 | 820篇 |
1996年 | 767篇 |
1995年 | 745篇 |
1994年 | 706篇 |
1993年 | 729篇 |
1992年 | 690篇 |
1991年 | 566篇 |
1990年 | 603篇 |
1989年 | 589篇 |
1988年 | 424篇 |
1987年 | 440篇 |
1986年 | 389篇 |
1985年 | 413篇 |
1984年 | 435篇 |
1983年 | 362篇 |
1982年 | 363篇 |
1979年 | 379篇 |
1978年 | 356篇 |
1976年 | 421篇 |
1975年 | 366篇 |
1974年 | 404篇 |
1973年 | 402篇 |
1972年 | 371篇 |
1971年 | 343篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
Dr. Wan‐Ling Liu Ni‐Shin Yang Ya‐Ting Chen Stephen Lirio Cheng‐You Wu Prof. Chia‐Her Lin Prof. Hsi‐Ya Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):115-119
A green and sustainable strategy synthesizes clinical medicine warfarin anticoagulant by using lipase‐supported metal–organic framework (MOF) bioreactors (see scheme). These findings may be beneficial for future studies in the industrial production of chemical, pharmaceutical, and agrochemical precursors. 相似文献
22.
Chao Liu Liying Wang Lin Yang Famei Wang Chunhong Xu Jingwei Lv Guanglai Fu Xianli Li Qiang Liu Haiwei Mu Tao Sun Paul K. Chu 《Physics letters. A》2019,383(25):3200-3206
A single-polarization filter comprising a gold-coated photonic crystal fiber based on surface plasmon resonance is designed and investigated. The pattern matching and coupled polarization characteristics analyzed by the full-vector finite element method (FEM) and losses at 1,540 nm are achieved to 1,016.01739 dB/cm (x-pol core mode) and 33.81917 dB/cm (y-pol core mode). The crosstalk (CT) value of the 1,540 nm band is ?853.12653 dB for fiber length and the bandwidth is 850 nm. The working wavelength of the filter ranges from 1,280 nm to 1,540 nm by varying the diameter of outer air holes (), the diameter of inner air holes (), the metal film thickness (t), as well as the liquid refractive index (n). 相似文献
23.
Alessandro Morando Paola Trebeschi Tao Wang 《Journal of Differential Equations》2019,266(9):5397-5430
We show the short-time existence and nonlinear stability of vortex sheets for the nonisentropic compressible Euler equations in two spatial dimensions, based on the weakly linear stability result of Morando and Trebeschi (2008) [20]. The missing normal derivatives are compensated through the equations of the linearized vorticity and entropy when deriving higher-order energy estimates. The proof of the resolution for this nonlinear problem follows from certain a priori tame estimates on the effective linear problem in the usual Sobolev spaces and a suitable Nash–Moser iteration scheme. 相似文献
24.
25.
The stable phase equilibria of quaternary systems LiBr-NaBr-MgBr2-H2O and LiBr-KBr-MgBr2-H2O at 298.15 K were studied by both experimental measurement(isothermal solution saturation method) and theoretical prediction(Pitzer model). The solubilities of the saturated solution have been determined experimentally and two stable phase diagrams and relevant water diagrams of the two quaternary systems were obtained. Results show that quaternary system LiBr-NaBr-MgBr2-H2O is hydrate II type as NaBr and NaBr·2H2O coexistence. Its phase diagram consists of only one invariant point, four univariant curves, and five crystallization fields. The quaternary system LiBr-KBr-MgBr2-H2O is a complex type as the double salt KBr·MgBr2·6H2O formed. In addition to this double salt, the three single salts LiBr·2H2O, KBr and MgBr2·6H2O also crystallize. In this paper, the solubilities of phase equilibria in above quaternary systems were also calculated by the Pitzer's electrolyte solution model. All the needed parameters can be obtained from the literature or be fitted by experimental data. On the Basis of the experimental and calculated results, the phase diagram of the quaternary system was plotted for comparison. It shows that the calculation results are consistent with the experimental ones. 相似文献
26.
27.
28.
29.
近年来,基于透射电子显微技术、微纳加工技术和薄膜制造技术的发展,原位液相透射电子显微技术产生,为构建多种纳米级分辨率尺度下的微实验平台,发展新型纳米表征技术和众多领域的相关研究提供了途径.本文首先介绍了应用于原位液相透射电子显微技术的液体腔设计要求,然后介绍了液体腔的发展和典型的制备工艺,最后综述了近年来液体腔透射电子显微镜在纳米粒子成核和生长方面的应用研究,并探讨了该技术前沿发展面临的机遇和挑战.本文将为提高我国先进纳米表征技术和原子精准构筑技术提供相关讨论和支持. 相似文献
30.
Stadnyk V. Yo. Shchepanskyi P. A. Rudysh M. Ya. Kogut Z. A. 《Journal of Applied Spectroscopy》2021,88(4):831-837
Journal of Applied Spectroscopy - The temperature dependence of the refractive indices of K2SO4 with copper impurity was investigated. It was found that introduction of the copper impurity leads to... 相似文献