全文获取类型
收费全文 | 10711篇 |
免费 | 1996篇 |
国内免费 | 1657篇 |
专业分类
化学 | 8480篇 |
晶体学 | 156篇 |
力学 | 643篇 |
综合类 | 105篇 |
数学 | 1413篇 |
物理学 | 3567篇 |
出版年
2024年 | 18篇 |
2023年 | 157篇 |
2022年 | 304篇 |
2021年 | 373篇 |
2020年 | 400篇 |
2019年 | 459篇 |
2018年 | 374篇 |
2017年 | 337篇 |
2016年 | 544篇 |
2015年 | 629篇 |
2014年 | 637篇 |
2013年 | 795篇 |
2012年 | 935篇 |
2011年 | 939篇 |
2010年 | 767篇 |
2009年 | 729篇 |
2008年 | 765篇 |
2007年 | 628篇 |
2006年 | 557篇 |
2005年 | 516篇 |
2004年 | 475篇 |
2003年 | 439篇 |
2002年 | 543篇 |
2001年 | 437篇 |
2000年 | 290篇 |
1999年 | 231篇 |
1998年 | 201篇 |
1997年 | 139篇 |
1996年 | 129篇 |
1995年 | 116篇 |
1994年 | 90篇 |
1993年 | 70篇 |
1992年 | 57篇 |
1991年 | 59篇 |
1990年 | 40篇 |
1989年 | 29篇 |
1988年 | 24篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
61.
Ying‐Ling Liu Chuan‐Shao Wu Yie‐Shun Chiu Wen‐Hsuan Ho 《Journal of polymer science. Part A, Polymer chemistry》2003,41(15):2354-2367
A novel epoxy system was developed through the in situ curing of bisphenol A type epoxy and 4,4′‐diaminodiphenylmethane with the sol–gel reaction of a phosphorus‐containing trimethoxysilane (DOPO–GPTMS), which was prepared from the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) with 3‐glycidoxypropyltrimethoxysilane (GPTMS). The preparation of DOPO–GPTMS was confirmed with Fourier transform infrared, 1H and 31P NMR, and elemental analysis. The resulting organic–inorganic hybrid epoxy resins exhibited a high glass‐transition temperature (167 °C), good thermal stability over 320 °C, and a high limited oxygen index of 28.5. The synergism of phosphorus and silicon on flame retardance was observed. Moreover, the kinetics of the thermal oxidative degradation of the hybrid epoxy resins were studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2354–2367, 2003 相似文献
62.
In this article a new technique was developed to fabricate scaffolds with a unique microstructure by solid–liquid separation in combination with particulate-leaching. Firstly, the effects of polymer concentration, quenching temperature on the porous morphology and the mechanical property of obtained scaffolds during solid–liquid separation have been investigated. Then, salt granules as porogen were introduced into the solid–liquid phase separation to produce the unique pore structure of the scaffold. The pore diameter of the scaffold could be controlled with the particulate size and the wall of pores possessed special microstructure, which enhanced the pore interconnectivity. The cell culture results confirmed that a good interconnectivity of the scaffold prepared by the improved solid–liquid separation was useful for nutrition transportation and cell proliferation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
63.
Three mechanisms to reduce threading dislocations(TDs) in GaN films as the epitaxial films grow thicker are suggested by SEM and TEM 相似文献
64.
65.
Analytic solutions of an iterative functional equation 总被引:4,自引:0,他引:4
66.
67.
Two homologous series of mesogenic materials which incorporate a 1,4-tetrafluorophenylene moiety and a terminal cyano- or nitro-substituent have been synthesized by using palladiumcatalysed coupling procedures. The compounds exhibit nematic and/or smectic A phases. 相似文献
68.
Y. H. Zhang X. H. Zhou Q. Z. Zhao X. F. Sun X. G. Lei Y. X. Guo Z. Liu X. F. Chen Y. T. Zhu S. X. Wen G. J. Yuan X. A. Liu 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):335-336
High spin states of the odd-odd162Lu nucleus have been studied via147Sm(19F,4nγ)162Lu reaction at 95 MeV beam energy. Level scheme for yrast band based onπ[h11/2 v[i13/2] quasiparticle configuration was established up to I π = (23?) for the first time. This band shows the signature inversion in energy before backbending generally appeared in this mass region. It is stressed that the signature splitting in162Lu is larger than that in the160Tm nucleus. 相似文献
69.
Based on the anisotropic Seebeck tensor coefficients, a light-thermo-radiation detector made of high-Tc superconductor (YBa2Cu3O7-δ) was fabricated, which can function at room temperature. The induced voltaic signals at various modulation frequencies for radiation from He-Ne laser and from a 500 K black body were measured. The noise ratio for detecting He-Ne laser radiation and the D* for black body were evaluated. Compared with bolometer made of high-Tc superconductor which functions at liquid nitrogen, and with pyroelectric detector, it was found that the advantages of this new device are that the device can work at room temperature with very low noise and very fast response. Although having a lower D* value than that of bolometer for the present device construction, we point out the possibility and the direction for improving the D* value, hence the promising prospect of this kind of device. 相似文献
70.
Hua Ning LIU Wen Peng ZHANG 《数学学报(英文版)》2007,23(5):915-924
The main purpose of this paper is to use the generalized Bernoulli numbers, Gauss sums and the mean value theorems of Dirichlet L-functions between a quadratic residue and its inverse modulo p value formula. to study the asymptotic property of the difference (a prime), and to give an interesting hybrid mean 相似文献