全文获取类型
收费全文 | 14973篇 |
免费 | 2251篇 |
国内免费 | 3003篇 |
专业分类
化学 | 16771篇 |
晶体学 | 257篇 |
力学 | 504篇 |
综合类 | 122篇 |
数学 | 68篇 |
物理学 | 2505篇 |
出版年
2024年 | 56篇 |
2023年 | 216篇 |
2022年 | 499篇 |
2021年 | 691篇 |
2020年 | 1036篇 |
2019年 | 761篇 |
2018年 | 552篇 |
2017年 | 573篇 |
2016年 | 785篇 |
2015年 | 777篇 |
2014年 | 852篇 |
2013年 | 1420篇 |
2012年 | 1156篇 |
2011年 | 838篇 |
2010年 | 649篇 |
2009年 | 747篇 |
2008年 | 792篇 |
2007年 | 817篇 |
2006年 | 831篇 |
2005年 | 801篇 |
2004年 | 795篇 |
2003年 | 658篇 |
2002年 | 581篇 |
2001年 | 401篇 |
2000年 | 405篇 |
1999年 | 300篇 |
1998年 | 278篇 |
1997年 | 273篇 |
1996年 | 260篇 |
1995年 | 263篇 |
1994年 | 205篇 |
1993年 | 172篇 |
1992年 | 183篇 |
1991年 | 117篇 |
1990年 | 95篇 |
1989年 | 74篇 |
1988年 | 55篇 |
1987年 | 53篇 |
1986年 | 32篇 |
1985年 | 32篇 |
1984年 | 20篇 |
1983年 | 15篇 |
1982年 | 20篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1979年 | 14篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
载能离子穿过固体界面引起界面原子迁移使界面原子混合和物质成分变化,从而导致界面发生材料相变。简要介绍了载能离子辐照引起金属/绝缘体界面混合效应及相变现象的主要实验研究进展、低能离子和高能离子辐照引起金属/绝缘体界面现象差异,并对离子辐照引起界面混合及相变的机制进行了初步探讨。When penetrating an interface between two kind of solids, energetic ions can induce atomic diffusion at both sides of the interface and then result in intermixing, atom re-distribution or composition change, as well as phase transformation. Main progress on the study of intermixing and phase change at metal/insulator interface induced by energetic ion irradiations, the difference of phenomena occurred at metal/insulator interfaces induced by high-and low-energy ions were briefly reviewed. Furthermore, the possible mechanisms related to intermixing and phase change at metal/insulator interface produced by energetic ion irradiations were also discussed in short words. 相似文献
52.
We present a model arising from the thermal modelling of two metal casting processes. We consider an enthalpy formulation for this two‐phase Stefan problem in a time varying three‐dimensional domain and consider convective heat transfer in the liquid phase. Then, we introduce a weak formulation in a fixed domain, by means of a suitable transformation. Existence of solution is obtained by applying an abstract theorem. The proof of this theorem is done by taking an implicit discretization in time together with a regularization. By passing to the limit in the regularization parameter and in the time step, we obtain the existence of solution of the continuous problem. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
53.
54.
Vaporizing solid samples of metals and semiconductors with a YAG Laser is a method well suited for producing molecules and
clusters of those materials. The clusters are examined by either laser-induced fluorescence (LIF) or mass spectroscopic methods.
The technique is valuable for both gas phase and matrix studies. The method is described and some applications, studying either
the structure of small metal molecules or their reactions, are reviewed, with emphasis on our recent results from the LIF
studies of LiBe, Al2 and the reaction of Al with oxygen, yielding A12O. For larger clusters, Ion Cyclotron Resonance is an extremely valuable method, as we demonstrate by its application to the
reactions of small charged silicon clusters with strong oxidising agents. 相似文献
55.
Takuya Hashimoto Koichi Kitazawa Masaaki Nakabayashi Tadashi Shiraishi Youichi Suemune Takakazu Yamamoto Hideomi Koinuma 《应用有机金属化学》1991,5(4):325-330
For low-temperature deposition of oxide films relating to Bi-Sr-Ca-Cu-O superconductors, photo-absorption and -decomposition properties were examined with respect to copper and alkaline-earth ß-diketonates. It was confirmed that all ß-diketonates examined were promising as source materials for photochemical vapour deposition (photo-CVD) using a low-pressure mercury lamp, in view of their large light absorption coefficients at wavelength 254 nm. The light irradiation was effective for the formation of highly crystalline oxide films at temperatures below 600 °C. By combining two sources, Ca2CuO3 and SrCuO2 films were prepared. Photo-CVD of c-axis oriented Bi2Sr2CuOx film was achieved by the irradiation of ternary sources of Bi(C6H5)3 and strontium and copper ß-diketonates at 500 °C. 相似文献
56.
E. A. Sokolov S. D. Babenko N. P. Piven’ A. N. Ponomarev 《Russian Chemical Bulletin》1997,46(4):826-828
Experimental results related to the transition of spontaneous polymerization of acrylamide complexes with metal nitrates to
the “explosive” regime at room temperature are presented. It is suggested that the “explosion” has a thermal nature.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 859–861, April, 1997. 相似文献
57.
F. M. Tukhtaboeva K. S. Davronov I. Zh. Kurbonbaev K. K. Kuchkarov 《Chemistry of Natural Compounds》2006,42(4):477-478
The protein composition of seeds treated with a suspension of ultradisperse iron was studied using electrophoresis on PAAG.
Changes were noted in the fractions with relative electrophoretic mobility (REM) 0.11 of water-soluble and REM 0.37 of buffer-soluble
An-9 cotton seed proteins.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 384–385, July–August, 2006. 相似文献
58.
The thermal dehydration of copper(II) acetate hydrate has been studied between 353 and 406 K, over a range of humidities.
The dehydration is controlled by nucleation-and-growth kinetics at low temperatures, with an activation energy of 154 kJ·mol−1, which changes to contracting-disc kinetics at higher temperatures with a lower activation energy of 76 kJ·mol−1. Frequency factors have also been derived; the value for the high temperature process is low (107s−1) and that for the low temperature step is high (1017s−1). Optical microscopy has been used to clarify the bulk kinetics; there is evidence for a reactive layer at the surface of
the decomposing solid.
In celebration of the 60th birthday of Dr Andrew K. Galwey 相似文献
59.
Chemisorption of polybenzimidazole on silver and copper etched with nitric acid has been observed by surface-enhanced Raman scattering (SERS). The polymer is found to react chemically with silver, forming a complexed film on the surface. The SERS spectra show that polybenzimidazole film inhibits oxidation of the metal at high temperature, unlike chemisorbed benzimidazole, benzotriazole, and poly(4-vinyl pyridine). © 1992 John Wiley & Sons, Inc. 相似文献
60.
Matrix-Investigations on Monomeric Copper(I) Chloride and its Complexes with N2 and PN Ligands. IR Spectroscopic Results and ab-initio Calculation In solid argon the reaction of monomeric CuCl with N2 yields ClCuN2. On the basis of two absorptions in the ir-spectrum and their corresponding isotopic shifts (14/15N) and with the help of a normal coordinate analysis, linearity of the molecule has been deduced. These results are confirmed by large scale ab-initio Calculations (CPF, MP2). Reaction of monomeric CuCl with molecular PN under matrix condition is shown to give rise to new absorptions in the IR spectrum which arev assigned to a linear molecule ClCuNP. 相似文献