全文获取类型
收费全文 | 1161篇 |
免费 | 39篇 |
国内免费 | 3篇 |
专业分类
化学 | 1036篇 |
晶体学 | 7篇 |
力学 | 7篇 |
数学 | 83篇 |
物理学 | 70篇 |
出版年
2023年 | 5篇 |
2022年 | 3篇 |
2021年 | 21篇 |
2020年 | 6篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 36篇 |
2015年 | 30篇 |
2014年 | 22篇 |
2013年 | 72篇 |
2012年 | 79篇 |
2011年 | 96篇 |
2010年 | 54篇 |
2009年 | 42篇 |
2008年 | 96篇 |
2007年 | 103篇 |
2006年 | 77篇 |
2005年 | 98篇 |
2004年 | 45篇 |
2003年 | 42篇 |
2002年 | 48篇 |
2001年 | 19篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 27篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 14篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有1203条查询结果,搜索用时 15 毫秒
101.
Jesse R. Williams Masaaki Kobata Igor Pis Eiji Ikenaga Takeharu Sugiyama Keisuke Kobayashi Naoki Ohashi 《Surface science》2011,605(13-14):1336-1340
The surface structure of a single-crystal ZnO wafer was studied by angle-resolved x-ray photoelectron spectroscopy (ARXPS) using synchrotron radiation. As a result, well-defined x-ray photoelectron diffraction (XPD) patterns were obtained for the (0001) and (000) polar surfaces using the photoemission from the Zn 2p3/2 and O 1s core levels. The XPD patterns were indexed assuming forward scattering of photoelectrons by neighboring ions. Further, the XPD patterns for the (0001) and (000) surfaces were different from each other, indicating the possibility for using the XPD technique for polarity determination. 相似文献
102.
103.
104.
105.
106.
Javier Ramos Víctor L. Cruz Javier Martínez‐Salazar Mikael Brasse Pilar Palma Juan Campora 《Journal of polymer science. Part A, Polymer chemistry》2010,48(5):1160-1165
The present computational study was designed to study the polymerization of ethylene catalyzed by a new Ni‐based PymNox organometallic compound. Recently, we have synthesized and tested the behavior of this type of catalyst in olefin polymerization. It has been experimentally observed that the unsubstituted catalyst Ni2 (aldimino PymNox catalyst ) is less active than the methyl substituted Ni1 (acetaldimino PymNox catalyst ) analogue. The reactivity of both catalysts was examined using density functional theory (DFT) models. Our results indicate that the methyl substituted Ni1 introduces some additional steric hindrance that probably renders a more suitable catalyst conformation for the monomer incorporation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1160–1165, 2010 相似文献
107.
Pilar Campíns Falcó Francisco Bosch Reig Ana Molina Benet 《Fresenius' Journal of Analytical Chemistry》1990,338(1):16-21
Summary This paper discusses the requirements and scope of application of the H-Point Standard Additions Method (HPSAM) for resolving binary mixtures. Various mixtures of dyes with extensively or completely overlapping spectra were assayed with accurate, precise results. The method thus developed was also applied to the spectrophotometric resolution of binary mixtures of phenol and o-cresol, the absorption bands of which lie in similar positions and feature similar absorptivities. 相似文献
108.
109.
A p-version finite element method has been used to calculate second-order pair and total correlation energies for closed-shell Mg and Ar. Comparison with the best results found in the literature suggests that the present values are the most accurate and that the method should perform comparatively better for heavier elements. © 1993 John Wiley & Sons, Inc. 相似文献
110.
The reaction between methyl N-acetyl-,β-didehydroalaninate and cyclopentadiene in the presence of several chiral Lewis acids is studied and the results obtained are compared with those described for the reactions of the same diene with chiral N-acetyl-,β-didehydroalaninates. In the presence of the titanium complex 24d methyl (1R,2R,4R) 2-acetamido-5-norbornen-2-carboxylate is preferably obtained. Thus, the reaction between methyl N-acetyl-(,β-didehydroalaninate and cyclopentadiene is a good method for the synthesis of (1S, 2R, 4R) 2-aminonorbomane-2-carboxylic acid. 相似文献