全文获取类型
收费全文 | 3644篇 |
免费 | 169篇 |
国内免费 | 14篇 |
专业分类
化学 | 2889篇 |
晶体学 | 25篇 |
力学 | 42篇 |
数学 | 393篇 |
物理学 | 478篇 |
出版年
2023年 | 28篇 |
2022年 | 22篇 |
2021年 | 39篇 |
2020年 | 61篇 |
2019年 | 47篇 |
2018年 | 35篇 |
2017年 | 29篇 |
2016年 | 115篇 |
2015年 | 122篇 |
2014年 | 105篇 |
2013年 | 170篇 |
2012年 | 242篇 |
2011年 | 264篇 |
2010年 | 159篇 |
2009年 | 104篇 |
2008年 | 203篇 |
2007年 | 204篇 |
2006年 | 187篇 |
2005年 | 200篇 |
2004年 | 197篇 |
2003年 | 164篇 |
2002年 | 131篇 |
2001年 | 86篇 |
2000年 | 63篇 |
1999年 | 55篇 |
1998年 | 40篇 |
1997年 | 48篇 |
1996年 | 47篇 |
1995年 | 38篇 |
1994年 | 30篇 |
1993年 | 30篇 |
1992年 | 33篇 |
1991年 | 24篇 |
1990年 | 27篇 |
1989年 | 24篇 |
1988年 | 32篇 |
1987年 | 21篇 |
1986年 | 18篇 |
1985年 | 19篇 |
1984年 | 28篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1981年 | 21篇 |
1979年 | 13篇 |
1978年 | 26篇 |
1977年 | 12篇 |
1976年 | 12篇 |
1968年 | 15篇 |
1965年 | 18篇 |
1964年 | 11篇 |
排序方式: 共有3827条查询结果,搜索用时 125 毫秒
1.
2.
J. Krause und F. Umland 《Fresenius' Journal of Analytical Chemistry》1989,335(7):791-795
Summary This paper presents some applications of cyclic voltammetry at the interface of two immiscible electrolyte solutions by means of an experimental set-up described in a former publication. When using special sample preparation good results are obtained for the determination of iodide and quinine in pharmaceutical products as well as for the determination of quinine in tonic water and dodecylsulfate in a tooth-salt.
Herrn Prof. Dr. Günther Tölg zum 60. Geburtstag gewidmet 相似文献
Herrn Prof. Dr. Günther Tölg zum 60. Geburtstag gewidmet 相似文献
3.
P. Santhana Gopala Krishnan Chaobin He Christine Tay Shang Shang 《Journal of polymer science. Part A, Polymer chemistry》2004,42(16):4036-4046
Two ladder‐like polysilsesquioxanes (LPS) containing side‐chain maleimide groups have been synthesized successfully by reacting N‐(4‐hydroxyphenyl)maleimide (HPM) with LPS containing 100 mol % of chloropropyl groups (Ladder A ) and 50 mol % of each methyl and chloropropyl group (Ladder B ). HPM was synthesized by reacting maleic anhydride with 4‐aminophenol, and the resulting amic acid was imidized using p‐toluenesulfonic acid as a catalyst (Scheme 1 ). The LPSs were characterized by Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (NMR), proton‐decoupled 13C NMR, 29Si NMR, wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Characterization indicated that these polymers had ordered ladder‐like structures with possible defects. These polymers were soluble in common solvents at ambient temperature, which suggested that they were not crosslinked. Both the polymers and the HPM were cured, and their kinetics were followed by dynamic DSC. The Ozawa and Kissinger methods were used to calculate activation energies for curing. Curing increased the temperature at which both 5% weight loss and maximum rate of weight loss were observed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4036–4046, 2004 相似文献
4.
5.
6.
7.
G.Biju Kumar Hetal.V Patel Amrish C Shah Markus Trenkle Christine J Cardin 《Tetrahedron: Asymmetry》1996,7(12):3391-3396
N-Arylsulfonamides of (R)- and (S)-2-amino-1-butanol, on condensation with aromatic aldehydes produced diastereomerically pure 2-aryl-3-arenesulfonyl 4-ethyl-1,3-oxazolidines. The absolute configurations of one enantiomeric pair have been determined from two fully refined X-ray structures, supplemented by nmr data. 相似文献
8.
Christine Bessenrodt 《Annals of Combinatorics》1998,2(2):103-110
The well-known fact that there is always one more addable than removable box for a Young diagram is generalized to arbitrary hooks. As an application, this immediately implies a simple proof of a conjecture of Regev and Vershik [3] for which inductive proofs have recently been given by Regev and Zeilberger [4] and Janson [1]. 相似文献
9.
10.