全文获取类型
收费全文 | 2687篇 |
免费 | 102篇 |
国内免费 | 12篇 |
专业分类
化学 | 2019篇 |
晶体学 | 29篇 |
力学 | 23篇 |
数学 | 158篇 |
物理学 | 572篇 |
出版年
2023年 | 26篇 |
2021年 | 23篇 |
2020年 | 53篇 |
2019年 | 44篇 |
2018年 | 23篇 |
2017年 | 21篇 |
2016年 | 62篇 |
2015年 | 57篇 |
2014年 | 50篇 |
2013年 | 137篇 |
2012年 | 106篇 |
2011年 | 138篇 |
2010年 | 77篇 |
2009年 | 84篇 |
2008年 | 179篇 |
2007年 | 159篇 |
2006年 | 177篇 |
2005年 | 150篇 |
2004年 | 146篇 |
2003年 | 114篇 |
2002年 | 109篇 |
2001年 | 48篇 |
2000年 | 61篇 |
1999年 | 54篇 |
1998年 | 29篇 |
1997年 | 36篇 |
1996年 | 34篇 |
1995年 | 31篇 |
1994年 | 34篇 |
1993年 | 32篇 |
1992年 | 39篇 |
1991年 | 26篇 |
1990年 | 19篇 |
1989年 | 18篇 |
1988年 | 23篇 |
1987年 | 29篇 |
1986年 | 19篇 |
1985年 | 29篇 |
1984年 | 35篇 |
1983年 | 23篇 |
1982年 | 35篇 |
1981年 | 32篇 |
1980年 | 17篇 |
1979年 | 24篇 |
1978年 | 14篇 |
1977年 | 16篇 |
1976年 | 17篇 |
1974年 | 15篇 |
1973年 | 18篇 |
1968年 | 9篇 |
排序方式: 共有2801条查询结果,搜索用时 31 毫秒
21.
In connection with a characteristic feature of the effective optical potential in the Dirac approach two types of time delays are considered in the relativistic eikonal approximation. One is obtained from the scattering amplitude and the other given by the wave packet motion in the interaction region. These time delays turn out to differ in sign at intermediate energies, in contrast to the agreement between corresponding nonrelativistic time delays. 相似文献
22.
23.
Cyclic voltammetry of TEMPO in aqueous 0.1 M NaOH in the presence of glutathione (GSH) or cysteine (Cys) indicated the following points: (i) Both of the thiols rapidly formed adducts 3 with oxoammonium ion 1 anodically generated from TEMPO. (ii) 3 generated from GSH entered a succeeding reaction that generated N-oxide anion 2- (the reduced TEMPO). (iii) 3 produced from Cys remained intact over the time scale of voltammetry. A structural feature of GSH was considered to contribute to the observed behavior of this tripeptide. Possible structural features were evaluated by screening various thiols on the basis of whether they provided GSH-like voltammetric results. The 3-mercaptopropionamide group with an amide hydrogen in GSH was determined to be responsible for the observed difference between GSH and Cys. The likely function is to transform 3 from GSH into a 5-imino-1,2-oxathiolane intermediate, thereby releasing 2-. Product analysis for reactions of model thiols representing GSH and Cys with 1 provided support for this argument and suggested that the reaction of GSH or Cys with 1 would produce the corresponding disulfides, regardless of whether a five-membered ring intermediate was formed. The proposed function of the 3-mercaptopropionamide moiety of GSH may provide useful insight for the molecular design of exogenous thiol compounds as novel drugs for the treatment of GSH-depletion-related disorders. 相似文献
24.
Dedicated to Professor John C. Sheehan on the occasion of his sixty-fifth birthday. Chemical and biological modifications of bleomycin, an antitumor glycopeptide antibiotic, have been achieved by three procedures analogous to the modifications of penicillin. 相似文献
25.
26.
Chowdhury Wasimul Q. Idehara Kenji Maeda Isamu Umeda Fusako Yagi Kiyohito Miura Yoshiharu Mizoguchi Tadashi 《Applied biochemistry and biotechnology》1996,57(1):361-366
Applied Biochemistry and Biotechnology - A marine photosynthetic bacterium,Rhodopseudomonas sp. strain W-1S, accumulated polyhydroxybutyrate (PHB) to 56% of the dry cell weight under microaerobic... 相似文献
27.
28.
29.
30.
The effect of solid particles on the flow structure of a round air jet in a stagnant surrounding was investigated experimentally. Information on the averaged two-component velocities, the kinetic energies, and the u′ v′-properties were obtained for both phases by means of a monochromatic three beam laser Doppler anemometer. The particle number density was also measured by this system. Glass beads of 64 μm and 132 μm diameter were used for a constant mass loading ratio of 0.3 in a jet with a Reynolds number of 20 000. The lateral mean velocity and number density profiles were expressed by best fitting functions and several invariable coefficients were found. The standard drag force coefficient C D for a single particle was applicable for a dilute particle cloud even in a non-uniform air velocity field. 相似文献