全文获取类型
收费全文 | 934篇 |
免费 | 16篇 |
国内免费 | 5篇 |
专业分类
化学 | 480篇 |
晶体学 | 7篇 |
力学 | 23篇 |
数学 | 127篇 |
物理学 | 318篇 |
出版年
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 5篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 18篇 |
2017年 | 21篇 |
2016年 | 25篇 |
2015年 | 25篇 |
2014年 | 30篇 |
2013年 | 51篇 |
2012年 | 46篇 |
2011年 | 49篇 |
2010年 | 42篇 |
2009年 | 41篇 |
2008年 | 57篇 |
2007年 | 37篇 |
2006年 | 46篇 |
2005年 | 36篇 |
2004年 | 30篇 |
2003年 | 22篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 18篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 20篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 15篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1957年 | 4篇 |
1936年 | 4篇 |
排序方式: 共有955条查询结果,搜索用时 60 毫秒
31.
32.
33.
D. Ghosh J. Roy M. Basu A. Bhattacharjee T. Guhathakurta K. Sengupta 《Czechoslovak Journal of Physics》1982,32(11):1221-1224
This paper presents an extensive study on the dependence of the mean number of the fast fragment of the target nucleus n
g on the incident beam energy in proton-nucleus interaction in emulsion in the range 6·2E
0400 GeV/c. It has been observed that n
g decreases in the range 6·2E
0200 GeV/c, then increases and attains an approximately steady value up to 400 GeV/c. It is very difficult to explain this behaviour with the help of the existing nuclear production models.The author would like to thank Prof A. J. Herz (CERN), Prof. K. D. Tolostov (Dubna, U.S.S.R.), Prof. P. L. Jain (State University of New York, U.S.A.), Prof. G. Giacomelly (Italy) for kindly supplying the exposed emulsion plates. 相似文献
34.
An improved and eco‐friendly procedure has been developed to generate mesoporous silica‐supported palladium nanoparticles (SiO2@PdNP) that could be used as a sustainable heterogeneous Pd catalyst for phosphine‐free Suzuki–Miyaura and Heck coupling reactions with excellent turnover number and turnover frequency. The presence of Pd on the silica surface was detected by X‐ray diffraction and the structural morphology of SiO2@PdNP was obtained by transmission electron microscopy. The heterogeneous catalytic system is recyclable and leaching of the metal after the reaction is not apparently observed. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
35.
Selvan Ravindran Sudipta Basu Santosh Kapil Kumar Gorti Prashant Surve Navya Sloka 《Biomedical chromatography : BMC》2013,27(5):575-582
The sulfonylurea urea drug glyburide (glibenclamide) is widely used for the treatment of diabetes milletus and gestational diabetes. In previous studies monohydroxylated metabolites were identified and characterized for glyburide in different species, but the metabolite owing to the loss of cyclohexyl ring was identified only in mouse. Glyburide upon incubation with hepatic microsomes resulted in 10 metabolites for human. The current study identifies new metabolites of glyburide along with the hydroxylated metabolites that were reported earlier. The newly identified drug metabolites are dihydroxylated metabolites, a metabolite owing to the loss of cyclohexyl ring and one owing to hydroxylation with dehydrogenation. Among the 10 identified metabolites, there were six monohydroxylated metabolites, one dihydroxylated metabolite, two metabolites owing to hydroxylation and dehydrogenation, and one metabolite owing to the loss of cyclohexyl ring. New metabolites of glyburide were identified and characterized using liquid chromatography–diode array detector–quadruple‐ion trap–mass spectrometry/mass spectrometry (LC‐DAD‐Q‐TRAP‐MS/MS). An enhanced mass scan–enhanced product ion scan with information‐dependent acquisition mode in a Q‐TRAP‐MS/MS system was used to characterize the metabolites. Liquid chromatography with diode array detection was used as a complimentary technique to confirm and identify the metabolites. Metabolites formed in higher amounts were detected in both diode array detection and mass spectrometry detection. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
36.
37.
38.
Ester Abtew Abraham J. Domb Arijit Basu 《Journal of polymer science. Part A, Polymer chemistry》2017,55(16):2657-2662
We report on the synthesis of polypeptides with saccharide side chains starting from d ‐glucosaminic acid. The hydroxyl groups were first protected by benzylation, followed by N‐carboxyanhydride formation, which was polymerized by ring opening to form a high molecular weight polyamide. De‐protection of the benzyl groups yields a polypeptide with fully de‐protected saccharide side chains. The resulting new non‐ionic, water soluble, and optically active polymers possessing the properties of both peptides and saccharides have potential use as scaffolds for tissue engineering and drug carriers. The method described here may be extended to any saccharide α‐amino acid. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2657–2662 相似文献
39.
This paper provides a new framework for the derivation and estimation of consumption and equity premium functions. Applying duality in a dynamic context, we show that equity premium and consumption functions can be easily obtained from the indirect utility function. Our new framework, therefore, does not require explicit specification of underlying consumer preferences. Using aggregate US data (1929–2000) we estimate the consumption and equity premium functions using a nonparametric technique. We find that the model does well in explaining the observed smooth consumption patterns and does reasonably well in explaining the high mean and volatility of equity premia. 相似文献
40.