全文获取类型
收费全文 | 1575篇 |
免费 | 30篇 |
国内免费 | 6篇 |
专业分类
化学 | 981篇 |
晶体学 | 8篇 |
力学 | 62篇 |
数学 | 90篇 |
物理学 | 470篇 |
出版年
2020年 | 20篇 |
2019年 | 14篇 |
2016年 | 21篇 |
2015年 | 17篇 |
2014年 | 32篇 |
2013年 | 66篇 |
2012年 | 43篇 |
2011年 | 69篇 |
2010年 | 50篇 |
2009年 | 36篇 |
2008年 | 60篇 |
2007年 | 42篇 |
2006年 | 54篇 |
2005年 | 29篇 |
2004年 | 39篇 |
2003年 | 23篇 |
2002年 | 54篇 |
2001年 | 42篇 |
2000年 | 38篇 |
1999年 | 42篇 |
1998年 | 26篇 |
1997年 | 26篇 |
1996年 | 34篇 |
1995年 | 35篇 |
1994年 | 27篇 |
1993年 | 32篇 |
1992年 | 27篇 |
1991年 | 30篇 |
1990年 | 22篇 |
1989年 | 24篇 |
1988年 | 20篇 |
1987年 | 27篇 |
1986年 | 14篇 |
1985年 | 27篇 |
1984年 | 25篇 |
1983年 | 25篇 |
1982年 | 20篇 |
1981年 | 24篇 |
1980年 | 31篇 |
1979年 | 22篇 |
1978年 | 17篇 |
1977年 | 16篇 |
1976年 | 19篇 |
1975年 | 15篇 |
1974年 | 20篇 |
1973年 | 23篇 |
1970年 | 19篇 |
1969年 | 18篇 |
1968年 | 14篇 |
1967年 | 16篇 |
排序方式: 共有1611条查询结果,搜索用时 204 毫秒
11.
12.
13.
14.
The potential of a package of quantum-chemical software programs for exploring physicochemical problems pertaining to polyatomic organic molecules is highlighted. The results of investigation into the spectral, luminescent, and photochemical properties of molecules are discussed. The necessity of development of target-oriented models for studying the problems of physics and chemistry of molecules is emphasized. 相似文献
15.
16.
17.
The chromatographic separation properties of long, thin adsorption tubes enable substance-specific quantitative enrichment and reduction to be achieved when sampling and thermal desorption are carried out in the same flow direction. The specific retention volumes, and also the breakthrough and peak end volumes, of 69 compounds in the boiling range between-164 and 126°C and of a relative molecular mass between 16 and 119 were determined at temperatures between 30 and 130°C: normal alkanes, isoalkanes, cycloalkanes, alkenes, polyenes, alkynes, aromatics, ethers, alcohols, aldehydes, ketones, carboxylic acids and their esters, nitroalkanes, O-heterocycles, S-heterocycles, chloroalkanes, water, nitrogen monoxide, nitrogen dioxide, carbon dioxide, and sulfur dioxide. The correlation between adsorbent temperature and specific retention volume of these components, presented in the form of diagrams, permits the required quantity of adsorbent to be determined for a given sample volume. Contrary to literature sources, even extremely volatile compounds such as propane, propene, methanol, formaldehyde, formic acid, and chloromethane can be quantitatively retained on Tenax provided the operating conditions are appropriately selected. 相似文献
18.
Tahallah N Pinkse M Maier CS Heck AJ 《Rapid communications in mass spectrometry : RCM》2001,15(8):596-601
The effect of elevating the pressure in the interface region of an electrospray ionization orthogonal time-of-flight mass spectrometer on the ion intensity of different noncovalent protein assemblies has been investigated. Elevating the pressure in the interface region generally led to an enhanced detection of high m/z ions. The optimum pressure was found to be dependent on the m/z value of the ions. This pressure effect should be carefully addressed when relating ion abundance in the mass spectra to solution phase abundance of noncovalent protein assemblies. 相似文献
19.
Indications for the occurrence of nitric oxide synthases in Dictyostelium, Neurospora, Phycomyces and the leguminous plant Mucuna hassjoo as well as a physiological role of nitric oxide in Neurospora crassa are demonstrated. An exogenous nitric oxide donor, sodium nitroprus-side, inhibited light-stimulated conidiation in N. crassa. Specific inhibitors of nitric oxide synthase, like the arginine derivatives NG-nitro-L-arginine (L-NA) and NG-nitro-L-arginine-methyl ester (L-NAME), enhanced conidiation in darkness and in the light, whereas the stereo-isomer D-NAME was inactive. This communication reports to our knowledge the first time the presence of enzymatic activity of nitric oxide synthase in fungi and a higher plant and an effect of nitric oxide in fungal photophysiology. 相似文献
20.
I. V. Sokolova O. N. Chaikovskaya V. A. Svetlichnyi R. T. Kuznetsova T. N. Kopylova G. V. Maier E. A. Sosnin E. A. Lipatov V. F. Tarasenko 《High Energy Chemistry》2002,36(4):272-275
The photolysis of aqueous solutions of two widespread environmental organic ecotoxicants—phenol and 4-chlorophenol—on excitation by UV radiation from a KrCl exciplex laser and a glow-discharge KrCl excilplex lamp was studied. The irradiated solutions were studied by spectroscopic techniques. The laser and lamp photolyses were compared. 相似文献