全文获取类型
收费全文 | 1178篇 |
免费 | 45篇 |
国内免费 | 5篇 |
专业分类
化学 | 758篇 |
晶体学 | 10篇 |
力学 | 33篇 |
数学 | 168篇 |
物理学 | 259篇 |
出版年
2023年 | 10篇 |
2022年 | 26篇 |
2021年 | 23篇 |
2020年 | 39篇 |
2019年 | 33篇 |
2018年 | 37篇 |
2017年 | 35篇 |
2016年 | 44篇 |
2015年 | 36篇 |
2014年 | 38篇 |
2013年 | 84篇 |
2012年 | 77篇 |
2011年 | 92篇 |
2010年 | 50篇 |
2009年 | 46篇 |
2008年 | 67篇 |
2007年 | 62篇 |
2006年 | 47篇 |
2005年 | 48篇 |
2004年 | 37篇 |
2003年 | 19篇 |
2002年 | 15篇 |
2001年 | 16篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1994年 | 7篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 19篇 |
1976年 | 16篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 5篇 |
排序方式: 共有1228条查询结果,搜索用时 46 毫秒
71.
The paper reports a structural study of some memory and threshold chalcogenides in terms of coordination numberC, defined byC=8−N, and is the average coordination number for covalently bonded materials. The average number of nearest neighbours surrounding
a central atom, obtained for As-Ge-Te (memory) and Se-Ge-Te (threshold) systems have been used to estimate the cohesive energies,
assuming simple additivity of bond energies. The bonding pattern so obtained, explains certain properties of these glasses. 相似文献
72.
Electrochemical oxidation of uric acid in phosphate-containing supporting electrolytes between pH 3–9 at a reticulated vitreous carbon electrode in a thin-layer spectroelectrochemical cell leads to formation of U.V.-absorbing intermediate species. Electrochemical reduction of the intermediate-containing solution leads to the partial regeneration of uric acid. This behavior provides compelling evidence that an imine-alcohol is one of the U.V.-absorbing intermediate species since only this compound may be expected to be reduced to a species which can regenerate uric acid. 相似文献
73.
Polarographic reduction of 2-amino-4-aryl-5-phenylazothiazoles takes place in a single 2-electron transfer, giving a diffusion-controlled irreversible wave in the pH range 2.0-10.0. Substituents in the 4-position of the thiazole moiety shift the half-wave potential through conjugation of the system. A correlation of E(sol;1 2 ) with the Brown and Hammett substituent constant has also been established. 相似文献
74.
75.
The generation of a circular fringe system of Newton rings' type with dark fringe at the centre is described. Such fringes are localized at infinity and are produced by a pair of longitudinally displaced mutually complimentary diffusers. Experimental results under various displacement configurations have been presented. 相似文献
76.
S. K. Goyal 《The Journal of the Operational Research Society》1973,24(3):391-401
A first attempt at applying OR techniques and approaches in a fine art printing firm manufacturing greeting cards is reported in this paper. The problem of economic production of cards is formulated and four related methods are presented, the fourth being a probabilistic model with possibly wider applications in the fashion industry 相似文献
77.
S.K. Goyal 《European Journal of Operational Research》1980,4(3):185-188
The search procedure developed in this paper is typically applicable in those inventory systems where a product is packaged immediately after manufacture into a number of container sizes and the packaged items of similar sizes are sold under more than one brand name. The most common example of such items can be seen in supermarkets where grocery items of identical characteristics (produced by the same manufacture) are available under the supermarket's own brand and under the manufacturer's nationally advertised brand. An example has been solved to illustrate the method. 相似文献
78.
79.
The radical reactions of a series of bromides 9a-c and selenides 12-15 have been investigated to determine the factors that are important for a successful radical-mediated 1,2-imino migration. 相似文献
80.
Karajanagi SS Vertegel AA Kane RS Dordick JS 《Langmuir : the ACS journal of surfaces and colloids》2004,20(26):11594-11599
We have examined the structure and function of two enzymes, alpha-chymotrypsin (CT) and soybean peroxidase (SBP), adsorbed onto single-walled carbon nanotubes (SWNTs). SBP retained up to 30% of its native activity upon adsorption, while the adsorbed CT retained only 1% of its native activity. Analysis of the secondary structure of the proteins via FT-IR spectroscopy revealed that both enzymes undergo structural changes upon adsorption, with substantial secondary structural perturbation observed for CT. Consistent with these results, AFM images of the adsorbed enzymes indicated that SBP retains its native three-dimensional shape while CT appears to unfold on the SWNT surface. This study represents the first in depth investigation of protein structure and function on carbon nanotubes, which is critical in designing optimal carbon nanotube-protein conjugates. 相似文献