全文获取类型
收费全文 | 609篇 |
免费 | 9篇 |
国内免费 | 9篇 |
专业分类
化学 | 330篇 |
晶体学 | 1篇 |
力学 | 16篇 |
数学 | 159篇 |
物理学 | 121篇 |
出版年
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 31篇 |
2012年 | 18篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 11篇 |
2008年 | 20篇 |
2007年 | 26篇 |
2006年 | 33篇 |
2005年 | 18篇 |
2004年 | 13篇 |
2003年 | 21篇 |
2002年 | 20篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 11篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1980年 | 16篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 20篇 |
1976年 | 12篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1970年 | 6篇 |
1933年 | 3篇 |
1891年 | 3篇 |
1890年 | 3篇 |
排序方式: 共有627条查询结果,搜索用时 15 毫秒
331.
332.
333.
Chris W. Patterson Harold W. Galbraith Burton J. Krohn William G. Harter 《Journal of Molecular Spectroscopy》1979,77(3):457-473
Clustering of tetrahedral levels is shown to occur in ν2 + ν3 type combination bands of spherical top molecules due to Coriolis and vibrational anharmonic interactions. Cluster correlation diagrams are shown for cases where the vibrational splitting is both large and small compared to the Coriolis splitting, and cluster approximations are given for both cases. 相似文献
334.
SSZ-60 is a new borosilicate zeolite that may be prepared using N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium or N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium as a structure directing agent; the framework of SSZ-60 was determined by the FOCUS Fourier recycling method, its structure refined in space group P21nm and found to possess a one-dimensional channel system with pores delimited by twelve-rings; the topological structure of SSZ-60 may be derived from a sigma-expansion of the framework of ZSM-23 (MTT). 相似文献
335.
Let be a non-trivial finite Galois extension of a field . In this paper we investigate the role that valuation-theoretic properties of play in determining the non-triviality of the relative Brauer group, , of over . In particular, we show that when is finitely generated of transcendence degree 1 over a -adic field and is a prime dividing , then the following conditions are equivalent: (i) the -primary component, , is non-trivial, (ii) is infinite, and (iii) there exists a valuation of trivial on such that divides the order of the decomposition group of at .
336.
The mechanism and kinetics of the reaction of O(3P) atoms with propane were investigated using molecular modulation spectroscopy, with the O(3P) atoms being generated by the Hg photosensitized decomposition of N2O. The absorption spectrum of the X2II3/2 state of OH was observed in the ultraviolet between 307 and 309 nm, and it was confirmed that OH was the product of the O(3P) reaction with propane. The rate constants for the reactions of O(3P) and OH with propane were determined to be 3.9±0.7±1010 and 1.19±0.05±1012 cm3/mole·sec, respectively, at T=56±5°C. 相似文献
337.
338.
Organizations and Complexity: Searching for the Edge of Chaos 总被引:2,自引:0,他引:2
Traditional organizational theory advocates increased differentiation and horizontal integration for organizations in unstable environments or with uncertain technologies. This paper seeks to develop a better understanding of the relationship of group structure and the level of interdependency between individuals on group performance under various task complexities. Complexity theory in general, and NK models in particular, are introduced as theoretical frameworks that offer an explanation for group performance. Simulation models are developed, based on the communication network research of Bavelas (1948) and Leavitt (1952), to explore the effects of decentralization and interdependence. The simulation model developed here shows general consistency with previous human subject experiments. However, contrary to predictions, not all decentralized group structures perform well when undertaking complex task assignments. Structures that are highly connected (actors communicating with all others) perform much worse than those with a lower level of connection. Further experiments varying both the number of actors and the degree of interdependence between them find evidence of the edge of chaos. This research advances our understanding of organizations beyond earlier models by suggesting that there is an optimal range of interconnectedness between actors or tasks that explains the variation in performance. An intriguing result is that this optimal level of interdependence is fairly low, regardless of the size of the group. 相似文献
339.
We have examined the dependence of the chemical activity of a platinum/gold alloy on surface morphology and surface composition. Measurements of surface composition by Auger spectroscopy and surface chemical activity by CO flash desorption indicate that sample morphology strongly affects both the surface composition and surface chemical behavior. These results raise questions about the comparability of data obtained on differently prepared polycrystalline alloy samples. 相似文献
340.