全文获取类型
收费全文 | 2074篇 |
免费 | 47篇 |
国内免费 | 3篇 |
专业分类
化学 | 1158篇 |
晶体学 | 11篇 |
力学 | 55篇 |
数学 | 292篇 |
物理学 | 608篇 |
出版年
2021年 | 13篇 |
2020年 | 11篇 |
2019年 | 23篇 |
2018年 | 20篇 |
2017年 | 11篇 |
2016年 | 40篇 |
2015年 | 28篇 |
2014年 | 35篇 |
2013年 | 87篇 |
2012年 | 77篇 |
2011年 | 71篇 |
2010年 | 34篇 |
2009年 | 24篇 |
2008年 | 74篇 |
2007年 | 74篇 |
2006年 | 67篇 |
2005年 | 86篇 |
2004年 | 71篇 |
2003年 | 78篇 |
2002年 | 64篇 |
2001年 | 60篇 |
2000年 | 60篇 |
1999年 | 48篇 |
1998年 | 22篇 |
1997年 | 41篇 |
1996年 | 49篇 |
1995年 | 34篇 |
1994年 | 28篇 |
1993年 | 33篇 |
1992年 | 38篇 |
1991年 | 29篇 |
1990年 | 51篇 |
1989年 | 39篇 |
1988年 | 39篇 |
1987年 | 26篇 |
1986年 | 30篇 |
1985年 | 42篇 |
1984年 | 38篇 |
1983年 | 31篇 |
1982年 | 36篇 |
1981年 | 28篇 |
1980年 | 28篇 |
1979年 | 21篇 |
1978年 | 27篇 |
1977年 | 29篇 |
1976年 | 20篇 |
1975年 | 26篇 |
1974年 | 21篇 |
1973年 | 31篇 |
1971年 | 12篇 |
排序方式: 共有2124条查询结果,搜索用时 31 毫秒
991.
S. H. Hall 《Contemporary Physics》2013,54(6):430-439
992.
Nanostructured alloys are efficient catalysts for mediating renewable energy storage and recovery reactions. The morphology and composition of an alloy can change during catalysis; particularly for potentials more oxidizing than the reversible hydrogen electrode. The formation of noble-metal shells covering an alloy core, or bi-continuous nanoporosity, is a common way an alloy can evolve by a corrosion mediated process. Recently, it was found that alloys can reconstruct within the bulk and form an ordered intermetallic material with different crystal structures and compositions than the starting material during corrosion. This review will discuss the different pathways alloys can be altered by electrochemistry. We will discuss the mechanisms which cover known structural changes and the more recently discovered process involving electrochemically driven incongruent phase transformations. Insights into the transformation of alloy materials are important for understanding how to prepare catalysts with improved electrochemical stability, and for synthesizing materials. 相似文献
993.
994.
We develop the theory set out in Part 1 [R.R. Hall, Large spaces between the zeros of the Riemann zeta-function and random matrix theory, J. Number Theory 109 (2004) 240–265] and in particular provide a lower bound (and almost sure evaluation) for Λ(7). The square of this number is rational, as were the previous values, but still rather surprizing. 相似文献
995.
996.
997.
998.
A. J. Hall K. Schwertassek G. Garkuscha K. M. Markuse A. W. Ssurowaja A. P. Sakonschtschikow D. I. Galperin D. I. Tumarkin J. Barritt H. H. Bowen F. L. Goodall A. Whitehead H. R. Hirst A. T. King M. Harris A. L. Smith T. A. Schmelewa und R. Hart 《Fresenius' Journal of Analytical Chemistry》1940,120(5-6):216-220
Ohne Zusammenfassung 相似文献
999.
1000.
Joshua A. Krakos Qiqi Wang Steven R. Hall David L. Darmofal 《Journal of computational physics》2012,231(8):3228-3245
Many unsteady problems equilibrate to periodic behavior. For these problems the sensitivity of periodic outputs to system parameters are often desired, and must be estimated from a finite time span or frequency domain calculation. Sensitivities computed in the time domain over a finite time span can take excessive time to converge, or fail altogether to converge to the periodic value. Additionally, finite span outputs can exhibit local extrema in parameter space which the periodic outputs they approximate do not, hindering their use in optimization. We derive a theoretical basis for this error and demonstrate it using two examples, a van der Pol oscillator and vortex shedding from a low Reynolds number airfoil. We show that output windowing enables the accurate computation of periodic output sensitivities and may allow for decreased simulation time to compute both time-averaged outputs and sensitivities. We classify two distinct window types: long-time, over a large, not necessarily integer number of periods; and short-time, over a small, integer number of periods. Finally, from these two classes we investigate several examples of window shape and demonstrate their convergence with window size and error in the period approximation, respectively. 相似文献