全文获取类型
收费全文 | 1892篇 |
免费 | 124篇 |
国内免费 | 2篇 |
专业分类
化学 | 1527篇 |
晶体学 | 3篇 |
力学 | 35篇 |
综合类 | 1篇 |
数学 | 204篇 |
物理学 | 248篇 |
出版年
2023年 | 28篇 |
2022年 | 22篇 |
2021年 | 34篇 |
2020年 | 52篇 |
2019年 | 44篇 |
2018年 | 26篇 |
2017年 | 18篇 |
2016年 | 89篇 |
2015年 | 80篇 |
2014年 | 77篇 |
2013年 | 86篇 |
2012年 | 118篇 |
2011年 | 119篇 |
2010年 | 82篇 |
2009年 | 62篇 |
2008年 | 109篇 |
2007年 | 107篇 |
2006年 | 107篇 |
2005年 | 101篇 |
2004年 | 90篇 |
2003年 | 61篇 |
2002年 | 44篇 |
2001年 | 38篇 |
2000年 | 28篇 |
1999年 | 34篇 |
1998年 | 25篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 15篇 |
1993年 | 18篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 16篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1936年 | 6篇 |
排序方式: 共有2018条查询结果,搜索用时 31 毫秒
1.
Sven Walter 《Acta Analytica》2005,20(3):32-47
Frank Jackson and Philip Pettit have defended a non-reductive account of causal relevance known as the ‘program explanation
account’. Allegedly, irreducible mental properties can be causally relevant in virtue of figuring in non-redundant program explanations which convey information not conveyed by explanations in terms of the physical properties that actually do the ‘causal work’.
I argue that none of the possible ways to spell out the intuitively plausible idea of a program explanation serves its purpose,
viz., defends non-reductive physicalism against Jaegwon Kim’s Causal Exclusion Argument according to which non-reductive physicalism is committed to epiphenomenalism because irreducible mental properties are ‘screened
off’ from causal relevance by their physical realizers. Jackson and Pettit’s most promising explication of a program explanation
appeals to the idea of invariance of effect under variation of realization, but I show that invariance of effect under variation of realization is neither necessary nor sufficient for causal relevance. 相似文献
2.
3.
Received December 31, 2001 / Published online May 21, 2002 相似文献
4.
Velislava A Ignatova Sven Van Den Berghe Steven Van Dyck Vladimir N Popok 《Microscopy and microanalysis》2006,12(5):432-437
The oxide scales of AISI 304 formed in boric acid solutions at 300 degrees C and pH = 4.5 have been studied using X-ray photoelectron spectroscopy (XPS) depth profiling. The present focus is depth profile quantification both in depth and chemical composition on a molecular level. The roughness of the samples is studied by atomic force microscopy before and after sputtering, and the erosion rate is determined by measuring the crater depth with a surface profilometer and vertical scanning interferometry. The resulting roughness (20-30 nm), being an order of magnitude lower than the crater depth (0.2-0.5 microm), allows layer-by-layer profiling, although the ion-induced effects result in an uncertainty of the depth calibration of a factor of 2. The XPS spectrum deconvolution and data evaluation applying target factor analysis allows chemical speciation on a molecular level. The elemental distribution as a function of the sputtering time is obtained, and the formation of two layers is observed-one hydroxide (mainly iron-nickel based) on top and a second one deeper, mainly consisting of iron-chromium oxides. 相似文献
5.
Christoph Elschenbroich Jrn Plackmeyer Klaus Harms Olaf Burghaus Jürgen Pebler 《无机化学与普通化学杂志》2006,632(5):819-827
Trovacene Chemistry. 13 [1] On Being Lead and Mislead in the Synthesis of Di([5]trovacenyl)ketone Di([5]trovacenyl)ketone ( 3¨ ) has been prepared from lithio‐[5]trovacene and dimethylcarbamoyl chloride and studied by X‐ray diffraction, cyclic voltammetry, magnetic susceptometry and EPR spectroscopy. Slight variation of the synthetic protocol affords an unusual trinuclear complex 5 ? that is also fully characterized. Spin‐spin exchange interaction is smaller in 3¨ than in 1,1‐di([5]trovacenylethene ( 2¨ ), which differs from 3¨ by a replacement of O for CH2. The novel trinuclear complex 5 ? , however, displays exchange coupling very similar to that observed in 1‐methoxy‐2,5,6‐tri([5]trovacenyl)benzene ( 7 ? ). In both cases, an unsymmetrical triangular arrangement of S = 1/2 centers is encountered. These findings are discussed in terms of the nature of the respective spacers. 相似文献
6.
Hai Huyen Dam Hans-Jürgen Zepernick Sven Nordholm Jörgen Nordberg 《Annals of Operations Research》2005,133(1-4):249-264
The performance of a code division multiple access system depends on the correlation properties of the employed spreading
code. Low cross-correlation values between spreading sequences are desired to suppress multiple access interference and to
improve bit error performance. An auto-correlation function with a distinct peak enables proper synchronization and suppresses
intersymbol interference. However, these requirements contradict each other and a trade-off needs to be established. In this
paper, a global two dimensional optimization method is proposed to minimize the out-of-phase average mean-square aperiodic
auto-correlation with average mean-square aperiodic cross-correlation being allowed to lie within a fixed region. This approach
is applied to design sets of complex spreading sequences. A design example is presented to illustrate the relation between
various correlation characteristics. The correlations of the obtained sets are compared with correlations of other known sequences. 相似文献
7.
8.
9.