全文获取类型
收费全文 | 19531篇 |
免费 | 583篇 |
国内免费 | 107篇 |
专业分类
化学 | 12540篇 |
晶体学 | 112篇 |
力学 | 402篇 |
综合类 | 2篇 |
数学 | 3894篇 |
物理学 | 3271篇 |
出版年
2023年 | 123篇 |
2022年 | 311篇 |
2021年 | 419篇 |
2020年 | 382篇 |
2019年 | 356篇 |
2018年 | 741篇 |
2017年 | 531篇 |
2016年 | 657篇 |
2015年 | 525篇 |
2014年 | 584篇 |
2013年 | 1151篇 |
2012年 | 1186篇 |
2011年 | 1250篇 |
2010年 | 801篇 |
2009年 | 771篇 |
2008年 | 1107篇 |
2007年 | 1068篇 |
2006年 | 1002篇 |
2005年 | 926篇 |
2004年 | 720篇 |
2003年 | 647篇 |
2002年 | 573篇 |
2001年 | 332篇 |
2000年 | 378篇 |
1999年 | 239篇 |
1998年 | 185篇 |
1997年 | 193篇 |
1996年 | 222篇 |
1995年 | 155篇 |
1994年 | 169篇 |
1993年 | 150篇 |
1992年 | 135篇 |
1991年 | 120篇 |
1990年 | 131篇 |
1989年 | 113篇 |
1988年 | 86篇 |
1987年 | 91篇 |
1986年 | 92篇 |
1985年 | 108篇 |
1984年 | 128篇 |
1983年 | 93篇 |
1982年 | 103篇 |
1981年 | 102篇 |
1980年 | 80篇 |
1979年 | 62篇 |
1978年 | 81篇 |
1977年 | 66篇 |
1976年 | 68篇 |
1975年 | 61篇 |
1973年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The convergence of iterative based domain decomposition methods is linked with the absorbing boundary conditions defined on the interface between the sub-domains. For linear elasticity problems, the optimal absorbing boundary conditions are associated with non-local Dirichlet-to-Neumann maps. Most of the methods to approximate these non-local maps are based on a continuous analysis. In this paper, an original algebraic technique based on the computation of local Dirichlet-to-Neumann maps is investigated. Numerical experiments are presented for linear elasticity problems with extreme contrasts in the coefficients. 相似文献
62.
Roland Omnès 《Foundations of Physics》1995,25(4):605-629
A rather recent interpretation of quantum mechanics, known under the various names of consistent histories, decohering histories, or logical interpretation, has brought interpretation into a standard deductive theory and is now investigated in many places. A key difference with the Copenhagen interpretation is the status of classical physics, now derived completely from quantum principles in both its dynamical and logical aspects. After describing briefly this new interpretation in its essentials, leaving aside technical details, it is shown how its consequences in epistemology differ drastically from the familiar outcomes of the Copenhagen interpretation, leading in particular to a well-defined theory of knowledge. Some more speculative philosophical consequences associated with the unsolved problem of actuality are also mentioned. 相似文献
63.
János Komlós 《Order》1990,7(2):107-113
Using Ramsey theory, we establish the following pigeon-hole type principle: From a large number of random variables (functions, vectors, etc.) one can always select two, X and Y, such that P(X < Y) 1/2. We apply the principle for a poset problem. 相似文献
64.
65.
We give an asymptotically sharp estimate for the error term of the maximum number of unit distances determined byn points in
d, d4. We also give asymptotically tight upper bounds on the total number of occurrences of the favourite distances fromn points in
d, d4. Related results are proved for distances determined byn disjoint compact convex sets in 2.At the time this paper was written, both authors were visiting the Technion — Israel Institute of Technology. 相似文献
66.
In this paper the distribution of the zeros of the error function for bestL
1-approximation by rational functions fromR
n,m
is considered. It is shown that the maximal distance between such zeros isO(1/(n–m)), ifn > m.Communicated by Edward B. Saff. 相似文献
67.
The reaction between thiocarbamate herbicides and 2,6-dichlorobenzoquinone-N-chloroimine or 2,6-dibromobenzoquinone-N-chloroimine is suitable for the detection of these herbicides on thin-layer plates with high sensitivity. The reactions were followed by infrared, nuclear magnetic resonance and mass spectrometry. We have established the formation of 2,6-dichlorobenzoquinone-S-alkyl sulphenylimines. In the case of the bromo-derivative, halogen exchange and substitution on the quinone ring took place simultaneously leading to the formation of mixed halogenated 2,6-dihalo- and, in addition, 2,3,6-trihalobenzoquinone-S-alkyl sulphenylimines. The final product of the detection reaction, i.e. 2,6-dichlorobenzoquinone-S-alkyl sulphenylimine was reacted with 2,6-dibromobenzoquinone-N-chloroimine where 2,6-dichloro-3-bromobenzoquinone-S-alkyl sulphenylimine formed as a consequence of the looser bromine-carbon linkage on the 2 and 6 positions of the quinone ring. 相似文献
68.
69.
Antolín R Borge G Posada T Raposo JC Seara I Etxebarria N 《Journal of AOAC International》2004,87(5):1218-1223
A validation study was carried out in order to evaluate the efficiency of inductively coupled plasma-optical emission spectrometry (ICP-OES) for the analysis of minor elements (manganese, chromium, copper, iron, and titanium) in aluminium alloys. Aluminium casting samples were obtained by adding compressed powder compacts of each alloying element and aluminium (minitablets) to aluminum baths in a laboratory crucible furnace. Digestion of solid samples was performed using concentrated HCI and H202 35% (v/v) previous to analysis by ICP-OES without any matrix separation. This solution-based method was validated considering direct current arc spectrometry as the reference method based on direct analysis without any pretreatment of the solid samples considered. Univariate statistical procedures were carried out, for which precision <3% and trueness of the analytical results were taken into account. 相似文献
70.
J. Heidberg E. Kampshoff M. Kandel R. Kühnemuth D. Meine O. Schönekäs M. Suhren H. Weiss 《Reaction Kinetics and Catalysis Letters》1993,50(1-2):123-129
Polarized infrared spectra of adsorbates on NaCl(100) and MgO(100) single crystal cleavage planes reveal Davydov splittings, structures with adsorbate orientations and/or 2D-phase transitions, in concert with diffraction studies. CO2 on NaCl shows the sharpest adsorbate spectra known (
). 相似文献