全文获取类型
收费全文 | 6763篇 |
免费 | 347篇 |
国内免费 | 86篇 |
专业分类
化学 | 4724篇 |
晶体学 | 54篇 |
力学 | 139篇 |
综合类 | 5篇 |
数学 | 1212篇 |
物理学 | 1062篇 |
出版年
2023年 | 53篇 |
2022年 | 98篇 |
2021年 | 176篇 |
2020年 | 137篇 |
2019年 | 152篇 |
2018年 | 134篇 |
2017年 | 121篇 |
2016年 | 292篇 |
2015年 | 243篇 |
2014年 | 239篇 |
2013年 | 531篇 |
2012年 | 530篇 |
2011年 | 576篇 |
2010年 | 325篇 |
2009年 | 272篇 |
2008年 | 414篇 |
2007年 | 391篇 |
2006年 | 330篇 |
2005年 | 365篇 |
2004年 | 255篇 |
2003年 | 249篇 |
2002年 | 215篇 |
2001年 | 101篇 |
2000年 | 95篇 |
1999年 | 56篇 |
1998年 | 67篇 |
1997年 | 55篇 |
1996年 | 85篇 |
1995年 | 44篇 |
1994年 | 47篇 |
1993年 | 57篇 |
1992年 | 39篇 |
1991年 | 39篇 |
1990年 | 41篇 |
1989年 | 35篇 |
1988年 | 30篇 |
1987年 | 33篇 |
1986年 | 21篇 |
1985年 | 41篇 |
1984年 | 31篇 |
1983年 | 22篇 |
1982年 | 24篇 |
1981年 | 24篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 7篇 |
1974年 | 8篇 |
1973年 | 4篇 |
排序方式: 共有7196条查询结果,搜索用时 578 毫秒
31.
Using the Q representation, we study the disagreement between quantum optical formalism and local realism and we show that the phenomenon of enhancement, first revealed by the local realist analysis, could receive a simple explanation if we use this particular version of the quantum formalism. Nevertheless, some fundamental difficulties remain. 相似文献
32.
33.
We derive the action of 2D gravity from the two-cocycle of the Virasoro group by using a previously introduced method for constructing a dynamical system from a Lie group. A natural construction and explanation of the hidden SL(2,
)-Kac-Moody symmetry, of general applicability, is provided. We also show how the proper quantization goes beyond the ordinary co-adjoint orbit method, and the possible connection with the Poisson-Lie groups. 相似文献
34.
Stereoselectivity in the intermolecular Pauson-Khand reaction of electron-deficient terminal alkynes
A family of terminal alkyne dicobalthexacarbonyl complexes bearing groups with a range of electron-withdrawing abilities has been synthesized. After submitting these complexes to the intermolecular Pauson-Khand reaction with norbornadiene, electron-deficient substrates afforded up to 26% of the unexpected endo-cyclopentenone. 相似文献
35.
A linear inequality system with infinitely many constraints is polynomial (analytical) if its index set is a compact interval
of the real line and all its coefficients are polynomial (analytical, respectively) functions of the index on this interval.
This paper provides an example of analytical system whose solution set cannot be the solution set of any polynomial system.
Research supported by DGES of Spain and FEDER of UE, Grant BFM2002-04114-C02-01.
Research supported by CONACyT of Mexico, Grant 130036.
Research partially supported by CONACyT of Mexico, Grant 44003. 相似文献
36.
Miguel A. Arcones 《Annals of the Institute of Statistical Mathematics》1998,50(1):87-117
We consider exact weak and strong Bahadur-Kiefer representations of the least absolute deviation estimator for the linear regression model. The precise behavior of these representations is obtained under minimal conditions. 相似文献
37.
38.
Large-scale production of cellulose-binding domains. Adsorption studies using CBD-FITC conjugates 总被引:1,自引:0,他引:1
Ricardo Pinto Joana Carvalho Manuel Mota Miguel Gama 《Cellulose (London, England)》2006,13(5):557-569
A method for the gram-scale production of cellulose-binding domains (CBD) through the proteolytic digestion of a commercial enzymatic preparation (Celluclast) was developed. The CBD obtained, isolated from Trichoderma reesei cellobiohydrolase I, is highly pure and heavily glycosylated. The purified peptide has a molecular weight of 8.43 kDa, comprising the binding module, a part of the linker, and about 30% glycosidic moiety. Its properties may thus be different from recombinant ones expressed in bacteria. CBD-fluorescein isothiocyanate conjugates were used to study the CBD-cellulose interaction. The presence of fluorescent peptides adsorbed on crystalline and amorphous cellulose fibers suggests that amorphous regions have a higher concentration of binding sites. The adsorption is reversible, but desorption is a very slow process. 相似文献
39.
The algebras of Kleinian type are finite-dimensional semisimple rational algebras A such that the group of units of an order in A is commensurable with a direct product of Kleinian groups. We classify the Schur algebras of Kleinian type and the group algebras of Kleinian type. As an application, we characterize the group rings RG, with R an order in a number field and G a finite group, such that the group of units of RG is virtually a direct product of free-by-free groups. 相似文献
40.
The main goal of this paper is to prove analytically the existence of strange attractors in a family of vector fields consisting of two Brusselators linearly coupled by diffusion. We will show that such a family contains a generic unfolding of a 4-dimensional nilpotent singularity of codimension 4. On the other hand, we will prove that in any generic unfolding Xμ of an n-dimensional nilpotent singularity of codimension n there are bifurcation curves of (n−1)-dimensional nilpotent singularities of codimension n−1 which are in turn generically unfolded by Xμ. Arguments conclude recalling that any generic unfolding of the 3-dimensional nilpotent singularity of codimension 3 exhibits strange attractors. 相似文献