全文获取类型
收费全文 | 9127篇 |
免费 | 385篇 |
国内免费 | 23篇 |
专业分类
化学 | 6223篇 |
晶体学 | 55篇 |
力学 | 210篇 |
数学 | 1342篇 |
物理学 | 1705篇 |
出版年
2023年 | 69篇 |
2022年 | 120篇 |
2021年 | 174篇 |
2020年 | 151篇 |
2019年 | 157篇 |
2018年 | 158篇 |
2017年 | 171篇 |
2016年 | 356篇 |
2015年 | 256篇 |
2014年 | 310篇 |
2013年 | 572篇 |
2012年 | 659篇 |
2011年 | 740篇 |
2010年 | 395篇 |
2009年 | 356篇 |
2008年 | 587篇 |
2007年 | 608篇 |
2006年 | 496篇 |
2005年 | 511篇 |
2004年 | 411篇 |
2003年 | 352篇 |
2002年 | 291篇 |
2001年 | 183篇 |
2000年 | 162篇 |
1999年 | 109篇 |
1998年 | 84篇 |
1997年 | 66篇 |
1996年 | 114篇 |
1995年 | 85篇 |
1994年 | 84篇 |
1993年 | 66篇 |
1992年 | 61篇 |
1991年 | 50篇 |
1990年 | 40篇 |
1989年 | 41篇 |
1988年 | 36篇 |
1987年 | 32篇 |
1986年 | 30篇 |
1985年 | 42篇 |
1984年 | 54篇 |
1983年 | 28篇 |
1982年 | 42篇 |
1981年 | 39篇 |
1980年 | 29篇 |
1979年 | 28篇 |
1978年 | 25篇 |
1977年 | 14篇 |
1976年 | 10篇 |
1975年 | 17篇 |
1974年 | 11篇 |
排序方式: 共有9535条查询结果,搜索用时 15 毫秒
161.
A completely automated method to determine the most common parameters in cured meat products is proposed. The approach to full automation is based on the coupling of a robotic station for development of preliminary operations (namely weighing of the sample, grinding, leaching, filtration and transport to the aspiration zone) and a continuous unsegmented manifold for derivatisation and spectrophotometric monitoring of the reaction coloured products. This assembly works in an unattended fashion thus eliminating the bottleneck produced by the determination of these parameters in routine laboratories. The good agreement between results obtained by the proposed method and those from conventional methods for target analytes confirms its excellent performance and usefulness. 相似文献
162.
163.
Extending previous work on the geometric characterization of separability in the autonomous case, necessary and sufficient conditions are established for the complete separability of a system of time-dependent second-order ordinary differential equations. In deriving this result, extensive use is made of the theory of derivations of scalar and vector-valued forms along the projection :J
1
EE of the first jet bundle of a fibre bundleE . Two illustrative examples are discussed, which fully demonstrate all aspects of the constructive nature of the theory. 相似文献
164.
165.
166.
Lucifer yellow and lissamine rhodamine sulfonyl hydrazine were used as the donor and the receptor, respectively, for Förster energy transfer measurements to determine the location of the subunit in the native Na,K-ATPase from pig kidney. It was found that (1) the subunits are located in one functional complex, i.e., the dimer ()2 appears to be the functional complex of Na,K-ATPase, and (2) the subunits in the functional enzyme complex in the membrane are not located next to each other but are rather well separated. The distance between fluorophores covalently attached to the subunits was found to be 5.3 nm. 相似文献
167.
Roberto Pignoni 《Geometriae Dedicata》1993,45(3):263-287
We study some global projective properties of real plane curves with cusps, beaks and normal crossings. Starting from Fabricius-Bjerre's formula on the singularities of a curve in an affine plane, we describe its extension to a projective setting. Given a curve RP2, by fixing a base point we associate some indices to its singularities and double tangents. We prove two global relations linking these entities together. 相似文献
168.
We consider overdetermined nonlinear systems of equationsF(x)=0, whereF:
n
m
,mn. For this type of systems we define weighted least square distance (WLSD) solutions, which represent an alternative to classical least squares solutions and to other solutions based on residual normas. We introduce a generalization of the classical method of Cimmino for linear systems and we prove local convergence results. We introduce a practical strategy for improving the global convergence properties of the method. Finally, numerical experiments are presented.Work supported by FAPESP (Grant 90/3724/6), FINEP, CNPq and FAEP-UNICAMP. 相似文献
169.
Detlev Buchholz Sergio Doplicher Roberto Longo John E. Roberts 《Communications in Mathematical Physics》1993,155(1):123-134
We characterize the automorphisms of aC
*-algebra which extend to automorphisms of the crossed product by a compact group dual. The case where the inclusion is equipped with a group of automorphisms commuting with the dual action is also treated. These results are applied to the analysis of broken gauge symmetries in Quantum Field Theory to draw conclusions on the structure of the degenerate vacua on the field algebra.Dedicated to Huzihiro ArakiResearch supported by MURST and CNR, GNAFA 相似文献
170.
Natalini B Marinozzi M Sardella R Macchiarulo A Pellicciari R 《Journal of chromatography. A》2004,1033(2):363-367
The chromatographic resolution of enantiomeric amino acids is accomplished on a reversed phase column using aqueous mobile phase containing the chiral reagent N,N-dimethyl-S-phenylalanine-Cu(II). The separation is a result of the whole interaction between the diastereomeric complex surface and the mixed stationary phase realized by the dynamic coating of the RP-18 carbon chains layer. The elution order seems to be related to the different water coordination capability on copper ion in the formation of the mixed ternary complexes. 相似文献