全文获取类型
收费全文 | 559421篇 |
免费 | 5443篇 |
国内免费 | 2712篇 |
专业分类
化学 | 291468篇 |
晶体学 | 7830篇 |
力学 | 26594篇 |
综合类 | 27篇 |
数学 | 72553篇 |
物理学 | 169104篇 |
出版年
2021年 | 5618篇 |
2020年 | 6000篇 |
2019年 | 6762篇 |
2018年 | 9067篇 |
2017年 | 9165篇 |
2016年 | 12814篇 |
2015年 | 7163篇 |
2014年 | 11461篇 |
2013年 | 25669篇 |
2012年 | 20690篇 |
2011年 | 24317篇 |
2010年 | 17877篇 |
2009年 | 17762篇 |
2008年 | 22547篇 |
2007年 | 22344篇 |
2006年 | 20202篇 |
2005年 | 18137篇 |
2004年 | 17134篇 |
2003年 | 15151篇 |
2002年 | 14936篇 |
2001年 | 15280篇 |
2000年 | 11804篇 |
1999年 | 9140篇 |
1998年 | 7929篇 |
1997年 | 7736篇 |
1996年 | 7256篇 |
1995年 | 6503篇 |
1994年 | 6469篇 |
1993年 | 6276篇 |
1992年 | 6591篇 |
1991年 | 7013篇 |
1990年 | 6708篇 |
1989年 | 6597篇 |
1988年 | 6426篇 |
1987年 | 6243篇 |
1986年 | 5966篇 |
1985年 | 7574篇 |
1984年 | 7906篇 |
1983年 | 6642篇 |
1982年 | 6917篇 |
1981年 | 6433篇 |
1980年 | 6087篇 |
1979年 | 6591篇 |
1978年 | 6818篇 |
1977年 | 6697篇 |
1976年 | 6659篇 |
1975年 | 6369篇 |
1974年 | 6190篇 |
1973年 | 6492篇 |
1972年 | 4743篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
This paper deals with a singular perturbation of the stationary Stokes and Navier-Stokes systems. The term ε2Δp is added to the continuity equation, where ε is a small parameter. For a domain with cylindrical outlets to infinity and exponentially decaying data, existence and uniqueness of solutions under flux conditions at infinity are established for the linear problem and also for the nonlinear problem in the case of small data. Asymptotically exact estimates are proved for ε tending to zero. For sufficiently regular data, these estimates imply the convergence in H
loc
5/2−δ
for the velocity parts and in H
loc
3/2−δ
for the pressure parts, respectively. Bibliography: 17 titles.Dedicated to V. A. Solonnikov on the occasion of his 70th birthday__________Published in Zapiski Nauchnykh Seminarov POMI, Vol. 306, 2003, pp. 107–133. 相似文献
232.
233.
Studies of thickness and temperature dependencies of the dielectric susceptibility of nitrobenzene interlayers formed on conductive substrates were carried out. The obtained data were processed under the assumption of the existence of dimers (with opposite directions of molecular dipole moments) in orientationally ordered wall-adjacent layers. The results were treated on the basis of Lifshits theory. 相似文献
234.
A. Peláiz-Barranco O. García-Zaldívar F. Calderón-Piñar 《Solid State Communications》2005,133(8):515-519
The Ac behaviour of PLZT 6/80/20 ferroelectric ceramics was analyzed around and above the phase transition. Two relaxation processes are identified, showing that the so-called ‘universal relaxation law’ holds for the ceramics. A critical point in the values of the Ac conductivity, around the temperature corresponding to the maximum of the dielectric losses, is observed below the transition temperature due to the relaxor behaviour. The frequency dependence of the Ac conductivity at various temperatures and the hysteresis loops show classical relaxor behaviour with a diffuse phase transition. 相似文献
235.
236.
Morey Timothy E. Varshney Manoj Flint Jason A. Seubert Christoph N. Smith W. Brit Bjoraker David G. Shah Dinesh O. Dennis Donn M. 《Journal of nanoparticle research》2004,6(2):159-170
Background: Although microemulsion-based nanoparticles (MEs) may be useful for drug delivery or scavenging, these benefits must be balanced against potential nanotoxicological effects in biological tissue (bio-nano interface). We investigated the actions of assembled MEs and their individual components at the bio-nano interface of thrombosis and hemolysis in human blood.
Methods: Oil-in-water MEs were synthesized using ethylbutyrate, sodium caprylate, and pluronic F-68 (ME4) or F-127 (ME6) in 0.9% NaClw/v. The effects of MEs or components on thrombosis were determined using thrombo-elastography, platelet contractile force, clot elastic modulus, and platelet counting. For hemolysis, ME or components were incubated with erythrocytes, centrifuged, and washed for measurement of free hemoglobin by spectroscopy.
Results and conclusions: The mean particle diameters (polydispersity index) for ME6 and ME4 were 23.6 ± 2.5 nm (0.362) and 14.0 ± 1.0 nm (0.008), respectively. MEs (0, 0.03, 0.3, 3 mM) markedly reduced the thromboelastograph maximal amplitude in a concentration-dependent manner (49.0 ± 4.2, 39.0 ± 5.6, 15.0 ± 8.7, 3.8 ± 1.3 mm, respectively), an effect highly correlated (r2 = 0.94) with similar changes caused by pluronic surfactants (48.7 ± 10.9, 30.7 ± 15.8, 20.0 ± 11.3, 2.0 ± 0.5) alone. Neither oil nor sodium caprylate alone affected the thromboelastograph. The clot contractile force was reduced by ME (27.3 ± 11.1–6.7 ± 3.4 kdynes/cm2, P = 0.02, n = 5) whereas the platelet population not affected (175 ± 28–182 ± 23 106/ml, P = 0.12, n = 6). This data suggests that MEs reduced platelet activity due to associated pluronic surfactants, but caused minimal changes in protein function necessary for coagulation. Although pharmacological concentrations of sodium caprylate caused hemolysis (EC50 = 213 mM), MEs and pluronic surfactants did not disrupt erythrocytes. Knowledge of nanoparticle activity and potential associated nanotoxicity at this bio-nano interface enables rational ME design for in vivo applications. 相似文献
237.
238.
239.
240.
Mathematical Notes - 相似文献