全文获取类型
收费全文 | 667253篇 |
免费 | 5040篇 |
国内免费 | 1516篇 |
专业分类
化学 | 327977篇 |
晶体学 | 9596篇 |
力学 | 35629篇 |
综合类 | 19篇 |
数学 | 95688篇 |
物理学 | 204900篇 |
出版年
2021年 | 6212篇 |
2020年 | 6719篇 |
2019年 | 7688篇 |
2018年 | 10509篇 |
2017年 | 10737篇 |
2016年 | 14665篇 |
2015年 | 7725篇 |
2014年 | 13312篇 |
2013年 | 29117篇 |
2012年 | 22866篇 |
2011年 | 27062篇 |
2010年 | 20719篇 |
2009年 | 20635篇 |
2008年 | 25725篇 |
2007年 | 25542篇 |
2006年 | 23317篇 |
2005年 | 20745篇 |
2004年 | 19379篇 |
2003年 | 17583篇 |
2002年 | 17540篇 |
2001年 | 18236篇 |
2000年 | 14209篇 |
1999年 | 10994篇 |
1998年 | 9759篇 |
1997年 | 9532篇 |
1996年 | 8895篇 |
1995年 | 7933篇 |
1994年 | 8018篇 |
1993年 | 7805篇 |
1992年 | 8107篇 |
1991年 | 8658篇 |
1990年 | 8371篇 |
1989年 | 8268篇 |
1988年 | 7974篇 |
1987年 | 7821篇 |
1986年 | 7403篇 |
1985年 | 9309篇 |
1984年 | 9833篇 |
1983年 | 8293篇 |
1982年 | 8645篇 |
1981年 | 8087篇 |
1980年 | 7624篇 |
1979年 | 8382篇 |
1978年 | 8586篇 |
1977年 | 8628篇 |
1976年 | 8626篇 |
1975年 | 8231篇 |
1974年 | 8045篇 |
1973年 | 8272篇 |
1972年 | 6348篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
212.
213.
D. N. Karimov E. A. Krivandina Z. I. Zhmurova B. P. Sobolev V. A. Bezhanov S. P. Chernov G. M. Shapochkin 《Crystallography Reports》2006,51(6):1009-1015
Crystalline materials that are transparent in the vacuum UV spectral region and currently used have been reviewed. Transmission of crystals of solid solutions with the fluorite structure Ca1?x R xF2+x (R = Sc, Y, La, Yb, Lu) in the UV and vacuum UV spectral regions has been investigated. It is shown that application of different methods of purification of fluorides from some impurities can significantly improve the optical quality of fluoride multicomponent crystals in the short-wavelength spectral region. 相似文献
214.
215.
Basic principles of the generalized lattice model of multicomponent condensed systems are formulated. Short-range parts of interatomic interactions are taken into account by means of the geometric constraints method. Long-range parts of the interactions are taken into account in mean field approximation. The expression for Helmholtz free energy is obtained. A system of integral equations for the equilibrium distributions of components is derived. The asymptotic properties of its solutions are investigated. Moment expansion of interatomic interactions and localization of integral terms in free energy is obtained. A Ginzburg–Landau-like functional of free energy is derived. 相似文献
216.
217.
218.
In this paper the performances of inhomogeneous dielectric slabs as solar light collectors for both illumination and solar energy applications are analysed. 相似文献
219.
H E Cline W E Lorensen R J Herfkens G A Johnson G H Glover 《Magnetic resonance imaging》1989,7(1):45-54
A three-dimensional examination of blood vessels is provided using MR data from seven cases. The vascular surfaces are constructed with an algorithm that automatically follows the selected artery or vein and generates a projected three-dimensional gradient shaded image. Fast 3DFT pulse sequences were optimized to enhance the time-of-flight contrast of the intravascular region. By increasing the surface threshold value in a three-dimensional head study, the flesh of a patient's face was peeled away to demonstrate the superfacial temporal artery. Gated cardiac images show the great vessels and cardiac chambers. A three-dimensional view of the aorta shows an irregular surface in the vicinity of an adrenal tumor. 3D MR exams provide a non-invasive technique for assessing vascular morphology in a clinical setting. 相似文献
220.
Calculations are performed, using a basis of two-center functions described previously, for excited states of the following three-and four-electron compounds: H2
–, He2
+, He2, Li2
+2. High efficiency is demonstrated for the frozen ionic core approximation and the nonorthogonal orbital method in such calculations. For four-electron systems the practical feasibility of the frozen hybrid core approximation is demonstrated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 53–56, August, 1987. 相似文献