全文获取类型
收费全文 | 2632篇 |
免费 | 61篇 |
国内免费 | 25篇 |
专业分类
化学 | 1625篇 |
晶体学 | 15篇 |
力学 | 82篇 |
数学 | 443篇 |
物理学 | 553篇 |
出版年
2020年 | 30篇 |
2019年 | 31篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 46篇 |
2015年 | 33篇 |
2014年 | 41篇 |
2013年 | 123篇 |
2012年 | 119篇 |
2011年 | 102篇 |
2010年 | 52篇 |
2009年 | 67篇 |
2008年 | 127篇 |
2007年 | 138篇 |
2006年 | 123篇 |
2005年 | 99篇 |
2004年 | 81篇 |
2003年 | 77篇 |
2002年 | 93篇 |
2001年 | 63篇 |
2000年 | 45篇 |
1999年 | 33篇 |
1998年 | 29篇 |
1997年 | 39篇 |
1996年 | 50篇 |
1995年 | 33篇 |
1994年 | 36篇 |
1993年 | 43篇 |
1992年 | 33篇 |
1991年 | 22篇 |
1990年 | 24篇 |
1989年 | 31篇 |
1988年 | 34篇 |
1987年 | 35篇 |
1986年 | 34篇 |
1985年 | 55篇 |
1984年 | 50篇 |
1983年 | 30篇 |
1982年 | 47篇 |
1981年 | 27篇 |
1980年 | 31篇 |
1979年 | 32篇 |
1978年 | 41篇 |
1977年 | 28篇 |
1976年 | 34篇 |
1975年 | 33篇 |
1974年 | 42篇 |
1973年 | 35篇 |
1969年 | 16篇 |
1968年 | 18篇 |
排序方式: 共有2718条查询结果,搜索用时 15 毫秒
1.
This paper deals mainly with generalizations of results in finitary combinatorics to infinite ordinals. It is well-known that for finite ordinals ∑bT<αβ is the number of 2-element subsets of an α-element set. It is shown here that for any well-ordered set of arbitrary infinite order type α, ∑bT<αβ is the ordinal of the set M of 2-element subsets, where M is ordered in some natural way. The result is then extended to evaluating the ordinal of the set of all n-element subsets for each natural number n ≥ 2. Moreover, series ∑β<αf(β) are investigated and evaluated, where α is a limit ordinal and the function f belongs to a certain class of functions containing polynomials with natural number coefficients. The tools developed for this result can be extended to cover all infinite α, but the case of finite α appears to be quite problematic. 相似文献
2.
3.
Analysis of amlodipine in human plasma by gas chromatography 总被引:3,自引:0,他引:3
4.
5.
Aminonaphthols are easily transformed into a variety of 1- and 2-naphthyl piperazines using a sequence of diazotization, iodide substitution and Pd(0) catalyzed coupling reactions. 相似文献
6.
John L. Wood Johannes Schwarzenberg Edward F. Zganjar Dubravka Rupnik 《Hyperfine Interactions》1992,75(1-4):51-58
State-of-the-art spectroscopy of nuclei far from stability has achieved an extraordinary level of sophistication and detail
in the last ten years. In principle, if a state can be populated, it can be characterized by its energy, spin, parity, and
major decay paths. Sometimes its lifetime can be measured. In practice, one is confronted with enormous complexity. To convert
raw spectroscopic data into nuclear structure data involves a complex process of disentangling gamma rays and conversion electrons
into decay schemes. Specifically, coincidence techniques, especially coincidence intensities, play a crucial role in this
process. Recent examples and methods from work done at UNISOR are presented. 相似文献
7.
We utilize the unifying framework of families of convexity spaces for the treatment of various notions of planar convexity and the associated convex hulls. Our major goal is to prove the refinement and decomposition theorems for families of convexity spaces. These general theorems are then applied to two examples: restricted-oriented convex sets andNESW-convex sets. The applications demonstrate the usefulness of these general theorems, since they give rise to simple algorithms for the computation of the associated convex hulls of polygons. 相似文献
8.
R. Hart P. Hue D. Burton G. F. Robertshaw F. G. H. Tate L. A. Warren und P. Eisenstein 《Fresenius' Journal of Analytical Chemistry》1938,115(7-8):272-274
Ohne Zusammenfassung 相似文献
9.
Joe Warren Scott Schaefer Anil N. Hirani Mathieu Desbrun 《Advances in Computational Mathematics》2007,27(3):319-338
In this paper we provide an extension of barycentric coordinates from simplices to arbitrary convex sets. Barycentric coordinates
over convex 2D polygons have found numerous applications in various fields as they allow smooth interpolation of data located
on vertices. However, no explicit formulation valid for arbitrary convex polytopes has been proposed to extend this interpolation
in higher dimensions. Moreover, there has been no attempt to extend these functions into the continuous domain, where barycentric
coordinates are related to Green’s functions and construct functions that satisfy a boundary value problem. First, we review
the properties and construction of barycentric coordinates in the discrete domain for convex polytopes. Next, we show how
these concepts extend into the continuous domain to yield barycentric coordinates for continuous functions. We then provide
a proof that our functions satisfy all the desirable properties of barycentric coordinates in arbitrary dimensions. Finally,
we provide an example of constructing such barycentric functions over regions bounded by parametric curves and show how they
can be used to perform freeform deformations.
相似文献
10.
Mauel M.E. Warren H.H. Hasegawa A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(6):626-630
A new laboratory terrella has been constructed in order to study collisionless radial diffusion of particles trapped within a dipole magnetic field. Columbia's collisionless terrella experiment (CTX) aims to reproduce the process of wave-induced radial transport and does not try to simulate magnetospheric structure. The first experiment planned for CTX is the direct measurement of stochastic radial diffusion induced from wave-particle drift resonances. The motivation for the CTX experiment is described, and the procedures to be used to measure the intensity and spectrum of fluctuations generating chaos, the rate of radial transport, and the evolution of the density and pressure profiles are illustrated. Because of the success of similar experiments conducted earlier in a long thin magnetic mirror, these dipole experiments can be performed with a high degree of confidence. An example from these earlier experiments is presented 相似文献