全文获取类型
收费全文 | 1254篇 |
免费 | 39篇 |
国内免费 | 4篇 |
专业分类
化学 | 793篇 |
晶体学 | 8篇 |
力学 | 39篇 |
数学 | 244篇 |
物理学 | 213篇 |
出版年
2023年 | 9篇 |
2021年 | 13篇 |
2020年 | 17篇 |
2019年 | 20篇 |
2018年 | 16篇 |
2017年 | 26篇 |
2016年 | 31篇 |
2015年 | 28篇 |
2014年 | 42篇 |
2013年 | 49篇 |
2012年 | 66篇 |
2011年 | 76篇 |
2010年 | 36篇 |
2009年 | 39篇 |
2008年 | 69篇 |
2007年 | 70篇 |
2006年 | 71篇 |
2005年 | 51篇 |
2004年 | 55篇 |
2003年 | 53篇 |
2002年 | 41篇 |
2001年 | 30篇 |
2000年 | 24篇 |
1999年 | 14篇 |
1998年 | 15篇 |
1997年 | 8篇 |
1996年 | 16篇 |
1995年 | 8篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 15篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 15篇 |
1977年 | 10篇 |
1976年 | 16篇 |
1975年 | 15篇 |
1973年 | 11篇 |
1938年 | 7篇 |
排序方式: 共有1297条查询结果,搜索用时 15 毫秒
1.
Jalal M. Nawash Brendan Twamley Kelvin G. Lynn 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(8):i66-i68
Our investigations into the ZnO–TeO2 system have produced a new phase, zinc(II) hexatellurium(IV) tridecaoxide, ZnTe6O13, with trigonal (R) symmetry, synthesized by repeated heating and cooling to a maximum temperature of 1053 K. The asymmetric unit consists of a Zn atom coordinated in a distorted octahedral fashion by two unique tellurium(IV) oxide units that form trigonal–bipyramidal TeO4 and TeO3+1 corner‐ and edge‐shared polyhedra. Except for the Zn and an O atom, which occupy 6c positions, all atoms occupy 18f general positions. 相似文献
2.
3.
4.
5.
Symmetry is one of the most important aesthetic criteria in graph drawing because it reveals structure in the graph. To draw
graphs symmetrically, we employ two steps. The first step is to find appropriate automorphisms. The second step is to draw
the graph to display the automorphisms. Our aim in this paper is to construct maximally symmetric straight line drawings of
triconnected planar graphs in linear time. Previously known algorithms run in quadratic time. We show that an algorithm of
Fontet can be used to find an embedding in the plane with the maximum number of symmetries, and present a new algorithm for
finding a straight line drawing that achieves that maximum. Both algorithms run in linear time. 相似文献
6.
This paper reports a direct jet-based polymerisation by polycondensation approach to forming a self-supporting scaffold structure.
The processing technique is electrospraying, which is also known as electrohydrodynamic atomization. A specially formulated
ethanolic siloxane sol derived from alkoxysilanes was synthesised and electrosprayed using a ring-shaped ground electrode
configuration. The medium was seen to electrospray in the stable cone-jet mode, which later gave rise to the growing or forming
of “fir-tree” like structures. The materials were characterised using microscopy, solid state NMR, FTIR, XRD and DSC. Hence
this paper explains the direct controlled polycondensation from the siloxane sol and further presents the basis by which these
scaffolds take shape. 相似文献
7.
We discuss equivalent definitions of holomorphic second-order cusp forms and prove bounds on their Fourier coefficients. We
also introduce their associated L-functions, prove functional equations for twisted versions of these L-functions and establish a criterion for a Dirichlet series to originate from a second order form. In the last section we
investigate the effect of adding an assumption of periodicity to this criterion.
2000 Mathematics Subject Classification Primary—11F12, 11F66
G. Mason: Research supported in part by NSF Grant DMS 0245225.
C. O’Sullivan: Research supported in part by PSC CUNY Research Award No. 65453-00 34. 相似文献
8.
Brendan D. McKay 《Combinatorica》1990,10(4):367-377
LetRT(n), ED(n) andEOG(n) be the number of labelled regular tournaments, labelled loop-free simple Eulerian digraphs, and labelled Eulerian oriented simple graphs, respectively, onn vertices. Then, asn,, for any>0. The last two families of graphs are also enumerated by their numbers of edges. The proofs use the saddle point method applied to appropriaten-dimensional integrals. 相似文献
9.
10.