全文获取类型
收费全文 | 2946篇 |
免费 | 84篇 |
国内免费 | 22篇 |
专业分类
化学 | 1824篇 |
晶体学 | 25篇 |
力学 | 93篇 |
数学 | 478篇 |
物理学 | 632篇 |
出版年
2022年 | 19篇 |
2021年 | 38篇 |
2020年 | 36篇 |
2019年 | 47篇 |
2018年 | 37篇 |
2017年 | 27篇 |
2016年 | 66篇 |
2015年 | 65篇 |
2014年 | 47篇 |
2013年 | 131篇 |
2012年 | 114篇 |
2011年 | 139篇 |
2010年 | 80篇 |
2009年 | 56篇 |
2008年 | 100篇 |
2007年 | 119篇 |
2006年 | 121篇 |
2005年 | 145篇 |
2004年 | 115篇 |
2003年 | 118篇 |
2002年 | 106篇 |
2001年 | 64篇 |
2000年 | 66篇 |
1999年 | 31篇 |
1998年 | 24篇 |
1997年 | 44篇 |
1996年 | 43篇 |
1995年 | 38篇 |
1994年 | 43篇 |
1993年 | 47篇 |
1992年 | 54篇 |
1991年 | 43篇 |
1990年 | 47篇 |
1989年 | 39篇 |
1988年 | 43篇 |
1987年 | 27篇 |
1986年 | 31篇 |
1985年 | 45篇 |
1984年 | 36篇 |
1983年 | 39篇 |
1982年 | 40篇 |
1981年 | 37篇 |
1980年 | 38篇 |
1979年 | 30篇 |
1978年 | 39篇 |
1977年 | 28篇 |
1976年 | 38篇 |
1975年 | 29篇 |
1974年 | 42篇 |
1973年 | 41篇 |
排序方式: 共有3052条查询结果,搜索用时 15 毫秒
1.
J. B. Lewis E. L. Baldeschwieler L. D. Tabern E. F. Shelberg D. Hillis S. Cromer I. F. Bingham S. Givaudon M. Aubert M. R. Moutte A. Andant P. Lambert J. Lecomte J. Tausz H. Wolf B. Gordon W. Dachnow I. Perrier M. Lobunetz M. O. Chaikin C. Engler D. Holde 《Analytical and bioanalytical chemistry》1940,119(7-8):307-310
2.
The magnetic properties of existing amorphous iron based materials, i.e., Fe--metalloid, Fe--early transition metals and Fe--rare
earth alloys, are briefly discussed for some representative alloys. The spin orientation of amorphous Fe--metalloid alloys
has been determined by the angular dependence of hyperfine interactions. It is shown that in iron--early transition metals
ferromagnetic order is not long-ranged, but determined by magnetic clusters. The magnetic hyperfine field distributions of
Fe-rich iron--early transition metals consist of a high and a low field tail. The magnetic structure has been investigated
for two representative Fe--RE (RE = Er, Ce) amorphous alloys. For the first time, the magnetic coupling phenomenon in amorphous/crystalline
multilayers has been discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
A. Sánchez-Lavega A. Salazar A. Ocariz L. Pottier E. Gomez L.M. Villar E. Macho 《Applied Physics A: Materials Science & Processing》1997,65(1):15-22
Received: 16 September 1996/Accepted: 6 January 1997 相似文献
4.
The N-carboethoxy precursor to (±)-tecomanine has been prepared in 11 steps from 2-methyl-1-buten-3-yne. The key step, Pauson-Khand cyclization of a methylated 5-aza-6-nonen-1-yne succeeds, but only in low yield, a consequence of the dialkyl substitution about the azaenyne framework. Nevertheless, the overall sequence to that point is one of the more efficient to be described. 相似文献
5.
6.
Muscarine, oxazole, thiazole, imidazole and peptide alkaloids and other miscellaneous alkaloids. 总被引:1,自引:0,他引:1
J R Lewis 《Natural product reports》1992,9(1):81-101
7.
P G Stelmachowicz D E Lewis L L Larson W Jesteadt 《The Journal of the Acoustical Society of America》1987,81(6):1881-1887
Growth-of-masking functions were obtained from 19 normal and 5 hearing-impaired listeners using a simultaneous-masking paradigm. When masker and probe frequency are identical, the slope of masking approximates 1.0 for both normal-hearing and impaired listeners. For masker frequencies less than or greater than probe frequency, the slopes for impaired listeners are shallower than those of normals. These findings are consistent with previously reported physiological data (single-fiber rate versus level and AP masking functions) for animals with induced cochlear lesions. Results are discussed in terms of a potential masking technique to estimate the growth of response in normal and impaired ears. 相似文献
8.
Mark L. Lewis 《Algebras and Representation Theory》2002,5(3):277-304
Let G be a solvable group with five character degrees. Suppose that there is some prime p so that G/O
p
(G) is not Abelian. Also, assume that cd(G) contains a degree that is not divisible by p. Under these hypotheses, we show that the derived length of G is at most 4. 相似文献
9.
Scott P. Lewis Cengiz Alacaci George E. O'Brien Zhonghong Jiang 《School science and mathematics》2002,102(4):172-180
The use of a project‐based science (PBS) approach to teaching encourages students to integrate mathematics and science in meaningful ways as they create projects. As a beginning study of how students use mathematics in such an approach, an analysis of 23 projects developed by preservice elementary teachers enrolled in an elementary science course was conducted. Findings showed that students made a number of different types of mathematical errors and underutilized data representation and summary forms. Implications included the importance of developing methods for supporting the use of mathematical tools in utilizing a project‐based approach and considering ways that such tools mediate scientific thinking. 相似文献
10.
Rhyd Lewis 《Journal of Heuristics》2007,13(4):387-401
In this paper we present, to our knowledge, the first application of a metaheuristic technique to the very popular and NP-complete
puzzle known as ‘sudoku’. We see that this stochastic search-based algorithm, which uses simulated annealing, is able to complete
logic-solvable puzzle-instances that feature daily in many of the UK’s national newspapers. We also introduce a new method
for producing sudoku problem instances (that are not necessarily logic-solvable) and use this together with the proposed SA
algorithm to try and discover for what types of instances this algorithm is best suited. Consequently we notice the presence
of an ‘easy-hard-easy’ style phase-transition similar to other problems encountered in operational research. 相似文献