全文获取类型
收费全文 | 11628篇 |
免费 | 554篇 |
国内免费 | 937篇 |
专业分类
化学 | 6356篇 |
晶体学 | 126篇 |
力学 | 200篇 |
综合类 | 22篇 |
数学 | 4213篇 |
物理学 | 2202篇 |
出版年
2024年 | 8篇 |
2023年 | 62篇 |
2022年 | 208篇 |
2021年 | 166篇 |
2020年 | 177篇 |
2019年 | 263篇 |
2018年 | 231篇 |
2017年 | 221篇 |
2016年 | 201篇 |
2015年 | 205篇 |
2014年 | 297篇 |
2013年 | 993篇 |
2012年 | 429篇 |
2011年 | 686篇 |
2010年 | 609篇 |
2009年 | 873篇 |
2008年 | 906篇 |
2007年 | 828篇 |
2006年 | 746篇 |
2005年 | 563篇 |
2004年 | 568篇 |
2003年 | 520篇 |
2002年 | 457篇 |
2001年 | 282篇 |
2000年 | 281篇 |
1999年 | 250篇 |
1998年 | 224篇 |
1997年 | 211篇 |
1996年 | 194篇 |
1995年 | 228篇 |
1994年 | 184篇 |
1993年 | 155篇 |
1992年 | 167篇 |
1991年 | 111篇 |
1990年 | 93篇 |
1989年 | 97篇 |
1988年 | 68篇 |
1987年 | 60篇 |
1986年 | 42篇 |
1985年 | 44篇 |
1984年 | 38篇 |
1983年 | 20篇 |
1982年 | 28篇 |
1981年 | 26篇 |
1980年 | 23篇 |
1979年 | 22篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1976年 | 16篇 |
1975年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Motivated by the work of Crapo and Rota [6] on the lifting of a projective complex, we introduce a class of invariant operations associated to integral-weighted graphs, which we call graphical operations. Such operations generalize the sixth harmonic of a quadranguler set on a projective line. We determine the expansion of the graphical operations in terms of multi-linear bracket polynomials in a Grassmann-Cayley algebra. Reducibility and compositions of such invariant operations are also investigated with a number of examples.Supported by Courant Instructorship, New York University. 相似文献
82.
83.
We consider the Abelian gauge theory related to the interaction between the solitary waves of the nonlinear Klein-Gordon equation
and the electromagnetic field. We analyze the existence of electromagnetostatic solutions and, in particular, of vortices.
Dedicated to the memory of Professor Aldo Cossu 相似文献
84.
S. Sarkar A. D. Thakur C. V. Tomy G. Balakrishnan D. McK Paul S. Ramakrishnan A. K. Grover 《Pramana》2006,66(1):193-207
New experimental data are presented on the scan rate dependence of the magnetization hysteresis width ΔM(H) (∞ critical current densityJ
c(H)) in isothermalMH scans in a weakly pinned single crystal of Ca3Rh4Sn13, which displays second magnetization peak (SMP) anomaly as distinct from the peak effect (PE). We observe an interesting
modulation in the field dependence of a parameter which purports to measure the dynamical annealing of the disordered bundles
of vortices injected through the sample edges towards the destined equilibrium vortex state at a givenH. These data, in conjunction with the earlier observations made while studying the thermomagnetic history dependence inJ
c(H) in the tracing of the minor hysteresis loops, imply that the partially disordered state heals towards the more ordered state
between the peak field of the SMP anomaly and the onset field of the PE. The vortex phase diagram in the given crystal of
Ca3Rh4Sn13 has been updated in the context of the notion of the phase coexistence of the ordered and disordered regions between the
onset field of the SMP anomaly and the spinodal line located just prior to the irreversibility line. A multi-critical point
and a critical point in the (H,T) region of the Bragg glass phase have been marked in this phase diagram and the observed behavior is discussed in the light
of recent data on multi-critical point in the vortex phase diagram in a single crystal of Nb. 相似文献
85.
86.
87.
88.
原伊鲁烷型倍半萜醇芳香酸酯的碳谱研究 总被引:4,自引:0,他引:4
作者自人工发酵得到的蜜环菌Armillaria mellea (Vahl.ex Fr.) Quel.菌丝体中分离出十七个原伊鲁烷型倍半萜醇芳香酸翻,在研究这些化合物的化学结构中,对其全去偶碳谱,偏共振谱或INEPT谱,C-H COSY谱和远程C-H COSY谱进行比较仔细地分析,指定了每个化合物各碳的归属,讨论了其碳谱的特征,并指出13C NMR谱是对新的该类型化合物结构测定的有效方法. 相似文献
89.
13
C NMR spectra of some azole series have been investigated: 2-pyridylbenzimidazoles, 2-pyridylimidazo [4,5-b]-pyridines, 2-pyridylimidazo[4,5-c]-pyridines, analogous oxazole compounds, as well as their mono- and bisquaternary salts. Some problems, related to the structure of these compounds in solution, have been discussed.V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow 117975. Torino University, Italy. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 866–872, April, 1992. 相似文献
90.
H. Zöschinger 《Periodica Mathematica Hungarica》1992,25(1):1-11