全文获取类型
收费全文 | 4377篇 |
免费 | 164篇 |
国内免费 | 9篇 |
专业分类
化学 | 2895篇 |
晶体学 | 54篇 |
力学 | 99篇 |
数学 | 360篇 |
物理学 | 1142篇 |
出版年
2023年 | 43篇 |
2022年 | 71篇 |
2021年 | 75篇 |
2020年 | 107篇 |
2019年 | 125篇 |
2018年 | 78篇 |
2017年 | 72篇 |
2016年 | 159篇 |
2015年 | 93篇 |
2014年 | 155篇 |
2013年 | 277篇 |
2012年 | 286篇 |
2011年 | 356篇 |
2010年 | 205篇 |
2009年 | 172篇 |
2008年 | 266篇 |
2007年 | 224篇 |
2006年 | 203篇 |
2005年 | 154篇 |
2004年 | 144篇 |
2003年 | 107篇 |
2002年 | 93篇 |
2001年 | 73篇 |
2000年 | 68篇 |
1999年 | 51篇 |
1998年 | 34篇 |
1997年 | 33篇 |
1996年 | 47篇 |
1995年 | 37篇 |
1994年 | 47篇 |
1993年 | 50篇 |
1992年 | 42篇 |
1991年 | 30篇 |
1990年 | 17篇 |
1989年 | 28篇 |
1988年 | 25篇 |
1987年 | 36篇 |
1986年 | 25篇 |
1985年 | 25篇 |
1984年 | 41篇 |
1983年 | 24篇 |
1982年 | 33篇 |
1981年 | 37篇 |
1980年 | 29篇 |
1979年 | 29篇 |
1978年 | 19篇 |
1977年 | 21篇 |
1976年 | 20篇 |
1975年 | 18篇 |
1973年 | 15篇 |
排序方式: 共有4550条查询结果,搜索用时 15 毫秒
1.
Molecular Diversity - The antifungals that are in current clinical practice have a high occurrence of a side effect and multidrug resistance (MDR). Researchers across the globe are trying to... 相似文献
2.
3.
4.
5.
It is explicitly shown that if phase transition occurs at the core of a newborn neutron star with moderately strong magnetic
field strength, which populates only the electron’s Landau levels, then in the β -equilibrium condition, the quark core is
energetically much more unstable than the neutron matter of identical physical condition. 相似文献
6.
An exact formalism for the relativistic version of Landau theory of Fermi liquid in presence of strong quantizing magnetic field is developed. Both direct and exchange type interactions with scalar and vector coupling cases are considered. 相似文献
7.
B. Ghosh 《等离子体物理论文集》1989,29(2):125-134
To describe the long time asymptotic behaviour of weakly nonlinear plasma waves propagating in a strongly magnetized plasmafilled cylindrical waveguide the usual KDV equation which is first order in wave amplitude is extended to second order including the effects of finite temperature, mobile ions and giving a proper treatment to the radial co-ordinate for all possible modes of propagation. The second-order effects on the first-order solitary wave profile, phase speed and first order correction to the wavelength are all determined and discussed. 相似文献
8.
9.
The study of the angular distribution of slow particles during high energy hadron-nucleus interaction indicates that emission of slow particles takes place from a thermally non-equilibrated system. This evidence has come out from the presence of intermittency - a phenomenon that reveals a fractal structure and represents a self-similarity in the particle production process. Hence, this study highlights inadequacy of cascade-evaporation model and advocates the need of its refinement. 相似文献
10.
Govindarajan Sankar A. Sultan Nasar 《Journal of polymer science. Part A, Polymer chemistry》2007,45(8):1557-1570
A series of substituted N‐methylaniline‐blocked polyisocyanates based on 4,4′‐methylenebis(phenyl isocyanate) and poly(tetrahydrofuran) were prepared and characterized thoroughly with FTIR, 1H NMR, and 13C NMR spectroscopy methods. Compared with unsubstituted N‐methylaniline, a blocking agent with an electron‐releasing substituent at the para position took a shorter time, whereas those with an electron‐releasing substituent at the ortho position or an electron‐withdrawing substituent at the ortho and para positions took longer times for the blocking reaction. The thermal dissociation reactions of blocked polyisocyanates were carried out with an FTIR spectrophotometer attached to hot‐stage accessories under dynamic and isothermal conditions. The dynamic method was used to determine the deblocking temperature, and the isothermal method was used to calculate the deblocking kinetics and activation parameters. The cure times of blocked polyisocyanates with hydroxyl‐terminated polybutadiene were also determined. The deblocking temperatures, the results of cure‐time studies, and the kinetic parameters revealed that the thermal dissociation of the N‐methylaniline‐blocked polyisocyanates was retarded by electron‐donating substituents and facilitated by electron‐withdrawing substituents. The action of N‐methylanilines as blocking agents for isocyanate was explained by the formation of a four‐center, intramolecularly hydrogen‐bonded ring structure during the thermal dissociation of the blocked polyisocyanates. The formation of such a hydrogen‐bonded ring structure was confirmed and supported by variable‐temperature 1H NMR studies and entropy parameters, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1557–1570, 2007 相似文献