全文获取类型
收费全文 | 82932篇 |
免费 | 1330篇 |
国内免费 | 930篇 |
专业分类
化学 | 27416篇 |
晶体学 | 832篇 |
力学 | 6940篇 |
综合类 | 30篇 |
数学 | 32594篇 |
物理学 | 17380篇 |
出版年
2023年 | 127篇 |
2022年 | 159篇 |
2021年 | 194篇 |
2020年 | 223篇 |
2019年 | 191篇 |
2018年 | 10564篇 |
2017年 | 10380篇 |
2016年 | 6301篇 |
2015年 | 1066篇 |
2014年 | 584篇 |
2013年 | 665篇 |
2012年 | 4213篇 |
2011年 | 10975篇 |
2010年 | 5927篇 |
2009年 | 6335篇 |
2008年 | 6900篇 |
2007年 | 9031篇 |
2006年 | 509篇 |
2005年 | 1536篇 |
2004年 | 1700篇 |
2003年 | 2118篇 |
2002年 | 1189篇 |
2001年 | 389篇 |
2000年 | 408篇 |
1999年 | 304篇 |
1998年 | 314篇 |
1997年 | 250篇 |
1996年 | 299篇 |
1995年 | 185篇 |
1994年 | 127篇 |
1993年 | 144篇 |
1992年 | 99篇 |
1991年 | 121篇 |
1990年 | 80篇 |
1989年 | 85篇 |
1988年 | 80篇 |
1987年 | 74篇 |
1986年 | 79篇 |
1985年 | 63篇 |
1984年 | 47篇 |
1983年 | 41篇 |
1982年 | 46篇 |
1981年 | 44篇 |
1980年 | 47篇 |
1979年 | 46篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
181.
Maxim V. Pavlov 《Communications in Mathematical Physics》2007,272(2):469-505
The algebro-geometric approach for integrability of semi-Hamiltonian hydrodynamic type systems is presented. The class of
symmetric hydrodynamic type systems is defined and the calculation of the associated Riemann surfaces is greatly simplified for this
class. Many interesting and physically motivated examples are investigated. 相似文献
182.
通过光谱响应特性实验和记录/读出图像实验,研究了基因变异型细菌视紫红质(BRD96N)分子膜对单色光的光调制特性.发现BRD96N分子膜在550nm—600nm范围内对调制光有吸收增强的现象,且对此范围内不同波长的单色光其调制程度有差异.利用曲线拟和方法发现550nm—600nm吸收增强的变化过程分为快过程和慢过程,其对应的时间常数分别为30s和5min.利用强度调制器的吸收强度与图像灰度之间的关系,分析了560nm—600nm范围内出现图像反转的实验现象.
关键词:
细菌视紫红质D96N分子膜
光谱响应
吸收增强现象
图像反转现象 相似文献
183.
184.
Kwang-Hua W. Chu 《International Journal of Theoretical Physics》2007,46(12):3230-3233
The modified Gross–Pitaevskii equation was derived and solved to obtain the 1D solution in the zero-energy limit. This stationary
solution could account for the dominated contributions due to the kinetic effect as well as the chemical potential in inhomogeneous
Bose gases. 相似文献
185.
Djamel Meraghni Abdelhakim Necir 《Methodology and Computing in Applied Probability》2007,9(4):557-572
The characteristic exponent α of a Lévy-stable law S
α
(σ, β, μ) was thoroughly studied as the extreme value index of a heavy tailed distribution. For 1 < α < 2, Peng (Statist. Probab. Lett. 52: 255–264, 2001) has proposed, via the extreme value approach, an asymptotically normal estimator for the location parameter μ. In this paper, we derive by the same approach, an estimator for the scale parameter σ and we discuss its limiting behavior.
相似文献
186.
187.
188.
189.
ZrO2 nanoparticles was uniformly co-deposited into a nickel matrix by electroplating of nickel from a Watts bath containing particles in suspension which were monodispersed with dispersant under DC electrodeposition condition. It was found that morphology, orientation and hardness of the nanocomposite coatings with monodispersed ZrO2 nanoparticles had lots of difference from the nanocomposite coatings with agglomerated ZrO2 nanoparticles and pure nickel coatings. Especially, the result of hardness showed that only a very low volume percent (less than 1 wt.%) of monodispered ZrO2 nanoparticles in Ni-ZrO2 nanocomposite coatings would result in higher hardness of the coatings. The hardness of Ni-ZrO2 nanocomposite coatings with monodispersed and agglomerated ZrO2 nanoparticles were 529 and 393 HV, respectively. The hardness value of the former composite coatings was over 1.3 times higher than that of the later. All these composite coatings were two-three times higher than that of pure nickel plating (207 HV) prepared under the same condition. The strengthening mechanisms of the Ni-ZrO2 nanocomposite coatings based on a combination of grain refinement strengthening from nickel matrix grain refining and dispersion strengthening from dispersion state of ZrO2 nanoparticles in the coatings. 相似文献
190.
Elizabeth Wulcan 《Arkiv f?r Matematik》2007,45(1):157-178
With a given holomorphic section of a Hermitian vector bundle, one can associate a residue current by means of Cauchy–Fantappiè–Leray
type formulas. In this paper we define products of such residue currents. We prove that, in the case of a complete intersection,
the product of the residue currents of a tuple of sections coincides with the residue current of the direct sum of the sections. 相似文献