全文获取类型
收费全文 | 43466篇 |
免费 | 8578篇 |
国内免费 | 9132篇 |
专业分类
化学 | 32838篇 |
晶体学 | 991篇 |
力学 | 2934篇 |
综合类 | 850篇 |
数学 | 5171篇 |
物理学 | 18392篇 |
出版年
2024年 | 95篇 |
2023年 | 695篇 |
2022年 | 1382篇 |
2021年 | 1538篇 |
2020年 | 1682篇 |
2019年 | 1745篇 |
2018年 | 1499篇 |
2017年 | 1686篇 |
2016年 | 1997篇 |
2015年 | 2280篇 |
2014年 | 2818篇 |
2013年 | 3538篇 |
2012年 | 4062篇 |
2011年 | 4276篇 |
2010年 | 3320篇 |
2009年 | 3478篇 |
2008年 | 3801篇 |
2007年 | 3197篇 |
2006年 | 2986篇 |
2005年 | 2458篇 |
2004年 | 1848篇 |
2003年 | 1492篇 |
2002年 | 1548篇 |
2001年 | 1327篇 |
2000年 | 1264篇 |
1999年 | 876篇 |
1998年 | 567篇 |
1997年 | 483篇 |
1996年 | 441篇 |
1995年 | 378篇 |
1994年 | 387篇 |
1993年 | 333篇 |
1992年 | 282篇 |
1991年 | 198篇 |
1990年 | 224篇 |
1989年 | 159篇 |
1988年 | 154篇 |
1987年 | 117篇 |
1986年 | 102篇 |
1985年 | 69篇 |
1984年 | 52篇 |
1983年 | 61篇 |
1982年 | 23篇 |
1981年 | 32篇 |
1980年 | 25篇 |
1979年 | 34篇 |
1978年 | 12篇 |
1977年 | 16篇 |
1974年 | 10篇 |
1925年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
143.
Investigation of remelting and cladding processing with laminar plasma jets on several metals has been conducted looking for possible development of a new surface modification technique. The remelting tests illustrated that the new method could evidently improve the material microstructure and properties of cast iron. The cladding was done with Al2O3 ceramic powder on stainless steel. The energy dispersive spectra (EDS) analysis was used to determine the distribution of the major cladding element in the plasma-processed layers, for which the microstructure observations and hardness measurements were also performed. 相似文献
144.
C.-S. Huang T. Li L. Wei Q.-S. Yan 《The European Physical Journal C - Particles and Fields》2002,23(1):195-199
It is shown that new sources of CP violation can be generated in models with more than one extra dimension. In the supersymmetric models on the space-time , where the radius moduli have auxiliary vacuum expectation values and the supersymmetry breaking is mediated by the Kaluza–Klein
states of the gauge supermultiplets, we analyze the gaugino masses and trilinear couplings for two scenarios and obtain the
result that there exist relative CP violating phases among the gaugino masses and trilinear couplings.
Received: 10 October 2001 / Published online: 20 December 2001 相似文献
145.
ZHANG Lin-bo LIU Xiao-hua JIANG Yuan GUO Ping SHA Li-jin LI Yu 《高等学校化学研究》2006,22(2):139-144
After establishing hemi-Parkinsonian rat models, the relationships between neuron death and the expression of several proteins, such as c-Fos, GFAP, GDNF, NF-κB and some cytokines were determined. Therapeutics experiments with notoginsenoside-Rg1 were carried out. The research results show that the expressions of GFAP, NF-Kκ and c-Fos will obviously increase in the lesion side of the striatum and the expression of GDNF will decrease, which implies that the signal transduction pathway may participate in the apoptosis in neurons. The levels of some cytokines such as TNF-α, IL-1β in the striatum of PD rat models increased compared to those of normal rats. The results of the therapeutics experiments show that notoginsenoside-Rg1 may repress the immune inflammation response and regulate the immune function through the neuro-immune molecular network. Therefore, notoginsenoside-Rg1 can be used as an effective drug for anti-oxidation and anti-inflammation, and can be used in the therapy of Parkinson's disease(PD). 相似文献
146.
147.
148.
X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic recombination, collisional ionization and resonance excitation from the neighbouring ion (Al^9+ and Al^11+ ) charge states of the target ion (Al^10+) are considered in the model. In addition, the contributions of different atomic processes to the x-ray spectrum are analysed. The results show that dielectronic recombination, radiative recombination, collisional ionization and resonance excitation, other than direct collisional excitation, are very important processes. 相似文献
149.
150.
Long JIANG 《数学年刊B辑(英文版)》2006,27(5):553-564
Abstract
Under the Lipschitz assumption and square integrable assumption on g, the author proves that Jensen’s inequality holds for backward stochastic differential equations with generator g if and only if g is independent of y, g(t, 0) ≡ 0 and g is super homogeneous with respect to z. This result generalizes the known results on Jensen’s inequality for g- expectation in [4, 7–9].
*Project supported by the National Natural Science Foundation of China (No.10325101) and the Science Foundation of China University
of Mining and Technology. 相似文献