全文获取类型
收费全文 | 237篇 |
免费 | 37篇 |
国内免费 | 42篇 |
专业分类
化学 | 173篇 |
晶体学 | 2篇 |
力学 | 16篇 |
综合类 | 3篇 |
数学 | 44篇 |
物理学 | 78篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 14篇 |
2019年 | 19篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 16篇 |
2014年 | 18篇 |
2013年 | 14篇 |
2012年 | 27篇 |
2011年 | 20篇 |
2010年 | 10篇 |
2009年 | 7篇 |
2008年 | 16篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 15篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1989年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有316条查询结果,搜索用时 31 毫秒
91.
92.
Jie Liu Hui Tang Bo Zhang Xiling Deng Feilang Zhao Peng Zuo Bang-Ce Ye Yingchun Li 《Analytical and bioanalytical chemistry》2016,408(16):4287-4295
93.
This article studies the optimal proportional reinsurance and investment problem under a constant elasticity of variance(CEV) model.Assume that the insurer’s surplus process follows a jump-diffusion process,the insurer can purchase proportional reinsurance from the reinsurer via the variance principle and invest in a risk-free asset and a risky asset whose price is modeled by a CEV model.The diffusion term can explain the uncertainty associated with the surplus of the insurer or the additional small claims.The objective of the insurer is to maximize the expected exponential utility of terminal wealth.This optimization problem is studied in two cases depending on the diffusion term’s explanation.In all cases,by using techniques of stochastic control theory,closed-form expressions for the value functions and optimal strategies are obtained. 相似文献
94.
95.
Ferromagnetic half metallicity with a high spin polarization of 100% was predicted in the bulk Ni0.5Cu0.5O using density-functional theory method. The band gap of majority spin is 3.45 eV for Ni0.5Cu0.5O. The density of states of minority spin at the Fermi level are mainly from Cu 3d and O 2p in the Ni0.5Cu0.5O. The magnetic moments are from Ni 3d states. Ni0.5Zn0.5O and Ni0.5Cd0.5O systems are ferromagnetic insulators, but the magnetic moment of Ni2+ ions is enhanced by the Zn and Cd incorporation. Therefore, Ni0.5Cu0.5O is the potential candidate for spintronics devices because of the predicted high spin polarization. 相似文献
96.
本文建立了惯性系统三轴综合测试台的结构分析模型,用有限元法对其进行了结构静动态特性计算。给出了外框架在实际载荷作用下的静动态特性和整机的动态特性,并在此基础上,对该三轴台外框架进行了静态变形的实际测量。实测表明,理论分析和实测结果相吻合。 相似文献
97.
Based on the frequently-used cyanine dye probe thiazole orange (TO) and Cy3, a novel kind of styryl cyanine dye was designed and synthesized. Carbazole was inserted into the structures of two cyanine dyes, TO and Cy3, to act as a bridge to link the benzothiazole and indole. This modification resulted in a novel kind of carbozole benzothiazole indole cyanine dye with a carbazole-bridged chain. The dyes were characterized by HNMR and MS. The spectra of the novel dyes were also studied and the results showed that the fluorescence wavelength of novel carbazole benzothiazole indole cyanine dye shifted red, the Stokes shift and Fluorescence quantum yields increased and the fluorescence intensity was enhanced compared to that of TO. These results indicated that the novel dye could be used as an excellent fluorescent probe in biological labeling. 相似文献
98.
Zhiyuan Tang Mengqiu Wu Yingchun Li Xiao Zheng Huiying Liu Xuefang Cheng Lin Xu Guangji Wang Haiping Hao 《Analytica chimica acta》2013
NAD(P)H:quinone oxidoreductase 1 (NQO1, DT-diaphorase) is a prognostic biomarker and a potential therapeutic target for various tumors. Therefore, it is of significance to develop a robust method for the absolute quantification of NQO1. This study aimed to develop and validate a LC–MS/MS based method and to test the appropriateness of using non-isotopic analog peptide as the internal standard (IS) by comparing with a stable isotope labeled (SIL) peptide. The chromatographic performance and mass spectra between the selected signature peptide of NQO1 and the non-isotopic peptide were observed to be very similar. The use of the two internal standards was validated appropriate for the absolute quantification of NQO1, as evidenced by satisfactory validation results over a concentration range of 1.62–162 fmol μL−1. This method has been successfully applied to the absolute quantification of NQO1 expression in various tumor cell lines and tissues. NQO1 expression in human tumor tissues is much higher than that in the neighboring normal tissues in both the cases of lung and colon cancer. The quantitative results obtained from the isotopic and non-isotopic methods are quite similar, further supporting that the use of non-isotopic analog peptide as internal standard is appropriate and feasible for the quantification of NQO1. By comparing with a classical isotopic IS, the present study indicates that the use of a non-isotopic peptide analog to the proteotypic peptide as the internal standard can get equal accuracy and preciseness in measuring NQO1. The universal applicability of the non-isotopic IS approach for the quantification of proteins warrants further research. 相似文献
99.
本文证明了不等式‖αp3-β‖<p-1/11有无穷多素数解,其中α为任意无理数,β为任意实数,‖γ‖表示γ距其最近的整数的距离.这一结果改进了Baker和Harman的. 相似文献
100.
本以含高阶项的试函数,用Galerkin法求得了周边固支的钢筋混凝土板在均布荷载作用下的挠度表达式,所得结果在特殊情况下与[1]的各向同性均质板在均布荷载下的结果相符合. 相似文献