全文获取类型
收费全文 | 587篇 |
免费 | 69篇 |
国内免费 | 52篇 |
专业分类
化学 | 235篇 |
晶体学 | 4篇 |
力学 | 109篇 |
综合类 | 14篇 |
数学 | 185篇 |
物理学 | 161篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 21篇 |
2021年 | 14篇 |
2020年 | 17篇 |
2019年 | 15篇 |
2018年 | 18篇 |
2017年 | 20篇 |
2016年 | 29篇 |
2015年 | 31篇 |
2014年 | 24篇 |
2013年 | 32篇 |
2012年 | 34篇 |
2011年 | 36篇 |
2010年 | 30篇 |
2009年 | 43篇 |
2008年 | 30篇 |
2007年 | 20篇 |
2006年 | 20篇 |
2005年 | 16篇 |
2004年 | 18篇 |
2003年 | 38篇 |
2002年 | 30篇 |
2001年 | 19篇 |
2000年 | 25篇 |
1999年 | 29篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有708条查询结果,搜索用时 15 毫秒
661.
662.
Bo Feng Yueping Luo Fei Ge Lu Wang Liqun Huang Youzhi Dai 《Surface and interface analysis : SIA》2011,43(10):1304-1310
Immobilizing proteins on a solid surface in a site‐specific orientation and maintaining their bioactivity are crucial to the construction of high‐performance immunoassays. In this study, an affinity ligand for polystyrene (PS) surface screened from a phage display peptide library, named Lig1, was genetically fused to the N/C‐terminus of chimeric antigen HCV that could be recognized by specific antibodies against hepatitis C virus (HCV). Immunoassay characteristics of lig1‐fused HCVs immobilized on PS surface were compared to that of original HCV in both direct and indirect enzyme‐linked immunosorbent assay (ELISA). The results indicated that HCV‐Lig1 (Lig1 fused to HCV C‐terminus) was preferentially adsorbed on PS surface in a site‐oriented manner and would expose specific antibody‐binding sites well, which resulted in a substantial enhancement of detection sensitivity. AFM images showed that, compared to the original one, HCV‐Lig1 was arranged on PS surface in an ordered state and its conformational and steric distortions induced during the interfacial binding process were much slighter. As long as the specific epitope of a coating antigen is not located on both its N and C‐terminus, the ligand fusion approach could be an ideal strategy for site‐oriented protein immobilization. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
663.
664.
665.
Liqun Ban Boris S. Mordukhovich 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(2):441-461
This paper concerns the study of solution maps to parameterized variational inequalities over generalized polyhedra in reflexive Banach spaces. It has been recognized that generalized polyhedral sets are significantly different from the usual convex polyhedra in infinite dimensions and play an important role in various applications to optimization, particularly to generalized linear programming. Our main goal is to fully characterize robust Lipschitzian stability of the aforementioned solution maps entirely via their initial data. This is done on the basis of the coderivative criterion in variational analysis via efficient calculations of the coderivative and related objects for the systems under consideration. The case of generalized polyhedra is essentially more involved in comparison with usual convex polyhedral sets and requires developing elaborated techniques and new proofs of variational analysis. 相似文献
666.
667.
Hua Zou Shuhuan Li Liqun Zhang Shani Yan Hanguang Wu Shuai Zhang Ming Tian 《Journal of magnetism and magnetic materials》2011,323(12):1643-1651
Silicone rubber microwave absorbing materials (RMAMs) based on ferrite as the major absorbent were prepared by the mechanical blending method. The determining factors for the complex permittivity, complex permeability, and reflectivity of RMAM were thoroughly investigated with various samples including different crystal structures of Ba-ferrite (M-type, W-type, and Y-type), the ferrite with doped elements (Ba, Sr), the materials' thickness, the combination ratio of ferrite and carbonyl iron. The effects of surface modification and loading amount of ferrite on the mechanical properties, processing performance, and absorbing property of RMAM were also assessed. The results show that W-type Ba-ferrite based RMAM exhibits better absorbing property at high frequencies (8-18 GHz) than the other two barium ferrites (M-type and Y-type) based ones, and the absorbing property of RMAM based on Sr-ferrite is best. As the thickness of RMAM and the amount of absorbents increase, the absorption peak moves toward low frequency, the absorption frequency bandwidth is narrowed, and the reflectivity first decreases and later increases. The optimum thickness is 1.5-1.7 mm, and the amount of ferrite is 450 parts per hundreds of rubber (phr). Surface modification of the absorbent with silane coupling agent could improve the mechanical properties and processing performance of RMAM. It is concluded that there will be a synergistic effect when carbonyl iron (CI) is used in combination with Sr-ferrite (Sr-W) in an appropriate proportion. When the total volume fraction of absorbents is 51%, the optimum ratio of Cl to Sr-W is 17:34, the absorption frequency bandwidth (<−10 dB) is about 8 GHz, and the absorption area is −99 dB. 相似文献
668.
中国经济正处于由高速增长转向高质量发展的关键阶段。本文以高效推进经济高质量发展为目标,首先基于对高质量发展内涵的理解,构建一个涵盖宏观、中观以及微观层面的高质量评价指标体系,并从宏中微观三个层面探究了居民消费结构升级对高质量发展的影响机理;同时在把握新时代企业家创新精神和企业家社会责任的内涵基础上,检验了二者在消费结构升级与高质量发展中的调节作用。主要结论如下:第一,消费结构升级从宏、中、微观层面对经济高质量发展起到正向的促进作用;第二,企业家创新精神和企业家社会责任均正向调节了消费结构升级对高质量发展的影响作用。其中,企业家创新精神是通过及时识别市场需求变化并做出理性创新行为,来与消费结构升级这一市场环境变化达到适配效果,从而起到正向的调节效应;此外,企业家社会责任是通过与社会建立合理契约,促进消费者与企业之间的信任等,从而从宏中微观达到对消费结构升级与综合经济高质量发展之间关系的正向调节效应。 相似文献
669.
670.
Glycosylation of 2-O-acyl fructopyranosides was investigated, which were shown to be effective glycosyl donors for d-fructopyranoside synthesis with good β-selectivity and yields. For bulky acceptor 4e, α-anomer 5e was obtained with α/β = 65:23. Unexpected ring-opening was observed during acetylation of 9, indicating the sensitivity of the fructopyranosyl ring. 相似文献