全文获取类型
收费全文 | 3337篇 |
免费 | 522篇 |
国内免费 | 457篇 |
专业分类
化学 | 2597篇 |
晶体学 | 72篇 |
力学 | 137篇 |
综合类 | 32篇 |
数学 | 433篇 |
物理学 | 1045篇 |
出版年
2024年 | 12篇 |
2023年 | 87篇 |
2022年 | 180篇 |
2021年 | 166篇 |
2020年 | 209篇 |
2019年 | 177篇 |
2018年 | 164篇 |
2017年 | 145篇 |
2016年 | 218篇 |
2015年 | 219篇 |
2014年 | 225篇 |
2013年 | 266篇 |
2012年 | 251篇 |
2011年 | 245篇 |
2010年 | 217篇 |
2009年 | 184篇 |
2008年 | 176篇 |
2007年 | 167篇 |
2006年 | 145篇 |
2005年 | 118篇 |
2004年 | 87篇 |
2003年 | 70篇 |
2002年 | 73篇 |
2001年 | 64篇 |
2000年 | 43篇 |
1999年 | 35篇 |
1998年 | 28篇 |
1997年 | 24篇 |
1996年 | 34篇 |
1995年 | 31篇 |
1994年 | 20篇 |
1993年 | 31篇 |
1992年 | 26篇 |
1991年 | 27篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1973年 | 6篇 |
1927年 | 3篇 |
排序方式: 共有4316条查询结果,搜索用时 31 毫秒
101.
102.
Jincheng Li Huan Liu Chaoying Wang Lidong Wu Dan Liu 《Analytical and bioanalytical chemistry》2016,408(24):6537-6544
103.
The multi-attribute grey target decision method for attribute value within three-parameter interval grey number 总被引:1,自引:0,他引:1
Based on the grey system theory and methods, the grey-target decision-making problem is discussed, in which the attribute values are grey numbers and the maximum probability of the value of grey number is known. Firstly, the optimal effect vector is the positive bull’s-eye and positive bull’s-eye distance of each scheme is defined. Subjectively or objectively weighting method is integrated to determine the index weight and integrated optimization model of index weight is established. Finally, the critical effect vector is the negative bull’s-eye and negative bull’s-eye distance of each scheme is defined, then relative bull’s-eye distance and comprehensive the bull’s-eye distance of grey target decision-making are given. An example is also presented to illustrate the usefulness and effectiveness of the methods obtained in this paper and provides a new idea for grey target decision-making method research. 相似文献
104.
As an emerging donor building block, naphthodithiophene (NDT) is causing more concerns in the field of organic semiconductors. With the rigid and coplanar molecule structure, NDT will exhibit more application space relying on its own advantage for facilitating the charge carrier transport. In this review article, we have summarized the development progress on the NDT-based donor materials for solution processed organic solar cells. Discussions and comments on those representative NDT type materials about structure and property are also presented. 相似文献
105.
Yanfeng Chu Huan Yu Yunti Zhang Guangyan Zhang Yingying Ma Renxi Zhuo Xulin Jiang 《Journal of polymer science. Part A, Polymer chemistry》2014,52(23):3346-3355
Biodegradable amphiphilic ABC Y‐shaped triblock copolymer (MPBC) containing PEG, PBLA, and PCL segments was synthesized via the combination of enzymatic ring‐opening polymerization (ROP) of epsilon‐caprolactone, ROP of BLA‐N‐carboxyanhydride and click chemistry, where PEG, PBLA, and PCL are poly(ethylene glycol), poly(benzyl‐l ‐aspartate), and polycaprolactone, respectively. Propynylamine was employed as ROP initiator for the preparation of alkynyl‐terminated PBLA and methyloxy‐PEG with hydroxyl and azide groups at the chain‐end was used as enzymatic ROP initiator for synthesis of monoazido‐midfunctionalized block copolymer mPEG‐b‐PCL. The subsequent click reaction led to the formation of Y‐shaped asymmetric heteroarm terpolymer MPBC. The polymer structures were characterized by different analyses. The MPBC terpolymer self‐assembled into micelles and physically encapsulated drug doxorubicin (DOX) to form DOX‐loaded micelles, which showed good stability and slow drug release. In vitro cytotoxicity study indicated that the MPBC micelles were nontoxic and the DOX‐loaded micelles displayed obvious anticancer activity similar to free DOX against HeLa cells. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3346–3355 相似文献
106.
107.
Due to its enormously high flexibility laser forming has been gaining importance in recent years. This rapidness and flexibility demand very precise controlling strategies especially when simulating the process of large plates and challenging the limited computation power of the current workstation. A simple, robust and accurate modeling method of laser forming has been demonstrated to solve this problem. The simplified model is meshed by multi-layered shell element, simulated with a more real scanning method and fewer parameters. The intelligent meshing strategies have reduced the number of elements dramatically. Thus the simulation efficiency has been improved significantly. By comparing the simulation results under the simplified model with the results under the traditional model for laser forming, the applicability of proposed method has been proven. The method of these simplified models is also suitable to simulate complex finite element models, which take much time to simulate. It would throw some light on the thermal mechanically coupled-field simulation of large sheet. 相似文献
108.
Wang Fei Cressault Yann Teulet Philippe Li Huan Yang Ke 《Plasma Chemistry and Plasma Processing》2019,39(4):1049-1069
Plasma Chemistry and Plasma Processing - Gas tungsten arc welding (GTAW), a widely used industrial process, is one of the most intense artificial sources of optical radiation. This paper presents a... 相似文献
109.
110.
The chemical constituents of the fungus Verticillium psalliotae were studied. Two new aromadendrane sesquiterpenes inonotin M (1) and inonotin N (2) were isolated from the EtOAc extract of the fungal culture broth. The structures of compounds were elucidated mainly by HRESIMS experiments, and 1D, 2D-NMR spectroscopy analysis. 相似文献