全文获取类型
收费全文 | 8028篇 |
免费 | 1234篇 |
国内免费 | 672篇 |
专业分类
化学 | 4161篇 |
晶体学 | 1167篇 |
力学 | 485篇 |
综合类 | 114篇 |
数学 | 1576篇 |
物理学 | 2431篇 |
出版年
2024年 | 8篇 |
2023年 | 77篇 |
2022年 | 206篇 |
2021年 | 259篇 |
2020年 | 310篇 |
2019年 | 232篇 |
2018年 | 161篇 |
2017年 | 232篇 |
2016年 | 378篇 |
2015年 | 312篇 |
2014年 | 484篇 |
2013年 | 608篇 |
2012年 | 461篇 |
2011年 | 591篇 |
2010年 | 534篇 |
2009年 | 517篇 |
2008年 | 543篇 |
2007年 | 557篇 |
2006年 | 523篇 |
2005年 | 430篇 |
2004年 | 399篇 |
2003年 | 324篇 |
2002年 | 250篇 |
2001年 | 188篇 |
2000年 | 219篇 |
1999年 | 165篇 |
1998年 | 157篇 |
1997年 | 151篇 |
1996年 | 104篇 |
1995年 | 76篇 |
1994年 | 89篇 |
1993年 | 62篇 |
1992年 | 52篇 |
1991年 | 55篇 |
1990年 | 37篇 |
1989年 | 33篇 |
1988年 | 33篇 |
1987年 | 27篇 |
1986年 | 16篇 |
1985年 | 20篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1973年 | 2篇 |
1959年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有9934条查询结果,搜索用时 31 毫秒
901.
Angela Cardelli Lucia Ricci Giacomo Ruggeri Silvia Borsacchi Marco Geppi 《European Polymer Journal》2011,(8):1589-1600
A micrometric silica modified with perylene derivative (SiO2–TES) has been prepared by hydrolysis–condensation reactions between silica and N,N’-bis-(3-triethoxysilylpropyl)-perylene-tetracarboxyldiimide (P-TES) and utilized as filler in LLDPE films together with a compatibilizer. Spectroscopic analyses on SiO2–TES confirmed the grafting of P-TES on silica, while its amount was determined by thermogravimetric analysis. Solid state NMR provided information about the structure of silicon atoms involved in the condensation of SiO2 and P-TES that resulted mainly in silicon atoms grafted with bi-dentate anchorages.UV–Vis and fluorescence analyses carried out on P-TES showed the ability of the dye to generate J-type aggregates in apolar solvents. The same analyses on SiO2–TES revealed the presence of both isolated and aggregated dye molecules grafted on silica surface, while on polymeric dispersions of SiO2–TES, they have shown only the presence of P-TES aggregates grafted to silica.Thanks to the direct correlation between optical properties (obtained both by UV–Vis and by fluorescence analyses) and the chemical environment of composites, the luminescent silica SiO2–TES could be used to estimate the filler dispersion extent in different microcomposite polymer materials. 相似文献
902.
Caragisides A–C ( 1 – 3 , resp.), three new isoflavone glucosides, were isolated from the BuOH sub‐fraction of the EtOH extract of the whole plant of Caragana conferta, along with ononoside ( 4 ), reported for the first time from this species. The structures of the new compounds were elucidated by spectroscopic techniques including MS and 2D‐NMR spectroscopy. Compounds 1 – 3 showed significant inhibition of platelet aggregation. 相似文献
903.
Shim H 《Experimental & molecular medicine》2011,43(10):539-549
To date, more than 30 antibodies have been approved worldwide for therapeutic use. While the monoclonal antibody market is rapidly growing, the clinical use of therapeutic antibodies is mostly limited to treatment of cancers and immunological disorders. Moreover, antibodies against only five targets (TNF-α, HER2, CD20, EGFR, and VEGF) account for more than 80 percent of the worldwide market of therapeutic antibodies. The shortage of novel, clinically proven targets has resulted in the development of many distinct therapeutic antibodies against a small number of proven targets, based on the premise that different antibody molecules against the same target antigen have distinct biological and clinical effects from one another. For example, four antibodies against TNF-α have been approved by the FDA -- infliximab, adalimumab, golimumab, and certolizumab pegol -- with many more in clinical and preclinical development. The situation is similar for HER2, CD20, EGFR, and VEGF, each having one or more approved antibodies and many more under development. This review discusses the different binding characteristics, mechanisms of action, and biological and clinical activities of multiple monoclonal antibodies against TNF-α, HER-2, CD20, and EGFR and provides insights into the development of therapeutic antibodies. 相似文献
904.
905.
Xia X Zeng J McDearmon B Zheng Y Li Q Xia Y 《Angewandte Chemie (International ed. in English)》2011,50(52):12542-12546
Shaped and dimpled: Silver nanocrystals enclosed by concave surfaces and thus high-index facets have been prepared by simply controlling the growth habit of Ag cubic seeds. Four types of concave nanocrystals, including octahedron, cube, octapod, and trisoctahedron, were obtained (see picture). 相似文献
906.
907.
J-aggregates: from serendipitous discovery to supramolecular engineering of functional dye materials
Würthner F Kaiser TE Saha-Möller CR 《Angewandte Chemie (International ed. in English)》2011,50(15):3376-3410
J-aggregates are of significant interest for organic materials conceived by supramolecular approaches. Their discovery in the 1930s represents one of the most important milestones in dye chemistry as well as the germination of supramolecular chemistry. The intriguing optical properties of J-aggregates (in particular, very narrow red-shifted absorption bands with respect to those of the monomer and their ability to delocalize and migrate excitons) as well as their prospect for applications have motivated scientists to become involved in this field, and numerous contributions have been published. This Review provides an overview on the J-aggregates of a broad variety of dyes (including cyanines, porphyrins, phthalocyanines, and perylene bisimides) created by using supramolecular construction principles, and discusses their optical and photophysical properties as well as their potential applications. Thus, this Review is intended to be of interest to the supramolecular, photochemistry, and materials science communities. 相似文献
908.
909.
910.