全文获取类型
收费全文 | 1626篇 |
免费 | 83篇 |
国内免费 | 25篇 |
专业分类
化学 | 1183篇 |
晶体学 | 9篇 |
力学 | 84篇 |
数学 | 208篇 |
物理学 | 250篇 |
出版年
2023年 | 10篇 |
2022年 | 35篇 |
2021年 | 84篇 |
2020年 | 60篇 |
2019年 | 74篇 |
2018年 | 86篇 |
2017年 | 52篇 |
2016年 | 86篇 |
2015年 | 68篇 |
2014年 | 103篇 |
2013年 | 174篇 |
2012年 | 138篇 |
2011年 | 136篇 |
2010年 | 96篇 |
2009年 | 80篇 |
2008年 | 73篇 |
2007年 | 74篇 |
2006年 | 56篇 |
2005年 | 51篇 |
2004年 | 26篇 |
2003年 | 21篇 |
2002年 | 16篇 |
2001年 | 11篇 |
2000年 | 17篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1968年 | 2篇 |
1936年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有1734条查询结果,搜索用时 531 毫秒
921.
922.
923.
Seyed Jamal Tabatabaei Rezaei Khadijeh Norouzi Ali Hesami Asemeh Mashhadi Malekzadeh Ali Ramazani Vahid Amani Roya Ahmadi 《应用有机金属化学》2018,32(4)
A novel pH‐responsive magnetic nanogels were developed with the aim of targeted delivering and simultaneously releasing of newly synthesized Au(III)‐based anticancer drug, Au(1,7‐Phen)Br3. The obtained nanogels were characterized by FT‐IR, DLS, EDAX, TEM, XRD, ICP‐Ms and MRI. The TEM images showed that the nanogels had a spherical shape with a mean diameter of 20 nm. The in vitro release studies of Au (III)‐loaded nanogels showed a pH‐triggered controlled release of drugs. The in vitro cytotoxicity assay of samples to human cervical cancer HeLa cell lines indicated that the Au(III)‐loaded magnetic nanogels exert higher cytotoxicity in comparison with free Au(III) complex. Fluorescent microscope images indicated that these magnetic nanogels possessed notable cell specific targeting in vitro in the presence of an external magnetic field. The results show that this superparamagnetic nanocarrier is a promising candidate for inhibiting growth of tumor cells. 相似文献
924.
925.
Novel Cu 2+ and Fe 3+ chelates derived from L 1 were synthesized and characterized by single crystal X‐ray diffraction. The results indicate that the Fe (III) crystal, [Fe(L1‐H)Cl2], has an orthorhombic structure of the type pc2b while the dimeric Cu (II) crystal, [Cu(L1‐H)Cl … ClCu(L1‐H)], has a monoclinic with space group Cc. X‐ray diffraction and spectroscopic studies revealed that L 1 acts as monobasic tetradentate with octahedral geometry in Fe (III) crystal while it behaves as dibasic tetradentate with distorted‐octahedral in the Cu (II) crystal. Also, the two chelates were characterized by spectral, magnetic and thermal analyses. DFT parameters were used to prove the liberation of a proton from COOH rather than NH groups. The kinetic and thermodynamic parameters of Fe (III) chelate were determined by Coats‐Redfern and Horowitz‐Metzger methods. Cyclic voltammogram provides information about the oxidation states of Cu (II) and Fe (III) chelates. Antitumor activity against Epitheliod carcinoma (Hela), breast cancer (MCF‐7) and antibacterial activities of chelates were investigated. 相似文献
926.
Rabie Abdelrahman M. Abukhadra Mostafa R. Rady Ahmed M. Ahmed Sayed A. Labena Ahmed Mohamed Hussein S. H. Betiha Mohamed A. Shim Jae-Jin 《Research on Chemical Intermediates》2020,46(3):1955-1973
Research on Chemical Intermediates - Nano-ZnO and Co–ZnO supported algae (Sargassum species) were synthesized as a novel composite of promising photocatalytic activities in decolorization of... 相似文献
927.
928.
In this paper, a multi-robot formation control is designed based on Sliding Mode Control (SMC) technique. Although the structure and sensing capabilities of each robot are very simple, complex formation behaviors emerge from cooperation among them. We use an adaptive fuzzy approximator, in which unknown dynamic of robots and time delays are approximated precisely. Then it is shown that autonomous robots are able to form geometrical formations, even in the case of time-delayed dynamics, and presence of obstacles. Various simulation results and comparisons with existing works are provided that demonstrate performing efficient formation of unknown robots, with robust characteristics. 相似文献
929.
Investigation of flow and heat transfer of nanofluid in microchannel with variable property approach
Laminar flow and heat transfer of water-Al2O3 nanofluid under constant heat flux have been investigated numerically. Single-phase with temperature dependant effective properties has been assumed for fluid. Enhancement in heat transfer and increase in friction factor have been obtained by the use of nanofluid. Heat transfer enhancement is more obvious by the use of variable properties. Also, effects of temperature variation on nanofluid heat transfer are greater than the pure water. 相似文献
930.