全文获取类型
收费全文 | 88686篇 |
免费 | 16470篇 |
国内免费 | 9146篇 |
专业分类
化学 | 61245篇 |
晶体学 | 917篇 |
力学 | 5652篇 |
综合类 | 518篇 |
数学 | 10099篇 |
物理学 | 35871篇 |
出版年
2024年 | 236篇 |
2023年 | 1998篇 |
2022年 | 3246篇 |
2021年 | 3210篇 |
2020年 | 3883篇 |
2019年 | 3457篇 |
2018年 | 3093篇 |
2017年 | 2751篇 |
2016年 | 4436篇 |
2015年 | 4141篇 |
2014年 | 5096篇 |
2013年 | 6547篇 |
2012年 | 8049篇 |
2011年 | 8401篇 |
2010年 | 5554篇 |
2009年 | 5387篇 |
2008年 | 5786篇 |
2007年 | 5067篇 |
2006年 | 4766篇 |
2005年 | 3822篇 |
2004年 | 2940篇 |
2003年 | 2294篇 |
2002年 | 2109篇 |
2001年 | 1817篇 |
2000年 | 1608篇 |
1999年 | 1845篇 |
1998年 | 1595篇 |
1997年 | 1576篇 |
1996年 | 1564篇 |
1995年 | 1322篇 |
1994年 | 1151篇 |
1993年 | 996篇 |
1992年 | 858篇 |
1991年 | 783篇 |
1990年 | 643篇 |
1989年 | 501篇 |
1988年 | 370篇 |
1987年 | 308篇 |
1986年 | 323篇 |
1985年 | 261篇 |
1984年 | 151篇 |
1983年 | 117篇 |
1982年 | 100篇 |
1981年 | 57篇 |
1980年 | 42篇 |
1979年 | 10篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1957年 | 31篇 |
1922年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Xie M Liu HH Chen P Zhang ZL Wang XH Xie ZX Du YM Pan BQ Pang DW 《Chemical communications (Cambridge, England)》2005,(44):5518-5520
A simple and convenient method for the construction of CdSe/ZnS-labeled polysaccharides as bioprobes were developed, which are highly biocompatible and photostable, and have been proven to be suitable for live cell imaging. 相似文献
952.
Zhang X Grimes BA Wang JC Lacki KM Liapis AI 《Journal of colloid and interface science》2004,273(1):22-38
In this work, an analysis of the parametric sensitivity of the overshoot in the concentration of the adsorbate in the adsorbed phase, which occurs under certain conditions during an ion-exchange adsorption process, is presented and used to suggest practical implications of the concentration overshoot phenomenon on operational policies and configurations of chromatographic columns and finite bath adsorption systems. The results presented in this work demonstrate and explain how the development of an overshoot in the concentration of the adsorbate in the adsorbed phase could be enhanced or suppressed by (i) varying the diffusion coefficient, D3, of the adsorbate relative to the diffusion coefficients, D1 and D2, of the cations and anions, respectively, of the background/buffer electrolyte, (ii) altering the initial surface charge density, delta0, of the charged adsorbent particles, (iii) varying the Debye length, lambda, and (iv) changing the initial concentration, Cd3(0), of the adsorbate in the bulk liquid of the finite bath. The influence of the pH and ionic strength, Iinfinity, of the liquid solution on the development of an overshoot in the concentration of the adsorbate in the adsorbed phase is also presented and discussed through the relationships of these parameters to delta0 and lambda, respectively. Furthermore, a detailed explanation of the effects of each parameter on the interplay between the diffusive and electrophoretic molar fluxes, as well as on the structure and functioning of the electrical double layer, which are responsible for the concentration overshoot phenomenon, is presented. 相似文献
953.
954.
955.
Separation of salidroside from Rhodiola crenulata by high-speed counter-current chromatography 总被引:3,自引:0,他引:3
High-speed counter-current chromatography (HSCCC) was used to purify salidroside from an extract of Rhodiola crenulata with two steps using a two-phase solvent system composed of ethyl acetate-n-butanol-water (1:4:5, v/v) in the first run and chloroform-methanol-isopropanol-water (5:6:1:4) in the second run. The method yielded 21.9 mg of salidroside from 1.216 g of the crude sample at 98% purity determined by HPLC analyses. Identification was performed by 1H NMR, 13C NMR, and MS. 相似文献
956.
957.
958.
959.
960.