全文获取类型
收费全文 | 9055篇 |
免费 | 1708篇 |
国内免费 | 947篇 |
专业分类
化学 | 6073篇 |
晶体学 | 87篇 |
力学 | 735篇 |
综合类 | 67篇 |
数学 | 1136篇 |
物理学 | 3612篇 |
出版年
2024年 | 39篇 |
2023年 | 185篇 |
2022年 | 313篇 |
2021年 | 345篇 |
2020年 | 358篇 |
2019年 | 330篇 |
2018年 | 299篇 |
2017年 | 298篇 |
2016年 | 440篇 |
2015年 | 431篇 |
2014年 | 473篇 |
2013年 | 650篇 |
2012年 | 771篇 |
2011年 | 845篇 |
2010年 | 560篇 |
2009年 | 541篇 |
2008年 | 627篇 |
2007年 | 489篇 |
2006年 | 527篇 |
2005年 | 394篇 |
2004年 | 323篇 |
2003年 | 256篇 |
2002年 | 237篇 |
2001年 | 201篇 |
2000年 | 192篇 |
1999年 | 191篇 |
1998年 | 185篇 |
1997年 | 175篇 |
1996年 | 171篇 |
1995年 | 137篇 |
1994年 | 121篇 |
1993年 | 113篇 |
1992年 | 91篇 |
1991年 | 69篇 |
1990年 | 75篇 |
1989年 | 61篇 |
1988年 | 44篇 |
1987年 | 34篇 |
1986年 | 34篇 |
1985年 | 22篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1959年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
931.
932.
A multicompartment electrolyzer, which has been used for preparative electrophoresis [Z. Liu, Z. Huang, J.-Y. Cong, et al., Sep. Sci. Technol. 31 (1996) 427], is applied for carrying out affinity chromatography in an alternating electric field. The effect of electric field strength on the adsorption and desorption characteristics is experimentally examined with human serum albumin and Blue Sepharose Fast Flow as a model system. It is shown that the existence of an electric field leads to a significant change in the adsorption capacity of the blue dye, which may be used for establishing a preferential adsorption to achieve a high resolution. The adsorption speed increases slightly with respect to the increase of electric field strength, while adsorption capacity in the presence of an electric field is independent of the electric field strength. Different elution behavior is observed as function of adsorption condition and a high recovery of the adsorbed protein is obtained when the adsorption is carried out in the presence of an electric field. 相似文献
933.
R. Bernabei P. Belli F. Montecchia W. Di Nicolantonio G. Ignesti A. Incicchitti D. Prosperi C. J. Dai L. K. Ding H. H. Kuang J. M. Ma 《Physics letters. [Part B]》1999,450(4):40
The results achieved with a statistics of 14962 kg·day, collected with the large mass highly radiopure DAMA NaI(Tl) set-up, are described and investigated in terms of WIMP annual modulation signature. A maximum likelihood analysis of these data, combined with the statistics of 4549 kg·day previously published (total statistics of 19511 kg·day), favours the hypothesis of presence of an annual modulation at 99.6% C.L. 相似文献
934.
Recently, we proposed a new transformation between the angle of canonical coordinates and the bond angle to describe the bending motion in Potential Energy Surfaces (PES) of bent triatomic molecules. In this work we extend the transformation to include linear triatomic molecules. Results for the linear triatomic molecule N2O are reported. 相似文献
935.
936.
937.
Kai Li Li Ding Zhong‐Lin Yang E‐Hu Liu Lian‐Wen Qi Ping Li Yu‐Zhu Hu 《Biomedical chromatography : BMC》2010,24(5):550-555
Asperosaponin VI (also named akebia saponin D) is a typical bioactive triterpenoid saponin isolated from the rhizome of Dipsacus asper Wall (Dipsacaceae). In this work, a sensitive high‐performance liquid chromatography–electrospray ionization–mass spectrometry (HPLC‐ESI‐MS) assay has been established for determination of asperosaponin VI in rat plasma. With losartan as the internal standard (IS), plasma samples were prepared by protein precipitation with methanol. Chromatographic separation was performed on a C18 column with a mobile phase of 10 mm ammonium acetate buffer containing 0.05% formic acid–methanol (32 : 68, v/v). The analysis was performed on an ESI in the selected ion monitoring mode using target ions at m/z 951.4 for asperosaponin VI and m/z 423.2 for the IS. The calibration curve was linear over the range 3–1000 ng/mL and the lower limit of quantification was 3.0 ng/mL. The intra‐ and inter‐assay variability values were less than 9.5 and 7.8%, respectively. The accuracies determined at the concentrations of 3.0, 100.0, 300.0 and 1000 ng/mL for asperosaponin VI were within ±15.0%. The validated method was successfully applied to a pharmacokinetic study in rats after oral administration of asperosaponin VI. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
938.
We investigate the buckling under compression of a slender beam with a distributed lateral elastic support, for which there is an associated cost. For a given cost, we study the optimal choice of support to protect against Euler buckling. We show that with only weak lateral support, the optimum distribution is a delta-function at the centre of the beam. When more support is allowed, we find numerically that the optimal distribution undergoes a series of bifurcations. We obtain analytical expressions for the buckling load around the first bifurcation point and corresponding expansions for the optimal position of support. Our theoretical predictions, including the critical exponent of the bifurcation, are confirmed by computer simulations. 相似文献
939.
940.
<正>As potential building blocks for micro-nano devices,one-dimensional semiconductor nanowires(NWs)have been widely studied in recent decades.Due to limited dimension and large surface-to-volume ratio,devices based on NWs are more likely to exhibit unique properties.NW photodetectors adopting different materials have been fabricated.However,the performance is greatly affected by several issues such as lattice quality,surface homogeneity,contact electrodes and 相似文献