全文获取类型
收费全文 | 28313篇 |
免费 | 4550篇 |
国内免费 | 3304篇 |
专业分类
化学 | 20074篇 |
晶体学 | 302篇 |
力学 | 1708篇 |
综合类 | 170篇 |
数学 | 3081篇 |
物理学 | 10832篇 |
出版年
2024年 | 125篇 |
2023年 | 655篇 |
2022年 | 1026篇 |
2021年 | 1132篇 |
2020年 | 1151篇 |
2019年 | 1165篇 |
2018年 | 1033篇 |
2017年 | 960篇 |
2016年 | 1396篇 |
2015年 | 1365篇 |
2014年 | 1590篇 |
2013年 | 2075篇 |
2012年 | 2449篇 |
2011年 | 2407篇 |
2010年 | 1684篇 |
2009年 | 1548篇 |
2008年 | 1792篇 |
2007年 | 1601篇 |
2006年 | 1473篇 |
2005年 | 1237篇 |
2004年 | 963篇 |
2003年 | 784篇 |
2002年 | 807篇 |
2001年 | 601篇 |
2000年 | 548篇 |
1999年 | 676篇 |
1998年 | 521篇 |
1997年 | 461篇 |
1996年 | 456篇 |
1995年 | 400篇 |
1994年 | 320篇 |
1993年 | 304篇 |
1992年 | 242篇 |
1991年 | 218篇 |
1990年 | 232篇 |
1989年 | 169篇 |
1988年 | 118篇 |
1987年 | 90篇 |
1986年 | 79篇 |
1985年 | 90篇 |
1984年 | 50篇 |
1983年 | 44篇 |
1982年 | 42篇 |
1981年 | 25篇 |
1980年 | 14篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1957年 | 5篇 |
1916年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
Integrable systems of NLS type in 2+1 dimensions are studied in three ways: their special solutions by Lie point symmetries, breaking-solutions by the ISM, as well as the non-isospectral problems.Department of Mathematics, Statistics and Computing Science, University of New England, Armidale N.S.W. 2351, Australia. E-mail: zhuhan@neumann.une.edu.au, xhe@metz.une.edu.au Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 99, No. 3, pp. 382–389, June, 1994. 相似文献
33.
34.
35.
LIZHIBIN SHIHE 《高校应用数学学报(英文版)》1996,11(1):1-6
Abstract. We consider the following simplified model for the Belousou-Zhabotinskii(B-Z)reaction: 相似文献
36.
37.
A new self-assembled and highly oriented one-dimensional single-crystal nanostructure of WO3 with hexagonal form was successfully prepared by a mild, solution-based colloidal approach. 相似文献
38.
39.
40.
On-line photochemical reaction of reserpine in the presence of acetone was investigated. Acetone was found to speed up the on-line photochemical conversion of reserpine into an intensively fluorescent compound. Not only reaction acidity but also the acetate buffer concentration affected the on-line photochemical induced fluorescence signal. Based on the observation an automated flow injection photochemical fluorimetric approach was developed. An injected sample zone was carried by a water stream to be merged with a acetate buffer (pH 3.4) solution containing 0.02% acetone in a knotted PTFE reactor (KR), which was freely coiled around a 6-W low pressure mercury lamp. While passing the KR, reserpine was transformed into an intensively fluorescent compound. It was on-line detected in a flow-through cell at the emission wavelength of 490 nm and excitation wavelength of 386 nm. At optimized conditions, a detection limit 0.45 mug l(-1) was achieved at a sampling rate of 90 h(-1). Eleven determinations of a 0.5 mg l(-1) reserpine standard solution gave a R.S.D. of 0.3%. The linear dynamic range of reserpine calibration curve was 0.01-0.75 mg l(-1). The proposed method was applied to assay the reserpine content in tablets and to monitor the dissolution profile of reserpine tablets. Satisfactory results were obtained for both the assays and dissolution studies. 相似文献