全文获取类型
收费全文 | 11158篇 |
免费 | 1937篇 |
国内免费 | 1325篇 |
专业分类
化学 | 8051篇 |
晶体学 | 68篇 |
力学 | 699篇 |
综合类 | 86篇 |
数学 | 1119篇 |
物理学 | 4397篇 |
出版年
2024年 | 44篇 |
2023年 | 286篇 |
2022年 | 412篇 |
2021年 | 463篇 |
2020年 | 501篇 |
2019年 | 445篇 |
2018年 | 364篇 |
2017年 | 319篇 |
2016年 | 545篇 |
2015年 | 490篇 |
2014年 | 595篇 |
2013年 | 839篇 |
2012年 | 1036篇 |
2011年 | 993篇 |
2010年 | 660篇 |
2009年 | 663篇 |
2008年 | 738篇 |
2007年 | 640篇 |
2006年 | 576篇 |
2005年 | 495篇 |
2004年 | 373篇 |
2003年 | 338篇 |
2002年 | 282篇 |
2001年 | 230篇 |
2000年 | 222篇 |
1999年 | 263篇 |
1998年 | 218篇 |
1997年 | 196篇 |
1996年 | 209篇 |
1995年 | 177篇 |
1994年 | 147篇 |
1993年 | 125篇 |
1992年 | 109篇 |
1991年 | 79篇 |
1990年 | 84篇 |
1989年 | 56篇 |
1988年 | 50篇 |
1987年 | 45篇 |
1986年 | 30篇 |
1985年 | 29篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1957年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Zhang Z Wang J Yuan H Gao Y Liu D Song L Xiang Y Zhao X Liu L Luo S Dou X Mou S Zhou W Xie S 《The journal of physical chemistry. B》2005,109(39):18352-18355
At a low temperature of 450 degrees C, ZnS nanoribbons have been synthesized on Si and KCl substrates by a simple chemical vapor deposition (CVD) method with a two-temperature-zone furnace. Zinc and sulfur powders are used as sources in the different temperature zones. X-ray diffraction (XRD), selected area electron diffraction (SEAD), and transmission electron microscopy (TEM) analysis show that the ZnS nanoribbons are the wurtzite structure, and there are two types-single-crystal and bicrystal nanoribbons. Photoluminescence (PL) spectrum shows that the spectrum mainly includes two parts: a purple emission band centering at about 390 nm and a blue emission band centering at about 445 nm with a weak green shoulder around 510 nm. 相似文献
92.
X. Y. Li G. J. Wang J. G. Sun Y. T. Zheng B. Yan H. T. Xie X. Wang 《Chromatographia》2007,65(1-2):13-18
To support preclinical pharmacokinetic investigation of 1-[4-[2-(4-bromobenzene-sulfonaminoethyl)phenylsufonyl]-3-(trans-4-methylcyclohexyl)urea
(G004), a rapid, sensitive and specific high-performance liquid chromatography–electrospray ionization mass spectrometry (LC–ESI-MS)
method was developed and validated. Glibenclamide was employed as internal standard. After liquid–liquid extraction the analyte
was analyzed on a Kromasil C18 column (150 × 2.0 mm i.d.) with a mobile phase consisted of acetonitrile–water (0.05% acetic acid), 30:70 (v/v). The flow
rate was 0.2 mL min−1. Detection was performed on a quadrupole mass spectrometer using an electrospray ionization interface and the selected-ion
monitoring (SIM) mode. The retention time was about 3.5 and 4.2 min for Glibenclamide and G004, respectively. The assay was
linear over the concentration range of 2.0–500.0 ng mL−1. Extraction Recovery of G004 in rat plasma was more than 87%. The intra- and inter-assay precision was lower than 11.5% (CV).
This validated method was successfully applied to the pharmacokinetics of G004 in rats. 相似文献
93.
94.
95.
96.
Estimation of an important constant in sieve method 总被引:1,自引:0,他引:1
Xie Sheng-gang 《数学学报(英文版)》1994,10(1):1-3
ζ
k
is one of the most important constant in the sieve methods. This paper gives the relatively accurate lower bound and upper
bound on it, that is,
, wherec=1.22... andk>16. 相似文献
97.
98.
99.
100.
Xie Z Sielemann S Schmidt H Li F Baumbach JI 《Analytical and bioanalytical chemistry》2002,372(5-6):606-610
A combination of a custom-designed ion mobility spectrometer (IMS) with a UV ionization source and a high speed capillary column (HSCC) has been developed as an analytical device for the sensitive detection of volatile organic compounds (VOCs), e.g. 2-propanone (acetone), 2-butanone and 3-pentanone (diethyl ketone) in the gas phase. A fast separation of the three selected substances and benzene, toluene and m-xylene (BTX) - all of which occur in human breath - has been achieved within less than four minutes at a carrier gas flow rate of 4.5 mL x min(-1). Multi-dimensional correlations presented support the interpretation of the acquired spectra of mixtures. Method detection limits were 2.7 microg x L(-1) for acetone and 2-butanone and 3.0 microg x L(-1) for diethyl ketone in nitrogen, respectively. The assay linear dynamic range is 4-320 microg x L(-1). 相似文献