全文获取类型
收费全文 | 15396篇 |
免费 | 716篇 |
国内免费 | 145篇 |
专业分类
化学 | 10044篇 |
晶体学 | 50篇 |
力学 | 323篇 |
综合类 | 1篇 |
数学 | 2940篇 |
物理学 | 2899篇 |
出版年
2023年 | 141篇 |
2022年 | 290篇 |
2021年 | 347篇 |
2020年 | 420篇 |
2019年 | 495篇 |
2018年 | 380篇 |
2017年 | 292篇 |
2016年 | 597篇 |
2015年 | 565篇 |
2014年 | 549篇 |
2013年 | 914篇 |
2012年 | 1078篇 |
2011年 | 1276篇 |
2010年 | 677篇 |
2009年 | 563篇 |
2008年 | 908篇 |
2007年 | 830篇 |
2006年 | 838篇 |
2005年 | 772篇 |
2004年 | 605篇 |
2003年 | 470篇 |
2002年 | 437篇 |
2001年 | 239篇 |
2000年 | 170篇 |
1999年 | 182篇 |
1998年 | 155篇 |
1997年 | 165篇 |
1996年 | 168篇 |
1995年 | 145篇 |
1994年 | 113篇 |
1993年 | 101篇 |
1992年 | 85篇 |
1991年 | 78篇 |
1990年 | 66篇 |
1989年 | 41篇 |
1988年 | 44篇 |
1987年 | 48篇 |
1986年 | 45篇 |
1985年 | 72篇 |
1984年 | 58篇 |
1983年 | 34篇 |
1982年 | 58篇 |
1981年 | 49篇 |
1980年 | 44篇 |
1979年 | 40篇 |
1978年 | 44篇 |
1977年 | 41篇 |
1976年 | 47篇 |
1974年 | 34篇 |
1973年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
912.
Nanoaggregation of the thermally stable bis(2-hydroxy-9(10),16(17),23(24)-tri-tert-butylphthalocyanine) of J-type was observed by the field emission scanning electron microscopy (FE-SEM). Ordered phases, represented as threads composed of about 200 nm diameter circles were discovered, unlike the parent dimeric magnesium complex, in which similar circles combine together to give visually distinguishable zones with widths of about 600 nm and the same distance between them. 相似文献
913.
Leonid Kikot Alexander Lyapunov Tatiana Bogaschenko Sergey Smola Catherine Kulygina 《合成通讯》2013,43(4):478-484
A new facile synthetic route to benzils containing fragments of 12-crown-4, 15-crown-5, and 18-crown-6 by oxidation of corresponding stilbenes was developed. The first representative of a new family of fluorescent sensors was obtained by reaction of bis(15-crown-5)benzil with o-phenylenediamine. The latter exhibits great fluorescence enhancement upon association with K+ and Rb+ compared to Na+ and Cs+. 相似文献
914.
Mladenova Emiliya Burdin Blagoy Milchev Alexander 《Journal of Solid State Electrochemistry》2017,21(6):1567-1569
Journal of Solid State Electrochemistry - Kinetics of electrochemical nucleation and growth of three-dimensional clusters on a foreign substrate are considered in case of multi- and single-step ion... 相似文献
915.
Namiq G. Shikhaliyev Abel M. Maharramov Khanim N. Bagirova Gulnar T. Suleymanova Biligma D. Tsyrenova Valentine G. Nenajdenko Alexander S. Novikov Victor N. Khrustalev Alexander G. Tskhovrebov 《Mendeleev Communications》2021,31(2):191-193
- Download : Download high-res image (143KB)
- Download : Download full-size image
916.
Stephen Lane Bernadette C. Proemse Alexander Tennant Michael E. Wieser 《Analytical and bioanalytical chemistry》2013,405(9):2957-2963
Here, we report the first measurements of the molybdenum (Mo) isotopic composition of aerosols collected on Teflon air filters. Mo concentrations and isotopic compositions were measured at selected locations in the city of Calgary, Canada, including a residence, the isotope laboratory at the University of Calgary, the University of Calgary weather station, and the City of Calgary Transit bus garage. Concentrations ranged from 0.07 ng/m3 in the laboratory to 19.0 ng/m3 in the bus garage. The concentrations of Mo in the air samples collected in the bus garage were the highest measured in this study. To date, there are no reported data for the Mo isotopic composition of airborne Mo. In this study, the δ98/95Mo values measured for the different urban sampling sites and reported relative to SRM 3134, ranged from ?0.18 to +0.94 ‰. The results of this investigation suggest that measurements of Mo concentrations and isotopic compositions have the potential to trace anthropogenic emissions in an urban environment. 相似文献
917.
Improvements for ground-based remote sensing of atmospheric aerosol properties by additional polarimetric measurements 总被引:1,自引:0,他引:1
Zhengqiang Li Philippe Goloub Oleg Dubovik Luc Blarel Wenxing Zhang Thierry Podvin Alexander Sinyuk Mikhail Sorokin Hongbin Chen Brent Holben Didier Tanr Marius Canini Jean-Pierre Buis 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(17):1954-1961
We discuss the improvements in the aerosol properties characterization resulting from the additional multi-wavelength polarization measurements measured by a new CIMEL polarized sun/sky-photometer, CE318-DP. In order to process direct-sun, sky and polarization measurements in a wide spectral range (340–1640 nm), we developed new calibration methods and strategies, e.g. using the Langley plot method to calibrate both direct-sun irradiance and sky radiance, as well as combining laboratory facilities with a vicarious method to calibrate the polarized sky measurements. For studying the impact of new polarimetric measurements on the retrievals of aerosol properties, we have processed an extensive record of field measurements using an updated Dubovik and King retrieval algorithm [Dubovik O, Sinyuk A, Lapyonok T, Holben BN, Mishchenko MI, et al. Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust. J Geophys Res 2006;111:D11208.]. A preliminary analysis shows that adding polarization in the inversion can reduce possible errors (notably for about 30% of our field cases) in the fine mode size distribution, real part of refractive index and particle shape parameter retrievals, especially for small particles. 相似文献
918.
919.
920.