全文获取类型
收费全文 | 7373篇 |
免费 | 414篇 |
国内免费 | 188篇 |
专业分类
化学 | 4521篇 |
晶体学 | 86篇 |
力学 | 313篇 |
综合类 | 25篇 |
数学 | 1097篇 |
物理学 | 1933篇 |
出版年
2023年 | 68篇 |
2022年 | 138篇 |
2021年 | 175篇 |
2020年 | 195篇 |
2019年 | 197篇 |
2018年 | 175篇 |
2017年 | 149篇 |
2016年 | 230篇 |
2015年 | 227篇 |
2014年 | 258篇 |
2013年 | 514篇 |
2012年 | 460篇 |
2011年 | 510篇 |
2010年 | 317篇 |
2009年 | 294篇 |
2008年 | 374篇 |
2007年 | 316篇 |
2006年 | 322篇 |
2005年 | 277篇 |
2004年 | 216篇 |
2003年 | 220篇 |
2002年 | 202篇 |
2001年 | 164篇 |
2000年 | 144篇 |
1999年 | 113篇 |
1998年 | 67篇 |
1997年 | 70篇 |
1996年 | 75篇 |
1995年 | 55篇 |
1994年 | 94篇 |
1993年 | 70篇 |
1992年 | 80篇 |
1991年 | 65篇 |
1990年 | 57篇 |
1989年 | 48篇 |
1988年 | 49篇 |
1987年 | 43篇 |
1986年 | 46篇 |
1985年 | 71篇 |
1984年 | 68篇 |
1983年 | 43篇 |
1982年 | 67篇 |
1981年 | 56篇 |
1980年 | 62篇 |
1979年 | 55篇 |
1978年 | 62篇 |
1977年 | 56篇 |
1976年 | 48篇 |
1974年 | 38篇 |
1973年 | 44篇 |
排序方式: 共有7975条查询结果,搜索用时 46 毫秒
61.
Nicolas Le Calvez 《中国化学会会志》2002,49(4):585-592
The aim of this study was to develop an analytical method to determine the organochlorine concentrations in sediments. Combination of Microwave assisted Solvent Extraction (MASE) and capillary gas chromatography with specific detection (electron capture detector) was a viable approach for the determination of pesticides in solid matrixes. In this study, MASE development was focused on the selection of a suitable extraction solvent for all the target analytes. MASE procedure was validated by comparison with conventional methods such as Soxhlet and sonication extraction. The proposed method was then applied to determine the organochlorine insecticides concentrations in samples from Authie Bay (France). Environmental water samples were analysed and five target analytes were detected in concentrations from 0.03 to 0.56 ng/g of dry sediment. These investigations showed the accumulation and the persistency of these products in sediments in spite of the fact they were banned a few decades ago. 相似文献
62.
63.
64.
65.
Jana Mikulova Francois Gérard Danielle Mesnard Charles Kappenstein Daniel Duprez 《Journal of solid state chemistry》2006,179(8):2511-2520
CeO2 doped with praseodymium, neodymium and/or zirconium atoms were prepared by coprecipitation and by the sol-gel method. Structural properties were investigated by in situ XRD and Raman spectroscopy while oxygen storage capacity (OSC) was measured by transient CO oxidation. All the compounds, except pure Nd2O3, have a fluorite-type structure as well as a Raman band at 560 cm−1 characteristic of the oxygen vacancies involving non-stoichiometric oxides. The lattice parameter under hydrogen, being dependent on the temperature, revealed two reduction mechanisms: one at a low temperature at the surface and another at a high temperature in the bulk. Ce-Nd binary oxides show a strong tendency towards crystallite aggregation, which reduces accessibility to gases and OSC properties. Zirconium improves the thermal resistance to sintering of both Ce-Nd and Ce-Pr oxides. The Zr-Ce-Pr-O followed by Zr-Ce-Nd-O compounds displaying high oxygen mobility at a low temperature, appear to be very promising for practical applications such as OSC materials. 相似文献
66.
Summary The existence of a joint asymptotic distribution for the windings of a three-dimensional Brownian motion around a finite number of straight lines is obtained. This complements the recent studies, by Pitman- Yor, and the authors, of the joint asymptotic distribution for the windings of planar Brownian motion around a finite number of points.The following principle governs the passage from results in the plane to results in space:Let B be a three-dimensional Brownian motion, and P
1, ..., P
k, k planes which intersect two by two. Then, the convergences in distribution concerning the planar Brownian motions B
i (1ik), defined respectively as the orthogonal projections of B on P
i (1ik), take place jointly, and the corresponding limit variables are independent. 相似文献
67.
68.
J. Kuriplach L. Lešták M. Rotter B. Sedlák M. Trhlík M. Finger T. Lešner J. Dupák P. Novák M. Vobecký 《Hyperfine Interactions》1987,34(1-4):339-342
First experimental results of160Tb nuclear orientation in yttrium single crystal matrix are described. The influence of external magnetic field in combination with the crystal field interaction is discussed. 相似文献
69.
70.
Carlier J Arscott S Thomy V Camart JC Cren-Olivé C Le Gac S 《Journal of chromatography. A》2005,1071(1-2):213-222
We report here on an integrated microfabricated device dedicated to the preparation of biological samples prior to their on-line analysis by electrospray ionization-mass spectrometry (ESI-MS). This microfluidic device is fabricated using the negative photoresist SU-8 by microtechnology techniques. The device includes a chromatographic module plus an ESI interface for MS. The chromatographic module is dedicated to sample purification and is based on a polymer monolithic phase which includes hydrophobic moieties. The ESI interface is integrated onto the chip and is based on a capillary slot. We present here the integration of these different modules onto a single system that is fabricated via a SU-8-based microtechnology route. We present also their testing for the purification of peptide samples. This started with a partial integration step with the combination of at least two of the modules (microsystem + monolith; microsystem + nib) and their test before the fabrication and testing of fully integrated microsystems. 相似文献