全文获取类型
收费全文 | 761篇 |
免费 | 35篇 |
国内免费 | 2篇 |
专业分类
化学 | 409篇 |
晶体学 | 18篇 |
力学 | 26篇 |
数学 | 194篇 |
物理学 | 151篇 |
出版年
2023年 | 11篇 |
2022年 | 26篇 |
2021年 | 30篇 |
2020年 | 29篇 |
2019年 | 33篇 |
2018年 | 29篇 |
2017年 | 23篇 |
2016年 | 42篇 |
2015年 | 25篇 |
2014年 | 30篇 |
2013年 | 48篇 |
2012年 | 36篇 |
2011年 | 38篇 |
2010年 | 34篇 |
2009年 | 26篇 |
2008年 | 27篇 |
2007年 | 29篇 |
2006年 | 25篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 18篇 |
2002年 | 16篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 12篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1985年 | 12篇 |
1984年 | 4篇 |
1983年 | 12篇 |
1982年 | 3篇 |
1981年 | 12篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1967年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有798条查询结果,搜索用时 8 毫秒
81.
We consider the first initial boundary-value problem for strongly parabolic systems in an infinite cylinder with nonsmooth boundary. We establish conditions for the existence of generalized solutions, an estimate for this solutions, and an estimate for the derivative of the solution. 相似文献
82.
A mixed-valence uranium(IV,VI) germanate has been synthesized under high-temperature, high-pressure hydrothermal conditions. The structure contains discrete U(IV)O(6) octahedra and U(VI)O(6) tetragonal bipyramids, which are connected by three-membered single-ring Ge(3)O(9)(6-) anions to form a three-dimensional framework with 9-ring channels. The U 4f X-ray photoelectron spectroscopy spectrum was measured to identify the valence states of the uranium. 相似文献
83.
Ngo Quang Huy Trinh Thi Bich Nguyen Van Suc 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(1):129-133
Summary The paper presents a procedure to prepare soil samples for U and Th isotope measurement by alpha-spectrometry after coprecipitation
with LaF3. In this procedure the reduction of U(VI) to U(IV) was performed by Zn metal in 4M HCl solution. The recoveries of chemical
separation equal to eU-chemistry = 78±4% for uranium and eTh-chemistry = 82±4% for thorium. Canberra alpha-spectrometer was used with PIPS detectors of A-1200-37-AM Model of 1200 mm2 active area. The counting efficiency of the measuring system equals to ecounting = 18% and the total efficiencies were eU = ecounting .eU-chemistry = 14.0±0.7% for uranium and eTh = ecounting .eTh-chemistry = 14.7±0.7% for thorium. The recoveries of chemical separation were rather high (about 80%), that leads to the use of a small
weight of soil sample (about 0.5 g). The efficiencies were also stable, that allows analyzing the soil sample without using
radiotracers. They are advantages of the sample preparation procedure of this work. 相似文献
84.
This work is a continuation of [7]. In that paper, a sufficient condition was given on a real analytic fmlction g defined near 0 in C so that the algebra generated by z2 and g2 is dense in the space of continuous functions on D for all disks D close enough to the origin in C. By using the same methods and some ideas taken from the first named author's thesis we deal with the case where g is only of class C1 near 0. 相似文献
85.
Dang Ngoc Quang Marc Stadler Jacques Fournier Toshihiro Hashimoto 《Tetrahedron》2006,62(26):6349-6354
Four azaphilones named cohaerins C-F, along with 4,5,4′,5′-tetrahydroxy-1,1′-binaphthyl were isolated from the methanolic extract of the stromata of Annulohypoxylon cohaerens (Ascomycetes, Xylariaceae). Cohaerins C-E constitute typical azaphilones, bearing a γ-lactone ring, while cohaerin F has an unprecedented carbon skeleton, lacking the lactone ring of the azaphilones and with an aliphatic side chain being attached directly to the azaphilone backbone by a C-C bond. Their structures were determined by 2D NMR, IR, UV, and CD spectroscopy. They showed moderate inhibitory activity of nitric oxide production in RAW cells, and strong and nonselective antimicrobial effects. 相似文献
86.
The aim of this note is to give a new proof and some improvements of Theorem 2.1 of Ref. 1, which plays an important role in deriving various optimality conditions. 相似文献
87.
88.
In this paper p-adic analogs of the Lichtenbaum Conjectures are proven for abelian number fields F and odd prime numbers p, which generalize Leopoldt's p-adic class number formula, and express special values of p-adic L-functions in terms of orders of K-groups and higher p-adic regulators. The approach uses syntomic regulator maps, which are the p-adic equivalent of the Beilinson regulator maps. They can be compared with étale regulators via the Fontaine-Messing map,
and computations of Bloch-Kato in the case that p is unramified in F lead to results about generalized Coates-Wiles homomorphisms and cyclotomic characters.
Oblatum 14-V-96 & 9-X-97 相似文献
89.
90.
Dominique Adamski-Medda Quang Trong Nguyen Edith Dellacherie 《Journal of membrane science》1981,9(3):337-342
When a protein is exposed to a ligand linked to a water soluble polymer, a macrocomplex can be formed that can be isolated from the contaminant medium by different methods such as affinity partitioning or gel filtration. Ultrafiltration technique has also been tested in the separation of trypsin and chymotrypsin using a high molecular weight dextran—p-aminobenzamidine as a macroligand. Some theoretical considerations are given in order to evaluate the performance that can be expected from this biospecific complexation—ultrafiltration technique in the separation of biological species. 相似文献