全文获取类型
收费全文 | 2871篇 |
免费 | 106篇 |
国内免费 | 21篇 |
专业分类
化学 | 2079篇 |
晶体学 | 14篇 |
力学 | 92篇 |
数学 | 427篇 |
物理学 | 386篇 |
出版年
2023年 | 29篇 |
2022年 | 41篇 |
2021年 | 64篇 |
2020年 | 68篇 |
2019年 | 74篇 |
2018年 | 45篇 |
2017年 | 60篇 |
2016年 | 101篇 |
2015年 | 97篇 |
2014年 | 95篇 |
2013年 | 158篇 |
2012年 | 198篇 |
2011年 | 194篇 |
2010年 | 142篇 |
2009年 | 112篇 |
2008年 | 150篇 |
2007年 | 164篇 |
2006年 | 119篇 |
2005年 | 105篇 |
2004年 | 61篇 |
2003年 | 59篇 |
2002年 | 54篇 |
2001年 | 41篇 |
2000年 | 38篇 |
1999年 | 33篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 37篇 |
1995年 | 26篇 |
1994年 | 28篇 |
1993年 | 19篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 15篇 |
1987年 | 22篇 |
1986年 | 15篇 |
1985年 | 21篇 |
1983年 | 19篇 |
1982年 | 25篇 |
1981年 | 20篇 |
1980年 | 23篇 |
1979年 | 20篇 |
1978年 | 25篇 |
1977年 | 19篇 |
1976年 | 16篇 |
1975年 | 15篇 |
1974年 | 25篇 |
1973年 | 24篇 |
1970年 | 15篇 |
排序方式: 共有2998条查询结果,搜索用时 15 毫秒
1.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
2.
3.
4.
In this note we show how coverings induced by voltage assignments can be used to produce packings of disjoint copies of the Hoffman‐Singleton graph into K50. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 408–412, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10049 相似文献
5.
We introduce extensions of the Mangasarian-Fromovitz and Abadie constraint qualifications to nonsmooth optimization problems with feasibility given by means of lower-level sets. We do not assume directional differentiability, but only upper semicontinuity of the defining functions. By deriving and reviewing primal first-order optimality conditions for nonsmooth problems, we motivate the formulations of the constraint qualifications. Then, we study their interrelation, and we show how they are related to the Slater condition for nonsmooth convex problems, to nonsmooth reverse-convex problems, to the stability of parametric feasible set mappings, and to alternative theorems for the derivation of dual first-order optimality conditions.In the literature on general semi-infinite programming problems, a number of formally different extensions of the Mangasarian-Fromovitz constraint qualification have been introduced recently under different structural assumptions. We show that all these extensions are unified by the constraint qualification presented here. 相似文献
6.
On‐line coupling of LC and ICP‐MS has been used for fractionation and detection of species of Cu, Fe, I, Se and Zn in human serum. It has been shown that anion exchange chromatography provided better separation capability (both intra‐ and inter‐element) than size‐exclusion chromatography. The mobile phases for ion exchange chromatography consisted of Tris–HNO3 buffer and ammonium salt (nitrate, acetate or formate). Formate was found to be the best mobile phase counter ion, enabling good chromatographic separation, and is acceptable for mass spectrometry too. The quantitative evaluation of element concentrations adhering to individual fractions was performed by the peak area normalization method. The repeatability of results ranged from 3 to 15% (depending on the element concentration level) and represented the main part of the result uncertainty. The accuracy of Cu and Zn fraction determinations was confirmed by comparison with the isotope dilution technique. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
7.
In the present Note, we study the asymptotic behavior of the distribution density of the stock price process in the Hull–White model. The leading terms in the asymptotic expansions at zero and infinity are found for such a density and the corresponding error estimates are given. Similar problems are solved for time averages of the volatility process, which are also of interest in the study of Asian options. To cite this article: A. Gulisashvili, E.M. Stein, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
8.
A new consistency measure, the harmonic consistency index, is obtained for any positive reciprocal matrix in the analytic hierarchy process. We show how this index varies with changes in any matrix element. A tight upper bound is provided for this new consistency measure when the entries of matrix are at most 9, as is often recommended. Using simulation, the harmonic consistency index is shown to give numerical values similar to the standard consistency index but it is easier to compute and interpret. In addition, new properties of the column sums of reciprocal matrices are obtained. 相似文献
9.
D. Chiladze J. Carbonell S. Dymov V. Glagolev M. Hartmann V. Hejny A. Kacharava I. Keshelashvili A. Khoukaz H.R. Koch V. Komarov P. Kulessa A. Kulikov G. Macharashvili Y. Maeda T. Mersmann S. Merzliakov S. Mikirtytchiants A. Mussgiller M. Nioradze H. Ohm F. Rathmann R. Schleichert H.J. Stein H. Ströher Yu. Uzikov S. Yaschenko C. Wilkin 《Physics letters. [Part B]》2006
10.
K. Stein und F. Umland 《Fresenius' Journal of Analytical Chemistry》1986,323(2):176-177
Ohne Zusammenfassung
Wir danken dem Fonds der Chemischen Industrie für finanzielle Unterstützung. 相似文献
Trace analysis of lead, cadmium and manganese in honey and sugar
Wir danken dem Fonds der Chemischen Industrie für finanzielle Unterstützung. 相似文献