全文获取类型
收费全文 | 1535篇 |
免费 | 44篇 |
国内免费 | 21篇 |
专业分类
化学 | 878篇 |
晶体学 | 6篇 |
力学 | 32篇 |
数学 | 249篇 |
物理学 | 435篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 24篇 |
2019年 | 27篇 |
2018年 | 16篇 |
2017年 | 13篇 |
2016年 | 40篇 |
2015年 | 35篇 |
2014年 | 38篇 |
2013年 | 65篇 |
2012年 | 83篇 |
2011年 | 82篇 |
2010年 | 50篇 |
2009年 | 52篇 |
2008年 | 82篇 |
2007年 | 86篇 |
2006年 | 91篇 |
2005年 | 60篇 |
2004年 | 74篇 |
2003年 | 62篇 |
2002年 | 58篇 |
2001年 | 37篇 |
2000年 | 22篇 |
1999年 | 29篇 |
1998年 | 20篇 |
1997年 | 15篇 |
1996年 | 42篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 25篇 |
1992年 | 27篇 |
1991年 | 31篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 7篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 17篇 |
1977年 | 11篇 |
1976年 | 5篇 |
1975年 | 12篇 |
1974年 | 13篇 |
1973年 | 11篇 |
1971年 | 5篇 |
排序方式: 共有1600条查询结果,搜索用时 31 毫秒
1.
Greg Orosi 《商业与工业应用随机模型》2015,31(4):515-527
In this work, we suggest a novel quadratic programming‐based algorithm to generate an arbitrage‐free call option surface. The empirical performance of the proposed method is evaluated using S&P 500 Index call options. Our results indicate that the proposed method provides a more precise fit to observed option prices than other alternative methodologies. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
2.
Analytical and Bioanalytical Chemistry - 相似文献
3.
R. Hefelmann P. Mann A. Aignan F. Filsinger und H. Amsel 《Fresenius' Journal of Analytical Chemistry》1902,41(1):66-68
Ohne Zusammenfassung 相似文献
4.
Intensity-dependent absorption of 25 ns excimer laser pulses in common UV-window materials was investigated. By employing a calorimetric technique which provides greatly enhanced sensitivity compared to transmissive measurements, two-photon absorption coefficients were determined at intensities of 2–80 MW/cm2 and found to be in good agreement with previous measurements at 10–100 GW/cm2. Also, color-center formation in fused silica was observed. It was possible to quantify transient and cumulative effects as a function of intensity. 相似文献
5.
Peroxyoxalate chemiluminescence may be used for sensitive postcolumn detection of phenothiazine analytes separated by high performance liquid chromatography with appropriate optimization of measurement conditions such as solvent, pH and oxalate ester. Detectability of fluorescent analytes by chemical excitation varies greatly, but analytes with low oxidation potentials are generally more readily detected at low levels, as demonstrated for phenothiazines, an important class of fluorescent drugs. Some improvement in detection limits is observed for fluphenazine when chemiluminescence detection is compared to conventional fluorescence detection. Because of the specificity of chemical excitation, fewer interferences from fluorescent impurities in a urine matrix are observed. 相似文献
6.
Consider a semigroup generated by matrices associated with an edge-coloring of a strongly connected, aperiodic digraph. We
call the semigroup Lie-solvable if the Lie algebra generated by its elements is solvable. We show that if the semigroup is
Lie-solvable then its kernel is a right group. Next, we study the Lie algebra generated by the kernel. Lie algebras generated
by two idempotents are analyzed in detail. We find that these have homomorphic images that are generalized quaternion algebras.
We show that if the kernel is not a direct product, then the Lie algebra generated by the kernel is not solvable by describing
the structure of these algebras. Finally, we discuss an infinite class of examples that are shown to always produce strongly
connected aperiodic digraphs having kernels that are not right groups. 相似文献
7.
This paper examines the performance of Commodity Trading Advisors (CTAs) using fixed and variable benchmarking models. In
order to avoid the troublesome passive and active commodity and managed futures benchmarks (indices) when examining the performance
of CTAs, we innovate by using data envelopment analysis (DEA). Because this alternative class has non-linear returns due to
long/short positions, and derivatives (i.e., dynamic trading strategies), DEA can alleviate the problems usually associated
with these indices. The effectiveness of using benchmarking models in a DEA setting will provide investors with an alternative
technique in assessing the performance and identifying efficient CTAs. 相似文献
8.
9.
Greg Gillen Albert Fahey Matt Wagner Christine Mahoney 《Applied Surface Science》2006,252(19):6537-6541
Thin monolayer and bilayer films of spin cast poly(methyl methacrylate) (PMMA), poly(2-hydroxyethyl methacrylate) (PHEMA), poly(lactic) acid (PLA) and PLA doped with several pharmaceuticals have been analyzed by dynamic SIMS using SF5+ polyatomic primary ion bombardment. Each of these systems exhibited minimal primary beam-induced degradation under cluster ion bombardment allowing molecular depth profiles to be obtained through the film. By combing secondary ion imaging with depth profiling, three-dimensional molecular image depth profiles have been obtained from these systems. In another approach, bevel cross-sections are cut in the samples with the SF5+ primary ion beam to produce a laterally magnified cross-section of the sample that does not contain the beam-induced damage that would be induced by conventional focussed ion beam (FIB) cross-sectioning. The bevel surface can then be examined using cluster SIMS imaging or other appropriate microanalysis technique. 相似文献
10.