全文获取类型
收费全文 | 480篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
化学 | 367篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 76篇 |
物理学 | 62篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 22篇 |
2015年 | 19篇 |
2014年 | 17篇 |
2013年 | 27篇 |
2012年 | 27篇 |
2011年 | 38篇 |
2010年 | 13篇 |
2009年 | 20篇 |
2008年 | 21篇 |
2007年 | 37篇 |
2006年 | 32篇 |
2005年 | 22篇 |
2004年 | 20篇 |
2003年 | 22篇 |
2002年 | 15篇 |
2001年 | 5篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 14篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1927年 | 2篇 |
1923年 | 1篇 |
1913年 | 1篇 |
1909年 | 1篇 |
1899年 | 4篇 |
排序方式: 共有510条查询结果,搜索用时 31 毫秒
1.
2.
We derive a moderate deviation principle for the lower tail probabilities of the length of a longest increasing subsequence in a random permutation. It refers to the regime between the lower tail large deviation regime and the central limit regime. The present article together with the upper tail moderate deviation principle in Ref. 12 yields a complete picture for the whole moderate deviation regime. Other than in Ref. 12, we can directly apply estimates by Baik, Deift, and Johansson, who obtained a (non-standard) Central Limit Theorem for the same quantity. 相似文献
3.
Olaf Steinbach 《Numerische Mathematik》2002,90(4):775-786
Summary. In this paper we investigate a stability estimate needed in hybrid finite and boundary element methods, especially in hybrid
coupled domain decomposition methods including mortar finite elements. This stability estimate is equivalent to the stability
of a generalized projection in certain Sobolev spaces. Using piecewise linear trial spaces and appropriate piecewise constant test spaces,
the stability of the generalized projection is proved assuming some mesh conditions locally.
Received April 11, 2000 / Revised version received February 15, 2001 / Published online July 25, 2001 相似文献
4.
Mössbauer effect studies of Pt3−xFe1+x fcc ordered alloys in the range 4.2 K <T<300 K, in zero and in external magnetic field, for samples with x = 0.16 to 0.28, are reported. The low-temperature spectra show several satellite lines which are related to different excess-Fe nearest-neighbor configurations. Experiments in external fields give information on the different local spin structure at different concentrations. 相似文献
5.
6.
[reaction: see text] A new method to facilitate the separation of diastereomeric syn- and anti-1,3-diols is described. The method relies on the different hydrolysis rates of the corresponding diastereomeric acetonides. Treatment of a dichloromethane solution of syn- and anti-1,3-diol-acetonide with a catalytic amount of diluted aqueous hydrochloric acid leads to the selective cleavage of the anti diastereomer. The resulting anti-1,3-diol can be easily separated from the unchanged syn-1,3-diol-acetonide. 相似文献
7.
Fan Caiyun Jia Hongmei Deuther-Conrad Winnie Brust Peter Steinbach J?rg Liu Boli 《中国科学B辑(英文版)》2006,49(2):169-176
A novel 99mTc labeled complex, [N-[2-((2-oxo-2-(4-(3-phenylpropyl)piperazin-1-yl)ethyl) (2-mercaptoethyl)amino)acetyl]-2-aminoethanethiolato]Technetium(V)
oxide (PPPE-MAMA’-99mTcO) ([
99m
Tc]-2) has been designed and prepared based on the integrated approach. The corresponding rhenium complex (PPPE-MAMA’-ReO)(Re-2) has been prepared and characterized. In vitro competition binding assays show moderate affinity of Re-2 towards σ1 and σ2 receptors with K
i values of 8.67 ± 0.07 and 5.71 ± 1.88 μmol, respectively. Planar images obtained at 0.5 h, 4 h, 20 h after i.v. injection
indicate the accumulation of [
99m
Tc]-2 in MCF-7 human breast tumor bearing mice at 20 h. Furthermore, the accumulation of [
99m
Tc]-2 has been inhibited at 20 h after co-injection of [
99m
Tc]-2 plus haloperidol (1 mg/kg). Biodistribution studies of [
99m
Tc]-2 display an in vivo tumor uptake of 0.14% ± 0.01% ID/g at 24 h post i.v. injection with a tumor/muscle ratio of 6.02 ± 0.87. The above results
suggest that [
99m
Tc]-2, derived from a previously published lead compound, retains certain tumor uptake and affinity for σ receptors. [
99m
Tc]-2 may be used as a basis for further structural modifications to develop tumor imaging agents with high affinity for σ receptors. 相似文献
8.
Achim Hiller Jörg T. Patt Jörg Steinbach 《Journal of organometallic chemistry》2006,691(18):3737-3742
To evaluate the suitability of [18F]perchorylfluoride [18F]FClO3 as an electrophilic fluorination agent for the preparation of radiopharmaceuticals, the reactivity non-radioactive FClO3 towards 4-substituted trimethyltin aromatic compounds was studied. Contrary to the expectation, an electrophilic fluorination of the aromatic nucleus did not occur. The reaction of perchlorylfluoride with aromatic trimethylstannyl compounds resulted in the formation of trimethyltin fluoride and the respective destannylated aromatics in variable yields. 相似文献
9.
10.
A reversed-phase LC–MS method with quadrupole-time of flight (QTOF) detection has been developed for the determination of four dinitro-toluenesulfonic acids and two amino-nitro-toluenesulfonic acids in groundwater. The analytes were separated by HPLC with 0.1% (v/v) formic acid as mobile phase modifier compatible with mass spectrometric detection. QTOF-MS analysis with negative ion electrospray ionization afforded good selectivity and sensitivity for analysis of the dinitro- and amino-nitro-toluenesulfonic acids. Structure elucidation and confirmation were accomplished by tandem mass spectrometry. Characteristic ions resulting from the loss of NO, NO2, and SO2 from the [M–H]– ions were detected. An intense fragment ion at m/z 80 representing the [SO3]– ion was detected for all dinitro- and amino-nitro-toluenesulfonic acids. Solid-phase extraction using a co-polymer cartridge was developed for preconcentration of the analytes from water. Good recovery (>85%) was achieved when 0.1% formic acid was added into the water samples before extraction. Method detection limits ranged from 10 to 76 ng L–1 for the targeted compounds when 10 mL water was analyzed. Groundwater samples collected from wells close to a former ammunition plant in Stadtallendorf, Germany, were analyzed for the dinitro- and amino-nitro-toluenesulfonic acids. 相似文献