全文获取类型
收费全文 | 459篇 |
免费 | 24篇 |
国内免费 | 2篇 |
专业分类
化学 | 296篇 |
晶体学 | 4篇 |
力学 | 2篇 |
数学 | 9篇 |
物理学 | 174篇 |
出版年
2023年 | 7篇 |
2022年 | 3篇 |
2021年 | 14篇 |
2020年 | 9篇 |
2019年 | 17篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 13篇 |
2014年 | 25篇 |
2013年 | 27篇 |
2012年 | 38篇 |
2011年 | 38篇 |
2010年 | 27篇 |
2009年 | 14篇 |
2008年 | 39篇 |
2007年 | 41篇 |
2006年 | 30篇 |
2005年 | 25篇 |
2004年 | 20篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有485条查询结果,搜索用时 671 毫秒
1.
Maengseok Noh 《Journal of multivariate analysis》2007,98(5):896-915
The restricted maximum likelihood (REML) procedure is useful for inferences about variance components in mixed linear models. However, its extension to hierarchical generalized linear models (HGLMs) is often hampered by analytically intractable integrals. Numerical integration such as Gauss-Hermite quadrature (GHQ) is generally not recommended when the dimensionality of the integral is high. With binary data various extensions of the REML method have been suggested, but they have had unsatisfactory biases in estimation. In this paper we propose a statistically and computationally efficient REML procedure for the analysis of binary data, which is applicable over a wide class of models and design structures. We propose a bias-correction method for models such as binary matched pairs and discuss how the REML estimating equations for mixed linear models can be modified to implement more general models. 相似文献
2.
3.
4.
K. No Hyun J. Lee Ki M. Park Shim S. Lee Kwan H. Noh Sung K. Kim Ji Y. Lee Jong S. Kim 《Journal of heterocyclic chemistry》2004,41(2):211-219
A series of novel 1,3‐altemate calix[4]arene azacrowns having mono and bis crown ethers on the lower rim of the calix[4]arene framework were synthesized. Solid‐state structures confirmed the three dimensional conformation of compounds 1–3. 相似文献
5.
6.
7.
8.
Lee HJ Kim JH Jung HJ Kim KY Kim EJ Choi YS Yoon CJ 《Journal of computational chemistry》2004,25(2):169-178
The effect of thioamide substitution on the conformational stability of an azaglycine-containing peptide, For-AzaGly-NH2 (1), was investigated for the sake of finding possible applications by using ab initio and DFT methods. As model compounds, For-[psiCSNH]-AzaGly-NH2 (2), For-AzaGly-[psiCSNH]-NH2 (3), and For-[psiCSNH]-AzaGly-[psiCSNH]-NH2 (4) were used. Two-dimensional phi-psi potential energy surfaces (PESs) for 2-4 were calculated at the B3LYP/6-31G*//HF/6-31G* level in gas (epsilon = 1.0) and in water (epsilon = 78.4) by applying the isodensity polarizable continuum model (IPCM) method. On the basis of these PESs, the minimum energy conformations for 2-4 were characterized at the B3LYP level with 6-31G*, 6-311G**, and 6-31+G** basis sets. The remarkable structural effect of thioamide substitution for 2-4 is that beta-strand structure is observed as a global or local minimum. The minima of 2-4 are also compared with those for glycine and thioamide-containing glycine peptides. Our theoretical results demonstrate that compounds 2-4 would be used to design controllable secondary structures. 相似文献
9.
Yu-Ping Zhang Kwang-Pill Lee Hyun-Joo Noh Ali Md Showkat Seong-Ho Choi 《Microchemical Journal》2004,78(2):99-106
An appropriate optimization strategy should be used to find a desired resolution or selectivity with a minimum number of experiments in a limited time, which could assure the baseline separation of all target compounds. It was usually realized by means of a specialized computer program. In this paper, mapping optimization method and overlapping resolution mapping were compared for the optimization of a reversed-phase high-performance liquid chromatography (HPLC) isocratic separation of neutral compounds. The calculated resolutions and separation time of 7 to 10 experiments are fitted by different equations, which were used to build a contour plot with a minimum effective resolution and maximum retention time as a function of a mobile phase composition. The balance between resolution and analysis time could be easily realized by the overlapping of the final overlapping resolution mapping and analysis time mapping. The validity of the two methods was confirmed by some typical experiments. The models are simple, visual, and common without theoretical arithmetic. 相似文献
10.
Won Young Jung Byung Ho Noh Seung Hee Baek Gun-Dae Lee Seong Soo Park Seong-Soo Hong 《Reaction Kinetics and Catalysis Letters》2007,91(2):223-231
SBA-15 mesoporous material was prepared by microwave-hydrothermal method and was used as support in TiO2-loaded SBA-15 photocatalysts. The physical properties of these particles were investigated. We also examined the activity
of these samples as photocatalysts for the decomposition of orange II. Titania loaded on a silica matrix decreases the surface
area of the support as expected for TiO2 incorporation. For TiO2-loaded SBA-15 photocatalysts, the IR absorption at ∼960 cm−1 commonly accepted as the characteristic vibration of the Ti-O-Si bond. The photocatalytic activity increases with an increase
of the TiO2 loading. 相似文献