全文获取类型
收费全文 | 97篇 |
免费 | 5篇 |
国内免费 | 6篇 |
专业分类
化学 | 38篇 |
力学 | 4篇 |
数学 | 53篇 |
物理学 | 13篇 |
出版年
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 11篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2006年 | 5篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1996年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有108条查询结果,搜索用时 625 毫秒
1.
Nguyen Minh Chuong Bui Kien Cuong 《Proceedings of the American Mathematical Society》2004,132(12):3589-3597
A class of Cauchy problems for interesting complicated periodic pseudodifferential equations is considered. By the Galerkin-wavelet method and with weak solutions one can find sufficient conditions to establish convergence estimates of weak Galerkin-wavelet solutions to a Cauchy problem for this class of equations.
2.
The pigments Luteoskyrin (Ls) and Rugulosin (Rg) might adopt a priori two extreme conformations, a planar and an angular one. To determine the predominant conformation in solution, the nature of the lowest energy transition of the chromophores and the presence of intramolecular H-bonding have been investigated. The solvent effects on electronic absorption and CD spectra indicated the π-π* nature of the lowest energy transition. Treatments of the electronic absorption results according to McRae and Kosower relations, IR absorption and PMR spectra suggested the presence of strong intra-molecular H-bonds. From these results it was concluded that Ls and Rg adopted in a variety of solvents the most planar conformation. 相似文献
3.
The purpose of this paper is to study the boundedness of the wavelet integral operator on the Besov, BMO, and H 1 spaces. Furthermore, for the basic wavelet with compact support, the boundedness of the wavelet transform on the weighted Besov spaces and on the weighted BMO spaces associated with a tempered weight function is also established. 相似文献
4.
This paper deals with a nonsmooth semi-infinite multiobjective/vector optimization problem (SIMOP, for short). We first establish necessary and sufficient conditions for (local) strongly isolated solutions and (local) positively properly efficient solutions of an SIMOP. Then, we propose a dual problem to the SIMOP under consideration and examine weak and strong duality relations between them. 相似文献
5.
Howard Yi Fan Sim Jaslyn Ru Ting Chen Charlynn Sher Lin Koh Dr. Hiang Kwee Lee Dr. Xuemei Han Gia Chuong Phan-Quang Jing Yi Pang Dr. Chee Leng Lay Dr. Srikanth Pedireddy Dr. In Yee Phang Prof. Edwin Kok Lee Yeow Prof. Xing Yi Ling 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17145-17151
The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d-band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of >44 % with high ammonia yield rate of >161 μg mgcat−1 h−1 under ambient conditions. The strategy lowers electrocatalyst d-band position to weaken H adsorption and concurrently creates electron-deficient sites to kinetically drive NRR by promoting catalyst–N2 interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by >44-fold compared to without ZIF (ca. 1 %). The Pt/Au-NZIF interaction is key to enable strong N2 adsorption over H atom. 相似文献
6.
制备了β-环糊精(β-CD)-三氟氯氰菊酯(CHL)包合物,采用差示扫描量热分析法和核磁共振波谱法对包合物进行表征.实验采用1HNMR研究包合物的空间结构,推测出三氟氯氰菊酯同β-CD的包合方式是从大口端进入β-CD.用化学软件对β-CD与CHL包合方式计算发现,CHL从β-CD的大口端和小口端进入,总能量分别为108.1kJ/mol与129.2kJ/mol,表明CHL从β-CD的大口端进入形成的包合物能量最低,结构最稳定.在25℃下,实验测得β-CD-三氟氯氰菊酯包合物形成常数为340.6L?mol-1,包合比是1∶1.热动力学方法研究了温度变化对包合反应的影响,计算得出包合过程的焓变-50.29kJ?mol-1、熵变120.6J?K-1?mol-1及自由能变化-14.45kJ?mol-1,进而确定了包合反应的主要驱动力是焓. 相似文献
7.
PAMAM树状大分子对酮基布洛芬溶解度的影响 总被引:1,自引:1,他引:1
以酮洛芬为模型药物,研究聚酰胺-胺(PAMAM)树状大分子对酮洛芬的增溶作用,并探讨其作用机理.采用紫外光谱法测定了G1.0、G1.5、G2.0、G2.5、G3.0、G3.5PAMAM在不同浓度和不同pH时对酮洛芬的增溶量.并运用计算机模拟方法对PAMAM与酮洛芬相互作用的机理进行了探讨.实验结果表明,酮洛芬的溶解度随溶液pH值变化而变化,在pH4.0~6.0范围内,PAMAM树状大分子对酮洛芬的增溶量随着PAMAM的代数、浓度和溶液pH的增加而增大.整代和半代都具有增溶作用.然而,在同一pH条件下,对于具有相同官能团数目的整代和半代,整代增溶效果要高于半代.计算机模拟结果表明PAMAM与酮洛芬主要靠静电作用力结合.增溶机理可能是酮洛芬的羧基与PAMAM的伯胺和叔胺发生静电作用. 相似文献
8.
9.
We present an exact formula for the radius of robust feasibility of uncertain linear programs with a compact and convex uncertainty set. The radius of robust feasibility provides a value for the maximal ‘size’ of an uncertainty set under which robust feasibility of the uncertain linear program can be guaranteed. By considering spectrahedral uncertainty sets, we obtain numerically tractable radius formulas for commonly used uncertainty sets of robust optimization, such as ellipsoids, balls, polytopes and boxes. In these cases, we show that the radius of robust feasibility can be found by solving a linearly constrained convex quadratic program or a minimax linear program. The results are illustrated by calculating the radius of robust feasibility of uncertain linear programs for several different uncertainty sets. 相似文献
10.
Clarke coderivatives of efficient point multifunctions in parametric vector optimization 总被引:1,自引:0,他引:1
Thai Doan Chuong 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(1):273-285
The paper is devoted to the study of the Clarke/circatangent coderivatives of the efficient point multifunction of parametric vector optimization problems in Banach spaces. We provide inner/outer estimates for evaluating the Clarke/circatangent coderivative of this multifunction in a broad class of conventional vector optimization problems in the presence of geometrical, operator and (finite and infinite) functional constraints. Examples are given for analyzing and illustrating the obtained results. 相似文献