全文获取类型
收费全文 | 221篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
化学 | 148篇 |
力学 | 3篇 |
数学 | 28篇 |
物理学 | 61篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 10篇 |
2015年 | 9篇 |
2014年 | 8篇 |
2013年 | 10篇 |
2012年 | 24篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 3篇 |
2008年 | 13篇 |
2007年 | 14篇 |
2006年 | 14篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有240条查询结果,搜索用时 0 毫秒
231.
232.
Linda M. Benson Christopher J. Mason Oren Friedman Hirohito Kita Harold Robert Bergen III Douglas A. Plager 《Journal of separation science》2009,32(1):44-56
Allergic rhinitis (AR), chronic rhinosinusitis (CRS), and asthma are prevalent airway diseases that can have a substantial impact on a patient's quality of life. MS analyses of biological fluids can effectively screen for proteins associated with disease processes, however, initial detection of diagnostic proteins is difficult due to protein complexity and dynamic range. To enhance the detection of lower abundance proteins, intact nasal lavage fluid (NLF) proteins from nonpolypoid AR and from asthmatic CRS patients were extensively fractionated prior to LC/MS/MS analysis. Pooled NLF samples were processed to remove low molecular weight molecules and high abundance plasma proteins. Anion exchange (AX) chromatography followed by RP‐LC further separated the remaining intact NLF proteins. The resulting fractions were digested with trypsin and the peptides analyzed by LC/MS/MS. Spectra were searched with MASCOT, SEQUEST, and X!Tandem to obtain peptide identifications and subsequently analyzed by Scaffold software to identify parent proteins with at least 99% confidence. The 197 identified proteins are compared to those previously cited in the literature and the workflow evaluated to determine the usefulness for the detection of lower abundance proteins. This is the first extensive list of NLF proteins generated from CRS patients with coexisting asthma. 相似文献
233.
Toward a versatile toolbox for cucurbit[n]uril-based supramolecular hydrogel networks through in situ polymerization 下载免费PDF全文
Ji Liu Cindy Soo Yun Tan Yang Lan Oren A. Scherman 《Journal of polymer science. Part A, Polymer chemistry》2017,55(18):3105-3109
The success of exploiting cucurbit[n]uril (CB[n])-based molecular recognition in self-assembled systems has sparked a tremendous interest in polymer and materials chemistry. In this study, polymerization in the presence of host-guest complexes is applied as a modular synthetic approach toward a diverse set of CB[8]-based supramolecular hydrogels with desirable properties, such as mechanical strength, toughness, energy dissipation, self-healing, and shear-thinning. A range of vinyl monomers, including acrylamide-, acrylate-, and imidazolium-based hydrophilic monomers, could be easily incorporated as the polymer backbones, leading to a library of CB[8] hydrogel networks. This versatile strategy explores new horizons for the construction of supramolecular hydrogel networks and materials with emergent properties in wearable and self-healable electronic devices, sensors, and structural biomaterials. © 2017 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3105–3109 相似文献
234.
Zehuan Huang Liulin Yang Yiliu Liu Prof. Zhiqiang Wang Dr. Oren A. Scherman Prof. Xi Zhang 《Angewandte Chemie (International ed. in English)》2014,53(21):5351-5355
A new method in which supramolecular polymerization is promoted and controlled through self‐sorting is reported. The bifunctional monomer containing p‐phenylene and naphthalene moieties was prepared. Supramolecular polymerization is promoted by selective recognition between the p‐phenylene group and cucurbit[7]uril (CB[7]), and 2:1 complexation of the naphthalene groups with cucurbit[8]uril (CB[8]). The process can be controlled by tuning the CB[7] content. This development will enrich the field of supramolecular polymers with important advances towards the realization of molecular‐weight and structural control. 相似文献
235.
A conformational search procedure (HUNTER), in combination with the MM3(92) program, was used for the exploration of the conformational hypersurface of alkyl-substituted cyclohexanes and for the calculation of their chair/twist-boat (TB) energy gap. The systems studied were conformationally unconstrained polyalkylcyclohexanes (alkyl = methyl, ethyl, isopropyl, and tert-butyl) possessing either geminal and/or vicinal arrangements of the alkyl groups, but differing in the number of alkyl substituents and in their relative disposition (i.e., cis or trans). The calculations indicate that in 1,1,3,3,5,5-hexaisopropylcyclohexane the TB is the lowest energy form. Modification of the cis,trans relationship of vicinal alkyl groups changes the chair/TB energy gap, and in the minimum energy conformation of cis,trans,trans-1,2,3,4-tetraisopropylcyclohexane (23c) and cis,syn,cis-1,2,4,5-tetraisopropylcyclohexane (31c) the cyclohexyl ring adopts a TB conformation. The tetrasubstituted systems cis,syn,cis-1,2-diisopropyl-3,4-dimethylcyclohexane (46), cis,syn,cis-1,4-diisopropyl-2,5-dimethyl-cyclohexane (47), and cis,trans,trans-1,2-diisopropyl-3,4-dimethylcyclohexane (41) are the least crowded monocyclic unconstrained cyclohexanes found in which the TB conformation is of lower energy than the chair form. The present study indicates that two methyls and two isopropyl substituents are sufficient for stabilizing the TB form of a cyclohexyl ring relative to the chair form. 相似文献
236.
Constantin D. Sahm Eric Mates-Torres Nora Eliasson Kamil Sokoowski Andreas Wagner Kristian E. Dalle Zehuan Huang Oren A. Scherman Leif Hammarstrm Max García-Melchor Erwin Reisner 《Chemical science》2021,12(26):9078
Colloidal photocatalysts can utilize solar light for the conversion of CO2 to carbon-based fuels, but controlling the product selectivity for CO2 reduction remains challenging, in particular in aqueous solution. Here, we present an organic surface modification strategy to tune the product selectivity of colloidal ZnSe quantum dots (QDs) towards photocatalytic CO2 reduction even in the absence of transition metal co-catalysts. Besides H2, imidazolium-modified ZnSe QDs evolve up to 2.4 mmolCO gZnSe−1 (TONQD > 370) after 10 h of visible light irradiation (AM 1.5G, λ > 400 nm) in aqueous ascorbate solution with a CO-selectivity of up to 20%. This represents a four-fold increase in CO-formation yield and 13-fold increase in CO-selectivity compared to non-functionalized ZnSe QDs. The binding of the thiolated imidazolium ligand to the QD surface is characterized quantitatively using 1H-NMR spectroscopy and isothermal titration calorimetry, revealing that a subset of 12 to 17 ligands interacts strongly with the QDs. Transient absorption spectroscopy reveals an influence of the ligand on the intrinsic charge carrier dynamics through passivating Zn surface sites. Density functional theory calculations indicate that the imidazolium capping ligand plays a key role in stabilizing the surface-bound *CO2− intermediate, increasing the yield and selectivity toward CO production. Overall, this work unveils a powerful tool of using organic capping ligands to modify the chemical environment on colloids, thus enabling control over the product selectivity within photocatalyzed CO2 reduction.A photocatalyst system consisting of ZnSe quantum dots modified with a thiolated imidazolium capping ligand for visible light-driven reduction of aqueous CO2 to CO is reported without the need for a metal complex co-catalyst. 相似文献
237.
Tseng C. L. Li C. A. Oren S. S. 《Journal of Optimization Theory and Applications》2000,105(3):707-730
In this paper, we present a unified decommitment method to solve the unit commitment problem. This method starts with a solution having all available units online at all hours in the planning horizon and determines an optimal strategy for decommitting units one at a time. We show that the proposed method may be viewed as an approximate implementation of the Lagrangian relaxation approach and that the number of iterations is bounded by the number of units. Numerical tests suggest that the proposed method is a reliable, efficient, and robust approach for solving the unit commitment problem. 相似文献
238.
239.
S. S. Oren 《Journal of Optimization Theory and Applications》1982,37(2):137-147
Recent attempts to assess the performance of SSVM algorithms for unconstrained minimization problems differ in their evaluations from earlier assessments. Nevertheless, the new experiments confirm earlier observations that, on certain types of problems, the SSVM algorithms are far superior to other variable metric methods. This paper presents a critical review of these recent assessments and discusses some current interpretations advanced to explain the behavior of SSVM methods. The paper examines the new empirical results, in light of the original self-scaling theory, and introduces a new interpretation of these methods based on anL-function model of the objective function. This interpretation sheds new light on the performance characteristics of the SSVM methods, which contributes to the understanding of their behavior and helps in characterizing classes of problems which can benefit from the self-scaling approach.The subject of this paper was presented at the ORSA/TIMS National Meeting in New York, 1978.This work was done while the author was with the Analysis Research Group, Xerox Palo Alto Research Center, Palo Alto, California. 相似文献
240.
Oren Tirosh Yehoshua Katzhendler Yechezkel Barenholz Isaac Ginsburg Ron Kohen 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract This work describes the synthesis and characterization of a new family of antioxidants. The molecules have the same active group, but different oil-to-water and octanol-to-water partition coefficients due to different substituents. Three new molecules were synthesized based on the chemical structure of the primary amide attached to a thiophosphate group forming an amidothionophosphate. The amidothionophosphate molecules were exposed to the oxidative stress of hydrogen peroxide and sodium hypochlorite, and the chemical changes following the exposure were monitored by 31P NMR. The reaction constants with reactive oxygen species such as hydroxyl radical and superoxide radical were also calculated and found to be 1.5?109 M-1 and 8.1?102 M-1S-1, respectively. In order to elucidate the ability of amidothionophosphates to act as antioxidants in protecting lipids and proteins, we examined damage prevention in Bovine serum albumin, egg phosphatidyl choline liposomes and lipid emulsions following oxidative smss. Amidothionophosphate showed unique protection properties in these models. In contrast to other antioxidant molecules (ascorbic acid, cystine, and a-tocopherol) the new group did not have any pro-oxidative effects as measured by oxygen consumption from buffer solutions containing amidothionophosphates and cupric sulfate as a redox-active metal. Amidothionophosphates reduced significantly and in a dose-dependent manner the oxidative burst in human neutrophils as measured by luminol-dependent chemiluminescence, and they also markedly depressed the killing of human fibroblasts by mixtures of glucose oxidase and streptolysin S. The toxicity of these molecules was tested by i.p. injection of up to 1000 mg/kg to white Sabra mice. No mortality was observed 30 days after administration of up to 500 mg/kg. 相似文献