全文获取类型
收费全文 | 182篇 |
免费 | 7篇 |
专业分类
化学 | 138篇 |
晶体学 | 1篇 |
数学 | 11篇 |
物理学 | 39篇 |
出版年
2022年 | 2篇 |
2019年 | 2篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 10篇 |
2011年 | 13篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 11篇 |
2006年 | 12篇 |
2005年 | 14篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 10篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有189条查询结果,搜索用时 31 毫秒
81.
82.
83.
The tetraenic lactone 1 affords the two configurationally possible mono-Diels-Alder adducts. Each of these afforded a bis-adduct. The configurations of all of these adducts have been established. 相似文献
84.
85.
Fabian S. Menges Stephanie M. Craig Niklas Ttsch Aaron Bloomfield Subrata Ghosh Hans‐Jrg Krüger Mark A. Johnson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(4):1304-1307
We describe a systematic method for the preparation and spectroscopic characterization of a CO2 molecule coordinated to an activated bisphenoidal nickel(I) compound containing a tetraazamacrocyclic ligand in the gas phase. The resulting complex was then structurally characterized by using mass‐selected vibrational predissociation spectroscopy. The results indicate that a highly distorted CO2 molecule is bound to the metal center in an η2‐C,O coordination mode, thus establishing an efficient and rational method for the preparation of metal‐activated CO2 for further studies using ion chemistry techniques. 相似文献
86.
Brubaker CE Messersmith PB 《Langmuir : the ACS journal of surfaces and colloids》2012,28(4):2200-2205
The natural world provides many examples of robust, permanent adhesive platforms. Synthetic adhesive interfaces and materials inspired by mussels of genus Mytulis have been extensively applied, and it is expected that characterization and adaptation of several other biological adhesive strategies will follow the Mytilus edulis model. These candidate species will be introduced, along with a discussion of the adhesive behaviors that make them attractive for synthetic adaptation. While significant progress has been made in the development of biologically inspired adhesive interfaces and materials, persistent questions, current challenges, and emergent areas of research will be also be discussed. 相似文献
87.
Grey JK Kim DY Donley CL Miller WL Kim JS Silva C Friend RH Barbara PF 《The journal of physical chemistry. B》2006,110(38):18898-18903
Fluorescence emission spectra were recorded for isolated polymer chains of the polyfluorene copolymer, F8BT [poly(9,9-di-n-octylfluorene-alt-benzothiadiazole)], at 298 and 20 K for two molecular weights (chain lengths). For long-chain F8BT at 298 K, the observed distribution of single-molecule emission maxima G(Emax) is bimodal, with peaks at approximately 2.35 eV ("blue") and approximately 2.25 eV ("red"). Previously, the red forms have been assigned to polymer chains that possess intrachain contacts, which lowers the local singlet exciton energy. At approximately 20 K, G(Emax) collapses into a single broad distribution centered at approximately 2.3 eV for long-chain F8BT. However, this distribution can be further divided into a high-energy edge that is dominated by the "blue" form, while the remainder of the distribution is composed of the "red" form. Low-molecular-weight F8BT samples emit exclusively from the blue form, and no shift in peak maxima with low temperature was observed. A Franck-Condon analysis reveals a decrease in emitting state displacements between spectra measured at 298 and 20 K, suggesting that temperature-induced structural displacements are responsible for the change in the bimodal emission. 相似文献
88.
John G. Bruno Maria P. Carrillo Taylor Phillips Carrie J. Andrews 《Journal of fluorescence》2010,20(6):1211-1223
A novel high-throughput screening method is described in which a family of DNA aptamers selected against E. coli outer membrane proteins (OMPs) is subjected to PCR in the presence of fluorophore-dUTP conjugates using Deep Vent® exo- polymerase. The fluorophore-doped aptamers and their complementary strands are then heated to render them single-stranded and screened in filter well microtiter plates for fluorescence resonance energy transfer (FRET) assay potential. Using this system, a superior competitive FRET-aptamer designated EcO 4R was identified and the location of its putative binding pocket was determined by individually testing FRET potential in each of the secondary loop structures. By labeling the binding pocket with Alexa Fluor (AF) 647 and binding the aptamer to heavily Black Hole Quencher-3 (BHQ-3)-labeled E. coli bacteria, detection of as few as 30 live unlabeled E. coli per ml was achieved in a competitive displacement FRET assay format. The far red fluorescence emission enables detection in largely blue-green autofluorescent matrices. In addition, the competitive transfer of AF 647-EcO-4R aptamer to unlabeled E. coli cells after a 15 min equilibration period was verified by fluorescence microscopy. The present study also demonstrated that high aptamer affinity is not well correlated with competitive FRET potential. 相似文献
89.
Anthony S. Stender Lindsay A. Giem Matt C. Bunte Carrie L. Burns Lindsay D. Odom Diane S. Fitzpatrick Christopher J. Biorn Eugene T. Smith 《The Chemical Educator》2000,5(6):321-323
A laboratory exercise, the analysis of arsenic in drinking water by graphite furnace atomic absorption spectroscopy (GFAA), is presented for use in an undergraduate instrumental methods course. The purpose of this GFAA exercise is to expose students to a practical and commonly used application, to provide students with hands-on experience with the instrument, and to reinforce concepts taught in the classroom. Students safely analyze a real-world sample containing an analyte in the parts-per-billion concentration range. 相似文献
90.
Brandon J. O'Neill David H. K. Jackson Dr. Anthony J. Crisci Carrie A. Farberow Fengyuan Shi Dr. Ana C. Alba‐Rubio Dr. Junling Lu Dr. Paul J. Dietrich Dr. Xiangkui Gu Dr. Christopher L. Marshall Prof. Peter C. Stair Dr. Jeffrey W. Elam Dr. Jeffrey T. Miller Prof. Fabio H. Ribeiro Prof. Paul M. Voyles Prof. Jeffrey Greeley Prof. Manos Mavrikakis Prof. Susannah L. Scott Prof. Thomas F. Kuech Prof. James A. Dumesic 《Angewandte Chemie (International ed. in English)》2013,52(51):13808-13812
Atomic layer deposition (ALD) of an alumina overcoat can stabilize a base metal catalyst (e.g., copper) for liquid‐phase catalytic reactions (e.g., hydrogenation of biomass‐derived furfural in alcoholic solvents or water), thereby eliminating the deactivation of conventional catalysts by sintering and leaching. This method of catalyst stabilization alleviates the need to employ precious metals (e.g., platinum) in liquid‐phase catalytic processing. The alumina overcoat initially covers the catalyst surface completely. By using solid state NMR spectroscopy, X‐ray diffraction, and electron microscopy, it was shown that high temperature treatment opens porosity in the overcoat by forming crystallites of γ‐Al2O3. Infrared spectroscopic measurements and scanning tunneling microscopy studies of trimethylaluminum ALD on copper show that the remarkable stability imparted to the nanoparticles arises from selective armoring of under‐coordinated copper atoms on the nanoparticle surface. 相似文献