全文获取类型
收费全文 | 235篇 |
免费 | 4篇 |
专业分类
化学 | 134篇 |
晶体学 | 1篇 |
数学 | 3篇 |
物理学 | 101篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 13篇 |
2012年 | 10篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 15篇 |
2003年 | 9篇 |
2002年 | 14篇 |
2001年 | 14篇 |
2000年 | 13篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 10篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1938年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有239条查询结果,搜索用时 31 毫秒
131.
We have performed a large‐scale evaluation of current computational methods, including conventional small‐molecule force fields; semiempirical, density functional, ab initio electronic structure methods; and current machine learning (ML) techniques to evaluate relative single‐point energies. Using up to 10 local minima geometries across ~700 molecules, each optimized by B3LYP‐D3BJ with single‐point DLPNO‐CCSD(T) triple‐zeta energies, we consider over 6500 single points to compare the correlation between different methods for both relative energies and ordered rankings of minima. We find that the current ML methods have potential and recommend methods at each tier of the accuracy‐time tradeoff, particularly the recent GFN2 semiempirical method, the B97‐3c density functional approximation, and RI‐MP2 for accurate conformer energies. The ANI family of ML methods shows promise, particularly the ANI‐1ccx variant trained in part on coupled‐cluster energies. Multiple methods suggest continued improvements should be expected in both performance and accuracy. 相似文献
132.
Dr. Atef Shalabney Dr. Jino George Dr. Hidefumi Hiura Dr. James A. Hutchison Dr. Cyriaque Genet Prof. Petra Hellwig Prof. Thomas W. Ebbesen 《Angewandte Chemie (International ed. in English)》2015,54(27):7971-7975
Ground‐state molecular vibrations can be hybridized through strong coupling with the vacuum field of a cavity optical mode in the infrared region, leading to the formation of two new coherent vibro‐polariton states. The spontaneous Raman scattering from such hybridized light–matter states was studied, showing that the collective Rabi splitting occurs at the level of a single selected bond. Moreover, the coherent nature of the vibro‐polariton states boosts the Raman scattering cross‐section by two to three orders of magnitude, revealing a new enhancement mechanism as a result of vibrational strong coupling. This observation has fundamental consequences for the understanding of light‐molecule strong coupling and for molecular science. 相似文献
133.
Parks JJ Champagne AR Hutchison GR Flores-Torres S Abruña HD Ralph DC 《Physical review letters》2007,99(2):026601
We study electron transport through C(60) molecules in the Kondo regime using a mechanically controllable break junction. By varying the electrode spacing, we are able to change both the width and the height of the Kondo resonance, indicating modification of the Kondo temperature and the relative strength of coupling to the two electrodes. The linear conductance as a function of T/T(K) agrees with the scaling function expected for the spin-1/2 Kondo problem. We are also able to tune finite-bias Kondo features which appear at the energy of the first C(60) intracage vibrational mode. 相似文献
134.
Jespersen ML Inman CE Kearns GJ Foster EW Hutchison JE 《Journal of the American Chemical Society》2007,129(10):2803-2807
A new method for assembling organic monolayers on gold is reported that employs hafnium ions as linkers between a phosphonate headgroup and the gold surface. Monolayers of octadecylphosphonic acid (ODPA) formed on gold substrates that had been pretreated with hafnium oxychloride are representative of this new class of organic thin films. The monolayers are dense enough to completely block assembly of alkanethiols and resist displacement by alkanethiols. The composition and structure of the monolayers were investigated by contact angle goniometry, XPS, PM-IRRAS, and TOF-SIMS. From these studies, it was determined that this assembly strategy leads to the formation of ODPA monolayers similar in quality to those typically formed on metal oxide substrates. The assembly method allows for the ready generation of patterned surfaces that can be easily prepared by first patterning hafnium on the gold surface followed by alkanephosphonate assembly. Using the bifunctional (thiol-phosphonate) 2-mercaptoethylphosphonic acid (2-MEPA), we show that this new assembly chemistry is compatible with gold-thiol chemistry and use TOF-SIMS to show that the molecule attaches through the phosphonate functionality in the patterned region and through the thiol in the bare gold regions. These results demonstrate the possibility of functionalizing metal substrates with monolayers typically formed on metal oxide surfaces and show that hafnium-gold chemistry is complementary and orthogonal to well-established gold-thiol assembly strategies. 相似文献
135.
Crystallites of Nb4W13O47 were heated by a focussed electron beam in an oxygen atmosphere (pO2 = 20 mbar) inside the gas reaction cell installed within the polepiece of a 400 kilovolt transmission electron microscope. The HRTEM investigation of the resulting oxidation products revealed the presence of structures which differ significantly from those generated by conventional oxidation in air. In a first reaction step, the arrangement of filled pentagonal tunnels in the tetragonal tungsten bronze (TTB) substructure became disordered, and small segregations of ReO3‐type structure arose. Further treatment largely destroyed the original TTB‐type structure. In the residual bronze‐type structure, only a few TTB subcells were preserved while unusual structural arrangements, including hexagonal and heptagonal tunnels, were formed. Moreover, microdomains of a new intergrowth structure between the TTB type and the ReO3 type occur. This structure comprises double pentagons of octahedra as well as slabs of diamond‐linked pentagonal columns. The oxygen excess in the oxidation product is structurally accommodated in large ReO3‐type domains of tungsten oxide. 相似文献
136.
Hutchison W.D. Harker S.J. Chaplin D.H. Funk T. Klein E. 《Hyperfine Interactions》1999,120(1-8):193-198
Combined host (∼95 at% enriched stable 57Fe) and very dilute impurity (∼0.01 at% radioactive 60Co) NMR signals have been obtained on the one sample of polycrystalline Fe foil utilising perturbations to the gamma anisotropy
from in situ thermally oriented 60Co nuclei for both resonances. The NMR-TDNO signals on the 57Fe sites have been followed down to applied magnetic fields well below the host magnetic saturation and exhibited two distinct
components; a strong, narrow homogeneous signal, superimposed over a broader inhomogeneous signal. The impurity 60Co57Fe inhomogeneous resonance has been studied with three pulse NMRON and the irreversible decay of the nuclear spin echo measured
as a function of applied magnetic field.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
137.
Nishimura K. Mori K. Ohya S. Muto S. Hutchison W.D. Harker S.J. Chaplin D.H. 《Hyperfine Interactions》1999,120(1-8):203-207
Low-temperature nuclear orientation was applied to study hyperfine interactions of 142Pr, 147Nd and 143,144Pm nuclei in Pr0.5Nd0.5Ni single crystal. Angular distributions, temperature dependence and external magnetic field effects on the γ-ray anisotropy
are presented. A Nd-Pm exchange interaction seems to dominate the magnetic properties of Pm ions in this system.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
138.
The accumulation of iron and arsenic from aqueous solution by lettuce leaves biomass was investigated using Mössbauer and EXAFS spectroscopic techniques. Mössbauer spectroscopy results show that iron is oxidized during sorption while EXAFS results indicate that iron is coordinated by approximately 6 oxygen and 2 carbon atoms while arsenic is coordinated by approximately 4 oxygen atoms with iron as a second neighbor. 相似文献
139.
Flores-Torres S Hutchison GR Soltzberg LJ Abruña HD 《Journal of the American Chemical Society》2006,128(5):1513-1522
We have prepared and characterized a series of multimetallic oligomers of Ru using the pi-conjugated bridging ligand tetra-2-pyridyl-1,4-pyrazine (tppz), as well as mixed-ligand complexes with terpyridine end caps, and analyzed their electrochemical and spectroscopic properties, comparing them with modern computational electronic structure methods. The results suggest that the high degree of metal-metal interunit communication in these linear oligomers yields low HOMO-LUMO gaps, high delocalization, and the onset of "quasi-band" features, all indicative that these compounds should be excellent molecular wire materials. Recent spectroscopic and excited-state analyses of these and related compounds focus on optically accessible states, which ignore optically silent frontier electronic states more relevant to nanoelectronic applications. 相似文献
140.
Parks BW Gilbertson RD Hutchison JE Healey ER Weakley TJ Rapko BM Hay BP Sinkov SI Broker GA Rogers RD 《Inorganic chemistry》2006,45(4):1498-1507
This report describes an investigation into the coordination chemistry of trivalent lanthanides in solution and the solid state with acyclic and preorganized bicyclic malonamide ligands. Two experimental investigations were performed: solution binding affinities were determined through single-phase spectrophotometric titrations and the extent of conformational change upon binding was investigated with single-crystal X-ray crystallography. Both experimental methods compare the bicyclic malonamide (BMA), which is designed to be preorganized for binding trivalent lanthanides, to an analogous acyclic malonamide. Results from the spectrophotometric titrations indicate that BMA exhibits a 10-100x increase in binding affinity to Ln(III) over acyclic malonamide. In addition, BMA forms compounds with high ligand-metal ratios, even when competing with water and nitrate ligands for binding sites. The crystal structures exhibit no significant differences in the nature of the binding between Ln(III) and the BMA or acyclic malonamide. These results support the conclusion that rational ligand design can lead to compounds that enhance the binding affinities within a ligand class. 相似文献