全文获取类型
收费全文 | 151篇 |
免费 | 1篇 |
专业分类
化学 | 67篇 |
力学 | 4篇 |
数学 | 49篇 |
物理学 | 32篇 |
出版年
2022年 | 2篇 |
2016年 | 2篇 |
2014年 | 1篇 |
2013年 | 7篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 8篇 |
2006年 | 2篇 |
2005年 | 11篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1967年 | 1篇 |
1966年 | 3篇 |
1963年 | 1篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有152条查询结果,搜索用时 0 毫秒
1.
The refined theory of the electroviscous lift forces is presented for the case when the separation distance between the particle and the wall is larger than the double-layer thickness. The theory is based on the lubrication approximation for motion of a long cylinder near a solid wall in creeping flow. The approximate analytical formula for the lift force valid for Pe=1 is derived and compared with the results of numerical calculations performed for an arbitrary Peclet number. The resulting electrokinetic lift force exceeds by several orders of magnitude one predicted by the previously developed theories of the lift force. The results for the electroviscous drag force indicate that when the double layer is thin compared with the particle size, the electroviscous drag is only a small correction (at most 10%) to the hydrodynamic drag force acting on a neutral particle moving near the wall. Copyright 2000 Academic Press. 相似文献
2.
Rapid high-performance liquid chromatographic (HPLC) procedures have been used to isolate and characterize thymosin beta 4 from different species. Crude extracts termed thymosin fraction 5A were prepared from porcine and ovine thymus glands as well as murine spleen. Each fraction 5A preparation was then fractionated by HPLC on a muBondapak C18 reversed-phase column. Porcine and ovine thymus fraction 5A, and murine spleen 5A, each yields a predominant peak at a retention time similar to that of bovine thymosin beta 4. Amino acid analysis as well as HPLC tryptic peptide mapping of these peaks indicate that they have homologous sequences to bovine thymosin beta 4. Chromatographic analysis of fresh murine thymus and spleen tissues also revealed protein peaks at the position of bovine beta 4, suggesting that thymosin beta 4 is the native protein present in the animal tissues. 相似文献
3.
A mild method for the synthesis of carbamates from amino alcohols involves sequential carboxylation with carbon dioxide, followed by a Mitsunobu reaction. Unexpectedly, the stereochemical course of the Mitsunobu reaction is dependent on whether the carbamic acid intermediate is N-substituted with hydrogen (retention) or carbon (inversion). 相似文献
4.
A procedure for the analysis of over 100 pesticides that only contain combinations of carbon, hydrogen, nitrogen, sulfur, and oxygen (i.e., no phosphorous or halogen atoms) has been developed. The procedure employs gas chromatography with a mass selective detector (GC/MSD), electron impact ionization, and selected ion monitoring. This GC/MSD procedure provided lower limits of quantitation and increased confirmational data compared to the traditional element-selective GC procedures that are commonly used for the detection of this "class" of pesticides. These analytical improvements were demonstrated by 26 pesticides that were detected at ng/g levels in a variety of fruit and vegetable matrixes using this procedure; these pesticides were missed by the traditional element-selective GC procedures. Validation of the procedure was performed using acetone extraction with solid-phase extraction cleanup. Twenty representative target pesticides were used to demonstrate repeatability and linearity of the chromatographic response and recovery from fruit and vegetable matrixes. 相似文献
5.
Recovery of226Ra in analysis is determined using225Ra separated by anion exchange from229Th and233U. Radium is coprecipitated with barium, and purified by ion exchange.226Ra and217At (decay product of225Ra) are measured by α-spectrometry.228Ra is determined both by β-counting228Ac and225Ac separated from228Ra and225Ra, and by α-counting its daughters after the decay of225Ra. Sources for α-spectrometry are prepared by electrodeposition (molecular plating). 相似文献
6.
Nissa C. Frank Dr. Darren J. Mercer Prof. Dr. Stephen J. Loeb 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(42):14076-14080
New dibenzo[24]crown‐8 ether derivatives were prepared that contain appendages with thioether donors that can coordinate to a metal ion. These macrocycles were then combined with 1,2‐bis(pyridinium) ethane axles to create two types of [2]rotaxane ligands; those with the four thioether donors on the crown ether and those with six donor groups, four from the crown ether and two more attached to the stoppering groups of the dumbbell. The crown ethers and both types of [2]rotaxane ligands were allowed to react with AgI ions to form metal‐organic rotaxane framework (MORF) style coordination polymers. The interlocked hexadentate ligand forms the first example of a new type of lattice containing interwoven frameworks resulting from both interpenetration of frameworks due to the presence of an interlocked ligand and more classical interpenetration of independent frameworks. 相似文献
7.
Dr. Michael Peter Mercer Sam Affleck Dr. Edgardo Maximiliano Gavilán-Arriazu Dr. Alana Aragón Zülke Dr. Philip A. Maughan Shivam Trivedi Prof. Maximilian Fichtner Dr. Anji Reddy Munnangi Prof. Ezequiel P. M. Leiva Prof. Harry Ernst Hoster 《Chemphyschem》2022,23(5):e202100748
Sodium-ion batteries (NIBs) utilize cheaper materials than lithium-ion batteries (LIBs) and can thus be used in larger scale applications. The preferred anode material is hard carbon, because sodium cannot be inserted into graphite. We apply experimental entropy profiling (EP), where the cell temperature is changed under open circuit conditions. EP has been used to characterize LIBs; here, we demonstrate the first application of EP to any NIB material. The voltage versus sodiation fraction curves (voltage profiles) of hard carbon lack clear features, consisting only of a slope and a plateau, making it difficult to clarify the structural features of hard carbon that could optimize cell performance. We find additional features through EP that are masked in the voltage profiles. We fit lattice gas models of hard carbon sodiation to experimental EP and system enthalpy, obtaining: 1. a theoretical maximum capacity, 2. interlayer versus pore filled sodium with state of charge. 相似文献
8.
T. H. Prettyman C. S. Cooper P. N. Luke P. A. Russo M. Amman D. J. Mercer 《Journal of Radioanalytical and Nuclear Chemistry》1998,233(1-2):257-264
A physics-based approach to gamma-ray response-function generation is presented in which the response of CdZnTe detectors
is modeled from first principles. Numerical modeling is used to generate response functions needed for spectrum analysis for
general detector configurations (e.g., electrode design, detector materials and geometry, and operating conditions). With
numerical modeling, requirements for calibration and characterization are significantly reduced. Elements of the physics-based
model, including gamma-ray transport, charge carrier drift and diffusion, and circuit response, are presented. Calculated
and experimental gamma-ray spectra are compared for a coplanar-grid CdZnTe detector. 相似文献
9.
Peter R. Mercer 《Journal of Mathematical Analysis and Applications》2008,344(2):921-926
We obtain Midpoint and Trapezoid Rules for the Riemann-Stieltjes integral which engender a natural generalization of Hadamard's integral inequality. Error terms are then obtained for this Riemann-Stieltjes Trapezoid Rule and other related quadrature rules. 相似文献
10.
We analytically model the transport of dirt in the industrial washing of wool using the advection–diffusion equation in two dimensions. Separation of variables leads to a Sturm–Liouville problem where the analytic solution reveals how contamination is distributed both along and down the wool and indicates the operating parameter regimes that optimise the cleaning efficiency. 相似文献