全文获取类型
收费全文 | 166篇 |
免费 | 10篇 |
专业分类
化学 | 122篇 |
力学 | 3篇 |
数学 | 10篇 |
物理学 | 41篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有176条查询结果,搜索用时 31 毫秒
111.
The symmetric marching technique developed in [1,2] has been extended to the elliptic equations with variable coefficients involving mixed partial derivatives. The restricted class of such equations of the form uxx+2B(x, y)uxy+c(x,y)uyy=0 have been considered. Numerical results of model problems solved are presented. 相似文献
112.
Adams J Adler C Aggarwal MM Ahammed Z Amonett J Anderson BD Arkhipkin D Averichev GS Bai Y Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bezverkhny BI Bharadwaj S Bhatia VS Bichsel H Bland LC Blyth CO Bonner BE Botje M Boucham A Brandin A Bravar A Cadman RV Cai XZ Caines H Calderón de la Barca Sánchez M Carroll J Castillo J Cebra D Chaloupka P Chattopdhyay S Chen HF Chen Y Cheng J Cherney M Chikanian A Christie W Coffin JP Cormier TM Cramer JG Crawford HJ 《Physical review letters》2004,92(18):182301
The transverse mass spectra and midrapidity yields for Xis and Omegas are presented. For the 10% most central collisions, the (-)Xi(+)/h(-) ratio increases from the Super Proton Synchrotron to the Relativistic Heavy Ion Collider energies while the Xi(-)/h(-) stays approximately constant. A hydrodynamically inspired model fit to the Xi spectra, which assumes a thermalized source, seems to indicate that these multistrange particles experience a significant transverse flow effect, but are emitted when the system is hotter and the flow is smaller than values obtained from a combined fit to pi, K, p, and Lambdas. 相似文献
113.
Ce(NO3)3.6H2O or Pr(NO3)3.6H2O and pyridine-2,6-dicarboxylic acid form a linear coordination polymeric structure under hydrothermal conditions. Hexameric water clusters join these linear chains through bonding to the metal ions. Other coordinated water and the carboxylate oxygen form an intricate array of hydrogen bonding resulting in a 3D network where each metal ion shows 9-coordination with an approximate D3 symmetry. Dimeric water clusters are also located in the void spaces. In the structure containing Pr(III), the water dimers are hydrogen-bonded to the hexamers, whereas in the Ce(III) structure, the dimers and the hexamers are far apart. 相似文献
114.
Field amplified sample stacking (FASS) is used to increase sample concentrations in electrokinetic flows. The technique uses
conductivity gradients to establish a non-uniform electric field that accumulates ions within a conductivity gradient, and
can be readily integrated with capillary electrophoresis. Conductivity gradients also cause gradients in near-wall electroosmotic
flow velocities. These velocity gradients generate internal pressure gradients that drive secondary, dispersive flows. This
dispersion leads to a significant reduction in the efficiency of sample stacking. This paper presents an experimental investigation
of internally generated pressure gradients in FASS using micron-resolution particle image velocimetry (μPIV). We measure velocity
fields of particles seeded into an electrokinetic FASS flow field in a glass microchannel with a single buffer–buffer interface. μPIV
allows for the direct quantification of local, instantaneous pressure gradients by analyzing the curvature of velocity profiles.
Measurements show internally generated pressure-driven velocities on the order of 1mm/s for a typical applied electric field
of 100 V/cm and a conductivity ratio of 10. A one-dimensional (1D) analytical model for the temporal development of the internal
pressure gradient generation is proposed which is useful in estimating general trends in flow dynamics.
相似文献
Juan G. SantiagoEmail: |
115.
Vivek S. Bharadwaj Nathaniel M. Eagan Nicholas M. Wang Prof. Matthew W. Liberatore Prof. C. Mark Maupin 《Chemphyschem》2015,16(13):2810-2817
Despite the importance of fatty‐acid methyl esters (FAMEs) as key components of various green solvents, detergents, plasticizers, and biodiesels, our understanding of these systems at the molecular level is limited. An enhanced molecular‐level perspective of FAMEs will enable a detailed analysis of the polymorph and crystallization phenomena that adversely impact flow properties at low temperatures. Presented here, is the parameterization and validation of a charge‐modified generalized amber force field (GAFF) for eight common FAMEs and two representative biodiesel mixtures. Our simulations accurately reproduce available experimental data (e.g. densities and self‐diffusivity coefficients) and their trends, with respect to temperature and degree of unsaturation. Structural analyses from our simulations provide a more detailed picture of liquid‐phase molecular ordering in FAMEs and confirm recent experimental hypotheses. This study provides a firm foundation to initiate further studies into the mechanisms that drive crystallization phenomena at the molecular level. 相似文献
116.
Crystal structure of the compound L·4H2O (L = aza cryptand) and its supramolecular assembly via H-bonding through water molecules are described here. The compound crystallizes in the cubic space group Pa3 (no. 205) with the following lattice parameters: a=b=c=19.023(2) Å, V=6883.9(4) Å3, Z=8, R 1=0.0592, wR 2 = 0.1572, S=0.964. 相似文献
117.
Somnath Bharadwaj 《Pramana》1999,53(6):977-987
We briefly discuss some aspects of the problem of forming large scale structures in the Universe. The basic picture that initially
small perturbations generated by inflation grow by the process of gravitational instability to give the observed structures
is largely consistent with the observations. The growth of the perturbations depends crucially on the contents of the Universe,
and we discuss a few variants of the cold dark matter model. Many of these models are consistent with present observations.
Future observations hold the possibility of deciding amongst these models. 相似文献
118.
119.
Ce0.8Eu0.2O2?δ was synthesized by conventional solid state route as well as wet chemical route (i.e. cation complexation, combustion method). The crystallite size obtained for cation complexation and combustion samples is 14 and 19 nm while their surface area is 11.70 and 29.63 m2g?1 respectively. Cation complexation synthesized product lead to formation of agglomerates and hence the sintered sample showed porosity compared to combustion synthesized sample. However, despite high packing density the combustion synthesized sample showed lower grain boundary, total conductivity than cation complexation synthesized product due to the formation of siliceous film at the grain boundary. 相似文献
120.
Gayatri Sarmah Saitanya K. Bharadwaj Anindita Dewan Ankur Gogoi Utpal Bora 《Tetrahedron letters》2014
A simple and efficient vanadium based catalyst system for the oxidation of primary and secondary alcohols to aldehydes or ketones is reported using tert-butyl hydroperoxide as oxidizing agent and vanadyl sulfate as catalyst at room temperature. The versatility of the catalytic protocol is studied with wide variety of substrates. 相似文献