全文获取类型
收费全文 | 149篇 |
免费 | 6篇 |
专业分类
化学 | 99篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 19篇 |
物理学 | 35篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 1篇 |
2014年 | 11篇 |
2013年 | 12篇 |
2012年 | 16篇 |
2011年 | 10篇 |
2010年 | 9篇 |
2009年 | 4篇 |
2008年 | 12篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2001年 | 1篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有155条查询结果,搜索用时 15 毫秒
21.
We obtain approximate solutions of Altarelli-Parisi equations beyond leading logarithmic approximation. Our results suggest
quantitative utility of higher order terms in the structure function analysis of deep inelastic scattering. 相似文献
22.
Let G be a finite group G, K a field of characteristic p ≥ 17 and let U be the group of units in KG. We show that if the derived length of U does not exceed 4, then G must be abelian. 相似文献
23.
Das MR Sarma RK Saikia R Kale VS Shelke MV Sengupta P 《Colloids and surfaces. B, Biointerfaces》2011,83(1):16-22
A solution-based approach to the synthesis of silver (Ag) nanoparticles by chemical reduction of AgNO(3) in a graphene oxide (GrO) suspension is demonstrated. X-ray diffraction and transmission electron microscopy indicate that the Ag nanoparticles, of size range 5-25nm, were decorated on the GrO sheets. The size and shape of the Ag nanoparticles are dependent on the concentration of the AgNO(3) solution. Antimicrobial activity of such hybrids materials is investigated against the Gram negative bacteria Escherichia coli and Pseudomonous aeruginosa. The bacterial growth kinetics was monitored in nutrient broth supplemented with the Ag nanoparticle-GrO suspension at different conditions. It was observed that P. aeruginosa is comparatively more sensitive to the Ag nanoparticle-GrO suspension. 相似文献
24.
A simple method has been applied to solve the approximate gluon evolution equation for small-x at fixedρ(≡√ln(x
0/x)/ln[ln(Q
2/Λ2)/ln(Q
0
2
/Λ2)]. Numerical comparison is made with the predictions from ‘double asymptotic scaling’ and fit. Better agreement is found
between our solution and fit nearρ=1. The solution gives approximate double scaling in this region having ‘hard’ pomeron with small contamination. 相似文献
25.
We found an approximate simple solution of sea-quark evolution equation in terms ofρ(=√ln(x
0/x)/ln[ln(Q
2/Λ2)/(Q
0
2
/Λ2)]) andζ(≡ln[ln(Q
2Λ2)/ln(Q
0
2
/Λ2)]) in the small-x region whenρ is fixed and compared with HERA data. Agreement with data is found for largeQ
2 and smallρ. Comparison with double asymptotic scaling prediction is made. We found a critical value ofρ. More data are needed to confirm this point. 相似文献
26.
A theoretical study is made on the generation mechanism of Langmuir mode wave in the presence of kinetic Alfvén wave turbulence
in a magnetized plasma on the basis of plasma-maser interaction. It is shown that a test high frequency Langmuir mode wave
is unstable in the presence of low frequency kinetic Alfvén wave turbulence. The growth of the Langmuir wave occurs due to
direct and polarization coupling terms. Because of the universal existence of the kinetic Alfvén waves in large scale plasmas,
the results have potential importance in space and astrophysical radiation processes. 相似文献
27.
Biren Gohain Bornali Boruah Palash M. Saikia Robin K. Dutta 《Journal of Physical Organic Chemistry》2010,23(3):211-219
The premicellar and micelle formation behaviors of four cationic triphenylmethane dyes, viz, Pararosaniline (RN), Crystal violet (CV), Ethyl violet (EV), and Malachite green (MG), in aqueous anionic surfactant solutions of sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), and sodium dodecyl sulfonate (SDSN) have been studied by spectral and surface tension measurements. The study was carried out within a pH range where the dyes are stable in their quinoid forms. The dyes have been found to form dye–surfactant ion pairs (DSIPs) with the surfactants, at the surfactant concentrations well below their critical micelle concentration, CMC*. The DSIPs behave like nonionic surfactants and form an air–water interfacial monolayer. The DSIPs have a lower critical micelle concentration (CMCIP), greater efficiency, and lower effectiveness than the corresponding pure surfactants. As the surfactant concentration is increased below the CMC*, the DSIPs start forming micelles of their own where the dye gets protonated and exists as a protonated dye–surfactant ion pair (PDSIP) in the ion pair micelles. As the concentration of the surfactant exceeds the CMC* of the pure surfactant, the protonation reverses gradually with the dye remaining in the micelles in solubilized form and the DSIPs in the air–water interfacial monolayer are replaced by pure surfactants. The distorted helical isomeric form (isomer B) of the dyes is favored in the PDSIPs. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
28.
A generalized expression is used on the basis of relaxation time approximation to facilitate calculation of lattice thermal
conductivity of dielectric materials as well as skutterudite family consists of compounds of the form AB3. It is assumed that phonon scattering processes are independent and is represented by frequency dependent relaxation times.
The contributions of normal three phonon scattering processes are included explicitly as redistribution of phonon momentum
between two oscillation branches is considered. Magnitudes of relaxation times are estimated from the experimental data. The
result for CoSb3 is in reasonably good agreement with the experimental result in the temperature range 1–1000°K. It is observed that redistribution
of phonon momentum between two oscillation branches leads to a significant suppression of thermal conductivity maximum and
it is observed that for unfilled skutterudite the main dominant mechanism at the thermal conductivity maximum is three phonon
normal scattering process. 相似文献
29.
We derive a new special case C(q) of a general continued fraction recorded by Ramanujan in his Lost Notebook. We give a representation of the continued fraction C(q) as a quotient of Dedekind eta-function and then use it to prove modular identities connecting C(q) with each of the continued fractions \(C(-q)\), \(C(q^{2})\), \(C(q^{3})\), \(C(q^{5})\), \(C(q^{7})\), \(C(q^{11})\), \(C(q^{13})\) and \(C(q^{17})\). We also prove general theorems for the explicit evaluation of the continued fraction C(q) by using Ramanujan’s class invariants. 相似文献
30.
Summary: In this work, an attempt was made to synthesize a novel Chitosan-Mesoporous silica (CS-MS) hybrid composite to design a drug delivery system based on ultrasound triggered stimuli-responsive smart release. The in-vitro drug release properties of both the Mesoporous Silica (MS) and Chitosan (CS) hybrids were investigated. Ibuprofen (Ibu) was used as a model drug. The results from powder X-Ray diffraction (XRD) patterns, and BET N2 adsorption isotherms exhibited that MS can accommodate drug molecules into the lumen of the channels and pores. Drug release, stimulated by temperature and pH of the release media was also investigated. We studied the Ultrasound (US) triggered release of Ibu in a simulated body fluid (pH 7.4). The results exhibited that US can be used as a non-invasive technique for drug release from polymeric materials. The enhancing effect of ultrasound on drug release is due to the Cavitation effect, without causing any significant destruction on the polymer morphology. 相似文献