全文获取类型
收费全文 | 2422篇 |
免费 | 128篇 |
国内免费 | 16篇 |
专业分类
化学 | 1636篇 |
晶体学 | 30篇 |
力学 | 47篇 |
数学 | 434篇 |
物理学 | 419篇 |
出版年
2023年 | 28篇 |
2022年 | 59篇 |
2021年 | 65篇 |
2020年 | 59篇 |
2019年 | 86篇 |
2018年 | 77篇 |
2017年 | 83篇 |
2016年 | 111篇 |
2015年 | 83篇 |
2014年 | 141篇 |
2013年 | 210篇 |
2012年 | 174篇 |
2011年 | 178篇 |
2010年 | 121篇 |
2009年 | 98篇 |
2008年 | 144篇 |
2007年 | 126篇 |
2006年 | 114篇 |
2005年 | 82篇 |
2004年 | 79篇 |
2003年 | 68篇 |
2002年 | 60篇 |
2001年 | 26篇 |
2000年 | 27篇 |
1999年 | 23篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 13篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1966年 | 6篇 |
1961年 | 5篇 |
排序方式: 共有2566条查询结果,搜索用时 31 毫秒
1.
2.
G Padmaja A V Ravi Kumar V Vidyalal P Radhakrishnan V P N Nampoori C P G Vallabhan 《Pramana》1989,32(5):L693-L698
Laser induced plasma emission spectra from highT
c superconducting samples of YBa2Cu3O7 and GdBa2Cu3O7 obtained with 1.06μm radiation from a Q switched Nd:YAG laser beam has been analysed. The results clearly show the presence of diatomic oxides
in addition to ionized species of the constituent metals in the plasma thus produced. 相似文献
3.
Alvaro Carrillo Ravi S. Kane 《Journal of polymer science. Part A, Polymer chemistry》2004,42(13):3352-3359
This article describes the formation and characterization of self‐assembled nanoparticles of controlled sizes based on amphiphilic block copolymers synthesized by ring‐opening metathesis polymerization. We synthesized a novel hydrophobic derivative of norbornene; this monomer could be polymerized using Grubbs' catalyst [Cl2Ru(CHPh)(PCy3)2] forming polymers of controlled molecular weight. We synthesized amphiphilic block copolymers of controlled composition and showed that they assemble into nanoparticles of controlled size. The nanoparticles were characterized using dynamic light scattering and transmission electron microscopy. Tuning the composition of the block copolymer enables the tuning of the diameters of the nanoparticles in the 30‐ to 80‐nm range. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3352–3359, 2004 相似文献
4.
Y.P. Venkata Subbaiah 《Applied Surface Science》2006,253(5):2409-2415
ZnS films have been deposited on glass substrates by close-spaced evaporation (CSE) technique. The films were grown at different temperatures in the range, 200-350 °C. The layers have been characterized with X-ray diffractometer (XRD), atomic force microscope (AFM), energy dispersive analysis of X-rays (EDAX) and optical spectrophotometer to evaluate the quality of the layers for photovoltaic applications. The studies showed that the optimum substrate temperature for the growth of ZnS layers was 300 °C. The films grown at these temperatures exhibited cubic structure with nearly stoichiometric composition. The AFM data revealed that the films had nano-sized grains with a grain size of ∼40 nm. The optical studies exhibited direct allowed transition with an energy band gap of 3.61 eV. The other structural and optical parameters such as lattice stress, dislocation density, refractive index and extinction coefficient were also evaluated. The temperature-dependent conductivity measured in the range, 303-523 K showed a change in the conduction mechanism at 120 °C. The activation energy values evaluated using the temperature dependence of electrical conductivity are 7 and 29 meV at low and high temperature regions, respectively. 相似文献
5.
Arup Baksi Bidyut Kumar Roy Rasajit Kumar Bera 《Mathematical and Computer Modelling》2006,44(11-12):1069-1079
The fundamental equations of the problems of generalized thermoelasticity with one relaxation parameter including heat sources in infinite rotating magneto-thermo-viscoelastic media have been derived in the form of a vector matrix differential equation in the Laplace transform domain for a one dimensional problem. These equations have been solved by the eigenvalue approach to determine deformations, stress, and temperature. The results have been compared to those available in the existing literature. The graphs have been drawn to show the effect of rotation in the medium. 相似文献
6.
7.
Leong‐Huat Gan Palaniswamy Ravi Bao Wei Mao Kam‐Chiu Tam 《Journal of polymer science. Part A, Polymer chemistry》2003,41(17):2688-2695
Polymerization of 2‐(diethylamino)ethyl methacrylate (DEAEMA) via homogeneous atom transfer radical polymerization under various reaction conditions is described. The effects of the initiators and solvents were examined. With 1,1,4,7,10,10‐hexamethyl triethylenetetramine/copper(I) chloride/p‐toluenesulfonyl chloride as the ligand/catalyst/initiator system in methanol, poly(DEAEMA) with a polydispersity index as low as 1.07 was synthesized. Kinetic studies demonstrated the polymerization was very well controlled and exhibited the living characteristic of the process. Well‐defined block copolymers of DEAEMA and tert‐butyl methacrylate (tBMA) were successfully synthesized. The copolymers could be synthesized with equally good results by starting with either p(DEAEMA) or p(tBMA) as the macroinitiators. However, only the macroinitiators terminated with chlorine should be used. The corresponding macroinitiators with bromine as a transferable group did not yield well‐defined copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2688–2695, 2003 相似文献
8.
9.
We have given design of a very small residual dispersion fiber system consisting of a small dispersion fiber(SDF) with flat modal field and a corresponding dual core coaxial dispersion compensating fiber (DCF). 相似文献
10.
A graphite electrode modified with cobalt hexacyanoferrate by mechanical immobilization was used for amperometric determination of hydrazine. The modified electrode exhibits good catalytic activity for the oxidation of hydrazine at a reduced overpotential with remarkable sensitivity. The modified electrode showed a linear response for hydrazine in the concentration range of 2.0 × 10–5 to 2.8 × 10–4 M. The detection limit was 9.8 × 10–6 M (S/N = 3). The proposed modified electrode was simple, sensitive, rapid, stable and promising. 相似文献