全文获取类型
收费全文 | 694篇 |
免费 | 19篇 |
国内免费 | 3篇 |
专业分类
化学 | 320篇 |
晶体学 | 11篇 |
力学 | 9篇 |
数学 | 44篇 |
物理学 | 332篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 18篇 |
2018年 | 16篇 |
2017年 | 9篇 |
2016年 | 19篇 |
2015年 | 15篇 |
2014年 | 21篇 |
2013年 | 55篇 |
2012年 | 32篇 |
2011年 | 47篇 |
2010年 | 25篇 |
2009年 | 33篇 |
2008年 | 38篇 |
2007年 | 31篇 |
2006年 | 33篇 |
2005年 | 27篇 |
2004年 | 22篇 |
2003年 | 16篇 |
2002年 | 22篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 11篇 |
1997年 | 4篇 |
1996年 | 19篇 |
1995年 | 18篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 15篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 14篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1958年 | 1篇 |
1938年 | 2篇 |
排序方式: 共有716条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
35.
Debanjan Bhattacharjee Parameswara Rao Alapati 《Molecular Crystals and Liquid Crystals》2017,648(1):66-76
This article represents the electrical studies of an interdigitated highly skewed N(4-n-pentyloxybenzylidene) 4-n-alkylaniline (5O.16) compound. Interestingly the compound is partially bent like and unsymmetrical in alkyl chain length. Dielectric and impedance spectroscopy studies indicate the coupling between the liquid crystal and the electrical field. Studies were carried out as a function of temperature as well as frequency. Semicircular nature of the Cole–Cole plots indicates the reorientation of the molecule with the applied field. Using the experimental data and the theoretically fitted results the effective equivalent model circuit was designed. Which used to explain the behavior of the compound under the external electric effect and the influence of the electrodes with different variable represent the resistor circuit. However, the effect of the conductivity of temperature and frequency are also reported. 相似文献
36.
We consider the Sel’kov model of glycolytic oscillator for a quantitative study of the limit cycle oscillations in the system.
We identify a region of parameter space where perturbation theory holds and use both Linstedt Poincaré technique and harmonic
balance to obtain the shape and frequency of the limit cycle. The agreement with the numerically obtained result is excellent.
We also find a different extreme, where the limit cycle is of the relaxation oscillator variety, has a large time period and
it is seen that, as a particular parameter in the model is varied, the time period increases indefinitely. We characterize
this divergence numerically. A calculational method is devised to capture the divergence approximately. 相似文献
37.
Abazov VM Abbott B Abdesselam A Abolins M Abramov V Acharya BS Adams DL Adams M Ahmed SN Alexeev GD Alves GA Amos N Anderson EW Baarmand MM Babintsev VV Babukhadia L Bacon TC Baden A Baldin B Balm PW Banerjee S Barberis E Baringer P Barreto J Bartlett JF Bassler U Bauer D Bean A Begel M Belyaev A Beri SB Bernardi G Bertram I Besson A Beuselinck R Bezzubov VA Bhat PC Bhatnagar V Bhattacharjee M Blazey G Blessing S Boehnlein A Bojko NI Borcherding F Bos K Brandt A Breedon R Briskin G Brock R 《Physical review letters》2001,87(6):061802
We present results of searches for technirho (rho(T)), techniomega (omega(T)), and Z' particles, using the decay channels rho(T),omega(T),Z'-->e(+)e(-). The search is based on 124.8 pb(-1) of data collected by the D0 detector at the Fermilab Tevatron during 1992-1996. In the absence of a signal, we set 95% C.L. upper limits on the cross sections for the processes pp-->rho(T),omega(T),Z'-->e(+)e(-) as a function of the mass of the decaying particle. For certain model parameters, we exclude the existence of degenerate rho(T) and omega(T) states with masses below about 200 GeV. We exclude a Z' with mass below 670 GeV, assuming that it has the same couplings to fermions as the Z boson. 相似文献
38.
A. Bhattacharyay J.K. Bhattacharjee 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(1):137-141
Reaction diffusion systems can exhibite both spatial and temporal patterns. We show that the effect of spatial variation of
the removal rate can have significant effect on the stability boundaries. In particular there can be a case of parametric
resonance.
Received 11 March 1998 相似文献
39.
Effects of Hall current on a steady hydromagnetic (MHD) fully developed flow in a rotating environment within a parallel plate
channel in the presence of an inclined magnetic field is studied. From an extension of literature [13] subject to a forced
oscillation it is observed that the present paper is methodically more correct to work first in the steady state where forced
oscillation becomes insignificant and then new results are expected for an unsteady MHD flow under the influence of a pulse-oscillator.
Exact solutions of the governing equations are obtained in a closed form. The graphical representation for the velocity and
the induced magnetic field are depicted graphically and the heat transfer at both the plates are presented in tables. 相似文献
40.
Rajan Kumar Subir Kumar Ray Dr. Saikat Mukherjee Sudipta Saha Dr. Arijit Bag Prof. Dr. Pradip Kr. Ghorai Prof. Dr. Nirmalya Ghosh Prof. Dr. Raja Shunmugam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(59):13514-13522
The development of organic photoluminescent materials, which show promising roles as catalysts, sensors, organic light-emitting diodes, logic gates, etc., is a major demand and challenge for the global scientific community. In this context, a photoclick polymerization method is adopted for the growth of a unique photoluminescent three-dimensional (3D) polymer film, E, as a model system that shows emission tunability over the range 350–650 nm against the excitation range 295–425 nm. The DFT analysis of energy calculations and π-stacking supports the spectroscopic observations for the material exhibiting a broad range of emission owing to newly formed chromophoric units within the film. Full polarization spectroscopic Mueller matrix studies were employed to extract and quantify the molecular orientational order of both the ground (excitation) and excited (emission) state anisotropies through a set of newly defined parameters, namely the fluorescence diattenuation and fluorescence polarizance. The information contained in the recorded fluorescence Mueller matrix of the organic polymer material provided a useful way to control the spectral intensity of emission by using pre- and post-selection of polarization states. The observation was based on the assumption that the longer lifetime of the excited dipolar orientation is attributed to the compactness of the film. 相似文献