全文获取类型
收费全文 | 529篇 |
免费 | 16篇 |
专业分类
化学 | 272篇 |
晶体学 | 9篇 |
力学 | 32篇 |
数学 | 59篇 |
物理学 | 173篇 |
出版年
2022年 | 10篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 4篇 |
2017年 | 19篇 |
2016年 | 14篇 |
2015年 | 6篇 |
2014年 | 20篇 |
2013年 | 54篇 |
2012年 | 17篇 |
2011年 | 19篇 |
2010年 | 28篇 |
2009年 | 19篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 16篇 |
2005年 | 20篇 |
2004年 | 6篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 12篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1969年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有545条查询结果,搜索用时 15 毫秒
61.
Chauhan Varsha Sharma Anuradha Sharma Sandeep Yadav Monika 《Designs, Codes and Cryptography》2021,89(8):1787-1837
Designs, Codes and Cryptography - Let $${\mathbb {F}}_q$$ denote the finite field of order q, and let $$n = m_1+m_2+\cdots +m_\ell ,$$ where $$m_1,m_2,\ldots ,m_\ell $$ are arbitrary... 相似文献
62.
We study CP violation in a multi-Higgs doublet model based on aS
3×Z
3 horizontal symmetry. We consider two mechanisms for CP violation in this model: a) CP violation due to complex Yukawa couplings;
and b) CP violation due to scalarpseudoscalar mixings. We find that the predictions for ε′/ε, CP violation in B decays and
the electric dipole moments of neutron and electron are different between these two mechanisms. These predictions are also
dramatically different from the minimal Standard Model predictions. 相似文献
63.
S. Deshpande G. Hofstra R. A. Fletcher E. W. Abrahamson 《Photochemistry and photobiology》1991,54(3):485-488
Light scattering relaxation spectrophotometry has proven to be a useful technique to monitor rapid cytophysical changes in chloroplast suspensions brought about by flash illumination. This paper compares the Mg-ATP dependent light scattering behaviour of cholorplasts isolated from control and triazole-treated wheat seedlings. Our results suggest that triazole-treatment enhances Mg-ATP dependent activity. This same enhancement in control chloroplasts can be brought about by introducing potassium ion in the presence of valinomycin. Therefore, the potassium ion might account for part of the stress resistance conferred by triazole treatment. 相似文献
64.
V. K. Deshpande 《Ionics》2004,10(1-2):20-26
The electrical conductivity results of lithium borosilicate glasses with addition of Li2SO4 and LiCl have been critically analyzed. In general, it is observed that the factors viz. lithium fraction, fLi and the number of non-bridging oxygens (NBOs) govern the ionic conductivity in the lithium conducting glasses. For the same
fLi, the presence of mixed formers in the glass gives higher conductivity compared to that of the glass with only one former.
Thus the competitive network of glass in mixed former systems provides higher mobilities for lithium ions and hence high ionic
conductivity. The addition of Li2SO4 and LiCl in the lithium borosilicate glasses gave enhancement in the conductivity. However, the mechanism of enhancement
in conductivity is different in the two glass systems. The comparison of the result of binary, ternary and quaternary glass
systems suggests that in general, the decrease in activation energy, increase in fLi and increase in NBOs gives rise to enhancement in conductivity. For the same value of fLi the higher conductivity is exhibited by glasses with lower value of K (K=SiO2/B2O3).
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
65.
Chuen‐Jinn Tsai Jyh‐Shyan Lin C. G. Deshpande Li‐Chun Liu 《Particle & Particle Systems Characterization》2005,22(5):293-298
An aerosol charge analyzer has been constructed to measure the charge distribution of NaCl particles generated in the laboratory. A radioactive electrostatic charge neutralizer utilizing Po‐210 was used to neutralize the electrostatic charge of the particles. The atomization technique was used to generate NaCl particles with diameters of 0.2 to 0.8 μm, while the evaporation and condensation method was adopted to generate particles of 0.01 to 0.2 μm in diameter. The experimental data demonstrates that the absolute average particle charge depends on the particle diameter, and is higher than that calculated by the Boltzmann charge equilibrium for particles within the range of 0.2 to 0.8 μm. The charge increases with decreasing NaCl concentration. When these particles are neutralized using the Po‐210 neutralizer, it is found that the electrostatic charge reaches the Boltzmann charge equilibrium. For 0.01 to 0.2 μm NaCl particles generated using the evaporation and condensation method, test results show that the absolute average particle charge is higher than that calculated by the Boltzmann charge equilibrium for particles larger than 0.03 to 0.05 μm in diameter, while it is lower than that predicted by the Fuchs theory [1], for particles smaller than 0.03 to 0.05 μm. However, after charge neutralization, particles with diameter above 0.05 μm reach the Boltzmann charge equilibrium condition, and the charges for particles with diameters of 0.010 to 0.05 μm, agree well with Fuchs' theory. 相似文献
66.
Z-scan studies on porphyrin derivative 总被引:2,自引:0,他引:2
K. Kandasamy K. Divakar Rao Rekha Deshpande P.N. Puntambekar Bhanu P. Singh Shankar J. Shetty T.S. Srivastava 《Applied physics. B, Lasers and optics》1997,64(4):479-484
Received: 10 January 1996 / Revised version: 15 June 1996 相似文献
67.
It has been shown in this paper that a test proposed by Barlow and Doksum (1972) based on the exponential scores statistic for testing exponentiality against increasing failure rate distributions is consistent for the much wider class of harmonic new better than used in expectation distributions. 相似文献
68.
We present a grand unified model of the strong, electromagnetic and weak interactions based on a local SU(8)L×SU(8)R gauge theory which possesses a global U(8)L × U(8)R invariance. We break the symmetry down to the standard SU(3)C × SU(2)L × U(1) model, with the proton remaining stable and the left-handed neutrinos obliged to remain massless. A novel feature of our model is the simultaneous absence of both strong CP violations and of axions. 相似文献
69.
On application of dc electric fields to a sample of KNO2 (99.9% pure) fused between two heavily nickel plated copper plates the sample does not acquire the potential difference equal
to the applied emf even though there is no external potential drop in the circuit. Also a very large capacitance of the order
of 3000μF is obtained for this sample which is attributed to interfacial polarization effect. An equivalent circuit is given to explain
the dc electrical behaviour of the sample. The idea of solid state battery does not seem to be applicable in the case of fused
KNO2. The large value of the capacitance for dc fields in series with large voltage-dependent resistance is the cause of the slow
discharge of the condenser. 相似文献
70.
N. Deshpande 《Physics letters. [Part B]》1980,90(4):431-435
In the valence-quark c-decay scheme the decay is expected to be strongly suppressed. We suggest that final state soft gluon exchange may account for the rather large branching ratio recently measured for this process, and study two-body decays of charmed mesons in our new scheme. 相似文献