全文获取类型
收费全文 | 622776篇 |
免费 | 6364篇 |
国内免费 | 1739篇 |
专业分类
化学 | 331972篇 |
晶体学 | 9291篇 |
力学 | 28099篇 |
综合类 | 20篇 |
数学 | 74828篇 |
物理学 | 186669篇 |
出版年
2021年 | 4854篇 |
2020年 | 5532篇 |
2019年 | 6006篇 |
2018年 | 7875篇 |
2017年 | 7735篇 |
2016年 | 11825篇 |
2015年 | 7400篇 |
2014年 | 11379篇 |
2013年 | 27722篇 |
2012年 | 21062篇 |
2011年 | 25776篇 |
2010年 | 18238篇 |
2009年 | 17898篇 |
2008年 | 23846篇 |
2007年 | 23861篇 |
2006年 | 22130篇 |
2005年 | 19920篇 |
2004年 | 18418篇 |
2003年 | 16417篇 |
2002年 | 16247篇 |
2001年 | 17945篇 |
2000年 | 13811篇 |
1999年 | 10848篇 |
1998年 | 9167篇 |
1997年 | 8947篇 |
1996年 | 8599篇 |
1995年 | 7812篇 |
1994年 | 7809篇 |
1993年 | 7441篇 |
1992年 | 8443篇 |
1991年 | 8460篇 |
1990年 | 8157篇 |
1989年 | 7825篇 |
1988年 | 8004篇 |
1987年 | 7780篇 |
1986年 | 7388篇 |
1985年 | 9621篇 |
1984年 | 9941篇 |
1983年 | 8137篇 |
1982年 | 8275篇 |
1981年 | 8185篇 |
1980年 | 7827篇 |
1979年 | 8165篇 |
1978年 | 8550篇 |
1977年 | 8377篇 |
1976年 | 8406篇 |
1975年 | 7701篇 |
1974年 | 7820篇 |
1973年 | 7960篇 |
1972年 | 5626篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
T. M. Tovstik 《Vestnik St. Petersburg University: Mathematics》2007,40(3):250-252
An algorithm for calculating the discrepancy of finitely many points in the unit n-cube [0, 1]n is suggested. This algorithm is easy to program. For 2 ≤ n ≤ 4, the suggested algorithm is significantly faster than Bundschuh and Zhu’s algorithm. For larger n, whether this algorithm is faster depends on the number of points. 相似文献
942.
I.G. Goryacheva 《Physical Mesomechanics》2007,10(5-6):247-254
943.
The dynamical Casimir effect is analyzed in the framework of the S-matrix formulation for a one-dimensional cavity that exhibits contraction at a constant rate over a finite time interval. The exact solution to the problem is presented. It is demonstrated that the efficiency of the creation of pairs nonmonotonically depends on the contraction time. This is due to the fact that the particles are only created at the moments corresponding to the acceleration and stopping of the moving boundary, so that the contributions of these processes on the number of the created particles interfere with each other. The parameters that correspond to the optimal creation of pairs and the stability of a vacuum are presented. The effect of the finiteness of the cavity-boundary acceleration on the results obtained is studied. 相似文献
944.
Yu. V. Kaletina V. M. Schastlivtsev E. A. Fokina 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(12):1667-1673
The effect of magnetic treatment on the isothermal martensitic transformation in the Fe-24% Ni-4% Mn alloy has been investigated. The martensitic transformation in a dc magnetic field at liquid-helium temperature has been analyzed. 相似文献
945.
V. I. Zubkov I. S. Shulgunova A. V. Solomonov M. Geller A. Marent D. Bimberg A. E. Zhukov E. S. Semenova V. M. Ustinov 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(1):106-108
In this work, charge-carrier capture by an array of self-assembled InAs/GaAs quantum dots was directly observed for the first time by capacitance recharge. It is proposed to process the obtained transient-capture data by a similar method to that used for emission, by the box-car method. The capture activation energies are determined and compared with the emission activation energies. 相似文献
946.
L. A. Bityutskaya V. V. Distler V. V. Kryachko M. A. Yudovskaya M. V. Grechkina E. V. Bogatikov 《Physics of the Solid State》2007,49(7):1382-1386
Nanostructuring of natural isoferroplatinum crystals is revealed by atomic-force microscopy for the first time. Typical scales of ~30, 50, and 100 nm are determined and the self-affine character of their relation is established using a wavelet analysis. 相似文献
947.
Ph. Komninou Th. Kehagias A. Delimitis G.P. Dimitrakopulos J. Kioseoglou E. Dimakis A. Georgakilas Th. Karakostas 《Superlattices and Microstructures》2004,36(4-6):509
The structural properties of InN thin films, grown by rf plasma-assisted molecular beam epitaxy on Ga-face GaN/Al2O3(0001) substrates, were investigated by means of conventional and high resolution electron microscopy. Our observations showed that a uniform InN film of total thickness up to 1 μm could be readily grown on GaN without any indication of columnar growth. A clear epitaxial orientation relationship of , was determined. The quality of the InN film was rather good, having threading dislocations as the dominant structural defect with a density in the range of 109–1010 cm−2. The crystal lattice parameters of wurtzite InN were estimated by electron diffraction analysis to be a=0.354 nm and c=0.569 nm, using Al2O3 as the reference crystal. Heteroepitaxial growth of InN on GaN was accomplished by the introduction of a network of three regularly spaced misfit dislocation arrays at the atomically flat interface plane. The experimentally measured distance of misfit dislocations was 2.72 nm. This is in good agreement with the theoretical value derived from the in-plane lattice mismatch of InN and GaN, which indicated that nearly full relaxation of the interfacial strain between the two crystal lattices was achieved. 相似文献
948.
Sanzhizhapov D. B. Tonevitskii Yu. V. Mognonov D. M. Doroshenko Yu. E. 《Russian Journal of Applied Chemistry》2003,76(4):619-622
New polyimidates were prepared from bisphenols and mono- and dicarboxylic acid imidoyl chlorides. The structures of the polymers were determined, and their physicochemical, chemical, and thermal properties were studied. The possibility of preparing film and compression materials with good mechanical characteristics from these polymers was examined. 相似文献
949.
V. G. Sutyrin 《Journal of Applied Mathematics and Mechanics》1991,55(6):877-886
The stress relaxation process is linked to the change with time of the metric stress tensor of the medium. Possible types of thermodynamically justified relaxation equations are discussed. 相似文献
950.
A. M. Hashimov Sh. M. Hasanli R. N. Mehdizadeh Sh. M. Azizova Kh. B. Bayramov 《Technical Physics》2007,52(8):1086-1088
The resistivity of composite nonlinear resistors (varistors) consisting of zinc oxide ceramic and high-density polyethylene, as well as IR spectra and X-ray diffraction patterns taken of the samples, are studied. The component composition of the resistor is shown to influence its resistivity and IR and X-ray spectra. 相似文献