全文获取类型
收费全文 | 168096篇 |
免费 | 5914篇 |
国内免费 | 4736篇 |
专业分类
化学 | 92596篇 |
晶体学 | 2425篇 |
力学 | 8592篇 |
综合类 | 323篇 |
数学 | 19185篇 |
物理学 | 55625篇 |
出版年
2022年 | 2238篇 |
2021年 | 2846篇 |
2020年 | 3122篇 |
2019年 | 3398篇 |
2018年 | 4193篇 |
2017年 | 4145篇 |
2016年 | 5281篇 |
2015年 | 3272篇 |
2014年 | 4929篇 |
2013年 | 7848篇 |
2012年 | 7649篇 |
2011年 | 8235篇 |
2010年 | 6499篇 |
2009年 | 6540篇 |
2008年 | 7118篇 |
2007年 | 6701篇 |
2006年 | 6280篇 |
2005年 | 5509篇 |
2004年 | 5024篇 |
2003年 | 4547篇 |
2002年 | 4688篇 |
2001年 | 4555篇 |
2000年 | 3445篇 |
1999年 | 2728篇 |
1998年 | 2553篇 |
1997年 | 2259篇 |
1996年 | 2096篇 |
1995年 | 1814篇 |
1994年 | 1876篇 |
1993年 | 1819篇 |
1992年 | 1844篇 |
1991年 | 1949篇 |
1990年 | 1890篇 |
1989年 | 1831篇 |
1988年 | 1654篇 |
1987年 | 1600篇 |
1986年 | 1561篇 |
1985年 | 1699篇 |
1984年 | 1800篇 |
1983年 | 1562篇 |
1982年 | 1582篇 |
1981年 | 1387篇 |
1980年 | 1307篇 |
1979年 | 1495篇 |
1978年 | 1636篇 |
1977年 | 1645篇 |
1976年 | 1668篇 |
1975年 | 1526篇 |
1974年 | 1571篇 |
1973年 | 1542篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
91.
92.
The normal form of certain polynomial matrices is found.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 175, pp. 63–68, 1989. 相似文献
93.
94.
A. A. Berezhnoy F. L. Vladimirov I. Yu. Grodetskii Yu. L. Korzinin V. I. Sukhanov 《Optics and Spectroscopy》2002,93(5):777-780
The possibility of usage of the spontaneous electrooptical (EO) effect in strontium barium niobate (SBN) crystals for the creation of controlled electroholographic elements is studied. It is found that unipolar EO properties of these crystals with respect to switching their spontaneous polarization make it possible to devise field-controlled holographic elements with reversible energy-independent memory for spatial position of an optical beam. 相似文献
95.
Russian Journal of General Chemistry - 相似文献
96.
V. T. Plaksiy O. N. Suchoruchko B. P. Yefimov A. P. Kasyanenko 《International Journal of Infrared and Millimeter Waves》2002,23(4):645-650
Bismuth, antimony and its alloys are the typical representatives of a class of semimetals, which electric conductance is lower in 102-103 times, than of usual well conducting an electrical current metals. The alloys bismuth with antimony have semi-conductor properties in wide area of compositions at temperatures below 77 °K. The semimetals are rather perspective materials from the point of view of their probable application in various devices [1,2,3].In present time the semimetal alloys BiSb have wide application in thermoelectric generators and refrigerators. In work [3] the opportunity of use of semimetals BiSb with percentage content of Bi and Sb from 8 % up to 25 % was shown as high-sensitivity and of small inertion indicators of the mm range radiation where thermoelectric effect is used. The principle of action of such indicators is based on occurrence of temperature gradient in a semimetal crystal BiSb that has two contacts of the various area with flowing electrical current. Basic element of such device is the dot contact metal - semimetal. One of the main characteristics is volt-watt sensitivity of metal-semimetal BiSb contact which calculating is shown in present work. 相似文献
97.
Yu. A. Zarubin 《Fluid Dynamics》1991,26(1):75-81
A displacement model constructed on the assumption of the exchange of components between the volumes of the pore space moving and not moving in the direction of displacement is considered. The theoretical solution is shown to be in good agreement with the actual results of the displacement of oil by water. Criterial equations for predicting the interphase exchange coefficient and the relation between the nonmoving and moving volumes of the pore space are constructed on the basis of a series of experiments in uncemented porous media.Translated from Izvestiya Akademii Nauk SSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 91–97. January–February, 1991. 相似文献
98.
S. N. Vorob'ev Yu. B. Nechaev S. L. Prosvirnin 《Radiophysics and Quantum Electronics》1992,35(8):440-451
The mutual coupling of the radiating elements in microstrip antennas is studied using a rigorous electrodynamic approach in which the field singularities at the radiator edges are taken into account with analytic accuracy. A spectral method is employed in combination with a method of semi-inversion by extraction of the Green-function singularity. The degree of interaction of the elements of microstrip structures at the fundamental and higher current harmonicsis determined, and the applicability of various approximations is assessed.Radio-Astronomy Institute, Academy of Sciences of Ukraine. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 8, pp. 688–701, August, 1992. 相似文献
99.
100.
An approach is proposed to solving multipoint boundary-value problems for linear differential equation of w-th order, based on reduction to two-point boundary-value problems. The two-point problems are solved by the stable discrete orthogonalization method. Some numerical examples are considered.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 58, pp. 36–45, 1986. 相似文献