全文获取类型
收费全文 | 352624篇 |
免费 | 2527篇 |
国内免费 | 846篇 |
专业分类
化学 | 173651篇 |
晶体学 | 5571篇 |
力学 | 17099篇 |
综合类 | 8篇 |
数学 | 48725篇 |
物理学 | 110943篇 |
出版年
2018年 | 10821篇 |
2017年 | 11630篇 |
2016年 | 7593篇 |
2015年 | 3272篇 |
2014年 | 3655篇 |
2013年 | 10456篇 |
2012年 | 11947篇 |
2011年 | 21773篇 |
2010年 | 13529篇 |
2009年 | 13414篇 |
2008年 | 19245篇 |
2007年 | 22594篇 |
2006年 | 8991篇 |
2005年 | 14911篇 |
2004年 | 10743篇 |
2003年 | 10015篇 |
2002年 | 8007篇 |
2001年 | 8648篇 |
2000年 | 6502篇 |
1999年 | 4953篇 |
1998年 | 3800篇 |
1997年 | 3827篇 |
1996年 | 3813篇 |
1995年 | 3553篇 |
1994年 | 3349篇 |
1993年 | 3140篇 |
1992年 | 3810篇 |
1991年 | 3868篇 |
1990年 | 3675篇 |
1989年 | 3690篇 |
1988年 | 3642篇 |
1987年 | 3654篇 |
1986年 | 3378篇 |
1985年 | 4381篇 |
1984年 | 4541篇 |
1983年 | 3716篇 |
1982年 | 3955篇 |
1981年 | 3670篇 |
1980年 | 3722篇 |
1979年 | 4016篇 |
1978年 | 4205篇 |
1977年 | 3989篇 |
1976年 | 3976篇 |
1975年 | 3769篇 |
1974年 | 3628篇 |
1973年 | 3895篇 |
1972年 | 2455篇 |
1971年 | 1909篇 |
1968年 | 1973篇 |
1967年 | 1850篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
M. Lopez Noriega 《The European Physical Journal C - Particles and Fields》2007,49(1):315-319
The strong suppression of high-pT hadrons observed in heavy ion collisions at RHIC indicates the interaction of high energy partons with a dense colored medium
prior to hadronization. We review the main results from the high-pT hadron analysis at RHIC and what they tell us about the medium. We then concentrate on the new possibilities that the wider
kinematic range at the LHC will offer and how they will help us to better characterize the medium produced in these collisions. 相似文献
972.
973.
In apparel industry, manufacturers developed standard allowed minutes (SAMs) databases on various manufacturing operations in order to facilitate better scheduling, while effective production schedules ensure smoothness of downstream operations. As apparel manufacturing environment is fuzzy and dynamic, rigid production schedules based on SAMs become futile in the presence of any uncertainty. In this paper, a fuzzification scheme is proposed to fuzzify the static standard time so as to incorporate some uncertainties, in terms of both job-specific and human related factors, into the fabric-cutting scheduling problem. A genetic optimisation procedure is also proposed to search for fault-tolerant schedules using genetic algorithms, such that makespan and scheduling uncertainties are minimised. Two sets of real production data were collected to validate the proposed method. Experimental results indicate that the genetically optimised fault-tolerant schedules not only improve the operation performance but also minimise the scheduling risks. 相似文献
974.
S. A. Moiseev 《Optics and Spectroscopy》2003,94(5):788-796
A new variant of realization of quantum memory based on the use of a photon echo in an optically dense three-level gaseous medium is proposed. The use of a long-lived highly excited optical level as a storage of quantum information is the characteristic feature of the scheme proposed. This scheme of quantum memory is distinguished by reduced optical noises owing to the possibility of realizing temporal, spectral, and spatial selection of weak quantum radiation relative to the accompanying laser pulsed fields. 相似文献
975.
V. F. Shkar’ V. P. Denisenkov A. M. Grishin A. A. Yalali S. I. Khartsev E. I. Nikolaev V. N. Sayapin 《Physics of the Solid State》2003,45(12):2334-2337
Bismuth iron garnet films prepared through electron-beam and laser-induced evaporation on (001)-oriented substrates of scandium gallium gadolinium garnet are investigated using ferromagnetic resonance. It is assumed that the additional minima observed in the angular dependence of the resonance field can be associated with the magnetic moment of bismuth ions. 相似文献
976.
977.
Numerical solution of the Slonczewski equations were used to study the motion of an individual domain wall in a two-layer uniaxial film in which the damping parameter and the gyromagnetic ratio depend on the specific layer. 相似文献
978.
Laura Montanaro K. Belgacem P. Llewellyn F. Rouquerol F. Merlo Paola Palmero 《Journal of Thermal Analysis and Calorimetry》2007,88(3):789-793
Wet chemical synthesis of precursor oxide ceramics is a method to obtain small particulate powders. Such powders are far more
prone to ageing in air than more traditional precursors. Thermogravimetric analysis is used to highlight the species responsible
for the ageing of ceramic precursors. Indeed water and carbon dioxide are observed to evolve from aged powders. Ceramics obtained
from aged precursors can reach a very low final density with respect to the theoretical value. A large degree of the original
sintering properties can be recovered after washing the aged powders with ethanol in a basic medium. 相似文献
979.
L. R. Gavrilov 《Acoustical Physics》2003,49(5):508-515
A numerical simulation and a comparative analysis of the acoustic fields produced by two-dimensional phased arrays intended for ultrasonic surgery are performed for the case of a multiple focus (in particular, 25 foci) generation. The calculations were conducted for arrays (with an operating frequency of 1.5 MHz) consisting of 256 elements 5 mm in diameter, which were positioned on the array surface both regularly and randomly. The array foci can be formed simultaneously, but, in this case, the intensity levels of the secondary peaks in the ultrasonic field can exceed the values that guarantee the safe application of this method in surgery. A much safer way is to synthesize many foci with the use of several configurations, each of which contains a smaller number of foci. The number of foci in individual configurations must be approximately the same. It is demonstrated that randomization of the element distribution over the array surface provides an opportunity to improve the array performance, to reduce the intensity levels of secondary peaks in the acoustic field, and to increase the array capability for multiple focus scanning off the array axis. 相似文献
980.
Numerical analysis for stochastic age-dependent population equations with Poisson jumps 总被引:1,自引:0,他引:1
In this paper, stochastic age-dependent population equations with Poisson jumps are considered. In general, most of stochastic age-dependent population equations with jumps do not have explicit solutions, thus numerical approximation schemes are invaluable tools for exploring their properties. The main purpose of this paper is to develop a numerical Euler scheme and show the convergence of the numerical approximation solution to the true solution. 相似文献