全文获取类型
收费全文 | 294979篇 |
免费 | 6875篇 |
国内免费 | 4991篇 |
专业分类
化学 | 150610篇 |
晶体学 | 4421篇 |
力学 | 15545篇 |
综合类 | 300篇 |
数学 | 52180篇 |
物理学 | 83789篇 |
出版年
2020年 | 2106篇 |
2019年 | 2227篇 |
2018年 | 12215篇 |
2017年 | 12038篇 |
2016年 | 9346篇 |
2015年 | 3798篇 |
2014年 | 4306篇 |
2013年 | 10135篇 |
2012年 | 11246篇 |
2011年 | 19115篇 |
2010年 | 11716篇 |
2009年 | 11880篇 |
2008年 | 14153篇 |
2007年 | 16251篇 |
2006年 | 7737篇 |
2005年 | 7949篇 |
2004年 | 7367篇 |
2003年 | 7059篇 |
2002年 | 5962篇 |
2001年 | 6630篇 |
2000年 | 5194篇 |
1999年 | 4118篇 |
1998年 | 3262篇 |
1997年 | 3211篇 |
1996年 | 3172篇 |
1995年 | 2876篇 |
1994年 | 2691篇 |
1993年 | 2538篇 |
1992年 | 2970篇 |
1991年 | 2851篇 |
1990年 | 2777篇 |
1989年 | 2778篇 |
1988年 | 2707篇 |
1987年 | 2692篇 |
1986年 | 2515篇 |
1985年 | 3359篇 |
1984年 | 3340篇 |
1983年 | 2766篇 |
1982年 | 2966篇 |
1981年 | 2886篇 |
1980年 | 2804篇 |
1979年 | 2942篇 |
1978年 | 3171篇 |
1977年 | 2978篇 |
1976年 | 2909篇 |
1975年 | 2767篇 |
1974年 | 2712篇 |
1973年 | 2741篇 |
1968年 | 1939篇 |
1967年 | 2140篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
311.
312.
313.
The vibrational dynamics of protein folding is analyzed in the framework of Tsallis statistics. We employ exact expressions
for classical harmonic oscillators by considering the unnormalized constraints. As q→1, we show that these approximations agree with the result of Gaussian network model. 相似文献
314.
R. Hefelmann P. Mann A. Aignan F. Filsinger und H. Amsel 《Fresenius' Journal of Analytical Chemistry》1902,41(1):66-68
Ohne Zusammenfassung 相似文献
315.
A parallel method for time discretization of parabolic equations based on Laplace transformation and quadrature 总被引:5,自引:0,他引:5
We consider the discretization in time of an inhomogeneous parabolicequation in a Banach space setting, using a representation ofthe solution as an integral along a smooth curve in the complexleft half-plane which, after transformation to a finite interval,is then evaluated to high accuracy by a quadrature rule. Thisreduces the problem to a finite set of elliptic equations withcomplex coefficients, which may be solved in parallel. The paperis a further development of earlier work by the authors, wherewe treated the homogeneous equation in a Hilbert space framework.Special attention is given here to the treatment of the forcingterm. The method is combined with finite-element discretizationin spatial variables. 相似文献
316.
Vinod Kumar Pragya Das R.P. Singh S. Muralithar R.K. Bhowmik 《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):153-157
The fusion evaporation reaction 122Sn(14N, 4n)132La was used to populate the high-spin states of 132La at the beam energy of 60 MeV. A new band consisting of mostly E2 transitions has been discovered. This band has the interesting links to the ground state 2- and the isomeric state 6-. A new transition of energy 351 keV connecting the low-spin states of the positive-parity band based on the πh
11/2 ⊗ νh
11/2 particle configuration, has been found. This has played a very important role in resolving the existing ambiguities and inconsistencies
in the spin assignment of the band head.
Received: 12 August 2002 / Accepted: 18 March 2003 / Published online: 7 May 2003 相似文献
317.
The results of a numerical study are described in which the interactions of a primary shock wave with a secondary diaphragm
in expansion tubes are taken into account. The developing wave pattern in the interacting process of the shock with a secondary
diaphragm are visualized by many kinds of figures (e.g., the time-distance diagrams of the wave phenomena on the axis, the
acoustic impedance contours, and the time histories of the pitot pressure on the axis), and the influences of the shape and
rupture process of the diaphragm on the quality of the test gas are explored. 相似文献
318.
V. Balek T. Mitsuhashi I.M. Bountseva H. Haneda Z. Malek J. Šubrt 《Journal of Sol-Gel Science and Technology》2003,26(1-3):185-189
The diffusion structural analysis (DSA) was used to characterize microstructure changes of hydrous titania gel films under in situ conditions of heating. TG and DTA were used in order to elucidate the processes controlling the formation of anatase film during heating of hydrous titania gel film. The annealing of porosity and near surface structure defects of the dehydrated titania films was indicated by DSA in the temperature range 255–700°C as the decrease of radon release rate. It was demonstrated that the annealing was enhanced on heating in oxygen in comparison with heating in argon. The DSA experimental results were compared with model curves describing the radon diffusion mobility and the annealing of radon diffusion paths. 相似文献
319.
320.
A T Brint 《The Journal of the Operational Research Society》2003,54(11):1177-1188
The annual turnover of online auctions is already in tens of billions of dollars and this amount is predicted to grow substantially over the next few years. Hence, it is important to know how buyers and sellers can influence their chances of success. Therefore, data were collected from eBay auctions for three different categories of collectible items, namely those with a published guide price, those with a rough guide price and those having no easily obtainable guide price. The options available to buyers and sellers of items were then analysed. It was found that it was hard for the seller to influence an item's achieved price significantly, apart from items with no guide price where the starting price could have an effect. Most bidders bid close to the current value and so there were insufficient data to determine the consequences of timing on the placing of high bids. For low bids, delaying a bid was found to improve significantly the chances of winning for one of the data sets. 相似文献