全文获取类型
收费全文 | 1513篇 |
免费 | 15篇 |
国内免费 | 2篇 |
专业分类
化学 | 818篇 |
晶体学 | 9篇 |
力学 | 52篇 |
数学 | 139篇 |
物理学 | 397篇 |
综合类 | 115篇 |
出版年
2021年 | 12篇 |
2019年 | 12篇 |
2016年 | 10篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 51篇 |
2012年 | 57篇 |
2011年 | 78篇 |
2010年 | 42篇 |
2009年 | 52篇 |
2008年 | 73篇 |
2007年 | 80篇 |
2006年 | 68篇 |
2005年 | 69篇 |
2004年 | 57篇 |
2003年 | 52篇 |
2002年 | 39篇 |
2001年 | 36篇 |
2000年 | 35篇 |
1999年 | 23篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 33篇 |
1995年 | 34篇 |
1994年 | 33篇 |
1993年 | 28篇 |
1992年 | 28篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 21篇 |
1988年 | 18篇 |
1987年 | 17篇 |
1986年 | 31篇 |
1985年 | 13篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1981年 | 21篇 |
1980年 | 15篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1977年 | 19篇 |
1976年 | 12篇 |
1975年 | 22篇 |
1974年 | 15篇 |
1973年 | 16篇 |
1972年 | 10篇 |
1971年 | 14篇 |
1970年 | 10篇 |
1969年 | 10篇 |
1968年 | 10篇 |
排序方式: 共有1530条查询结果,搜索用时 7 毫秒
1.
There are essentially two schools of thought regarding the function of decision support systems. One is that the main purpose is to support the decision-maker in whatever style of decision-making he or she wishes. The other is that the support, while suiting the decision-maker's individual style, must also be based on an appropriate theoretical paradigm. The work with students of decision support systems reported here suggests that the latter, normative, view is not one which comes naturally to many of the students, even when working on an example where it seemed relatively easy to incorporate. Other conclusions are also presented, relating to the choice of software for decision support system development, the process of teaching about decision support systems, and group formation. 相似文献
2.
Alex Edwards 《The Journal of the Operational Research Society》1994,45(12):1467-1467
3.
The use of a direct liquid introduction type liquid chromatographic-mass spectrometric interface to study highly thermally labile rifamycin antibiotics is described. Using negative ionization, abundant molecular ions were observed, and the spectra, also contained structurally significant fragments. Variation of the high-performance liquid chromatographic parameters did not change the spectra, thus making it easy to change chromatographic conditions. In quantitative studies, a surprising correlation was found, indicating that the mass spectrometric signal was proportional to the square of the sample concentration. 相似文献
4.
5.
G. Halambalakis N. Rousseau O. Briot S. Ruffenach R.L. Aulombard P.R. Edwards K.P. ODonnell T. Wojtowicz P. Ruterana 《Superlattices and Microstructures》2004,36(4-6):721
We have studied the optical properties of Eu doped GaN thin films. We have grown high quality Eu doped GaN thin films by using Gas Source Molecular Beam Epitaxy (GSMBE), with 1.4% Eu concentration. The Full Width at Half Maximum (FWHM) of the X-ray diffraction in an omega scan was found to be 288 arcsecs. Low Eu concentration (0.08%) doped GaN thin films were grown, where Eu-related photoluminescence at 622 and 613 nm was detected using above band-gap excitation at 2 K. For high Eu concentration of 30% GaN:Eu crystal photoluminescence (PL) and cathodoluminescence (CL) spectra show strong and intense transitions at 622 and 664 nm, but also at 593 nm for CL spectra, with a similar transition observed from the low Eu concentration sample. 相似文献
6.
A proper edge colouring of a graph G is neighbour-distinguishing provided that it distinguishes adjacent vertices by sets of colours of their incident edges.
It is proved that for any planar bipartite graph G with Δ(G)≥12 there is a neighbour-distinguishing edge colouring of G using at most Δ(G)+1 colours. Colourings distinguishing pairs of vertices that satisfy other requirements are also considered. 相似文献
7.
8.
9.
10.