全文获取类型
收费全文 | 1207篇 |
免费 | 271篇 |
国内免费 | 189篇 |
专业分类
化学 | 691篇 |
晶体学 | 83篇 |
力学 | 92篇 |
综合类 | 26篇 |
数学 | 310篇 |
物理学 | 465篇 |
出版年
2023年 | 9篇 |
2022年 | 40篇 |
2021年 | 29篇 |
2020年 | 35篇 |
2019年 | 30篇 |
2018年 | 29篇 |
2017年 | 54篇 |
2016年 | 36篇 |
2015年 | 64篇 |
2014年 | 85篇 |
2013年 | 112篇 |
2012年 | 141篇 |
2011年 | 173篇 |
2010年 | 137篇 |
2009年 | 123篇 |
2008年 | 103篇 |
2007年 | 87篇 |
2006年 | 40篇 |
2005年 | 35篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 17篇 |
1999年 | 18篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 13篇 |
1990年 | 5篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 14篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 8篇 |
1966年 | 3篇 |
排序方式: 共有1667条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
采用浮床黑麦草(Lolium multi florum)对畜禽养殖富营养水体氨氮的净化效应及动态过程进行了研究.结果表明:浮床黑麦草对富营养水体中的氨氮具有明显的净化效果.当覆盖率30%时,对氨氮的去除率最高可达到95.89%.对其去除水体氨氮的动态过程拟合表明符合三次方程曲线.该研究为冬季陆生植物修复富营养水体提供重要依据. 相似文献
5.
John T. Buchanan 《The Journal of the Operational Research Society》1994,45(9):1050-1059
Increasingly, it is becoming recognized that interactive solution methods should provide not only a solution to a multiple criteria decision making (MCDM) problem, but also the opportunity for decision makers to learn about their own preferences. In this paper, we describe an experiment that examines three MCDM solution methods and the process of converging on a final solution. Twenty-four management students participated in the experiment and were required to solve two completely different MCDM problems. Within this experimental framework, we examined the use of a two-stage approach to decision making. Both quantitative and qualitative results are presented. Preferences among the different solution methods vary significantly. Several conclusions are drawn concerning the desirable features of interactive MCDM solution methods. 相似文献
6.
We report a new approach for the self-assembly of cuboid micro-parts onto Si substrates to construct three-dimensional microstructures. To perform assembly, the Si substrates are prepared with a deep cavity array as binding sites. An aggregate composed of hundreds of uniformly aligned micro-parts is formed at the C10F18-H2O interface. The micro-parts are arranged by passing the substrate through the aggregate of micro-parts, thus the micro-parts are left on the substrate, and then the substrate is vibrated ultrasonically in the solution, making it possible for the micro-parts to fall into the cavities on the substrate. Finally the substrate is pulled out of the solution after assembly. This technique could give a high yield of up to 70%, providing a new method for micro-assembly. 相似文献
7.
Effect of Molecular Weight on Liquid Crystal Photoalignment by Photosensitive Polyester Containing Thrifluoromethyl Moieties
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We investigate the liquid-crystal (LC) alignment direction on photoalignment films formed from photosensitive polyester containing thrifluoromethyl moieties (PPDA) with various molecular weights by crossed polarized optical microscopy. It is found that LC alignment behaviour changes with molecular weight of PPDA. The LC alignment on PPDA irradiated films with the highest molecular weight is homogeneous, while those with low and intermediate molecular weights are homeotropic. However, surface morphologies show weak dependence on molecular weight. The surfaces are smooth and there is no clear morphological anisotropy on these aligned films observed by an atomic force microscope. The surface energies of the irradiated films are also measured by using an indirect contact-angle method where both surface energy and its polar component, increase with increasing molecular weight. Different polar surface energies can be considered as a main reason for different alignment characteristics. 相似文献
8.
Bonner BE Buchanan JA Clement JM Corcoran MD Krishna NM Kruk JW Miettinen HE Moss RM Mutchler GS Nessi-Tedaldi F Nessi M Phillips GC Roberts JB Stevenson PM Tonse SR Birman A Chung SU Etkin A Fernow RC Kirk H Protopopescu SD Willutzki H Hallman T Madansky L Bar-Yam Z Dowd J Kern W King E Mayes BW Pinsky LS 《Physical review D: Particles and fields》1990,41(1):13-16
9.
Bonner BE Buchanan JA Clement JM Corcoran MD Krishna NM Kruk JW Lincoln DW Miettinen HE Mutchler GS Nessi-Tedaldi F Nessi M Phillips GC Roberts JB Stevenson PM Tonse SR White JL Chung SU Etkin A Fernow RC Protopopescu SD Willutzki H Hallman T Madansky L Pinsky LS 《Physical review letters》1989,62(14):1591-1594
10.
Aihara H Alston-Garnjost M Avery RE Barbaro-Galtieri A Barker AR Barnes AV Barnett BA Bauer DA Bengtsson H Bintinger DL Bobbink GJ Bolognese TS Bross AD Buchanan CD Buijs A Cain MP Caldwell DO Clark AR Cowan GD Crane DA Dahl OI Derby KA Eastman JJ Eberhard PH Eisner AM Enomoto R Erné FC Fujii T Gary JW Gorn W Hauptman JM Hofmann W Huth JE Hylen J Kamae T Kaye HS Kees KH Kenney RW Kerth LT Ko W Koda RI Kofler RR Kwong KK Lander RL Langeveld WG Layter JG Linde FL Lindsey CS Loken SC Lu A Lu X 《Physical review letters》1986,57(8):945-948