全文获取类型
收费全文 | 52633篇 |
免费 | 10008篇 |
国内免费 | 11637篇 |
专业分类
化学 | 38502篇 |
晶体学 | 1260篇 |
力学 | 3617篇 |
综合类 | 1236篇 |
数学 | 6589篇 |
物理学 | 23074篇 |
出版年
2024年 | 160篇 |
2023年 | 827篇 |
2022年 | 1892篇 |
2021年 | 1945篇 |
2020年 | 2034篇 |
2019年 | 2055篇 |
2018年 | 1836篇 |
2017年 | 2214篇 |
2016年 | 2353篇 |
2015年 | 2740篇 |
2014年 | 3352篇 |
2013年 | 4206篇 |
2012年 | 4687篇 |
2011年 | 4843篇 |
2010年 | 3980篇 |
2009年 | 4064篇 |
2008年 | 4515篇 |
2007年 | 3819篇 |
2006年 | 3715篇 |
2005年 | 3097篇 |
2004年 | 2338篇 |
2003年 | 1822篇 |
2002年 | 1832篇 |
2001年 | 1716篇 |
2000年 | 1538篇 |
1999年 | 1092篇 |
1998年 | 722篇 |
1997年 | 615篇 |
1996年 | 588篇 |
1995年 | 455篇 |
1994年 | 475篇 |
1993年 | 383篇 |
1992年 | 359篇 |
1991年 | 262篇 |
1990年 | 268篇 |
1989年 | 195篇 |
1988年 | 188篇 |
1987年 | 190篇 |
1986年 | 153篇 |
1985年 | 112篇 |
1984年 | 102篇 |
1983年 | 96篇 |
1982年 | 66篇 |
1981年 | 61篇 |
1980年 | 41篇 |
1979年 | 54篇 |
1978年 | 24篇 |
1977年 | 21篇 |
1965年 | 13篇 |
1964年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
A graph G is 3‐domination critical if its domination number γ is 3 and the addition of any edge decreases γ by 1. Let G be a 3‐connected 3‐domination critical graph of order n. In this paper, we show that there is a path of length at least n?2 between any two distinct vertices in G and the lower bound is sharp. © 2002 John Wiley & Sons, Inc. J Graph Theory 39: 76–85, 2002 相似文献
95.
Films of polytetrafluoroethylene (PTFE) were exposed to sodium naphthalenide (Na/naphtha) etchant so as to defluorinate the surface for obtaining hydroxyl functionality. Surface-initiators were immobilized on the PTFE films by esterification of 4,4′-azobis(4-cyanopentanoic acid) (ACP) and the hydroxyl groups covalently linked to the surface. Grafting of polymer brushes on the PTFE films was carried out by the surface-initiated free radical polymerization. Homopolymers brushes of methyl methacrylate (MMA) were prepared by free radical polymerization from the azo-functionalized PTFE surface. The chemical composition and topography of the graft-functionalized PTFE surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance (ATR) FT-IR spectroscopy and atomic force microscopy (AFM). Water contact angles on PTFE films were reduced by surface grafting of MMA. 相似文献
96.
Dierk Knittel Qinxue Wei Eckhard Schollmeyer 《Fresenius' Journal of Analytical Chemistry》1994,348(12):820-824
Different strategies are presented for the development of a voltammetric sensor for in-line measurement and monitoring of H2O2 in high concentrations (up to 30 g/l) as used in textile bleaching systems. When using macroelectrodes, signal saturation is observed even at medium concentrations. Some improvement can be achieved by hydrodynamic electrodes like ring-disk electrodes. Satisfactory results up to the desired level in practical solutions (possessing only limited conductivity) are obtained with Pt-microelectrodes. 相似文献
97.
98.
Wei Guoqiang 《数学年刊B辑(英文版)》1998,19(4):465-472
1.IntroductionInwhatfollows,allofHilbertspacesappearedinthispaperareinfinite-dimensionalseparablecomplexHilbertspace.IfHisaHilbertspace,thenC(n)denotestheC*--algebraofallboundedlinearoperatorsonHandK(H)denotesthesetofcompactoperatorsonn.TwooperatorsSandTarecalledapproximatelyequivalentifthereisasequenc{Un}ofunitaryoperatorssuchthatlIU:SUn--Tll-0(n-- co).SimilarlytwooperatosSandTareapproximatelysimilarifthereisasequence{Vn}ofinvertibleoperatorswithsup(llVn11,11VJ'11)相似文献
99.
分形维数与城市规模分布评析 总被引:3,自引:1,他引:2
本在分形概念的基础上,指出城市规模分布是基于统计意义上的一种分形分布,并计算了安徽省1978~1998年城市规模分布的分维值,评析了安徽省城市规模分布变化的特征。 相似文献
100.
Wei Zhou Ruonong Fu Rongji Dai Zaifu Huang Yanfei Chen 《Journal of separation science》1994,17(10):719-722
A new kind of side chain liquid crystalline polysiloxane containing a crown ether with a longer spacer (PSC-11) has been prepared and coated on a fused silica capillary column. The main chroma-tographic characteristics including efficiency, polarity, and selectivity have been examined. The phase exhibits the retention properties of both liquid crystal and crown ether stationary phases and possesses higher efficiency and better selectivity than PSC-3, which has a shorter spacer between the main polysiloxane chain and liquid crystalline side chain. 相似文献