全文获取类型
收费全文 | 4578篇 |
免费 | 147篇 |
国内免费 | 26篇 |
专业分类
化学 | 3394篇 |
晶体学 | 49篇 |
力学 | 62篇 |
数学 | 319篇 |
物理学 | 927篇 |
出版年
2022年 | 33篇 |
2021年 | 43篇 |
2020年 | 56篇 |
2019年 | 65篇 |
2018年 | 49篇 |
2017年 | 45篇 |
2016年 | 102篇 |
2015年 | 70篇 |
2014年 | 106篇 |
2013年 | 235篇 |
2012年 | 236篇 |
2011年 | 272篇 |
2010年 | 150篇 |
2009年 | 144篇 |
2008年 | 268篇 |
2007年 | 257篇 |
2006年 | 257篇 |
2005年 | 237篇 |
2004年 | 193篇 |
2003年 | 181篇 |
2002年 | 164篇 |
2001年 | 99篇 |
2000年 | 86篇 |
1999年 | 80篇 |
1998年 | 50篇 |
1997年 | 56篇 |
1996年 | 45篇 |
1995年 | 45篇 |
1994年 | 46篇 |
1993年 | 52篇 |
1992年 | 71篇 |
1991年 | 71篇 |
1990年 | 43篇 |
1989年 | 44篇 |
1988年 | 47篇 |
1987年 | 40篇 |
1986年 | 44篇 |
1985年 | 71篇 |
1984年 | 63篇 |
1983年 | 45篇 |
1982年 | 51篇 |
1981年 | 37篇 |
1980年 | 36篇 |
1979年 | 39篇 |
1978年 | 28篇 |
1977年 | 29篇 |
1976年 | 39篇 |
1975年 | 26篇 |
1974年 | 27篇 |
1973年 | 30篇 |
排序方式: 共有4751条查询结果,搜索用时 15 毫秒
111.
Akira Saito 《Combinatorica》1996,16(3):433-437
A graphG is said to bek-path-connected if every pair of distinct vertices inG are joined by a path of length at leastk. We prove that if max{deg
G
x
, deg
G
y
}k for every pair of verticesx,y withd
G
(x,y)=2 in a 2-connected graphG, whered
G
(x,y) is the distance betweenx andy inG, thenG isk-path-connected. 相似文献
112.
Takayuki Furuta 《Proceedings of the American Mathematical Society》1996,124(10):3071-3075
We shall introduce a generalized Aluthge transformation on -
hyponormal operators and also, by using the Furuta inequality, we shall give several properties on this generalized Aluthge transformation as further extensions of some results of Aluthge.
hyponormal operators and also, by using the Furuta inequality, we shall give several properties on this generalized Aluthge transformation as further extensions of some results of Aluthge.
113.
Ishikawa T Watanabe T Tanigawa H Saito T Kotake KI Ohashi Y Ishii H 《The Journal of organic chemistry》1996,61(8):2774-2779
Nitrosation of 3-methoxyphenol and 1-naphthol were examined under both acidic (NaNO(2)-EtCO(2)H-H(2)O) and basic (i-AmNO(2)-K(2)CO(3)-DMF) conditions. Acidic nitrosations afforded ortho-directed products, whereas para-directed nitrosations were observed under basic conditions to yield p-quinone monooximes. The basic para-directed nitrosation was further examined using 15 phenols, two naphthols, and four phenolic heterocyclics. A one-pot operation of the basic nitrosation followed by methylation with dimethyl sulfate gave the corresponding methyl ethers in high yield. Two p-quinone monooximes derived from 3-methoxyphenol and 8-hydroxyquinoline showed a moderate activity against HSV-1, and the latter oxime was also effective against HSV-2. On the other hand, p-quinone monooximes derived from methyl salicylate, 1-naphthol, 7-hydroxy-2-methylbenzo[b]furan, and 8-hydroxycoumarin showed the comparable activity to that of DDI against HIV-1. 相似文献
114.
115.
116.
117.
118.
Allen WH Bond IA Budding E Conway MJ Daniel A Fenton KB Fujii H Fujii Z Hayashida N Hibino K Honda M Humble JE Kabe S Kasahara K Kifune T Lythe GD Masaike A Matsubara Y Mitsui K Miura Y Mori M Muraki Y Nagano M Nakamura T Nishizawa M Morris PM Ogio S Saito T Sakata M Sato H Shimizu HM Spencer M Storey JR Tanimori T Teshima M Torii S Wadsworth A Watase Y Woodhams MD Yamamoto Y Yock PC Yuda T 《Physical review D: Particles and fields》1993,48(2):466-478
119.
Akchurin N Langland J Onel Y Bonner BE Corcoran MD Cranshaw J Nessi-Tedaldi F Nessi M Nguyen C Roberts JB Skeens J White JL Bravar A Giacomich R Penzo A Schiavon P Zanetti A Bystricky J Lehar F de Lesquen A van Rossum L Cossairt JD Read AL Derevschikov AA Matulenko YA Meschanin AP Nurushev SB Patalakha DI Rykov VL Solovyanov VL Vasiliev AN Grosnick DP Hill DA Laghai M Lopiano D Ohashi Y Shima T Spinka H Stanek RW Underwood DG Yokosawa A Funahashi H Goto Y Imai K Itow Y Makino S Masaike A 《Physical review D: Particles and fields》1993,48(7):3026-3036
120.
Rieko Matsuda Yuzuru Hayashi Takashi Suzuki Yukio Saito 《Fresenius' Journal of Analytical Chemistry》1993,347(6-7):225-229
Summary The influences of decreasing column diameter and length on two analytical goals, the precision and solvent efficiency, in reversed-phase liquid-chromatography are studied. Low solvent consumption is one of analytical advantages of miniaturized columns and is shown to be quantitatively evaluated by the precision and solvent efficiency which are defined to be the total Shannon mutual information obtained from an assay and the information obtained in a unit solvent volume, respectively. Analysis of paraben food additives on a microbore column is taken as an example. In trace analysis, the relative standard deviation (RSD) of measurements theoretically derived from the precision is shown to approach to the observed ones. 相似文献