全文获取类型
收费全文 | 2962篇 |
免费 | 73篇 |
国内免费 | 23篇 |
专业分类
化学 | 2117篇 |
晶体学 | 30篇 |
力学 | 26篇 |
数学 | 253篇 |
物理学 | 632篇 |
出版年
2023年 | 19篇 |
2021年 | 23篇 |
2020年 | 33篇 |
2019年 | 32篇 |
2018年 | 29篇 |
2017年 | 14篇 |
2016年 | 35篇 |
2015年 | 52篇 |
2014年 | 77篇 |
2013年 | 149篇 |
2012年 | 142篇 |
2011年 | 166篇 |
2010年 | 85篇 |
2009年 | 106篇 |
2008年 | 152篇 |
2007年 | 173篇 |
2006年 | 162篇 |
2005年 | 169篇 |
2004年 | 143篇 |
2003年 | 141篇 |
2002年 | 141篇 |
2001年 | 71篇 |
2000年 | 50篇 |
1999年 | 38篇 |
1998年 | 30篇 |
1997年 | 35篇 |
1996年 | 40篇 |
1995年 | 20篇 |
1994年 | 26篇 |
1993年 | 32篇 |
1992年 | 43篇 |
1991年 | 32篇 |
1990年 | 42篇 |
1989年 | 25篇 |
1988年 | 38篇 |
1987年 | 40篇 |
1986年 | 37篇 |
1985年 | 44篇 |
1984年 | 40篇 |
1983年 | 23篇 |
1982年 | 31篇 |
1981年 | 25篇 |
1980年 | 31篇 |
1979年 | 38篇 |
1978年 | 18篇 |
1977年 | 19篇 |
1975年 | 17篇 |
1974年 | 42篇 |
1973年 | 17篇 |
1972年 | 11篇 |
排序方式: 共有3058条查询结果,搜索用时 320 毫秒
81.
Hirozumi Fujii 《Proceedings of the American Mathematical Society》1996,124(9):2923-2933
It is well-known that any Laurent polynomial satisfying and is the Alexander polynomial of a knot in . We show that can be realized by a knot which has the following properties simultaneously: (i) tunnel number 1; (ii) bridge index 3; and (iii) unknotting number 1.
82.
Mamoru Sato Yukiteru Katsube Masaaki Katai Jun' ichi Katakawa Tadahiro Tetsumi 《Journal of chemical crystallography》1996,26(2):153-156
The crystal and molecular structure of a grayanotoxin III derivative, 6-0-acetylgrayanotoxin III is presented. The crystal is orthorhombic, space group P212121, witha=15.582(3),b=21.304(3),c=6.339(3)Å,V=2104(1) Å3
Z=4. The structure was solved by direct methods and refined by full matrix least-squares methods to a finalR=0.047 for 1763 independent reflections withF
0>3 (F
0) The molecule is based on a tetracyclic structure consisting of two five-membered, one six-membered, and one seven-membered ring with various conformations. 相似文献
83.
84.
85.
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
86.
Several beta-secretase inhibitors were designed based on hydroxyethylamine dipeptide isostere (HDI) structures and were synthesized by a methodology using the aza-Payne rearragement and O,N-acyl transfer reactions to study their structure-activity relationships. Among these pseudopeptides, effective compounds were developed as the first beta-secretase inhibitors containing the HDI transition state mimic with potent enzyme inhibitory activity (IC50 < 100 nM). 相似文献
87.
Carbazoledioxazines with an angular type structure (5,15-dialkyl-7,17-dialkyloxy-9,19-dichloro-5,15-dihydrodiindolo[2,3-c:2′,3′-n]triphenodioxazines) were selectively synthesized by electrochemical oxidative ring closure of precursors (2,5-bis(9-alkyl-2-alkyloxy-3-carbazolylamino)-3,6-dichloro-1,4-benzoquinones). The structure was confirmed by 1H-nmr and other instrumental analyses. Their thermal properties and solubilities were investigated and were compared with those of carbazoledioxazines with a linear type structure. 相似文献
88.
The common synthetic intermediate of a potent and promising anticancer agent, fostriecin, was synthesized using a unique method that combines four catalytic asymmetric reactions as shown above. 相似文献
89.
90.
Aihara H Alston-Garnjost M Bakken JA Barbaro-Galtieri A Barnes AV Barnett BA Bengtsson H Blumenfeld BJ Bross AD Buchanan CD Chamberlain O Chien C Clark AR Cordier A Dahl OI Day CT Derby KA Eberhard PH Fancher DL Fujii H Fujii T Gabioud B Gary JW Gorn W Hadley NJ Hauptman JM Hofmann W Huth JE Hylen J Kamae T Kaye HS Kenney RW Kerth LT Koda RI Kofler RR Kwong KK Layter JG Lindsey CS Loken SC Lu X Lynch GR Madansky L Madaras RJ Maruyama K Marx JN Matthews JA Melnikoff SO Moses W Nemethy P 《Physical review letters》1985,54(4):270-273