全文获取类型
收费全文 | 3673篇 |
免费 | 105篇 |
国内免费 | 15篇 |
专业分类
化学 | 2253篇 |
晶体学 | 15篇 |
力学 | 196篇 |
数学 | 751篇 |
物理学 | 578篇 |
出版年
2023年 | 20篇 |
2022年 | 52篇 |
2021年 | 104篇 |
2020年 | 75篇 |
2019年 | 52篇 |
2018年 | 66篇 |
2017年 | 59篇 |
2016年 | 117篇 |
2015年 | 106篇 |
2014年 | 83篇 |
2013年 | 192篇 |
2012年 | 213篇 |
2011年 | 259篇 |
2010年 | 149篇 |
2009年 | 126篇 |
2008年 | 212篇 |
2007年 | 230篇 |
2006年 | 169篇 |
2005年 | 161篇 |
2004年 | 147篇 |
2003年 | 126篇 |
2002年 | 101篇 |
2001年 | 45篇 |
2000年 | 28篇 |
1999年 | 40篇 |
1998年 | 37篇 |
1997年 | 37篇 |
1996年 | 38篇 |
1995年 | 31篇 |
1994年 | 31篇 |
1993年 | 48篇 |
1992年 | 23篇 |
1991年 | 28篇 |
1990年 | 29篇 |
1989年 | 21篇 |
1988年 | 28篇 |
1987年 | 22篇 |
1986年 | 24篇 |
1985年 | 46篇 |
1984年 | 41篇 |
1983年 | 23篇 |
1982年 | 27篇 |
1981年 | 32篇 |
1980年 | 26篇 |
1979年 | 22篇 |
1978年 | 26篇 |
1977年 | 23篇 |
1976年 | 23篇 |
1975年 | 13篇 |
1974年 | 23篇 |
排序方式: 共有3793条查询结果,搜索用时 15 毫秒
101.
The renewal of the urban waterfronts has become a major focus of attention for politicians and decision makers in the city’s management programs. The recognition of the patterns that define the waterfronts’ identity is essential to select new strategies of intervention for the environmental recovery. In order to create adequate environments for everyday life within a sustainable development, new links between human senses, human perception and design need to be created. Within this wide approach, the landscape and the soundscape play a significant role and can become a key driving force in the implementation of the changes. New techniques have to be tested to identify the sonic and visual parameters capable to explain the specificity of a waterfront. With this purpose, an artificial neural network (ANN) was developed, and the relative importance of the input variables was evaluated. The collected database was also analysed by multiple linear regression (MLR) to compare the outcomes of both models. The urban waterfront of Naples (Italy) was chosen as case study. The results obtained show that the performance of the neural network is better than the one of the linear regression (rANN = 0.949, rMLR = 0.639). The interpretation of the relative importance method is also quite satisfactory in the ANN. 相似文献
102.
Gabriella Ieronimo Alessandro Mondelli Francesco Tibiletti Angelo Maspero Giovanni Palmisano Simona Galli Stefano Tollari Norberto Masciocchi Kenneth M. Nicholas Silvia Tagliapietra Giancarlo Cravotto Andrea Penoni 《Tetrahedron》2013
The thermal reaction between nitrosoarenes and alkynes under alkylating conditions produces N-alkoxyindoles as the major products in moderate to good yields and excellent regioselectivity. Various electrophiles are used affording different N–O-protected hydroxyindoles in a multi-component fashion. Privileged acetylenic substrates used in reactions with substituted nitrosoarenes are arylalkynes or propiolates. Potentially bioactive compounds and other classes of highly functionalizable indole products were prepared. Reactions between o-carbomethoxy-nitrosoarenes and arylacetylenes provided tricyclic compounds containing an acylaziridine indoline skeleton. 相似文献
103.
104.
105.
106.
107.
108.
Stacey M. Frumm Zi Peng Fan Kenneth N. Ross Jeremy R. Duvall Supriya Gupta Lynn VerPlank Byung-Chul Suh Edward Holson Florence F. Wagner William B. Smith Ronald M. Paranal Christopher F. Bassil Jun Qi Giovanni Roti Andrew L. Kung James E. Bradner Nicola Tolliday Kimberly Stegmaier 《Chemistry & biology》2013,20(5):713-725
109.
The synthesis of the methyl esters of optically pure trans and cis 4-guanidinocyclohexylglycine as rigid analogues of D-arginine methyl ester are described. 相似文献