首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   531263篇
  免费   6467篇
  国内免费   1282篇
工业技术   539012篇
  2021年   3561篇
  2019年   3418篇
  2018年   12870篇
  2017年   13272篇
  2016年   9893篇
  2015年   4521篇
  2014年   7036篇
  2013年   21623篇
  2012年   13638篇
  2011年   22924篇
  2010年   19351篇
  2009年   20192篇
  2008年   20385篇
  2007年   22131篇
  2006年   13066篇
  2005年   15184篇
  2004年   13401篇
  2003年   12788篇
  2002年   11502篇
  2001年   11283篇
  2000年   10926篇
  1999年   11334篇
  1998年   26973篇
  1997年   19440篇
  1996年   15303篇
  1995年   11628篇
  1994年   10667篇
  1993年   10264篇
  1992年   7831篇
  1991年   7388篇
  1990年   7125篇
  1989年   7024篇
  1988年   6833篇
  1987年   5752篇
  1986年   5807篇
  1985年   6838篇
  1984年   6259篇
  1983年   5855篇
  1982年   5213篇
  1981年   5481篇
  1980年   5043篇
  1979年   5041篇
  1978年   4899篇
  1977年   5748篇
  1976年   7530篇
  1975年   4227篇
  1974年   4086篇
  1973年   4119篇
  1972年   3396篇
  1971年   3032篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
91.
92.
93.
Potential mGAT4 inhibitors derived from the lead substance (S)-SNAP-5114 have been synthesized and characterized for their inhibitory potency. Variations from the parent compound included the substitution of one of its aromatic 4-methoxy and 4-methoxyphenyl groups, respectively, with a more polar moiety, including a carboxylic acid, alcohol, nitrile, carboxamide, sulfonamide, aldehyde or ketone function, or amino acid partial structures. Furthermore, it was investigated how the substitution of more than one of the aromatic 4-methoxy groups affects the potency and selectivity of the resulting compounds. Among the synthesized test substances (S)-1-{2-[(4-formylphenyl)bis(4-methoxyphenyl)-methoxy]ethyl}piperidine-3-carboxylic acid, that features a carbaldehyde function in place of one of the aromatic 4-methoxy moieties of (S)-SNAP-5114, was found to have a pIC50 value of 5.89±0.07, hence constituting a slightly more potent mGAT4 inhibitor than the parent substance while showing comparable subtype selectivity.  相似文献   
94.
JOM - Alpha-radiation damage in metals is a concern for long-term radioactive storage and systems that produce nuclear energy. Accurate prediction of irradiated material properties and failure...  相似文献   
95.
96.
97.
98.
99.
100.
The work reported involved the fabrication of an electrospun tubular conduit of a gelatin and polycaprolactone (PCL) blend as an adventitia‐equivalent construct. Gelatin was included as the matrix for increased biocompatibility with the addition of PCL for durability. This is contrary to most of the literature available for biomaterials based on blends of gelatin and PCL where PCL is the major matrix. The work includes the assiduous selection of key electrospinning parameters to obtain smooth bead‐free fibres with a narrow distribution of pore size and fibre diameter. Few reports elucidate the optimization of all electrospinning parameters to fabricate tubular conduits with a focus on obtaining homogeneous pores and fibres. This stepwise investigation would be unique for the fabrication of gelatin–PCL electrospun tubular constructs. The fabricated microfibrous gelatin–PCL constructs had pores of size ca 50–100 μm reportedly conducive for cell infiltration. The measured value of surface roughness of 57.99 ± 17.4 nm is reported to be favourable for protein adhesion and cell adhesion. The elastic modulus was observed to be similar to that of the tunica adventitia of the native artery. Preliminary in vitro and in vivo biocompatibility tests suggest safe applicability as a biomaterial. Minimal cytotoxicity was observed using MTT assay. Subcutaneous implantation of the scaffold demonstrated acute inflammation which decreased by day 15. The findings of this study could enable the fabrication of smooth bead‐free microfibrous gelatin–PCL tubular construct as viable biomaterial which can be included in a bilayer or a trilayer scaffold for vascular tissue engineering. © 2019 Society of Chemical Industry  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号