全文获取类型
收费全文 | 1662篇 |
免费 | 6篇 |
专业分类
综合类 | 1篇 |
化学工业 | 14篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
建筑科学 | 1篇 |
能源动力 | 4篇 |
轻工业 | 13篇 |
石油天然气 | 1篇 |
无线电 | 3篇 |
一般工业技术 | 18篇 |
冶金工业 | 1600篇 |
原子能技术 | 1篇 |
自动化技术 | 8篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2013年 | 7篇 |
2012年 | 2篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 2篇 |
1999年 | 43篇 |
1998年 | 462篇 |
1997年 | 272篇 |
1996年 | 172篇 |
1995年 | 109篇 |
1994年 | 101篇 |
1993年 | 103篇 |
1992年 | 12篇 |
1991年 | 26篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 27篇 |
1986年 | 16篇 |
1985年 | 23篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 15篇 |
1980年 | 17篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 43篇 |
1976年 | 106篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1965年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1668条查询结果,搜索用时 0 毫秒
91.
92.
M Jeltsch A Kaipainen V Joukov X Meng M Lakso H Rauvala M Swartz D Fukumura RK Jain K Alitalo 《Canadian Metallurgical Quarterly》1997,276(5317):1423-1425
No growth factors specific for the lymphatic vascular system have yet been described. Vascular endothelial growth factor (VEGF) regulates vascular permeability and angiogenesis, but does not promote lymphangiogenesis. Overexpression of VEGF-C, a ligand of the VEGF receptors VEGFR-3 and VEGFR-2, in the skin of transgenic mice resulted in lymphatic, but not vascular, endothelial proliferation and vessel enlargement. Thus, VEGF-C induces selective hyperplasia of the lymphatic vasculature, which is involved in the draining of interstitial fluid and in immune function, inflammation, and tumor metastasis. VEGF-C may play a role in disorders involving the lymphatic system and may be of potential use in therapeutic lymphangiogenesis. 相似文献
93.
94.
95.
96.
97.
98.
In vitro experiments that characterize DNA-protein interactions by artificial selection, such as SELEX,are often performed with the assumption that the experimental conditions are equivalent to natural ones. To test whether SELEX gives natural results, we compared sequence logos composed from naturally occurring leucine-responsive regulatory protein (Lrp) binding sites with those composed from SELEX-generated binding sites. The sequence logos were significantly different, indicating that the binding conditions are disparate. A likely explanation is that the SELEX experiment selected for a dimeric or trimeric Lrp complex bound to DNA. In contrast, natural sites appear to be bound by a monomer. This discrepancy suggests that in vitro selections do not necessarily give binding site sets comparable with the natural binding sites. 相似文献
99.
100.
CD Wu RS Wickert JE Williamson NC Sun RK Brynes WC Chan 《Canadian Metallurgical Quarterly》1999,111(1):105-110
The AGT1 permease is a alpha-glucoside-H+ symporter responsible for the active transport of maltose, trehalose, maltotriose, alpha-methylglucoside, melezitose and sucrose. In wild-type as well as in MAL constitutive strains, alpha-methylglucoside seemed to be the best inducer of transport activity, while trehalose had no inducing effect. Based on the initial rates of transport it seems that the sugar preferentially transported by this permease is trehalose, followed by sucrose. 相似文献