全文获取类型
收费全文 | 1767篇 |
免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 84篇 |
金属工艺 | 3篇 |
机械仪表 | 5篇 |
建筑科学 | 7篇 |
矿业工程 | 8篇 |
轻工业 | 8篇 |
石油天然气 | 9篇 |
无线电 | 46篇 |
一般工业技术 | 48篇 |
冶金工业 | 1534篇 |
原子能技术 | 7篇 |
自动化技术 | 6篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 6篇 |
2012年 | 9篇 |
2011年 | 13篇 |
2010年 | 8篇 |
2009年 | 11篇 |
2008年 | 7篇 |
2007年 | 11篇 |
2006年 | 7篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 31篇 |
1998年 | 449篇 |
1997年 | 260篇 |
1996年 | 182篇 |
1995年 | 147篇 |
1994年 | 89篇 |
1993年 | 82篇 |
1992年 | 19篇 |
1991年 | 18篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 17篇 |
1980年 | 24篇 |
1979年 | 4篇 |
1978年 | 11篇 |
1977年 | 57篇 |
1976年 | 105篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1969年 | 4篇 |
排序方式: 共有1768条查询结果,搜索用时 15 毫秒
81.
82.
U8 small nucleolar RNA (snoRNA) is essential for metazoan ribosomal RNA (rRNA) processing in nucleoli. The sequences and structural features in Xenopus U8 snoRNA that are required for its nucleolar localization were analyzed. Fluorescein-labeled U8 snoRNA was injected into Xenopus oocyte nuclei, and fluorescence microscopy of nucleolar preparations revealed that wild-type Xenopus U8 snoRNA localized to nucleoli, regardless of the presence or nature of the 5' cap on the injected U8 snoRNA. Nucleolar localization was observed when loops or stems in the 5' portion of U8 that are critical for U8 snoRNA function in rRNA processing were mutated. Therefore, sites of interaction in U8 snoRNA that potentially tether it to pre-rRNA are not essential for nucleolar localization of U8. Boxes C and D are known to be nucleolar localization elements (NoLEs) for U8 snoRNA and other snoRNAs of the Box C/D family. However, the spatial relationship of Box C to Box D was not crucial for U8 nucleolar localization, as demonstrated here by deletion of sequences in the two stems that separate them. These U8 mutants can localize to nucleoli and function in rRNA processing as well. The single-stranded Cup region in U8, adjacent to evolutionarily conserved Box C, functions as a NoLE in addition to Boxes C and D. Cup is unique to U8 snoRNA and may help bind putative protein(s) needed for nucleolar localization. Alternatively, Cup may help to retain U8 snoRNA within the nucleolus. 相似文献
83.
A hypothesis on autoregulatory mechanism of reproduction of bone matrix structural changes was proposed resulting from the theoretical study based on author's own data and data documented in literature. This mechanism seems to underly osteoporosis development. All etiological factors of osteoporosis reported were united into a common pathogenetic mechanism on the basis of this conception. 相似文献
84.
In mice hetero- and homozygotic in relation to the diabetic gene db, it was shown that the regulation of the pancreatic endocrine function by hypothalamus is mediated at least by two mechanisms: neurohumoral one connected with hormone secretion by paraventricular and supraoptical nuclei and by a neuroconductivity mechanism connected with the ventromedial nucleus and lateral hypothalamic area. 相似文献
85.
86.
87.
88.
BR Babu SJ Zhu AV Ramayya JH Hamilton LK Peker MG Wang TN Ginter J Kormicki WC Ma JD Cole R Aryaeinejad K Butler-Moore YX Dardenne MW Drigert GM Ter-Akopian YT Oganessian JO Rasmussen S Asztalos IY Lee AO Macchiavelli SY Chu KE Gregorich MF Mohar S Prussin MA Stoyer RW Lougheed KJ Moody JF Wild 《Canadian Metallurgical Quarterly》1996,54(2):568-571
89.
AV Sivachev 《Canadian Metallurgical Quarterly》1994,(4):28-31
It has been experimentally found that larval and pulmonary paragonimiasis types are caused by the trematode Paragonimus westermani ichunensis. The development of either paragonimiasis in nontypical definitive hosts depends on the stage of larval development when they penetrate into the mammal. Only the P. westermani ichunensis trematode is likely to develop with the participation of Juga mollusks on the territory of the Primorye. 相似文献
90.