全文获取类型
收费全文 | 139篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
156篇 |
出版年
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 5篇 |
2011年 | 10篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1971年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有156条查询结果,搜索用时 15 毫秒
151.
152.
Developing taste buds in the anterior mandibular floor of perihatching
chicks were studied by high voltage electron microscopic autoradiography in
order to identify proliferating gemmal cell types. Montaged profiles of 29
taste buds in five cases euthanized between embryonic day 21 and
posthatching day 2 were analyzed after a single [3H]thymidine injection
administered on embryonic day 16, 17 or 18. Results showed that dark cells
comprised 55% of identified (n = 900 cells) and 62% of labeled (n = 568
cells) gemmal cells as compared with light, intermediate, basal or
perigemmal bud cells. Dark cells had both a greater (P < 0.05) number of
labeled cells and a greater amount of label (grains/nucleus) than the other
four bud cell types, irrespective of injection day. The nuclear area
(micron 2) of dark cells was not significantly larger (P > 0.05) than
that of the other gemmal cell types and therefore cannot account for the
greater amount for label in the dark cells. Interestingly, only dark cells
showed a positive correlation (P < 0.003) between amount of label and
nuclear area. Results suggest that, during the perihatching period of
robust cell proliferation, dividing dark cells may give rise primarily, but
not exclusively, to dark cell progeny.
相似文献
153.
154.
155.
Yari Carlomagno Sireesha Manne Michael DeTure Mercedes Prudencio Yong-Jie Zhang Rana Hanna Al-Shaikh Judith A. Dunmore Lillian M. Daughrity Yuping Song Monica Castanedes-Casey Laura J. Lewis-Tuffin Katharine A. Nicholson Zbigniew K. Wszolek Dennis W. Dickson Anthony W.P. Fitzpatrick Leonard Petrucelli Casey N. Cook 《Cell reports》2021,34(11):108843
156.
Lorenzo Chiariotti Pietro Alifano M. Stella Carlomagno Carmelo B. Bruni 《Molecular & general genetics : MGG》1986,203(3):382-388
Summary In this paper we report the nucleotide sequence of the hisD gene of Escherichia coli and of the hisIE region of both E. coli and Salmonella typhimurium. The hisD gene codes for a bifunctional enzyme, l-histidinol: NAD+ oxidoreductase, of 434 amino acids with a molecular mass of 46,199 daltons. We established that the hisIE region of both S. typhimurium and E. coli is composed of a single gene and not, as previously believed, of two separate genes. The derived amino acid sequence indicates that the hisIE gene codes for a bifunctional protein of 203 amino acids with an approximate molecular mass of 22,700 daltons. We also determined the nucleotide sequence of a deletion mutant in S. typhimurium which abolishes the hisF and hisI functions but retains the hisE function. We deduced that the mutant produces a chimeric protein fusing the aminoterminal region of the upstream hisF gene to the carboxylterminal domain of the hisIE gene which encodes for the hisE function. In view of these results the structural and functional organization of the histidine operon in enteric bacteria needs to be revised. The operon is composed of only 8 genes and the pathway leading to the biosynthesis of the amino acid requires 11 enzymatic steps. 相似文献