全文获取类型
收费全文 | 411篇 |
免费 | 33篇 |
专业分类
444篇 |
出版年
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 19篇 |
2014年 | 18篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 19篇 |
2010年 | 29篇 |
2009年 | 25篇 |
2008年 | 16篇 |
2007年 | 20篇 |
2006年 | 16篇 |
2005年 | 18篇 |
2004年 | 19篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 10篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1991年 | 6篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 19篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有444条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
Ali Arslan Cuillermina Almazan Hans H. Zingg 《In vitro cellular & developmental biology. Animal》1995,31(2):140-148
Summary Normal and neoplastic growth of epithelial cells depends on mutual interactions between epithelial and stromal cells. As a
tool for the study of the underlying molecular mechanisms, we have developed temperature-sensitive, nontransformed cell lines
derived from rat uterine epithelium and stroma by transfecting primary cultures with a temperature-sensitive mutant of the
SV40 large T antigen. The epithelial and stromal cell lines obtained shared relevant morphological characteristics with the
primary cells from which they were derived. Immunocytochemical analysis showed that the epithelial cell lines expressed the
intermediate filament cytokeratin, whereas the stromal lines expressed the intermediate filament vimentin. Alkaline phosphatase
activity was present in all cell lines examined. All cell lines were anchorage dependent and did not form foci. One epithelial
cell line expressed oxytocin mRNA, a gene product recently shown to be highly expressed in vivo in the uterine epithelium
at term. If grown on Matrigel, this cell line formed domelike structures, a further characteristic of its differentiated phenotype.
In an attempt to reconstitute an endometrium in vitro, epithelial cells were seeded on top of a layer of stromal cells. Paraffin
cross sections showed that this in vitro system consisted of a bilayer structure. Four to five cuboidal epithelial cells were
typically anchored atop one stromal cell, forming an endometriumlike tissue. The present in vitro system should provide a
useful model for further studies on endometrial functions and epithelial/stromal cell interactions at a molecular level. 相似文献
5.
HhaI and HpaII DNA methyltransferases bind DNA mismatches, methylate uracil and block DNA repair. 总被引:10,自引:7,他引:3 下载免费PDF全文
The hydrolytic deamination of 5-methylcytosine (5-mC) to thymine (T) is believed to be responsible for the high mutability of the CpG dinucleotide in DNA. We have shown a possible alternate mechanism for mutagenesis at CpG in which HpaII DNA-(cytosine-5) methyltransferase (M.HpaII) can enzymatically deaminate cytosine (C) to uracil (U) in DNA [Shen, J.-C., Rideout, W.M., III and Jones, P.A., Cell, 71, 1073-1080, (1992)]. Both the hydrolytic deamination of 5-mC and enzymatic deamination of C create premutagenic DNA mismatches (G:U and G:T) with the guanine (G) originally paired to the normal C. Surprisingly, we found that DNA-(cytosine-5) methyltransferases have higher affinities for these DNA mismatches than for their normal G:C targets and are capable of transferring a methyl group to the 5-position of U, creating T at low efficiencies. This binding by methyltransferase to mismatches at the recognition site prevented repair of G:U mismatches by uracil DNA glycosylase in vitro. 相似文献
6.
7.
8.
9.
Different vascular suturing techniques were assessed in the experimental laboratory. Staples made of tantulum wire were employed for vascular anastomoses in normal dogs'' arteries and veins and in atherosclerotic rabbits'' aortas. The staples were driven with the NRC Vascular Suturing Instrument. In a similar series of experiments a plastic bonding agent (Eastman 910) was used. The anastomosed vessels were found to be patent and few complications were encountered. However, it is unlikely that the conventional suture technique with the currently available materials will be replaced by these methods except under special circumstances. Clinical application of the stapling method is envisaged in the anastomosis of small vessels and in situations when speed is essential, whereas the bonding agent promises to be useful as an ancillary method in combination with sutures or staples. 相似文献
10.