全文获取类型
收费全文 | 94篇 |
免费 | 6篇 |
出版年
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 5篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 6篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2003年 | 1篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有100条查询结果,搜索用时 15 毫秒
41.
Scoggins CR Meszoely IM Wada M Means AL Yang L Leach SD 《American journal of physiology. Gastrointestinal and liver physiology》2000,279(4):G827-G836
The mechanisms linking acinar cell apoptosis and ductal epithelial proliferation remain unknown. To determine the relationship between these events, pancreatic duct ligation (PDL) was performed on p53(+/+) and p53(-/-) mice. In mice bearing a wild-type p53 allele, PDL resulted in upregulation of p53 protein in both acinar cells and proliferating duct-like epithelium. In contrast, upregulation of Bcl-2 occurred only in duct-like epithelium. Both p21(WAF1/CIP1) and Bax were also upregulated in duct-ligated lobes. After PDL in p53(+/+) mice, acinar cells underwent widespread apoptosis, while duct-like epithelium underwent proliferative expansion. In the absence of p53, upregulation of p53 target genes and acinar cell apoptosis did not occur. The absence of acinar cell apoptosis in p53(-/-) mice also eliminated the proliferative response to duct ligation. These data demonstrate that PDL-induced acinar cell apoptosis is a p53-dependent event and suggest a direct link between acinar cell apoptosis and proliferation of duct-like epithelium in duct-ligated pancreas. 相似文献
42.
Rotchell JM Scoggins B Blair JB Ostrander GK 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2001,130(3):385-391
The retinoblastoma (Rb) gene represents the first tumor suppressor gene characterized. The encoded protein, pRb, plays a crucial role in cell cycle control, preventing malignant cell proliferation. Recently, homologues of the Rb gene have been isolated in fish and the pocket domain, which is central to Rb function, was conserved. In our studies, using coelocanth (Latimeria chalumnae), rainbow trout (Oncorhynchus mykiss), medaka (Oryzias latipes) and English sole (Parophrys vetulus), we have developed a simple protocol for the isolation of the Rb tumor suppressor protein and determined its' tissue and cellular localization. Fish Rb proteins display apparent molecular weights in the range of 100-110 kDa, similar to the human pRb. The protein was detected in all tissues examined, consistent with the proteins' universal role in cellular signalling. An interesting pattern of immunoreactive bands was detected in each of the cells' two main compartments, suggesting differential proteolysis. Immuno-analysis of the pRb in trout liver tumor material revealed an additional Rb reactive product that was absent in normal liver cell extracts. 相似文献
43.
David T.W. Fei William F. Graham John G. McDougal Bruce A. Scoggins John P. Coghlan 《Life sciences》1980,27(16):1495-1502
The present study describes an improved method for measuring angiotensin III in arterial blood. This was accomplished by SE-sephadex column to separate angiotensin II from angiotensin III prior to radioimmunoassay. The arterial concentration of angiotensin III measured before and after 24 to 48 hours sodium depletion by acute cannulation of parotid gland was 12.4 ± 1.7 fmol/ml (SEM, n=7) and 49.8 ± 10.3 fmol/ml (SEM, n=7) respectively. The arterial concentration of Val4-angiotensin III obtained from continuous infusion of Val4-angiotensin III at rates of 24 and 48 nmol/h in sodium deficient sheep were 245 ± 32.5 fmol/ml (n=6) and 330 ± 11.4 fmol/ ml (n=7) respectively. The clearance rate of exogenous Val4-angiotensin III in sodium deficient sheep after correction for endogenous level was calculated to be 140 ± 13.6 L/h (SEM, n=13). This was in the same order as Ile5-angiotensin II and Ile4-angiotensin III reported earlier in sodium replete sheep. Prolonged intravenous infusion of Val4-angiotensin III at a rate of 48 nmol/h in sodium- deficient sheep suppressed plasma renin concentration to the same extent as equimolar infusions of angiotensin II. This suggests that angiotensin III may inhibit renin secretion by a similar mechanism to angiotensin II. 相似文献
44.
45.
46.
Y Deng J Zhao D Sakurai KM Kaufman JC Edberg RP Kimberly DL Kamen GS Gilkeson CO Jacob RH Scofield CD Langefeld JA Kelly ME Alarcón-Riquelme BIOLUPUS GENLES Networks JB Harley TJ Vyse BI Freedman PM Gaffney KM Sivils JA James TB Niewold RM Cantor W Chen BH Hahn EE Brown PROFILE BP Tsao 《Arthritis research & therapy》2012,14(Z3):A5
47.
Background
Pichia stipitis xylose reductase (Ps-XR) has been used to design Saccharomyces cerevisiae strains that are able to ferment xylose. One example is the industrial S. cerevisiae xylose-consuming strain TMB3400, which was constructed by expression of P. stipitis xylose reductase and xylitol dehydrogenase and overexpression of endogenous xylulose kinase in the industrial S. cerevisiae strain USM21. 相似文献48.
Reduced natural selection associated with low recombination in Drosophila melanogaster 总被引:8,自引:1,他引:7
Synonymous codons are not used equally in many organisms, and the extent of
codon bias varies among loci. Earlier studies have suggested that more
highly expressed loci in Drosophila melanogaster are more biased,
consistent with findings from several prokaryotes and unicellular
eukaryotes that codon bias is partly due to natural selection for
translational efficiency. We link this model of varying selection intensity
to the population-genetics prediction that the effectiveness of natural
selection is decreased under reduced recombination. In analyses of 385 D.
melanogaster loci, we find that codon bias is reduced in regions of low
recombination (i.e., near centromeres and telomeres and on the fourth
chromosome). The effect does not appear to be a linear function of
recombination rate; rather, it seems limited to regions with the very
lowest levels of recombination. The large majority of the genome apparently
experiences recombination at a sufficiently high rate for effective natural
selection against suboptimal codons. These findings support models of the
Hill-Robertson effect and genetic hitchhiking and are largely consistent
with multiple reports of low levels of DNA sequence variation in regions of
low recombination.
相似文献
49.
Kappa-chain constant-region gene sequences in genus Rattus: coding regions are diverging more rapidly than noncoding regions 总被引:2,自引:0,他引:2
We have determined the nucleotide sequence of a 1,200-base pair (bp)
genomic fragment that includes the kappa-chain constant-region gene (C
kappa) from two species of native Australian rodents, Rattus leucopus
cooktownensis and Rattus colletti. Comparison of these sequences with each
other and with other rodent C kappa genes shows three surprising features.
First, the coding regions are diverging at a rate severalfold higher than
that of the nearby noncoding regions. Second, replacement changes within
the coding region are accumulating at a rate at least as great as that of
silent changes. Third, most of the amino acid replacements are localized in
one region of the C kappa domain--namely, the carboxy-terminal "bends" in
the alpha-carbon backbone. These three features have previously been
described from comparisons of the two allelic forms of C kappa genes in R.
norvegicus. These data imply the existence of considerable evolutionary
constraints on the noncoding regions (based on as yet undetermined
functions) or powerful positive selection to diversify a portion of the
constant-region domain (whose physiological significance is not known).
These surprising features of C kappa evolution appear to be characteristic
only of closely related C kappa genes, since comparison of rodent with
human sequences shows the expected greater conservation of coding regions,
as well as a predominance of silent nucleotide substitutions within the
coding regions.
相似文献
50.
The rapid hemodynamic effects of several N- and C-terminal deleted fragments of ANF, a potent ANF analogue and the recently characterised brain natriuretic peptide (BNP) were investigated in conscious sheep, and compared to the rapid hemodynamic actions of ANF 1-28. The hypotensive potency of all peptides studied was as follows: ANF 1-28 = PLO58 greater than 5-27 = ANF 5-28 = BNP greater than ANF 7-28 greater than ANF 13-28 = ANF 5-25. All peptides reduced blood pressure via a decrease in total peripheral resistance, excluding ANF 5-25 and 13-28 which were without effect on any parameter measured. These changes were associated with reflex increases in both heart rate and cardiac output, and a slight reduction in stroke volume. The duration of hypotensive/vasodilator action of ANF 1-28, 5-27, 5-28, 7-28 and BNP was approximately 3-4 minutes, whereas that of PLO58 was 7-8 minutes. In conclusion, amino acid deletions from the C- and N-terminal of the ANF molecule reduced the hypotensive/vasodilator potency of the peptide in conscious sheep. BNP produced similar rapid hemodynamic changes to ANF 1-28, suggesting that the two peptides may co-regulate blood pressure and possibly body fluids to promote fluid and cardiovascular homeostasis. 相似文献