全文获取类型
收费全文 | 163篇 |
免费 | 10篇 |
出版年
2019年 | 1篇 |
2018年 | 3篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 11篇 |
2011年 | 8篇 |
2010年 | 12篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 9篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1973年 | 4篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有173条查询结果,搜索用时 15 毫秒
1.
An isocratic reverse-phase high-performance liquid chromatography method for the separation and quantitation of total pyridine dinucleotides in hepatocyte cultures is described. Cells are extracted with cold 3 M perchloric acid or 0.5 N sodium hydroxide containing 50% (v/v) ethanol and 35% cesium chloride for the determination of the oxidized or reduced pyridine dinucleotides, respectively. Pyridine dinucleotides in the neutralized extracts were separated on an Excellopak ODS C18 (4.6 X 150 mm) column with 0.1 M potassium phosphate, pH 6.0, containing 3.75% methanol as the mobile phase. NAD+ and NADP+ were detected spectrophotometrically at 254 nm. The response was linear from 5 to 4000 pmol with recoveries of NAD+ and NADP+ of 98 and 101.1%, respectively. NADH and NADPH were monitored fluorometrically by activation at 370 nm and emission in the 400-700 nm range. The reduced pyridine dinucleotides had a linear response from 7.5 to 60 pmol with recoveries of NADH and NADPH of 99.4 and 101.3%, respectively. The coefficients of variation for all of the pyridine dinucleotide standards were less than 3.5%. 相似文献
2.
3.
M F Canto M M Oliva J J Potter E Mezey V W Yang 《Biochemical and biophysical research communications》1992,188(2):684-689
The activity of the rat class I alcohol dehydrogenase (ADH) is enriched in certain tissues including the liver, intestine and testis. The tissue-specific expression of the gene encoding ADH in the rat was studied and found to closely correlate with tissue isozymic activity. A factor designated enhancer-site downstream binding protein (EDBP) was recently identified in the rat liver and found to interact with the proximal promoter of the class I ADH gene. The distribution of EDBP in nuclear extracts obtained from various tissues was examined based on its sequence-specific DNA binding property and found to correlate with tissue ADH expression. These findings suggest that EDBP is potentially a positive regulatory factor which is involved in controlling the tissue-specific expression of the ADH gene. 相似文献
4.
We have broadly defined the DNA regions regulating esterase6 activity in
several life stages and tissue types of D. melanogaster using P-
element-mediated transformation of constructs that contain the esterase6
coding region and deletions or substitutions in 5' or 3' flanking DNA.
Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and
the primary sequences regulating its activity lie between -171 and -25 bp
relative to the translation initiation site: deletion of these sequences
decrease activity approximately 20-fold. Hemolymph activity is also
modulated by four other DNA regions, three of which lie 5' and one of which
lies 3' of the coding region. Of these, two have positive and two have
negative effects, each of approximately twofold. Esterase6 activity is
present also in two male reproductive tract tissues; the ejaculatory bulb,
which is another ancestral activity site, and the ejaculatory duct, which
is a recently acquired site within the melanogaster species subgroup.
Activities in these tissues are at least in part independently regulated:
activity in the ejaculatory bulb is conferred by sequences between -273 and
-172 bp (threefold decrease when deleted), while activity in the
ejaculatory duct is conferred by more distal sequences between -844 and
-614 bp (fourfold decrease when deleted). The reproductive tract activity
is further modulated by two additional DNA regions, one in 5' DNA (-613 to
-284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to
+2731 bp; threefold decrease when deleted) that probably overlaps the
adjacent esteraseP gene. Collating these data with previous studies
suggests that expression of EST6 in the ancestral sites is mainly regulated
by conserved proximal sequences while more variable distal sequences
regulate expression in the acquired ejaculatory duct site.
相似文献
5.
Nucleotide variation at the hypervariable esterase 6 isozyme locus of Drosophila simulans 总被引:2,自引:0,他引:2
Esterase 6 (Est-6/EST6) is polymorphic in both Drosophila melanogaster and
D. simulans for two common allozyme forms, as well as for several other
less common variants. Parallel latitudinal clines in the frequencies of the
common EST6-F and EST6-S allozymes in these species have previously been
interpreted in terms of a shared amino acid polymorphism that distinguishes
the two variants and is subject to selection. Here we compare the sequences
of four D. simulans Est-6 isolates and show that overall estimates of
nucleotide heterozygosity in both coding and 5' flanking regions are more
than threefold higher than those obtained previously for this gene in D.
melanogaster. Nevertheless, the ratio of replacement to exon silent-site
polymorphism in D. simulans is less than the ratio of replacement to silent
divergence between D. simulans and D. melanogaster, which could be the
result of increased efficiency of selection against replacement
polymorphisms in D. simulans or to divergent selection between the two
species. We also find that the amino acid polymorphisms separating EST6- F
and EST6-S in D. simulans are not the same as those that separate these
allozymes in D. melanogaster, implying that the shared clines do not
reflect shared molecular targets for selection. All comparisons within and
between the two species reveal a remarkable paucity of variation in a
stretch of nearly 400 bp immediately 5' of the gene, indicative of strong
selective constraint to retain essential aspects of Est-6 promoter
function.
相似文献
6.
7.
8.
The effects of ovariectomy and administration of estradiol on the activity of liver alcohol dehydrogenase and on the rate of ethanol elimination were determined in female Sprague-Dawley rats. The activity of the enzyme and the rates of ethanol elimination in the female sham-operated animals were higher than obtained previously in male rats of the same age. Ovariectomy had no effect on liver alcohol dehydrogenase and on rates of ethanol elimination. Estradiol administration resulted in an increase in liver weight and in total liver alcohol dehydrogenase activity per animal in sham-operated but not in ovariectomized animals. The increase in enzyme activity after estradiol administration in sham-operated animals was not associated with a significant increase in the rate of ethanol elimination, suggesting that the enzyme activity in female rats is not rate-limiting in in vivo ethanol oxidation. 相似文献
9.
10.
Anton Orlin Dolan Sondhi Matthew T. Witmer Matthew M. Wessel Jason G. Mezey Stephen M. Kaminsky Neil R. Hackett Kaleb Yohay Barry Kosofsky Mark M. Souweidane Michael G. Kaplitt Donald J. D’Amico Ronald G. Crystal Szilárd Kiss 《PloS one》2013,8(8)