全文获取类型
收费全文 | 1240篇 |
免费 | 140篇 |
专业分类
1380篇 |
出版年
2021年 | 18篇 |
2018年 | 24篇 |
2016年 | 11篇 |
2015年 | 31篇 |
2014年 | 45篇 |
2013年 | 50篇 |
2012年 | 60篇 |
2011年 | 49篇 |
2010年 | 32篇 |
2009年 | 27篇 |
2008年 | 49篇 |
2007年 | 29篇 |
2006年 | 31篇 |
2005年 | 33篇 |
2004年 | 39篇 |
2003年 | 35篇 |
2002年 | 43篇 |
2001年 | 33篇 |
2000年 | 28篇 |
1999年 | 34篇 |
1997年 | 11篇 |
1995年 | 15篇 |
1994年 | 15篇 |
1993年 | 13篇 |
1992年 | 23篇 |
1991年 | 29篇 |
1990年 | 28篇 |
1989年 | 30篇 |
1988年 | 28篇 |
1987年 | 25篇 |
1986年 | 27篇 |
1985年 | 23篇 |
1984年 | 14篇 |
1983年 | 22篇 |
1982年 | 17篇 |
1980年 | 12篇 |
1979年 | 20篇 |
1977年 | 13篇 |
1976年 | 12篇 |
1974年 | 18篇 |
1973年 | 16篇 |
1972年 | 13篇 |
1971年 | 17篇 |
1970年 | 11篇 |
1969年 | 20篇 |
1968年 | 11篇 |
1967年 | 15篇 |
1966年 | 18篇 |
1965年 | 11篇 |
1964年 | 13篇 |
排序方式: 共有1380条查询结果,搜索用时 0 毫秒
51.
52.
Injection of morphine or d-ala-2-met-5-enkephalinamide (DALA) into the paraventricular nucleus of the hypothalamus (PVN) produced a dose dependent increase in feeding in rats. DALA increased feeding within 45 minutes; morphine within 90 minutes. Naloxone injected into the PVN diminished the effect. DALA increased water intake only when food was available, suggesting the primary effect was on feeding. In summary, an enkephalin analogue induced feeding, and an opiate receptor blocker attenuated it; therefore the PVN may contain opiate receptors that facilitate feeding. 相似文献
53.
Cloned aerolysin of Aeromonas hydrophila is exported by a wild-type marine Vibrio strain but remains periplasmic in pleiotropic export mutants. 总被引:2,自引:1,他引:1 下载免费PDF全文
With a wide host range vector, the structural gene aerA for the hole-forming extracellular protein aerolysin of Aeromonas hydrophila was cloned into the marine Vibrio sp. strain 60 and into three pleiotropic export mutants (epr mutants). The parent strain and all of the mutants were able to express the protein with the aerA promoter in the plasmid. The parent strain exported proaerolysin into the medium, while all of the mutants accumulated the protoxin in their periplasms. Two of the mutants also accumulated protease; however, as we have found earlier with A. hydrophila, the periplasmic form of proaerolysin in the Vibrio sp. must somehow be protected from proteolysis because it was not converted to active toxin until the cells were shocked. Conversion could be prevented by adding o-phenanthroline to the solutions used in shocking. These results show that the export pathway in the marine Vibrio sp. is very similar to the pathway in A. hydrophila. 相似文献
54.
Isolation and characterization of the human hepatic lipase gene 总被引:7,自引:0,他引:7
D Ameis G Stahnke J Kobayashi J McLean G Lee M Büscher M C Schotz H Will 《The Journal of biological chemistry》1990,265(12):6552-6555
55.
John S. Hothersall Salmata Zubairu Patricia McLean A. Leslie Greenbaum 《Journal of neurochemistry》1981,37(6):1484-1496
The effect of 6-aminonicotinamide (6AN) treatment on the activities of alternative pathways of glucose metabolism in 20-day-old rat brain was evaluated by measurements of yields of 14CO2 from glucose labeled with 14C on carbons 1, 2, 3 + 4, or 6 and uniformly labeled glucose, and from the incorporation of 14C from specifically labeled glucose into lipids by brain slices from cerebral hemispheres and cerebellum. At the highest dose of 6AN used (35 mg/kg body weight) there was a significant decrease in the 14CO2 yields via the pentose phosphate pathway, the glycolytic route, tricarboxylic acid (TCA) cycle, and via the glutamate-gamma-aminobutyric acid pathway. Giving a graded series of doses (20-35 mg 6AN/kg body weight) revealed a hierarchy of responses in which the pentose phosphate pathway, lactate, glyceride-glycerol, and fatty acid formation were most sensitive, followed, in sequence, by the pyruvate dehydrogenase reaction, the glutamate-gamma-aminobutyrate route and, finally, the TCA cycle. The nature of the blocks in the various pathways was examined by the use of metabolite profiles. 相似文献
56.
Effect of experimental diabetes on glycolytic intermediates and regulation of phosphofructokinase in rat lens 总被引:1,自引:0,他引:1
A M Gonzalez M Sochor P McLean 《Biochemical and biophysical research communications》1980,95(3):1173-1179
The pattern of glycolytic intermediates in the lens of alloxan-diabetic rats was indicative of regulation at phosphofructokinase. The changes in metabolites influencing phosphofructokinase activity in the diabetic, relative to the normal, rat lens were: glucose 6-phosphate, 182%; fructose 6-phosphate, 107%; fructose diphosphate, 57%. There was also a marked decrease in phosphoenolpyruvate, pyruvate, lactate and ATP but no significant change in other triose phosphates or cyclic AMP. The resuts are considered in relation to the early changes in [Ca2+] known to occur in lens in diabetes and to the coordinating effect of fructose diphosphate on flux through the glycolytic route. 相似文献
57.
Summary The electron-dense capsule tip (apical cap) of sea anemone and coral spirocysts is of a different structure than the capsule wall. The capsule wall is composed of a double layer of fiber-like materials which cross each other at roughly right angles. The innermost layer is characterized by numerous serrations, the tips of which project into the lumen of the capsule. Within each serration, a band of finely cross-striated material encircles the capsule at right angles to its longitudinal axis. The membrane lining the lumen of the capsule appears to be continuous with the wall of the undischarged thread. The outer capsule wall layer consists of closely spaced microfilaments (cnidofilaments) which are oriented in the longitudinal axis of the capsule. The cnidofilaments appear to merge with the apical cap material. Contrary to some previous reports in the literature, it has been found that spirocysts normally discharge by eversion, as do nematocysts. The relationship of the capsule wall sub-structure to the spirocyst discharge process is discussed.Thanks are due Dr. Cadet Hand for the use of the facilities of the Bodega Marine Laboratory of the University of California and B. Miller, F. Doroshow, C. Bigger, G. Chapman and E. Chang for expert technical assistance. The use of the facilities of the Electron Microscope Laboratory and Electronics Research Laboratory of the University of California at Berkeley and the Eelectron Microscope Laboratory of the Florida State University is gratefully acknowledged. Part of this work was made possible by NSF Grant GB-40547 to the senior author 相似文献
58.
Summary The presence of aromatic 1-amino acid decarboxylase (AADC) in nerve cell bodies of the intrinsic plexuses of the guinea-pig small intestine was demonstrated by incubating segments of intestine with 1-dopa in the presence of an inhibitor of monoamine oxidase, pargyline. After such incubation, some nerve cell bodies gave a fluorescence histochemical reaction indicative of the presence of a decarboxylated product of 1-dopa, probably dopamine. No fluorescence reaction occurred in the unincubated control or if the inhibitor of AADC, RO 4-4602, was included in the incubation mixture. The AADC-containing cell bodies apparently do not take up and store dopamine, because no fluorescence could be detected after incubation with dopamine and a monoamine oxidase inhibitor. The AADC-containing cells were found in about half of the ganglia of the submucous plexus of the guinea-pig small intestine, but were considerably less frequent in the myenteric plexus. They were also found in the other areas examined in this study, that is, in both enteric plexuses of the guinea-pig distal colon and of the small intestines of rabbits and rats. 相似文献
59.
Analytical refinements in animal calorimetry 总被引:1,自引:0,他引:1
60.
Najma Zaheer Baquer John S. Hothersall A.L. Greenbaum Patricia McLean 《Biochemical and biophysical research communications》1975,62(3):634-641
The effect of Mn2+ on the pattern of emergence of enzymes in rat liver and adipose tissue was studied in weaned rats given a milk diet (high fat) or sucrose-casein diet (high carbohydrate) for three weeks. Addition of Mn2+ to the high fat diet was associated with induction of key glycolytic, lipogenic and pentose pathway enzymes in both liver and adipose tissue; parallel increases were found in the incorporation of [1-14C] glucose into lipid and CO2. Mn2+ induced a change in the profile of enzyme activity similar in pattern to that found in rats given a high sucrose diet or that produced by insulin treatment. Mn2+ appears partially to overcome the regulatory feed-back mechanisms of the high fat diet and to provide a signal for the coordinated increase of glucose catabolic and lipogenic processes. 相似文献