全文获取类型
收费全文 | 762篇 |
免费 | 80篇 |
专业分类
842篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 23篇 |
2020年 | 10篇 |
2019年 | 23篇 |
2018年 | 25篇 |
2017年 | 25篇 |
2016年 | 41篇 |
2015年 | 32篇 |
2014年 | 32篇 |
2013年 | 55篇 |
2012年 | 51篇 |
2011年 | 47篇 |
2010年 | 38篇 |
2009年 | 35篇 |
2008年 | 25篇 |
2007年 | 31篇 |
2006年 | 27篇 |
2005年 | 22篇 |
2004年 | 26篇 |
2003年 | 18篇 |
2002年 | 21篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有842条查询结果,搜索用时 15 毫秒
1.
2.
Action of endogenous prostaglandins on postprandial pyloric motility: a possible modulation by fats.
The involvement of endogenous prostaglandins (PGs) and the effect of exogenous PGs on the myoelectrical activity of the pylorus were examined for 6 hours after a meal in dogs chronically fitted with intraparietal electrodes on the gastroduodenal junction. The animals received either a standard meal or a fat meal which consisted of canned food added or not (standard meal) with arachis oil. The cyclooxygenase inhibitors, indomethacin (1 mg/kg) and piroxicam (0.2 mg/kg) given prior a fat meal significantly increased the frequency of pyloric spike bursts but did not modify the pyloric motility associated with a standard meal. Synthetic derivatives of PGE1 (misoprostol, 5-10 micrograms/kg) or PGE2 (enprostil 0.5-1 micrograms/kg) reduced the frequency of pyloric contractions after a fat but not a standard meal. It is suggested that both endogenous and exogenous prostaglandins may modulate postprandial pyloric motility when fats are present in sufficient amount into the meal. 相似文献
3.
4.
A Lanas J Alcalde M Montoro F Gomollon J Morandeira J Bueno R Sainz 《Revista Espanola de Fisiología》1985,41(3):335-339
Gastrin serum levels after acidification of the second portion of the duodenum were studied, in dogs and humans, while simultaneously measuring secretin levels and gastric acid secretion. After duodenal acidification in dogs, a 50% inhibition of gastric acid secretion with parallel 100% increases in the serum secretin levels was noted whereas gastrin serum levels did not change (after duodenal acidification). In humans, a 25% inhibition of gastric acid secretion with parallel 50% (not significative) increases in the secretin serum levels was noted. In the entire group gastrin levels did not change, but in 35.2% of the subjects a little increment without statistical significance was noted. It is concluded that the inhibition mechanism of gastric acid secretion after duodenal acidification is more important in dog than in man, and that, probably, gastrin does not play an important role in this mechanism. 相似文献
5.
The effects of intracerebroventricular (ICV) and intrathecal (IT) administration of calcitonin gene-related peptide (CGRP) on intestinal motility were examined in conscious rats chronically fitted with intraparietal electrodes in the duodeno-jejunum and a cannula in a cerebral lateral ventricle or catheter in the subarachnoid space. ICV administration of CGRP (0.5–10 μg) restores the fasted pattern of intestinal motility in fed rats in a dose-related manner. Intrathecal administration of CGRP or calcitonin also induces fasted pattern but after a 30 min delay. These effects persisted after transection of the spinal cord and no change in intestinal motility appeared after intravenous administration of CGRP at a dose effective when given IT. This study suggests that CGRP, as calcitonin, has a neuromodulatory role in the control of intestinal motility at both brain and spinal cord levels. 相似文献
6.
Nitrogen regulation system of Klebsiella aerogenes: the nac gene. 总被引:17,自引:12,他引:5
In Klebsiella aerogenes, the product of a his-linked gene, nac, appears to play a crucial role in tying the synthesis of enzymes activated or repressed by ammonia deprivation, such as histidase and glutamate dehydrogenase, to the known regulators of nitrogen assimilation, the products of glnG and glnF. 相似文献
7.
Multivariate morphometrics and allometry in a polymorphic ant 总被引:1,自引:0,他引:1
8.
The pea aphidAcyrthosiphon pisum (Harris) and the blue alfalfa aphidA. kondoi Shinji are pests of alfalfaMedicago sativa L. worldwide. The parasitoidAphidium ervi Haliday attacks both species andA. smithi is host specific to pea aphid Experiments were conducted to determine the preference ofA. ervi forA. pisum andA. kondoi at three densities of hosts using the percentages of parasitism and superparasitism, and the distribution of eggs among hosts as criteria. Also examined was the outcome of competition between the two parasitoids when exposed to the same hosts. A. ervi attacks moreA. pisum when provided alone (no choice test) and when provided together in equal numbers withA. kondoi (choice test). There was no significant difference in the number of progeny produced by either parasitoid when a female of each species was introduced simultaneously into the same test unit containingA. pisum hosts. The effects of the pathogenPandora neoaphidis on this competition is reviewed. 相似文献
9.
10.
João Ricardo Sato Claudinei Eduardo Biazoli Ana Paula Arantes Bueno Arthur Caye Pedro Mario Pan Marcos Santoro Jessica Honorato-Mauer Giovanni Abrahão Salum Marcelo Queiroz Hoexter Rodrigo Affonseca Bressan Andrea Parolin Jackowski Euripedes Constantino Miguel Sintia Belangero Luis Augusto Rohde 《Genes, Brain & Behavior》2023,22(2):e12838