全文获取类型
收费全文 | 338篇 |
免费 | 39篇 |
出版年
2023年 | 3篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 14篇 |
2014年 | 12篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 17篇 |
2010年 | 12篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 9篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1970年 | 3篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1966年 | 2篇 |
排序方式: 共有377条查询结果,搜索用时 125 毫秒
1.
2.
The resting release of acetylcholine by a retinal neuron 总被引:2,自引:0,他引:2
R H Masland C Cassidy 《Proceedings of the Royal Society of London. Series B, Containing papers of a Biological character. Royal Society (Great Britain)》1987,232(1267):227-238
The cholinergic amacrine cells of the rabbit retina secrete acetylcholine by two mechanisms. One is activated by stimulation of the retina by light or depolarization of the amacrine cells by K+ ions. It requires the presence of extracellular Ca2+. The second is independent of extracellular Ca2+ and is unaffected by large depolarizations of the cells. It bears some similarity to the acetylcholine 'leakage' described at the neuromuscular junction. Although the Ca2+-independent mechanism accounts for about two thirds of the total acetylcholine release in the dark, the amount of acetylcholine released in this way is small compared with the release of acetylcholine triggered by stimulation of the retina with light. Its biological significance is unclear. 相似文献
3.
Cassidy S. S.; Ashton J. H.; Wead W. B.; Kaufman M. P.; Monsereenusorn Y.; Whiteside J. A. 《Journal of applied physiology》1986,60(3):949-958
The purpose of these studies was to determine quantitatively the reflex cardiovascular responses to stimulation of the pulmonary C-fibers in dogs. We used a preparation in which the airway, pulmonary artery, and the pulmonary veins to the left lung were cannulated in situ. Ventilation and perfusion of the right lung maintained the animal in relatively normal homeostasis. Capsaicin, a decylenic acid amide of vanillylamine that selectively stimulates nerve endings of unmyelinated fibers (C-fibers), was injected into the left pulmonary artery in 5-ml boluses. Maximal reflex responses were obtained with concentrations as low as 0.8-1.6 X micrograms-1 X kg-1. Heart rate, hindlimb resistance, and left ventricular contractility were lowered transiently (the maximal responses showing declines of 40, 13, and 15.2%, respectively). As a result of these changes, combined with vasodilation in other resistance vessels, cardiac output fell 28% and blood pressure fell 35%. Interrupting the afferent neural pathway by severing the ipsilateral cervical vagus nerve eliminated these responses, confirming the distribution of their reflex origin. Although the role of these reflexes in homeostasis has not been decided, the results of this study suggest that the lungs of dogs, if appropriately stimulated, potentially can exert a major inhibitory influence on the neural regulation of cardiovascular function. 相似文献
4.
5.
Cassidy S. S.; Wead W. B.; Seibert G. B.; Ramanathan M. 《Journal of applied physiology》1987,63(2):803-811
The purpose of these experiments was to determine the effects of a spontaneously generated inspiration on the size and shape of the left ventricle (LV) in anesthetized supine dogs. We implanted markers in the LV to establish three perpendicular axes and recorded the motion of these markers using biplane cinefluoroscopy at 60 Hz. The primary changes in LV size that accompanied inspiration occurred at end diastole (ED). The largest change in LVED dimension was a 2.46-mm narrowing of the septal-lateral wall dimension, but the apex-base dimension decreased also, by 0.74 mm. The anteroposterior dimension actually widened by 1.07 mm. The septal-lateral narrowing was caused by both a 1.0-mm narrowing of the distance between the septal marker and the apex-base axis, as well as by a 1.4-mm narrowing between the apex-base axis and the lateral wall marker. Narrowing of the septal portion seemed expected because of presumed enhanced right ventricular filling during inspiration. Narrowing of the lateral portion of the LV, while the anteroposterior dimension widened, was surprising because a change in LVEDV shape is implied. Assuming ventricular homogeneity, this change in LVED shape implies that the forces applied to the epicardial surface were not uniform. There must have been a retraction on the anterior and posterior surface that was not experienced by the lateral LV wall. The net effect of these dimensional changes of the LV at end diastole (estimated from the product of the three ED axes) was a 3.5-cm3 reduction in LVED volume.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
6.
7.
8.
N. G. Cassidy 《Plant and Soil》1968,28(3):390-406
Summary A previous paper (Part I)4 has shown that when vegetation and land slope are favourable to the capture of aerosol, the salinity of rainfall provides no measure of rate of acquisition of cyclic salt by a given land area.This is confirmed by the high level of chloride in Fiji foliage.The chloride content of experimental rice plants was found to be much higher than could be accounted for by all the chlorides introduced into the growth medium.Rice plants in the field, affected by the punctures of leaf hoppers, were shown to have a higher level of leaf chloride than unaffected plants.Chloride absorbed through the leaves was distributed in the plant differently from chloride taken up by the roots.Measurements on stomata and specific leaf area suggest that the aerosol particles enter through the stomata rather than through the rest of the leaf surface. 相似文献
9.
10.
Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves 总被引:4,自引:0,他引:4
A puzzling population-genetic phenomenon widely reported in allozyme
surveys of marine bivalves is the occurrence of heterozygote deficits
relative to Hardy-Weinberg expectations. Possible explanations for this
pattern are categorized with respect to whether the effects should be
confined to protein-level assays or are genomically pervasive and expected
to be registered in both protein- and DNA-level assays. Anonymous nuclear
DNA markers from the American oyster were employed to reexamine the
phenomenon. In assays based on the polymerase chain reaction (PCR), two
DNA-level processes were encountered that can lead to artifactual genotypic
scorings: (a) differential amplification of alleles at a target locus and
(b) amplification from multiple paralogous loci. We describe symptoms of
these complications and prescribe methods that should generally help to
ameliorate them. When artifactual scorings at two anonymous DNA loci in the
American oyster were corrected, Hardy-Weinberg deviations registered in
preliminary population assays decreased to nonsignificant values.
Implications of these findings for the heterozygote-deficit phenomenon in
marine bivalves, and for the general development and use of PCR-based
assays, are discussed.
相似文献