全文获取类型
收费全文 | 201篇 |
免费 | 17篇 |
出版年
2021年 | 2篇 |
2020年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2015年 | 3篇 |
2014年 | 13篇 |
2013年 | 5篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 11篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有218条查询结果,搜索用时 531 毫秒
211.
In a previous study we evaluated muscle blood flow and muscle metabolism in patients diagnosed with chronic fatigue syndrome (CFS). To better understand muscle metabolism in CFS, we re-evaluated our data to calculate free Magnesium levels in skeletal muscle. Magnesium is an essential cofactor in a number of cell processes. A total of 20 CFS patients and 11 controls were evaluated. Phosphorus magnetic resonance spectroscopy from the medial gastrocnemius muscle was used to calculate free Mg2+ from the concentrations and chemical shifts of Pi, PCr, and beta ATP peaks. CFS patients had higher magnesium levels in their muscles relative to controls (0.47 + 0.07 vs 0.36 + 0.06 mM, P < 0.01), although there was no difference in the rate of phosphocreatine recovery in these subjects, as reported earlier. This finding was not associated with abnormal oxidative metabolism as measured by the rate of recovery of phosphocreatine after exercise. In summary, calculation of free Mg2+ levels from previous data showed CFS patients had higher resting free Mg2+ levels compared to sedentary controls. 相似文献
212.
During the period of rapid elongation prior to the initiation of placental attachment (days 12-16 of gestation), the ovine blastocyst consists of a single layer (primarily) of roughly cuboidal trophoblastic cells with an inner lining of flattened endodermal cells. Well-developed spot desmosomes link the adjacent cell borders in both the trophoblastic and endodermal layers. The trophoblastic cells contain acid phosphatase-positive, lysosomelike organelles, the mean diameter of which increases greatly between days 12 and 16 and whose contents vary during development. Also during the developmental period studied, trophoblast cells accumulate lipid; and periodic acid-Schiff-positive binucleate cells appear within the trophoblast layer. A consistent observation throughout the 5 days of rapid growth and differentiation of the blastocyst was the death and disintegration of some trophoblast cells. These disintegrating cells are usually singly dispersed within the trophoblast, although occasionally groups of four or five are observed. The cell death may indicate overall remodelling of the blastocyst, or the cells may represent genetically deficient cells which are unable to respond to the appropriate signal to differentiate. 相似文献
213.
Sery Gonedelé Bi Didier P Sokouri Kouakou Tiékoura Oulo Alla N?Nan Marcel Lolo Félix Gnangbé Assanvo SP N?Guetta 《Bioinformation》2014,10(11):671-678
Cête d׳Ivoire continues to have the highest HIV-1 prevalence rate in West Africa, although the infection number is in constant
decline. The external envelope protein of the viruses is a likely site of selection, and responsible for receptor binding and entry into
host cells, and therefore constitutes an ideal region with which to investigate the evolutionary processes acting on HIV-1. In this
study, we analyse 189 envelope glycoprotein V3 loop region sequences of viruse isolates from 1995 to 2009, from HIV-1 untreated
patients living in Cête d׳Ivoire, to decipher the temporal relationship between disease diversity, divergence and selection. Our
analyses show that the nonsynonymous and synonymous ratio (dN/dS) was lower than 1 for viral populations analysed within 15
years, which showed the sequences did not undergo adequate immune pressure. The phylogenetic tree of the sequences analysed
demonstrated distinctly long internal branches and short external branches, suggesting that only a small number of viruses
infected the new host cell at each transmission. In addition to identifying sites under purifying selection, we also identified neutral
sites that can cause false positive inference of selection. These sites presented form a resource for future studies of selection
pressures acting on HIV-1 enν gene in Cête d׳Ivoire and other West African countries. 相似文献
214.
215.
216.
217.
218.
Human clinical and psychophysical observations suggest that the taste
system is able to compensate for losses in peripheral nerve input, since
patients do not commonly report decrements in whole mouth taste following
chorda tympani nerve damage or anesthesia. Indeed, neurophysiological data
from the rat nucleus of the solitary tract (NST) suggests that a release of
inhibition (disinhibition) may occur centrally following chorda tympani
nerve anesthesia. Our purpose was to study this possibility further. We
recorded from 59 multi- and single- unit taste-responsive sites in the rat
NST before, during and after recovery from chorda tympani nerve anesthesia.
During anesthesia, average anterior tongue responses were eliminated but no
compensatory increases in palatal or posterior tongue responses were
observed. However, six individual sites displayed increased taste
responsiveness during anesthesia. The average increase was 32.9%.
Therefore, disinhibition of taste responses was observed, but infrequently
and to a small degree in the NST At a subset of sites, chorda
tympani-mediated responses decreased while greater superficial
petrosal-mediated responses remained the same during anesthesia. Since this
effect was accompanied by a decrease in spontaneous activity, we propose
that taste compensation may result in part by a change in signal-to-noise
ratio at a subset of sites.
相似文献