全文获取类型
收费全文 | 350篇 |
免费 | 108篇 |
国内免费 | 3篇 |
出版年
2021年 | 4篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 24篇 |
2011年 | 32篇 |
2010年 | 11篇 |
2009年 | 17篇 |
2008年 | 26篇 |
2007年 | 17篇 |
2006年 | 18篇 |
2005年 | 17篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 21篇 |
1999年 | 7篇 |
1998年 | 14篇 |
1997年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有461条查询结果,搜索用时 31 毫秒
21.
Study of the fine structure of adeno-associated virus DNA with bacterial restriction endonucleases. 总被引:14,自引:11,他引:3
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A physical map of the adeno-associated virus type 2 genome has been constructed on the basis of the five fragments produced by the restriction endonucleases HindII + III from Hemophilus influenzae. There are three endo R-HindII cleavage sites and one endo R-HindIII site. Evidence has been obtained to support the existence of two nucleotide sequence permutations in adeno-associated virus DNA, the start points of which have been estimated to be separated by 1% of the genome. The three cleavage fragments produced by endo R-Eco RI have been ordered and oriented with respect to the endo R-HindII + III cleavage map. 相似文献
22.
Abstract Previous studies employing a single strain of the photosynthetic bacterium Rhodopseudomonas capsulata have demonstrated that this organism, which normally is not capable of growth on glycerol, can gain glycerol-utilizing ability through mutational events. We have examined other strains of R. capsulata of divergent geographic origin, and have found that they could also be converted to a glycerol-catabolic phenotype. Mutant derivatives were found to express high constitutive levels of glycerophosphate dehydrogenase (GPD) and glycerokinase (GK) which were barely detectable in the parental strains. These results suggest that the ability to utilize glycerol after undergoing a gain of function mutation is a widespread property of R. capsulata . 相似文献
23.
24.
25.
Satish Srinivasan Joseph Spear Karunakaran Chandran Joy Joseph Balaraman Kalyanaraman Narayan G. Avadhani 《PloS one》2013,8(10)
Previously we showed that Protein kinase A (PKA) activated in hypoxia and myocardial ischemia/reperfusion mediates phosphorylation of subunits I, IVi1 and Vb of cytochrome c oxidase. However, the mechanism of activation of the kinase under hypoxia remains unclear. It is also unclear if hypoxic stress activated PKA is different from the cAMP dependent mitochondrial PKA activity reported under normal physiological conditions. In this study using RAW 264.7 macrophages and in vitro perfused mouse heart system we investigated the nature of PKA activated under hypoxia. Limited protease treatment and digitonin fractionation of intact mitochondria suggests that higher mitochondrial PKA activity under hypoxia is mainly due to increased sequestration of PKA Catalytic α (PKAα) subunit in the mitochondrial matrix compartment. The increase in PKA activity is independent of mitochondrial cAMP and is not inhibited by adenylate cyclase inhibitor, KH7. Instead, activation of hypoxia-induced PKA is dependent on reactive oxygen species (ROS). H89, an inhibitor of PKA activity and the antioxidant Mito-CP prevented loss of CcO activity in macrophages under hypoxia and in mouse heart under ischemia/reperfusion injury. Substitution of wild type subunit Vb of CcO with phosphorylation resistant S40A mutant subunit attenuated the loss of CcO activity and reduced ROS production. These results provide a compelling evidence for hypoxia induced phosphorylation as a signal for CcO dysfunction. The results also describe a novel mechanism of mitochondrial PKA activation which is independent of mitochondrial cAMP, but responsive to ROS. 相似文献
26.
One unresolved issue in geomicrobiology is the involvement of microbial activity in the formation of secondary mineral deposits, or speleothems, in caves. Although there is extensive literature demonstrating the importance of bacteria in the precipitation of calcite in noncave environments, the role that these organisms play within caves remains unclear. Evidence in support of microbial involvement in deposition of speleothems has often not been compelling. Following the "Rules for the Hunt" first proposed by Schopf and Walter to determine whether structures in rock were biogenic in origin, we propose a similar set of guidelines for evaluation of microbial association with cave features. We also illustrate methods that may help unravel the complex problem of microorganism involvement in secondary mineral deposition in caves. 相似文献
27.
Daryl R. Trumbo Stephen F. Spear Jason Baumsteiger Andrew Storfer 《Molecular ecology》2013,22(5):1250-1266
A species' genetic structure often varies in response to ecological and landscape processes that differ throughout the species' geographic range, yet landscape genetics studies are rarely spatially replicated. The Cope's giant salamander (Dicamptodon copei) is a neotenic, dispersal‐limited amphibian with a restricted geographic range in the Pacific northwestern USA. We investigated which landscape factors affect D. copei gene flow in three regions spanning the species' range, which vary in climate, landcover and degree of anthropogenic disturbance. Least cost paths and Circuitscape resistance analyses revealed that gene flow patterns vary across the species' range, with unique combinations of landscape variables affecting gene flow in different regions. Populations in the northern coastal portions of the range had relatively high gene flow, largely facilitated by stream and river networks. Near the southeastern edge of the species' range, gene flow was more restricted overall, with relatively less facilitation by streams and more limitation by heat load index and fragmented forest cover. These results suggested that the landscape is more difficult for individuals to disperse through at the southeastern edge of the species' range, with terrestrial habitat desiccation factors becoming more limiting to gene flow. We suggest that caution be used when attempting to extrapolate landscape genetic models and conservation measures from one portion of a species' range to another. 相似文献
28.
Currently, schistosomiasis in China provides an excellent example of many of the challenges of moving from low transmission to the elimination of transmission for infectious diseases generally. In response to the surveillance dimension of these challenges, we here explore two strategic approaches to inform priorities for the development of improved methods addressed specifically to schistosomiasis in the low transmission environment. We utilize an individually-based model and the exposure data used earlier to explore surveillance strategies, one focused on exposure assessment and the second on our estimates of variability in individual susceptibility in the practical context of the current situation in China and the theoretical context of the behavior of transmission dynamics near the zero state. Our findings suggest that individual susceptibility is the major single determinant of infection intensity in both the low and medium risk environments. We conclude that there is considerable motivation to search for a biomarker of susceptibility to infection in humans, but that there would also be value in a method for monitoring surface waters for the free-swimming forms of the parasite in endemic or formerly endemic environments as an early warning of infection risk. 相似文献
29.
Critical thermal maxima and hematology for juvenile Atlantic (Acipenser oxyrinchus Mitchill 1815) and shortnose (Acipenser brevirostrum Lesueur, 1818) sturgeons
下载免费PDF全文
![点击此处可从《Zeitschrift fur angewandte Ichthyologie》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The critical thermal maximum (CTmax) and the associated hematological response of juvenile (~145 g, n = 8 for both species) Atlantic Acipenser oxyrinchus and shortnose Acipenser brevirostrum sturgeons acclimated to 15°C were determined using a heating rate of 8°C h?1. The critical thermal maximum averaged 30.8°C and 31.6°C for Atlantic and shortnose sturgeon, respectively, and values fell within the range noted for other sturgeon species. Oxygen‐carrying capacity (hemoglobin and hematocrit) measures were generally unaffected by thermal stress. Plasma lactate levels increased from 0.5 mm to 4 mm following temperature stress in both species. Both plasma glucose and potassium levels increased following CTmax, however, these levels were about double in the shortnose sturgeon. Lastly, plasma sodium and chloride levels were significantly depressed (by more than 10%) following thermal stress in shortnose sturgeon, whereas only chloride levels decreased in Atlantic sturgeon. Taken together, while CTmax values were similar, thermal stress resulted in different hematological profiles; these differences are consistent when compared to other stressors, and may be related to the phylogenetic position and thus could reflect the evolutionary history of these two species. 相似文献
30.
Clinkenbeard Erica L. Turpin Courtney Jiang Jieyun Peterson Martha L. Spear Brett T. 《Mammalian genome》2019,30(7-8):226-236
Mammalian Genome - BALB/cJ mice exhibit considerable phenotypic differences with other BALB/c substrains. Some of these traits involve the liver, including persistent postnatal expression of genes... 相似文献