全文获取类型
收费全文 | 266篇 |
免费 | 12篇 |
国内免费 | 1篇 |
出版年
2011年 | 7篇 |
2010年 | 8篇 |
2009年 | 14篇 |
2008年 | 7篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2002年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 7篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1971年 | 3篇 |
1969年 | 2篇 |
1958年 | 7篇 |
1957年 | 2篇 |
1956年 | 7篇 |
1955年 | 3篇 |
1954年 | 7篇 |
1953年 | 5篇 |
1952年 | 5篇 |
1951年 | 9篇 |
1950年 | 3篇 |
1949年 | 2篇 |
1948年 | 3篇 |
1947年 | 2篇 |
排序方式: 共有279条查询结果,搜索用时 78 毫秒
1.
2.
3.
4.
D. T. WILLIAMSON 《African Journal of Ecology》1991,29(2):105-117
Information on condition, growth and reproduction was collected from a sample of 155 female lechwe in the Linyanti Swamp, northern Botswana. Condition varied significantly with age, reproductive state and season and indications were found of relationships between body mass and the attainment of puberty in young females and body mass and the fertility of adult females. There were also indications that the population was under nutritional stress because of high water levels and that this had caused reductions in the growth rate and fertility of young females. It is suggested that the sensitivity of young females to adverse environmental conditions could be exploited to optimize population monitoring for conservation purposes by using them as an indicator class, rather than monitoring the entire population. Because of relationships between condition, growth and reproduction, it is also suggested that long-term monitoring of condition should form part of any effort to understand population dynamics. 相似文献
5.
Analysis of membrane proteins of Saccharomyces cerevisiae mitochondria in cycloheximide-inhibited cells shows that they are encoded on mitochondrial DNA. 相似文献
6.
KATHERINE M. G. ADAM D. A. BLEWETT W. G. FLAMM 《The Journal of eukaryotic microbiology》1969,16(1):6-12
SYNOPSIS. A method is described which permits the recovery of a high yield of undegraded DNA from Acanthamoeba castellanii. The DNA of A. castellanii is comprised of 2 species: the buoyant density of the major component is 1.720 and of the minor component, 1.693. The renaturation characteristics of the minor component suggest that it is of mitochondrial origin. Two components are also present in the DNA of A. palestinensis, A. polyphaga and A. astronyxis. The buoyant densities of major and minor components differ between species. 相似文献
7.
A Protein from Immature Raspberry Fruits which Inhibits Endopolygalacturonases from Botrytis cinerea and other Micro-organisms 总被引:2,自引:0,他引:2
A polygalacturonase-inhibiting protein (PGIP) was purified fromimmature raspberry fruits using ion exchange chromatography.The protein was composed of a single polypeptide chain withMr of 38·5 kDa and a pI residing above pH 10. Kineticstudies suggested that the inhibition was of a non-competitivenature. The PGIP inhibited two endopolygalacturonases (endo-PG)purified from Botrytis cinerea and an endo-PG produced by Aspergillusniger to varying degrees but did not inhibit two exo-PGs purifiedfrom B. cinerea, bacterial endopectate lyases and bacterialendo-PGs. The concentration of PGIP at various stages of flowerand fruit development was determined. The inhibitor was notdetected in the flower, but reached a maximum of 69 units g1in the immature green fruit decreasing to 9 units g1as fruits matured. The N-terminal amino-acid sequence was determined. Key words: Polygalacturonase-inhibiting protein, Rubus idaeus, red raspberry, Botrytis cinerea, pectinases 相似文献
8.
A. H. LINTON KATHERINE HOWE M. H. RICHMOND HELEN M. CLEMENTS A. D. OSBORNE BARBARA HANDLEY 《Journal of applied microbiology》1978,45(2):239-247
Attempts to limit the use of antibiotics have not, in general, resulted in the gut flora in farm animals becoming predominantly sensitive. Partial success has been demonstrated, however, by feeding chickens with antibiotic sensitive Escherichia coli known to be good colonizers of the chicken gut. Where feeding was done prior to slaughter a corresponding reduction in carcass contamination by resistant E. coli was observed. 相似文献
9.
A scoring technique is described for assessing midge blight using maps representing vascular lesions beneath periderm damaged by second generation larvae of Resseliella theobaldi . Individual canes were scored and some components of yield examined. Yield was not affected until lesions covered more than 20% of the stele surface at the base of canes. Midge blight scores increased with cane girth, probably because splitting of the cortex was most extensive in stout canes. 相似文献
10.
Two types of vascular lesion are described from the base of canes in plantations infested by raspberry cane midge ( Resseliella theobaldi ); (1) brown lobate lesions ('patches') confined to midge feeding areas, (2) brown lesions spreading proximally and distally from the point of infection ('stripes'). Either or both types of lesion may be presented in individual canes. Isolations from (1) produced principally Fusarium avenaceum ; isolations from tissues where (1) and (2) are contiguous gave Leptosphaeria coniothyrium and F. avenaceum ; isolations from (2) arising from old cane stub wounds in the absence of midge gave L. coniothyrium .
The important secondary role of fungi in the midge blight complex is confirmed, but the involvement of L. coniothyrium in the complex is unclear because it also infects stub wounds on midge-infested canes. 相似文献
The important secondary role of fungi in the midge blight complex is confirmed, but the involvement of L. coniothyrium in the complex is unclear because it also infects stub wounds on midge-infested canes. 相似文献