全文获取类型
收费全文 | 467篇 |
免费 | 1篇 |
专业分类
林业 | 9篇 |
农学 | 8篇 |
43篇 | |
综合类 | 58篇 |
农作物 | 8篇 |
水产渔业 | 56篇 |
畜牧兽医 | 209篇 |
植物保护 | 77篇 |
出版年
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 17篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2002年 | 4篇 |
1999年 | 4篇 |
1998年 | 9篇 |
1997年 | 14篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 13篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 20篇 |
1990年 | 7篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1965年 | 3篇 |
1963年 | 5篇 |
1961年 | 3篇 |
1960年 | 5篇 |
1959年 | 9篇 |
1958年 | 18篇 |
1957年 | 11篇 |
1956年 | 14篇 |
1955年 | 6篇 |
1954年 | 9篇 |
1953年 | 7篇 |
1946年 | 7篇 |
排序方式: 共有468条查询结果,搜索用时 8 毫秒
81.
82.
83.
84.
85.
86.
87.
Colostrum-deprived, colostrum-fed or suckling foals were orally inoculated with foal rotavirus and enterotoxigenic Escherichia coli derived from a calf. Neither agent given alone caused diarrhoea in foals aged 1 or 2 days, although with rotavirus, 2 of the 3 inoculated foals became depressed 3 days after inoculation and all 3 were excreting rotavirus in the faeces. Inoculation of both agents induced diarrhoea in colostrum-deprived, colostrum-fed or suckling foals aged up to 16 days. There was an apparent age-related resistance to diarrhoea which developed between 2 and 3 weeks of age. It was related to failure of rotavirus to establish apparent infection in older foals and was independent of preinoculation maternal antibody. 相似文献
88.
Analysis of the results of 104 personnel who determined the particle size distribution of 16 different soil-size materials indicated that there was an effect of subsample preparation. Subsamples prepared using a chute splitter tended to be coarser than those prepared by coning and channelling. This effect was observed for material retained on 425 μm and 75 μm sieves from a variety of soil types. The results confirm those obtained on artificially prepared mixes. The conclusion is that the chute splitter is a more reliable method for obtaining the test portion than coning and channelling. 相似文献
89.
Large undisturbed soil cores (20 cm diam. × 25–30 cm long) were irrigated at rates of 0.5–4 cm h?1 with 0.005 M CaCl2 solution labelled with 3HOH. The cores were used at varying initial water contents and flow in all cases was unsaturated. Breakthrough curves for Cl and 3HOH were markedly asymmetric and unlike those reported for columns of packed aggregates. The data could be satisfactorily described using a density distribution function of the logarithm of cumulative drainage D. The mean and standard deviation of In D were estimated by a curve-fitting procedure from Cl and 3HOH effluent concentrations in each core. The mean pore water velocity and fraction of the soil water that participated in solute transport (the mobile volume) were also calculated. The apparent velocity of Cl movement was always greater than that of 3HOH which suggested that the mobile volume involved in convective and diffusive transport of Cl was less than that for 3HOH. We suggest that Cl and 3HOH diffused at different rates out of flowing water films in a relatively few large conducting channels into essentially immobile water within the surrounding soil matrix. The difference in mobile volume for Cl and 3HOH was used to calculate the perimeter of voids in any horizontal cross-section of the soil through which water flowed, assuming a planar interface between the mobile and immobile water. 相似文献
90.
ALLAN E. SMITH 《Weed Research》1984,24(4):291-295
The persistence of bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), [14C]dicamba (3,6-dichloro-2-methoxybenzoic-7-14C acid) and propanil [N-(3,4-dichlorophenyl)propionamide] at rates equivalent to 1 kg ha?1, were studied under laboratory conditions in a clay loam, a heavy clay and a sandy loam at 85% of field capacity and at 20±1°C, both singly and in the presence of herbicides normally applied with these chemicals as tank-mix or split-mix components. The degradation of bromoxynil was rapid with over 90% breakdown occurring within a week in the heavy clay and sandy-loam soils, while in the clay-loam approximately 80% of the bromoxynil had broken down after 7 days. In all three soils degradation was unaffected by the presence of asulam, diclofop-methyl, flamprop-methyl, MCPA, metribuzin or propanil. Propanil underwent rapid degradation in all soil treatments, with over 95% of the applied propanil being dissipated within 7 days. There were no noticeable effects on propanil degradation resulting from applications of asulam, barban, bromoxynil, dicamba, MCPA, MCPB, metribuzin or 2,4-D. The breakdown of [14C]dicamba in a particular soil was unaffected by being applied alone or in the presence of diclofop-methyl, flampropmethyl, MCPA, metribuzin, propanil or 2,4-D. The times for 50% of the applied dicamba to be degraded were approximately 16 days in both the clay loam and sandy loam, and about 50 days in the heavy clay. 相似文献