全文获取类型
收费全文 | 480篇 |
免费 | 30篇 |
国内免费 | 5篇 |
专业分类
林业 | 10篇 |
农学 | 1篇 |
34篇 | |
综合类 | 69篇 |
农作物 | 53篇 |
水产渔业 | 6篇 |
畜牧兽医 | 322篇 |
园艺 | 11篇 |
植物保护 | 9篇 |
出版年
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 31篇 |
2012年 | 16篇 |
2011年 | 15篇 |
2010年 | 19篇 |
2009年 | 8篇 |
2008年 | 21篇 |
2007年 | 23篇 |
2006年 | 22篇 |
2005年 | 17篇 |
2004年 | 8篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 14篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 4篇 |
1996年 | 5篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 11篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1972年 | 7篇 |
1971年 | 13篇 |
1970年 | 5篇 |
1969年 | 6篇 |
1968年 | 6篇 |
1967年 | 11篇 |
1966年 | 8篇 |
1965年 | 5篇 |
1964年 | 4篇 |
1961年 | 5篇 |
1952年 | 4篇 |
排序方式: 共有515条查询结果,搜索用时 15 毫秒
31.
J J De Castro A S Young R D Dransfield M P Cunningham T T Dolan 《Research in veterinary science》1985,39(3):279-288
Boran (Bos indicus) heifers were immunised by infection with local Theileria parva parva, T p lawrencei and T mutans stocks and treated with parvaquone and later exposed to natural tick and tick-borne disease challenge in the Trans-Mara Division of Kenya. The Theileria species parasites in the challenge were maintained in African buffalo and cattle and the tick vectors were supported by several species of wild Bovidae and domestic livestock present in the area. Thirty immune cattle were observed for 30 weeks while grazing on a ranch in the Trans-Mara Division. Of these, 15 were immersed in toxaphene at weekly or twice-weekly intervals while 15 cattle remained without acaricide application. Cattle which became pregnant were withdrawn from the experiment. There was no evidence of any clinical tick-borne disease in either group of cattle during the experiment. Five species of ixodid ticks infested the cattle during the experiment and cattle which were not treated with acaricide had far more ticks. Rhipicephalus appendiculatus was the most abundant tick species, with a mean infestation of 46 adults per animal in the undipped cattle. This tick also appeared to be the cause of the observed reduction in weight gains. Major haematological parameters did not differ significantly between the groups. Behavioural studies showed that the undipped cattle spent less time grazing and ruminating. This study has shown that, at the expense of some loss in productivity, zebu cattle, immunised against ticks and theileriosis, can be kept despite tick infestation. 相似文献
32.
Jessica A. Drake Timothy R. Cavagnaro Shaun C. Cunningham W. Roy Jackson Antonio F. Patti 《Land Degradation \u0026amp; Development》2016,27(1):52-59
Reforestation of saline sodic soil is increasingly undertaken as a means of reclaiming otherwise unproductive agricultural land. Currently, restoration of degraded land is limited to species with high tolerances of salinity. Biochar application has the potential to improve physical, biological and chemical properties of these soils to allow establishment of a wider range of plants. In a glasshouse trial, we applied biochar made from Acacia pycnantha (5 Mg ha−1) or no biochar to either a low (ECe 4·75 dS m−1, ESP 6·9), a moderate (ECe 27·6 dS m−1, ESP 29·3) or a high (ECe 49·4 dS m−1, ESP 45·1) saline sodic soil. The regional common reforestation species Eucalyptus viminalis and Acacia mearnsii were planted as tubestock in to the soils. Early establishment indicators, including growth, plant condition and nutrition, were assessed at the end of a simulated growing season, 108 days after biochar application. Application of biochar increased height, and decreased root : shoot and the concentration of Mn, N and S in plants of E. viminalis when grown in the highly saline sodic soil. Biochar application increased the concentration of B in leaves of E. viminalis and increased the concentration of P, K and S in leaves of A. mearnsii when grown in the low saline sodic soil. The results confirm that there is potential for biochar to assist in reforestation of saline sodic soils. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
33.
Constructed ponds are an important consideration in the conservation of wetland biota in agricultural landscapes. Twenty-two natural ponds and 22 adjacent constructed ponds (farm dams) were surveyed on the Southern Tablelands of New South Wales to compare patterns of use by frogs and develop frog conservation recommendations. Farm dams supported similar numbers of frog species to natural ponds, although differences in frog assemblage were observed between the pond types. Limnodynastes tasmaniensis and Uperolia laevigata were significantly more likely to occur at farm dams while L. peronii was more likely to occur at natural ponds. Results suggest waterbodies with high levels of emergent vegetation cover that lack fish are likely to support a high number of frog species, regardless of origin (i.e. natural or constructed). However, it is important for landholders to conserve natural waterbodies as these environments appear likely to support frog species that do not use farm dams. 相似文献
34.
35.
Cunningham B 《Science (New York, N.Y.)》1924,59(1537):536-537
36.
A critical step in the infectious cycle of Leishmania is the differentiation of parasites within the sand fly vector to the highly infective metacyclic promastigote stage. Here, we establish tetrahydrobiopterin (H4B) levels as an important factor controlling the extent of metacyclogenesis. H4B levels decline substantially during normal development, and genetic or nutritional manipulations showed that low H4B caused elevated metacyclogenesis. Mutants lacking pteridine reductase 1 (PTR1) had low levels of H4B, remained infectious to mice, and induced larger cutaneous lesions (hypervirulence). Thus, the control of pteridine metabolism has relevance to the mechanism of Leishmania differentiation and the limitation of virulence during evolution. 相似文献
37.
Myosin: a link between streptococci and heart 总被引:32,自引:0,他引:32
Murine monoclonal antibodies to Streptococcus pyogenes reacted with skeletal muscle myosin. High molecular weight proteins in extracts of human heart tissue that reacted with an antibody to S. pyogenes also reacted with a monoclonal antibody to ventricular myosin. Adsorption of the antibody to streptococci with S. pyogenes simultaneously removed reactivity of the antibody for either S. pyogenes or myosin. These results indicate that myosin shares immunodeterminants with a component of S. pyogenes. 相似文献
38.
Femtosecond laser pulses and coherent two-phonon Raman scattering were used to excite KTaO3 into a squeezed state, nearly periodic in time, in which the variance of the atomic displacements dips below the standard quantum limit for half of a cycle. This nonclassical state involves a continuum of transverse acoustic modes that leads to oscillations in the refractive index associated with the frequency of a van Hove singularity in the phonon density of states. 相似文献
39.
40.