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31.
丘陵地土壤侵蚀被普遍认为是菲律宾国内最严重的环境问题 ,影响到了土地总面积的 6 3%~ 76 % (Paningbatan ,1 990 )。近 2 0年来 ,政府和非政府组织已经实施了丘陵地发展项目 ,其中的一个主要组成部分就是改进丘陵地农民使用的土壤保持措施 (如丘陵地农业技术或S 相似文献
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Temperini Carolina Virginia Tudela Marisa Andrea Aluminé Gimenez Gustavo Nestor Di Masi Susana Noemí Pardo Alejandro Guillermo Pose Graciela Noemí 《European journal of plant pathology / European Foundation for Plant Pathology》2022,163(3):529-544
European Journal of Plant Pathology - Recently, a new plant disease was detected in the rural area of the High Valley of Río Negro, in Northern Patagonia, Argentina, called “Brown Spot... 相似文献
34.
FA Street-Perrott Y Huang RA Perrott G Eglinton P Barker LB Khelifa DD Harkness DO Olago 《Science (New York, N.Y.)》1997,278(5342):1422-1426
Carbon-isotope values of bulk organic matter from high-altitude lakes on Mount Kenya and Mount Elgon, East Africa, were 10 to 14 per mil higher during glacial times than they are today. Compound-specific isotope analyses of leaf waxes and algal biomarkers show that organisms possessing CO2-concentrating mechanisms, including C4 grasses and freshwater algae, were primarily responsible for this large increase. Carbon limitation due to lower ambient CO2 partial pressures had a significant impact on the distribution of forest on the tropical mountains, in addition to climate. Hence, tree line elevation should not be used to infer palaeotemperatures. 相似文献
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One hundred ninety-six male and female turkeys representing two genetic lines were experimentally infected with Bordetella avium. The lines of turkeys included a randombred control line (RBC2) and a subline (F) of RBC2 selected for increased 16-wk body weight. No difference was found between lines RBC2 and F in the number of days to onset of clinical signs, and no mortality due to B. avium infection was observed in either line. Interestingly, however, a significant depression (12%) occurred in body weight of F line poults infected with B. avium, but no significant depression occurred in body weight of RBC2 poults. 相似文献
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Ortega C Parilla G De Balogh K De Rosa M Gimeno O Estol L Dobosh D Leguia G Falcon N Fonseca A Torres M Caballero M Quiros J Vilhena MC Villamil LC Cediel N De Meneghi D 《Journal of veterinary medical education》2007,34(4):492-496
Continued contact between humans and animals, in combination with the ever-increasing movement of human and animal populations that is one effect of globalization, contributes to the spread of diseases, often with detrimental effects on public health. This has led professionals involved in both animal health and public health to recognize veterinary public health (VPH) as a key area for their activities to address the human-animal interface. Veterinarians, a profession with major involvement in this field, are in need of specific knowledge and skills to prevent and control public-health problems. As a result, VPH must be directly integrated into veterinary educational programs. At present, only few veterinary schools have specific VPH programs; in most institutions, VPH does not feature as a specific subject in either undergraduate or post-graduate curricula. SAPUVET and SAPUVETNET II are network projects supported by the ALFA program of the European Union (EU). Their main objectives are to reach a common understanding between European and Latin American universities in the definition of the areas in which VPH is important in their respective countries, and to design a harmonized training program for veterinarians in VPH, by making use of new technological applications and innovative teaching methodologies. The elaboration of educational material in combination with case studies presenting real-life problems provides a basis to apply the knowledge acquired on VPH. It is envisaged that the material and modules developed during the two projects will be integrated into the veterinary curricula of the participating universities, as well as in other partner organizations. 相似文献
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The potential contribution of agroforestry systems to the management and genetic resources conservation in iroko (Milicia excelsa), an important and valuable timber tree species in sub-Saharan Africa, is addressed in this paper. The structure and dynamics
of traditional agroforestry systems and the ecological structure of Milicia excelsa populations in farmlands were studied through a survey carried out in 100 farmlands covering the natural range of iroko in
Benin. Forty-five species belonging to 24 plant families were recorded in traditional agroforestry systems. Average tree density
varied from 1 to 7 stems ha−1 with diversity index ranging from 2.6 to 2.9. Milicia excelsa occurred sparsely in agroforestry systems in all regions, with density ranging from 1 to 4 stems ha−1; stand basal area varying from 33.10−4 to 129.10−4 m2 ha−1, and negligible seedling regeneration. However, male and female trees were apparently evenly distributed on farmlands in
all regions (F/M > 0). Iroko trees produced viable seeds with moderate germination rate and early growth (germination rate
22% and height 7.29 cm after 3 months). Suggestions are made regarding optimal densities for iroko conservation in farmlands,
according to farmers’ socioeconomic conditions in different regions, in order to improve traditional agroforestry systems
and their use as biological corridors in conservation of Milicia excelsa genetic resources. 相似文献
40.
Earthquakes on dipping faults: the effects of broken symmetry 总被引:3,自引:0,他引:3
Dynamic simulations of earthquakes on dipping faults show asymmetric near-source ground motion caused by the asymmetric geometry of such faults. The ground motion from a thrust or reverse fault is larger than that of a normal fault by a factor of 2 or more, given identical initial stress magnitudes. The motion of the hanging wall is larger than that of the footwall in both thrust (reverse) and normal earthquakes. The asymmetry between normal and thrust (reverse) faults results from time-dependent normal stress caused by the interaction of the earthquake-generated stress field with Earth's free surface. The asymmetry between hanging wall and footwall results from the asymmetric mass and geometry on the two sides of the fault. 相似文献