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91.
Current status,opportunities, and challenges of cover cropping for sustainable dryland farming in the Southern Great Plains 总被引:1,自引:0,他引:1
Rajan Ghimire Binod Ghimire Abdel O. Mesbah Omololu John Idowu Michael K. O’Neill Sangamesh V. Angadi 《Journal of Crop Improvement》2018,32(4):579-598
Cropping systems that integrate cover crops into crop rotations, reduce tillage intensity and frequency, and maintain residue cover have the potential to improve agricultural sustainability in drylands. However, there is much yet to learn about the benefits of cover crops in sustainable dryland farming in the southern Great Plains (SGP). We reviewed the literature on the effects of cover crops on soil organic carbon (SOC), nitrogen, soil water conservation, and crop yields in dryland cropping systems of the US Great Plains (GP), and analyzed the opportunities and challenges for integrating cover crops into dryland crop-fallow systems of the SGP. Majority of the studies in the central Great Plains (CGP) and the northern Great Plains (NGP) of the United States suggest that cover cropping improves sustainability of cropping systems through their positive effects on SOC accumulation, nutrient cycling, soil erosion control, weed suppression, and soil health improvement. However, integrating cover crops into dryland cropping systems of the SGP faces challenges because of low quantity of soil-water availability. More research on the tradeoff between water use and other agroecosystem benefits of cover cropping is required to successfully integrate cover crops into dryland cropping systems in the SGP. 相似文献
92.
M. K. O’Neill C. C. Shock K. A. Lombard R. F. Heyduck E. B. G. Feibert D. Smeal R. N. Arnold 《Agroforestry Systems》2010,79(3):409-418
The rapid growth rates of hybrid poplar (Populus spp.) enable rotations of 3–6 years for biofuels or 10–15 years to obtain merchantable timber, but many clones are susceptible
to nutrient deficiencies when grown in alkaline soils. A 1995 Oregon study demonstrated that clone OP-367 (P. deltoides × P. nigra) was the only clone tested that performed well on alkaline soils. Tests in Colorado and New Mexico confirmed the adaptation
of this clone. A multi-clonal trial was established in 2003 at Farmington, New Mexico and Ontario, Oregon in order to screen
a larger number of clones for adaptability to alkaline soils. Trees were planted at 1.5 × 1.5 m spacing and irrigated by surface
drip irrigation. Diameter at breast height (DBH) and tree height were recorded annually (2003–2006); wood volumes (WVol) and
total aboveground biomass (TAB) were calculated from these measurements. Of the 25 clones tested, 19 were common to both sites.
Mean height was greater at the Ontario site through the first 3 years (2003–2005). By the end of four seasons, the tallest
Farmington entry was OP-367 at 9.4 m with 177 Mg ha−1 TAB while the tallest Ontario entry was Malheur-3 at 8.9 m with 195 Mg ha−1 TAB and several other clones had statistically similar production. Given the growth and productivity range at these two sites,
it is difficult to make generalizations across wide areas, but it appears feasible to identify clones suited to alkaline soils
in arid and semi-arid regions. 相似文献
93.
Julia F. Ridpath Paul Dominowski Ramasany Mannan Robert YanceyJr. James A. Jackson Lucas Taylor Sangita Mediratta Robert Eversole Charles D. Mackenzie John D. Neill 《Veterinary research communications》2010,34(8):691-702
Bovine viral diarrhea virus (BVDV) infections cause respiratory, reproductive, and enteric disease in cattle. Vaccination
raises herd resistance and limits the spread of BVDV among cattle. Both killed and modified live vaccines against BVDV are
available. While modified live vaccines elicit an immune response with a broader range and a longer duration of immunity,
killed vaccines are considered to be safer. One way to improve the performance of killed vaccines is to develop new adjuvants.
The goal of this research was evaluate new adjuvants, consisting of combinations of Quil A cholesterol and dimethyldioctadecylammonium
(DDA) bromide, for use in killed vaccines. Responses to three novel killed vaccines, using combinations of Quil A and DDA
as adjuvants, were compared to responses to a commercial modified live and a commercial killed vaccine. Vaccination response
was monitored by measuring viral neutralizing antibodies (VN) levels and by response to challenge. All three novel vaccines
were efficacious based on reduction in virus isolation, pyrexia, and depression. Compared to a commercial killed vaccine,
the three novel vaccines elicited higher VN levels and reduced injection site inflammation. 相似文献
94.
JB Siqueira RO Pinho SEF Guimarães T Miranda Neto JD Guimarães 《Reproduction in domestic animals》2010,45(6):1122-1125
This case study reported the presence of short tail sperm defect in the semen of three Nelore breed bulls. The sperm presented 0% of motility in the three animals evaluated and a total of 70%, 61% and 34% of pathologies of the intermediate piece of the tail respectively for animals 1, 2 and 3. It was identified that animals 2 and 3 had high degree of inbreeding, although no relationship was found with animal 1. Animal 2 was the only one that presented inbreeding coefficient (6.25%). His half‐sib (animal 3) and animal 1, from the same herd, had shown no inbreeding, showing that inheritance is not the only determinant factor for its incidence on Nelore males. 相似文献
95.
Neill G Barr 《Aquaculture Research》2012,43(3):438-446
Seawater sampling from three abalone farms in New Zealand showed average ambient concentrations of dissolved inorganic phosphate (Pi) varying between 2.36 and 238 μM. The Pi concentration within each system appeared to be directly linked to the percentage of water that was replaced each day. An experiment was conducted over 5 months to examine the effect of elevated Pi concentrations on the growth of two juvenile abalone (Haliotis iris) size classes (small: average shell length=23.9 ± 0.1 and large: average shell length=61.9 ± 0.1 mm). Abalone from each size class were exposed to Pi concentrations of; (a) natural incoming seawater (average 0.12 ± 0.12 μM), (b) 10.7 ± 1.3 μM, (c) 60.9 ± 5.8 μM and (d) 113.1 ± 5.6 μM. The results suggest that over the course of the 5‐month period of this experiment there was a significant negative impact on growth (shell length and wet weight) when the smaller size class of abalone were exposed to Pi concentrations greater than 10.7 μM and for the large size class of abalone when exposed to greater than 60.9 μM Pi. However, elevated Pi concentrations did not significantly impact on abalone survival during the course of the experiment. 相似文献
96.
Mycobacterium bovis was isolated from the respiratory tracts of three cattle which registered negative to tuberculin testing; no tuberculous lesions were found and the culture of lymph nodes and other tissues proved negative. One animal was from a group of five calves which had been inoculated intranasally with M bovis, and the organism was recovered once only from nasal mucus sampled 100 days after inoculation. The second animal had had contact with experimentally infected cattle which were excreting M bovis and the third was from a commercial farm. The results of ELISAS for antimycobacterial antibodies and interferon-gamma, and of lymphocyte transformation assays are presented. The animals' immune responses provided evidence that each of them had been challenged. 相似文献
97.
Twenty-five of 50 randomly selected tuberculin-reacting cattle were confirmed as tuberculous in the laboratory. All 25 cattle had macroscopic lesions in lymph nodes associated with the respiratory tracts but only one had lung lesions. M bovis was isolated from the anterior respiratory tracts in the heads of four of the 25 tuberculous animals and from a nostril lesion found in a fifth. For at least three of these five animals, the intervals between the final tuberculin test and their previously negative tests indicated that infection had established relatively rapidly. Four of them had been tuberculin tested solely because they were animals in contiguous 'at risk' herds. It would appear that although M bovis can be isolated from the anterior respiratory tracts in the heads of tuberculin-reacting cattle, it is unlikely that primary foci of infection exist in regions other than the lungs or associated tissues. The study demonstrates the potential for reactors with lesions to excrete M bovis and the continued importance of infected cattle in the epidemiology and eradication of the disease. 相似文献
98.
The metabolism and conjugation of 3-phenoxybenzyl alcohol, a plant metabolite of permethrin and cypermethrin, have been examined in abscised cotton leaves. Mature cotton leaves were treated by petiole uptake of an aqueous solution of [α-14C]-3-phenoxybenzyl alcohol. Initially there was rapid formation of a compound identified as the glucosyl 3-phenoxybenzyl ether. Subsequently more polar compounds were formed and these were shown to be disaccharide conjugates of the alcohol with glucose and pentose sugars. The alcohol and its mono- and disaccharide conjugates were shown to undergo interconversion in cotton leaves, and evidence was obtained from experiments with [14C]glucose for the ready exchange of the glucose units on the conjugates with free glucose in the leaves. No larger carbohydrate conjugates of 3-phenoxybenzyl alcohol were detected under the conditions used. 相似文献
99.
100.
Animal welfare is expected to increase in importance as a political and marketing issue. There is a vigorous debate about what, besides the absence of physical pain, is necessary for acceptable animal welfare. This paper focuses on the present state of animal welfare policy at the national level. 相似文献