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31.
Thirty cows naturally infected with Brucella abortus were treated by various routes, using free or liposomal streptomycin or a combination of liposomal streptomycin and a long-acting oxytetracycline preparation. Of 21 cows treated with liposomal streptomycin alone, 3 (14%) were culture negative and 3 had 10 or fewer bacterial colonies isolated from tissues obtained at necropsy. Thirteen (62%) cows continued to shed organisms in udder secretions and were considered treatment failures. Of 9 cows that were given a combination of liposomal streptomycin and long-acting oxytetracycline, 5 (56%) were cured, 3 had 10 or fewer colonies on culture plates of tissue after necropsy and only 1 continued to shed B abortus in udder secretions after treatment. Eleven cows were given streptomycin liposomes by intramammary infusion with or without IM administration of long-acting oxytetracycline. The most effective regimen consisted of 2 intramammary infusions of streptomycin liposomes and 2 doses of oxytetracycline administered IM. Of 5 cows treated thusly, 2 were cured and all others had fewer than 10 B abortus colonies isolated from tissues obtained at necropsy.  相似文献   
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A site suitability model of urban development was created for the Santa Monica Mountains in southern California, USA, to project to what degree future development might fragment the natural habitat. The purpose was to help prioritize land acquisition for the Santa Monica Mountains National Recreation Area and examine to what extent projected urban development would affect distinct vegetation classes. The model included both environmental constraints (slope angle), and spatial factors related to urban planning (proximity to roads and existing development, proposed development, and areas zoned for development). It implemented a stochastic component; areas projected to have high development potential in the suitability model were randomly selected for development. Ownership tracts were used as the spatial unit of development in order to give the model spatial realism and not arbitrarily `develop' grid cells. Using different assumptions and parameters, the model projected the pattern of development from 5 to 25 years hence (based on recent development rates in the area). While <25% of the remaining natural landscape is removed under these scenarios, up to 30% of core (interior) habitat area is lost and edge length between natural vegetation and development increases as much as 45%. Measures of landscape shape complexity increased with area developed and number of patches of natural habitat increased four- to nine-fold, depending upon model parameters. This increase in fragmentation occurs because of the existing patterns of land ownership, where private (`developable') land is interspersed with preserved park lands.  相似文献   
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OBJECTIVES: To compare virucidal effects and bone incorporation properties of cortical bone allografts transplanted into specific-pathogen-free (SPF) cats. Allografts consisted of untreated bone from a SPF cat (negative-control group) and bone from 5 FeLV-infected cats that was subjected to sterilization with ethylene oxide (ETO), preservation with glycerol, or no treatment (positive-control group). SAMPLE POPULATION: Bones from the aforementioned groups and twenty 8-week-old SPF cats (5 cats/group) implanted with an allograft from 1 of the aforementioned groups. PROCEDURE: After implantation, blood samples were collected weekly to monitor FeLV p27 antigen and antibody titers. Quantification of FeLV provirus was performed on blood samples at weeks 0, 4, and 8 and donor bone samples at time of implantation. Cats were euthanatized 8 weeks after transplantation, and graft sites were evaluated. RESULTS: All results for negative-control cats were negative. All ETO group cats had negative results for antigen and provirus in blood, whereas 1 cat had a low antibody titer. Although 3 ETO-treated allografts were positive for provirus, the DNA appeared denatured. One cat in the glycerol group had positive results for all tests in blood samples. All glycerol-preserved allografts were positive when tested for provirus. All results for positive-control group cats were positive. Differences in incorporation of bone grafts were not observed. CONCLUSIONS AND CLINICAL RELEVANCE: Glycerol preservation of FeLV-infected bone allografts did not eliminate transmission of retrovirus to recipients. In contrast, ETO sterilization appeared to denature DNA and prevent infection. Treatments did not affect incorporation of bone grafts in young cats.  相似文献   
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OBJECTIVE: To determine whether dietary antioxidants would attenuate exercise-induced increases in plasma creatine kinase (CK) activity in sled dogs. ANIMALS: 41 trained adult sled dogs. PROCEDURE: Dogs, randomly assigned to 2 groups, received the same base diet throughout the study. After 8 weeks on that diet, 1 group (21 dogs) received a daily supplement containing vitamins E (457 U) and C (706 mg) and beta-carotene (5.1 mg), and a control group (20 dogs) received a supplement containing minimal amounts of antioxidants. After 3 weeks, both groups performed identical endurance exercise on each of 3 days. Blood samples were collected before and 3 weeks after addition of supplements and after each day of exercise. Plasma was analyzed for vitamins E and C, retinol, uric acid, triglyceride, and cholesterol concentrations, total antioxidant status (TAS), and CK activity. RESULTS: Feeding supplements containing antioxidants caused a significant increase in vitamin E concentration but did not change retinol or vitamin C concentrations orTAS. Exercise caused significantly higher CK activity, but did not cause a significant difference in CK activity between groups. Exercise was associated with significantly lower vitamin E, retinol, and cholesterol concentrations and TAS but significantly higher vitamin C, triglyceride, and uric acid concentrations in both groups. CONCLUSIONS AND CLINICAL RELEVANCE: Use of supplements containing the doses of antioxidants used here failed to attenuate exercise-induced increases in CK activity. Muscle damage in sled dogs, as measured by plasma CK activity, may be caused by a mechanism other than oxidant stress.  相似文献   
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OBJECTIVE: To report clinical and serologic findings in horses with oral vesicular lesions that were consistent with vesicular stomatitis (VS) but apparently were not associated with VS virus (VSV) infection. DESIGN: Serial case study. ANIMALS: 8 horses. PROCEDURE: Horses were quarantined after appearance of oral lesions typical of VS. Severity of clinical signs was scored every 2 to 5 days for 3 months. Serum samples were tested for antibodies by use of competitive ELISA (cELISA), capture ELISA for IgM, serum neutralization, and complement fixation (CF). Virus isolation was attempted from swab specimens of active lesions. RESULTS: 2 horses with oral vesicular lesions on day 1 had antibodies (cELISA and CF) against VSV; however, results of CF were negative by day 19. Five of the 6 remaining horses were seronegative but developed oral lesions by day 23. Virus isolation was unsuccessful for all horses. CONCLUSIONS AND CLINICAL RELEVANCE: Horses were quarantined for 75 days in compliance with state and federal regulations. However, evidence suggests that oral lesions were apparently not associated with VSV infection. The occurrence in livestock of a vesicular disease that is not caused by VSV could confound efforts to improve control of VS in the United States and could impact foreign trade. Vesicular stomatitis is of substantial economic and regulatory concern.  相似文献   
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Cloning and expression of a Xenopus embryonic gap junction protein   总被引:26,自引:0,他引:26  
Gap junctions in the early amphibian embryo may play a fundamental role in the regulation of differentiation by mediating the cell-to-cell transfer of chemical signals. A complementary DNA encoding a gap junction present in Xenopus oocytes and early embryos has now been cloned and sequenced. This protein sequence is homologous to the well-characterized gap junction structural proteins rat connexin32 and connexin43. RNA blot analysis of total Xenopus oocyte RNA showed hybridization to a single 1.6-kilobase band. This messenger RNA is abundant in oocytes, decreases to levels below the sensitivity of our assay by stage 15 (18 hours), and is not detectable in RNA from a number of adult organs. To confirm that the oocyte cDNA encodes a gap junction channel, the protein was over expressed in Xenopus oocytes by injection of RNA synthesized in vitro. Pairs of RNA-injected oocytes formed many more time- and voltage-sensitive cell-cell channels than water-injected pairs.  相似文献   
40.
Routine blood smear findings in two of four 11‐day‐old mixed‐breed dog littermates were suggestive of a lysosomal storage disease (LSD) that was documented to be mucopolysaccharidosis type VII (MPS VII) by molecular testing. In this condition, a functional β‐glucuronidase deficiency results in the accumulation of glycosaminoglycans (GAGs) in cells and tissues where β‐glucuronidase is important in GAG degradation. Most neutrophils and a moderate number of lymphocytes within the blood had atypical cytoplasmic magenta inclusions. The bone marrow assessment from one of the two affected pups at 24 days of age revealed similar magenta granulation in myeloid precursor cells that was most prominent in promyelocytes and myelocytes. Moreover, atypical magenta material was present within vacuoles as well as extracellularly in some osteoblasts and macrophages. Histologic bone marrow sections revealed prominent vacuolation of osteoblasts, and some osteoclasts appeared separated from the bone by layers of osteoblasts or hematopoietic cells. At 2 months of age, the second affected dog showed moderate growth retardation and had similar but more prominent hematologic findings that extended to monocytes, eosinophils, and eosinophil precursors. It had an increased number of bone marrow macrophages with many vacuoles that could be seen cytologically to contain magenta material, and there was mild nonselective phagocytosis of hemic cells. Of the hematologic cells, inclusions were most prominent in promyelocytes, myelocytes, and macrophages, cells with relatively high β‐glucuronidase activity, and GAG exposure within lysosomes or lysosome‐like primary granules of granulocyte precursors.  相似文献   
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