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61.
A screen house experiment was undertaken to study effect of time of application of deoiled castor cake on the yield, N and P uptake by wheat crop. The results indicate that the wheat growth decreased significantly with increasing dose of castor cake, when castor cake was applied just before sowing of wheat. When castor cake was applied 10 days before wheat sowing, the dry matter yield (DMY) of wheat increased up to 0.125% dose of castor cake and reduced thereafter. But when the castor cake was applied 20 days before wheat sowing, the DMY was at par under all the doses of castor cake and better than control indicating the degradation of the toxicants produced by the castor cake. Application of castor cake can also be helpful in reducing the cost of phosphatic fertilizer. Thus it can be concluded that castor cake should be applied at least 3 weeks before sowing of the crop and keeping the field moist for degradation of the toxicants.  相似文献   
62.
Neotyphodium coenophialum, (Morgan‐Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non‐infected isolines on phosphorus (P)‐deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E‐) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg‐1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high specificity of endophyte‐tall fescue associations. Endophyte infection did not affect root dry matter (DM) when no P was supplied but shoot DM was reduced by 20%. More biomass was produced and greater P uptake rate occurred in PR than PF treatment. Root DM was greater in E+ DN4 than E‐DN4 when supplied with either PF or PR. In contrast, endophyte infection did not affect root DM of DN2, regardless of P source. Relative growth rate (RGR) of E+ plants grown with PR was 16% greater than that of E‐plants. Endophyte infection did not improve growth or P uptake in PF treatment. When PR was supplied, P uptake rate was 24% greater in E+ DN2 than E‐ DN2, but endophyte infection did not benefit DN4. Phosphorus‐use efficiency was 6% less in E+ DN2 but 16% greater in E+ DN4 compared to E‐ plants, regardless of P source. Root exudates of E+ DN2, but not E+ DN4 solubilized more P from PR than those of E‐ plants. The correlation between root RGR and P uptake rate was relatively high for E‐ plants (r=0.76), but low for E+ plants (r=0.27) grown with PR. Results suggest that P uptake by E+ tall fescue might rely on mechanisms other than an increase in root biomass (surface area). Endophyte infection modified tall fescue responses to P source. This phenomenon was associated with modes of P acquisition which included enhanced activity of root exudates in releasing P from PR in E+ plants (DN2), and increased root biomass (DN4). The dominant means of P acquisition may be determined by a specific association of endophyte and tall fescue genomes. Endophyte‐tall fescue association plasticity contributes to widespread success of symbiotic in marginal resource conditions.  相似文献   
63.
Objective To investigate the efficacy of ivermectin in an intraruminal controlled-release capsule (CRC) against blowfly strike.
Design Pen and field trials with controls.
Animals Pen studies: Two breech strike trials involving 60 Romney and 60 Merino sheep. One body strike trial using 100 Merino sheep.
Field trials: Eight trials in New Zealand used 1000 Romney and Romney-cross sheep. Fifty Merino lambs in one trial in Australia.
Procedure Pen studies: Sheep were allocated to two equal groups. One was not treated, the other sheep received a CRC that delivered ivermectin at 20 μg/kg/day for 100 days. In the breech strike trials, each animal was given an oral laxative 2 days before exposure to adult Lucilia cuprina . In the body-strike trial, the sheep sheep were kept wet to increase susceptibility prior to the release of blowflies.
Field trials: Fifty or 200 sheep allocated to equal groups of nontreated or treated with the CRC and grazed at pasture exposed to natural blowfly challenge.
Results Pen studies: Breech strikes developed in 24 of 60 controls but in none of 60 CRC-treated sheep. There was a 35% reduction in the number of CRC-treated sheep struck on the body.
Field trials: The average number of breech strikes in CRC-treated sheep was reduced by 86% (P < 0.001). The number of body strikes in the treated groups was a reduced by 27% (P < 0.05).
Conclusion The ivermectin CRC is a useful aid in controlling breech strike, but provides only moderate reduction in the incidence of body strike.  相似文献   
64.
Objective To confirm the efficacy of ivermectin released from a controlled-release capsule administered to young sheep and to breeding ewes under field conditions. Design Randomised field trials. Procedure In each of ten field trials 25 weaned lambs were treated with ivermectin controlled-release capsules and 25 remained untreated. Eight similar field trials were conducted using adult ewes. Efficacy against infections of gastrointestinal nematodes was assessed by faecal egg counts and faecal larval culture. Body weights were recorded and faecal soiling of the breech wool (dags) was assessed. Results Nematode faecal egg counts in the two groups were not different (P = 0.13) before treatment in the weaner trials or before treatment in the ewe trials (P = 0.49), but thereafter eggs in the untreated sheep persisted, whereas counts in sheep given capsules were negligible (P ≤ 0.01). In the weaner trials, dag scores for the two groups were not different at the start of the trials (P = 0.18) but at the end, untreated sheep had significantly more dags (P = 0.04) than treated sheep. In the ewe trials, dag scores remained low in both groups. Weaners treated with the capsule gained 1.4 kg (95% CL: 0.7, 3.1) more weight over the 16 week trial period compared to untreated weaners (P = 0.01). Both groups of ewes lost weight as a result of parturition but the mean loss by week 16 was greater for untreated (3.7 kg) (95% CL: -5.1,-2.2) than for treated ewes (1.8 kg) (95% CL: -3.3, -0.4). The mean change in ewe body weight for the two groups was however not significant (P = 0.07). Differentiation of nematode larvae recovered from cultures of faeces from untreated animals indicated that the capsules were effective against the common parasites of sheep. Conclusion The capsule was efficacious against gastrointestinal nematodes judging from faecal egg counts. It has the potential to significantly reduce contamination of pasture with nematode eggs. Treated weaners had less dags for 16 weeks and gained more weight than untreated weaners.  相似文献   
65.
Mechanisms involved in mineral stress tolerance of cool-season grasses infected by Neotyphodium spp. endophytes are not known. In a controlled-environment experiment, two genotypes (DN2 and DN4) of tall fescue ( Festuca arundinacea Schreb.) infected (E+) with their naturally occurring strains of N. coenophialum (Morgan-Jones and Gams) Glenn, Bacon and Hanlin, and their non-infected (E−) isolines were cultivated in nutrient solution at two phosphorus (P) levels of 31 mg P dm−3 (P+) and 0.31 mg P dm−3 (P−) for 3 weeks. Diameters of lateral roots, root hair length, and distance between root hairs were recorded using a digital image analysis system (Dage 72S CCD camera controlled by a Power MacIntosh 7200/120PC compatible computer equipped with an AG-5 frame grabber board and NIH-Image). Irrespective of tall fescue genotype and P level in nutrient solution, E+ plants had roots with a smaller diameter (16 %) than E− plants. In response to P deficiency, root diameter of E+ plants declined by 11 % and root hair length increased by 17 % when compared to E− plants. Altered root diameter and root hair length might be one of the mineral stress tolerance mechanisms in endophyte-infected tall fescue.  相似文献   
66.
Among the factors that affect the efficiency of somatic cell nuclear transfer (SCNT) in pigs, the activation protocol is the most variable among the current SCNT procedures. The aim of this study is focused on defining an efficient activation treatment of porcine oocytes. In Experiment 1, we studied the effects of nine different oocyte activation procedures (including chemical‐ and electrical‐based treatments) on parthenogenetic embryo development. In Experiment 2, we studied the effect of the more efficient activation procedures on the gene expression profile of Oct4 and Igf2r in parthenogenetic blastocysts. In conclusion, ionomycin as a first calcium stimulus is not able to activate porcine oocytes efficiently in comparison with electric procedures. Electrical treatments with 6‐DMAP significantly increased the level of Oct4 expression, whereas the single and double pulse treatments alone maintained the same profile as the IVF group.  相似文献   
67.
Cool-season grasses infected with Neotyphodium endophytes may be more persistent and competitive than non-infected plants. In a greenhouse experiment, two tall fescue ( Festuca arundinacea Schreb.) cloned genotypes (DN2 and DN11) with different growth characteristics and endophyte status (E−, non-infected; E+, infected) were grown in monocultures and in full competition with red clover ( Trifolium pratense L.) cv. Reddy Red for 20 weeks. When grown in monoculture, endophyte infection reduced the root dry matter (DM) of DN2 (16 %) and DN11 (5 %) when compared to E− plants, while shoot DM was not affected. In full competition with red clover, root and shoot DM of tall fescue were not influenced by endophytes, but cumulative herbage DM yield was less in E+ than in E− plants. Root growth of red clover was significantly depressed (22 %) in competition with E+ plants of DN2 compared to E− plants, but was not affected when plants were grown in competition with DN11. The relative yield total (RYT) did not differ from 1.0 in red clover mixtures with E− plants of DN2 and DN11, and with E+ plants of DN11, indicating competition between the competitors for the same resources. In contrast, RYT was less than 1.0 in the red clover/DN2 E+ mixture, suggesting a negative interaction between the competitors. Endophyte infection increased the competitive ability of DN2 but reduced that of DN11 when compared to E− plants. Because the concentration of pyrrolizidine alkaloids in roots of E+ plants of DN2 was twice that found in roots of DN11 (1083 and 536 μg g−1, respectively), we suggest that pyrrolizidine alkaloids might influence the competitive ability of some endophyte–tall fescue associations through a possible allelopathic effect on companion species.  相似文献   
68.
Antibiotics are widely used in treatment and prophylaxis of mastitis, but their antibacterial and therapeutic efficacy continues to decrease. New methods of prophylaxis of mastitis with the use of vaccines and biological response modifiers are reviewed. Prophylactic activity of staphylococcal vaccines should be investigated in the future because of difficulties in successful treatment of infections caused by these organisms. Vaccination with J5 bacterin (0111:B4) reduced duration of IMI and local signs of clinical coliform-mastitis. Some immunomodulators proved to be effective in treatment of mastitis during lactating period. Promising results were obtained with the use of giseng saponin, herbal gel, herbal extracts, propolis, lysosubtilin, antibacterial proteins, and lysozyme dimer especially.  相似文献   
69.
Although ordinary chondrite (OC) meteorites dominate observed falls, the identification of near-Earth and main-belt asteroid sources has remained elusive. Telescopic measurements of 35 near-Earth asteroids ( approximately3 kilometers in diameter) revealed six that have visible wavelength spectra similar to laboratory spectra of OC meteorites. Near-Earth asteroids were found to have spectral properties that span the range between the previously separated domains of OC meteorites and the most common (S class) asteroids, suggesting a link. This range of spectral properties could arise through a diversity of mineralogies and regolith particle sizes, as well as through a time-dependent surface weathering process.  相似文献   
70.
Plasma concentrations of adiponectin and leptin were measured in 23 mature Standardbred mares (age: 10 ± 3 years) and 12 weanling fillies (10 Quarter Horse/Belgian crossbreds and two Quarter Horses; aged: 4 ± 3 months) to test the hypothesis that adipocytokines are proportional to adiposity in horses. Rump fat thickness was measured using B-mode ultrasound and percent body fat (% fat) calculated using a published formula for the estimation of fatness in horses. Plasma adiponectin and leptin were determined using radioimmunoassay. In the absence of purified equine adiponectin or leptin, results were expressed as human equivalents (HE) of immunoreactive (ir) adipocytokines.Plasma ir-leptin HE concentration was positively correlated (r = 0.543; P < 0.001) with percent body fat and (r = 0.556; P < 0.001) to fat mass in all horses. The plasma ir-leptin HE concentration was lower (P = 0.03) in weanlings (1.90 ± 0.34 ng/mL HE) than in mature mares (3.47 ± 0.50 ng/mL HE). The ratio of ir-adiponectin HE to ir-leptin HE was negatively correlated (r = −0.621; P < 0.001) to percent fat and (r = −631; P < 0.001) to fat mass in all horses. The ratio of ir-adiponectin HE to ir-leptin HE was higher (P < 0.001) in weanlings (3.04 ± 0.51) than mature mares (1.03 ± 0.13). These data suggest that leptin is proportional while adiponectin is inversely proportional to adiposity in horses.  相似文献   
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