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61.
The objective of the present study was to quantify the effect of strain of Holstein–Friesian and pasture-based feeding system on calving performance, blood parameters and overall survival within a seasonal calving milk production system. The three strains of Holstein–Friesian compared were high production North American (HP), selected entirely for milk production, high durability North American (HD), selected based on milk production, fertility and muscularity traits, and New Zealand (NZ) selected from a seasonal calving pasture-based system. The three feed systems compared were a high grass allowance feed system typical of spring calving herds in Ireland (MP; control); an increased stocking rate system (HS) and an increased concentrate supplementation system (HC). Data comprised up to 585 lactations on 240 cows. Data were analysed using linear mixed models, generalised estimating equations and survival analysis. Strain of Holstein–Friesian had no significant effect on calving difficulty or rate of stillbirths while the effect of feed system on calving difficulty and rate of stillbirths approached significance. Strain of Holstein–Friesian had no significant effect on plasma metabolite or hormone concentrations around parturition, with the exception of urea concentration. At the beginning of the breeding season the NZ strain had lower plasma concentrations of NEFA (0.20 mmol/l) and higher IGF-I (86.8 ng/ml) than the HD (0.24 mmol/l and 66.9 ng/ml, respectively) and HP (0.26 mmol/l and 64.0 ng/ml, respectively) strains. The higher IGF-I concentration of the NZ strain was maintained during the breeding season. The NZ and HD strains survived longer than the HP strain with median survival days post-first calving of 1372, 1367 and 1033 respectively, while feed system had no significant effect on overall survival rate over the study period.  相似文献   
62.
Foot-and-mouth disease virus (FMDV) spreads by direct contact between animals, by animal products (milk, meat and semen), by mechanical transfer on people or fomites and by the airborne route, with the relative importance of each mechanism depending on the particular outbreak characteristics. Atmospheric dispersion models have been developed to assess airborne spread of FMDV in a number of countries, including the UK, Denmark, Australia, New Zealand, USA and Canada. These models were compared at a Workshop hosted by the Institute for Animal Health/Met Office in 2008. Each modeller was provided with data relating to the 1967 outbreak of FMD in Hampshire, UK, and asked to predict the spread of FMDV by the airborne route.A number of key issues emerged from the Workshop and subsequent modelling work: (1) in general all models predicted similar directions for livestock at risk, with much of the remaining differences strongly related to differences in the meteorological data used; (2) determination of an accurate sequence of events on the infected premises is highly important, especially if the meteorological conditions vary substantially during the virus emission period; (3) differences in assumptions made about virus release, environmental fate and susceptibility to airborne infection can substantially modify the size and location of the downwind risk area. All of the atmospheric dispersion models compared at the Workshop can be used to assess windborne spread of FMDV and provide scientific advice to those responsible for making control and eradication decisions in the event of an outbreak of disease.  相似文献   
63.
This study presents clinical findings after oral ingestion of Toxocara cati eggs which resulted in rapid pulmonary lung migration and parenchymal disease, noted on clinically relevant diagnostic methods. Further, the study investigated the efficacy of pre-infection applications of preventative medication on larval migration through the lungs. A third aim of the study was to determine if adult cats infected with T. cati developed lung disease. Cats in infected groups were administered five oral doses of L3 T. cati larvae. Four-month-old specific pathogen free (SPF) kittens were divided into three groups (six per group): an infected untreated group, an uninfected untreated control group, and an infected treated group (topical moxidectin and imidacloprid, Advantage Multi for Cats, Bayer Healthcare LLC). Six 2- to 3-year-old adult multiparous female SPF cats were an infected untreated adult group. The cats were evaluated by serial CBCs, bronchial–alveolar lavage (BAL), fecal examinations, thoracic radiographs, and thoracic computed tomography (CT) scans and were euthanized 65 days after the initial infection.  相似文献   
64.
65.
A rapid laser scanning system was developed to map the spread of excitation in amphibian and mammalian hearts stained with fluorescent dye. Isochronic maps of conduction were constructed by timing the upstroke of the optical action potential; 128 sites could be scanned in 4 milliseconds. The accuracy of this technique was verified by recording simultaneously from 16 unipolar electrodes placed in different areas of the heart. Conducted action potentials in normal frog heart propagated at 0.1 meter per second. Propagation of action potentials was also monitored in ischemic cat heart, in which both driven and arrhythmic action potential upstrokes could be tracked. The results suggest that this system is capable of scanning the normal and abnormal spread of electrical activity in the heart.  相似文献   
66.
ABSTRACT

In the allocation of collection resources, it is important to have a good understanding of the teaching, instruction and research needs of faculty and graduate students. Data related to the use of electronic databases, journals, books, etc. is helpful; however, this data does not reflect the nature and impact of the information retrieved, but merely provides a general idea of the number of times items have been searched, retrieved or borrowed. By identifying and analyzing faculty and graduate students' publications and grant proposals to determine where researchers are publishing and what sources they are citing in their research, the Library can assess how well it is supplying a core of literature to meet research needs. To this end, this study analyzes the publication and citation patterns of food science faculty at the University of Arkansas for a fourteen-year period, 1990–2003. The findings show that faculty are using and citing materials ranging from 1 to 22 years old and that 85 titles account for only 13.67% of the total journals cited but for 77.75% of the citations. It is assumed that these 85 titles constitute the core journal titles for food science research.  相似文献   
67.
S. Dillon  C. Ramage  R. Drew  S. Ashmore 《Euphytica》2005,145(1-2):11-23
Papaya ringspot virus type P (PRSV-P) is a significant disease of Carica papaya. A major gene for PRSV-P resistance has been mapped in Vasconcellea cundinamarcensis, a distant relative of C. papaya. This was achieved by genetic mapping of the resistance phenotype and inherited, dominant, polymorphic randomly amplified DNA fingerprint (RAF) markers in F2 progenies of V. parviflora and V. cundinamarcensis. The parents of this cross confer resistance to several major diseases that affect C. papaya including PRSV-P in V. cundinamarcensis. Heredity of DNA markers and PRSV-P resistance was studied in the intrageneric population presented due to intergeneric fertility barriers between Carica and Vasconcellea. Genetic polymorphism between parents, based on RAF markers, was 75% with more than 70% of markers generated showing mendelian segregation for the expected ratios 1:3 or 1:1 (p < 0.05). Preferential inheritance of markers from either parent was not detected in the F2, indicating stable transfer of the genetic material. Discrete V. parviflora and V. cundinamarcensis linkage maps were compiled from 79 and 83 framework markers, delineating to 10 and 11 groups respectively. F1 and F2 progeny were screened for resistance to PRSV-P under controlled conditions. The resistant phenotype segregated 3:1 in the F2 and mapped to V. cundinamarcensis linkage group 7 with adjacent RAF markers within 4 cM. The framework maps of V. parviflora and V. cundinamarcensis presented cover 630.2 and 745.4 cM respectively, accounting for between 47–52 and 49–55 percent of the predicted genome lengths. These maps provide a platform for further genetic study of disease resistance characteristics identified in these species and the development of DNA markers tightly linked to these traits, which could be applied to the breeding of resistant C. papaya cultivars.  相似文献   
68.
Using a nationally representative survey of farm operators in Ireland, this study examines the effect of non-pecuniary benefits from farm work on labor allocation choices. Results suggest that non-pecuniary benefits affect both the decision to enter the off-farm labor market and also once that decision is made, the amount of time spent working off-farm. We find our derived variable representing non-monetary benefits associated with farm work to have a substantial impact similar to the effect of other more widely reported personal and farm structural variables such as the age of the farm operator, farm size, and farming system. The existence of these non-pecuniary benefits serves to increase the implied wage to farmers for their farm work. This in turn can lead to allocations of labor that would seem suboptimal from a purely financial point of view. Rural development policies aimed at creating off-farm opportunities could fail unless returns to off-farm work are high enough to compensate the farmer for losing the benefits associated with the farming lifestyle. From a methodological perspective, our analysis indicates that failure to model off-farm labor allocation choices as a two-part process may lead to some incorrect conclusions regarding the effect of certain explanatory variables. Outside of explaining farmers’ off-farm labor supply it would be useful to incorporate farmer perceptions regarding the non-pecuniary benefits from farming in economic models of farm behavior across a range of activities as this could lead to much more accurate predictions of farmers’ responses to policy changes.  相似文献   
69.
The data presented in this review show that past selection for increased milk production in Ireland over a 14-year period (1990 to 2003) resulted in increases in milk production per cow but has been accompanied by undesirable side effects in reproduction and survival. Economic analysis in a EU milk quota scenario over this period showed that only 41% of the potential improvement in farm profit was achieved because of impaired reproductive performance. Strain comparison studies show that genetic selection for increased phenotypic milk production, which is generally accompanied with increased proportion of North American Holstein Friesian genes, was associated with increased milk production per cow, lower body condition score, greater milk production response to concentrate supplementation at pasture and reduced fertility and survival. The lower reproductive performance observed with cows selected solely for high milk production was associated with lower energy balance in early lactation, greater partitioning of additional nutrients towards milk production, inability to achieve desired grass intake from pasture and decreased plasma glucose and insulin like growth factor-1 concentrations. The existence of genotype by environment interactions suggests that germplasm selected in the future should be from within the management system in which it is to be used, and based on a selection index that combines production and other traits of economic importance.  相似文献   
70.
The objective of this study was to compare the biological and economic efficiency of a seasonal pasture‐based spring calving system of milk production on a high‐rainfall, heavy‐clay soil [Kilmaley (KMY)] to that on a lower‐rainfall free‐draining soil [Moorepark (MPN)] in Ireland. The physical performance data were obtained from a 3‐year study (1998–2000) carried out at both sites. Analysis of the system of milk production at the two sites was undertaken using the Moorepark Dairy System Model. Herbage dry‐matter production was greater at the MPN site with a greater proportion being produced between 1 September and 1 May. On average, over the 3 years, the system of milk production at the MPN site had a higher stocking rate (2·34 vs. 1·89 cows ha?1), higher milk production per cow (6421 vs. 5781 kg per cow), longer grazing season (250 vs. 149 d) and a higher proportion of the diet of the herd from grazed grass (0·70 vs. 0·40) than at KMY. Economic analysis showed that, in a 468 100 kg European Union milk quota scenario, the profitability at the MPN site was €28 417 greater than at the KMY site. At similar milk production per cow it was €19 138 greater. Monte Carlo simulation showed that the MPN site was stochastically dominant over the KMY site. Sensitivity analyses showed that farm profit was most sensitive to changes in milk price. The results also indicated that milk production in the future may not be sustainable economically on high‐rainfall, heavy‐clay soils in Ireland.  相似文献   
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