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71.
72.
Since the 1970s the control of bovine tuberculosis (bTB) in cattle, predominantly in the SW of England has proved continually recalcitrant; it is currently increasing at an annual rate of 18%. This deterioration has occurred despite a succession of government schemes involving killing badgers, Meles meles, with the intention of reducing transmission of bTB to cattle. Of various hypotheses proposed to explain this failure of control, some concern agricultural practice, but two concern wildlife. The latter are, first, that wild mammalian species other than badgers are important in the transmission of bTB, and second, that a perturbation effect amongst those badgers surviving a cull countermands the hoped-for reduction of bTB transmission to cattle or even increases it. We review our own studies of these two hypotheses in the context of other findings. We conclude that the other species hypothesis does not provide a general explanation for the failure of bTB control. We also conclude that the perturbation hypothesis is supported by the data and does provide one plausible mechanism to explain why culling badgers has not generally achieved control of bTB in cattle. We have reviewed the relevance of perturbation with respect to three key questions:
(a)
is there evidence of a perturbation effect on badger behavioural ecology?
(b)
is there evidence of a perturbation effect on prevalence of bTB in badgers?
(c)
are any observed effects of a magnitude relevant to bTB control policy?
The results of the Randomised Badger Culling Trial (RBCT) and our own studies indicate that to have any prospect of contributing significantly to controlling bTB in cattle, a badger cull would have to be undertaken over a very large area. Considering the likely very important role of cattle-to-cattle transmission, and the opportunities for solutions in terms of farm management and surveillance, it would be inappropriate (and probably impractical) to undertake such a cull now.  相似文献   
73.
OBJECTIVE: To determine whether duration of hospitalization in the intensive care unit (ICU) of a veterinary teaching hospital was associated with prevalence of antimicrobial resistance among rectal Escherichia coli isolates from dogs, whether antimicrobial treatment was associated with prevalence of antimicrobial resistance, and whether there were associations among antimicrobial drugs to which isolates were resistant. DESIGN: Prospective observational study. ANIMALS: 116 dogs hospitalized in an ICU for >or= 3 days. PROCEDURES: Rectal swab specimens were obtained every 3 days and submitted for bacterial culture for E coli. Isolates were tested for susceptibility to 12 antimicrobial agents by means of disk diffusion. RESULTS: For each additional day that a dog was hospitalized in the ICU, the odds of being colonized with an E coli isolate resistant to 1 or more of the 12 antimicrobials tested increased by a factor of 1.5, independent of antimicrobial treatment. Dogs that were treated with enrofloxacin were 25.6 times as likely to be colonized by a quinolone-resistant E coli strain as were dogs that did not receive any antimicrobials. Significant correlations were found for resistance to agents in the extended-spectrum cephalosporin group and the quinolone group. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the proportion of rectal E coli isolates obtained from dogs housed for >or= 3 days in a veterinary teaching hospital ICU that were resistant to antimicrobial agents increased as the duration of hospitalization in the ICU increased. Thus, ICU hospitalization time should be as short as possible to prevent development of antimicrobial resistance among rectal E coli isolates.  相似文献   
74.
75.
VORTEX computer simulations were used to assess the viability of a small breeding flock of common cranes, recently established in Norfolk. Investigations were also conducted on the relative impact of various management options. Raising the carrying capacity of the site had little influence on the survival of the flock. However, great improvements were associated with increases in the size of the founder flock and reductions in the mortality rates of chicks and adults. Regularly supplementing the population increased flock survival times: for a fixed total number of birds added, frequently supplementing with few birds produced the best results. Immigration from the population in continental Europe also increased persistence of the flock, and it is possible that immigration rates will improve as the British flock expands. Strategies including captive breeding, and regular supplementation of the flock, may be the most effective means of ensuring the viability of the Norfolk cranes. The potential value of simulation models in guiding management of small populations is discussed.  相似文献   
76.
Reintroductions and translocations are increasingly used as conservation tools. However, despite guidelines recommending that health-screening be an integral part of such programmes, few reports are available. For most species, even baseline data, against which to compare future results, are not published. Here we report two case studies of health surveillance in wildlife reintroduction programmes - for water voles (Arvicola terrestris) in Australia, and for marsupial dibblers (Parantechinus apicalis) in the UK. These illustrate the potential importance of even basic screening strategies in helping to avoid disease transfer and identifying predictors of survival. Factors to be considered in the design of future monitoring schemes are also discussed.  相似文献   
77.
OBJECTIVE: To assess accuracy and reliability of open-flow indirect calorimetry in dogs. ANIMALS: 13 clinically normal dogs. PROCEDURE: In phase 1, oxygen consumption per kilogram of body weight (VO2/kg) was determined in 6 anesthetized dogs by use of open-flow indirect calorimetry before and after determination of VO2/kg by use of closed-circuit spirometry. In phase 2, four serial measurements of VO2 and carbon dioxide production (VCO2) were obtained in 7 awake dogs by use of indirect calorimetry on 2 consecutive days. Resting energy expenditure (REE) was calculated. RESULTS: Level of clinical agreement was acceptable between results of indirect calorimetry and spirometry. Mean VO2/kg determined by use of calorimetry before spirometry was significantly greater than that obtained after spirometry. In phase 2, intraclass correlation coefficients (ICC) for REE and VO2 were 0.779 and 0.786, respectively, when data from all 4 series were combined. When the first series was discounted, ICC increased to 0.904 and 0.894 for REE and VO2, respectively. The most reliable and least variable measures of REE and VO2 were obtained when the first 2 series were discounted. CONCLUSIONS AND CLINICAL RELEVANCE: Open-flow indirect calorimetry may be used clinically to obtain a measure of VO2 and an estimate of REE in dogs. Serial measurements of REE and VO2 in clinically normal dogs are reliable, but a 10-minute adaption period should be allowed, the first series of observations should be discounted, multiple serial measurements should be obtained, and REE.  相似文献   
78.
A radiographic study of the anatomy of the canine acetabulum was performed. The relationship between the area of dorsal acetabular rim that is subject to early damage in dogs with coxofemoral joint laxity, and the "DAR point" identified on dorsal acetabular rim (DAR) radiographic views was examined. Radiographs and digital photographs were made of the pelvis harvested from each of six skeletally mature dogs. Through analysis of these images, it was determined that in the standing animal, the DAR point is located 4–6 mm (or approximately 37°) caudal to the dorsal acetabular rim area that is prone to early damage in dogs with coxofemoral joint laxity. This study suggests that the DAR radiographic view may under-represent changes to the dorsal acetabular rim in dogs with coxofemoral laxity.  相似文献   
79.
Two species, Trifolium glomeratum and T. nigrescens, from Sardinia, Italy, were analysed for genetic diversity using amplified fragment length polymorphism (AFLP). Variation between and within populations was compared between the inbreeder, T. glomeratum, and the outbreeder, T. nigrescens. Four AFLP primer combinations resulted in a total of 292 loci, of which 75% were polymorphic in T. glomeratum and 85% in Trifolium nigrescens. Variation was highest between populations in both species, but the difference between populations was greater in T. glomeratum (Fst = 0.17), compared with T. nigrescens (Fst = 0.02). Cluster analysis and principal coordinates analysis were used to verify the relationships found. The high level of genetic variation within populations in both species is attributed to the movement of sheep between paddocks, the existence of both species in Sardinia for thousands of years and the persistence of a long‐lived seedbank due to the production of large numbers of small seeds with high levels of hard seededness.  相似文献   
80.
Background: Scores allowing objective stratification of illness severity are available for dogs and horses, but not cats. Validated illness severity scores facilitate the risk‐adjusted analysis of results in clinical research, and also have applications in triage and therapeutic protocols. Objective: To develop and validate an accurate, user‐friendly score to stratify illness severity in hospitalized cats. Animals: Six hundred cats admitted consecutively to a teaching hospital intensive care unit. Methods: This observational cohort study enrolled all cats admitted over a 32‐month period. Data on interventional, physiological, and biochemical variables were collected over 24 hours after admission. Patient mortality outcome at hospital discharge was recorded. After random division, 450 cats were used for logistic regression model construction, and data from 150 cats for validation. Results: Patient mortality was 25.8%. Five‐ and 8‐variable scores were developed. The 8‐variable score contained mentation score, temperature, mean arterial pressure (MAP), lactate, PCV, urea, chloride, and body cavity fluid score. Area under the receiver operator characteristic curve (AUROC) on the construction cohort was 0.91 (95% CI, 0.87–0.94), and 0.88 (95% CI, 0.84–0.96) on the validation cohort. The 5‐variable score contained mentation score, temperature, MAP, lactate, and PCV. AUROC on the construction cohort was 0.83 (95% CI, 0.79–0.86), and 0.76 (95% CI, 0.72–0.84) on the validation cohort. Conclusions and Clinical Importance: Two scores are presented enabling allocation of an accurate and user‐friendly illness severity measure to hospitalized cats. Scores are calculated from data obtained over the 1st 24 hours after admission, and are diagnosis‐independent. The 8‐variable score predicts outcome significantly better than does the 5‐variable score.  相似文献   
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