首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   75篇
  免费   13篇
林业   1篇
基础科学   1篇
  3篇
综合类   8篇
农作物   2篇
水产渔业   1篇
畜牧兽医   68篇
植物保护   4篇
  2023年   1篇
  2019年   2篇
  2018年   3篇
  2017年   6篇
  2016年   3篇
  2015年   3篇
  2014年   8篇
  2013年   3篇
  2012年   2篇
  2011年   1篇
  2010年   2篇
  2009年   7篇
  2007年   3篇
  2005年   2篇
  2004年   1篇
  2003年   2篇
  2001年   2篇
  2000年   2篇
  1998年   5篇
  1997年   5篇
  1996年   3篇
  1995年   2篇
  1994年   4篇
  1993年   1篇
  1992年   1篇
  1990年   4篇
  1988年   2篇
  1985年   3篇
  1983年   1篇
  1977年   2篇
  1967年   1篇
  1955年   1篇
排序方式: 共有88条查询结果,搜索用时 15 毫秒
71.
72.
Aosta Black Pied (ABP) and Aosta Chestnut (AC) are dual-purpose cattle indigenous to the western Alps and famous for their fighting ability in traditional Italian Batailles de Reines. The present study aimed to investigate the influence of inbreeding on breeding values for fighting ability achieved in participants. Inbreeding (F) and average relatedness (AR) were obtained from the entire pedigree information available (19,554 and 87,967 records for ABP and AC, respectively). Data (n = 23,998) relating to 8,259 cows competing in years 2001-2009 were analyzed to obtain heritability (h(2)) estimates and breeding values for the trait. A placement score was chosen as a phenotype for fighting ability and both a classical quantitative model (NORM) and its implementation, used to identify its indirect genetic effects (COMP), were analyzed using the expectation maximization-REML (EM-REML) method. The F and AR trends in animals born between 1990 and 2009 were generally low and were greater for ABP (+0.06%/yr) than for AC (+0.03%/yr) populations, which also presented a greater mean F (about 2.8% ± 1.7% vs. 0.8% ± 1.5% for ABP and AC, respectively) and mean AR among individuals (about 1.0% ± 0.8% vs. 0.4% ± 0.3% for ABP and AC, respectively). Heritability estimates from 0.083 ± 0.036 to 0.120 ± 0.037 were obtained using the NORM model, accounting for or not accounting for F, respectively. Similar results were obtained also for the COMP model, with h(2) estimates of 0.12 ± 0.037, whether or not F was taken into consideration. Linear regression analyses carried out on the 33 major lineages to which most of participants belonged (n = 6,087) revealed an overall negative trend of EBV compared with the increase of either F (b = -21.3, P < 0.01) or AR (b = -50.1, P < 0.01). However, a great variability in the relationship between EBV and F or AR was found by analyzing data within lineages. Despite the variability, an unfavorable effect of inbreeding was detected in the fighting ability trait of both ABP and AC cattle, and this should be carefully considered in the breeding management of both breeds.  相似文献   
73.
The nutritive value and fermentation quality of palisadegrass (Brachiaria brizantha cv. Xaraes) and stylo (Stylosanthes capitata × S. macrocephala cv. Campo Grande) mixed silages were evaluated. The experiment was analyzed in a factorial scheme (5 × 2) in a completely randomized design using increasing levels of stylo (0, 25, 50, 75 and 100% on a fresh matter basis) on palisadegrass silages, with and without microbial inoculants (MI). With the increased ratio of stylo in mixed silages, dry matter (DM), crude protein (CP), acid detergent fiber (ADF), and lignin content increased in silages. The presence of MI promoted lower DM content, and higher neutral detergent fiber corrected for ash and protein, ADF and lignin content. The acid detergent insoluble nitrogen content and the lactic acid bacteria populations were not affected by treatments. The in vitroDM digestibility was affected by the interaction of levels of the stylo and MI. The pH, NH3‐N/total nitrogen and butyric acid concentrations decreased with increasing levels of stylo. Better nutritive value and quality of fermentation was found in the silage containing higher proportions of this stylo mixed with palisadegrass. The microbial inoculant evaluated did not alter the nutritive value or quality of the fermentation of the silages in this experiment.  相似文献   
74.
The aim of this study was to compare the effects of treatment with repeated injections of sulpiride (a dopamine D2 antagonist) on prolactin secretion and induced lactation in ovariectomized and intact adult mares and to verify if this induction was possible at the beginning and at the end of the birth season. Two experiments were carried out in September [experiment (expt) 1], and in March (expt 2), in France (48°N). In expt 1, three groups of five mares were tested: intact‐control, intact‐treated and ovariectomized‐treated mares. In expt 2, mares previously subjected to artificial photoperiod were assigned in two groups: four intact‐control and five intact‐treated mares. The cyclicity of intact mares was previously synchronized with PGF2α injections, then all the mares were in the follicular phase at the beginning of treatment. Sulpiride was intramuscularly injected (0.5 mg/kg of BW), twice a day. Mares were milked at 7:30, 11:45, 16:00 and 20:15 hours. Blood samples were collected every day during the treatment for progesterone, total oestrogen and prolactin assays. In the two experiments, only treated intact mares produced milk, with a large inter‐animal variability. Prolactin increase after sulpiride treatment was not so great in the ovariectomized‐treated mares as in the intact‐treated mares. The total correlations between prolactin, progesterone, oestrogen plasma concentrations and daily milk production were significant (0.57, 0.25, 0.17 respectively). This induction of lactation can be performed during the entire birth season in intact mares, but not in ovariectomized mares, indicating that steroids are necessary for this induction in mares treated by dopamine D2 antagonist.  相似文献   
75.

BACKGROUND

Helicoverpa zea, an economic pest in the south-eastern United States, has evolved practical resistance to Bacillus thuringiensis (Bt) Cry toxins in maize and cotton. Insect resistance management (IRM) programs have historically required planting of structured non-Bt maize, but because of its low adoption, the use of seed blends has been considered. To generate knowledge on target pest biology and ecology to help improve IRM strategies, nine field trials were conducted in 2019 and 2020 in Florida, Georgia, North Carolina, and South Carolina to evaluate the impact of Bt (Cry1Ab + Cry1F or Cry1Ab + Cry1F + Vip3A) and non-Bt maize plants in blended and structured refuge treatments on H. zea pupal survival, weight, soil pupation depth, adult flight parameters, and adult time to eclosion.

RESULTS

From a very large sample size and geography, we found a significant difference in pupal mortality and weight among treatments in seed blends with Vip3A, implying that cross-pollination occurred between Bt and non-Bt maize ears. There was no treatment effect for pupation depth, adult flight distance, and eclosion time.

CONCLUSION

Results of this study demonstrate the potential impact of different refuge strategies on phenological development and survival of an important pest species of regulatory concern. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   
76.
77.
Objective: To investigate the presence of Salmonella Dublin in Queensland cattle.
Design: An epidemiological study using diagnostic laboratory information and farm records.
Procedure: Outbreaks of gastroenteritis or pneumonia in calves, and abortions and enteritis in cows were routinely investigated for the presence of salmonellae. Where S Dublin was isolated, attempts were made to gather further epidemiological information.
Results: Prior to 1983 only two outbreaks of S Dublin have been recorded in Queensland dairy cattle. In 1983 S Dublin abortions were diagnosed in dairy heifers introduced from southern Australia to south-east Queensland. Sampling indicated that at least 10% of the 500 introduced heifers were faecal excretors of S Dublin. On 3 of the 7 farms from which S Dublin was recorded, infection spread to other cattle that were in contact. From February 1985 to February 1996, 29 outbreaks of S Dublin in cattle occurred on 29 farms (28 in south east Queensland and 1 in north Queensland). Calves were primarily affected. Continuing outbreaks were confirmed on only 4 of these 29 farms. On 15 farms S Dublin infections were associated with the purchase of infected calves or cows, while another farm adjoined 2 previously infected farms. No source of S Dublin was evident for the other 13 farms, where histories were often inadequate.
Conclusion: There has been a marked increase in S Dublin outbreaks in Queensland dairy cattle since 1983. Introduction of S Dublin carrier and aborting dairy heifers from southern Australia, where S Dublin is not uncommon, was associated with the initial outbreaks.  相似文献   
78.
The pattern of human dermatomycoses has changed in Italy during this century, as a progressive escalation of zoophilic dermatophytes over anthropophilic dermatophytes has been experienced: dermatophytozoonoses now prevail over other dermatophytoses (by anthropophilic and geophilic mycetes). Urban dermatophytozoonoses are caused mainly byMicrosporum canis and are an important problem in young people in cities. Many cats and dogs are symptomless carriers of the fungus. Rural dermatophytozoonoses are caused byTrichophyton verrucosum andT. mentagrophytes. They are an important economic problem in calf, rabbit and laboratory animal farms. They are an occupational disease of agricultural workers: family members may also be affected.
Kurzfassung Im letzten Jahrhundert hat sich das Vorkommen von Dermatomykosen bei Menschen in Italien sehr verändert, seitdem man festgestellt hat, dass die zoophylen Dermatophyten die Uberhand über die antropophylen gewinnen, d.h. augenblicklich gibt es mehr Dermatophytozoonosen als andere, von antropophylen und geophylen Pilzen hervorgerufene Dermatophytosen. Die in Städten vorkommenden Dermatophytozoonosen werden hauptsächlich von Microscarum canis bewirkt; sie stellen ein wichtiges Problem für die Stadtjugend dar. Viele Katzen und Hunde sind symptomlose Träger dieser Pilze. Die Dermatophytozoonosen ländlicher Gebiete werden durchTrichophyton verrucosum undT. mentagrophytes hervorgerufen. Sie stellen ein ökonomisches Problem für die Aufzucht von Kälbern, Kaninchen und Labortieren dar. Sie müssen ebenfalls als Berufskrankheit der Landarbeiter angesehen und können auch auf Familienmitglieder übertragen werden.

Resume Le tableau des dermatomycoses s'est modifié en Italie au cours de ce siècle au fur et à mesure qu'on constatait que les dermatophytes zoophiles prenaient le pas sur les anthropophiles: les dermatophytozoonoses l'emportent actuellement sur les cutres dermatophytoses (mycètes anthropophiles et géophiles). Les dermatophytozoonoses urbaines sont causées principalement parMicrosporum canis et constituent un problème important chez les jeunes dans les villes. Beaucoup de chats et chiens sont des porteurs asymptomatiques du champignon. Les dermatophytozoonoses rurales sont provoquées parTrichophyton verrucosum etT. mentagrophytes. Elles représentent un problème économique important chez le veau, le lapin et dans les élevages d'animaux de laboratoire. Elles constituent une maladie professionnelle des travailleurs agricoles; les membres de leur famille peuvent être également affectés.

Riassunto Nel corso di questo secolo la tavola delle dermatomicosi umane si è modificata in Italia a seguito di un progressivo aumento dei dermatofiti zoofili in relazione e quelli antropofili: le dermatofitizoonosi attualmente sono più frequenti delle altre dermatofitosi (miceti antropofili e geofili). Le dermatofitozoonosi urbane sone causate principalmente dalMicrosporum canis e costituiscono un problemaeconomico importante per la popolazione giovane della città. Molti gatti e cani sono portatori asintomatici di questo fungo. Le dermatofitozoonosi rurali sono provocate dalTrichophyton verrucosum e dalT. mentagrophytes. Esse rappresentano un problema importante per il vitello, il coniglio e per gli allevamenti di animali da laboratorio e costituiscono una malattia professionale per i lavoratori agricoli e i membri delle loro famiglie.
  相似文献   
79.
The presence of visna-maedi in Italy is reported for the first time. History, clinical findings and gross and microscopic lesions typical of the disease were observed in two sheep flocks in Central Italy. Affected animals were afebrile, lacked energy, lost condition and had progressively worsening dyspnoea which ended fatally. A few showed locomotor disturbances but remained alert. Anaemia and leukopenia were present. The lungs were affected with fleshy consolidation. Histologically, the pulmonary lesions included bronchiolar epithelial hyperplasia, peribronchiolar lymphoid cuffing, alveolar epithelialization and very marked interstitial changes. In agar gel diffusion tests on sera from 106 animals from the two flocks, 44 were positive. Furthermore, when the same test was conducted as a preliminary screening procedure on 682 animals randomly chosen from 94 flocks in five Regions, 93 positive animals were revealed in 39 flocks, involving all of the Regions. The infection is likely to be widespread in Italy and to constitute a problem in at least some flocks or areas.  相似文献   
80.
SUMMARY Common tiger snake (Notechis scutatus) venom was administered experimentally to dogs at doses from 0.25 lethal dose (LD) to 20 LD. Haemolysis and increased creatine kinase values occurred rapidly after injection of sublethal (subparalytic) doses, but the clotting time of blood was extended and blood became incoagulable only when dogs were dosed with 10 LD or more of venom. Haemolysis, although of a low threshold of toxicity, was not severe and should not greatly affect the lethality of the venom. Coagulopathy is a sign that the dog has been lethally envenomed and will need to be given antivenom if skeletal muscle paralysis is to be overcome.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号