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   50篇
  免费   4篇
林业   2篇
农学   3篇
  21篇
综合类   1篇
农作物   3篇
水产渔业   3篇
畜牧兽医   19篇
植物保护   2篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2019年   2篇
  2018年   1篇
  2017年   2篇
  2016年   3篇
  2015年   2篇
  2014年   3篇
  2013年   3篇
  2012年   7篇
  2011年   7篇
  2010年   1篇
  2009年   2篇
  2008年   2篇
  2007年   1篇
  2006年   3篇
  2005年   1篇
  2004年   5篇
  2003年   2篇
  1997年   2篇
  1972年   1篇
  1971年   1篇
排序方式: 共有54条查询结果,搜索用时 15 毫秒
11.
This article describes atypical interstitial (Leydig) cell tumors in two cryptorchid horses. Ultrasonography allowed accurate localization of the cryptorchid testicles. Ultrasonographic features of the tumor are also presented and may be of value for the clinical diagnosis.Histopathological evaluation of testicular tissue after cryptorchidectomy revealed atypical evolving interstitial (Leydig) cell tumors. Clinically, the tumors reported here appear to have several similarities with the interstitial (Leydig) cell tumors described in the literature, which in most cases appear to be (1) cryptorchidism–induced tumors, (2) often benign and not enlarged, and (3) often associated with aggressive behavior. Although generally considered to be uncommon, equine testicular neoplasms may occur more frequently than previously thought. The use of ultrasonography may improve diagnosis.  相似文献   
12.
In this study, a set of nuclear microsatellite markers were transferred and characterized from two Myrtaceae sub-families to four neotropical Eugenia fruit tree species (E. uniflora L., E. pyriformis Cambess., E. brasiliensis Lam. and E. francavilleana O. Berg), which are neglected and underutilized foods of great ecological and potential economic value found in the Atlantic forest regions of South America. Leaf samples of mature E. uniflora, E. pyriformis, E. brasiliensis and E. francavilleana trees, which are popularly termed “pitanga”, “uvaia”, “grumixama” and “guamirim”, respectively, were collected from two areas greatly impacted by the agricultural practices of the sugar cane industry in the state of São Paulo in the southeastern region of Brazil. A total of 19 simple sequence repeat (SSR) markers from the Myrtaceae sub-families Leptospermoideae and Myrtoideae were tested, and 15 polymorphic heterologous SSR markers were identified. The expected heterozygosities for E. uniflora, E. pyriformis, E. brasiliensis and E. francavilleana were 0.64, 0.75, 0.54 and 0.71, respectively. These results suggest that these SSR markers may be useful for population genetic studies. A total of 4, 9, 11 and 4 heterologous SSR polymorphic markers for E. uniflora, E. pyriformis, E. brasiliensis and E. francavilleana, respectively, are now available for genetic diversity, gene flow and mating system analyses in these species.  相似文献   
13.
14.
Deforestation in southeast Brazil has led to the extinction of Hymenaea courbaril var. stilbocarpa and ex situ conservation has been established. In this study, the levels of genetic diversity and the effective population size of H. courbaril in a germplasm bank were investigated using six nuclear microsatellite loci. A total of 79 and 91 alleles were found in 65 seed-trees and their 176 offspring, respectively. Offspring have a higher average number of alleles per locus (= 15.2) than seed-trees (= 13.2), but lower observed heterozygosity (offspring: H o = 0.566; seed-trees: H o = 0.607). The estimate of outcrossing rate shows that the study population is perfectly outcrossed (t m  = 0.978, > 0.05). Significant deviations from random mating were detected through mating among relatives and correlated matings. The average variance in effective population size for each family was 2.63, with a total effective population size retained in the bank of 170.1. These results confirm that the preserved population of H. courbaril retains substantial genetic variability. Moacyr Antonio Mestriner and Ana Lilia Alzate-Marin—CEEFLORUSP Members.  相似文献   
15.
16.
OBJECTIVE: To investigate the effect of buprenorphine pre-treatment on sufentanil requirements in female dogs undergoing ovariectomy. STUDY DESIGN: Randomized, 'blinded', prospective clinical study. ANIMALS: Thirty healthy female dogs referred for ovariectomy. MATERIALS AND METHODS: Dogs were randomly assigned to one of two pre-anaesthetic treatment groups. Those in the buprenorphine group (B) received buprenorphine 20 microg kg(-1) and acepromazine 0.03 mg kg(-1) IM. Control group (C) animals received an equal volume of NaCl 0.9% and acepromazine 0.03 mg kg(-1) IM. The anaesthetic technique was identical in both groups. Pre-anaesthetic medication consisted of intravenous (IV) sufentanil (1.0 microg kg(-1)) and midazolam (0.05 mg kg(-1)) and intramuscular atropine (0.03 mg kg(-1)). Anaesthesia was induced with propofol and maintained with a constant rate infusion of sufentanil (1.0 microg kg(-1) hour(-1)) and with oxygen-isoflurane. Ventilation was controlled mechanically. Ovariectomy was performed using a standard technique. Baseline heart rate (HR) and direct mean arterial blood pressure (MAP) were recorded before the first incision. Increases in HR and MAP of > or =20% over baseline and, or spontaneous ventilation were controlled using IV sufentanil (1.0 microg kg(-1)) repeated after 5 minutes if haemodynamic variables remained elevated or attempts at spontaneous ventilation persisted. Analysis of variance was used to determine group differences in mean and median HR and MAP and to compare the maximum HR and MAP attained during surgery. Poisson regression was used to compare the number of sufentanil injections required in both groups. RESULTS: Group B required 2.46 times more sufentanil injections (p = 0.00487) than dogs in group C to maintain haemodynamic stability and prevent spontaneous ventilation during surgery. Group B dogs also had a significantly higher (p = 0.034) marginal mean of the log maximum MAP (4.756 +/- 0.036) compared with group C (4.642 +/- 0.036). CONCLUSIONS: Pre-treatment with buprenorphine appears to negatively influence the antinociceptive efficacy of intra-operative sufentanil. CLINICAL RELEVANCE: Withholding buprenorphine therapy 6-8 hours before anaesthesia incorporating pure mu receptor agonists is probably advisable. Alternative methods of analgesia should be provided in this period.  相似文献   
17.
The spatial distribution and coexistence of monogenean dactylogyrids was assessed on the gills of 63 specimens of wild spotted rose snapper, Lutjanus guttatus (Steindachner), caught in the Mazatlan Bay, Sinaloa, Mexico. Five species are reported: Euryhaliotrema perezponcei Garcia-Vargas, Fajer-Avila et Lamothe-Argumedo, 2008, Euryhaliotrematoides sp., Haliotrematoides spinatus Kritsky et Mendoza-Franco, 2009, H. plectridium Kritsky et Mendoza-Franco, 2009, and H. guttati Garcia-Vargas, Fajer-Avila et Lamothe-Argumedo, 2008. All except E. perezponcei and H. guttati represent new geographical records for the Pacific coast. The most prevalent dactylogyrid species was E. perezponcei (100%), H. plectridium and H. spinatus had > 80% prevalence, and H. guttati and Euryhaliotrematoides sp. had the lowest prevalence. The mean abundance of H. plectridium and E. perezponcei was close to 60 parasites/fish, whereas Euryhaliotrematoides sp. and H. guttati had the lowest abundance. The dactylogyrid species exhibited a tendency for attachment to gill arch 2: 25% attachment occurring on gill arch 1, 30% on 2, 27% on 3 and 18% on 4, and showed a significant preference for the central sector of the gill (42%). Haliotrematoides plectridium had a preference for attachment to gill arches 2 and 3 and the central sector. Haliotrematoides spinatus tended to settle on the gill arches 2 and 3 and had a preference for the central sector. Euryhaliotrema perezponcei tended to settle on the gill arches 1 and 2 and the anterior gill sector. Euryhaliotrematoides sp. and H. guttati did not show a preference for any gill arch or sector. The intraspecific aggregation was stronger than the interspecific aggregation, indicating that all the dactylogyrid species on spotted rose snapper were aggregated, and there was no evidence of competition among the species.  相似文献   
18.
19.
Root exudates play a major role in the mobilization of sparingly soluble nutrients in the rhizosphere. Since the amount and composition of major metabolites in root exudates from one plant species have not yet been systematically compared under different nutrient deficiencies, relations between exudation patterns and the type of nutrient being deficient remain poorly understood. Comparing root exudates from axenically grown maize plants exposed to N, K, P, or Fe deficiency showed a higher release of glutamate, glucose, ribitol, and citrate from Fe‐deficient plants, while P deficiency stimulated the release of γ‐aminobutyric acid and carbohydrates. Potassium‐starved plants released less sugars, in particular glycerol, ribitol, fructose, and maltose, while under N deficiency lower amounts of amino acids were found in root exudates. Principal‐component analysis revealed a clear separation in the variation of the root‐exudate composition between Fe or P deficiency versus N or K deficiency in the first principal component, which explained 46% of the variation in the data. In addition, a negative correlation was found between the amounts of sugars, organic and amino acids released under deficiency of a certain nutrient and the diffusion coefficient of the respective nutrient in soils. We thus hypothesize that the release of dominant root exudates such as sugars, amino acids, and organic acids by roots may reflect an ancient strategy to cope with limiting nutrient supply.  相似文献   
20.
Breast cancer resistance protein (BCRP) is a protein belonging to the ATP-binding cassette (ABC) transporter superfamily that has clinical relevance due to its multi-drug resistance properties in cancer. BCRP can be associated with clinical cancer drug resistance, in particular acute myelogenous or acute lymphocytic leukemias. The overexpression of BCRP contributes to the resistance of several chemotherapeutic drugs, such as topotecan, methotrexate, mitoxantrone, doxorubicin and daunorubicin. The Food and Drugs Administration has already recognized that BCRP is clinically one of the most important drug transporters, mainly because it leads to a reduction of clinical efficacy of various anticancer drugs through its ATP-dependent drug efflux pump function as well as its apparent participation in drug resistance. This review article aims to summarize the different research findings on marine natural products with BCRP inhibiting activity. In this sense, the potential modulation of physiological targets of BCRP by natural or synthetic compounds offers a great possibility for the discovery of new drugs and valuable research tools to recognize the function of the complex ABC-transporters.  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