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   32篇
  免费   2篇
林业   8篇
农学   1篇
  7篇
农作物   5篇
水产渔业   4篇
畜牧兽医   6篇
植物保护   3篇
  2023年   1篇
  2022年   3篇
  2021年   1篇
  2020年   1篇
  2019年   2篇
  2018年   2篇
  2017年   1篇
  2016年   3篇
  2015年   1篇
  2014年   1篇
  2013年   1篇
  2012年   2篇
  2011年   1篇
  2009年   1篇
  2006年   2篇
  2004年   1篇
  2003年   3篇
  2002年   1篇
  2000年   1篇
  1999年   1篇
  1988年   1篇
  1865年   1篇
  1861年   1篇
  1857年   1篇
排序方式: 共有34条查询结果,搜索用时 15 毫秒
11.
12.
Nezara viridula (L.) (Hemiptera: Pentatomidae), commonly known in the U.S. as the southern green stink bug (SGSB), is a cosmopolitan, highly polyphagous feeder that causes severe damage to a wide range of agronomically important crops such as fruit, vegetable, grain, tobacco, and cotton, throughout much of the United States, and is a global pest of considerable ecological, agricultural, and economical interest. During dissection of female Nz. viridula, conspicuous black and brown spots or lesions were observed on various internal organs. To determine the cause of these spots or lesions, tissues of fat body, spermatheca, ovaries, and ovulated eggs were collected from healthy and infected individuals. The gross morphology of the spots was characterized, and the microorganisms associated with the infection were identified by amplicon sequencing of the V4 region of the small subunit rRNA gene. The presence of a microsporidian pathogen Nosema maddoxi, Becnel, Solter, Hajek, Huang, Sanscrainte, & Estep (Microsporidia: Nosematidae) which has been observed on other species of stink bug, was evidenced for the first time. The characterization of the gross morphology of this associated microsporidian may enable more rapid determination of microsporidia infection in stink bug colonies and field populations.  相似文献   
13.
OBJECTIVE: To determine the association between the 3-dimensional (3-D) motion pattern of the caudal lumbar and lumbosacral portions of the canine vertebral column and the morphology of vertebrae, facet joints, and intervertebral disks. SAMPLE POPULATION: Vertebral columns of 9 German Shepherd Dogs and 16 dogs of other breeds with similar body weights and body conditions. PROCEDURE: Different morphometric parameters of the vertebral column were assessed by computed tomography (CT) and magnetic resonance imaging. Anatomic conformation and the 3-D motion pattern were compared, and correlation coefficients were calculated. RESULTS: Total range of motion for flexion and extension was mainly associated with the facet joint angle, the facet joint angle difference between levels of the vertebral column in the transverse plane on CT images, disk height, and lever arm length. CONCLUSIONS AND CLINICAL RELEVANCE: Motion is a complex process that is influenced by the entire 3-D conformation of the lumbar portion of the vertebral column. In vivo dynamic measurements of the 3-D motion pattern of the lumbar and lumbosacral portions of the vertebral column will be necessary to further assess biomechanics that could lead to disk degeneration in dogs.  相似文献   
14.
15.
Dogs are companion animals that live in close proximity with humans. Canine H3N2 influenza virus has been isolated from pet dogs that showed severe respiratory signs and other clinical symptoms such as fever, reduced body weight, and interstitial pneumonia. The canine H3N2 influenza virus can be highly transmissible among dogs via aerosols. When we analyzed global gene expression in the lungs of infected dogs, the genes associated with the immune response and cell death were greatly elevated. Taken together, our results suggest that canine H3N2 influenza virus can be easily transmitted among dogs, and that severe pneumonia in the infected dogs may be partially due to the elevated expression of genes related to inflammation and apoptosis.  相似文献   
16.
Journal of Soils and Sediments - Tobacco stems collected from tobacco cultivation fields were pyrolyzed to produce value-added biochar that was used to remediate metal-contaminated soil which was...  相似文献   
17.
18.
This study was conducted in the South East New Territories landfill in Hong Kong, with the objectives to (i) investigate the plant and animal communities' establishment and performance within 10 years after restoration and (ii) provide important information on pioneer plants species selection recommendations for restoring sanitary landfills. The studying sites were re‐vegetated in 2003, with 14 pioneer plant species, including Acacia auriculiformis, A. confusa and Schefflera heptaphylla, planted. In total, four permanent quadrats (10 m × 10 m) were used for monitoring at three restored sites (sites E, N and S) and the control site C. The soil properties and plant and animal communities inside plots were investigated annually in summer and winter between 2003 and 2014. The similarity of plant and animal communities between the restored and control sites was compared using Jaccard's index. Ten years after restoration, animal and plant communities were gradually established at all sites. No animal was introduced into the restored sites in 2003; however, there were 29, 31 and 44 animal species recorded at sites E, N and S, respectively, between 2003 and 2012. Within the studying period, 38 plant species (trees: 52·63%, shrub: 21·05%, herbs: 23·68% and climber: 2·63%) were recorded in all sites and 17 (36·84%) of them were self‐seeding. Exotic species, such as those from the family Acacia and Mimosaceae, were dominant at all restored sites, which implies that exotic species are more competitive and suitable to be used as pioneer species in sanitary landfill restoration. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
19.
Female rainbow trout were exposed over their second reproductive cycle to a simulated natural photoperiod (control group) and to two accelerated photoperiod regimes (S9 and S6 groups). Early spawning was achieved in both accelerated groups, coupled, however, with a reduction of mean egg size. To investigate this reduction of egg size, circulating levels of GTHs and two indices of ovarian growth (gonadosomatic index and follicle diameter) were regularly measured in association with histological studies of structural changes in ovarian follicles. Regardless of the photoperiod regime, the seasonal profile of plasma GTH I levels appeared to be multiphasic. The successive transient elevations in GTH I levels appeared to be connected with the initiation of ovarian growth and vitellogenesis and also, with the synchronization of the late stages of maturation and ovulation. In contrast, the seasonal profile of plasma GTH II levels was monophasic, with a single peak at ovulation, confirming that GTH II is not associated with ovarian growth but promotes gamete maturation and release. Our results demonstrate that the reduction of egg size cannot be due to a deficient secretion of GTH I in plasma, since GTH I levels were much higher during vitellogenesis in both accelerated groups, but rather to an alteration of ovarian follicle growth during the late stages of vitellogenesis. Finally, the early and middle stages of ovarian growth appeared to be photosensitive periods, whereas the late stages were less so, and appeared to be controlled rather by an endogenous biological clock synchronized by the photoperiod.  相似文献   
20.
This study demonstrates that 31P and 1H high resolution-magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR), a recently developed NMR technique, can be applied to the in vivo analysis of metabolites from an unstarved earthworm. The endogeic earthworm Aporrectodea caliginosa was cut into lengths and then the different body parts (anterior, middle, posterior) with the gut content were analyzed. With the HR-MAS NMR, metabolites show well-resolved signals, whereas, with conventional NMR, spectra are highly dependent on the gut content. 31P HR-MAS NMR has been used to evaluate the effect of an acute exposure of the earthworm to glyphosate. Our observations support a low toxicity of the herbicide and suggest that glyphosate could be trapped in the cutaneous mucus. Earthworms could therefore play a role in horizontal dispersion and stabilization of glyphosate in the drilosphere. Phosphorylated metabolites, such as phospholombricine and lombricine, were clearly identified and their amount measured during experiments. The 1H HR-MAS NMR method offers the opportunity to measure, on the same sample and simultaneously, both the hydrosoluble metabolites and lipids. The data on lipid location and relative succinate concentration shed light on the physiological and metabolic functions of the different body parts of the earthworm.  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