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   97篇
  免费   11篇
林业   18篇
农学   4篇
  17篇
综合类   6篇
农作物   10篇
水产渔业   16篇
畜牧兽医   26篇
园艺   2篇
植物保护   9篇
  2023年   1篇
  2022年   7篇
  2021年   2篇
  2020年   5篇
  2019年   5篇
  2018年   7篇
  2017年   4篇
  2016年   9篇
  2015年   3篇
  2014年   5篇
  2013年   6篇
  2012年   6篇
  2011年   5篇
  2010年   1篇
  2009年   4篇
  2008年   3篇
  2007年   2篇
  2006年   3篇
  2005年   3篇
  2004年   5篇
  2003年   3篇
  2002年   5篇
  2001年   1篇
  2000年   2篇
  1999年   2篇
  1996年   1篇
  1988年   2篇
  1927年   3篇
  1865年   1篇
  1861年   1篇
  1857年   1篇
排序方式: 共有108条查询结果,搜索用时 15 毫秒
41.
42.
A 23-year-old captive female California sea lion (Zalophus californianus) developed an inferiotemporal subconjunctival swelling of the right eye. Surgical excision of the mass was performed and a diagnosis of orbital fat prolapse was confirmed histopathologically. There was no recurrence of orbital fat prolapse at 15 months post operatively. This is the first known case of orbital fat prolapse in the California sea lion.  相似文献   
43.
Gelatin was extracted from the skin of Japanese flounder ( Palatichtys olivaceus ) and was subjected to enzymatic hydrolysis. The peptic hydrolysate resulted in a potent antioxidative peptide Gly-Gly-Phe-Asp-Met-Gly (582 Da), which bears +12.61 kcal/mol hydrophobicity. The antioxidative potential of the peptide was characterized by analyzing the protective effect of the peptide on reactive oxygen species (ROS)-mediated intracellular macromolecule damage. It was found that the peptide is a potent scavenger of intracellular ROS, thereby protecting the radical-mediated damage of membrane lipids, proteins, and DNA. Moreover, the peptide is capable of upregulating the expression of inherent antioxidative enzymes, superoxide dismutase-1, glutathione, and catalase. Collectively, it can be concluded that Japanese flounder skin, a processing byproduct of filleting, can be effectively used to produce a bioactive peptide with potent antioxidant capacity.  相似文献   
44.
This research situates new farmers within the counter-urbanization phenomenon, explores their urban–rural migration experiences and examines how they are becoming a part of the rural agricultural landscape. Key characteristics in new farmers’ sense of place constructions are revealed through an ethnographic study conducted in southern Ontario, Canada, during the summer of 2009. Using a sense of place framework comprised of place identity, place attachment, and sense of community, this research details a contemporary concept of place to provide a fresh perspective on new farmers. It uncovers underlying motivations, goals, and values attached to rural agricultural landscapes as well as the “everyday” interactions and challenges experienced by those transitioning into rural farming communities. New farmers are found to draw unevenly from both the physical and social landscape of the urban and rural environments in the creation of a sense of place. This finding raises important questions about the socio-spatial dynamics that underscore the place of food and the local food movement.  相似文献   
45.
46.
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   
47.
In animals and plants, social structure can reduce conflict within populations and bias aggression toward competing populations; however, for bacteria in the wild it remains unknown whether such population-level organization exists. Here, we show that environmental bacteria are organized into socially cohesive units in which antagonism occurs between rather than within ecologically defined populations. By screening approximately 35,000 possible mutual interactions among Vibrionaceae isolates from the ocean, we show that genotypic clusters known to have cohesive habitat association also act as units in terms of antibiotic production and resistance. Genetic analyses show that within populations, broad-range antibiotics are produced by few genotypes, whereas all others are resistant, suggesting cooperation between conspecifics. Natural antibiotics may thus mediate competition between populations rather than solely increase the success of individuals.  相似文献   
48.
49.
Seed storability in rice (Oryza sativa L.) is an important agronomic trait. Two segregating populations with N22 (indica) as a common parent, viz. a set of 122 backcross-inbred lines (BILs) derived from the backcross Nanjing35 (japonica)/N22//Nanjing35 and another population comprising 189 recombinant inbred lines (RILs) from the cross of USSR5 (japonica) and N22, were studied to detect quantitative trait loci (QTL) controlling seed storability. Germination percentage (GP) was used to evaluate seed storability after aging treated under three different conditions, viz. natural, artificial and combined aging treatments. A total of seven QTLs were identified on chromosomes 1, 2, 5, 6 and 9. Among them, a major QTL, qSSn-9, was common in the two populations. In contrast, four QTLs (qSSnj-2-1, qSSn-2-2, qSSn-5 and qSSn-6) were detected in BILs and the QTL qSSn-1 was identified in RILs, which was a new QTL for seed storability. The N22-derived alleles increased the seed storability at all the loci except qSSnj-2-1. We also investigated the effect of QTLs using five selected lines with high storability from BILs and verified qSSn-5 with a near-isogenic line (NIL). These results provide an opportunity for pyramiding or map-based cloning major QTLs for seed storability in rice.  相似文献   
50.
From acidic tea soils of Kagoshima Prefecture in Japan, some soil properties were determined and 38 strains of acid tolerant microorganisms were isolated. Different Al3+ concentrations were applied to YG media to estimate Al resistance. Selected microbial strains could grow strongly in the liquid media in the presence of 100 mM Al3+ and survive even in 300 mM Al3+ at pH 3.0. Their base sequences of 28S rDNA-D1/D2 were determined and sequence data were searched using the Basic Local Alignment Search Tool (BLAST) system. The results of sequencing revealed that the isolates belong to two different species, Cryptococcus sp. and Candida palmioleophila. When cultivated with various Al3+ concentrations, the yeast growth was inhibited at a concentration of 200 mM. Pre-cultivation of these strains with 0–30 mM Al3+ did not promote the growth response caused by Al3+. Inductively-Coupled Plasma-Mass Spectrometry (ICP-MS) was used to assess the elimination of Al. The amount of Al remaining in culture media was decreased considerably after cultivation. Due to a capacity for resistance to significant Al concentrations as well as high Al elimination, these acid tolerant and Al resistant yeasts may have potential applications in the bio- and phyto-remediation of Al and acid-contaminated soils.  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