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   91篇
  免费   7篇
林业   9篇
农学   6篇
  22篇
综合类   9篇
农作物   6篇
水产渔业   7篇
畜牧兽医   32篇
植物保护   7篇
  2023年   1篇
  2022年   3篇
  2021年   3篇
  2020年   5篇
  2019年   6篇
  2018年   2篇
  2017年   5篇
  2016年   7篇
  2015年   4篇
  2014年   4篇
  2013年   6篇
  2012年   8篇
  2011年   11篇
  2010年   1篇
  2009年   2篇
  2008年   1篇
  2007年   5篇
  2006年   4篇
  2005年   5篇
  2004年   7篇
  2003年   5篇
  2002年   2篇
  1999年   1篇
排序方式: 共有98条查询结果,搜索用时 15 毫秒
91.
The antioxidant activity of the methanol extract of Filipendula hexapetala flowers was assessed by the assay for ferric-reducing antioxidant power (FRAP), the assay for DPPH free radical scavenging ability (DPPH) and the assay for the influence of lipid peroxidation in liposomes, induced by Fe(2+)/ascorbate system and measured by the TBA test (LP). The activity of the investigated extract in all test-systems was found to be significant. The principal constituent responsible for the observed effects was isolated and identified as spiraeoside.  相似文献   
92.
The present work was aimed at evaluating the effects of maternal exposure to potassium cyanide (KCN) during lactation in goats. Twenty-seven lactating female goats were orally dosed with 0 (control), 1.0, 2.0, or 3.0 mg KCN/kg body weight/day from lactation days 0 to 90. After this period, all male kids and one mother from each group were killed for a pathological study. Cyanide treatment promoted the clinical signs of maternal toxicity in the highest KCN group but did not affect body weight. Both cyanide and thiocyanate presented increased levels in both dams and kids from the treated groups. Microscopic lesions, but without alterations on the biochemical panel, were found in the brain, thyroid, liver, and kidneys of both dams and kids from the treated groups. These findings suggest that lactating offspring can be indirectly intoxicated by maternal exposure to cyanide.  相似文献   
93.
Andean Potato is a major crop for farmers in the Andes and represents an important gene pool for potato improvement. We present the population structure and genetic diversity of 88 Andigena accessions collected in Northwestern Argentina based on functional markers (25 SSR) distributed along 12 chromosomes. Polymorphic information content ranged from 0.40 to 0.87. A Bayesian approach, a Principal Coordinate Analysis and a Cluster Analysis revealed the presence of: I) a major group containing most of the Andean accessions and II) a smaller group including the out-group cv. Spunta and the sequenced genotype DM. Several group specific alleles were detected. AMOVA showed that 81% of the variability was within each group. Eleven of the SSRs analyzed are linked or within genes reported to regulate traits of nutritional and industrial interest. Additionally, the allelic variant of a photoperiod dependent tuberization regulator gene, StCDF1.2, was exclusively detected in accessions clustered in group II.  相似文献   
94.
Since in the aged heart an increased basal production of reactive oxygen species (ROS) has been demonstrated, and the resistance to ROS attack could be ameliorated by antioxidant supplementation, we verified the protective effect of selenium, as sodium selenite (SS) or seleno methionine (SM), in cultured rat cardiomyocytes aged in vitro. In normoxia, glutathione peroxidase (GPx) activity and total antioxidant activity were higher in old than in young cardiomyocytes, suggesting the existence of a compensatory increase of antioxidant defenses. When aged cells were submitted to hypoxia/reoxygenation, GPx activity was not modified; while total antioxidant activity decreased, conjugated diene level increased. Selenium supplementation, particularly as SM, was able to increase GPx, and consequently total antioxidant activity, and to decrease conjugated diene production. The observed ability of selenium supplementation to protect aged cardiomyocytes from hypoxia/reoxygenation damage underlines the importance of an optimal selenium dietary intake, particularly in the elderly.  相似文献   
95.
European Journal of Plant Pathology - Volatile fatty acids (VFAs) play a role in suppression of plant pathogens during anaerobic soil disinfestation (ASD), but it is unclear how VFAs in anaerobic...  相似文献   
96.
Leptospirosis is an endemic disease in Latin America, caused by pathogenic bacteria of the genus Leptospira. It is considered one of the main causes responsible for the negative economic impact on global livestock by causing reproductive problems. The research aimed to determine the prevalence of leptospirosis in cattle, sheep, and goats at consorted rearing in the micro-region of Teresina, Piauí state, northeastern Brazil, as well as to identify prevalent serovars and risk factors associated with seroprevalence. Serum samples were analyzed in 336 sheep, 292 goats, and 253 cattle using microscopic agglutination test (MAT). Overall, 378 samples were positive to MAT, with seroprevalence of 42.9%. The prevalences in cattle, sheep, and goats were 50.5, 40.5, and 34.6%, respectively. All herds presented at least one seropositive animal; the Hardjo/Wolffi serovar association was the most common in cattle and Icterohaemorrhagiae in goats and sheep. Beef production (OR?=?4.9), cattle herd over 35 animals (OR?=?4.0), feeding on pasture (OR?=?6.4), weir and/or stream as water source (OR?=?2.1), and no veterinary services (OR?=?2.9) were risk factors for cattle infection. For sheep, intensive management system (OR?=?5.3), suspended slatted facilities (OR?=?2.2), more than 20 sheep in reproductive age (OR?=?1.9), and absence of deworming (OR?=?3.5) were the risk factors, while for goats, the identified risk factors were sheep herd over 52 animals (OR?=?1.9) and no veterinary services (OR?=?1.8). We conclude that the infection was spreading in consorted herds in this region. Thus, it would be interesting and important to conduct educative activities to farmers on the economic impacts of this disease and the need of preventive and control strategies mainly focused on sanitary measures and animal handling.  相似文献   
97.
This paper characterizes wood and charcoal made from Hymenaea aurea, Mimosa scabrella, Tabebuia capitata and Eucalyptus alba by scanning electron microscopy and near infrared for the purpose of developing a technique to identify the source of charcoal samples. Ten test samples were prepared for each species, oriented in transverse, radial and tangential section. Samples were carbonized in a muffle furnace with a final temperature of 450 °C and a heating rate of 1.66 °C/min. The microscopic structures of the wood and charcoal samples were verified by scanning electron microscopy, and spectra were obtained with a spectrophotometer, equipped with an integrating sphere and operating in transmittance mode. The spectra of the wood samples present characteristic bands of lignocellulosic material, while the spectra of the charcoal samples show small or nil absorption in the near-infrared region. The near-infrared spectroscopy technique was efficient in discriminating the four species studied.  相似文献   
98.
The 18S ribosomal DNA molecular phylogeny and lipid composition of over 120 marine diatoms showed that the capability to biosynthesize highly branched isoprenoid (HBI) alkenes is restricted to two specific phylogenetic clusters, which independently evolved in centric and pennate diatoms. The molecular record of C25 HBI chemical fossils in a large suite of well-dated marine sediments and petroleum revealed that the older cluster, composed of rhizosolenid diatoms, evolved 91.5 +/- 1.5 million years ago (Upper Turonian), enabling an accurate dating of the pace of diatom evolution that is unprecedented. The rapid rise of the rhizosolenid diatoms probably resulted from a major reorganization of the nutrient budget in the mid-Cretaceous oceans, triggered by plate tectonics.  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