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   71篇
  免费   4篇
  国内免费   1篇
林业   11篇
农学   3篇
  10篇
综合类   4篇
农作物   2篇
水产渔业   29篇
畜牧兽医   10篇
植物保护   7篇
  2022年   1篇
  2021年   3篇
  2020年   2篇
  2019年   4篇
  2018年   3篇
  2017年   3篇
  2016年   3篇
  2015年   3篇
  2014年   1篇
  2013年   9篇
  2012年   10篇
  2011年   2篇
  2010年   8篇
  2009年   3篇
  2008年   5篇
  2007年   4篇
  2006年   2篇
  2005年   7篇
  2003年   2篇
  1997年   1篇
排序方式: 共有76条查询结果,搜索用时 187 毫秒
1.
Summary Aluminum toxicity due to the cation Al+3 is a major factor limiting yields in acid soils. Wide genetic variability to aluminum tolerance is found in oat genotypes. The objectives of this study were to determine the number of genes controlling aluminum tolerance in oats and to verify if any detrimental effects were present of the aluminum tolerance genes on grain yield and grain quality in Al+3free soils. Aluminum tolerance was estimated as the average regrowth of the main root after exposure to toxic levels of Al+3 in a hydroponic solution under controlled conditions. The number of genes controlling that trait was estimated from the distribution of the average root regrowth frequencies in a population of 333 recombinant inbred lines (RIL's) in generations F5:6 and F5:7. The effects on grain yield and grain quality were assessed in a subpopulation of 162 RIL's chosen based on their aluminum tolerance response. Aluminum tolerance in the evaluated population was controlled by one dominant major gene with the tolerant genotypes carying Al a Al a and the sensitive ones al a al a alleles. No detrimental effects of the Al a allele on grain yield or grain quality were detected.Part of the Master of Science dissertation of the first author  相似文献   
2.
大豆根构型在玉米/大豆间作系统中的营养作用   总被引:23,自引:0,他引:23  
 运用根构型不同的大豆品种与玉米进行间作,比较大豆根构型在玉米/大豆间作系统中的营养作用。结果表明,玉米与大豆间作具有明显的间作优势,间作作物的生物量、氮磷含量都显著好于单作。玉米与浅根型大豆品种巴西10号间作,间作优势大于与深根型大豆品种本地2号。说明大豆根构型在玉米/大豆间作系统中具有十分重要的作用。间作系统的氮磷养分竞争比率表明,玉米/大豆这类豆科/禾本科间作组合的优势主要来自对氮的优势性吸收,而玉米与不同基因型大豆间作的优势差异则主要来源于对土壤磷吸收的差异。浅根型大豆品种不仅有利于两种间作作物对土壤磷的吸收,同时还有利于对氮的吸收。  相似文献   
3.
Synchrotron radiation and the time-correlated single-photon counting technique were used to investigate the spectral and time-resolved characteristics of blue-green fluorescence (BGF) of artichoke leaves. Leaves emitted BGF under ultraviolet (UV) excitation; the abaxial side was much more fluorescent than the adaxial side, and in both cases, the youngest leaves were much more fluorescent than the oldest ones. The BGF of artichoke leaves was dominated by the presence of hydroxycinnamic acids. A decrease in the percentage of BGF attributable to the very short kinetic component (from 42 to 20%), in the shape of the BGF excitation spectra, and chlorogenic acid concentrations indicate that there is a loss of hydroxycinnamic acid with leaf age. Studies on excitation, emission, and synchronized fluorescence spectra of leaves and trichomes and chlorogenic acid contents indicate that chlorogenic acid is one of the main blue-green fluorophores in artichoke leaves. Results of the present study indicate that 20-42% (i.e., the very short kinetic component) of the overall BGF is emitted by chlorogenic acid. Time-resolved BGF measurements could be a means to extract information on chlorogenic acid fluorescence from the overall leaf BGF.  相似文献   
4.
The aim of this article was to describe a case of a 7-year-old mare with chronic laminitis secondary to pituitary pars intermedia dysfunction that was successfully treated with autologous platelet concentrates (APC) obtained by the tube method, 4 months before being treated with oral pergolide. After the diagnosis of pituitary pars intermedia dysfunction, the patient was treated with three intralesional injections of APC at 10-day intervals. APC presented a mean concentration of 430 ± 22 × 106 platelets and 8.6 ± 1.3 leukocytes/mL. The treatment with APC produced growth of the hooves at a rate of 5 mm/wk and substantially reduced the foot pain (lameness) after two APC applications. The mare could be ridden 2 weeks after the third APC treatment. The treatment with oral pergolide 4 months later improved the clinical picture of the patient, albeit hirsutism remained. APC could be useful as adjunctive treatment of chronic laminitis in horses. However, additional clinical studies are necessary to determine the safety and effectiveness of APC in chronic laminitis.  相似文献   
5.
<正>Fertium总部位于西班牙萨拉戈萨市,隶属于Tervalis集团,是一家专业化肥生产商和服务分公司,为种植者提供作物营养方面最先进的技术产品,注重农业的可持续发展、尊重环境,提倡合理使用农业营养产品,责任是既满足当下农业需求,而不损害未来的可能性。  相似文献   
6.
7.
Physiological responses to a high stocking density were tested in juvenile wedge sole Dicologoglossa cuneata (Moreau). Fish were kept at low (1 kg m−2), medium (3 kg m−2) and high (9 kg m−2) stocking densities for 22 days. No differences in the weight, length, survival and hepatosomatic index were observed among treatments. Basal plasma cortisol and osmolality were found to be directly and positively related to stocking density. A mild increase in plasma glucose was seen at medium density, and plasma protein was elevated at medium and high densities. The liver glucose and glycogen content was inversely related to stocking density. The liver triglyceride level was significantly elevated at the highest density, and the α-amino acid content decreased at the highest density. In muscle, glucose levels were significantly higher in fish kept at the lowest density; the α-amino acid content was elevated in fish kept at high density. In conclusion, plasma cortisol levels indicated an increasing stress level depending on the culture density, but significant changes in energy reserves did not occur in tissue (mainly liver and muscle glycogen and glucose reserves were significantly affected).  相似文献   
8.
The weaning phase can be decisive in fish-culture viability. In this work, the relationship between the initial size and weaning success has been studied in wedge sole (Dicologoglossa cuneata). For each age (30, 50, and 70 days after hatching, DAH), two to three sizes were selected, and all were put on the same feeding schedule for 20 days. Each batch (three replicates) was sampled at 1, 10, and 20 days. Specific growth rate (SGR) and survival were compared at the end of the co-feeding period, after 10 days on dry feed only. The best results for survival and growth were found with the smallest larvae, and vice versa. The SGRs and survival rates recorded during the co-feeding period were higher (0.8–15.6 day−1 and 68.3–97.8%) than those from the dry-food phase (0.9–4.7 day−1 and 56.3–66.7%). Successful weaning (survival = 65% and SGR = 9.3 day−1) is possible with 30 DAH larvae (7.6–8.1 mm and 3.9–4.6 mg). In conclusion, the most effective weaning would be possible at 30 DAH, implying significant Artemia savings (25–50%).  相似文献   
9.
10.
From mid-August to mid-September 1998, a dinoflagellate bloom in a shrimp pond near La Paz, Baja California Sur, was studied. Daily samples were taken of phytoplankton, dissolved oxygen, nutrient concentrations, photosynthetic pigments and proteins. The bloom occurred at temperatures of 29.7 to 33.2?°C. High densities of a Scrippsiella-like dinoflagellate (15.9?×?106 cells/L) occurred on the first day of sampling, reaching a peak of 249?×?106 cells/L on Day 13, and declining to 4 to 7?×?106 cells/L by Day 26. Chlorophyll a varied from 8.63 mg/m3 on Day 4 to 141.38 mg/m3 on Day 13. Total nitrogen varied widely (0.2–11.50 μM) while phosphates peaked only once on Day 13 (4.14 μM). Proteins ranged from 523 to 6387 μg/L; the latter value occurred two days after the maximal peak of nitrates and coinciding with the highest level of phosphates. Fertilizers added to the ponds increased nutrient concentration and stimulated phytoplankton growth. In turn, the food supply to cultured shrimp noticeably increased throughout the bloom.  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