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   457篇
  免费   24篇
  国内免费   32篇
林业   13篇
农学   23篇
基础科学   9篇
  47篇
综合类   159篇
农作物   14篇
水产渔业   68篇
畜牧兽医   168篇
园艺   5篇
植物保护   7篇
  2024年   2篇
  2023年   3篇
  2022年   15篇
  2021年   18篇
  2020年   14篇
  2019年   11篇
  2018年   12篇
  2017年   14篇
  2016年   10篇
  2015年   14篇
  2014年   19篇
  2013年   27篇
  2012年   32篇
  2011年   25篇
  2010年   24篇
  2009年   42篇
  2008年   26篇
  2007年   33篇
  2006年   46篇
  2005年   17篇
  2004年   12篇
  2003年   10篇
  2002年   6篇
  2001年   7篇
  2000年   7篇
  1999年   7篇
  1998年   10篇
  1997年   9篇
  1996年   10篇
  1995年   4篇
  1994年   1篇
  1993年   9篇
  1992年   2篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
排序方式: 共有513条查询结果,搜索用时 31 毫秒
101.
农机管理部门要通过有效的管理方法,充分发挥农业机械在农业生产过程中的重要作用,促进农业和农村经济健康、稳定、持续发展。文章分析了基层农机管理服务中存在的问题,并提出对策建议。  相似文献   
102.
喷播植草生态治理技术   总被引:1,自引:0,他引:1  
针对我国“三北”地区的各种立地,如风剥较重的干旱沙丘,退化草地、需退耕还草地、重盐碱地、河堤陡坡、废垃圾场等,结合本单位工作各地工作经验,吸收现阶段 技术和草种品种资源,总结了适地适草的生态治理技术,并力求在保持生态环境改善的同时,兼顾经济产业的形成,突出阐明了不同立地正确选择相应的草种及其品种的技术关键。  相似文献   
103.
浅谈贵南县草产业   总被引:1,自引:0,他引:1  
随着西部大开发的不断深入,西部地区已进入了快速发展的新时期,面对有利的形势和良好的历史机遇,对贵南县草产业的发展思路、存在的问题等做出调整,综合贵南实际,分析和探讨今后发展的思路、对策及措施。  相似文献   
104.
通过草鱼苗口服疫苗特异化饵料,草鱼获得免疫抗体,接种100d 后,在病原的攻击下,免疫组比对照组有明显的抗病性,相对保护力在有效免疫浓度下可达67% ~89% 。  相似文献   
105.
本软件综合运用各种最新的信息技术以及主动武网关技术,将无线通讯网、固定电话网和互联网络连接在一起,实现信息的无缝跨接,拓宽了互联网络上应用系统的服务范围.农业专家或农技推广员利用本软件可以更加方便、快捷地为基层农户提供信息服务,有效的解决了基层农户信息传递的"最后一公里问题".  相似文献   
106.
Recent systematic reviews have highlighted the lack of quality information with respect to the epidemiology of equine laminitis. The objectives of this study were to identify in Denmark, the risk factors for new (i.e., not believed to have suffered from laminitis previously) cases of laminitis (NL) and to look at the outcome and incidence of repeated episodes of laminitis in these animals as well as those which had previously suffered an episode of laminitis (i.e., chronic cases) over the following 12 months. Information was obtained from 110 veterinary diagnosed cases of laminitis (69 new and 41 chronic) and 80 control animals (the next nonlaminitic horse/pony seen by that participating practice). All animals were followed for up to 1 year. Univariable and multivariable conditional logistic regression was conducted for the NL case-control pairs. Variables were retained within the final multivariable models if the likelihood ratio P value was <.05. There was no association between sex or gender and laminitis. A recent change of grass, being on what was considered high-quality grass and being a cold-blooded type, <149 cm (i.e., Shetland, Fell, Welsh, or Dartmoor pony, Icelandic horse, Norwegian fjords, or a mix of these breeds) were all significant risk factors for laminitis. Although cresty neck score and body condition score were significantly associated with NL at the univariable screening stage, they were found to be confounders of breed and each other during the multivariable model building process. Other factors such as weight and estimated starch intake were not found to be significant. Thirty-three percent of all the laminitis cases had been humanely destroyed within 12 months of diagnosis, mainly for laminitis-associated reasons, compared with only 7.5% of the controls (none for laminitis associated reasons). This study confirms the importance of grass turnout and breed on laminitis risk. Horses in work at the time of diagnosis as well as those diagnosed in the winter and spring were more likely to be humanely destroyed within the next 12 months than those not in work or diagnosed in the autumn and summer.  相似文献   
107.
Adams  P.R.  Beadle  C.L.  Mendham  N.J.  Smethurst  P.J. 《New Forests》2003,26(2):147-165
Interference by an introduced grass, Holcus lanatus L. (Yorkshire fog grass) in a young E. globulus (Tasmanian blue gum) plantation was investigated. The objectives were to determine (1) the critical period of competition, and (2) how the timing and duration of competition was related to the interaction between tree growth and resource availability. This was investigated during the first two years of establishment. Weed interference was severe with height and diameter growth of weedy trees being 52% and 40% of weed-free trees, respectively, at age two years. Most growth losses occurred during the first year. The critical period of weed interference was from planting to age 18 m and effective weed control was required for this period to maximise tree growth potential. The application of nitrogen to weedy trees promoted a significant growth response suggesting that competition for nitrogen was occurring. There was no significant response to level of irrigation. The use of critical period analysis is discussed.  相似文献   
108.
After tropical forest disturbance, mycorrhizal inoculum could be insufficient. Increasing mycorrhizal density through inoculum addition is then crucial for successful regeneration of deforested lands. Greenhouse bioassays were set up to determine the effectiveness of native arbuscular mycorrhizal fungi in soils from different disturbance stages on the growth of three important timber species, Terminalia superba, Distemonanthus benthamianus, and Entandrophragma utile. Soils were collected from late and early successional forest stands, fields of food crops, fallow of Chromolaena odorata, skid trails, bare soil landings, and landings with the pioneer tree Musanga cecropioides. These soils were used to grow seedlings without or with addition of an inoculum collected under the grass Paspalum conjugatum. The extent to which seedlings responded to indigenous inoculum and inoculum addition varied with tree species and with mycorrhizal inoculum potential. After inoculum addition, Terminalia strongly increased root colonization with a small increase in shoot dry weight and Distemonanthus hardly increased root colonization but showed a strong increase in shoot dry weight. Entandrophragma increased both root colonization and shoot dry weight. Plant biomass was lower in soils with low inoculum potential such as late successional stands, skid trails, and both kinds of landings; the mycorrhizal inoculation effect was then large. Plant biomass was high in agricultural fields and fallow; mycorrhizal inoculation effect was sometimes even negative. These data indicate that low inoculum might limit plant re-establishment after disturbance and that mycorrhizal inoculation has a potential for improving seedling establishment on deforested land.  相似文献   
109.
据多年的足球场草坪建植经验,总结长江下游地区足球场草坪建植的关键技术是:选用适宜草种、精整场地、适时播种、精细管理。  相似文献   
110.
桃园林下对白花三叶草、紫云英、大巢菜、多年生黑麦草和蚕豆5种植物进行了栽培试验。结果表明:5种植物秋季种子播种出苗后至第二年5月上旬地上部生物量达到高峰,其中白花三叶草、大巢菜和紫云英的地上部生物量可达100 t/hm~2以上;5种植物对杂草均有一定的抑制作用,白花三叶草、大巢菜和紫云英对杂草的抑制作用明显,春季时对禾本科和阔叶杂草的抑制率均达80%以上;桃园种植生草植物后蜜蜂数量普遍增加,其中紫云英种植区蜜蜂数量增幅最高,达1 210.0%。综合其相对电子传递速率、光能利用效率和半饱和光强等参数分析,蚕豆、白花三叶草和紫云英较适宜于桃园林环境下栽培。  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