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   745篇
  免费   43篇
  国内免费   30篇
林业   39篇
农学   52篇
基础科学   4篇
  36篇
综合类   275篇
农作物   42篇
水产渔业   15篇
畜牧兽医   302篇
园艺   16篇
植物保护   37篇
  2024年   2篇
  2023年   11篇
  2022年   15篇
  2021年   17篇
  2020年   23篇
  2019年   13篇
  2018年   17篇
  2017年   20篇
  2016年   36篇
  2015年   26篇
  2014年   49篇
  2013年   62篇
  2012年   70篇
  2011年   105篇
  2010年   57篇
  2009年   44篇
  2008年   41篇
  2007年   33篇
  2006年   25篇
  2005年   18篇
  2004年   18篇
  2003年   13篇
  2002年   11篇
  2001年   11篇
  2000年   6篇
  1999年   7篇
  1998年   10篇
  1997年   5篇
  1996年   2篇
  1995年   11篇
  1994年   4篇
  1993年   7篇
  1992年   6篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   5篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1979年   1篇
  1978年   1篇
排序方式: 共有818条查询结果,搜索用时 15 毫秒
101.
A longitudinal study was conducted in Southeast Uganda for 14 months on 640 Zebu cattle kept under natural tick challenge, with a view to identifying clinical features for prediction of seroconversion to Anaplasma marginale, Babesia bigemina and Theileria parva infections. Physical examination, condition scoring and tick counts were undertaken on all cattle every 4 weeks. In addition, 5300 sera were collected and analysed for antibodies against A. marginale, B. bigemina and T. parva infections using the enzyme-linked immunosorbent assay (ELISA). The major clinical features compiled included weight loss, fever (rectal temperature), anaemia (packed cell volume), pallor of mucous membranes, lymph node enlargement, staring coat, diarrhoea and lacrymation. The risk factors included tick challenge at village level, sex, age, Rhipicephalus spp. density and Boophilus spp. density on individual animals. Using a binary logistic regression model, the clinical features and risk factors were analysed. The results suggest that increasing rectal temperature was associated with increased probability for seroconversion to A. marginale, while high level of Rhipicephalus spp. density and increasing packed cell volume (PCV) were significantly associated with reduced probability of seroconversion. Although statistically significant, none of the factors had large effects, with odds ratios (OR) of 0.87, 1.15 and 0.98 for Rhipicephalus spp. density, rectal temperature and PCV, respectively. For B. bigemina infection, a high level of Boophilus spp. density, anaemia and staring coat were significantly associated with increased probability of seroconversion (OR 1.50, 1.78, 1.37, respectively). Presence of lacrymation and old age were associated with reduced probability of seroconversion (OR 0.52, 0.86 respectively). For T. parva infection, lymph node enlargement (OR 1.30) was associated with increased probability of seroconversion, while high Rhipicephalus spp. density and increasing packed cell volume (PCV) were associated with reduced probability of seroconversion (OR 0.68 and 0.98, respectively). In conclusion, presence and intensity of the respective tick vectors for tick-borne diseases, age and clinical features such as anaemia, fever, staring coat, lymph node enlargement and lacrymation are indicators for seroconversion to A. marginale, B. bigemina and T. parva infections in cattle. These indicators for seroconversion could be exploited in the development of decision support tools for clinical diagnosis of tick-borne diseases.  相似文献   
102.
Background: Endocarditis is a rare heart condition with variable clinical expressions in equids. Risk factors for this disease are incompletely understood. Objective: Describe risk factors for endocarditis in equids. Animals: One hundred and fifty‐three equids admitted to Liège University, 9 diagnosed with endocarditis and 144 free from endocarditis but admitted to the hospital with a differential diagnosis including this disease. Methods: Retrospective case‐control study. Results: Equids with endocarditis were significantly younger (mean age = 4.84 ± 5.74 years) than control equids (mean age = 10.8 ± 7.73 years) (P= .01). No sex or breed predisposition was observed. Animals with hyperthermia (odds ratio [OR] = 24.4; confidence interval [CI] = 1.40–428), synovial distension (OR = 13.4; CI = 3.00–59.8), lameness (OR = 6.52; CI = 1.63–26.1), hyperglobulinemia (OR = 26.4; CI = 3.03–229), hypoalbuminemia (OR = 11.4; CI = 1.34–96.8), hyperfibrinogenemia (OR = 9.81; CI = 1.16–82.7), or leukocytosis (OR = 7.12; CI = 1.40–36.4) presented a significantly higher risk of having endocarditis than control horses. The presence of two of the clinical signs mentioned above significantly increased the probability of a diagnosis of endocarditis (P≤ .05). Conclusions and Clinical Importance: Age is associated with equine endocarditis. The diagnostic value of certain clinical signs and abnormalities in blood parameters in this disease are described.  相似文献   
103.
BACKGROUND: The tawny owl (Strix aluco) is a protected species in Italy. Orphaned, injured, and ill owls often are sheltered and treated in rehabilitation centers, where hematologic and biochemical analyses would be helpful to evaluate and monitor the status of their health. OBJECTIVES: The major aim of this work was to assess hematologic and biochemical constituents together with protein electrophoretic fractions in healthy tawny owls. In addition, we compared laboratory methods for determining hemoglobin (Hgb), total protein, and albumin concentrations. METHODS: Heparinized blood samples were collected from 10 clinically healthy adult captive tawny owls between March 2001 and November 2003 for CBC, routine biochemical analysis, and protein electrophoresis. Alternate methods for Hgb (estimation as HCT/3 vs spectrophotometry), total protein (biuret vs refractometry), and albumin (bromcresol green vs electrophoresis) concentrations were compared in 34 samples from 16 unhealthy adult owls and 8 nestlings. RESULTS: Results were reported as mean, median, and range (minimum-maximum). Significant differences and poor concordance were observed between methods for Hgb, total protein, and albumin. CONCLUSIONS: Hematologic and plasma biochemical values in captive tawny owls may be useful in evaluating and monitoring the health of this species in captivity.  相似文献   
104.
兽医临床实例训练是安徽农业大学动物医学专业近几年新开设的一门实践课程。该课程以学校动物医院为实践平台,以提高学生的动手操作技能,增强临床实践能力,培养学生的临床思维能力和初步职业素质为目标,通过在教学过程中不断地实践和完善,探索出一套合理的、先进的教学与考核模式。该模式取得了明显的教学效果,为兽医临床实践教学改革提供了新思维和新方法。  相似文献   
105.
106.
3组16日龄小鸡人工感染以鸡传染性法氏囊病(IBD)病毒,48h后出现临床症状,分别内服三黄白术片,剂量分别为0.375g,0.25g和0.125g,每日2次,连服5日,随后的10日内,治疗组分别死亡13.3%(4/30)、16.7%(5/30)和40%(12/30),而未治疗的对照组死亡53.3%(16/30)。在相对增重上,治疗组分别为73.9%、70.1%和71.1%,而未治疗对照组为25.8%。  相似文献   
107.
药物防治的临床药理学与水产药物学问题   总被引:18,自引:0,他引:18  
阐述了影响水产养殖中药物防治效果的临床药理学的几个重要参数和水产药物学在药物制剂、给药方案、治疗药物的检测和治疗效果等方面存在的问题,及其给水产养殖动物造成的不良后果。并提出了正确用药的原则和方法。  相似文献   
108.
枯草芽孢杆菌防治草莓白粉病的田间试验   总被引:2,自引:0,他引:2  
草莓白粉病是琼海草莓生产中的常发性主要病害,严重影响草莓的生产。琼海草莓种植期间低温、高湿气候情况频发,有利于草莓白粉病的发生。通过不同配方组合发现:枯草芽孢杆菌按4 050 g/hm2用量单独使用,预防草莓白粉病防效达92.09%,发病后混合化学药剂露娜森做治疗,具有防效快、持效期长等优点。  相似文献   
109.
草莓白粉病是琼海草莓生产中的常发性主要病害,严重影响草莓的生产。琼海草莓种植期间低温、高湿气候情况频发,有利于草莓白粉病的发生。通过不同配方组合发现:枯草芽孢杆菌按4 050 g/hm2用量单独使用,预防草莓白粉病防效达92.09%,发病后混合化学药剂露娜森做治疗,具有防效快、持效期长等优点。  相似文献   
110.
采用室内和田间试验,研究了巴山榧树3个地理种群种子形态特征、种子萌发特性及幼苗生长规律.结果表明,巴山榧树种子形态特征在种群内和种群间均存在一定程度的变异,重庆南川种群种子变异较大,甘肃武都种群相对较小;3个种群种子大小顺序表现为,甘肃武都>四川万源>重庆南川,长度、宽度和重量在种群间差异显著或极显著,长宽比在重庆南川种群和甘肃武都种群阃差异显著,重庆南川种群种子在形状上趋向椭圆形,甘肃武都种群种子则更趋圆球形.巴山榧树种子具有休眠现象,萌发率较低;1年生幼苗苗高呈“S”型曲线增长;3个种群种子萌发率、幼苗苗高与种子大小顺序表现一致,种子大小对种子萌发和幼苗生长有明显影响.应加强巴山榧树的保护和繁育.  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