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   507篇
  免费   15篇
林业   8篇
农学   20篇
基础科学   4篇
  83篇
综合类   23篇
农作物   28篇
水产渔业   5篇
畜牧兽医   323篇
园艺   10篇
植物保护   18篇
  2023年   7篇
  2022年   5篇
  2021年   9篇
  2020年   13篇
  2019年   9篇
  2018年   8篇
  2017年   15篇
  2016年   7篇
  2015年   6篇
  2014年   11篇
  2013年   24篇
  2012年   22篇
  2011年   28篇
  2010年   22篇
  2009年   17篇
  2008年   15篇
  2007年   21篇
  2006年   24篇
  2005年   18篇
  2004年   24篇
  2003年   13篇
  2002年   22篇
  2001年   20篇
  2000年   22篇
  1999年   27篇
  1998年   9篇
  1997年   5篇
  1996年   2篇
  1994年   5篇
  1993年   3篇
  1992年   9篇
  1991年   10篇
  1990年   10篇
  1989年   11篇
  1988年   6篇
  1987年   5篇
  1986年   5篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
  1980年   2篇
  1979年   3篇
  1974年   1篇
  1973年   1篇
  1971年   2篇
  1970年   3篇
  1969年   4篇
  1968年   5篇
  1966年   2篇
  1961年   1篇
排序方式: 共有522条查询结果,搜索用时 234 毫秒
91.
Foot and mouth disease (FMD) is the most contagious disease of mammals and a major threat to animal husbandry sector. In India, vaccination with the inactivated trivalent (O, A and Asia1) vaccine is one proven way for protecting the livestock from FMD. However, many outbreaks have been reported in different parts of the country. Therefore, present study was aimed at elucidating the effects of genetic and non-genetic factors on FMD viral vaccine-elicited immune response in Hardhenu cattle. The effect of season of vaccination was not consistent. The effect of status of animal was significant for all the pre and post AB titres except for pre AB titre of serotype O and post AB titre of Asia1.The estimates of heritability for response to vaccination were low to high ranging from 0.11 to 0.45. The highest heritability estimate was obtained for serotype O and the lowest for Asia1. The heritability estimates for pre and post AB titres ranged from 0.15 to 0.33. All the pre and post AB titres and responses to vaccination had genetic correlations ranged from high negative to high positive among them. Results of this study highlight the variation in vaccine response which needs to be further exploited on large-scale animal data for better immunization and protection against highly contagious viral vesicular disease of cloven-hoofed animals.  相似文献   
92.
The HYDRUS-ID model was experimentally tested for water balance and salt build up in soil under rice crop irrigated with different salinity water (ECiw) of 0.4, 2, 4, 6, 8 and 10 dS m−1 in micro-lysimeters filled with sandy loam soil. Differences of means between measured (M) and HYDRUS-1D predicted (P) values of bottom flux (Q o) and leachate EC as tested by paired t test were not found significant at P = 0.05 and a close agreement between RMSE values showed the applicability of the HYDRUS-1D to simulate percolation and salt concentration in the micro-lysimeters under rice crop. Potential ET values of rice as obtained from CROPWAT matched well with model predicted and measured one at all ECiw treatments. The model predicted root water uptake varied from 66.1 to 652.7 mm and the maximum daily salt concentration in the root zone was 0.46, 2.3, 4.5, 6.7, 8.4 and 10.2 me cm−3 in 0.4, 2, 4, 6, 8 and 10 dS m−1 ECiw treatments, respectively. The grain production per unit evapotranspiration ( \textWP\textET\texta {\text{WP}}_{{{\text{ET}}_{\text{a}} }} ) value of 2.56 in ECiw of 0.4 dS m−1 treatment declined to 1.31 with ECiw of 2 dS m−1. The \textWP\textET\texta {\text{WP}}_{{{\text{ET}}_{\text{a}} }} reduced to one-fifth when percolation was included in the productivity determination. Similarly, the water productivity in respect of total dry matter production (TDM) was also reduced in different treatments. Therefore, the model predicted values of water balance can be effectively utilized to calculate the water productivity of rice crop.  相似文献   
93.
94.
Probiotics of Lactobacillus acidophilus, Saccharomyces cerevisiae, and Aspergillus niger and three commercial exogenous fibrolytic enzymes (EFE) were tested in vitro to select best source and optimum dose followed by in vivo studies on male buffalo calves. Bacterial (P < 0.001) and protozoal population were increased significantly (P < 0.001) with probiotics and EFE. In vitro dry matter digestibility was more (P < 0.001) on L. acidophilus and then on S. cerevisiae. Dose required for L. acidophilus and S. cerevisiae probiotics was 1 × 109 and 3 × 109 cfu/flask, respectively. Cellulase and xylanase were effective at 4,000 and 12,500 IU/kg DM. In vitro cell wall digestibility was increased (P < 0.001) when probiotics and EFE were used together. Best source and optimum dose of probiotics and EFE were fed to 18 male buffalo calves with concentrate supplement (CS). Calves were randomly divided into three groups either without probiotics and EFE (CG) or with probiotics (EG1) or probiotics combined with EFE (EG2) on wheat straw diet. Organic matter, neutral detergent fiber, and acid detergent fiber digestibility was improved significantly. Average daily weight gain (ADG) and feed efficiency were significantly higher (P < 0.001) in EG2 than EG1 or CG. Final body weight was 4% and 12% and feed efficiency was 2.6% or 1.6% more (P < 0.001) in EG2 compared to CG or EG1, respectively. Fortification of CS with probiotics and EFE together had more impact on FE and ADG in buffalo calves.  相似文献   
95.
96.
97.
98.
An experiment was conducted under simulated condition to study the influence of vermicompost on growth, yield and heavy metal accumulation by chamomile (Matricaria chamomilla), an important essential oil bearing crop grown under simulated condition. Nickel and Cadmium applied at 20?mg?kg?1 soil significantly enhanced the dry matter yield of the crop as compared to the control (no heavy metal). The results also revealed that addition of vermicompost (at 2.5?g?kg?1 soil) enhanced the heavy metal accumulation by chamomile in metal-treated soil. Although a sizeable amount of metals were being translocated to flowers, the essential oil extracted by hydrodistillation of flowers did not contain any heavy metal. Similarly, chemical constituents of the oil of chamomile were within the range of those obtained from chamomile grown under normal soil condition.  相似文献   
99.
Air pollution emissions were not continually monitored in the Upper Silesian Industrial District (USID), southern Poland, and data is only available for the last 20?years. Long-lasting and severe tree ring reductions in pines growing 5-20 km north of the USID area recorded particularly high levels of air pollution emissions in the period 1950-1990. Especially high amounts of reductions and many missing rings were found in the period 1964-1981. At the same time, pines growing 60?km west of the USID do not record deep ring reductions; this proves that the phenomenon is of a regional nature. Increases in infant mortality and lung, bronchial, and tracheal cancer morbidity rates among males were also recorded in the USID during periods of high air pollution. Infant mortality rates increased several years after the tree ring reductions. Therefore, it may be possible to use tree ring reductions as an early indicator of the occurrence of adverse effects on human health.  相似文献   
100.
The effects of seasonal high temperatures on potatoes were investigated under field conditions near Peshawar, Pakistan. Five potato clones (A79196-1, Desiree, DTO-28, LT-1, Russet Burbank) were grown during the spring season at two locations. Canopy development, vine dry weight and tuber dry weight were determined at 13-day intervals, starting 68 days after planting (DAP). Tuber yield was higher in heat tolerant clones compared to heat susceptible clones. Location significantly affected tuber dry weights. Tuber dry weights of Russet Burbank were consistently lower than those of DTO-28. Ground canopy cover of DTO-28 occurred earlier and reached maximum at 75 DAP, compared to 90 DAP for Desiree. DTO-28, because of its high tuber yield under cool as well as hot temperatures, and its relatively early bulking, should be a promising clone for a short duration crop in hotter regions.  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