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   19篇
  免费   0篇
农学   2篇
  7篇
综合类   2篇
农作物   5篇
畜牧兽医   3篇
  2021年   4篇
  2015年   1篇
  2014年   1篇
  2013年   5篇
  2011年   1篇
  2009年   1篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2004年   1篇
  1998年   1篇
  1994年   1篇
排序方式: 共有19条查询结果,搜索用时 31 毫秒
1.
Tick-borne diseases are often encountered in canine clinical practice. In the present study, a molecular epidemiological survey of dogs in Japan was conducted to understand the prevalence and geographical distribution of Babesia spp., Hepatozoon spp., Ehrlichia spp. and Anaplasma spp. Pathogen-derived DNA in blood samples obtained from 722 dogs with a history of exposure to ticks and/or fleas was examined by PCR. The prevalence of Babesia gibsoni, Babesia odocoilei-like species, Hepatozoon canis and Ehrlichia spp./Anaplasma spp. was 2.4% (16/722), 0.1% (1/722), 2.5% (18/722) and 1.5% (11/722), respectively. While B. gibsoni and Ehrlichia spp./Anaplasma spp. were detected in the western part of Japan, H. canis was detected in Tohoku area in addition to western and central parts of Japan.  相似文献   
2.
通过温室盆栽试验 ,分析和探讨了三个水平的土壤水分条件对分蘖期和成熟期收获的旱稻(OryzasativaL .)生物量累积、水分利用率 (WUE)、植株不同部位的碳同位素识别值 (CID)的影响 ,并了解了它们之间的相互关系。水分条件包括 :饱和含水量 (W1 )、饱和含水量的 70 %(W2 )、饱和含水量的 4 0 %(W3)。结果表明当土壤水分条件从W1降低到W2时 ,分蘖期收获的生物量降低 4 5 %左右 ,成熟期收获的生物量降低 1 6 %~ 1 9%;而当从W1降低到W3时 ,分蘖期收获的生物量降低 73%左右 ,成熟期收获的生物量降低 5 5 %~ 5 7%。然而 ,根据地上部干重计算而来的WUE(WUE 地上部 )和根据全株干重计算而来的WUE(WUE 全株 )则随土壤含水量的降低而增加 ,其增幅在分蘖期为 0 .0 7~ 0 .2 8gkg-1 ,在成熟期为 0 .0 7~ 0 .4 5gkg-1 。植株的CID值变幅为 1 7.0~ 2 0 .6 ,但植株不同部位间差别显著 ,分蘖期收获的样品CID值从小到大的顺序为 :根 <最近完全伸展叶 <叶芽 <茎秆 ;而成熟期收获的样品CID值从小到大的顺序为 :籽粒 <根 <茎秆 <旗叶。随着土壤含水量的降低 ,植株所有部位的CID值亦显著减小。叶部的CID值与WUE 地上部(和WUE 全株 )之间呈一致的负相关关系。  相似文献   
3.
A method for HPLC determination of phycocyanin in phytoplankton samples using gelchromatography with a fluorescence detector was developed to examine the use of phycocyanin as an index of the appearance and progress of cyanobacterial blooms in highly eutrophic lake. At least two types of phycocyanin with different molecular weights, each spectroscopically different from phycoerythrin and allophycocyanin, were found in natural phytoplankton samples. Changes in phycocyanin concentrations were clearly coupled to changes in chlorophyll-a concentrations during June to October while cyanobacterial blooms were occurring. The chlorophyll-a to phycocyanin relationship was linear at chlorophyll-a concentrations of less than 250 μg L?1. The relationship between cyanobacterial carbon and phycocyanin concentration was also linear, suggesting that phycocyanin content may be a useful index of cyanobacterial biomass in highly eutrophic lakes where large cyanobacterial blooms occur.  相似文献   
4.
Paddy and Water Environment - Climate change is expected to exacerbate damage to agricultural production from natural disasters. Examination of measures to adapt to the damage represents an urgent...  相似文献   
5.
The purpose of this study was to measure the economic value of the multifunctionality of agriculture and rural areas based on a more realistic assumption than that adopted in previous studies. Willingness to pay (WTP) for implementing a policy that would maintain a level of multifunctionality corresponding to a 20% decrease in the farmland area in Japan was measured by the double-bounded dichotomous choice contingent valuation method (CVM). According to a country-wide survey, the overall median WTP was 4,144 yen per household annually. The multifunctionality of agriculture and rural areas was classified into eight functions. The WTP for each of these functions was calculated taking into account the ratings assigned to the functions by the respondents. The WTP was 649 yen for flood prevention, 505 yen for recharging groundwater, 642 yen for water environment conservation, 445 yen for soil erosion prevention, 579 yen for organic resource utilization, 394 yen for the development of favorable landscapes, 290 yen for recreation and relaxation, and 641 yen for wildlife protection.  相似文献   
6.
The histology and immunohistochemistry of pleomorphic and conventional epithelioid mesotheliomas were examined. The former was detected in two young calves aged 2 and 4 months and was characterized by pleomorphic and atypical cells with decreased expression of cytokeratin 7 (CK7). In contrast, the latter was found in a 31-month-old heifer, consisting of tumor cells uniform in size and shape with CK7 expression in nearly all cells. Production of collagen by tumor cells was demonstrated in both histological types, and was considered to be characteristic of bovine epithelioid mesothelioma. Pleomorphic mesothelioma is far more pleomorphic and mitotically active than conventional mesothelioma, and its normal counterpart may be immature mesothelial cells with high proliferation potential, which exist in fetal life and early calfhood.  相似文献   
7.
Wick samplers could be used for measurements of solute transport. Water collection efficiency of wick samplers, defined as the volume of water collected by a sampler divided by the water flux from the root zone, should be close to 100%. We used three wick samplers differing in wall height in Hydric Hapludands under constant rainfall intensity and examined the effects of the rainfall intensity and wall height on the water collection efficiency based on experimental data and a numerical analysis. The water collection efficiency of wick samplers increased with the rainfall intensity and wall height because the increase in both rainfall intensity and wall height resulted in a distribution of the total potential inside the wick sampler close to that outside the wick sampler. Furthermore, the ratio of the cross-sectional area of the drain hole to that of the cylinder must be taken into account in the design of a wick sampler.  相似文献   
8.
9.
Of the plethora of studies that discuss requirements for successful irrigation management, few pay close attention to what actually happens when the supply of water becomes extremely low. Such an oversight in the literature is unfortunate, because this is precisely when management matters. To understand what separates success from failure in irrigation management at times of critical water shortages, the authors conducted emergency fieldwork in February 2010 along four major irrigation channels in a drought-stricken rice-growing area within the Chinese province of Yunnan. Separately, satellite images of the four villages dated February 2009 and February 2010 were jointly analysed to produce a novel indicator for a village’s success in water management. Called the in-crisis delivery rate, this indicator compares water delivery between normal and drought years and directly evaluates performance in water management during crisis periods. The results led to an unexpected discovery that, contrary to common expectations, the only village of the present study that deployed a traditional earthen water channel secured substantially more water throughout the drought period than those with concrete-lined channels. It is hypothesised that the labour intensive, rather than capital intensive, nature of repair work of the earthen channel enabled flexible operations, and hence had the comparative advantage under a skilled management team. This result confirms the importance of daily maintenance work, which tends to occur less often after modernisation of water paths.  相似文献   
10.
Abstract

Denitrification products nitrous oxide ((N2O) and nitrogen (N2)) were measured in three flooded soils (paddy soil from Vietnam, PV; mangrove soil from Vietnam, MV; paddy soil from Japan, PJ) with different nitrate (NO3) concentrations. Closed incubation experiments were conducted in 100-mL bottles for 7 d at 25°C. Each bottle contained 2 g of air-dried soil and 25 mL solution with NO3 (concentration 0, 5 or 10 mg N L?1) with or without acetylene (C2H2). The N2O + N2 emissions were estimated by the C2H2 inhibition method. Results showed that N2O + N2 emissions for 7 d were positively correlated with those of NO3 removal from solution with C2H2 (R2 = 0.9872), indicating that most removed NO3 was transformed to N2O and N2 by denitrification. In PJ soil, N2O and N2 emissions were increased significantly (P < 0.05) by the addition of greater NO3 concentrations. However, N2O and N2 emissions from PV and MV soils were increased by the addition of 0 to 5 mg N L?1, but not by 5 to 10 mg N L?1. At 10 mg N L?1, N2 emissions for 7 d were greater in PJ soil (pH 7.0) than in PV (pH 5.8) or MV (pH 4.3) soils, while N2O emissions were higher in PV and MV soils than in PJ soil. In MV soil, N2O was the main product throughout the experiment. In conclusion, NO3 concentration and soil pH affected N2O and N2 emissions from three flooded soils.  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