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   69篇
  免费   6篇
  国内免费   1篇
林业   6篇
农学   2篇
基础科学   1篇
  8篇
综合类   4篇
农作物   1篇
水产渔业   41篇
畜牧兽医   10篇
园艺   3篇
  2021年   1篇
  2020年   2篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2016年   4篇
  2015年   1篇
  2014年   3篇
  2013年   7篇
  2012年   5篇
  2011年   3篇
  2010年   5篇
  2009年   2篇
  2008年   2篇
  2007年   5篇
  2006年   3篇
  2005年   3篇
  2004年   2篇
  2003年   6篇
  2002年   3篇
  2001年   6篇
  2000年   4篇
  1999年   2篇
  1998年   1篇
  1997年   1篇
  1983年   1篇
排序方式: 共有76条查询结果,搜索用时 15 毫秒
1.
2.
Chromosome compositions of seven lines, derived from hybrids between a wheat cultivar and the wheat-Thinopyrum intermedium addition line Z6, with barley yellow dwarf virus (BYDV) resistance, were determined by genomic in situ hybridization, cytogenetic and SSR assays. The results showed that line N522 was a disomic addition line, lines N420 and N439 were 2Ai-2(2B) chromosome substitution lines, lines N431 and N452 were 2Ai-2(2D) chromosome substitution lines, line N523 was a 2Ai-2S(2D) ditelosomic substitution line, and line N530 was a double ditelosomic line with the mitotic chromosome number of 2n = 40 + 4t. One pair of telosomes in line N530 lacked several proximal SSR markers of chromosome 2AS, but possessed certain terminal markers, which were consistent with an acrocentric structure, and the other pair of chromosome arms were presumably 2Ai-2S telosomes with BYDV-resistance. These wheat-Th. intermedium lines provide useful genetic resources for developing alien chromosome translocation lines.  相似文献   
3.
To analyze the differences in the status and processes of nitrogen saturation in Japan and northeastern United States, we examined the hydrobiogeochemistry of nitrogen of forested watersheds in these regions. Two distinct differences were found between watersheds in Japan compared with those in US. 1) In Japanese watersheds, marked decreases of NO3 ? concentration in surface waters during the summer growing season were not found and NO3 ? concentrations sometimes increased especially in the summer at nitrogen saturated sites. This contrast with watersheds in US where decreases in NO3 ? concentration during the summer are commonly observed except those watersheds in advanced stages of nitrogen saturation. These differences in NO3 ? concentration relationships can be attributed to climatic differences, with Japan having high precipitation and high discharge during the summer, while in many regions of North America lowest discharges are found in the summer. The climatic regime in Japan leads to high rates of mineralization and the rapid transport of NO3 ? to streams in summer. 2) Japanese watersheds, even those with high NO3 ? concentrations in surface waters, show little evidence of acidification. This is in contrast to sites in US where increased NO3 ? concentrations, especially during episodic events, result in surface water acidification.  相似文献   
4.
Many salmonids have become at risk of extinction. For teleosts whose eggs cannot be cryopreserved, developing techniques other than egg cryopreservation to save genetic resources is imperative. In this study, spermatogonia from rainbow trout were intraperitoneally transplanted into newly hatched sterile triploid masu salmon. Transplanted trout spermatogonia underwent spermatogenesis and oogenesis in male and female recipients, respectively. At 2 years after transplantation, triploid salmon recipients only produced trout sperm and eggs. With use of these salmon as parents, we successfully produced only donor-derived trout offspring. Thus, by transplanting cryopreserved spermatogonia into sterile xenogeneic recipients, we can generate individuals of a threatened species.  相似文献   
5.
对厚层及均匀平铺载荷条件下稻谷和糙米的微波干燥过程中的能量效率问题进行了研究。根据本研究的实验数据,如果干燥方法和工艺安排合理,微波干燥稻谷和糙米可达到较高的能量效率,甚至可达到高于传统干燥方法。在微波干燥过程中安排一定的间歇时间以发挥照射后期作用、间歇照射作用或缓苏作用,可以有效地提高微波干燥过程中的能量效率。有2h间歇的干燥工艺的能量效率是没有间歇的干燥工艺的能量效率的5倍。载荷形式对微波干燥过程中的能量效率影响也较大。微波干燥中建议采用薄层载荷形式。  相似文献   
6.
7.
A total of 80 free-roaming dogs on Okinawa Island, Japan, were examined for Babesia infection using the polymerase chain reaction (PCR) and sequence analysis. Of 80 samples, 12 were positive in a Babesia genus-specific PCR. Consequent species-specific PCR for B. canis and B. gibsoni revealed that 5 (6.3%) and 7 (8.8%) dogs were infected with B. canis and B. gibsoni, respectively. Sequence analysis of the PCR products revealed that the 18S rRNA gene sequence of B. canis detected from dogs in Okinawa was very close to B. canis vogeli with sequence similarity of 99.94%.  相似文献   
8.
It is known that soil property varies along the slope. It suggests that soil solution chemistry also differs topographically. To determine the variation in soil solution chemistry within one watershed, soil solution chemistry at the different positions of the slope was investigated. Soil N transformation changed along the slope. NH4 + ratio to inorganic N (NH4 + + NO3 ) increased upslope. The tendency was verified by laboratory incubation. After incubation most of the mineralized N was nitrified at the lower part of the slope, while little nitrification occurred at the upper part of the slope. At the ridge and the backslope inorganic N form in soil solution was concomitant with inorganic N form by incubation. At the ridge NH4 + was predominant form in soil solution, at that time major anion was sea salt originated Cl. From this, soil solution chemistry seems to be regulated by the external nutrient source at the ridge. In the second year of lysimeter installation NO3 concentration increased in both sites and the ratio of NH4 + to inorganic N decreased. It was considered due to the effect of lysimeter installation. The lag time and the magnitude of NO3 increase were different between the ridge and the backslope. It would be related with soil N transformation in pre-disturbance. The influence of disturbance were shown in other solute concentrations of soil solution.  相似文献   
9.
The chemistry of runoff waters from 13 forested watersheds in six regions (four regions from Japan, one from southern China and one from northern Thailand) was evaluated. The Cl concentrations in runoff waters were higher in those watersheds which had closed canopies and were nearer to the ocean. The NO3 concentrations were higher in those watersheds having the developed soils and high moisture conditions, but were lower in tropical and subtropical regions for those watersheds which had high rates of nitrogen uptake and for watersheds with large areas of saturated soils. The SO4 2− concentrations were affected by SO4 2− adsorption properties of the soils: at Shibecha, Jiulianshan, and Chiang Mai with high adsorption capacities SO4 2− concentrations in streams were low. High SO4 2− concentrations were found at Mt. Hiei and Kagawa due to the weathering of sulfur minerals and high levels of atmospheric sulfur deposition. Within regions SO4 2− concentrations were inversely related to NO3 concentrations. A comparison among the watersheds suggested H+ consumption in deeper soil that increased pH and HCO3 concentrations of the runoff waters of some watersheds. Anion concentrations increased with low H.I. (Humidity Index) values suggesting that dry conditions increased concentrations due to high rates of evapotranspiration.  相似文献   
10.
Fisheries Science - Tidal flats are ecologically important as they support a large community of animals (e.g., crabs, mollusks, and polychaetes) and restore water quality. However, information...  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