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   38篇
  免费   0篇
林业   5篇
农学   1篇
  11篇
综合类   3篇
农作物   2篇
水产渔业   10篇
畜牧兽医   6篇
  2023年   2篇
  2022年   3篇
  2021年   2篇
  2020年   3篇
  2019年   3篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2014年   2篇
  2013年   1篇
  2012年   1篇
  2011年   2篇
  2010年   1篇
  2008年   1篇
  2007年   2篇
  2006年   2篇
  2005年   1篇
  2004年   3篇
  2003年   1篇
  2002年   2篇
  2000年   1篇
  1996年   1篇
排序方式: 共有38条查询结果,搜索用时 0 毫秒
21.
The failure of fisheries science to preserve life in the oceans is broadly recognized. Here, we argue that part of this failure is the result of the philosophical basis behind fisheries science. In the middle of the 20th century, synthesizing more than half a century of insights dealing with what they called the 'overfishing problem', British scholars gave birth to some of the first predictive fishery management tools. Although novel for their time, the main objective of the approach was to advise the fishing industry on how to maximize the exploitation of fish resources without jeopardizing the viability of fish populations. Half a century on from these first attempts, we need a wider historical perspective to understand species dynamics, both natural and anthropogenic. We are also aware that there are other benefits society obtains from the ocean than maximum sustainable catches and we need to understand the role of biodiversity in social welfare. Not only should fishing be regarded as an economic activity but also as a planetary-scale human experiment that requires experimental controls for a continuous evaluation of its performance and effects. Here, we present a philosophical approach to the problem, synthesizing material from the different disciplines that we consider should be addressed. A mix of insights may best help to deal with the 'overfishing problem.'  相似文献   
22.
23.
The dynamic water vapour sorption properties of Scots pine (Pinus sylvestris L.) wood samples were studied to investigate the modifying effects of glutaraldehyde. Pine sapwood was treated with solutions of glutaraldehyde and a catalyst (magnesium chloride) to obtain weight per cent gains of 0.5, 8.6, 15.5, and 21.0%, respectively. The sorption behaviour of untreated and treated wood was measured using a Dynamic Vapour Sorption apparatus. The results showed considerable reduction in equilibrium moisture content of wood and the corresponding equilibrium time at each target relative humidity (RH) due to glutaraldehyde treatment. The moisture adsorption and desorption rates of modified and unmodified wood were generally faster in the low RH range (up to approximate 20%) than in the high range. Modification primarily reduced the adsorption and desorption rates over the high RH range of 20–95%. Glutaraldehyde modification resulted in a reduction in sorption hysteresis due to the loss of elasticity of cell walls.  相似文献   
24.

Objectives

This study aimed to define the antimicrobial peptide (AMP) expression pattern of the equine ocular surface and amniotic membrane using a targeted qPCR approach and 3'Tag-sequencing. It will serve as a reference for future studies of ocular surface innate immunity and amniotic membrane therapies.

Procedures

A targeted qPCR approach was used to investigate the presence of orthologs for three of the most highly expressed beta-defensins (DEFB1, DEFB4B, and DEFB103A) of the human ocular surface and amniotic membrane in equine corneal epithelium, conjunctiva, and amniotic membrane. 3'Tag-sequencing was performed on RNA from one sample of corneal epithelium, conjunctiva, and amniotic membrane to further characterize their AMP expression.

Results

Equine corneal epithelium, conjunctiva, and amniotic membrane expressed DEFB1, DEFB4B, and DEFB103A. DEFB103A was expressed at the highest amounts in corneal epithelium, while DEFB4B was most highly expressed in conjunctiva and amniotic membrane. 3'Tag-sequencing from all three tissues confirmed these findings and identified expression of five additional beta-defensins, 11 alpha-defensins and two cathelicidins, with the alpha-defensins showing higher normalized read counts than the beta-defensins.

Conclusions

This study identified AMP expression in the equine cornea and conjunctiva, suggesting that they play a key role in the protection of the equine eye, similar to the human ocular surface. We also determined that equine amniotic membrane expresses a substantial number of AMPs suggesting it could potentiate an antimicrobial effect as a corneal graft material. Future studies will focus on defining the antimicrobial activity of these AMPs and determining their role in microbial keratitis.  相似文献   
25.
26.
Paddy and Water Environment - Optimization of land-use practices of rice cultivation for the mitigation of the most significant greenhouse gas (GHG) emissions from agriculture methane (CH4) and...  相似文献   
27.
28.
Many over‐exploited marine ecosystems worldwide have lost their natural populations of large predatory finfish and have become dominated by crustaceans and other invertebrates. Controversially, some of these simplified ecosystems have gone on to support highly successful invertebrate fisheries capable of generating more economic value than the fisheries they replaced. Such systems have been compared with those created by modern agriculture on land, in that existing ecosystems have been converted into those that maximize the production of target species. Here, we draw on a number of concepts and case‐studies to argue that this is highly risky. In many cases, the loss of large finfish has triggered dramatic ecosystem shifts to states that are both ecologically and economically undesirable, and difficult and expensive to reverse. In addition, we find that those stocks left remaining are unusually prone to collapse from disease, invasion, eutrophication and climate change. We therefore conclude that the transition from multispecies fisheries to simplified invertebrate fisheries is causing a global decline in biodiversity and is threatening global food security, rather than promoting it.  相似文献   
29.
30.
This paper investigates the regional relationships between highflow water chemistry and conifer forest cover in 95 streamsspread over an area of approximately 2000 km2 in Galloway,south-west Scotland, paying particular attention to the use ofdetailed catchment area data. Catchment forest data areextracted from a 30 m resolution tree height map derived fromsatellite imagery; geology data from a digital geology map; andaltitude and slope data from a 50 m resolution Digital TerrainModel (DTM). The results show that over the entire region pHlevels are lower with increasing catchment afforestation whilstaluminium concentrations are higher. Concentrations of sulphate arealso higher with increasing afforestation, which suggests thatconifers play a primary role in increasing the acidity levels ofstreams by exacerbating aerial acid deposition in the entireregion.  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