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   35篇
  免费   18篇
林业   2篇
  1篇
综合类   4篇
农作物   1篇
水产渔业   28篇
畜牧兽医   7篇
园艺   1篇
植物保护   9篇
  2022年   1篇
  2021年   3篇
  2020年   3篇
  2019年   3篇
  2018年   6篇
  2017年   5篇
  2016年   5篇
  2015年   4篇
  2014年   4篇
  2013年   3篇
  2012年   2篇
  2011年   1篇
  2010年   2篇
  2009年   2篇
  2007年   2篇
  2005年   1篇
  2004年   1篇
  2002年   1篇
  1998年   1篇
  1994年   2篇
  1993年   1篇
排序方式: 共有53条查询结果,搜索用时 453 毫秒
21.
22.
During the ascendency of ethology, the study of animal behaviour contributed to taxonomic and phyletic issues, but the approach faded in parallel with the waning of systematic studies in general. Systematics and particularly phylogeny has experienced a resurgence with the advent of molecular tools. The understanding of behavioural evolution has benefited from molecular phylogenies. Behaviour's reciprocal contribution, however, currently lies chiefly in resolving the validity of species designation of allopatric species and in potentially helping in the overall classification of species. I review and evaluate the experimental methods favoured in seeking behavioural isolating mechanisms, and the challenge to the species concept when gene trees and species trees disagree. The dynamic situation in the Great Lakes of Africa offers under‐exploited opportunities to test whether behavioural isolating mechanisms evolve in the absence of secondary contact. Given that behaviour is more immediately responsive to changes in the physical and biological environment, behaviour may be the single most salient adaptive feature in speciation events. The species concept is viewed as a fuzzy but nonetheless useful set.  相似文献   
23.
华山松大小蠹对9种植物挥发物的EAG和行为反应   总被引:1,自引:0,他引:1  
选取5种非寄主挥发性化合物水杨醛、壬醛、三氯乙烯、二氯甲基甲醚和顺-3-己烯-1醇,4种寄主挥发性化合物β-蒎烯、(+)-3-蒈烯、β-石竹烯和(+)-α-蒎烯,应用触角电位仪和Y型嗅觉仪初步研究了华山松大小蠹成虫对这9种化合物的EAG反应和趋向反应。结果表明:雌虫对三氯乙烯、(+)-3-蒈烯和β-石竹烯,雄虫对壬醛、二氯甲基甲醚、(+)-3-蒈烯和(+)-α-蒎烯有明显的EAG反应;β-蒎烯、(+)-3-蒈烯和(+)-α-蒎烯对华山松大小蠹雌成虫有较强的引诱作用;三氯乙烯对雄成虫有较高的引诱率,且显著高于对雌成虫的引诱率。试验结果可为华山松大小蠹的行为控制技术研究提供借鉴。  相似文献   
24.
25.
Abstract –  Scotland is a stronghold for Arctic charr, with about 200 freshwater, wholly loch-resident populations, most of which have yet to be studied. To date, no anadromous populations or individual sea-run charr, have been reported. In Scotland, most Arctic charr spawn in stillwater, during autumn and early winter (September to January), with only one population spawning in spring. Spawning in running water does occur, but has been regarded as rare. This paper examines the status of stream spawning of charr in Scotland, describing instances from 10 populations, although two of these are now extinct. Most stream-spawning charr migrate relatively short distances to running water and construct redds in gently flowing water. The longest recorded migration occurs in Loch Insh, Speyside, with fish travelling 15 km within the River Spey. Information on the extent of stream spawning is essential to help conserve the rich phenotypic and genetic diversity of our remaining charr populations.  相似文献   
26.
Abstract

In-cage reaction tests, the open field test and daily activity in the home cage were used to assess the effect of the internal design and location of cages on the behaviour of juvenile blue foxes (Alopex lagopus) during the growing season. The inclusion of nest boxes or resting platforms affected the behaviour of farmed blue foxes, but to a lesser extent than did the location of the animal in the cage row, i.e. the environment outside the cage itself. This study demonstrated that the actual environment in which the farm foxes live may be far larger than the cage interior itself, and that attempts to improve housing design should take into consideration the environment outside the cage to a greater extent than has heretofore been the case.  相似文献   
27.
28.

Objective

To study the effect of alternating the order of midazolam and alfaxalone administration on the incidence of behavioural changes, alfaxalone induction dose and some cardiorespiratory variables in healthy dogs.

Study design

Prospective, randomized, controlled, clinical trial.

Animals

A total of 33 client-owned dogs undergoing elective procedures.

Methods

Following intramuscular acepromazine (0.02 mg kg?1) and morphine (0.4 mg kg?1) premedication, anaesthesia was induced intravenously (IV) with a co-induction of either midazolam (0.25 mg kg?1) prior to alfaxalone (0.5 mg kg?1; group MA), or alfaxalone followed by midazolam at identical doses (group AM). The control group (CA) was administered normal saline IV prior to alfaxalone administration. Additional alfaxalone (0.25 mg kg?1 increments) was administered as required in all groups until orotracheal intubation was possible. Changes in behaviour, quality of induction, ease of intubation and incidence of adverse events at induction were recorded. Heart rate (HR), respiratory rate (fR) and systolic arterial blood pressure (SAP) were measured before treatments (baseline values), 30 minutes after premedication and at 0, 2, 5 and 10 minutes postintubation.

Results

The incidence of excitement was higher in group MA compared with groups CA (p = 0.005) and AM (p = 0.013). The mean induction dose of alfaxalone was lower in group AM compared with group CA (p = 0.003). Quality of induction and ease of intubation were similar among groups. Mean HR values decreased after premedication and increased after alfaxalone administration in all groups. Mean SAP values were similar between groups. The number of animals that required manual ventilation was higher in the MA group.

Conclusions and clinical relevance

Despite a lower occurrence of adverse events at induction in group AM compared with group MA and a reduction of alfaxalone dose requirement in group AM compared with group CA, the use of an alfaxalone–midazolam co-induction does not seem to produce any cardiovascular or respiratory benefits in healthy dogs.  相似文献   
29.
30.
The UK coastal trap fisheries target two key species, European lobster Homarus gammarus (L.) and brown crab Cancer pagurus L. Their stock status is assessed periodically using size‐based, yield‐per‐recruit analysis. Fishery trends are described using landings and, where available, effort data to estimate catch per unit of effort (CPUE), nominally proportional to abundance. Despite being caught together, assessments assume that concurrent capture of these species does not distort their individual CPUE estimates. Here, an in situ experiment tested impacts of inter‐specific and intra‐specific interactions by pre‐loading baited traps with different species and observing subsequent catches. Pre‐loaded European lobster significantly reduced brown crab catches, whereas, other species produced no such effects. The findings highlight the likely inconsistency of using CPUE as an index of abundance if landings data originate from a mixed‐species fishery in which species interactions and targeting behaviour of fishers are unknown or un‐quantified.  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