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   126篇
  免费   20篇
  国内免费   14篇
  8篇
综合类   23篇
农作物   2篇
水产渔业   121篇
畜牧兽医   5篇
植物保护   1篇
  2024年   5篇
  2023年   4篇
  2022年   10篇
  2021年   2篇
  2020年   6篇
  2019年   15篇
  2018年   9篇
  2017年   6篇
  2016年   8篇
  2015年   3篇
  2014年   7篇
  2013年   7篇
  2012年   10篇
  2011年   13篇
  2010年   5篇
  2009年   6篇
  2008年   7篇
  2007年   1篇
  2006年   10篇
  2005年   9篇
  2004年   2篇
  2003年   2篇
  2002年   1篇
  2001年   5篇
  1999年   4篇
  1998年   1篇
  1995年   1篇
  1990年   1篇
排序方式: 共有160条查询结果,搜索用时 15 毫秒
1.
中国深远海养殖发展方式研究   总被引:1,自引:0,他引:1  
在渔业转型发展进程中,发展深远海养殖是突破生态环境和自然资源约束性挑战,实现新时期中国海水养殖业可持续发展的战略方向。基于联合国粮食及农业组织(FAO)关于深远海养殖发展的定义,结合中国海水养殖业发展水平和海域条件,对中国深远海养殖概念进行了界定。提出养殖品种选择、养殖系统构建、养殖海域规划是关系深远海养殖产业稳步有序发展的重要因素。在养殖品种选择方面,应重点考虑经济潜力、适应水温和养殖技术;在养殖系统构建上,分析比较了不同养殖系统应用于深远海养殖的适宜性、安全性和经济性;在养殖海域规划方面,应重点考虑养殖排放、环境承载力和海域条件。  相似文献   
2.
Two novel acoustic transmitter tags intended to reflect feeding behaviours in farmed Atlantic salmon (Salmo salar L.) were developed and tested in this study. Using information from the literature and video recordings of feeding salmon, measurements of swimming depth and motion (acceleration) were identified as two promising sensing principles on which to base the tag development. Video footage and laboratory studies were used to develop corresponding algorithms that translated depth and acceleration measurements into compound parameters reflecting the different aspects that discern feeding activity from other activities. Field tests performed in a sea-farm were used to verify the functionality of the tags, and indicated that both tag types had potential in distinguishing between feeding and non-feeding behaviour. Additionally, both depth- and acceleration-based tags were seen to have applications to fish monitoring and farm management beyond that of observing feeding in salmon, in giving recordings of the vertical swimming behaviour of fish over extended periods of time as well as indications of the activity changes of fish due to external influences. These results suggest that fish telemetry using sensor-based transmitter tags could represent a useful tool in future fish farm management.  相似文献   
3.
Coral aquaculture is viewed as a sustainable method of providing colonies for use in the aquarium trade, pharmacological studies, and coral reef rehabilitation. The production of large, healthy specimens depends on providing conditions that mimic or surpass natural reef environments. Materials with a high degree of variability in physical and chemical properties are utilized as substrates in coral aquaculture, but until fragment–substrate interactions are isolated and independently studied, the possible inhibitory and facilitative effects of each material will remain unclear. To understand potential key roles that substrates can play in coral culture, a comparison was made about the role of various materials on fragment survival and growth. The experiment examined the interactions between isolates of a common scleractinian coral, Galaxea fascicularis, and six commonly used substrates (coral rock, terracotta, polyvinyl chloride, steel, rubber tire, and concrete) and how these affected survival and growth. No differences were observed in the survival, colony size, and polyp production of the resulting microcolonies. The results show that, for G. fascicularis, growth is not affected by substrate type. The results demonstrate the use of a wide variety of materials for the successful aquaculture of scleractinian corals.  相似文献   
4.
关于贝类遗传改良几个问题的讨论   总被引:13,自引:2,他引:13  
张国范 《水产学报》2006,30(1):130-137
贝类大多为雌雄异体,少数种类是雌雄同体,在雌雄异体的种类也有部分个体表现为雌雄同体,而且雌雄异体型贝类还常有性转变现象。养殖贝类大多行体外受精并具有配子量大、子裔数量多等特点。野生型贝类表型方差大,遗传变异水平高。可见,贝类是一群比较独特的动物,其生殖方面的某些特性与作物的共同点甚至超过与高等动物的共同点。因此仅依靠脊椎动物或植物的育种方法,难以解决好贝类的种质改良问题。  相似文献   
5.
海水网箱养殖对近岸环境影响的研究进展   总被引:3,自引:0,他引:3  
郭芳  黄小平 《水产科学》2006,25(1):37-41
近年来,我国的海水网箱养殖业发展迅猛,已成为我国渔业新兴产业的生力军。海水网箱养殖系统作为一种高密度、高投饵的人工养殖生态系统,其输出的废物,残饵、代谢及排泄废物等是引发环境问题的主要污染源,再加上网箱养殖区布局不合理,通常设在水交换率较低的内湾,当养殖容量超出了海域的环境容量,就会引发一系列生态环境问题[1]。本文就海水网箱养殖对环境污染及防治的研究进展进行综述,并提出今后的重点研究方向。1养殖区水质污染网箱养殖对浅海生态系统的影响主要表现为养殖水域营养负荷增加[2]。一般来说,鲑鳟鱼类的网箱养殖,饲料中总氮的…  相似文献   
6.
A periphyton biofiltration system of mariculture effluents was studied to identify ecological processes and management procedures that strongly affect the biofilter functioning, in order to attain optimal biomass production and nutrient removal. The multivariate statistical technique of factor analysis allowed reducing the large amount of data available into three main factors. The first factor, which accounted for 49% of the overall data variability, was herein called “biological activity” as it represents the joint effects on the variables measured of photosynthesis, N and P uptake, respiration and decomposition of organic matter. The second and third factors were “autotrophic biomass density” and “nitrite and phosphate uptake/release balance”, which, respectively, accounted for further 20% and 14% of the data variability. A conceptual model, describing the functioning of the periphyton biofilters, revealed a delicate equilibrium among the different processes, whose understanding help to manage the biofilters towards optimal production of periphytic biomass and nutrient removal. Raising flow rate raised the overall nutrient uptake rate but reduced uptake efficiency and diluted nitrifying particles. A reduced flow rate led to sedimentation of organic particles, decomposition and nutrients re‐mineralization. Apparently, control of water flow and nutrient content, periphyton substrate area and the cleaning of the effluent supply system are key management elements for the operation of a periphyton‐based biofilter system that maximizes both periphyton biomass production and nutrient removal.  相似文献   
7.
福建省海水养殖业生态安全评价   总被引:1,自引:0,他引:1  
以福建省为例,应用PSR模型,从海水养殖业生态环境的系统压力、系统状态、系统响应3个方面筛选出26个指标,在专家打分的基础上,采用层次分析法确定指标权重,从时间尺度上(2003-2012年)评价福建省海水养殖业的生态安全状况及其发展趋势,探究影响福建省海水养殖业生态安全水平的主要原因.结果表明,福建省海水养殖业的生态环境总体呈现越来越好的趋势,但仍然面临较严峻的挑战.  相似文献   
8.
近年来,浙江省海水养殖业迅速增长,2003年、2004年海水养殖产量分别比上一年增加7.9%和1.2%,产量分别为9.184×106t和9.294×106t。但是在养殖规模不断扩大,养殖产量不断增加的同时,养殖生物死亡事故也不断发生,根据《中国渔业生态环境状况公报(2004年),》2004年浙江省发生海水  相似文献   
9.
The mandarinfish, Synchiropus splendidus, is a small, pelagic-spawning enthic dragonet of the western Pacific. Although popular in the marine aquarium trade, little is known of its fishery or biology. All aquarium-trade animals are currently taken from the wild and the impact of heavy collecting is unknown. The specialized and selective nature of the fishery for mandarinfish is described and its potential to disrupt the mating system identified. As a possible alternative to wild capture and as an aid to sustainable exploitation, egg production and early development relevant to mariculture are described, including egg output, embryo, larva and post-settlement development to 30 days, based on live material. Egg output was determined for 40 females and ranged from 12 to 205 eggs. Embryo and larva development were rapid, with settlement occurring within 14 days at 24–26 °C, and at 3.5 mm TL. The swimbladder is retained in adults. Our limited attempts at raising the mandarinfish to settlement were encouraging and suggest an excellent potential for mariculture with implications for both conservation and improved maintenance of fish in captivity. At present, given that this species is difficult to maintain in captivity, it is only suitable for experienced aquarists. Preliminary diet information is provided. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
10.
In coral mariculture, growth is one of the most common ways to track success. However, numerous methods of monitoring coral growth make comparative studies challenging. A literature review of 39 studies from 1982 to 2017 indicated that the most predominant non‐invasive methods used were linear and areal measurement and these were evaluated for their accuracy using nursery‐reared corals. The monthly change in linear and areal growth rates of six coral species (= 215), Pocillopora acuta, Hydnophora rigida, Merulina ampliata, Podabacia crustacea, Echinopora lamellosa and Platygyra sinensis were measured via photogrammetry. We tested whether the planar area of coral colonies can be estimated using three geometric formulas of linear measurements. Based on the literature review, the six types of measurement methods were namely linear, volume, weight, area, count of polyps/branches and calcification, in decreasing order of application. Our results showed that the change in area calculated by geometric mean diameter (GMD) formulas provided the most accurate estimation among the three formulas and was strongly correlated with planar area (R2 ≥ .60; p < .05) for all coral species, except E. lamellosa and Pl. sinensis. However, our findings suggest that it is not ideal to use geometric formulas to estimate the change in area. Instead, we posit that areal photogrammetry represents the simplest yet accurate non‐invasive method for rapid monitoring of extensive areas of corals in situ. Lastly, we discuss the recommendations and limitations for areal photogrammetry.  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