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101.
This study evaluated the effects of three levels of loading density (200, 300 and 400 g L−1) and four levels of duration (1, 3, 6 and 9 h) on the mortality, plasma cortisol and chloride levels and growth of rohu Labeo
rohita fingerlings in a transport simulation. While total immediate mortality was low (4–12%), delayed mortality was high (27–49%).
Initial capture and handling were found to constitute the most stressful phase as indicated by elevated plasma cortisol. The
levels of cortisol continued to rise at 6 and 9 h after transport, with the highest level observed at 9 h after transport.
The level of plasma chloride fell after transport across all density levels and treatment durations. Specific growth rate
(SGR, %/day) and total bacterial density (cfu/g) were not different between and within treatments, and between treatments
and the controls. This study demonstrates that transport has a profound effect on the stress responses of rohu fingerlings.
Although the level of immediate mortality was low, the higher level of delayed mortality has serious implications in terms
of production inefficiency for grow-out farmers. 相似文献
102.
103.
In 1992 and 2002, investigations on the water quality and hydrology were carried out in a small agricultural catchment where
swine waste was stored in earthen waste storage. The in-stream nitrogen loads and the nitrogen inputs on a sub-catchment scale
were estimated and compared between 1992 and 2002. For the entire catchment, the estimated nitrogen inputs increased from
22.5 to 32.9 ton year−1 (from 406 to 594 kg ha−1 year−1), whereas the nitrate nitrogen concentration at the outlet was constant—27 mg l−1. In a sub-catchment (area C) with earthen waste storages, the nitrate nitrogen concentrations at the outlet were high, 42–51 mg l−1. In a sub-catchment (area A) with an earthen waste storage, which was not in service since 1990, although the nitrogen inputs
were maintained at 390 kg year−1 (53 kg ha−1 year−1), the nitrate nitrogen concentrations at the outlet decreased from 26 to 4.9 mg l−1. With assuming that the nitrogen transport rates for sources except swine waste are equal to the rates estimated for a sub-catchment
without earthen waste storage, the in-stream nitrogen loads for area A were estimated to decrease from 1,334 to 94 kg year−1 and the transport rates for area A were estimated to decrease from 3.95 to 0.73. These results suggest that the effluent
from earthen waste storage has affected surface water quality two years after the storage was out of service and its effect
largely decreased after a decade. 相似文献
104.
105.
Layered fabric systems with electrospun polyurethane fiber web layered on spunbonded nonwoven were developed to examine the
feasibility of developing protective textile materials as barriers to liquid penetration using electrospinning. Barrier performance
was evaluated for layered fabric systems, using pesticide mixtures that represent a range of surface tension and viscosity.
Air permeability and water vapor transmission were assessed as indications of thermal comfort performance. Protection performance
and air/moisture vapor transport properties were compared for layered fabric systems and existing materials for personal protective
equipment (PPE). Layered fabric systems with electrospun nanofiber web showed barrier performance in the range between microporous
materials and nonwovens used for protective clothing. Layered fabric structures with the web area density of 1.0 and 2.0 g/m2 exhibited air permeability higher than most PPE materials currently in use; moisture vapor transport was in a range comparable
to nonwovens and typical woven work clothing fabrics. Comparisons of layered fabric systems and currently available PPE materials
indicate that barrier/transport properties that may not be attainable with existing PPE materials could be achieved from layered
fabric systems with electrospun nanofibrous web. 相似文献
106.
杂草在土壤重金属污染修复中的应用 总被引:4,自引:0,他引:4
就杂草对重金属的超富积特性、杂草在修复重金属污染土壤上的优势进行了综述,认为杂草具有抗逆境能力强、生长迅速、繁殖能力强,在环境条件适宜情况下生物量能够急剧提高等特点,可以弥补现有植物修复的缺点和不足,是较理想的土壤重金属污染植物修复资源。 相似文献
107.
城市的滨水区作为重要的景观要素和门户,其对城市环境和活力都起到不可取代的重要作用,但是由于总规的粗略规划缺少详细的指导作用,而控规往往分片区规划从而导致对滨水区缺少总体的控制,所以就需要单独对滨水片区进行研究和规划。本文通过黔江老城区滨水区实际调研找出问题,结合理论分析问题,最后解决问题,从空间打造、活力塑造、交通体系设计、绿化景观设计、人文特色表现、建筑风貌设计这几个方面探索出一些适合的滨水区规划设计对策。 相似文献
108.
The CO_2 released from respiring cells in woody tissues of trees can contribute to one of three fluxes:efflux to the atmosphere(E_A),internal xylem sap transport flux(F_T),and storage flux(DS).Adding those fluxes together provides an estimate of actual stem respiration(R_S).We know that the relative proportion of CO_2 in those fluxes varies greatly among tree species,but we do not yet have a clear understanding of the causes for this variation.One possible explanation is that species differ in stem radial CO_2 conductance(g_c).A high g_c would favor the E_A pathway and a low g_cwould favor the F_Tpathway.However,g_chas only been measured once in situ and only in a single tree species.We measured g_cusing two methods in stems of Fraxinus mandshurica Rupr.(ash)and Betula platyphylla Suk.(birch)trees in situ,along with R_S,E_A,F_T and DS.Stem radial CO_2 conductance was substantially greater in ash trees than in birch trees.Corresponding to that finding,in ash trees over 24 h,E_Aconstituted the entire flux of respired CO_2 ,and F_Twas negative,indicating that additional CO_2 ,probably transported from the root system via the xylem,was also diffusing into the atmosphere.In ash trees,F_T was negative over the entire 24 h,and this study represents the first time that has been reported.The addition of xylem-transported CO_2 to E_A caused E_Ato be 9% higher than the actual R_Sover the diel measurement period.Birch trees,which had lower g_c,also had a more commonly seen pattern,with E_A accounting for about 80% of the CO_2 released from local cell respiration and F_T accounting for the remainder.The inorganic carbon concentration in xylem sap was also lower in ash trees than in birch trees:2.7 versus 5.3 mmol L-1,respectively.Our results indicate that stem CO_2 conductance could be a very useful measurement to help explain differences among species in the proportion of respired CO_2 that remains in the xylem or diffuses into the atmosphere. 相似文献
109.
LAI Ping-z 《中国草食动物》2004,(6)
na;2. China Highway Engineering Consultant and Supervision General Company, Beijing 100101, China)In order to provide scientific basis for layout planning of logistics garden in the Pearl River Delta of Guangdong province and seek for the best layout plan,conditions for developing logistics gardens in developed countries are elaborated and conditions for developing logistics gardens in the Pearl 相似文献
110.
土壤氮素运移转化机理研究现状与展望 总被引:1,自引:0,他引:1
河南省新乡市建设路173号 水利部中国农科院农田灌溉研究所 相似文献