首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
The electric organ of Torpedo, besides providing abundant amounts of cholinoceptive post-synaptic membrane for the isolation of the acetylcholine receptor protein, is a rich source of cholinergic nerve terminals. Using perfused, innervated tissue blocks from which synaptic vesicles in different functional states can be isolated, much information can be obtained about synaptic-vesicle dynamics. So far this is consistent with the view that the synaptic vesicles are the source of transmitter released on stimulation and that uptake of newly synthesized transmitter by the vesicles is dependent on their having discharged their previous charge of transmitter in at least one cycle of exo- and endocytosis. Studies of the protein composition of the vesicle membrane, especially when combined with similar information about the external presynaptic membrane, purified samples of which are now available from synaptosome (T-sac) preparations, promise to throw new light on the molecular mechanism underlying vesicle exo-/endocytosis.  相似文献   

2.
三丁基锡在鱼脑中的吸收与沿轴突传递的研究   总被引:1,自引:0,他引:1  
为证实水中三丁基锡是否与Hg2+,Cd2+与Mn2+等离子相类似,即由鱼的感觉器官进入神经系统,再经过轴突传递进入大脑。笔者将一组虹鳟鱼暴露在含有113Sn-TBT(4 2kBq L)的水中;另一组经静脉注射113Sn-TBT。用全身放射自显影方式给出113Sn-TBT在鱼体中的分布。结果表明,113Sn-TBT可以通过鱼感觉器官,例如隆起颗粒进入鱼脑,并大量累积。静脉给药组的鱼大脑中也出现了放射性标记,表明TBT能通过血脑屏障到达大脑。由此得出结论:TBT可由水→鳃→血流→血脑屏障→大脑的传递过程在鱼的大脑中累积,但TBT也能经过水暴露敏感神经的端点被鱼体吸收,再由轴突传递直接输送到大脑。   相似文献   

3.
 Chemical synapses are highly specialized cell–cell junctions designed for efficient signaling between nerve cells. Distinct cytoskeletal matrices are assembled at either side of the synaptic junction. The presynaptic cytomatrix at the active zone (CAZ) defines and organizes the site of neurotransmitter release from presynaptic nerve terminals. The postsynaptic density (PSD) tethers neurotransmitter receptors and the postsynaptic signal transduction machinery. Recent progress in the identification and characterization of novel CAZ and PSD components has revealed new insights into the molecular organization and assembly mechanisms of the synaptic neurotransmission apparatus. On the presynaptic side, Bassoon and Piccolo, two related giant proteins, are crucially involved in scaffolding the CAZ. On the postsynaptic side, two families of multi-domain adaptor proteins, the MAGuKs (membrane-associated guanylate kinase homologs) and the ProSAP (proline-rich synapse-associated protein, also termed Shank) family members are thought to be major organizing molecules of the PSD.  相似文献   

4.
At present, the notion is generally accepted that societies have to combat climate change. The reduction of CO2-emissions, an important cause for global warming, has become a priority, and consequently there is increasing pressure on governments and industries to come forward with initiatives to reduce CO2-emissions. This is highly relevant for the transport sector, as the share of transportation is still increasing, while other sectors are reducing their CO2-footprint. The main purpose of this paper is to present a methodology to analyse the CO2-emissions from container terminals, illustrated by the Port of Rotterdam.The objective of this paper is twofold. Firstly, the development of a methodology to analyse and gain a better understanding of the CO2-emissions by container terminals in port areas is described. Secondly, the most effective solutions to reduce CO2-emissions by container terminals in port areas are identified. The study provides insight into the processes of container transshipment at the terminals and the contribution of these processes to the CO2-emissions of the container terminals. Using these insights, potential solutions to reduce the CO2 at the terminals are identified and policy proposals are made for the operators of existing terminals and for governments.The most effective measure for CO2 reduction is undoubtedly the adaptation of the terminal layout as in the example of the Rotterdam Shortsea Terminal. This makes it possible to reduce the CO2-emissions of the current terminals by nearly 70 per cent. The other perspective is the incorporation of mixing 30 per cent biofuels with the presently used diesel. This results in a reduction of CO2-emissions by between 13 and 26 per cent per terminal and a reduction of the emissions of the total container sector by 21 per cent. On the basis of these findings, concrete recommendations are made to reducing CO2-emissions at container terminals.  相似文献   

5.
汽油储油库是城市挥发性有机物(VOCs)的重要来源之一,为减少VOCs排放,北京市于2006年开始推动储油库安装油气回收装置,每年监测储油库VOCs排放情况.分析了2012~2019年北京市储油库VOCs排放变化特征,发现2012~2019年北京市储油库VOCs进口浓度经历下降-上升-下降历程,2019年进口平均浓度为165.3 g·m-3;出口浓度趋于下降趋势,2019年出口平均浓度为7.3 g·m-3;北京市储油库VOCs去除效率总体趋于稳定,为45.5%~100%.但在油气回收装置出口排放浓度达标率大幅提高的同时,出现了储油库回收装置去除效率反而下降现象.因此,提出加强过程管理,增加检查油气回收装置的运行年限和检查维护保养记录,并将去除效率指标纳入管控范畴,执行"双指标"达标要求等建议.为未来制定储油库精细化管理措施,进一步改善大气环境质量提供科学依据.  相似文献   

6.
吴维平 《交通环保》2001,22(1):9-14
在对大气环境质量计算机模拟方法和基本模式讨论的基础上,分析了常用的三个基本计算机模式FDM、AFTOX、ISC3VIEW的使用范围与边界条件等,对中国港口大气环境质量计算机预测模拟应用和应注意的一些问题进行了研究和探讨。  相似文献   

7.
主要讨论了利用LonWorks现场总线技术来实现城市污水处理厂污水处理系统的实时控制,本系统采用IPC和PLC控制结构对现场的各种设备进行实时控制和数据的采集,通过LonWorks现场总线网络自动收集和传输污水处理系统的数据到中心控制室,中心控制室的计算机分析数据后对现场进行实时监控,实现污水处理的自动控制和无人化管理,中心控制室也可以通过Internet与远程终端互相通讯,向各终端提供实时的数据和远程终端对污水处理系统的实时监控。  相似文献   

8.
Research in molecular neurobiology has recently entered a new phase of rapid development as a result of the application of the techniques of molecular genetics. This is illustrated by recent work on the electric ray (Torpedo marmorata and T. californica), whose electric organ is a rich source of cholinergic synapses. Other examples from recent literature of the application of the recombinant DNA technique to the mammalian central nervous system are given and possible future developments are discussed.  相似文献   

9.
介绍了液体危化品的特点,对装卸船作业过程中静电产生的途径及主要危害进行了分析,并提出了相应的防范对策.  相似文献   

10.
城市地表灰尘中的重金属已成为城市环境和人类健康最重要的威胁之一. 为评价地表灰尘重金属的污染水平,研究了福州市公交枢纽站地表灰尘中的重金属质量分数、来源及其可能产生的健康风险. 结果表明:福州市公交枢纽站地表灰尘中w(Cr)、w(Cu)、w(Zn)和w(Cd)分别是福州市城区土壤的2.74、4.21、4.01和4.68倍. 灰尘中重金属Co、Ni和Mn主要来源于城市土壤,Cd、Pb和Cu来源于交通运输过程,Cr来源于城市土壤和交通运输,Zn主要来源于交通运输、城市生活污染和工业活动等复合污染源. 不同暴露途径的重金属暴露剂量和非致癌风险大小排序为消化道>皮肤接触>呼吸吸入. 地表灰尘中重金属非致癌总风险为儿童高于成人. 致癌重金属的暴露风险为Cd>Ni>Cr. 城市公交枢纽站地表灰尘中重金属污染受交通运输影响较大.   相似文献   

11.
为更科学合理地对低温LPG港口、码头进行安全风险分析,对工程实例采用定量风险评估(QRA)、事故后果模拟方法,研究了低温LPG码头的风险,给出了低温LPG码头个人风险曲线。对比了低温LPG码头和常温LPG码头的事故后果影响范围。结果显示,码头低温LPG泄漏后的危害距离是常温LPG泄漏后危害距离的2.7倍以上,低温LPG码头的安全风险高于常温LPG码头的安全风险;低温LPG码头泄漏事故可能影响到邻近码头的安全。提出了降低风险的关键安全对策措施,可有效降低风险约1个数量级。定量风险分析工作是JTS 158—2019《油气化工码头设计防火规范》等标准规范的有益补充,可为LPG码头选址、总平面布置、工艺安全、泄漏事故应急预案提供参考。  相似文献   

12.
我国挥发性有机液体储库VOCs排放标准现状分析   总被引:2,自引:0,他引:2       下载免费PDF全文
针对地方政府、VOL(挥发性有机液体)储库和治理企业进行VOCs(挥发性有机物)治理时面临排放标准选择困惑的现状,根据地方行业性标准>国家行业性标准>地方综合标准>国家综合标准的标准选择顺序,对我国部分地区(北京市、上海市、厦门市、重庆市)现行的相关排放标准进行分析.结果表明:①对于汽油储库,全国均执行GB 20950—2007《储油库大气污染物排放标准》(北京市除外);②对于原油及成品油(汽油除外)储库,各地区优先执行本地区《工业企业挥发性有机物排放控制标准》,其次是本地区《大气污染物综合排放标准》,最后是国家的GB 16297—1996《大气污染物综合排放标准》,北京市、上海市、厦门市和重庆市《大气污染物综合排放标准》中NMHC(非甲烷总烃)最高允许排放质量浓度分别是GB 16297—1996标准限值的42%、58%、83%和100%;③工业企业VOCs排放标准或大气污染物综合排放标准的NHMC最高允许排放质量浓度约为GB 20950—2007标准限值的3‰,因此准确选择排放标准显得尤为重要.研究显示,生态环境部应尽快修订GB 20950—2007,将适用范围扩大为原油及成品油或VOL储库,并适度加严标准限值,推动行业有序发展.   相似文献   

13.
李又明 《交通环保》2001,22(4):36-39
在回顾现有国际规章对散装液体危险货物作业码头及装卸操作要求的基础上,分析了中国相关码头及作业现状,提出了在安全和防污染等方面需要研究解决的问题。  相似文献   

14.
为识别港口机械作业特征及污染物排放情况,在对珠三角港口实地调研基础上,提出了基于单位作业量油耗的分作业方式、分机械类型的精细化港口机械排放清单估算方法,并对该方法油耗估算值与港口油耗统计值、其他估算方法油耗值之间的差异进行对比分析,以验证其可靠性与适用性,最后利用该方法建立了珠三角2014年港口机械排放清单.结果表明:对于珠三角本地港口,该方法油耗估算值与统计值无明显差异(相对误差为-5.9%~6.8%);对于其他研究区域港口,油耗估算值、统计值与其他估算方法估算值的差异均在合理范围(-35.8%~53.8%和-17.5%~2.6%)内,表明该方法具有较好的可靠性与适用性.清单结果显示,2014年珠三角港口机械排放的SO2、NOx、CO、PM10、PM2.5和HC分别为633.6、4610.6、3391.2、226.9、216.0和728.8 t.其中,集装箱码头是最主要的港口机械使用场所,集装箱专用机械和水平运输机械是主要贡献机械类型.通过清单的横向对比和不确定性分析,表明该研究所建立的清单具有一定的合理性.该研究建立的清单估算方法在较大程度上弥补了现阶段我国在港口机械保有量和油耗数据统计方面的不足,为完善港口城市排放源清单建立、污染减排评估及空气质量管理等方面提供了方法参考.   相似文献   

15.
福州港液货危险品码头安全,防污染管理对策   总被引:2,自引:0,他引:2  
液货危险品码头的安全与防污染管理水平高低直接关系到港口、码头、水域的安全。文中着重福州港对该类码头是如何进行管理,目前主要存在的主要问题及对策。  相似文献   

16.
In amphibians the lateral line sense organs, i.e., mechanoreceptors (neuromasts) and electroreceptors, develop autonomously from placodal tissue, with no need for innervating nerve fibers. The present study deals with the question whether or not the mechano- and the (ampullary) electroreceptors develop in the same manner in teleosts. On the tail of larval catfish, Silurus, the first mechano- and electroreceptors appear several days after hatching in two longitudinal rows, one along the outgrowing main branch of the lateral line nerve and one along its ventral branch. Prevention of outgrowth of both nerve branches by repeated nerve sectioning, before the receptors form, shows (1) that the mechanoreceptors can develop without innervation as in amphibians, and (2) that the electroreceptors do not develop without innervation, unlike amphibian electroreceptors. These results are discussed with regard to the placodal origin and the phylogeny of the two sense organs.  相似文献   

17.
The amphioxus is the only surviving prevertebrate segmented chordate. In this animal Hatschek's pit has long been regarded as a putative homologue of the adenohypophysis because of the presence of secretory granules and immunoreactive cells to vertebrate gonadotrophic hormone in this organ. We found that the nerve cord extends a protrusion to the pit along the right side of the notochord. Furthermore, secretory granules were found not only in the pit but also in the protrusion of the nerve cord. These results suggest that Hatschek's pit and the nerve protrusion are homologous to the adenohypophysis and neurohypophysis, respectively. We believe that this is an evidence for the presence of the neuroendocrine link between the central nervous system and Hatschek's pit in the amphioxus. Received: 2 November 1998 / Accepted in revised form: 11 February 1999  相似文献   

18.
港口油气污染扩散及源强计算方法的探讨   总被引:3,自引:2,他引:3  
吴维平 《交通环保》1999,20(6):11-15,38
系统分析了港口油气污染扩散的特点式,对油港油原强及扩散速率计算方法进行了研究和验证,对适用国内油港油气扩散模拟源强公式及计算方法进行了探讨。  相似文献   

19.
王有清 《交通环保》2000,21(4):8-10
论述了煤炭港口大气降尘与煤尘污染的关系。通过对秦皇岛港煤三、四期码头及附近区域大气降尘的长期连续监测以及对资料进行整理,分析了大气降尘的分布特征,从而得到港口投产以来的煤尘污染变化及趋势。  相似文献   

20.
北京市医院废物产生与利用、处置现状及对策分析   总被引:10,自引:0,他引:10  
根据 1 998年北京市部分医院 ( 1 0 6家 )的医院废物申报登记资料 ,整理统计了医院废物的组成和单位产生量 (公斤 /床·月 )以及废物的主要去向 ;分析了不同类型和规模的医院与废物组成比例、单位产生量间的关系以及废物利用、处置中存在的问题 ,并提出了相应的污染控制对策  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