共查询到18条相似文献,搜索用时 62 毫秒
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发头裸腹溞休眠卵发育的温度因子分析 总被引:2,自引:0,他引:2
测定了不同温度下发头裸腹溞(Moina irrasa)体眠卵的孵化时间及孵化率;取最先孵出和过半数孵出的两组数据依莱奥姆积温法则求得种群休眠卵最低临界温度为12.00℃,最低有效积温为441.61℃·h;最低亚致死高温点(即最适温度)为35.16℃,以及最低死亡高温点39.44℃。种群中过半数的临界温度为12.88℃,过半数有效积温为557.10℃·h,过半数的亚致死高温点为35.56℃以及过半数死亡高温点为39.49℃。讨论了这些参数在枝角类集约化培养中休眠卵的有效保存与启用所具有的实践意义。 相似文献
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发头裸腹溞休眠卵发育的温度因子分析 总被引:2,自引:0,他引:2
测定了不同温度下发头裸腹溞(Moina irrasa)体眠卵的孵化时间及孵化率;取最先孵出和过半数孵出的两组数据依莱奥姆积温法则求得种群休眠卵最低临界温度为12.00℃,最低有效积温为441.61℃·h;最低亚致死高温点(即最适温度)为35.16℃,以及最低死亡高温点39.44℃。种群中过半数的临界温度为12.88℃,过半数有效积温为557.10℃·h,过半数的亚致死高温点为35.56℃以及过半数死亡高温点为39.49℃。讨论了这些参数在枝角类集约化培养中休眠卵的有效保存与启用所具有的实践意义。 相似文献
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为了检验已记录的3种裸腹溞(发头裸腹溞(Moina irrasa)、短型裸腹溞(Moina brachiata)、微型裸腹溞(Moina micrura))的系统分类,用试剂盒法分别提取3种裸腹溞的基因组DNA.利用特异性引物,通过PCR扩增了3种裸腹溞的16S r DNA部分序列,并与来自Gen Bank中每个种类相似度较高的裸腹溞属序列进行分析.结果表明,3种裸腹溞的平均种间相似度为88.7%,碱基中A+T含量均明显高于G+C含量.本研究的发头裸腹溞的16S r DNA序列与Gen Bank所下载的多刺裸腹溞(Moina macrocopa)的16S r DNA序列相似度为99%,遗传距离(K2P双参考模型)为0.5%,属种内范围;两个地区的短型裸腹溞测得的16S r DNA序列与Gen Bank下载的欧洲短型裸腹溞的16S r DNA序列序列相似度相对较低(88%~90%),遗传距离较大(13.2%~13.5%左右),已达到属内种间分化水平.基于16S r DNA构建的NJ树和贝叶斯树也支持以上结论.结果表明,本研究的发头裸腹溞可能为多刺裸腹溞,本研究用的短型裸腹溞与Gen Bank下载的欧洲短型裸腹溞已经达到种间分化的标准.由于缺乏物种形态资料和其他分子标记的对比,3种裸腹溞的分类地位还需进行更深入的探讨. 相似文献
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不同培养条件下多刺裸腹溞的生殖和种群增长参数 总被引:2,自引:0,他引:2
于 1996年在实验室对多刺探腹溞(Mbina macrocopa)种群的增长率及相关生态学参数进行了研究.结果表明,3个温度梯度(24、28和32℃)和3个面包酵母(Saccharomyces cerevisi-ae)密度(0.25、2 5和25 x 10_6cell.mL~(-1)下,以28℃时内禀增长力(r_m)最高;28℃时,面包酵母的投喂密度为25×10_6cell.mL_(-1)时,其r_m最大.温度28℃,面包酵母密度为25×10_6cell.mL~(-1)时,该溞的繁殖前期最短,繁殖期和寿命均最长,并且怀卵量(每窝产仔数)最大.该溞的种群密度和瞬时增长率分别在接种后第7d和第3-4d达高峰.该搔批量培养时采收时间以第5d为宜. 相似文献
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温度对两品系蒙古裸腹溞(Moina mongolica Daday)种群增长和生殖的影响 总被引:4,自引:0,他引:4
本文报道两品系蒙古裸腹溞(Moina mongolica Daday)(晋南、内蒙)在5种温度梯度下(15℃、18℃、25℃、28℃、32℃)的种群内禀增长率(rm)、总生殖量、寿命、产幼间隔期、生殖频率和产幼前发育期,以及在28℃条件下两品系生物学的研究结果.结果表明,温度对两品系蒙古裸腹涵的种群繁殖均具有显著的影响.在试验温度范围内,随着温度升高,两品系蒙古裸腹涵的产幼前发育期、产幼间隔期、寿命随之缩短;而内禀增长率、总生殖量、生殖频率随温度升高而先升后降.温度28℃是两品系蒙古裸腹涵种群增长的最适温度,28-32℃是其种群增长的最适温度范围.晋南品系10组个体重复试验的内禀增长率结果仍高于内蒙品系.经比较可知:在相同温度条件下,晋南品系在种群增长能力方面要明显强于内蒙品系,反映在前者的内禀增长率要大于后者.在相对较高或较低的温度条件下,内蒙品系则表现出更强的耐受能力. 相似文献
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中华窄腹剑水蚤是中国河流中发现的土著种类,具有较强的生态入侵能力,通过从西江抽水进入大镜山水库,成为该水库的优势浮游甲壳类,通过2005-2006两年的采样监测,初步分析了该水库中中华窄腹剑水蚤的种群特征及其对浮游甲壳类的群落动态和结构的影响.两年共检出浮游甲壳类13种,其中,桡足类4科7属9种,枝角类3科4属4种,中华窄腹剑水蚤是水库的优势种,两年浮游甲壳类丰度的范围是3.82-364.85ind/L,峰值出现在春季,两年变化趋势相似,水库浮游甲壳类的体长分布范围为0.07-1.25mm,主要由小个体的类群(体长在0.07-0.4mm之间)组成,个体较大(大于0.5mm)的枝角类和桡足类数量很低,中华窄腹剑水蚤和其无节幼体的丰度占甲壳类总丰度的50%以上,其丰度的动态分布与浮游甲壳类的总体丰度的动态分布一致,中华窄腹剑水蚤主要以三种形式(无节幼体Ⅰ期,桡足幼体后期和成体)存在于水体中,存活曲线呈Ⅲ型,无节幼体的丰度远高于后两者之和,该种类能成为水库优势种主要是由水库成度变化剧烈水环境特征和其自身的生态学特点决定的,中华窄腹剑水蚤丰度与叶绿素a浓度具有显著正相关性,与抽水入库量具有极显著的负相关性,作为一个生态入侵种类,中华窄腹剑水蚤降低水体中浮游甲壳类生物多样性,并替代了原来的土著优势种. 相似文献
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有毒铜绿微囊藻对鱼和溞的毒性 总被引:12,自引:2,他引:12
用有毒铜绿微囊藻细胞及其从毒细胞中提取的毒素喂养和腹腔注射鱼类,结果表明:(1)微囊藻毒素MCYST-LR对所有实验过的鱼有毒害作用(LD_(50)为110-500μg/kg).注射毒素24h后,鱼肝电镜超微结构观察均表现出肝损伤.(2)在受控条件下,当用有毒铜绿微囊藻作为食物喂养日鲢和罗非鱼时,鱼类能在以毒藻为唯一食物的环境中生活20d以上.白鲢和罗非鱼粪便的毒性比喂食藻类的毒性分别降低约2—4.5倍,其肝的超微结构现察仍有轻度损伤.(3)在培养液中加入15μg/mLMCYST-LR和用实验室纯培养的铜绿微囊藻作为食物培养枝角类时,均可使它们在48h死亡.以无毒微囊藻培养时则生长不良亦不怀卵,表明它不是枝角类合适的食物. 相似文献
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AN EXPERIMENTAL STUDY ON THE PROCESS OF INTERGRANULAR PRESSURE SOLUTION OF PLAGIOCLASE GOUGE UNDER HIGH TEMPERATURE AND PRESSURE: METHOD AND PRELIMINARY RESULTS 下载免费PDF全文
To understand the mechanism of lower-crust earthquake and slow slips, it is necessary to study the frictional properties of mafic rocks and their major rock-forming minerals. Previous studies have performed a series of experimental researches on gabbro, basalt and their major constituents.
According to the results of previous experiments, frictional sliding of plagioclase under hydrothermal conditions(100~600℃)shows a property of velocity weakening, and the experimental results show that both the direct rate effect parameter(a)and the healing effect parameter(b)increase with temperature, a typical feature for thermally-activated processes. Velocity weakening means property of a shear band that has a stronger friction healing effect than the direct rate effect in the rate and state friction constitutive framework, and the healing effect(b value)in constitutive relation mainly reflects the increase in contact area with time under hydrothermal conditions, with some minor effect of structural changes. Since the microphysical mechanism of feldspar minerals at the contacts is mainly brittle cataclasis for temperatures below 600℃, the significant frictional healing effect in this case can only be explained by the mechanism of pressure solution. In order to determine if the dissolution process of plagioclase actually occurs on the laboratory time scale, we conducted hydrostatic experiments on plagioclase powder samples under hydrothermal conditions whereby frequent contact switch between particles seen in frictional sliding experiments can be avoided, making the observation on the dissolution sites possible.
Experimental temperatures were 400℃ and 500℃, with confining pressure of 90~150MPa, pore pressure of 30MPa, with 2mm initial thickness of fault gouge. The mechanical data show that a creep process occurred in the plagioclase fault gouge in the experimental temperature and pressure range; and the microstructures of the experiment show that precipitation of new grains is prevalent as the product of pressure solution process between plagioclase particles. At the same time, it is observed that the contact points have an appearance similar to fused, fuzzy structure as signatures of dissolution. The results of our experiments provide a definite experimental evidence for the healing mechanism in friction of plagioclase and for the theoretical relation between unstable slip and the pressure solution process.
The results of the experiments are summarized as follows:
(1)Drainage rate of pore water in plagioclase gouge was high in the first few hours of experiment, but gradually decreases over time for both temperature and pressure series of experiments slowing down to a steady state. This feature indicates that there is a creep process that evolves inside the plagioclase gouge.
In the temperature-series experiments, the drainage rate of the pore water in the plagioclase gouge at 400℃ is relatively low than the cases for higher temperatures. Thus, the applied temperature is positively correlated with the creep of plagioclase gouge.
(2)Scanning electron microscopy(SEM)observations of the experimentally deformed samples were performed on thin sections cut along the sample axis. Firstly, from the images of microstructure, it was found that the degree of particle fracture became more significant at a higher effective pressure, with smaller pore volume between particles. In the temperature-series experiments it was found that the degree of compaction of plagioclase gouge increased with increasing temperature. Precipitation of plagioclase grains in layered structures was generally observed in high-magnification images, indicating the presence of pressure solution processes. Contact points were also found to be in a state of ambiguity that seems to be a fused morphology, but the details of the structure remain to be determined by further observations.
The above results indicate that the pressure solution process of plagioclase particles can occur on a typical laboratory time scale, and the results of this study provide robust experimental evidences for the theory that links between pressure solution and the mechanism of frictional healing and unstable slips for plagioclase. 相似文献
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EXPERIMENTAL STUDY ON THE EFFECT OF WATER ON THE STRENGTH AND DEFORMATION MECHANISM OF CARRARA MARBLE AT HIGH TEMPERATURE 下载免费PDF全文
We performed deformation experiments using Carrara marble in dry and wet conditions under temperature of 400~700℃ and confining pressure 300MPa with two different strain rates. Water contents of deformed samples were measured using FTIR spectroscopy. The microstructure and deformation mechanisms of samples were observed under optical microscopy, scanning electron microscopy and energy spectroscopy analysis. The mechanical data show that samples display strain hardening at 400℃, and transition to steady creep at temperature from 500~700℃. The strength of marble reduced gradually with elevated temperatures or decreased strain rate. However, water effect to the strength of the marble is significantly weak. Microstructures observed show that the deformation is cataclastic flow in dry samples, fracture and pressure solution in wet samples at 400℃. Samples underwent brittle-plastic transition at 500℃. Dislocation glide is major deformation mechanism for dry samples at 600℃. Dislocation climb and dynamic recrystallization are major deformation mechanism for wet samples at 600℃ and for all wet samples and dry samples at 700℃. Lower strain rate and higher water content could promote the process of pressure solution and diffusion as well as dynamic recrystallization. 相似文献
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用时域分析组合模型建立了100万年来60°N6月份太阳辐射量时间序列、宝鸡黄土粒度时间序列、渭南夏季风指数时间序列的动态模型.研究结果表明,时域分析组合模型较好地提取了时间序列的信息,得到的几个显著周期T=133,100,89,41,23,19ka,与地球轨道三要素的变化周期接近.用组合模型拟合实测数据,精度是高的;用其预测未来气候替代性指标时间序列的变化情况,发现未来气候有向干冷方向发展的趋势.时域分析组合模型为研究气候变化趋势提供了一种定量分析、预测的方法. 相似文献
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根据哈萨克斯坦萨特地震台、中国新疆乌什地震台的地震资料分别作出单台小地震平均机制解,研究了1990年11月12日阿拉木图附近的巴依沙隆6.7级地震前后小区域应力场的变化.同时利用乌鲁木齐地震台的资料研究了该区在强震前后小地震平均机制解的变化.研究表明:天山地区强震前单台小地震平均机制解有P轴转向、初动符号矛盾比下降等征兆反应。对将单台小地震平均机制解用于地震预报等问题进行了讨论. 相似文献
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地震非均匀度的研究及在强震中期预报中的应用 总被引:27,自引:14,他引:27
室内岩石破裂实验表明,主破裂前声发射事件在时间分布上随着应力增强存在着均匀-非均匀现象。本文据此提出了一个能够有效刻画强震前中小地震活动在时空分布上不均匀性的参量-地震非均匀度(GL值)。据对中国大陆1920年以来43次Ms>7.0大震震前5年G时间变化扫描结果,发现除少数边界附近的大震外,所有7级大震震前1-3年,在震中一定范围内5级以上地震活动显示出明显的非均匀状态(GL值大于1.0);同时, 相似文献