新疆鸟类新纪录——白腹鹞(Circus spilonotus)     

王音明  刘枫  马鸣  张国强  苟军  文翠华 《干旱区地理》2015,38(5):1085-1086

白腹鹞(Circus spilonotus)又叫东方泽鵟,在阿勒泰地区布尔津县(47°46'N, 86°49'E)有多次记录,现确定为新疆新纪录种(或亚种)。但是,在2015年5~7月繁殖期观察,发现它可能与雌性白头鹞(Circus aeruginosus)杂交。两者无论是在形态与行为,还是在地理分布隔离方面,都存在疑团,其分类地位值得商榷。  相似文献   

生猪养殖产业集聚演化的环境效应研究——以嘉兴市辖区为例   总被引：1，自引：0，他引：1  

姚文捷 《地理科学》2015,35(9):1140-1147

通过引入区位熵的方法,构建生猪养殖产业集聚演化的环境效应模型,旨在从理论层面揭示出生猪养殖污染本身的特殊性和内在的规律性。以嘉兴市辖区为样本的研究表明,生猪养殖污染集聚程度与生猪养殖产业集聚程度存在的倒U型曲线关系,本质上是生产的环境负外部性效应,以及对其实施纠正措施的演化轨迹。生猪养殖生产的环境负外部性效应曲线在污染治理政策的作用下,随着产业集聚程度的提高由向右上方倾斜而逐渐向下弯曲;在受到耕地资源约束时,会向上平移;在因下弯而减轻的污染集聚程度被因上移而增加的污染集聚程度所抵消并盖过时,污染治理政策则有可能是失效的。因此,生猪养殖污染治理政策的实施,必须将城镇化推进所引起的耕地资源的变化考虑在内。  相似文献   

微生物调剖机理及应用   总被引：6，自引：0，他引：6  

罗强  蒲万芬  罗敏  赵金洲 《地质科技情报》2005,24(2):101-104

岩芯试验和矿场应用发现,微生物可以在多孔介质中生长、运移和繁殖,代谢产生生物聚合物,并进一步形成生物膜.生物聚合物在地层中可以通过条件的改变而形成凝胶;生物膜由于其致密性也可以对高渗透层产生选择性的封堵,调整吸水剖面,提高原油采收率.对生物矿化作用的进一步研究有助于微生物调剖机理的完善和应用.微生物调剖技术以其设备简单、施工简便、经济环保而在提高油田采收率方面得到广泛的应用.  相似文献   

煤层气成藏的宏观动力能条件及其地质演化过程--以山西沁水盆地为例   总被引：10，自引：0，他引：10  

吴财芳  秦勇  傅雪海  曾勇 《地学前缘》2005,12(3):299-308

煤层气成藏维系于其能量平衡系统,宏观上受控于“四场互动”过程,核心是能量的有效传递及其地质选择过程。以沁水盆地为例,对构造动力能、热动力能、地下水动力能等宏观动力能的地质演化过程进行了深入探讨,阐明了不同宏观动力能对煤层气成藏的控制作用。结果表明:研究区构造动力能及其演化总体经历了4个阶段;热动力能及其演化和由其控制的煤化作用同样经历了4个阶段;地下水动力能及其演化包括3个阶段。其中,燕山中期的剧烈岩浆活动是宏观动力能条件演化的关键时期。以构造动力能为主线,将其他能量场贯穿起来,可知宏观动力能与煤层气成藏之间的耦合关系如下:盆地北部阳泉—寿阳区域,是煤层气成藏有利区域之一,但不利于煤层气高产;盆地南部晋城—阳城及沁水北部区域,不仅是煤层气成藏有利区域,而且利于煤层气高产;盆地中部沁源地区是煤层气成藏和高产的有利区域;盆地东部的屯留—襄垣区域是煤层气成藏有利区域之一,但不利于煤层气高产。  相似文献   

海洋中型浮游动物的选择性摄食对浮游植物群落的控制   总被引：5，自引：0，他引：5  

王小冬  孙军  LIU Dong-yan  刘东艳  汪岷 《海洋科学进展》2005,23(4):524-535

海洋中型浮游动物的选择性摄食很大程度上影响着浮游植物种群的变化,控制着海洋初级生产力的节律、规模和归宿。从海洋中型浮游动物选择性摄食对有害藻华的控制、中型浮游动物的选择性摄食机制、中型浮游动物选择性摄食的研究方法和中型浮游动物的选择性摄食模型四个方面探讨了中型浮游动物选择性摄食对控制浮游植物种群演替的贡献,为进一步预测和控制有害藻华发生提供科学依据。  相似文献   

Reproductive cues in Panulirus ornatus     

N.G. Sachlikidis  C. M. Jones  J. E. Seymour 《新西兰海洋与淡水研究杂志》2013,47(2):305-310

Two experiments were performed to assess the effect of photoperiod and temperature on spawning of Panulirus ornatus. In experiment 1, sexually mature lobsters taken from the wild during summer were held at one of two photoperiods, winter (13 Light: 11 Dark) and summer (14.5 Light:9.5 Dark). Additionally, lobsters were also exposed to either summer (29°C) or winter (24°C) average water temperatures. Spawning was significantly greater when animals were exposed to summer photoperiod than to winter photoperiod, irrespective of temperature. Although a higher percentage of lobsters spawned when placed under a higher temperature, this trend was not statistically significant. In experiment 2, sexually mature lobsters were taken from the wild during winter and exposed to the same two photoperiods as in experiment 1, at a summer equivalent temperature of 29°C. Breeding started earlier and was more successful at the summer photoperiod. Time to first breeding was 17 weeks after exposure to summer photoperiod, compared with less than 1 week in experiment 1, and did not occur until individuals had moulted. Moulting occurred in 81% of lobsters, primarily after an increase in temperature to 29°C. The time between moulting and mating was varied and there was no significant difference in moult frequency between the two experimental photoperiods. After the lobsters had moulted, breeding success was reached earlier if photoperiod was lengthened. Results suggest photoperiod is the primary cue for the onset of gonad maturity and mating activity, with temperature playing a less important role. Physiological rest and possibly a moult may be required between breeding seasons before spawning can occur. Furthermore, temperature may be an important cue for pre‐reproduction moulting.  相似文献   

Evaluation of the "time factor" and "light factor" methods for estimating daily phytoplankton production at the sea surface     

《African Journal of Marine Science》2013,35(1):139-143

Daily phytoplankton production was estimated at the sea surface in the southern Benguela Current during January, March, April and October 1978 by different methods of calculation. Actual daily production (P_{24 meas}) was obtained from a series of short-term (3—4 h) incubations spanning 24 hours. Daily production was also extrapolated from single measurements during daylight by the "time factor" and "light factor" methods of calculation. These estimates (P_{24 calc}) vary considerably from P_{24 meas}, but on average they underestimate daily production. Estimates by the "light factor" method are generally lower and more variable than those from the "time factor" method. Differences in amplitude and timing of fluctuations in the rate of net production during daylight make it impossible to calculate reliable factors for correcting diel variations in photosynthesis when estimating daily production from short-term measurements. It is suggested that the effects of diel variation in production are likely to be less significant in the euphotic zone as a whole than at the sea surface alone.  相似文献   

三角帆蚌(Hyriopsis cumingii)外套膜无核珍珠颜色成因的育珠实验     

张根芳  许式见  方爱萍 《海洋与湖沼》2013,44(2):532-536

用紫色蚌和非紫色蚌制取细胞小片,分别插入紫色蚌和非紫色蚌外套膜内,探究三角帆蚌(Hyriopsis cumingii)无核珍珠颜色与制片蚌、育珠蚌的关系;用不同类型制片蚌的不同部位制取细胞小片,分别插入育珠蚌外套膜内,进一步探究珍珠颜色与制片蚌珍珠质颜色的关系。结果表明,以紫色蚌为制片蚌,所产的珍珠为紫色系,珍珠紫色深浅与细胞小片所对应部位的制片蚌珍珠质紫色深浅呈正相关。以非紫色蚌为制片蚌,所产的珍珠有白色系和黄色系,珍珠黄色深浅与细胞小片所对应部位的制片蚌珍珠质黄色深浅呈正相关。三角帆蚌外套膜无核珍珠颜色是由提供细胞小片的制片蚌珍珠质颜色所决定,而与育珠蚌无关。该结论支持珍珠囊表皮细胞来自于移植细胞小片的观点。该结果表明,通过定向选育纯紫、纯白色贝壳珍珠质三角帆蚌新品系,即可培育出纯紫、纯白色无核珍珠。  相似文献   

选择性滤波同位网格有限差分法在地震波数值模拟中的应用.          下载免费PDF全文

丘磊  田钢  王帮兵 《地震学报》2012,34(4):463-475

引入计算空气声学领域的选择性滤波同位网格有限差分算法（SFFD法）用于二维地震波数值模拟．SFFD法使用经过优化的11点DRP同位网格差分格式,对空间一阶导数进行离散近似,同时采用选择性滤波方法来消除同位网格差分所产生的格点高频振荡,它既提高了数值模拟的精度, 又保证了求解过程的稳定性．数值实验结果表明,SFFD法能够达到O(Delta;x8, Delta;t4)阶交错网格算法同样的精度,同时该方法还具有很强的适应性,能够应用于存在着强泊松比差异的介质模型中,完整地模拟地震波传播过程中各类型的波场,并且对复杂非均匀介质的适应能力也很好．此外,由于避免了交错网格算法在曲线坐标系和一般各向异性介质的数值模拟时所需进行的复杂的插值运算, SFFD法在这些问题上也有着很好的应用前景．   相似文献   

大泷六线鱼人工繁殖及育苗技术初步研究   总被引：2，自引：0，他引：2  

潘雷  胡发文  高凤祥  菅玉霞  张少春  王雪  郭文 《海洋科学》2012,36(12):39-44

总结了2009 ～2010年关于大泷六线鱼(Hexagrammos otakii)人工繁殖及育苗技术的研究结果,论述了大泷六线鱼苗种繁育的关键技术.通过对亲鱼强化培育和促熟,创新发明人工平面授精技术和网箱吊式孵化技术,加强饵料的合理搭配与投喂、水质调控技术等措施,突破了大泷六线鱼人工繁殖的技术难点,明显提高了受精率、孵化率和苗种成活率,解决了人工繁殖大泷六线鱼苗种生产问题.在水温16～ 17℃,盐度31,光照500 ～ 1000 1x的培育条件下,大泷六线鱼鱼苗经过90 ～ 100 d的培育,全长生长至5 ～6cm.2009和2010年分别培育出全长5 cm以上大泷六线鱼鱼苗4.1万尾、11.4万尾,苗种成活率分别达到41.7％、43.2％,在国内首次实现了大泷六线鱼人工规模化繁育.  相似文献