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411.
EFFECTS OF TEMPERATURE AND Ca^2+ ON THE LARVAL DEVELOPMENT OF THE DECAPODA CRUSTACEAN : ERIOCHEIR SINENSIS 总被引:1,自引:0,他引:1
With increasing demand in China for the mitten crab larvae, understanding its survival mechanism gets more important. This research focused on the effects of temperature and Ca^2 on the larval growth and development. Eriocheir sinensis larvae were reared in laboratory under 21 different combinations of temperature (15, 20, 25℃) and Ca^2 content (120, 130, 140, 150, 160, 170, 180mg/l) and constant salinity (20) and pH (8), The results suggested that the survival rate increases with temperature and Ca^2 content. These combinations of temperature and Ca2 content maximized survival rate inour study and it may be the optimum water environmental conditions for culturing the larvae. To predict surviving larvae number under different water environmental conditions, 21 dynamic mathematical models were developed. This for the first time observation of the zoeal Ⅵ larvae of the Changjiang River E.sinensis population showed that they occurred under stressed water environmental conditions: temperature of 15℃ and Ca^2 content of 120,130mg/l. 相似文献
412.
赖泽兴 《广东海洋大学学报》1994,(1)
在常规催产剂中加入适量的A型添加剂,可使鳜鱼的催产率提高10%以上,受精率提高5%以上。使用15×10-6的福尔马林,可有效地杀灭寄生于鳃及体表的寄生虫和细菌,从而大大提高苗种成活率。 相似文献
413.
414.
建立区域坐标系问题的讨论 总被引:11,自引:4,他引:7
讨论了在国家坐标系下建立区域坐标系的方法和基本要求。指出移动中央子午线法或改变椭球参数法存在的弱点,而抵偿高程面的比例系数法理论正确,方法简便易行。 相似文献
415.
Ray equation migration of wide-angle reflections in 2-D medium is one kind of Kirchhoff prestack depth migration method. Based
on ray theory, this method can be used extensively in 2-D inhomogeneous medium, and shows its advantage in wide-angle reflection
study. After calculating ray fields, we can get the wave fields of sources and receivers by interpolation, and the intensity
(or amplitude) A
p
corresponding to the depth point P at travel-time t
P
=t
SP
+t
PR
can be found in seismograms. Ray equation migration is completed by transforming A
P
according to the specific relation, migrating it to the depth point, then calculating the ray fields of lots of sources and
receivers in the same way and finally stacking the outcomes. Numerical calculation has yielded satisfactory results. Data
processing of the Zhuangmu-Yuexi-Huangmei-Zhanggondu profile passing through the Dabie orogenic zone provides a structural
form of M-discontinuity along the profile. The result shows that the high pressure metamorphic rock zone of South Dabie rock
mass is related to the uplifting of M-discontinuity here. "Mountain root" exists under North Dabie rock mass, which conforms
with gravity isostasy theory. The Xiaotian-Mozitan fault is a suture zone as a result of the collision of North China plate
with Yangtze plate, and extends through M-discontinuity. The abyssal fault near Liu’an is the extended eastern section of
the Luonan-Minggang fault, which is also confirmed here.
Contribution No. RCEG 96012, Research Center of Exploration Geophysics, SSB, China.
This project was supported by the National Natural Science Foundation of China and the Chinese Joint Seismological Science
Foundation. 相似文献
416.
1995年7月12日,在云南省西南部的孟连县以西中缅边境发生了一次Ms7.3强烈地震。震前,距震中280km以远的滇西实验场重力网红河断裂以西出现了重力异常,平均变化幅值达70×10^-8ms^-1,最大变化幅值达114×10^-8ms^-2,云南省地震工程研究所测量队重力组根据上述重力异常变化,对此次地震作了较好的中短期预测预报。 相似文献
417.
华南诸广山复式岩体中段花岗岩的碱交代蚀变 总被引:8,自引:0,他引:8
诸广山复式花岗岩体中段某大型铀矿田中的部分花岗岩广泛发育碱交代蚀变作用。据对313个碱交代蚀变花岗岩样品的岩石化学分析资料及岩相学研究结果表明,该地碱交代蚀变是以钠长石化为主的多阶段钾、钠叠加交代(即混合交代),蚀变强度大多较弱,局部可较强并生成二长石岩、钠长石岩等交代蚀变岩。测得该碱交代蚀变岩石的Rb-Sr等时线年龄为132.1±5.8Ma,在时序上它与主体侵入的似斑状黑云母花岗岩(Rb-Sr等时线成岩年龄为215.2±6.3Ma)、补体侵入的细粒少斑黑云母花岗岩(测得Rb-Sr等时线成岩年龄为155.2±5.45Ma)构成一连续演化序列,推测碱质可能源自该产铀花岗岩岩浆演化钠转折分异阶段的产物;该蚀变岩属铀成矿前已遭剥蚀的钨、锡矿化矿根相,成为随后工业铀矿化(U-Pb法测得成矿年龄为103.2±0.6Ma)的有利围岩。 相似文献
418.
灌浆技术在岭澳水库防渗处理中的应用 总被引:1,自引:1,他引:0
介绍了灌浆技术在岭澳水库防渗处理中的应用,论述了如何合理选用浆液水灰比以及在灌浆过程中单注量的变化规律。 相似文献
419.
Response of a westerly-trough rainfall episode to multi-scale topographic control in southwestern China
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Wei Luo Hanyue Yin Shuai Yang Yushu Zhou Lingkun Ran Baofeng Jiao Ziyang Lai 《大气和海洋科学快报》2022,15(3):100148
This study aims to quantify the response of a westerly-trough rainfall episode that occurred in summer 2020 to multi-scale topographic control in southwestern China, based on observations and numerical simulations. The multi-scale topography is composed of the Tibetan Plateau, Hengduan Cordillera (HC), and Sichuan Basin (SB). The westerly trough was characterized by southeastward deepening together with an in-phase propagating rainfall episode. By utilizing the results of numerical experiments, how the multi-scale topography impacted this westerly trough rainfall episode is explored. It is found that HC was the pivotal topographic factor affecting the southeastward extension of the trough and related rainfall, while SB accerelated the eastward movement of the westerly trough and changed the tilting direction of the trough line, thus further changing the location and orientation of precipitation. For extreme rainfall with intensity exceeding 10 mm h?1, a roughly threefold rise in the cover ratio (from 1.8% to 7.2%) and fourfold increase in the areal rainfall amount per hour occurred by removing the HC barrier, due to the strongest vorticity and long-distance transport capacity to potential vorticy mass accompanying the southeast-stretching trough. Our results quantitatively reveal a strong response of westerly trough rainfall to multi-scale topographic control in southwestern China, therefore serving as an important reference for future decision making and effective model improvement.摘要中国西南部地形复杂, 降水频发, 地形对降水的影响至关重要. 本文基于观测和数值模拟, 定量揭示了青藏高原, 横断山脉和四川盆地多尺度地形对该地区西风槽降水的影响. 发现横断山脉是影响槽东南伸展, 降水传播的关键地形要素, 而四川盆地可加速西风槽东移, 改变槽线倾斜方向, 进而改变降水的位置和方向. 对于极端降水事件, 移除横断山脉屏障后, 降水覆盖率约增加3倍 (从1.8%增至7.2%), 小时面雨量增强4倍. 这些研究, 可为地形复杂地区降水的未来预报决策和有效模式改进提供参考. 相似文献
420.
Degradation of dissolved chlorinated solvents using granular iron is an established in situ technology. This paper reports on investigations into mixing iron and bentonite with contaminated soil for in situ containment and degradation of dense nonaqueous phase liquid source zones. In the laboratory, hypovials containing soil, water, bentonite, iron, and free-phase trichloroethene (TCE) were assembled. Periodic measurement of TCE, chloride, and degradation products showed progressive degradation of TCE to nondetectable levels. Subsequently, a demonstration was conducted at Canadian Forces Base Borden near Alliston, Ontario, Canada, where, in 1991, a portion of the surficial aquifer was isolated and free-phase tetrachloroethene (PCE) was introduced. Using a drill rig equipped with large-diameter mixing blades, three mixed zones were prepared containing 0%, 5%, and 10% granular iron by volume. The bentonite was added to serve as a lubricant to facilitate injection of the iron and to isolate the contaminated zone. Analysis of core samples showed reasonably uniform distributions of iron through the mixed zones. Monitoring over a 13-month period following installation showed, relative to the control, a decline in PCE concentrations to virtually nondetectable values. Reaction rates in the laboratory tests were similar to those reported in the literature, while the rate in the field test was substantially lower. The lower rate may be a consequence of mass transfer limitations under the static conditions of the field test. Results indicate that mixing iron and bentonite into source zones may be an effective means of source-zone remediation, with the particular advantage of being relatively immune to effects of geologic heterogeneity. 相似文献