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91.
对网围养殖区内草鱼的活动声涮进行了采集与分析.并将采集的声波进行了回放。结果表明.草鱼网围养殖区声波频率范围为0~3.2kHz.整个频段内没有宽带波峰。在草鱼饥饿、食饵和饱食的不同状态下养殖区内的水声特性有一定的差异。研究表明在网围养殖区通过声波回放能对草鱼起到诱集作用.在投饵回放、投饵不同放及不投饵回放声波的情况下,草鱼的响应时间分别为2.55、3.50、4.80min.存在显著差异。回放持续性声波和间隔性声波在响应时间上不存在显著差异。  相似文献   
92.
鲢鱼降血压肽的酶解条件   总被引:3,自引:0,他引:3  
以鲢鱼蛋白为原料,采用5种不同复合蛋白酶(P1,P2,P3,P4,P5)进行酶解。综合研究了复合生物酶酶量、酶解时间、pH、酶解温度等对鲢鱼蛋白酶解降血压肽ACE活性抑制效果的影响。结果表明。复合酶P1酶解降血压肽对ACE抑制率经体外检测为88.08%。具有最佳的酶解效果。对应最佳条件为:酶量25IU/mL,酶解时间2h,pH 7.0,酶解温度60℃。  相似文献   
93.
Ocean wave characteristics around New Zealand   总被引:1,自引:1,他引:0  
Nearly 17 years wave records from deep water and shore‐based stations are used to describe the ocean wave characteristics around New Zealand. The wave environment is dominated by west and southwest swell and storm waves generated in the temperate latitude belt of westerly winds. As a result, the west and south coasts are exposed, high energy shores, the east coast is a high energy lee shore, and the northern coast from North Cape to East Cape is a low energy lee shore sheltered from these winds and waves. South of New Zealand, wave energies are extremely high; the prevailing deep water wave is 3.5–4.5 m high and has a 10–12 s period, with a slight increase in wave heights in winter.

The west coast wave environment is mixed, and consists of locally generated westerly and southerly storm waves, and swell waves generated to the south. The prevailing wave is t.0–3.0 m and 6–8 s period. There are no strong seasonal rhythms, only shorter period cycles of wave height (5 day) associated with similar quasi‐rhythmic cycles in the weather.

The east coast also has a mixed wave climate with southerly swells, originating in the westerlies south of New Zealand, and locally generated southerly and northerly storm waves. The prevailing wave is 0.5–2.0 m and 7–11 s period. A short period rhythmic cycle, similar to that on the west coast, is superimposed on a weak seasonal cycle. The seasonal, cycle results from an increase in the frequency of local northerly waves in summer.

The prevailing wave on the north coast is a northeasterly, 0.5–1.5 m high and 5–7 s period. Subtropical disturbances and southward‐moving depressions generate a mixed wave environment and a possible seasonally reflecting a winter increase in. storminess.  相似文献   
94.
采用酸渍的方法制备鲢鱼鱼糜凝胶, 研究醋酸、柠檬酸、酒石酸等有机酸的浓度对酸渍鱼糜凝胶性质的影响。结果发现, 醋酸浸渍制备的鱼糜凝胶其TPA参数最高, 甚至超过传统的加热鱼糜凝胶。其中利用3%醋酸制备的鱼糜凝胶pH为4.3, 色泽比加热鱼糜凝胶白, 但持水性能较差。SDS-PAGE分析结果显示, 制备的酸渍鱼糜凝胶的主要蛋白组分与加热鱼糜凝胶类似。酸渍鱼糜凝胶经体外模拟胃肠液二相消化后, 发现90%以上的蛋白可以被消化。本研究结果表明, 利用酸渍方法可以制备新型的淡水鱼糜制品。  相似文献   
95.
Three artificial gynogenetic clones of silver carp were produced for the analysis of restriction enzyme digestion patterns of ND5-ND6 region from mtDNA of the clones. It is revealed that all intraclonal individuals shared completely the same digestion patterns but among interclonal individuals did not. The three clones were mixed and cultured in a pond together for two years, and restriction endonuclease digestion patterns of ND5–ND6 were used as genetic markers to assess the growth performance of each clone. Project supported by the National Natural Science Foundation of China (No. 39830300).  相似文献   
96.
建鲤与黄河鲤的RAPD分子标记及其杂交优势的遗传分析   总被引:3,自引:0,他引:3  
利用RAPD技术对建鲤、黄河鲤及其杂交子代进行了遗传分析,筛选的33个引物共扩增出155条带,其中多态性片段为105条,片段S18-1600、S472-300具有种的特异性,可作为鉴别建鲤与黄河鲤的分子遗传标记。建鲤、黄河鲤及其正、反交子代群体内的遗传相似系数分别为0.8240、0.7921、0.7920、0.8569,黄河鲤与正交F1具有较高的遗传变异水平,反交F1变异最小。正交F1、反交F1与亲本(建鲤、黄河鲤)的遗传距离分别为0.2233、0.2436、0.1749、0.2026,说明子代均继承了较多的建鲤的遗传物质。分析了子代与亲本的RAPD标记类型以及各类型的条带数。应用PIT标记系统测定了子代的杂种优势并探讨了优势产生的遗传机理。  相似文献   
97.
本文对高产养鱼池塘中白鲢鱼苗鱼种阶段的生长特性和规律进行了研究。经统计分析表明:1、白鲢鱼苗鱼种阶段的生长过程中,全长和时间的关系均呈直线相关(L=a bt)。鱼种全长以7-8两月生长最快。日增长率、瞬时增长率以鱼苗阶段居高,鱼种阶段次之。2、白鲢鱼苗阶段体重和时间呈指数相关(W=ae~(bt)),体重生长之速度(dw/dt)和加速度(d~2w/dt~2)与时间成正比。3、鱼种阶段体重与时间呈“S”形曲线相关(W=K/1 ae~(-bt)),体重的生长则以7~9月间最快。生长曲线拐点在t=-1n(1/a)/b;W=k/2。体重生长之速度和加速度分别呈“正态”和“正弦”曲线形。日增重率、瞬时增重率和相对增重率亦以鱼苗阶段较大,鱼种阶段次之。  相似文献   
98.
草鱼外周血淋巴细胞体外转化诸因素的研究   总被引:8,自引:0,他引:8  
于1993年3月-1993年11月,采自^3H-TdR同位素掺入法,分别测定草鱼外周血中淋巴细胞在经两种特异有丝分裂植物凝集素(PHA)与金黄色葡萄球菌蛋白A(SPA)刺激后发生的T淋巴细胞与B淋巴细胞应答转化的平均刺激指数(SI)的值,经不同浓度的PHA与SPA刺激的T,B淋巴细胞转化实验表明,两种有丝分裂原促T,B淋巴细胞应答转化的最适剂量,PHA为500μg/ml,SPA为0.05%,用不同  相似文献   
99.
The lake investigated (Lake Heiliger See near the town of Angermünde, North-East Germany) is small (10.2 ha) but deep (zmax = 12 m, ? = 6.5 m). During summer the thermocline is at a depth of 4-5 m, and the hypolimnion is filled with H2S already by mid-June, making 60-75% of the bottom area inaccessible to fish. The native fish fauna is dominated by planktivorous roach (Rutilus rutilus). A test stocking of silver carp (Hypophthalmichthys molitrix) together with an unplanned and erroneous stocking of common carp (Cyprinus carpio), coupled with an incorrectly calculated strong stocking of eel (Anguilla anguilla), which assumed that the total lake area yielded fish food organisms, brought about a strong depression of the food biomass available to native fish. Both silver carp and common carp showed a pattern of behaviour which only partly agreed with results obtained in experimental ponds prior to lake stocking. At least for 10 years there was a very low zooplankton biomass (mostly below 1 mg/l fresh weight) caused by silver carp and a strongly reduced benthos biomass (frequently below 1 g/m2 fresh weight) caused by common carp and eel on H2S-free bottom areas. Despite this extreme situation, which lasted for 20 years and is rarely found in lakes elsewhere, it was not possible to demonstrate negative effects on the native fish fauna comprising 16 species. Also the dominance pattern seems uninfluenced in the long run. A strong decline of the catchable roach stock was observed for some years, but the stock reappeared soon in comparable quantity. During the time of roach stock depression the individual growth of roach (and common carp) was particularly low. Nevertheless, roach succeeded in reproduction during this time in spite of the reduced zooplankton and detritus concentrations. Fry numbers per year ranged from 500-15 000 individuals/ha. The pike perch (Stizostedion lucioperca) was perhaps the most endangered species of all those living at small population numbers in the lake, since its fry is confined to the limnion where competition from silver carp and adult roach and perhaps predation by roach is highest. However the pike perch stock remained unchanged at the low level of 1950, the time prior of carp and eel stocking. All other rare species of Lake Heiliger See spawn in the littoral zone where fry survival conditions were less impacted. In summary, we present more evidence that the fish fauna of cyprinid lakes is more robust than in salmonid lakes. The regulation capacity of fish communities of eutrophic lakes seems to be able to offset even severe direct and indirect influences of fisheries management.  相似文献   
100.
在营养物供给量较大的实验条件下,鲢、鳙放养明显地改变了微型生态系统的群落结构、代谢和理化环境,以致实验后期鳙单养和鲢、鳙混养系统出现不同程度的富营养化。微型生态系统中浮游植物密度的增长不完全由营养级联效应所致,但初级生产力的组间差异可大致依据营养级联假说来解释。实验结果认为,以提高鱼产量为目标的鲢、鳙高密度放养,对加速营养物来源丰富的天然水域的富营养化起着重要的作用。  相似文献   
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