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1.
为掌握黄海北部辽宁近岸海域鳀(Engraulis japonicus)产卵场的分布特征及其关键环境因子,基于2021年4—12月开展的产卵场综合调查获取的鳀样品及其鱼卵密度数据,运用Garrison重心分布法阐释鳀产卵洄游分布特征及其主产卵期;通过基于Tweedie分布的广义可加模型(generalized additive model, GAM)的构建,分析主产卵期内鳀卵密度与同步获取的海水表层温度(SST)、海水表层盐度(SSS)、海水表层叶绿素浓度(Chla)、浮游动物丰度(Fd)、浮游植物丰度(Fz)和深度(Depth)等6个环境因子,以及时间(月份,Month)和空间(经纬度、Lon和Lat)因子之间关系,并识别主控因子。结果显示,海域内鳀产卵期较长,由4月持续至11月,5—8月为主产卵期,其中,5—6月为产卵盛期。鳀产卵场规模和位置时空变化明显,时空因子与鳀卵密度分布呈密切非线性相关(累积偏差解释率为48.1%),(SST, SSS) (18.7%)和Depth (5%)次之。鳀产卵期适温范围较广,产卵场分布表现出高温高盐(低温低盐)增效作用和高温低盐限制作用。产卵初期(4月),鳀产卵场规模和鱼卵密度均较低,产卵重心位于海洋岛东南侧深水区;盛期(5月底—6月初)在SST主导下,鳀产卵场规模和鱼卵密度均至年内最高值,核心产卵场位于石城岛–庄河河口一带海域;此后,随着辽南沿岸水系盐度的下降,高温低盐的抑制作用使SSS因素主导产卵鱼群避开沿岸海域,鳀产卵场迁移至外海深水区,7月后位于30~50 m等深线之间;9—10月鳀繁殖活动基本结束,10月鳀卵仅零星分布于调查海域,直至12月未有鳀卵采获。研究可为黄海北部辽宁近岸海域鳀产卵场研究及鳀资源合理开发利用提供参考依据。  相似文献   
2.
普查镇江市黄墟镇104口浅井水质,并长期监测了其中7口的水质。结果表明:pH值超标率为11.5%,总硬度仅有1口超标,且氯化物含量较低,属中性软水和低度碱性硬水区域;氨氮超标率70.4%,为主要面源污染物;监测的七口井氨氮浓度在七、八月份和十一、十二月份比较高,COD随着时间的推移呈现增加趋势,氯化物含量很低,且与总硬度呈线性关系,凸现种植业污染特征。  相似文献   
3.
Reasons for performing study: Postural balance can be quantified using stabilographic variables derived from force plate data that describe movements of the horse's centre of pressure (COP) in the horizontal plane. Most force plates are not large enough to accommodate all 4 limbs of a standing horse, so the study was designed to assess whether representative stabilographic data could be collected from the forelimbs or hindlimbs. Objective: To determine whether stabilographic data from either the forelimbs or the hindlimbs were representative of data for the total body. Methods: Stabilographic data (960 Hz) were collected from 17 sound horses standing with the forelimbs and the hindlimbs on separate force plates. To increase variability in the data, horses were of different sizes, the recording duration was varied (15–60 s) and data were collected under sighted and blindfolded conditions. Results: Correlation matrices indicated that total body stabilographic variables were highly significantly correlated with both forelimb and hindlimb data but correlation coefficients were higher for forelimb data. Forward stepwise regression selected forelimb data for inclusion in the model for 15/16 variables, the exception being mean absolute mediolateral velocity. Conclusions: Ground reaction force data from a pair of limbs, preferably the forelimbs, can be used to measure variables that represent total body postural balance in sound standing horses. Potential relevance: Stabilographic data from either the forelimbs or hindlimbs may be useful for detecting and quantifying deficiencies in postural balance in ataxic horses.  相似文献   
4.
以宁夏盐池国家级草原资源生态监测站为依托,选择荒漠草原典型冰草植被类型的封育(5年)与未封育样地对地面节肢动物、植物以及土壤性质进行了调查,同时分析了地面节肢动物对封育后植物和土壤变化的响应。结果表明,封育对地表植被和土壤性质均产生了明显的影响,尤其是植物个体数、高度和盖度以及生物量封育样地显著高于未封育样地(P<0.05)。调查样地共捕获地面节肢动物7目26科28个类群;封育围栏内外共有的优势类群为拟步甲科琵甲属,共有的常见类群有13个类群,共有类群数占总类群数的50%。并且,地面节肢动物对封育亦产生了积极的响应,动物群落个体数、类群数和多样性封育样地均高于未封育样地,但均没有达到显著水平(P>0.05),说明荒漠草原短期封育(5年)对地表植被和地面节肢动物具有不同的生态效应。相关分析表明,地面节肢动物类群数和Shannon指数均与土壤容重呈显著负相关(P<0.05),而优势度指数与土壤容重呈显著正相关(P<0.05)。表明土壤容重是地面节肢动物群落结构封育内外差异的主要影响因素,而且不同地面节肢动物类群对封育内外生境的选择性而表现出不同的响应特征。  相似文献   
5.
6.
昆明草坪草混播配方优化组合模式探讨   总被引:1,自引:0,他引:1  
在昆明独特的气候条件下,通过对运动场草坪、观赏草坪和护坡草坪三类草坪混播配方的调查研究,探讨出了适应云南地区种植的9种优化组合。运动场草坪:草地早熟禾(Poapratensis L.)+高羊茅(Festucaarundinacea Schreb.)+多年生黑麦草(Lolium perenne L.),草地早熟禾+高羊茅,草地早熟禾+狗牙根(Cynodon dactylon(L.)Pers、)+多年生黑麦草;观赏草坪:草地早熟禾+匍匐翦股颖(Agrostisstolonifera L.),草地早熟禾+紫羊茅(Festuca rubraL.),草地早熟禾(优异)+草地早熟禾(蓝月)+草地早熟禾(新哥来得)+草地早熟禾(肯塔基);护坡草坪:高羊茅+多年生黑麦草+狗牙根,高羊茅+多年生黑麦草+狗牙根+白三叶(Trifolium repens L.),高羊茅+多年生黑麦草+狗牙根+白三叶+紫花苜蓿(Medicago sativa L.)。  相似文献   
7.
The study investigated the prevalence, concentration and characteristics of Salmonella spp. in the Irish beef chain. A total of 900 samples including bovine hides, carcasses and ground beef were examined for the pathogen over a 2‐year study (July 2007–June 2009). Salmonella prevalence was low in all sample types; bovine hide (0.75%, 3 of 400); carcasses (0.25%, 1 of 400); and ground beef (3%, 3 of 100). All positive samples contained the pathogen in low concentrations (<10 CFU per cm2 or per g). Serovars recovered were S. Dublin from hide and carcasses and S. Braenderup in ground beef. All isolates were susceptible to 13 anti‐microbials. The study highlights that Salmonella can be found at low levels at all stages of beef chain production, processing and retail and that there is a need for multiple hurdle interventions and practices along the beef chain, which will reduce consumer exposure to this pathogen.  相似文献   
8.
OBJECTIVE: Using force plate analysis (FPA), determine ground reaction forces in dogs with degenerative lumbosacral stenosis (DLS) and evaluate the effects of lumbosacral decompressive surgery. STUDY DESIGN: Prospective clinical study. ANIMALS: Twelve dogs with DLS. METHODS: DLS was diagnosed by clinical signs, radiography, computed tomography, and/or magnetic resonance imaging. FPA was performed before surgery, and 3 days, 6 weeks, and 6 months after surgery. The mean peak braking (Fy+), peak propulsive (Fy-), and peak vertical (Fz+) forces of 8 consecutive strides were determined. The ratio between the total Fy- of the pelvic limbs and the total Fy- of the thoracic limbs (P/TFy-), reflecting the distribution of Fy-, was analyzed to evaluate any changes in locomotion pattern postoperatively. Ground reaction force data for DLS dogs were compared with data derived from 24 healthy dogs (control). RESULTS: In dogs with DLS, the propulsive forces (Fy-) of the pelvic limbs were significantly smaller than those of controls. P/TFy- was significantly smaller in dogs with DLS than in control dogs, and increased during the follow-up period, reaching normal values 6 months after surgery. CONCLUSIONS: Cauda equina compression in dogs with DLS decreases the propulsive force of the pelvic limbs and surgical treatment restores the propulsive force of the pelvic limbs in a 6-month period. CLINICAL RELEVANCE: In dogs with DLS, FPA is an effective method in evaluating the response to surgical treatment. Normal propulsive force in the pelvic limbs was restored during 6 months after decompressive surgery.  相似文献   
9.
The investigation was conducted on client-owned moderately arthritic dogs with two objectives: (i) to evaluate therapeutic efficacy of type-II collagen (UC-II) alone or in combination with glucosamine hydrochloride (GLU) and chondroitin sulphate (CHO), and (ii) to determine their tolerability and safety. Dogs in four groups (n = 7-10), were treated daily for a period of 150 days with placebo (Group-I), 10 mg active UC-II (Group-II), 2000 mg GLU + 1600 mg CHO (Group-III), and UC-II + GLU + CHO (Group-IV). On a monthly basis, dogs were evaluated for observational pain (overall pain, pain upon limb manipulation, and pain after physical exertion) using different numeric scales. Pain level was also measured objectively using piezoelectric sensor-based GFP for peak vertical force and impulse area. Dogs were also examined every month for physical, hepatic (ALP, ALT and bilirubin) and renal (BUN and creatinine) functions. Based on observations, significant (p < 0.05) reduction in pain was noted in Group-II, III, and IV dogs. Using GFP, significant increases in peak vertical force (N/kg body wt) and impulse area (N s/kg body wt), indicative of a decrease in arthritis associated pain, were observed in Group-II dogs only. None of the dogs in any group showed changes in physical, hepatic or renal functions. In conclusion, based on GFP data, moderately arthritic dogs treated with UC-II (10 mg) showed a marked reduction in arthritic pain with maximum improvement by day 150. UC-II, GLU and CHO operate through different mechanisms of action, and were well tolerated over a period of 150 days.  相似文献   
10.
培养基质,赤霉素和硼对蕨菜孢子萌发成苗影响的研究   总被引:10,自引:1,他引:10  
为了提高蕨菜孢子人工培养成苗效率,对4 种培养基质和赤霉素(GA3)、硼3 种使用水平的孢子萌发成苗效果进行了研究。结果表明,森林土、琼脂和蛭石间原叶体数无差异,但成苗率间差异显著;森林土成苗率最高,达到42.86% ;砂基上孢子虽能萌发产生片状体,但不能发育到性器官形成期;赤霉素对孢子萌发生长具有显著的促进作用,在含有0.15×10- 7 g/L赤霉素培养基上成苗率较高;硼可提高配子体受精成苗,并以0.05% 硼酸处理效果最好;赤霉素与硼有显著的互作效应,含有0.15×10- 7 g/L赤霉素培养基上生长的原叶体,在性器官形成期喷施0.05% 硼酸,成苗率高达51.60% 。  相似文献   
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