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1.
于2017年5和6月以及9和10月在怒江西藏段收集了怒江裂腹鱼(Schizothorax nukiangensis)194尾、裸腹叶须鱼(Ptychobarbus kaznakovi)152尾,热裸裂尻鱼(Schizopygopsis thermalis)117尾。综合运用3种多元分析方法分析3种鱼类摄食及消化器官形态的种间差异,结果显示,主要种间差异部位为头部及肠道;种间形态指标均为显著性差异(P <0.05);3种裂腹鱼的头部形态已有了一定程度的分化。鱼类食物组成及食物竞争情况研究表明,怒江裂腹鱼和裸腹叶须鱼属杂食性偏动物食性鱼类,两者食物重叠指数较高(0.91);热裸裂尻鱼属杂食性偏植物食性鱼类。食物多样性指数的种间差异明显。3种裂腹鱼营养及空间生态位均有分化,摄食与水温、流速和海拔等环境因素密切相关。  相似文献   

2.
中国淡水硅藻新记录——偏肿内丝藻兴凯变种   总被引:1,自引:0,他引:1  
于2016年5月对浙江省仙居国家公园进行藻类多样性调查时,发现了中国淡水硅藻的1个新记录种——偏肿内丝藻兴凯变种[Encyonema ventricosum var.hankensis(Skvortzov) RodionovaPomazkina]。该文采用光镜和扫描电镜对偏肿内丝藻兴凯变种浙江种群的形态特征进行了观察和描述,并将其与该种的其他地理种群及内丝藻属其他相似物种的形态特征进行比较,同时讨论了该物种的生境特征。结果表明:(1)偏肿内丝藻兴凯变种壳面均具明显背腹之分,背缘明显拱起,腹缘轻微波曲;端部呈头状至喙状。(2)偏肿内丝藻兴凯变种浙江地理种群在背部中央区域具一孤点,而其兴凯种群对孤点这一特征未有描述。(3)偏肿内丝藻兴凯变种在俄罗斯的兴凯湖和贝加尔湖等地有分布,该种在中国是首次报道。  相似文献   

3.
酸碱微环境对三种黄瓜主要真菌病原菌的影响   总被引:3,自引:0,他引:3  
王莉  李宝聚  石延霞 《生态学报》2005,25(4):808-813
以引起黄瓜灰霉病(Botrytis cinerea)、黑星病(Cladosporium cucumerium)、霜霉病(Pseudoperonospora cubensis)的3种真菌病害病原菌为代表,通过对病菌栖息微环境酸碱度的调节,达到控制病害的目的。研究看出,黄瓜的3种主要病害病原菌在p H=3.4~10 .4间孢子萌发和致病力表现基本一致:偏酸性环境(p H=4 .2~6 .2 )促进孢子萌发率和致病力增强而偏碱性环境(p H=7.5~10 .4 )则对其明显抑制;降低叶面微环境的酸度,大大减轻了病害的发生、扩展,特别是对黄瓜灰霉病菌的防治有明显效果  相似文献   

4.
大、小鼠是生物学和医学中常用的实验动物,其面神经核的形态和发育有不少人进行过研究,本文就收集到的有关这方面文献中的一些问题作一简要综述。 (一)面神经核的位置、形态、细胞分群及分群与外周面神经分支、分布的关系 大、小鼠面神经核位于延髓腹外侧部。呈吻尾稍长,背腹扁的椭圆体。大鼠面神经核吻尾长约1.6 mm(1.70 mm或1.55mm),平均体积约1.293mm~3;小鼠面神经核吻尾长约0.56mm。面神经核发出纤维走向背内侧偏吻侧,这些纤维在外展神经核的外侧偏背方形成面神  相似文献   

5.
怒江上游三种裂腹鱼类摄食及消化器官比较研究   总被引:1,自引:0,他引:1  
于2017年5和6月以及9和10月在怒江西藏段收集了怒江裂腹鱼(Schizothorax nukiangensis)194尾、裸腹叶须鱼(Ptychobarbus kaznakovi)152尾,热裸裂尻鱼(Schizopygopsis thermalis)117尾。综合运用3 种多元分析方法分析3 种鱼类摄食及消化器官形态的种间差异,结果显示,主要种间差异部位为头部及肠道;种间形态指标均为显著性差异(P < 0.05);3种裂腹鱼的头部形态已有了一定程度的分化。鱼类食物组成及食物竞争情况研究表明,怒江裂腹鱼和裸腹叶须鱼属杂食性偏动物食性鱼类,两者食物重叠指数较高(0.91);热裸裂尻鱼属杂食性偏植物食性鱼类。食物多样性指数的种间差异明显。3种裂腹鱼营养及空间生态位均有分化,摄食与水温、流速和海拔等环境因素密切相关。  相似文献   

6.
【目的】测定华丽肖蛸Tetragnatha nitens和锥腹肖蛸Tetragnatha maxillosa在实验条件下的耐饥力,确定其龄期与耐饥力之间的关系,为稻田害虫综合防治提供理论依据。【方法】实验条件:不供食物、实验温度为25℃,在人工气候箱内饲养并饥饿华丽肖蛸和锥腹肖蛸的幼蛛及成蛛。华丽肖蛸和锥腹肖蛸根据龄期分别设置3个处理组以及与每个处理组对应的对照组,每3 d统计死亡率。【结果】饥饿状态下华丽肖蛸和锥腹肖蛸的存活时间与体重之间相关性是极显著的;华丽肖蛸和锥腹肖蛸各自3个不同龄期组的存活时间具有极显著差异;华丽肖蛸和锥腹肖蛸对应的3个相同龄期组的存活时间无显著差异;不同龄期组幼蛛的阶段成活率与存活时间之间符合二次抛物线关系。用拟合曲线得出华丽肖蛸的饥饿半致死时间(t50)和致死时间(t95)分别为22 d和32 d;锥腹肖蛸的饥饿半致死时间(t50)和致死时间(t95)分别为20 d和28 d。【结论】华丽肖蛸和锥腹肖蛸的幼蛛在没有食物的实验条件下,具有一定的耐饥饿能力,仍可存活一定的时间。  相似文献   

7.
为了解雅砻江中游支流力丘河的鱼类多样性现状及栖息地保护价值,于2019年9月和2020年6月、11月在力丘河11个采样点进行了3次鱼类资源调查,共采集鱼类2 557尾,隶属于2目4科9属13种。西溪高原鳅Triplophysa xiqiensis、软刺裸裂尻鱼Schizopygopsis malacanthus、短须裂腹鱼Schizothorax wangchiachii和齐口裂腹鱼Schizothorax prenanti数量较多、分布较广,其余种类仅有零星分布。丰度/生物量比较曲线表明,力丘河鱼类群落受到中等程度干扰。Spearman秩相关性系数显示,鱼类多样性与海拔呈显著负相关。非度量多维标度分析表明,不同海拔区域的鱼类群落空间结构差异显著,雅砻江干流的许多鱼类仅分布到力丘河下游普沙绒乡罗让以下河段,力丘河中游甲根坝乡以上河段及塔拉沟、色物绒沟等支流仅分布有西溪高原鳅和软刺裸裂尻鱼。由于相对较低的鱼类多样性、严酷的生态环境和海拔对鱼类分布的限制,力丘河作为雅砻江中游干流水电开发后鱼类栖息地的保护价值将一定程度降低,建议同时考虑雅砻江干流鱼类栖息地的保护。  相似文献   

8.
在初中生理卫生神經系统一章的实驗很多,現就我在做脊髓的反射实驗中的一点体会介紹出来: 1.做实驗用的蛙(或蟾蜍)应是新鮮的、有充沛的生活力,若捉来的蛙放的时間較長,或加以撫弄,会使实驗达不到预期效果。 2.在切除腦顱时,应先用湿手巾將蛙体包住,仅使头部露在外面,这样,一方面不妨碍行手术,  相似文献   

9.
本文通过研究微型裸腹溞的生活史,探讨了当东湖养殖的鲢鳙密度进一步增大时,它们释放的化学信息素对微型裸腹溞的间接作用,同时也讨论了微型裸腹溞在高密度鱼类捕食下种群能够延续的可能机制。在淡水生态系统中,无视力的生物能通过化学物质的交流来感知环境中的捕食压力,从而作出相应的调整策略。本研究结果显示高浓度的鱼类化学信息素对微型裸腹溞的生活史并没有显著影响,意味着微型裸腹溞有可能通过与该鱼类的长期共存而适应了这类物质。但是我们的结果与前人的相比还是存在着很大的差异,尤其是明显提高的总的后代数、平均怀卵量和内禀增长力;另外短的世代时间、小的初次繁殖时的体长和年龄有可能也是微型裸腹溞在高密度鱼类捕食压力下占优势的良好证据。  相似文献   

10.
本文选择鳃虱科Bopyridae的47个形态学性状,利用PAUP软件,以支序分析方法对中国海域鳃虱科22属38种进行种间系统发育关系研究。支序分析结果较好地反映了鳃虱科内姐妹群的关系。根据分析结果,鳃虱科中较早分出的物种为假鳃虱亚科巨鳃虱属中的日本巨鳃虱Gigantione ishigakiensis;较晚分化出来的物种是背腹虱亚科腹虱属的日本腹虱Athelges takanoshi mensis和假盖腹虱属的日本假盖腹虱Pseudostegias setoensis,种间姐妹群关系为:假鳃虱亚科中偏寄居蟹鳃虱属的球足偏寄居蟹鳃虱Asymmetrione globifera与仿偏寄居蟹鳃虱属的疣缘仿偏寄居蟹鳃虱Parasymmetrione tuberculineata为姐妹群,假鳃虱亚科扁蝼蛄虾鳃虱属中的卵圆扁蝼蛄虾鳃虱Gyge ovalis与福建扁蝼蛄虾鳃虱Gyge fujianensis为一对姐妹群,蟹鳃虱亚科指突鳃虱属中的霍氏指突鳃虱Dactylokepon halthuisi与蝼蛄虾鳃虱属的双突蝼蛄虾鳃虱Upogebione bidigitatus为一对姐妹群,多疣蟹鳃虱属的分节多疣蟹鳃虱Onkokepon articulatus与北部湾多疣蟹鳃虱O.beibuensis为一对姐妹群,异节蟹鳃虱属的单异节蟹鳃虱Allokepon monody与长尾异节蟹鳃虱A.longicauda为一对姐妹群。  相似文献   

11.
心脑血管疾病大额住院消费统计分析   总被引:1,自引:1,他引:0  
通过对医院2004-2006年心脑血管疾病大额住院消费(消费大于50000元,以下简称大额消费)病例发病率高的前五种疾病的构成情况、药费、材料费消耗情况进行分析,认为加强大额病例中发病率高的病种的重点管理,是降低医疗费用的有效途径。建议制定常见病大额病种预定额付费方案和审查报销制度;采用适宜技术;控制药费,防止过度医疗,有效地遏制医疗费用的过快增长。  相似文献   

12.
Although the architecture of tripartite multiple drug resistance (MDR) efflux pumps of Gram-negative bacteria has been well characterized, the means by which the components recognize each other and assemble into a functional pump remains obscure. In this study we present evidence that the C-terminal domain of the Pseudomonas aeruginosa OprM and the α-helical hairpin domain of Vibrio cholerae VceA play an important role in the recognition/specificity/recruitment step in the assembly of a functional, VceAB-OprM chimeric efflux pump. To our knowledge, this is the first evidence directly linking the C-terminal domain of an outer membrane efflux protein to its recruitment during the assembly of a tripartite efflux pump.  相似文献   

13.
对不同地理分布的猪苓纯培养菌株进行了种性和酯酶同工酶的比较研究,结果表明,鸡爪苓(Z)纯培养菌株和猪屎苓(ZJ)纯培养菌株的种性有很大不同,两个纯培养菌株的酯酶同工酶酶带类型差异较大,亲缘关系较远。  相似文献   

14.
New analogues of the Gly-Pro-Arg and Arg-Gly-Asp fragments of fibrinogen were synthesized: Gly-Pro-Arg-Pro (I), Gly-Pro-Arg-Pro-Met-OMe (II), Gly-Pro-Arg-Pro-Phe (III), Gly-Pro-Arg-Pro-Asp (IV), Gly-Pro-Arg-Pro-Glu (V), and Arg-Asn-Trp-Asp (VI). Their effect on the activity of proteases of various types was studied with the method of lysis of fibrin plates. All the peptides were found to inhibit plasmin activity (by 60–85%) and the γ-subunit of nerve growth factor (by 55–93%). Tetrapeptide (VI) proved to be an effective inhibitor of tissue activator of plasminogen and the γ-subunit of nerve growth factor (by 96 and 93%, respectively). The peptides exerted practically no effect on the activity of urokinase and moderately inhibited the activity of streptokinase [(III), IV), and (VI)], papain [(I), (II), IV), and (VI)], subtilisin [(V) and (VI)], α-chymotrypsin [(III), (V), and VI)], and Bacillus subtilis metalloprotease (VI). They inhibit trypsin [except for (I) and (III)] when applied on fibrin plates at a concentration of 1 × 10?2 M, while, at the concentration of 1 × 10?3 M, (I) and (II) induced an increase in proteolytic activity by 35 and 47%, respectively.  相似文献   

15.
J.Michael Gould  S. Izawa 《BBA》1974,333(3):509-524
1. By using dibromothymoquinone as the electron acceptor, it is possible to isolate functionally that segment of the chloroplast electron transport chain which includes only Photosystem II and only one of the two energy conservation sites coupled to the complete chain (Coupling Site II, observed P/e2 = 0.3–0.4). A light-dependent, reversible proton translocation reaction is associated with the electron transport pathway: H2O → Photosystem II → dibromothymoquinone. We have studied the characteristics of this proton uptake reaction and its relationship to the electron transport and ATP formation associated with Coupling Site II.

2. The initial phase of H+ uptake, analyzed by a flash-yield technique, exhibits linear kinetics (0–3 s) with no sign of transient phenomena such as the very rapid initial uptake (“pH gush”) encountered in the overall Hill reaction with methylviologen. Thus the initial rate of H+ uptake obtained by the flash-yield method is in good agreement with the initial rate estimated from a pH change tracing obtained under continuous illumination.

3. Dibromothymoquinone reduction, observed as O2 evolution by a similar flash-yield technique, is also linear for at least the first 5 s, the rate of O2 evolution agreeing well with the steady-state rate observed under continuous illumination.

4. Such measurements of the initial rates of O2 evolution and H+ uptake yield an H+/e ratio close to 0.5 for the Photosystem II partial reaction regardless of pH from 6 to 8. (Parallel experiments for the methylviologen Hill reaction yield an H+/e ratio of 1.7 at pH 7.6.)

5. When dibromothymoquinone is being reduced, concurrent phosphorylation (or arsenylation) markedly lowers the extent of H+ uptake (by 40–60%). These data, unlike earlier data obtained using the overall Hill reaction, lend themselves to an unequivocal interpretation since phosphorylation does not alter the rate of electron transport in the Photosystem II partial reaction. ADP, Pi and hexokinase, when added individually, have no effect on proton uptake in this system.

6. The involvement of a proton uptake reaction with an H+/e ratio of 0.5 in the Photosystem II partial reaction H2O → Photosystem II → dibromothymoquinone strongly suggests that at least 50% of the protons produced by the oxidation of water are released to the inside of the thylakoid, thereby leading to an internal acidification. It is pointed out that the observed efficiencies for ATP formation (P/e2) and proton uptake (H+/e) associated with Coupling Site II can be most easily explained by the chemiosmotic hypothesis of energy coupling.  相似文献   


16.
林带阻力系数与透风系数关系的理论分析   总被引:15,自引:2,他引:13  
根据冲量定理分析了林带对气流的阻力,首次得到了林带阻力系数的估算模式(Cd=(1.8+0.2α)(1-α)sin2ω,并利用有关文献发表的资料进行了验证.文章还对来流平行林带时林带对气流的阻力进行了讨论,指出来流平行林带时林带对气流的阻力仅为来流垂直林带时林带对气流阻力的0.7—1.1%,可以不予考虑.  相似文献   

17.
该研究于西藏自治区东南部的东达山高山草甸沿生境干旱化梯度设置10个样地,采用线性回归方法分析优势种高山嵩草(Kobresia pygmaea)和矮生嵩草(K.humilis)叶片数量与其它构件数值(分株数量、茎基直径、根系数量和根系长度)之间的关系,并采用线性回归斜率测度分株功效、叶片萌生能力、根系分生功效和根系伸长功效,以探讨嵩草的分株能力、茎基生长和根系生长对生境干旱化过程的响应机制。结果显示:(1)2种嵩草植物的叶片数量与4种构件数值均为显著线性正相关关系。(2)随着生境干旱化程度增加,高山嵩草分株数量增加,矮生嵩草分株受干旱抑制程度高,分株数量呈下降趋势;2种嵩草分株功效下降,即单株叶片数量因干旱化程度增加而减少。(3)2种嵩草的茎基直径、叶片萌生能力随着生境干旱化程度增加而下降;高山嵩草叶片萌生能力的变化与生境干旱化梯度一致,具有连续性;矮生嵩草叶片萌生能力对生境干旱化的适应性弱,干旱到一定程度发生骤降。(4)随着生境干旱化,高山嵩草的根系数量和长度均增加,矮生嵩草根系长度增加,但数量却无规律变化;2种嵩草的根系分生功效和根系伸长功效均下降。研究表明:嵩草属植物分布的最适宜生境为表面稍有积水的沼生生境。为适应生境干旱化,高山嵩草降低叶片萌生率以减少蒸腾作用,增加分株数量以增强对空间的占有能力,并增加根系数量和长度来提高对土壤水分的吸收能力,因此对干旱有较强适应性且分布范围广;矮生嵩草只通过降低叶片萌生率,增加根系长度响应干旱化生境,其分布范围较窄。  相似文献   

18.
The role of Hemipteran saliva and salivary enzymes is central to an understanding of the etiology of damage that these insects cause to plants. The dilute nature of the salivary secretions and the minute quantities in which they are often obtainable have made analysis and detection of salivary components very difficult. Such investigations in this laboratory have led us to formalise the techniques involved and we believe that the compilation of these methods presented herein may be useful to other research workers in this area. Methods are described for acid and alkaline phosphatase, esterase, /S-glucosidase, carbohydrases, invertase, amylase, proteinase, pectinase, cellulase, catalase, peroxidase, catechol oxidase, superoxide dismutase and ascorbic oxidase.  相似文献   

19.
民勤绿洲边缘地下水位变化对植物种群生态位的影响   总被引:3,自引:0,他引:3  
在民勤绿洲边缘,利用空间区域不同地下水位(湖区8~12m,泉山区15~17m,坝区20~23m)和时间序列(1984~1992年)民勤沙井子地区地下水位下降(7.45~11.65m)梯度,研究地下水位下降对荒漠植物种群生态位的影响。结果表明:空间区域地下水位下降,植物种群生态位宽度均减小,种群退化;时间序列地下水位下降,白刺种群在扩展,其它植物种群在退化。白刺种群生态位宽度在民勤绿洲边缘荒漠植物群落中最大,是该区的建群种。由于白刺种群在地下水位7.45~11.65m范围内扩展,民勤绿洲生态环境治理中地下水位达到该范围是一个主要目标。  相似文献   

20.
For factorial experiments with unbalanced data the method of unweighted means is an alternate method of analysis which is computationally simpler than likelihood ratio based F-tests. The quality of the null approximation to the F-distribution of the statistic for the method of unweighted means and the power of this test relative to the likelihood ratio test are discussed. Recommendations are made of when in the course of data analysis the superior operating characteristics of the likelihood ratio test may not outweigh the computational simplicity of the method of unweighted means test.  相似文献   

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