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81.
中国典型地带陆生等足类的区系研究   总被引:7,自引:0,他引:7  
陈国孝 《动物学报》2000,46(3):255-264
通过对我国5个典型地带(热带、亚热带、暖温带、高寒带)20个样点进行陆生等足类的调查采集,共发现陆生等足类11科、29属、72种。由于各地带自然环境明显不同,造成了物种分布上的差异,其中热睡亚热睦区种类最多,分别为38种和47种,两地带物种共占总种数的80%以上;曙带和温带地区仅发现9种,而高寒带由于平均气温在0℃以下,不利于陆生等足类的生存,故迄今仅发现2种。其区系特点为:(1)区系分布的地带性  相似文献   
82.
Engineering enzymes with improved catalytic properties in non-natural environments have been concerned with their diverse industrial and biotechnological applications. Immobilization represents a promising but straightforward route, and immobilized biocatalysts often display higher activities and stabilities compared to free enzymes. Owing to their unique physicochemical characteristics, including the high-specific surface area, exceptional chemical, electrical, and mechanical properties, efficient enzyme loading, and multivalent functionalization, nano-based materials are postulated as suitable carriers for biomolecules or enzyme immobilization. Enzymes immobilized on nanomaterial-based supports are more robust, stable, and recoverable than their pristine counterparts, and are even used for continuous catalytic processes. Furthermore, the unique intrinsic properties of nanomaterials, particularly nanoparticles, also confer the immobilized enzymes to be used for their broader applications. Herein, an effort has been made to present novel potentialities of multi-point enzyme immobilization in the current biotechnological sector. Various nano-based platforms for enzyme/biomolecule immobilization are discussed in the second part of the review. In summary, recent developments in the use of nanomaterials as new carriers to construct robust nano-biocatalytic systems are reviewed, and future trends are pointed out in this article.  相似文献   
83.
目的:对直接影响神经支架微观结构的关键因素进行分析,以确定制备不同孔径仿真支架的制备工艺。方法:用前期开发的神经支架制备工艺,应用不同浓度的醋酸浓度和冷淋速度制备仿真神经支架,以扫描电镜观察神经支架结构特征,以确定醋酸浓度和冷淋速度对神经支架内部结构的影响。结果:醋酸浓度和冷淋速度对神经支架内部结构具有重要影响。醋酸浓度为0mg/ml时,无法制备定向结构的神经支架,当醋酸浓度为1mg/ml、2mg/ml、3mg/ml和4mg/ml时,可制备轴定向仿真支架,并且神经支架的孔径随醋酸浓度增大而增大;当冷淋速度为1×10-5m/s、2×10-5m/s和5×10-5m/s时,所制备的仿真支架内部均呈明显的轴向微管结构,其中冷淋速度为2×10-5m/s时,其轴向微管结构排列最为有序、规律。当速度为1×10-6m/s,2×10-6m/s,5×10-6m/s以及1×10-4m/s时,所制备的材料内部微管结构走向无明显规律。结论:醋酸浓度和冷淋速度是影响神经支架内部结构的两个关键因素,通过改变醋酸浓度和冷淋速度可制备不同孔径的仿真神经支架。  相似文献   
84.
We studied the joint evolution of predator body size and prey-size preference based on dynamic energy budget theory. The predators’ demography and their functional response are based on general eco-physiological principles involving the size of both predator and prey. While our model can account for qualitatively different predator types by adjusting parameter values, we mainly focused on ‘true’ predators that kill their prey. The resulting model explains various empirical observations, such as the triangular distribution of predator–prey size combinations, the island rule, and the difference in predator–prey size ratios between filter feeders and raptorial feeders. The model also reveals key factors for the evolution of predator–prey size ratios. Capture mechanisms turned out to have a large effect on this ratio, while prey-size availability and competition for resources only help explain variation in predator size, not variation in predator–prey size ratio. Predation among predators is identified as an important factor for deviations from the optimal predator–prey size ratio.  相似文献   
85.
本试验以转化CMV CP和TMV CP基因的转基因线辣椒纯合系植株作为研究试材 ,比较了单独或混合接种CMV和TMV后 ,转化线辣椒的抗病性表达特点 ,并测定了两种病毒在植株体内的病毒含量。结果表明 :转化线辣椒不仅能抵抗CMV和TMV的单独侵染 ,而且还能抵抗CMV和TMV的复合侵染。转化线辣椒表现为系统症状延迟出现 7 15d ,显症株率和病害严重度级别大幅度降低 ,CMV和TMV在接种叶、新生叶中的病毒含量明显减低。转基因线辣椒原生质体作为研究试材接种CMV ,测定病毒含量结果表明 :CMV病毒的增殖在转基因线辣椒原生质体内受到明显抑制。在CMV接种浓度为 4 0 μg/mL ,感染原生质体 4 8h后 ,CP(- )植株原生质体内CMV是CP( )的 4 .2倍。这一结果揭示了转基因线辣椒具有抑制病毒增殖的抗病性。  相似文献   
86.
祁连山西段草地土壤温度、水分变化特征   总被引:9,自引:0,他引:9  
研究土壤水热要素对合理预测祁连山气候变化特征及建立气候预警系统有重要意义。采用18套土壤温、湿度自动记录仪(HOBOU30)对祁连山西段草地进行3a连续定位监测,旨在探索分析该区土壤水热变化特征,阐明土壤水热互作效应及耦合机制。表明:1)冷期(1—3、11—12月)占全年的42%,暖期(4—10月)占58%;7月前土壤均温随月份增大而增大,月份增大1月土壤均温增大3.53℃,水分增大3.23%;7月后随月份增大而减小,月份增大1月土壤均温降低4.73℃,水分下降2.55%。2)日变化16:00前土壤均温为7.45℃,水分为16.26%,16:00后均温为9.1℃,水分为16.79%,16:00后比前均温高1.65℃,水分高0.54%。3)土温、水分与海拔均呈线性正相关,前者差异显著(P0.05),后者不显著(P0.05)。4)土温逐层(0—120 cm)平均递增0.07℃,水分递减0.58%;土温与土层深度呈显著线性正相关(P0.05,R2=0.99),水分呈显著线性负相关(P0.05,R2=0.97)。5)该区土温与水分呈显著线性负相关。因此,祁连山西段草地土温变幅较小,水分变幅大,两者在空间上变化均呈二次函数,时间上均呈一次函数。  相似文献   
87.
广东大瑶山维管植物区系的基本特征   总被引:3,自引:1,他引:3  
缪绅裕  王厚麟 《植物研究》2003,23(3):345-352
广东大瑶山地处南岭山脉南部的中亚热带地区, 25°11'18"N, 113°13'02"E,有野生维管植物1411种(含变种),隶属于194科701属。其中蕨类植物132种,所占比例较大,表明植物区系起源古老。区系表征科与植被优势科为壳斗科、山茶科、樟科、木兰科、金缕梅科、桑科、紫金牛科、山矾科等,说明该地域是华夏植物区系的重要组成部分。种子植物属的分布区类型中泛热带分布占优势,同时热带、温带区系成分均有不同程度地侵入,区系成分复杂,充分体现出其原始古老的自然性与植物种类的多样性。  相似文献   
88.
The activity concentrations of radionuclides in grape molasses soil samples collected from Zile (Tokat) plain in the Central Black Sea region of Turkey were measured by using gamma spectrometer with a NaI(Tl) detector. Also, the concentrations of 222Rn in soil samples and air were estimated essentially taking the activity concentrations of 226Ra measured in soil samples. Grape molasses soil samples with calcium carbonate content are used for sedimentation for making molasses in this region. The average activity concentrations of 232Th, 226Ra, 40K, and 137Cs were found as 62 ± 2, 68 ± 3, 479 ± 35, and 8.0 ± 0.3 Bq kg?1, respectively. The average concentrations of 222Rn in soil samples and air were estimated to be 50 kBq m?3 and 144 Bq m?3. From the activity concentrations, absorbed gamma dose rate in outdoor air (D), annual effective dose from external exposure (EE), annual effective dose from inhalation of radon (EI), and excess lifetime cancer risk (ELCR) were estimated in order to assess radiological risks. The average values of D, EE, EI, and ELCR were found to be 90 nGy h?1, 110 μSv y?1, 1360 μSv y?1, and 4 × 10?4, respectively.  相似文献   
89.
The life cycle and several life parameters of the zoophytophagous predator Engytatus varians (Distant) (Heteroptera: Miridae), including nymphal growth according to Dyar’s rule, were examined in the laboratory. The egg, nymph (five instars), and adult stages were 9.20, 17.36, and 19.02?d in length, respectively. The growth ratio for nymphs was consistent with Dyar’s rule based on the lengths of the femora of the forelegs, the tibiae and femora of the middle legs, and the antennae. Some biological characteristics of E. varians were also evaluated when the mirid was fed three different diets (B. cockerelli third instars, Sitotroga cerealella Olivier [Lepidoptera: Gelechiidae] eggs, and a mixture of both instars and eggs). The length of the nymphal stage was three days longer on a diet of only S. cerealella eggs than when the mirids were fed the third instars of B. cockerelli only or a mixture of both. The sex ratio was not affected by the type of diet. Nymphs of E. varians consumed B. cockerelli nymphs (80–85) when fed third instars only and third instars?+?S. cerealella eggs, respectively. The potential use of this predator as a biological control agent of B. cockerelli is discussed.  相似文献   
90.
饲料蛋白水平对宝石鲈生长和体组成影响研究   总被引:23,自引:2,他引:23  
选择体重一致、健康无病、初始体重104.13±0.46g宝石鲈105尾,随机分为5组,每组3重复,分别喂以蛋白水平为23.64%、28.45%、33.50%、3.04%和41.62%的等能颗粒饲料(以白鱼粉为蛋白源),在15口水泥池中控温养殖8周,研究饲料蛋白水平对宝石鲈生长和体组成的影响.饲养试验结果表明:饲料蛋白水平为33.50%时,宝石鲈的增重率最大,与饲料蛋白水平23.64%组相比差异极显著(P0.05).试验不同组间鱼体肥满度、肝体指数、蛋白质净利用率和饵料系数没有显著差异(P>0.05).通过增重率的折线法分析结果表明,宝石鲈获得最佳增重率的饲料蛋白需要量为33.94%.饲料蛋白水平对鱼体组成和肌肉成分研究表明,饲料蛋白水平为33.50%时鱼体蛋白含量最高,与蛋白水平23.64%组相比,差异极显著(P0.05).    相似文献   
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