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1.
Li QM  Zi XZ  Yu XC 《应用生态学报》2011,22(8):2061-2068
对山东省泰安市下挖0、0.5、1.0、1.5m节能日光温室(不同下挖深度温室的结构参数完全一致)太阳直射辐射能截获量进行分析,研究了2009年12月20日—24日(冬至日前后)和2010年6月19日—23日(夏至日前后)温室环境因子日变化规律及其空间分布特点.结果表明:随着下挖深度的增加,下挖壁面在温室内的阴影面积逐渐增加,进入室内的太阳直射辐射逐渐由南向北迁移,地面辐射/后墙辐射值逐渐减小;日光温室下挖深度在0~1.0m时,下挖越深,温室气温和地温增温效果越显著、保温效果越好,下挖深度达1.5m时增温效果则显著下降、最低地温偏离度增大;下挖越深,温室内光照度越低、相对湿度越大.兼顾温室的采光与保温性能,泰安地区10m跨度的下挖式日光温室的适宜下挖深度应不超过1.0m.  相似文献   

2.
黄土丘陵区沙棘灌木林地土壤水分动态研究   总被引:10,自引:2,他引:8  
采用生物与工程措施相结合的方法,定位研究了沙棘林地的土壤水分变化动态。结果表明:水平阶、水平沟和鱼鳞坑整地不同立体配置模式土壤水分大幅度提高,0~2.0m沙棘与豆科牧草立体配置的土壤含水量均高于沙棘与禾本科牧草的立体配置;2.0~5.0m沙棘与禾本科牧草立体配置的土壤含水量均高于沙棘与豆科牧草的立体配置。其提高幅度为3%~5%。未采用工程整地措施的沙棘林地,在沙棘生长的第3年,土壤干层的分布深度不甚明显;从第5年土壤干层厚度逐渐加深到1.8m;第7年土壤干层厚度为2.6m;第9年土壤干层厚度为3.1m;第11年土壤干层厚度为2.6m;第13年土壤干层厚度为2.2m。  相似文献   

3.
屋面绿化卷材根系层土壤温度变化特征   总被引:1,自引:0,他引:1  
根据3种厚度屋面绿化卷材根系层土壤温度、自然条件下的土壤温度和附近气象站大气温度观测资料,采用对比分析、线性回归等方法,对不同屋面绿化卷材根系层土壤温度的变化特征进行了研究。结果表明:屋面绿化卷材根系层土壤温度年变化规律与大气温度年变化规律基本一致;卷材具有一定的隔热保温作用,且随着薄膜厚度的增加,绿化卷材保温隔热效果越明显;不同型号卷材根系层土壤温度的日变幅随薄膜厚度的增加而减小;根系层土温日变幅与厚度关系可拟合成指数函数;不同厚度屋面卷材根系层土壤温度同大气温度之间均存在极显著的线性关系。  相似文献   

4.
应用光学显微镜、扫描电镜和透射电镜对安徽大学校内水池中眼子菜科植物菹草的花粉形态进行了观察和研究.结果表明花粉粒球形至近球形,花粉大小为21.0-29.0 μm,平均为24.5 μm.无萌发孔.光学显微镜下,花粉外壁纹饰为网状,外壁厚约4.1μm,两层明显,外层较内层厚.在扫描电镜下花粉表面具粗网状纹饰,网脊窄.在透射电镜下,花粉外壁为三层组成,即覆盖层、柱状层和基层.外壁内层不明显.覆盖层不连续,为半覆盖层;柱状层小柱发达;基层较厚.同时研究了菹草花粉的地理分布及其与生态因子的关系.根据菹草植物赖以生存的生态因子,得出菹草花粉分布区的主要生态因子,包括地理位置、海拔高度、年降水量、年积温及生境,为利用地层中眼子菜科化石花粉重建古气候、古环境及气候变迁提供了现代孢粉学资料和依据.  相似文献   

5.
采用Argo数据和中西太平洋渔业委员会的大眼金枪鱼延绳钓数据,绘制了温跃层和月平均单位捕捞努力量渔获量(CPUE)的空间叠加图,分析中西太平洋大眼金枪鱼渔场时空分布对温跃层的响应关系.结果表明: 全年中心渔场纬向主要分布在南北纬10°之间的低纬度区域.在赤道以南有季节性中心渔场的出现和消失,与温跃层上界温度、深度和温跃层厚度的积极性变化有关.中心渔场主要分布在温跃层上界较深(70~100 m)和厚度较大(>60 m)的海域,厚度小于40 m的区域难以形成中心渔场;适宜分布的上界温度区间在26~29 ℃,在此区间外CPUE多小于中心渔场阈值(Q3).中心渔场的空间分布随上界深度和跃层厚度的季节性变动而变动,当赤道以南海域的上界深度变浅以及厚度变薄时,中心渔场消失.温跃层下界温度、深度和温跃层强度季节性变化不显著,但与中心渔场出现有显著关系.中心渔场主要分布在温跃层下界深度两条高值带之间的区域,温度低于13 ℃以及强度大的区域;在温跃层下界深度超过300 m和小于150 m区域,下界温度超过17 ℃的区域,或者强度小的区域难以形成中心渔场.利用频次分析和经验累积分布函数计算其适宜温跃层特征参数分布,结果表明研究区域大眼金枪鱼适宜分布的上界温度、深度和下界温度、深度分别是26~29 ℃、70~110 m、11~13 ℃和200~280 m;适宜分布的温跃层厚度和强度分别是50~90 m和0.1~0.16 ℃·m-1.本研究初步得出研究区域大眼金枪鱼CPUE空间分布和温跃层的关系,为我国远洋金枪鱼捕捞作业和资源管理提供理论参考.  相似文献   

6.
利用扫描电子显微镜(SEM)和透射电子显微镜(TEM)观察了美乐多(Melodorum fruticosum)的花粉形态特征。美乐多花粉为球形或扁圆形的单粒花粉,外壁纹饰为微褶皱状,有点状凹陷,无任何萌发孔或萌发沟。花粉外壁由外壁外层包括覆盖层(连续)、覆盖下层、基足层(1~3层薄片层结构,偶断裂或扭曲至6~10层)和外壁内层(连续)组成。其中,覆盖下层,其厚度为整个花粉外壁厚度的1/2,为混合型结构,即小柱状和颗粒状同时存在,但以颗粒状为主。花粉内壁分为内壁外层和内壁内层,其厚度逐渐变薄。美乐多的花粉特征(单粒、无萌发孔或沟、覆盖层连续、基足层为薄片层结构、花粉外壁内层薄等)与紫玉盘族其他类群一致。  相似文献   

7.
光照强度对苹果果实表面温度变化的影响   总被引:3,自引:1,他引:2  
光照强度对于果实温度的变化具有重要影响。一天中 ,日落后和日出前 ,果实表面温度都接近气温。树冠外围暴露果实表面温度主要来源于气温和由于吸收光能后转化成热能所增加的温度。当光照强度较低和持续时间较短时 ,光照对果实表面温度的影响较小。不同月份光致果实温度增加的幅度有所不同 ,6~ 10月日光致最大果实温度的变化幅度范围为 14 .4 6~ 18.98℃。光照强度与光致果实增温具有极显著相关 ,其回归方程为 Y=0 .0 0 88x 6 .0 97,r=0 .4 3382 * * 。遮荫由于减少了果实表面接受的光能 ,因而可以明显降低果实表面的温度  相似文献   

8.
利用温室环境参数构建室内微环境模拟模型,并结合温室病害模型进行预警,便于开展病害生态防治,以减少农药使用,从而保护温室生态环境和保证农产品质量安全.本文利用温室内能量守恒原理和水分平衡原理,构建了日光温室冠层叶片温度和空气相对湿度模拟模型.叶片温度模拟模型考虑了温室内植物与墙体、土壤、覆盖物之间的辐射热交换,以及室内净辐射、叶片蒸腾作用引起的能量变化;相对湿度模拟模型综合了温室内叶片蒸腾、土壤蒸发、覆盖物与叶面的水汽凝结引起的水分变化.将温湿度估计模型输出值作为参数,输入黄瓜霜霉病初侵染和潜育期预警模型中,估计黄瓜霜霉病发病日期,并与田间观测的实际发病日期比较.试验选取2014年9月和10月的温湿度监测数据进行模型验证,冠层叶片温度实际值与模拟值的均方根偏差(RMSD)分别为0.016和0.024 ℃,空气相对湿度实际值与模拟值的RMSD分别为0.15%和0.13%.结合温湿度估计模型结果表明,黄瓜病害预警系统预测黄瓜霜霉病发病日期与田间调查发病日期相吻合.本研究可为黄瓜日光温室病害预警模型及系统构建提供微环境数据支持.  相似文献   

9.
南水青冈属及壳斗科其他属花粉壁超微结构比较研究   总被引:6,自引:1,他引:5  
对主要分布于南美和新西兰的南水青冈属Nothofagus 花粉外壁的超微结构进行了观察和研究, 同时与壳斗科其他属花粉外壁的结构进行比较,结果表明,南水青冈属花粉外壁的厚度、结构、萌发孔类 型以及花粉外壁表面的纹饰与壳斗科其他属花粉外壁的超微结构存在明显差别。主要表现为:南水青 冈属花粉外壁的柱状层和内层发育差,为颗粒状;基层和覆盖层无分化结构;覆盖层上为刺状纹饰;萌发 孔为5~8沟。壳斗科其他属花粉外壁的小柱发育好,形成明显的柱状层;覆盖层和基层常具一定的结 构;花粉表面较光滑,或为波状、颗粒或瘤状纹饰;内层发育较好;多数花粉具3孔沟,少数为3沟或3拟 孔沟。本研究认为南水青冈属花粉外壁的结构属于较原始类型,支持kuprianova等将南水青冈属独立为南壳斗科。  相似文献   

10.
盖裂木属两种植物花粉形态观察   总被引:1,自引:1,他引:0  
陈东钦  徐凤霞 《广西植物》2008,28(3):317-319
利用光学显微镜、扫描电镜和透射电镜观察了盖裂木属两种Talauma gloriensis和T.mexicana的花粉形态。花粉粒具远极单萌发沟,椭圆球形,外壁较光滑或略粗糙且具小穴状雕纹。在透射电镜下,花粉外壁可分为覆盖层、柱状层和基层,外壁-2明显,且厚度不均匀。在远极面萌发沟区域,外壁逐渐减薄,最后覆盖层和柱状层消失,仅残留基层。T.gloriensis的柱状层内部空间较小,多由颗粒组成,而T.mexicana柱状层中有发育较好的小柱,与覆盖层和基层连接。  相似文献   

11.
Studies of various biological tissues have shown that residual strains are important for tissue function. Since a force balance exists in whole wall thickness specimens cut radially, it is evident that layer separation is an important procedure in the understanding of the meaning of residual stresses and strains. The present study investigated the zero-stress state and residual strain distribution in a three-layer model of the pig oesophagus. The middle part of the oesophagus was obtained from six slaughterhouse pigs. Four 3-mm-wide rings were serially cut from each oesophagus. Two of them were used for separating the wall into mucosa-submucosa, inner and outer muscle layers. The remaining two rings were kept as intact rings. The inner and outer circumferences and wall thickness of different layers in intact and separated rings were measured from the digital images in the no-load state and zero-stress state. The opening angle was measured and the residual strain at the inner and outer surface of different layers and the intact wall were computed. Compared with intact sectors (62.8+/-9.8 degrees ), the opening angles were smaller in the inner muscle sectors (37.2+/-11.4 degrees , P<0.01), whereas the opening angles of mucosa-submucosa (63.9+/-6.8 degrees ) and outer muscle sectors (63.9+/-6.8 degrees ) did not differ (P>0.1). Referenced to the zero-stress state of the intact sectors, the inner and outer residual strains of the intact rings was -0.128+/-0.043 and outer residual strain was 0.308+/-0.032. Referenced to the "true" zero-stress state of separated three-layered sectors, the inner residual strain of intact rings were -0.223+/-0.021 (P<0.01) and 0.071+/-0.022 (P<0.01). Referenced to the "true" zero-stress state, the residual strain distribution of different layers in intact rings was shown that the inner surface residual strain was negative at mucosa-submucosa and inner muscle layers and was positive at outer muscle layer, whereas the outer surface residual strain was negative at the mucosa-submucosa layer and positive at the inner and outer muscle layers. For the separated different layered rings, the inner residual strain was negative and outer residual strain was positive; however, the absolute values did not differ (P>0.1). In conclusion, it is possible to microsurgically separate the oesophagus into three layers, i.e., mucosa-submucosa, inner muscle and outer muscle layers, the residual strain differ between the layers, and the residual strain distribution was more uniform after the layers were separated.  相似文献   

12.
扁绒泡菌孢子形成过程超微结构   总被引:1,自引:0,他引:1  
李艳双  于玲  王晓丽  李玉 《菌物学报》2011,30(1):138-141
诱导扁绒泡菌显型原质团形成子实体并观察在形成过程中孢囊的超微结构,结果表明,全部原质团参入形成孢子及孢丝;孢子形成初期原质团聚缩使原生质密度加大,脂滴密度也增加;液泡联合形成液泡网体分割原质团,孢子及孢丝一同形成;相邻孢子初始形成的孢子壁可见吻合的突起和凹陷,这是孢子成熟后的表面纹饰部分;孢子壁随孢囊发育逐渐达到适宜位置,孢子壁由透明内层及电子密度较大的外层组成;随后可见外有疣突,内含脂滴的圆形孢子。  相似文献   

13.
The rod-shaped rickettsia-like bacteria of Pierce's disease measure about 0.25 to 0.50 μm in diameter and 1.0 to 4.0 μm long. The bacteria have a cell wall consisting of a trilaminar outer membrane and two intermediate low-density layers separated by a dense intermediate layer. A trilaminar cytoplasmic membrane is also present, resulting in a total wall complex thickness of 25 to 40 nm. A periodic infolding of the outer membrane and intermediate layers of the wall give the wall surface a ridged apperance. The ridges appear to go around the long axis of the cell, possibly in the form of spirals. Ribosomes and nuclear regions with easily visible deoxyribonucleic acid strands and clumps are distributed throughout the cytoplasm. Binary fission, during which the cell wall and cytoplasmic membrane folded inward to partition the cell, was observed. In the xylem of infected grapes, the bacteria are either distributed evenly throughout the lumen of the xylem vessel or appressed along the inner surface of the vessel walls in an electron-lucent matrix.  相似文献   

14.
SYNOPSIS. Oocysts of Eimeria nieschulzi from the laboratory rat, Rattus, norvegicus , were studied by scanning and transmission electron microscopy. Oocysts had a rough outer wall with apparent random depressions. The oocyst wall is composed of 2 layers: an osmiophilic outer layer consisting of a rough external and smooth internal surface, and a relatively thick, electron-lucent inner layer. The outer layer is composed of a dense, coarsely granular matrix. The inner layer consists of homogeneous fine granular material interspersed with coarse osmiophilic granules and contains one closely applied membrane on the outermost surface. Several raised lenticular areas are seen on the coarse outer surface of the inner layer. These layers are 102 (75–128) and 176 (135–204) nm thick, respectively.
The sporocyst wall is thin, consisting of 3 to 4 unit membranes, and measures 27 (18–34) nm thick.  相似文献   

15.
Soil heat flux is one of the important components of surface energy balance. In this study, long-term estimation of soil heat flux from single layer soil temperature was carried out by the traditional sinusoidal analytical method and the half-order time derivative method of Wang and Bras [Wang and Bras (1999) J Hydrol 216:214–226]. In order to understand the characteristics of soil heat flux and to examine the performances of the two methods, a field experiment was conducted at a temperate and humid grassland in Cork, Ireland. Our results show that the soil heat flux had the same magnitude as the sensible heat flux at this grassland site. It was also demonstrated that the analytical method did not predict the soil heat flux well because the sinusoidal assumption for the temporal variation in soil heat flux was invalid. In contrast, good agreement was found between the soil heat flux measurements and predictions made by the half-order time derivative method. This success suggests that this method could be used to estimate soil heat flux from long-term remotely sensed surface temperature.  相似文献   

16.
Seed coat development of Harpagophytum procumbens (Devil's Claw) and the possible role of the mature seed coat in seed dormancy were studied by light microscopy (LM), transmission electron microscopy (TEM) and environmental scanning electron microscopy (ESEM). Very young ovules of H. procumbens have a single thick integument consisting of densely packed thin-walled parenchyma cells that are uniform in shape and size. During later developmental stages the parenchyma cells differentiate into 4 different zones. Zone 1 is the multi-layered inner epidermis of the single integument that eventually develops into a tough impenetrable covering that tightly encloses the embryo. The inner epidermis is delineated on the inside by a few layers of collapsed remnant endosperm cell wall layers and on the outside by remnant cell wall layers of zone 2, also called the middle layer. Together with the inner epidermis these remnant cell wall layers from collapsed cells may contribute towards seed coat impermeability. Zone 2 underneath the inner epidermis consists of large thin-walled parenchyma cells. Zone 3 is the sub-epidermal layers underneath the outer epidermis referred to as a hypodermis and zone 4 is the single outer seed coat epidermal layer. Both zones 3 and 4 develop unusual secondary wall thickenings. The primary cell walls of the outer epidermis and hypodermis disintegrated during the final stages of seed maturation, leaving only a scaffold of these secondary cell wall thickenings. In the mature seed coat the outer fibrillar seed coat consists of the outer epidermis and hypodermis and separates easily to reveal the dense, smooth inner epidermis of the seed coat. Outer epidermal and hypodermal wall thickenings develop over primary pit fields and arise from the deposition of secondary cell wall material in the form of alternative electron dense and electron lucent layers. ESEM studies showed that the outer epidermal and hypodermal seed coat layers are exceptionally hygroscopic. At 100% relative humidity within the ESEM chamber, drops of water readily condense on the seed surface and react in various ways with the seed coat components, resulting in the swelling and expansion of the wall thickenings. The flexible fibrous outer seed coat epidermis and hypodermis may enhance soil seed contact and retention of water, while the inner seed coat epidermis maintains structural and perhaps chemical seed dormancy due to the possible presence of inhibitors.  相似文献   

17.
The ultrastructural detail of spore development in Scutellospora heterogama is described. Although the main ontogenetic events are similar to those described from light microscopy, the complexity of wall layering is greater when examined at an ultrastructural level. The basic concept of a rigid spore wall enclosing two inner, flexible walls still holds true, but there are additional zones within these three walls distinguishable using electron microscopy, including an inner layer that is involved in the formation of the germination shield. The spore wall has three layers rather than the two reported previously. An outer, thin ornamented layer and an inner, thicker layer are both derived from the hyphal wall and present at all stages of development. These layers differentiate into the outer spore layer visible at the light microscope level. A third inner layer unique to the spore develops during spore swelling and rapidly expands before contracting back to form the second wall layer visible by light microscopy. The two inner flexible walls also are more complex than light microscopy suggests. The close association with the inner flexible walls with germination shield formation consolidates the preferred use of the term ‘germinal walls’ for these structures. A thin electron-dense layer separates the two germinal walls and is the region in which the germination shield forms. The inner germinal wall develops at least two sub-layers, one of which has an appearance similar to that of the expanding layer of the outer spore wall. An electron-dense layer is formed on the inner surface of the inner germinal wall as the germination shield develops, and this forms the wall surrounding the germination shield as well as the germination tube. At maturity, the outer germinal wall develops a thin, striate layer within its substructure.  相似文献   

18.
在不利的环境条件下,枝角类中有一部分种类可以形成卵鞍(ephippium),内含休眠卵。本文应用扫描电镜和透射电镜对隆线溞的卵鞍进行了超微结构的研究。研究表明:卵鞍外面大部分略呈浅的蜂窝状,内面则排布着多数卵石状小突起。卵鞍分为内外两层,两层的超微结构截然不同;各层又可分为三小层。  相似文献   

19.
Oocysts and sporocysts of Eimeria funduli sp. n. are described from the Gulf killifish, Fundulus grandis, on the basis of light microscopy, transmission and scanning electron miscroscopy, and location in the liver of infected hosts. The spherical sporulated oocysts of E. funduli isolated from liver tissue measure 20-31 (25) micrometer across with ovoid sporocysts 9-11 X 5-7 (10 X 6) micrometer. A micropyle, polar granule, and oocyst residuum are absent, but sporocysts have Stieda and substieda bodies, a few residual granules, and 10-25 (15) unique projecting structures with expanded distal portions that we term "sporopodia". Sporopodia 1-3 (2) micrometer high support a transparent membrane that completely surrounds the sporocyst. Sporozoites have one large posterior refractile body. Ultrastructurally, the oocyst wall consists of two thin layers of granular material: an electron-dense outer layer with a rough external surface and an electron-lucent inner one of approximately equal thickness. One or two unit membranes line the inner surface of the inner layer. Each layer is 40-60 (55) nm thick. The sporocyst wall, 78-130 (110) nm thick, consists of an electron-lucent material with the outer surface being more electron dense and giving rise to osmiophilic sporopodia; closely associated with these and the outer surface are one or two unit membranes. A thin osmiophilic layer of fine granular material lines the inner surface.  相似文献   

20.
The roles of secretory glands during the developmental process from an immature cercaria to a metacercaria in Cercaria shikokuensis were studied. Four types of secretory cells were identified in this species. On maturation of the cercaria in redia, the products of ventral gland cells and mucoid gland cells formed a thick surface coat on the mature cercaria, and the products of cephalic gland cells also formed a thin cover on the surface coat. In the process leading to the formation of a metacercaria, the surface coat constituted the outer layer of the cyst, mucoid gland cells secreted mucous substances inside the wall, and then cystogenous gland cells discharged their products to the inner wall. The cyst wall was composed of four layers, and it was thought that the outermost surface layer helped the cyst wall to adhere to the matrix and the intermediate layers helped to put together outer and inner walls.  相似文献   

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