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1.
东北地区蒙古栎群落区系成分   总被引:5,自引:0,他引:5  
根据吴征镒、王荷生区系分析方法, 分析了东北地区蒙古栎群落中261 种维管植物的区系成分, 其中温带成分占47-47 % , 东亚成分占42-02 % , 中国特有成分占10-51 % ( 世界分布不统计在内) 。并分析了种所在属的分布区类型, 温带分布属占90-3% 。还分别分析了蒙古栎群落的乔木层、灌木层、草本层以及层间植物的区系成分。  相似文献   

2.
记述了产自四川省自贡市的一具蜥脚类幼年个体材料。根据枢椎极短而高,颈神经棘低、上缘平直、前后延长,背神经棘呈横宽的板状,中部颈肋的前突分叉等特征将它命名为一新属新种——张氏大安龙Daanosaurus zhangi gen.etsp.nov.,并将它归入巧龙亚科Bellusaurinae。  相似文献   

3.
采用同位素示踪和肠道离体灌流方法,研究了草鱼离体肠道对亮氨酸(Leu)、酪氨酸(Tyr)的吸收转运与利用。实验结果表明:当Leu浓度从1.0mmol/L增加到5.0mmol/L、10mmol/L时,肠道吸收转运的速度表现出“高浓度抑制”效应,运输到肠道外的比例为83%、66%和35%;合成肠道蛋白质的比例为2%、5%和13%;肠道组织内游离形式的比例为9%、28%和49%;其他形式的比例为6%、1%和3%。Tyr浓度从0.5mmol/L增加到1.5mmol/L、2.5mmol/L时,肠道对Tyr的吸收转运速度也随之增加,运输到肠道外的比例为52%、55%和55%;合成肠道蛋白质的比例为17%、15%和16%:肠道组织内游离形式的比例为7%、10%和16%;其他形式的比例为24%、20%和13%。肠道在吸收转运Leu和Tyr的同时,也利用它们合成蛋白质的和其他方面,Leu的吸收利用受灌流试验氨基酸浓度影响较大、而Tyr受影响较小;随着肠道内灌流的试验氨基酸浓度增加,吸收转运到肠道外的比例下降、留存于肠道内的比例增加,肠道合成的蛋白质绝对量也增加。    相似文献   

4.
5.
中国大蒜芥属(十字花科)叶表皮微形态学研究   总被引:1,自引:0,他引:1  
利用光学显微镜观察了中国十字花科大蒜芥属9种1变种植物的叶表皮形态。结果表明:中国大蒜芥属植物叶上表皮细胞通常为多边形,垂周壁平直或弓形,少有稍浅波状,叶下表皮细胞为不规则形,垂周壁波状或深波状;气孔器类型均以不等细胞型为主,少有无规则型,偶有平列型。依据叶表皮特征,可将中国大蒜芥属划分为三种类型: (1)叶上表皮无气孔分布或偶见; (2)叶上表皮气孔常明显几个聚成一簇或排成短列,气孔密度小于叶下表皮; (3)叶上表皮气孔比较均匀分布,气孔密度与叶下表皮近相似。  相似文献   

6.
本文通过禄丰腊玛古猿和西瓦古猿的下颌骨与现代大猿类和其它同时代的古猿及南方古猿类的下颌骨的比较得出:禄丰的两类古猿有不少特征与猩猩相似,因此它们可能与猩猩有较密切的关系,两类古猿可能是同一类型的雌雄个体。但另一方面,禄丰腊玛古猿又显示出一些与南方古猿相似的性状,因而另一种可能是腊玛古猿是与西瓦古猿不同的类型,它比西瓦古猿更接近于人猿的共同主干。  相似文献   

7.
M A Qayyum  M A Beg 《Acta anatomica》1975,93(4):554-567
The anatomy and neurohistology of the tongue of the Indian goat, Capra aegagrus, have been described. The apex linguae is notched in the centre. The foramen caecum is found to be absent. The sublingua could not be traced. The filiform papillae are the most common and divided into three types: the simple, giant, and true filiform papillae. The true filiform papillae are the most developed of the three types. The foliate papillae are absent. There are 13--14 circumvallate papillae arranged in two rows in a V-shaped pattern. The fungiform papillae are large and could easily be seen with the naked eye. They are scattered over the entire dorsum, being in abundance at the tip. The tongue of the goat is richly innervated. On the dorsum, the lamina propria is innervated by thick nerve fibres. In the fungiform papillae quite a large number of nerve fibres could be seen. The circumvallate papillae are also abundantly provided with nerves. A few ganglion cells are found below the circumvallate papillae. Thick nerve fibres are seen across the numerous glands and their ducts. Muscle fibres and connective tissue are also richly innervated.  相似文献   

8.
All species that have been described of the genera mentioned in the title are listed and their systematic position given. The species of Stilifer (with 11 species, including S. inflatus sp.n. and 5. concavus sp.n.) are parasites of starfishes. Scalenostoma (3 species) are parasites of stone corals. Thyca (with 8 species) is removed from Capulidae, and included in Eulimidae. T. hawaiiensis sp.n. is described. The species of Thyca are parasites of starfishes. The species of Mucronalia (including M. trilineata sp.n.) are probably parasites of ophiuroids and Echineulima (with 4–6 species, including E. ponderi sp.n.) are parasites of echinoids. All species are figured, their characteristics are given and their host species and distributions are listed. Keys are given to the species of each genus, except Mucronalia. The genera Stilimella Laseron and Hyperlia Pilsbry are synonymized with Scalenostoma and the genera Kiramodulus Kuroda, Granulithyca Habe and Bessomia Berry are considered subgenera of Thyca.  相似文献   

9.
Petter Portin 《Genetics》1975,81(1):121-133
The mutations of the Abruptex locus in Drosophila melanogaster fall into three categories. There are recessive lethal alleles and viable alleles. The latter can be divided into suppressors and nonsuppressors of Notch mutations. The recessive lethals are lethal in heterozygous combination with Notch. As a rule the recessive lethals are lethal also in heterozygous combination with the viable alleles. Heterozygous combinations of certain viable alleles are also lethal. In such heterozygotes, one heteroallele is a suppressor of Notch and the other is a nonsuppressor. Other heterozygous combinations of viable alleles are viable and have an Abruptex phenotype. The insertion of the wild allele of the Abruptex locus as an extra dose (carried by a duplication) into the chromosomal complement of the fly fully restores the viability of the otherwise lethal heterozygotes if two viable alleles are involved. The extra wild allele also restores the viability of heterozygotes in which a lethal and a suppressor allele are present. If, however, a lethal and a nonsuppressor are involved, the wild allele only partly restores the viability, and the effect of the wild allele is weakest if two lethal alleles are involved. It seems likely that of the viable alleles the suppressors of Notch are hypermorphic and the nonsuppressors are hypomorphic. The lethal alleles share properties of both types, and are possibly antimorphic mutations. It is suggested that the locus is responsible for a single function which, however, consists of two components. The hypermorphic mutations are defects of the one component and the hypomorphic mutations of the other. In heterozygotes their cumulative action leads to decreased viability. The lethal alleles are supposed to be defects of the function as a whole. The function controlled by the locus might be a regulative function.  相似文献   

10.
Lipid-cholesterol interactions. Monte Carlo simulations and theory.   总被引:5,自引:5,他引:0       下载免费PDF全文
Results of Monte Carlo calculations of order parameter profiles of lipid chains interacting with cholesterol are presented. Cholesterol concentrations in the simulations are sufficiently large that it is possible to analyze profiles for chains which are near neighbors of two or more cholesterol molecules, chains which are neighbors to a single cholesterol, and chains which are not near any cholesterol molecules. The profiles, show that cholesterol acts to significantly decrease the ability of neighboring chains to undergo trans-gauche isomeric rotations, although these chains are not all forced into all-trans conformations. The effect is significantly greater for chains which are neighbors to more than one cholesterol. The Monte Carlo results are next used as a guide to develop a theoretical model for lipid-cholesterol mixtures. The properties of this model and the phase diagram which it predicts are described. The phase diagram is then compared with experimentally determined phase diagrams. The model calculations and the computer simulations upon which they are based yield a molecular mechanism for several of the observed phases exhibited by lipid-cholesterol mixtures. The theoretical model predicts that at low temperatures the system should exhibit solid phase immiscibility.  相似文献   

11.
《Anthrozo?s》2013,26(2):72-80
ABSTRACT

Results from several studies in The Bahamas, which included 511 interviews with residents and data on 776 dogs, are reported. The composition and characteristics of the dog population are described. The majority of dogs, both owned and unowned, are local mongrels called “potcakes.” The median age of the dog population is three years. Potcakes are given a lower level of health care than dogs considered to resemble a recognised breed. Many dogs have no place in the household and are able to roam. The dynamics of the owned and unowned dog populations are derived, and abandoned dogs are shown to sustain the free-roaming population. The free-roaming dog population breeds throughout the year but it has a breeding cycle longer than six months, which is probably caused by its ill health. Despite the nuisance caused by unowned dogs, residents are tolerant towards them, and over half the households feed dogs they do not own. The changes in pet ownership required to increase the welfare of dogs are discussed.  相似文献   

12.
目的研究及观察SD大鼠和巴马小型猪皮肤的正常比较组织学。方法取SD大鼠和巴马小型猪不同部位的皮肤进行石蜡切片、HE染色,光学显微镜观察。结果两种动物的皮肤组织学结构在以下方面存在着显著差异:1.SD大鼠的毛囊成簇分布,平均3~9成群,而巴马小型猪的毛囊较稀少;2.SD大鼠表皮较薄,没有透明层,基底细胞缺乏异质性,真皮与表皮连接面平坦,没有皮钉;而在巴马小型猪皮肤表皮和真皮连接区,有上下交错的表皮皮钉和真皮乳头;3.SD大鼠的真皮结构相对松散,真皮血管系统不发达,而巴马小型猪皮肤的真皮网织层和乳头层交界的地方,水平分布着很多的浅表小静脉和小动脉丛,这种血管分布的方式与人类皮肤中的血管分布极为类似;4.SD大鼠的汗腺只局限于足垫的皮肤,汗腺上皮只有一种细胞类型,腺细胞呈立方形或矮柱状,胞核圆形,导管短而弯曲,由两层上皮细胞组成。而巴马小型猪皮肤的汗腺是顶泌汗腺,分布于真皮和脂肪相接的真皮深层,分泌部为粗管,管腔大,盘曲成团。腺细胞呈立方形或扁平,胞核圆形或长梭形。腺细胞与基膜之间也有肌上皮细胞。导管较细而直,开口于毛囊上段。  相似文献   

13.
The main stages and ways of development of insect biogeography in Russia are discussed. Three general research programs (studies of ranges, zones, and regions) are described. The role of the regional approach in biogeography is characterized. Some problems related to studies of insect ranges are evaluated, and the need for creating practical range maps is emphasized. The relationships between the insect distribution patterns and the life zones are discussed. The specific features of zonation in insect biogeography are noted. Special attention is paid to establishing the zones with unified population distribution patterns within a species range. The role of geozoological investigations and opportunities of modern information technologies are characterized relative to evaluation of general patterns of insect assemblage distribution. The problems of regionalization in insect biogeography are discussed. Three main approaches (intuitive, a priori, and a posteriori) are determined. Some advantages of using population and assemblage distribution patterns in regionalization are emphasized. The role and possibilities of insect biogeography studies for in the field of reconstruction of past and long-term forecasting are characterized.  相似文献   

14.
Essential background on the determination of absolute configuration by way of single-crystal X-ray diffraction (XRD) is presented. The use and limitations of an internal chiral reference are described. The physical model underlying the Flack parameter is explained. Absolute structure and absolute configuration are defined and their similarities and differences are highlighted. The necessary conditions on the Flack parameter for satisfactory absolute-structure determination are detailed. The symmetry and purity conditions for absolute-configuration determination are discussed. The physical basis of resonant scattering is briefly presented and the insights obtained from a complete derivation of a Bijvoet intensity ratio by way of the mean-square Friedel difference are exposed. The requirements on least-squares refinement are emphasized. The topics of right-handed axes, XRD intensity measurement, software, crystal-structure evaluation, errors in crystal structures, and compatibility of data in their relation to absolute-configuration determination are described. Characterization of the compounds and crystals by the physicochemical measurement of optical rotation, CD spectra, and enantioselective chromatography are presented. Some simple and some complex examples of absolute-configuration determination using combined XRD and CD measurements, using XRD and enantioselective chromatography, and in multiply-twinned crystals clarify the technique. The review concludes with comments on absolute-configuration determination from light-atom structures.  相似文献   

15.
The results of computer simulations of the electron-optical system of an electron gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the electron beam formation and transport. The electron trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and transport are described. Recommendations for optimizing the electron-optical system with a plasma emitter are presented.  相似文献   

16.
17.
Summary The general ultrastructural features of the hypothalamo-neurohypophysial system in rats with hereditary hypothalamic diabetes insipidus (DI-rats, Brattleboro strain) are described. There is no decisively distinguishing difference between the neurons of the supraoptic and paraventricular nuclei. The neurons of both nuclei show signs of active protein synthesis. The perikarya of the neurons are markedly hypertrophic, the nuclei are large and the nucleoli prominent. In the cytoplasm there are numerous ribosomes, abundant rough-surfaced endoplasmic reticulum and extensive Golgi complexes. However, very few neurosecretory granules are to be seen. The axons of the hypothalamo-neurohypophysial tract are likewise enlarged and the paucity of neurosecretory granules is a striking feature also in the area of the tract. The majority of nerve endings in the posterior pituitary of DI-rats are devoid of neurosecretory granules. Microvesicles are abundant in the nerve endings and there are findings which suggest that microvesicles are involved either in endoor exocytosis. The signs of active protein synthesis and the concomitant paucity of neurosecretory granules are interpreted to imply transportation of the secretory proteins in an extragranular phase. The possible mode of release of the secretory proteins from the nerve endings and the role of microvesicles therein are discussed.This study has been supported by grants from the Finnish Cultural Foundation and the Sigrid Jusélius Foundation. The collaboration of Professors Antti Arstila and Tapani Vanha-Perttula is gratefully acknowledged.The Brattleboro-rats were kindly provided by Dr. Heinz Valtin, to whom we express our thanks.  相似文献   

18.
十八个产地兴安落叶松种皮微形态的研究   总被引:4,自引:0,他引:4  
乔辰  弓彩霞 《植物研究》1996,16(4):467-470
对18个不同产地的兴安落叶松种皮微形态进引扫描电镜观察。结果表明,种子背面均为条网状纹饰,腹面为拟脑状纹饰,种孔周围呈条带状皱波纹饰,种孔周围形态存在三种类型。种皮纹饰在种内基本上是稳定的,其中腹面纹饰较背面纹饰的变异幅度大。种皮纹饰特征可以作为兴安落叶松种子鉴定的依据之一。  相似文献   

19.
李寿建  汪琦  刘奇正  董彩虹 《菌物学报》2019,38(9):1395-1406
茯苓Wolfiporia cocos是我国药食两用的传统中药,本文对茯苓的分类地位、交配型、生活史、遗传育种、菌核栽培以及组学相关研究进展进行了总结,对有关专利进行了分析。以研究及生产现状为基础,分析了茯苓在基础生物学方面研究的不足、菌核栽培中存在的相关问题,重点分析了交配型研究、子实体诱导形成和生活史研究等重要方面,并对未来茯苓生物学研究和科学栽培进行了展望。  相似文献   

20.
This article analyzes costs and relative benefits of several hundred flexible manufacturing systems (FMSs) in the world. The analyses are based on the computerized data bases, which make it easy to correlate different cost and benefit indicators with each other and to look for regular patterns and tendencies in the applications. Both investment cost distributions and the system complexity distributions are analyzed. The relative benefits and advantages and their relationships are shown. Finally, technical and economic explanations for successful implementation strategies are given. The results show that there are two classes of economically successful systems. The small-scale and technically compact systems are usually used in small-batch production for the replacement of semimanual production. The main benefits are increased capacity and productivity as well as quality improvements. The large-scale and technically complex systems are used in large-volume production for the replacement of fixed automation and transfer lines. The benefits are mainly due to the increased potential for flexibility and capital savings.  相似文献   

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