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1.
文蛤花纹的形态及形成观察   总被引:3,自引:0,他引:3  
通过研究辽宁、山东、浙江、江苏和广西沿海的文蛤(Meretrix meretrix)壳的颜色及花纹特征,发现这些地区的文蛤可以分为2种类型,即花纹明显型和不明显型.辽宁和山东海域的文蛤贝壳表面具有花纹,只有极少数文蛤个体贝壳表面没有花纹;其中1龄个体贝壳表面都具有花纹.江苏地区的文蛤群体中,绝大多数个体的贝壳表面没有花纹,仅有极少数个体贝壳表面具有花纹.浙江地区的文蛤外表与山东文蛤很相似.广西地区的文蛤绝大部分没有花纹分布.外套膜组织装片确定了文蛤外套膜中的黄色素带与贝壳的色泽及花纹有关.黑色素带则与文蛤的生长状态有关,生长速度快的文蛤黑色素带浓而宽.所以,随着文蛤年龄的增长,黑色素带的颜色逐渐减弱直至消失.  相似文献   

2.
The rare-earth element (REE) contents of water and vegetables from two typical REE-high background regions and a normal region in Gannan, Jiangxi Province, indicated that the REE contents were significantly different from those of water and vegetables, respectively. The average values are 0.03 mg/L and 0.11 mg/L REE for water from regions A and B. As the REE contents of vegetables from region A are different from region B, it is suggested that there are a number of factors controlling the REE distribution from those among plants. By comparing with the normal region, the soluble REE contents of water from the REE-high background regions are higher than those of the normal region by factors of 18 and 68, respectively. The REE contents of most plants and crops from regions A and B are higher than those of the normal region. It is clear that the REEs are the indispensable elements of plants during their growing period. Why are the REE contents of some plants from regions A and B usually higher than those from the normal region? The answer is that the plants and crops have passively absorbed REE during their growth.  相似文献   

3.
4.
本文通过具体的形态比较指出,禄丰腊玛古猿和西瓦古猿应为同一类型的雌雄个体,它们与现代猩猩比较相似,而与大猩猩和黑猩猩差别较大,因此,它们可看作是猩猩的祖先。猩猩这一支大约是在一千二百万年前开始从人猿超科的进化主干上分化出来的。  相似文献   

5.
Abstract The tribe Plectrothripini is redefined with examination of its systematic relationships. Keys are provided to the ten genera and forty-seven species in this tribe; one genus and eighteen species are newly described; one genus and two species are newly synonymized; two genera, Chiridothrips and Eurytrichothrips , are here removed from this tribe. The species of the tribe occur throughout the tropical and subtropical regions of the world; seventeen species are recorded from the Oriental Region, seventeen species from the Neotropical Region, ten species from the Afrotropical Region, two from Australia and one from the Pacific. They seem to be fungus-feeders, being found mainly under the bark of trees or on dead branches.  相似文献   

6.
中国三叠纪鱼类综述   总被引:5,自引:1,他引:5  
三叠纪鱼类在中国分布广泛。与当时“南海北陆”的古地理格局一致,淡水鱼类主要分布于北方大陆的河湖相盆地,但也见于扬子板块与北方大陆碰撞后的四川盆地;海生鱼类则主要分布于华南和喜马拉雅地区。值得注意的是,鄂尔多斯盆地已知的三叠纪鱼类中,多数为海生类型或与海生鱼类密切相关。中国的淡水三叠纪鱼群主要由原始辐鳍鱼类组成,它们与西伯利亚和中亚的鱼群最为相近,但也有与劳业大陆其他地区及冈瓦纳大陆的鱼类相似的属种。海生鱼群则以“亚全骨鱼类”为主,并包含鲱亚部的进步类群和真骨鱼类的基干类型。华南扬子区拉丁至卡尼早期的鱼群远较早三叠世的鱼群丰富,且这一时期的鱼群与西特提斯同期的鱼群关系已极为密切,约有1/3的种类可归入相同的属。华南中下扬子区很可能是部分后来繁盛于特提斯区的三叠纪鱼类的发源地,如龙鱼类。中国的三叠纪鱼类虽然十分丰富,但大多已知鱼类仅限于零星发现和初步报道,因而仍有待全面深入的调查研究。  相似文献   

7.
The Z disk ultrastructure of white, intermediate, and red fibers from mammalian muscle is examined. Three models are proposed that explain the differences between the three types of Z disk. The three models are all based on the same concept, i.e., looping filaments from both sides of the Z disk. The differences between the models are in terms of the spatial relationships of adjacent loops within the Z disk. In the white fiber Z disk model all the loops from one side of the Z disk are on the same plane. In intermediate fibers there are two planes of loops from both sides of the Z disk, whereas in red fibers there are three planes of loops from both sides. The implications of these three structures are discussed in relation to known physiological differences between the fiber types.  相似文献   

8.
Evaluation of Holocene pollen records from the Romanian Plain   总被引:1,自引:0,他引:1  
This study is a critical review of pollen analyses carried out on Holocene sequences from 15 sites in and near the Romanian Plain. Three sites come from natural sediments, 10 sites are from anthropogenic deposits and two are from both anthropogenic and natural settings. The general reconstruction is of a steppe-forest-steppe vegetation through the Holocene. The nature of the deposits, however, casts doubts on this reconstruction. Deposits of archaeological sites generally yield pollen spectra that are influenced by human activities and thus unsuitable for vegetation reconstructions. Loess deposits are also unfavorable for pollen preservation because of high pH and porosity. Consequently, pollen spectra from loess deposits are strongly biased by selective pollen destruction. Research and experiments carried out by several authors suggest that spectra dominated by Asteraceae, Poaceae, Chenopodiaceae or Pinus pollen in soils and loess are a result of selective pollen destruction, especially if low pollen concentrations, progressive pollen deterioration or high frequencies of deteriorated or unidentifiable pollen are evidenced. The fact that pollen records from the Romanian Plain come from loess, alkaline peat or archaeological sites reduces their reliability for reconstructions of vegetation. The vegetation history of similar regions in Hungary, Bulgaria and Turkey suggests that early Holocene steppe vegetation was gradually replaced by forest or forest-steppe vegetation in the late Holocene. Records from lake sediments are required to find out whether the Holocene vegetation history of the Romanian Plain was similar.  相似文献   

9.
Abstract The Neotropical species of Drapetis Meigen are reviewed, and eight new species are described: alimacula , from Trinidad; atrinervalis , from Bahamas; naevia , from El Salvador; onconeura , from Costa Rica; steyskali , from Mexico; stictica , from Jamaica; tibialis , from Panama; and tuberculata , from Costa Rica. A lectotype is designated for Drapetis divergens Loew; Drapetis intermedia Smith is newly synonymized with divergens Loew. Two new species groups are described, the divergens group and the naica group. Two keys are provided: one distinguishing the Neotropical species of Drapetis ; the other distinguishing Drapetis Meigen, Crossopalpus Bigot and Elaphropeza Macquart. Drapetis flavicornis Melander, inermis Melander and zonalis Curran are assigned to Elaphropeza Macquart, new combinations, and redescribed. The heretofore unknown male of Elaphropeza flavicornis is described.  相似文献   

10.
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   

11.
The anomuran crabs are among the best known crustacean groups from the Pacific coast. However, this group is poorly known from the Caribbean coast of Costa Rica. In this compilation based on the literature and the collection at the Zoology Museum, Biology School, University of Costa Rica, we report the presence of 114 species of the Infraorder Anomura for Costa Rica, 20 species from the Caribbean, 96 species from the Pacific (two are present on both coasts). Twenty-nine species are new reports for Costa Rica, 15 from the Caribbean coast (74% of the total of species from that coast) and 14 from the Pacific (15% of the total from the Pacific). The range often species is extended to Costa Rica, siete from the Caribbean and three from the Pacific. Six species are reported for the first time from Cocos Island, where there are also four endemic species.  相似文献   

12.
Methods are described for the radiolabeling and determination of NAD+, poly(ADP-ribose), and protein-bound monomers of ADP-ribose in cultured mammalian cells. The adenine nucleotide pools of confluent monolayer cell cultures are radiolabeled using high-specific-activity [3H]adenine. Following any desired experimental manipulation, cultures are treated with trichloroacetic acid. Radiolabel in NAD+ can be rapidly determined from the acid-soluble fraction using dihydroxyboronyl Sepharose (DHB-Sepharose). The acid-insoluble material can be analyzed for radiolabeled polymers of ADP-ribose and protein-bound monomers of ADP-ribose. Polymers are separated from interfering material using dihydroxyboronyl-Bio-Rex 70 (DHB-Bio-Rex). Protein-bound monomers are separated from noncovalently bound ADP-ribose and different classes of (ADP-ribosyl) protein linkages are released by specific chemical treatments. The released ADP-ribose is then separated from interfering materials using DHB-Bio-Rex and DHB-Sepharose. Control experiments have demonstrated the sensitivity, selectivity, and precision of the methods. Major advantages of the methods are that they allow many simultaneous determinations and all components can be determined from material derived from a single dish of cultured cells. The methods should prove useful for detailed studies of the metabolism of both protein-bound monomers and polymers of ADP-ribose in cultured mammalian cells.  相似文献   

13.
The patterns of initiation and early development of the minor and major veins in the flat portion of the leaf blade of maize (Zea mays L.) follow similar patterns. The veins and their associated bundle sheath cells commonly arise from cell assemblages derived from a single cell lineage, or longitudinal file of cells, rather than from two “half vein units” derived from different cell lineages. In addition, apparently, none of the vascular cells derived from the procambium is directly related ontogenetically to a bundle sheath cell. In veins derived from larger cell assemblages, the lateral bundle sheath cells are more closely related ontogenetically to the mesophyll cells, which are derived from the ground meristem, than to the vascular cells, which are derived from procambium. The bundle sheath cells, accordingly, are interpreted as being ground meristem in origin.  相似文献   

14.
The status of all of the putative member genera of the subfamily Aephnidiogeninae is reconsidered, based mainly on the morphology of the terminal genitalia. Aephnidiogenes Nicoll, 1915 is the only genus retained in the Aephnidiogeninae. Aephnidiogenes major Yamaguti, 1934 from Diagramma labiosum from the southern Great Barrier Reef is redescribed with particular reference to the terminal genitalia, and is shown to lack a true cirrus-sac, a condition considered to be diagnostic of the Aephnidiogeninae. Holorchis Stossich, 1901 is placed in the subfamily Lepidapedinae. Holorchis pycnoporus Stossich, 1901 from Pagellus acarne from off Spanish Sahara and from Diplodus vulgaris from off Italy and H. legendrei Dollfus, 1946 from Sparodon durbanensis and D. sargus from off eastern Cape Province, South Africa and from Pagellus erythrinus from the Adriatic Sea and Italy are studied and illustrated. The terminal genitalia of H. pycnoporus are found to be enigmatic, but those of H. legendrei are found to fit clearly into the 'Lepidapedon-like' pattern. A new genus Austroholorchis is erected in the Lepidapedinae, with A.sprenti (Gibson, 1987) n. comb. as the type-species. Its diagnostic features are its ani, infundibuliform oral sucker and the position of the ovary at about mid-level of the uterus . A. sprenti is illustrated, its hosts in Queensland waters being Sillago maculata, S. analis and S. ciliata. A. levis n. sp. is described from Sillago bassensis from south-western Western Australia. The genus PseudaephnidiogenesYamaguti, 1971 is placed in the Lepidapedinae. P. rhabdosargi (Prudhoe, 1956) from Rhabdosargus sarba from off Natal, South Africa is illustrated and the terminal genitalia of P. rhabdosargi from R. sarba and from R. holubi from off eastern Cape Province and Pseudaephnidiogenes rossi Bray, 1985 from Caffrogobius nudiceps from off eastern Cape Province, South Africa are illustrated. The genus Pseudoholorchis Yamaguti, 1958 is placed in the subfamily Lepocreadiinae. The terminal genitalia of P. pulcher (Manter, 1954) from Latridopsis ciliaris from New Zealand are illustrated. The genus Neolepocreadium Thomas, 1960 is placed in the Lepocreadiidae.  相似文献   

15.
作者在整理北美外来入侵植物中发现一些起源(或主要分布)于东亚植物的学名,在北美乃至欧洲使用非常混乱.本文特将有关重要类群整理出来,包括异名、原产地、北美的分布以及必要的讨论等.  相似文献   

16.
Eimeria leucuri is described from white-tailed ptarmigan (Lagopus leucurus), and E. oreoecetes from white-tailed ptarmigan and blue grouse (Dendragapus obscurus) from Colorado. Oocysts of E. leucuri are ellipsoidal, 26.6 by 17.7 micron, each bearing a micropyle, micropyle cap, up to 4 polar granules, but no oocyst residuum. The lemon-shaped sporocysts are 15.4 by 6.7 micron, and have Stieda bodies and large amounts of sporocyst residuum. The sporocyst contents are enclosed in a membrane. Oocysts of E. oreoecetes are subspherical, 26.0 by 22.6 micron, and have up to 4 polar granules. The lemon-shaped sporocysts are 14.6 by 8.8 micron, and have both Stieda bodies and substiedal bodies and a large amount of sporocyst residuum. The sporocyst contents are enclosed in a membrane. These are the first coccidia to be described from these tetraonids.  相似文献   

17.
广西和广东现代人的面颅特征   总被引:1,自引:1,他引:0  
根据22项的面颅测量数据与北方地区(西安、青岛)现代人相应项目作比较和分析,结果表明我国南北地区间的面颅特征的差异程度既有大部分项目的近似,又存在南方地区面颅的上面高、眶高与鼻高等的纵径上都较北方地区为低的显著差异。  相似文献   

18.
Fifty-two species of the Laboulbeniales are reported for the first time from Bulgaria. One new species of Diphymyces, parasitic on Hexaurus schipkaensis is also described. The total number of species from Bulgaria is thus raised from 15 to 68. The first records of any of the Laboulbeniales are reported from Armenia, Eritrea, Georgia and Kazakhstan; more new records are reported also from Albania, China, Cyprus, Hungary, Italy, Mongolia, Namibia, Romania, Slovenia, Switzerland, United Kingdom and Yemen. The antheridia of Misgomyces dyschirii are described and illustrated.  相似文献   

19.
The position of the Haplotaxidae in the evolution of oligochaete annelids   总被引:4,自引:4,他引:0  
The Haplotaxidae have all the characteristics to support the hypothesis that they are the living descendents of the stem forms from which all of the Oligochaeta Clitellata (Orders Lumbriculida, Haplotaxida, Lumbricida, Tubificida) can be derived. The Aphanoneura are distinct from the Clitellata and are raised to a separate Class. There is no evidence to support the view that the elaborate setae of many Tubificida are derived from a polychaete ancestry; both are held to be independent modifications to aquatic life derived from a simple burrowing protoannelid with lumbricine setae.  相似文献   

20.
五种胡椒属来源的海风藤挥发油成分的比较研究   总被引:7,自引:0,他引:7  
本文对四种及一变种胡椒属植物的茎叶进行了挥发油的GC比较。并以GC-MS研究了毛Piper puberulum(Benth.)Maxim.的挥发油成分,共鉴定了54个化合物,其中主要成分为倍半萜。结果表明,毛的挥发油成分与其它四种样品差异很大。  相似文献   

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