首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   34篇
  免费   1篇
  2020年   1篇
  2017年   1篇
  2014年   1篇
  2013年   1篇
  2011年   2篇
  2009年   1篇
  2008年   1篇
  2006年   3篇
  2005年   2篇
  2004年   2篇
  2003年   1篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1997年   4篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1985年   1篇
  1981年   1篇
排序方式: 共有35条查询结果,搜索用时 15 毫秒
11.
本文记述了分布在山东省莒南县石泉水库附近淡水鱼苗培育池中的介甲目甲壳动物隐妇蚌虫属的一个新种——石泉隐妇蚌虫Caenestheria shiquanica sp.nov。并提供了新种的近似种川候隐妇蚌虫C.kawamurai(Uéno,1940)Hu,1988的主要形态区别特征之资料。  相似文献   
12.
Four branchiopod species occur on the Maltese Islands, viz. Branchipus schaefferi, B. visnyai, Cyzicus tetracerus and Triops cancriformis. All four live in freshwater pools, but it is noteworthy that, beside B. schaefferi, T. cancriformis was recorded from a mesohaline, coast-fringing habitat.  相似文献   
13.
Previously unknown minute ornamentation patterns of conchostracans are described based on SEM investigation of several collections from the terminal Permian volcanic deposits of the Tunguska Syneclise. Lioestheria (Lioestheriidae) shows ovally elongated cells arranged in rows along the growth bands, Mimoleaia (Leaiidae) has large polygonal cells with double walls, and Echinolimnaia (Echinolimnadiidae fam. nov.) displays a pattern with small polygonal cells bearing small spines along their walls. Diagnoses of genera and species are refined. New data about their distribution are presented.  相似文献   
14.
东方叶肢介(Eosestheria)是著名热河生物群中最为常见的一类甲壳动物,关于它的形态、壳瓣结构及微细纹饰特征的研究已相当详尽,但一直没有关于其软体构造的报道。本文描述的凌源东方叶肢介(Eosestheria lingyuanensis)采自辽宁北票市尖山沟村,产于下白垩统义县组的尖山沟夹层。这些软体构造包括:头部...  相似文献   
15.
叶肢介(Conchostraca)的系统发育问题一直是甲壳动物研究中颇具争议的一个课题.本研究测定了我国2种叶肢介(Eocyzicus mongolianus,Eoc yzicus orientalis)的28S rDNA D1-D2区基因序列和16S rDNA E-G区序列,并与GenBank中的20种叶肢介序列一起...  相似文献   
16.
Weeks  Stephen C.  Marcus  Vivien  Alvarez  Sheila 《Hydrobiologia》1997,359(1-3):191-197
Several life history measures (growth rate, egg production, molt frequency, age at maturity and lifespan) were measured on several clam shrimp hermaphrodites (Eulimnadia texana Packard) grown in a laboratory setting under optimal growth conditions. Growth rates were high early in life, and then dropped dramatically when egg production began (day 5–6). Early egg production was low, and increased until approximately day 7, after which production leveled off for several days. Reproductive senescence was noted after day 17, with clutch sizes continuously dropping until death. Average molts per day was approximately 1.1, and molting seemed to be more closely associated with egg production than with growth. Growth and egg production were negatively correlated, indicating a possible trade-off between these two traits. No other trade-offs were detected. These shrimp show typical early-colonist life history traits, displaying high initial growth, early reproduction at a high rate, and then early senescence and death. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
17.
The larval development of "conchostracans" has received only scattered attention. Here I present the results of a study on the larval (naupliar) development and the metamorphosis of Lynceus brachyurus, a member of the bivalved branchiopod order the Laevicaudata. Lynceus brachyurus is the only species of the "Conchostraca" in Denmark. The phylogenetic position of the Laevicaudata has traditionally been a source of controversy, and this study does not solve the question completely. This work focuses on features potentially important for phylogeny. The general appearance of the larvae of L. brachyurus has been known for more than a century and a half, and some of its unique features include a large, larval dorsal shield; a huge, plate-like labrum; and a pair of immovable, horn-like antennules. However, many details relating to limb morphology, potentially important for phylogeny, have not been studied previously. Based on size categories, five or six larval stages can be recognized. The larvae approximately double their length and width during development (length: 230-520 microm). Most morphological features stay largely unchanged during development, but the antennal coxal masticatory spines are significant exceptions: they become bifid after one of the first molts. In all larval stages only the antennae and the mandibles actively move. In late naupliar stages the trunk limbs become visible as rows of laterally placed, undeveloped, and still immovable lobes. Swimming is performed by the antennae, whereas the mandibles appear to be involved mainly in feeding, as in other branchiopod larvae. The last naupliar stage undergoes a small metamorphosis to the first juvenile stage, the details of which in part were studied by following the premolt juvenile condition through the cuticle of the last stage nauplius. Among other changes there is a characteristic change in the shape and morphology of the univalved dorsal naupliar shield to a bivalved juvenile carapace. The general morphologies of the antennae and the mandibles are very similar to those of other branchiopod larvae and fall well within the "branchiopod naupliar feeding apparatus" recognized as a branchiopod synapomorphy by Olesen (2003), but some specific features shared with the larvae of other "conchostracans" are also identified. These special "conchostracan" features include: 1) a similar antennular setation; 2) a similar comb-like setulation of the bifid antennal coxal processes; and 3) mandibular palpsetae with setules condensed. In light of recent suggestions concerning branchiopod phylogeny (Cyclestheria as a sister group to the Cladocera), these similarities probably do not support a monophyletic "Conchostraca" but rather are symplesiomorphies of this taxon. A final decision must await a phylogenetic analysis of a more complete set of characters.  相似文献   
18.
沈炎彬 《古生物学报》1994,33(2):156-164
描述了采自英国伯维克郡下石炭统下泥石群(杜内附)叶肢介一新属-longesheriagen.nov.据壳瓣生产带上发育大网状纹饰构造。归属于Loxomegaglyptidae科,从而使该科的地质历程从晚二叠世,一直追溯到早石炭世早期。讨论了新属与该科其它属之间的形态特征联系。认为化石为原理藏,含叶肢介崦层属非海相沉积。  相似文献   
19.
沈炎彬 《古生物学报》2006,45(2):175-181
报道的叶肢介新属(Kenyaestheria gen.nov.)采自肯尼亚Maji ya Chumvi地区的一钻孔,属下三叠统上马几牙楚姆维组(Upper Majiya Chumvi Formation),其特征为壳瓣后背缘最后几条生长线靠近背缘处形成一个凹缘构造,但生长线在背缘并不反转弯曲,同时具有放射线纹饰,据此将其归于凹缘叶肢介科(Ulugkemiidae)。该科是一个灭绝的类群,分布于中泥盆统至上三叠统,古生代的类型都发现于欧亚大陆,晚三叠世的Triasulugkemia见于阿根廷,新属首见于早三叠世,也是在南大陆出现的第二例凹缘叶肢介类。孢粉Lunatisporites pellucidus和叶肢介Aquilonoglypta—Cornia—Palaeolimnadia—Falsisca组合指示含化石的地层时代为早三叠世早期。  相似文献   
20.
新疆中二叠世叶肢介化石   总被引:2,自引:0,他引:2  
描述新疆阜康三工河剖面芦草沟组的叶肢介石2科3属4种(其中2新种)和鄯善照壁山剖面“照壁山组“的叶肢介化石2科4属5种,时代均为中二叠世。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号