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Upper limb reduction was diagnosed by ultrasound scan at 17 weeks after chorion villus sampling at 9 weeks' gestation. Pregnancy was terminated and necropsy confirmed limb reduction in an otherwise normal fetus. The relationship of limb reduction to amniotic band syndrome is discussed. 相似文献
414.
M. Blunck W. -D. Busse G. Meister E. Möller A. Mullen L. A. A. van Rooijen 《Die Naturwissenschaften》1989,76(3):96-98
Online searching in publically available patent files opens up interesting possibilities to provide a rapid response to critical questions. A computerized analysis of all patents of leading German pharmaceutical companies over the last decade in important indication areas is described. Supported by subsequent manual processing of individual patents it is shown that duplicate experiments on animals practically never occur. 相似文献
415.
416.
Consensus on the evolutionary position of turtles within the amniote phylogeny has eluded evolutionary biologists for more than a century. This phylogenetic problem has remained unsolved partly because turtles have such a unique morphology that only few characters can be used to link them with any other group of amniotes. Among the many alternative hypotheses that have been postulated to explain the origin and phylogenetic relationships of turtles, a general agreement among paleontologists emerged in favoring the placement of turtles as the only living survivors of the anapsid reptiles (those that lack temporal fenestrae in the skull). However, recent morphological and molecular studies have radically changed our view of amniote phylogenetic relationships, and evidence is accumulating that supports the diapsid affinities of turtles. Molecular studies favor archosaurs (crocodiles and birds) as the living sister group of turtles, whereas morphological studies support lepidosaurs (tuatara, lizards, and snakes) as the closest living relatives of turtles. Accepting these hypotheses implies that turtles cannot be viewed any longer as primitive reptiles, and that they might have lost the temporal holes in the skull secondarily rather than never having had them. 相似文献
417.
This study investigated the influence of cat urine odour in suppressing development and fertility in Campbell's hamster males.
Exposure to this odour from postnatal day 11 until day 45 (sexual maturation) resulted in reduced sex organ weights, reduced
testosterone levels and in an increase in abnormalities of the synaptonemal complex in both sex chromosomes and autosomes.
Subsequent breeding experiments revealed a significant decrease in litter size. All these data indicate a severe effect of
predator odour on the breeding success of potential prey species. It is assumed that these effects are caused by the sulphurous
compounds in the urine; however, the underlying mechanisms are not yet known.
Received: 31 January 2000 / Accepted in revised form: 6 June 2000 相似文献
418.
The Australian buprestid beetle Merimna atrata (Coleoptera: Buprestidae) approaches forest fires because its larvae develop in freshly burnt wood. So far nothing is known
about possible sensory systems enabling the beetles to detect fires and to cope with the thermal environment close to the
flames. We found that M. atrata has two pairs of infrared (IR) organs on the ventrolateral sides of the abdomen. Each IR organ consists of a specialized
IR-absorbing area which is innervated by one thermosensitive multipolar neuron. The primary dendritic branches ramify into
more than 800 closely packed terminal endings which contain a large number of mitochondria. We called the special morphology
of the dendritic region a terminal dendritic mass. The type of IR receptor found in M. atrata is unique in insects and can best be compared with the IR organs of boid snakes.
Received: 14 August 2000 / Accepted in revised form: 18 October 2000 相似文献
419.
Laperdina T. G. Melnikova M. V. Koval A. T. Sidorov Y. F. Nagorny V. A. Ostapchuk V. I. 《环境科学学报(英文版)》2000,(Z1)
IntroductionSiberiaandtheFarEastaretheoldestandtherichestgold miningareasofRussia .Intensivegold miningherestartedinthebeginningofthe 19thcentury(Vyazelshchikov ,1963) .Forthemostpartgold bearingoresandsandswereprocessedwiththeuseofamalgamationmethodforgolde… 相似文献
420.