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241.
Il'inskii E. N. Merzlyakov A. Yu. Vinnikov A. V. Vinnikov K. A. Buryak P. N. 《Russian Journal of Marine Biology》2004,30(1):65-69
Based on the data of two summer surveys carried out in 2002, the biomass of bottom fishes of the West Kamchata Shelf was assessed. The obtained results were considered within the series of similar annual assessments conducted since 1996. It was displayed that against the background of some increase in the total biomass of bottom fishes, the biomass of the plaices prevailing there, which had previously been the two dominating species had decreased. As a result of the quantitative variations that occurred, the present community structure differs considerably from that observed over the past twenty years. 相似文献
242.
Don Maurer George Robertson Thomas Gerlinger 《International Review of Hydrobiology》1994,79(4):591-603
Community structure of soft-bottom macrobenthos from Newport Submarine Canyon, California, was compared to that on the adjoining shelf. Four hypotheses involving sediment characteristics, community structure, benthic feeding types and seasonal population fluctuations were posed. Results indicated that there were statistically significant differences between the canyon and adjoining shelf. Although there were differences in sediment geochemistry between the canyon and shelf, sediment type played the major role influencing differences in community structure and feeding. Operation of a shelf outfall has not demonstrably changed the canyon soft-bottom macrobenthos for at least 16 years and probably closer to 27 years. 相似文献
243.
Toxicological tests on the present status of resistance to acaricides in six strains of the two‐spotted spider mite (Tetranychus urticae Koch) in New Zealand are reported. Resistance to parathion appears widespread; cross‐resistance to formetanate is developed. Resistance to Plictran has not developed, and there is no indication of high levels of Kelthane resistance. The levels of genetic incompatibility operating between the strains are also investigated. The causes of such incompatibilities and their possible exploitation in integrated control programmes are discussed. 相似文献
244.
T. D. Gibson J. N. Hulbert S. M. Parker
J. R. Woodward
I. J. Higgins
《Biosensors & bioelectronics》1992,7(10):701-708The storage stability of amperometric enzyme electrodes has been enhanced by a combination of a soluble, positively charged polymer, diethylaminoethyl (DEAE)-dextran, and a sugar alcohol, lactitol. Two different types of alcohol biosensor have been produced using the enzyme alcohol oxidase, isolated from the methylotrophic yeast Hansenula polymorpha. The first employs enzyme entrapment between two membranes with direct hydrogen peroxide amperometry at +0·65 V. The second was based on the mediated, coupled reaction with horseradish peroxidase and N-methyl phenazimiumtetracyanoquinonedimethane (NMP-TCNQ) on a graphite electrode. In both cases, addition of the stabilizers promoted a considerable increase in the storage stability of the enzyme component, as indicated by an increase in the shelf life of desiccated biosensors under conditions of thermal stress at 37°C. In addition, an L-glutamate biosensor constructed from NMP-TCNQ-modified graphite electrodes and L-glutamate oxidase also exhibited an increase in shelf life when stored, desiccated in the presence of stabilizers. 相似文献
245.
Douglas Brandon-Jones 《Biological journal of the Linnean Society. Linnean Society of London》1996,59(3):327-350
A reappraisal of the zoogeography and systematics of Asian colobines demonstrates marked discontinuities in their distribution. The Bornean proboscis monkey is separated by Sumatra from its sole congener on the Mentawai Islands. Pygathrix species have a discontinuous distribution at the range limit of the Asian Colobinae. The existence in the Himalayas of some disjunct relatives of the south Indian fauna, has obscured a wider disjunction in which for example, the hooded black leaf monkey, Semnopithecus johnii, has one subspecies in southern India and another in north Vietnam. A closely related Vietnamese leaf monkey is a subspecies of the otherwise Indonesian S. auralus. Presbytis comata is disjunct between west Java, northern Sumatra and northern Borneo. The Mentawai Islands P. potenziani is closely related. Biogeographic parallels imply a common cause and previous continuity across the intervening areas. The only wholly compatible explanation is that the disjunct areas alone retained adequate moisture and temperature to support their endemic biota during a cool drought. That not only genera, but species are disjunct, indicates such conditions prevailed recendy, and are probably attributable to the Pleistocene glaciations. The supposition that its maritime climate shielded Asian rainforest from the glacial drought known to have partially deforested Africa and South America, is inapplicable to the Indian subcontinent, and ignores the climatic effects of the emergence of the Sunda and the Sahul shelves. Such known influences, the distribution of drought indicator plants, fossil plants and fossil mammals, grassland birds and freshwater fish, and the anatomical specializations of Nasalis confirm the instability of the Asian environment. The absence of endemic representatives of certain primates in north Sumatra implies the occurrence of two cold droughts. Available evidence appears to correlate the deforestations with the abrupt curtailment of glacial Stages 7 and 5, at about 190 000 years BP and about 80 000 years BP. The greater significance of climatic than topographical barriers in delineating the Oriental zoogeographic region, and a rapid speciation rate, is implied. Morphological change is evidently generated by geographic dispersal, rather than geographic isolation. 相似文献
246.
Hartmut Jger 《Review of Palaeobotany and Palynology》2004,130(1-4):121-140
Palynological studies have been undertaken on Lower Carboniferous (Mississippian) rocks encountered in boreholes from the North Sea to the Baltic Sea (Rügen) in Northern Germany and from an outcrop at the northern border of the Rhenish Slate Mountains in western central Germany. The studied sections belong to different facies realms within the neritic shelf facies. They begin with very near shore coastal clastic facies in the North Sea and onshore Northern Germany, ranging into carbonate platform facies at Rügen, and then into platform slope facies at the northern margin of the Rhenish Slate Mountains. The focus of this study is the analysis of the relationship between sedimentary facies and spore assemblages; therefore, spores were considered only as sedimentary particles. Thus, it was necessary to create a new spore classification scheme based only on relevant sedimentary features. The new scheme distinguishes three classes of miospore based on shape, with each class subdivided into three subclasses based on features of ornament. The diversity of the spore assemblages and the total palynofacies have also been studied. Correlating palynological results from sections representing different sedimentary facies has led to a better understanding of the influence of sedimentary facies on spore assemblages. Correlations have been made at two stratigraphical levels. Regional correlation is undertaken on the Upper Viséan from the coastal clastic facies (North Sea, Northern Germany), the carbonate platform facies (Rügen) and the marginal platform slope facies (Velbert). Local correlation within the carbonate platform facies has been attempted using samples of Mid-Viséan TS zone from four boreholes on Rügen. Certain important differences have been observed. The local correlation at Rügen shows a decrease in spore frequency and spore assemblage diversity related to increasing resedimentation within subsided blocks of the platform. The composition of spore assemblages, strongly dominated by round-shaped spores, is nearly the same in all sections. The regional correlation shows clear proximal–distal trends for the total number of spores and also the diversity and composition of spore assemblages. A strong decrease in triangular and transitional spores from proximal to distal facies was observed. In conclusion, spore assemblages seem to be strongly influenced by sedimentary facies as well as by different sedimentary processes within the facies. Facies dependence of spore assemblages is shown to be an important factor for stratigraphical use of spores and for establishing vegetational and climatic trends. 相似文献
247.
248.
Cheng-hao Li 《Bioscience Hypotheses》2009,2(6):372-374
Cleft lip and palate is multifactorial in aetiology. The elevation of palatal shelves is a key point of palatogenesis. However, there were many different opinions on the explanation of the elevation. In this article, we offered a new explanation. Before sixth week of gestation in humans, Palatal mesenchymal proliferation was along the horizontal direction. Because of the block of the tongue, the palatal shelves had to grow first vertically in the oral cavity. In the process of cells migration, much horizontal stress accumulated in the palatal shelves, meanwhile increased the collagen secretion of the palatal mesenchymal cells in order to strengthen the elasticity of palatal shelf and maintain the integrity to make palatal shelf look like an elastic palate. The intrinsic elevating force and the block of tongue made the palatal shelf curved. After seventh week facial structures grew predominantly in the sagittal plane. The activity of the geniohyoid and genioglossus muscles caused the mandibular retraction and the widening of the angulation between the bilateral hemimandibles. These changes provided the space for palatal shelf elevation. At some moment of the eighth to tenth weeks, the elastic stress center of the palatal shelf was above the horizontal surface because of the drop of the tongue. The palatal shelves might bounce up and elevate in a horizontal position when enough horizontal stress accumulated, and then adhered and fused. 相似文献