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961.
洋县绿豆梁遗址位于汉水北部一级支流金水河左岸的第四级阶地上。为了配合国家重点工程项目——南水北调西线“引汉济渭”工程的建设,2014~2015年对该地点进行了发掘,揭露面积126 m2,出土和采集不同类型的石制品656件。研究显示,早期人类加工石制品的原料来自于河漫滩或阶地古老砾石层中的砾石,岩性包括石英、石英岩、硅质灰岩、石英砂岩、花岗岩等。硬锤打击法是最主要的剥片方式。石制品包含石锤、石核、石片、石器、断块和碎屑等类型。遗址石器组合中既包括刮削器、尖状器、石钻等尺寸较小的轻型石器,也包含重型刮削器、砍砸器等重型石器。通过与位于相同阶地部位、相距2 km的金水河口遗址的测年数据和地层堆积序列对比,绿豆梁遗址的年代属于中更新世时期或更早的时段。  相似文献   
962.
云南西部高黎贡山地区生物多样性既丰富又受威胁。当地公众不珍惜自然、无保护常识。为拯救该地区生物资源,笔者深入基层山区村户、不拘形式或小型非正式座谈讨论方式,对1000余人进行了公众保护意识教育,使他们懂得了生物资源的保护与持续利用益在自身和长久,控制狩猎和择猎以确保野生动物种群稳定,改变“刀耕火种”、以计划限量采伐维护森林环境等。文中对未来公众保护教育提出了建议  相似文献   
963.
Water hyacinth,Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae) was first reported in Bénin in 1977 and about 10 years later became the major floating water weed in the south east, obstructing boat traffic and fisheries. Water hyacinth multiplies in permanently fresh water in the swampy upper reaches of the Sô River and in tributaries of the Ouémé River. From there it is moved by wind and water flow to the coastal lagoons. The coastal lagoons are brackish during the dry season and water hyacinth eventually dies. In 1991,Neochetina eichhorniae (Warner) (Col.: Curculionidae) of South American origin was imported from Australia via quarantine in Britain to Bénin. A small infestation of the fungusBeauveria bassiana (Bals.) Vuill. (Hyphomycetes) was eliminated from the colony before release by sterilizing eggs and rearing a fungus-free generation. Between late 1991 and mid 1993, about 23,900N. eichhorniae were released at 11 localities along the Ouémé River and in the head waters of the Sô River. Regular monitoring revealed feeding scars by adults on leaves and tunnelling by larvae in petioles at all release sites. By October 1993,N. eichhorniae had spread up to 20 km from some release sites.Neochetina bruchi Hustache was imported in 1992. A total of about 5,700 weevils has been released in six localities since mid 1992. Recoveries of offspring were made in all but one locality. Despite the negative impact of water flow, wind, penetration of salt water, and removal of infested water hyacinth by fishermen,N. eichhorniae andN. bruchi are established in Bénin in a situation typical for coastal West Africa.  相似文献   
964.
The effects of habitat and timing of growing season fires on resprouting of shrubs were studied in second-growth longleaf pine savannas of the west Gulf coastal plain in the southeastern United States. Within the headwaters of three different drainages of the Calcasieu River in the Kisatchie National Forest in western Louisiana, replicated permanent transects were established that extended from xeric upland longleaf pine savannas into downslope hydric seepage savannas. All shrubs were mapped and tagged, and numbers of stems were counted prior to any fires. Replicated prescribed fires were set early (June) and late (August) during the 1990 growing season; maximum fire temperatures were measured within both upland and seepage habitats within each transect. Shrubs were relocated; stems were recensused two and twelve months after the fires. At least some shrubs of all species resprouted from underground organs; none regenerated solely from seed banks in the soil. There was no reduction in total numbers of stems one year after fires compared to before fires, either in the upland or in seepage savannas. In addition, there was no reduction in total numbers of stems one year after early or late growing season fires. Fire-related mortality was restricted to small shrubs (< 18 stems) and was not associated with high fire temperatures. The rate of resprouting varied among species and between habitats. Resprouting occurred more rapidly in seepage than upland savannas, but more resprouts were produced in upland than seepage savannas one year after fires. In contrast to other upland species, Vaccinium arboreum and V. elliottii delayed resprouting more than two months following fire. Stems of Rhus copallina and Pyrus arbutifolia, species with long rhizomes, increased more after fires in June than fires in August. We suggest that growing season fires may block further recruitment of shrubs into longleaf pine savannas, but reduction in numbers of large shrubs may require additional management.  相似文献   
965.
Simone Pouyet 《Geobios》1978,11(5):611-621
The bryozoa described by de Lamarck in 1816 are not well known. Four types of the Cellepora group have been found in the zoological collections of Museum d'Histoire naturelle in Paris: Celleporaria oculata, C. cristata, C. oliva and C. endivia. C. oculata is the type-species of the genus CelleporariaLamouroux, 1821. This revision confirms the synonymy of some species described subsequently.  相似文献   
966.
Red cell antigen, serum protein and red cell enzyme groups were determined for a series of 1,821 individuals belonging to six language families in Western New Guinea. Three of the language families represent groupings of languages spoken by people in the swampy coastal plain of south central Western New Guinea, two belong to the Central Highlands and one to the Lake Plain area near the confluence of the Idenburg and Rouffaer Rivers. The distribution of genetic markers reveals similarities with other parts of New Guinea. The A2 allele is absent in the ABO system, the frequency of Ns in the MNS system is very high as is the R1 (CDe) allele in the Rh system. Hp1 frequencies are high, and the transferrin allele TfD 1 is present as in other parts of New Guinea. In the red cell enzyme systems several alleles were detected which are characteristic of Papuan, and in some cases other Melanesian populations: these include MDH3, PGK4, PGK2, PGM92, PGM102, as well as some very restricted alleles such as Peptidase B6 and Pep B2. Three indices of genetic distance were computed. The most striking results are the genetic closeness of the Dani and Moni populations from the Central Highlands to the Asmat on the southern coastal plain, and the relative remoteness of the Awyu from the other south coastal populations. The results are discussed in terms of recent theories on the origin and dispersal of Papuan languages.  相似文献   
967.
An improved gas chromatographic method for the determination of total, i.e., amide- and ester-linked, acetyl groups in hydrolysates of bacterial lipopolysaccharides has been developed. After hydrolysis with 0.2 n HCl overnight at 100°C and adjustment of the hydrolysate to pH 3–4, 2 μl of the samples contalning 0–6 μg of acetic and 1–2 μg of propionic acid are directly injected into a gas chromatograph fitted with a 1.5-m glass column packed with Porapak QS. O-Acetyl groups can selectively be determined after hydrolysis with 0.05 n NaOH for 3–4 hr at room temperature and adjustment of the sample to pH 3–4. N-Acetyl groups can be calculated as the difference between total and O-acetyl. The above-mentioned phase allows quantitation of short-chain volatile fatty acids (S-C VFAs) up to n-valeric acid in a range of 0–6.0 μmol using an appropriate internal standard.  相似文献   
968.
An immunoaffinity chromatography procedure for the isolation of bovine glial fibrillary acidic (GFA) protein is described. Degraded GFA protein isolated by hydroxyapatite chromatography from human spinal cord was used to prepare the antiserum. The immunoglogulin G fraction of the antiserum was covalently linked to CNBr-activated Sepharose, and columns of the immuno-affinity gel were used to adsorb bovine GFA protein from brain extracts. Elution was accomplished with a solution of 1 m acetic acid, 5 m urea, 0.8 m sodium chloride, pH 2.5. The yield of about 0.5 mg of highly purified protein/g of cerebral white matter could be increased to 1.5 mg/g of tissue by lowering the ionic strength of the extracting buffer from 50 mm to 1 mm sodium phosphate. Isolation in the presence of EDTA prevented the formation of an oxidation product migrating as a dimer of the monomeric species on SDS-polyacrylamide gel electrophoresis.  相似文献   
969.
A comparison of rat brain and liver β-hydroxybutyrate dehydrogenase (EC 1.1.1.30) has revealed that significant differences exist between the enzymes with regard to their kinetic and physical properties. In contrast to the liver enzyme, brain β-hydroxybutyrate dehydrogenase is rapidly inactivated at 46° and is unstable when stored at ?20°. The brain dehydrogenase was found to have a larger Km (apparent) for the 3-acetylpyridine analog of NAD+, and a greater energy of activation in the direction of β-hydroxybutyrate oxidation than the liver enzyme. In the reverse direction, the brain and liver dehydrogenase exhibit substrate inhibition by NADH (0.22 mM and 0.36 mM, respectively). The brain and liver β-hydroxybutyrate dehydrogenase did not differ significantly with regard to the Michaelis-Menten constants measured for NAD+ and β-hydroxybutyrate. The Km constants of brain β-hydroxybutyrate dehydrogenase for acetoacetate (0.39 mM) and NADH (0.05 mM) were lower than those determined for the liver enzyme, acetoacetate (0.73 mM) and NADH (0.35 mM) respectively. These results suggest that the β-hydroxybutyrate dehydrogenase from rat brain and liver are isozymic variants.  相似文献   
970.
Grass water stress estimated from phytoliths in West Africa   总被引:2,自引:0,他引:2  
Aim This study calibrates the relationship between phytolith indices, modern vegetation structure, and a climate parameter (AET/PET, i.e. the ratio of annual actual evapotranspiration to annual potential evapotranspiration), in order to present new proxies for long‐term Quaternary climate and vegetation changes, and model/data comparisons. Location Sixty‐two modern soil surface samples from West Africa (Mauritania and Senegal), collected along a latitudinal transect across four bioclimatic zones, were analysed. Methods Two phytolith indices are defined as normalized data: (1) humidity‐aridity index [Iph (%) = saddle vs. cross + dumbbell + saddle], and (2) water stress index [fan‐shaped index (Fs) (%) = fan‐shaped vs. sum of characteristic phytoliths]. Vegetation structures are delimited according to Iph and Fs boundaries. Bootstrapped regression methods are used for evaluating the strength of the relationship between the two phytolith indices and AET/PET. Additional modern phytolith assemblages, from Mexico, Cameroon and Tanzania are extracted in order to test the calibration established from the West African samples. Accuracy of the AET/PET phytolith proxy is compared with equivalent pollen proxy from the same area. Results Characterization of the grass cover is accurately made through Iph. A boundary of 20 ± 1.4% discriminates tall grass savannas from short grass savannas. Water stress and transpiration experienced by the grass cover can be estimated through Fs. AET/PET is accurately estimated from phytoliths by a transfer function: AET/PET = ?0.605 Fs ? 0.387 Iph + 0.272 (Iph – 20)2 (r = 0.80 ± 0.04) in the application domain (AET/PET ranging from 0.1 ± 0.04 to 0.45 ± 0.04). Phytolith and pollen estimate with similar precision (rpollen = 0.84 ± 0.04) the AET/PET in the studied area. Conclusions This study demonstrates that we can rely on the phytolith indices Iph and Fs to distinguish the different grasslands in tropical areas. Moreover, a new phytolith proxy of AET/PET, linked to water availability, is presented. We suggest from these results that combining phytolith and pollen proxies of AET/PET would help to constrain this climate parameter better, especially when phytolith assemblages are dominated by Panicoideae and Chloridoideae C4‐grass phytoliths, are devoid of Pooideae C3‐grass phytoliths, and occur with a few tropical ligneous woody dicotyledon phytoliths. As AET/PET is a bioclimatic indicator commonly used in vegetation models, such a combination would help to make model/data comparisons more efficient.  相似文献   
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