Siliceous algal and bacterial stromatolites in hot spring and geyser effluents of yellowstone national park

Growing algal and bacterial stromatolites composed of nearly amorphous silica occur around hot springs and geysers in Yellowstone National Park, Wyoming. Some Precambrian stromatolites may be bacterial rather than algal, which has important implications in atmospheric evolution, since bacterial photo-synthesis does not release oxygen. Conophyton stromatolites were thought to have become extinct at the end of the Precambrian, but are still growing in hot spring effluents.     

Precambrian rift: genesis of strata-bound ore deposits

Study of deep seismic reflections has detected a Precambrian rift valley below flat-lying sediments in southern Alberta. The anomalous magnetic and gravity trends show that the rift is continuous across Alberta and British Columbia (through the Kimberley lead-zinc field) and possibly the Coeur d'Alene mining district of Idaho. There is evidence that these ore bodies were deposited in a Precambrian rift under conditions similar to those prevailing in the hot-brine areas of the modern Red Sea.     

Chitinozoans from the late precambrian chuar group of the grand canyon, Arizona

Carbonaceous shales of the late Precambrian Chuar Group of the Grand Canyon, Arizona, contain abundant and well-preserved chitinozoans. The occurrence of these distinctive, tear- and flask-shaped microfossils, the oldest chitinozoans now known and the first to be reported from the Precambrian, seems to suggest that heterotrophic protists (or primitive metaozoans) were extant at least as early as about 750 +/- 100 million years ago.     

武陵山片区特产的中国驰名商标与地理标志商标双重保护研究

分析了中国驰名商标、国家地理标志商标在我国的概况,对武陵山片区特产的中国驰名商标与地理标志商标双重保护问题进行了研究.在此基础上提出了相应的建议,即加强驰名商标的认定与保护、扩大其规模经济效益、对武陵山片区实行双重保护等.     

Microorganisms from the late precambrian of the grand canyon, Arizona

An assemblage of cellularly well-preserved, filamentous and spheroidal plant microfossils has been detected in a cherty pisolite bed of the late Precambrian Chuar Group from the eastern Grand Canyon of the Colorado River. This newly discovered microflora, probably among the youngest Precambrian biological communities now known, appears to be of both evolutionary and biostratigraphic significance.     

Microfossils in conophyton from the soviet union and their bearing on precambrian biostratigraphy

Silicified specimens of the Vendian (late Precambrian) "index fossil" Conophyton gaubitza from South Kazakstan contain a diverse assemblage of well-preserved cyanophytic and apparently eukaryotic algae, the first stromatolitic microbiota to be reported from the Soviet Union. Unlike the stromatolites in which they occur, the microorganisms that apparently built this form of Conophyton did not become extinct at the end of the Precambrian.     

The Origin of the Great Bend of the Nile from SIR-C/X-SAR Imagery

The course of the Nile in northern Sudan follows a contorted path through Precambrian bedrock. Radar imagery shows that basement structures control the river's course in this region. Northward-flowing segments follow Precambrian fabrics, whereas east-west segments follow faults of much younger age. These faults may reflect recent uplift of the Nubian Swell and deflection of the river to the southwest to form the great bend of the Nile.     

内蒙古西部湿地类型TM影像解译标志的建立

本文利用TM影像及相关数据,对内蒙古西部湿地做了全面的分析,总结了湿地的遥感影像特征,采用二级分类系统建立了湿地3类8个解译标志,通过室内样点预判与野外核查的对比,对解译标志的精度进行了评定,本次建立的解译标志的精度为88%,通过建立操作性较强的解译标志,对内蒙古西部湿地资源的动态监测和保护有着极其重要的意义。     

Ediacaran (precambrian) fossils from the wernecke mountains, northwestern Canada

Fossil medusoids identified as Cyclomedusa davidi?, Beltanelliformis brunsae, and cf. Sekwia excentrica are reported from Late Precambrian strata in the Wernecke Mountains. They are representatives of the Ediacaran fauna, the oldest assemblage of cosmopolitan metazoans, and are only the third such occurrence in Canada. In addition, specimens broadly resembling the problematic structure Rugoinfractus ovruchensis, previously known only from the Precambrian of the Ukraine, are reported from the Lower Cambrian of the nearby Mackenzie Mountains.     

Chromium and nickel in the fig tree shale from South Africa

Exceptionally high contents of chromium and nickel in shales from the early Precambrian Fig Tree series of South Africa ( 3.1 x 10(9) years old) suggest that the ancient crustal rocks from which these sediments were derived were ultramafic in composition.     

汉语引号的误用与日语学习中的负迁移

在国内发行的出版物中，我们经常看到，同样都是汉语表述的文章，在引用日语的词句时，却存在着使用汉语引号和日语引号两种情况。用汉语表述的文章，不管引用日语的是一个词，还是一段话，其引号理所当然地要参照和依据汉语言表述的相关规定或标准而规范使用，当用汉语引号，而不用日语引号。不规范使用日语引号乃是日语引号对中国日语学习者的负迁移使然。要修正汉语表述中日语引号的不规范使用现象，首先必须要清楚汉语的相关规定或标准，并要在心理上克服日语引号的干扰。     

Deep seismic expression of an ancient plate boundary in europe

Seismological results on the structure of the upper mantle below Europe reveal a marked contrast in seismic properties between Precambrian and younger parts of Europe. The Precambrian craton in eastern Europe is characterized by high shear-wave velocities, which can be explained by low temperatures. The transition to low seismic velocities below Phanerozoic Europe coincides with the crustal boundary zone of the craton and exists to depths of at least 140 kilometers. Despite the long and complex tectonic history of the plate boundary zone, the transition is remarkably sharp, which rules out any significant lateral transport of asthenospheric material across the suture zone.     

Composition of the ancient north american crust

Geochemical studies of Wyoming Precambrian graywackes derived from continental crust older than 3.2 x 10(9) years indicate that their source area was at least as highly differentiated as most younger Precambrian crust. The composition of this early crust (approximately that of calcium-rich granite) is not unlike that of the 2.5 to 3.2 x 10(9) year old North American crust. Limited geochemical data suggest that the composition of North America may not have changed significantly during the last 3.0 to 3.5 x 10(9) years.     

海南热带特色农产品地理标志管理模式探索

简述了地理标志农产品定义及特点,分析了海南省地理标志农产品管理存在的问题,探索了海南特色农产品地理标志信息化管理模式,并对海南省地理标志产品建设提出了政策建议。     

Algal fossils from a late precambrian, hypersaline lagoon

Organically preserved algal microfossils from the Ringwood evaporite deposit in the Gillen Member of the Bitter Springs Formation (late Precambrian of central Australia) are of small size, low diversity, and probable prokaryotic affinities. These rather primitive characteristics appear to reflect the stressful conditions that prevailed in a periodically stagnant, hypersaline lagoon. This assemblage (especially in comparison with the much more diverse assemblages preserved in the Loves Creek Member of the same formation) illustrates the potential utility of Proterozoic microbiotas for basin analysis and local stratigraphic correlation and demonstrates the need to base evolutionary considerations and Precambrian intercontinental biostratigraphy on biotas that inhabited less restricted environments.     

How old are the eukaryotes?

Evidence from Precambrian sediments appears to indicate that nucleated (eukaryotic) organisms had become well established and relatively diverse about 850 +/- 100 million years ago and that eukaryotes were probably extant, and may have first appeared, as early as 1400 +/- 100 million years ago.     

棉花抗低温生理指标和分子标记鉴定体系研究

[目的]研究低温胁迫下棉花生理生化指标,筛选确定棉花抗低温的特异分子标记引物.[方法]通过对30份农艺性状优良、抗低温程度不同的棉花材料在室内进行24 h 3℃低温胁迫处理,测定胁迫前后7项生理生化指标;从Genbank中调出与抗低温相关的基因片段,利用生物软件Oligo6.0处理并设计引物,筛选出与棉花抗低温基因序列相关分子标记的特异引物.[结果]建立与棉花抗低温相关生理生化鉴定指标3项,开发了与棉花抗低温相关的特异分子标记2对,筛选出抗低温材料5份.[结论]建立了棉花抗低温生理生化指标与特异引物分子标记相结合的鉴定体系.     

X-Chromosome inactivation in cloned mouse embryos

To study whether cloning resets the epigenetic differences between the two X chromosomes of a somatic female nucleus, we monitored X inactivation in cloned mouse embryos. Both X chromosomes were active during cleavage of cloned embryos, followed by random X inactivation in the embryo proper. In the trophectoderm (TE), X inactivation was nonrandom with the inactivated X of the somatic donor being chosen for inactivation. When female embryonic stem cells with two active X chromosomes were used as donors, random X inactivation was seen in the TE and embryo. These results demonstrate that epigenetic marks can be removed and reestablished on either X chromosome during cloning. Our results also suggest that the epigenetic marks imposed on the X chromosomes during gametogenesis, responsible for normal imprinted X inactivation in the TE, are functionally equivalent to the marks imposed on the chromosomes during somatic X inactivation.     

Mammalian pheromone: identification of active component in the subauricular scent of the male pronghorn

Male pronghorn (Antilocapra americana) mark vegetation by rubbing with their subauricular glands. Males respond to scent marks by sniffing, licking, thrashing, and marking. Hand-raised males were confronted with artificial scent marks consisting of whole extract of the subauricular gland or synthesized compounds corresponding to those identified from the extract. Of these, isovaleric acid released the strongest responses.     

Neodymium and strontium isotope evidence for crustal contamination of continental volcanics

Combined neodymium and strontium isotope studies on Tertiary volcanics from northwest Scotland indicate that their parental mantle isotopic compositions have been substantially modified in many instances by contamination with the Precambrian continental crust through which they were erupted. The occurrence of samarium-neodymium and rubidium-strontium "pseudoisochrons" of different ages in these contaminated continental volcanics indicates that they are artifacts of the contamination processes and have no temporal significance with respect to mantle fractionation events.