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81.
中国东北草原植物中的C3和C4光合作用途径   总被引:32,自引:8,他引:32  
殷立娟  王萍 《生态学报》1997,17(2):113-123
以光合作用关键羧化酶PEPC和RuBPC活性化,并且参照叶片CO补偿浓度,δ^13C值和叶片解剖结构特点来鉴定东北草原区233种植物的C3,或C4光全作用途径,这些植物隶属于144属73科,其中137种为首次鉴定。89种具有C4光合作用途径,隶属于55属17科;144种人有C3光俣作用途径;隶属于94属28在多数C4种分布在禾本科、莎草科、苋科和藜科。苋属、地肤属、狗昌属和虎尾草属中的均为C4植物  相似文献   
82.
首次从啮齿类和食虫类动物中分离到森林脑炎病毒   总被引:1,自引:0,他引:1  
1988年,我们从采自云南高黎贡山的卵形硬蜱及患者血液中分离到森林脑炎病毒。1990年,又从该地区10种95只啮齿类中查到森林脑炎病毒抗体;并从社鼠(R.confucianus)、小林姬鼠(A.sylvaticus)和灰腹鼠(R.eha ninus)等8种啮齿类及食虫类中分离到15株病毒,选三株用单克隆抗体进行免疫荧光试验、理化特性、生物学特性及中和试验研究。结果表明,其病毒的抗原性、生物学特性及理化特性与东北株及从卵形硬蜱、患者分离的森林脑炎病毒一致。从啮齿类及食虫类分离到森林脑炎病毒在国内属首次报道。这项研究结果进一步证明,啮食类和食虫类在森林脑炎自然疫源地的保存方面起重要作用。  相似文献   
83.
Natural habitat preservation, i.e. the creation and management of Protected Natural Areas (PNAs), is one of the most important forms of biodiversity conservation. The most widespread types of PNAs in Russia are Zakazniks (State Nature Refuges) and Natural Monuments, but unlike Zapovedniks (State Nature Reserves) these types of Russian PNAs are little-known to foreign ecologists. Thus the main attention of this article is given to the problems of Zakazniks and Natural Monuments while other types of Russian PNAs are mentioned briefly. In many regions of Russia, Zakazniks and Natural Monuments are considered to be the core components for the regional protection of biodiversity. Non-Governmental Organizations play an important role in the creation and management of PNAs. The recent sudden change of circumstances in Russia have given rise to many problems which threaten the existence of Zakazniks and Natural Monuments. Possible means of saving these PNAs include: (i) promoting the interest of local people in protecting biodiversity; and (ii) supporting local authorities, and public initiatives and regional programmes in the creation of local PNA networks.  相似文献   
84.
A new subfamily, genus, and species (Deinotitaninae subfam. nov., Deinotitan orenburgensis gen. et sp. nov.) of the family Mesotitanidae (Titanoptera) are described from the Severodvinian (Upper Permian) of the Orenburg Region. This family belongs to the suborder Mesotitanina; both are recorded in the Paleozoic for the first time. The present finding and unpublished data suggest that the Mesozoic stage of the evolution of the superorder Orthopteroidea might start in the Late Permian. Taxonomy and early evolution of the order Titanoptera are discussed. Minititan nom. nov. is proposed for Microtitan Gorochov, 2003 (nec Microtitan Granger et Gregory, 1943).  相似文献   
85.
Fragments of the anterior part of a mandibular rostrum and a maxillary bone of the plesiosaur Polycotylidae indet. from the Karyakino and Beloe Ozero localities of the Saratov Region (Upper Cretaceous, Campanian) are described. The specimens belong to a relatively long-snouted polycotylid with a mandibular symphysis incorporating 13 pairs of teeth. A unique feature of this plesiosaur is the fact that, in the symphysis, the splenial extends to the very anterior end of the rostrum. The polycotylid from the Campanian of the Saratov Region is probably closely related or identical to Georgiasaurus from the Santonian of the Penza Region, in which structural details of the mandibular symphysis remain uncertain.  相似文献   
86.
87.
Heat stress, when combined with drought, is one of the major limitations to food production worldwide, especially in areas that use rainfed agriculture. As the world population continues to grow, and water resources for the crop production decline and temperature increases, so the development of heat- and drought-tolerant cultivars is an issue of global concern. In this context, four barley and two wheat genotypes were evaluated in south-eastern Russia to identify heat- and drought-tolerant genotypes for future breeding programmes by identifying suitable sowing times for specific genotypes. High temperature stress, when combined with drought during late sowing, decreased the days to visible awns, days to heading and days to ripe harvest, finally negatively affecting the growth and development of plants and resulting in a lower plant population m−2, tillers plant−1, plant height and dry matter production m−2. On the other hand, low temperature in combination with early sowing increased the number of days to germination, reduced seedling stand establishment and tillering capacity, finally affecting the growth and development of the crops. Compared to overall performance and optimum sowing date, barley genotypes ‘Zernograd.770’ and ‘Nutans’, and wheat genotype ‘Line4’ performed best in both late (high temperature with drought) and early (low temperature) stress conditions.  相似文献   
88.
Three new conodont species, Streptognathodus neverovensis, S. isakovae, and Idiognathodus mestsherensis, which are widespread in the Kasimovian Stage of central Russia, are described.  相似文献   
89.
Precambrian fossils are crucial for our understanding of the evolution of early organisms. Megascopic body fossils are more important because they potentially represent macroorganisms. However, the Precambrian fossil record is sparse and dominated by microfossils and microbial structures. Here we show a new type of megascopic fossils recovered from the Xingmincun Formation (probably Neoproterozoic age), northeastern China. The specimens are flat, flexible (easily corrugated) and discoidal in outline. Concentric or spiral ridges are preserved on both sides. Petrographical thin section examination indicates that the specimen consist of a thin layer of microcrystalline quartz grains (about 20–30 μm thick) wrapped by an outer sheath, composed primarily of chlorites. Field Emission Scanning Electron Microscopy (FE-SEM) coupled with an x-ray energy dispersive spectrometer system (EDX) analysis shows microstructures and relative element abundance of the fossils, but contributes little in solving their biological affinities. The fossils have previously been linked to discoidal impressions of the Ediacara biota. Close examination on new materials indicates that they are radically different from either the Ediacara impressions or any other Precambrian megascopic remains. Concentric or spiral ridges may result from rhythmic growth and the presence of twin specimens may suggest that the organisms undergo asexual reproduction or inhibition of growth in one direction. Referring them to any known fossil or living group has proved to be difficult. We conclude that they represent a distinct group of Precambrian megascopic organisms regardless of their affinities remaining problematic.  相似文献   
90.
Over the last few years anomalies in temperature and precipitation in northern Russia have been regarded as manifestations of climate change. During the same period exceptional forest fire seasons have been reported, prompting many authors to suggest that these in turn are due to climate change. In this paper, we examine the number and areal extent of forest fires across boreal Russia for the period 2002-2005 within two forest categories: 'intact forests' and 'non-intact forests'. Results show a far lower density of fire events in intact forests (5-14 times less) and that those events tend to be in the first 10 km buffer zone inside intact forest areas. Results also show that, during exceptional climatic years (2002 and 2003), fire event density is twice that found during normal years (2004 and 2005) and average areal extent of fire events (burned area) in intact forests is 2.5 times larger than normal. These results suggest that a majority of the fire events in boreal Russia are of human origin and a maximum of one-third of their impact (areal extension) can be attributed to climate anomalies alone, the rest being due to the combined effect of human disturbances and climate anomalies.  相似文献   
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