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1.
Florin Ioras Ioan Vasile Abrudan Mirza Dautbasic Mersudin Avdibegovic Dan Gurean J. Ratnasingam 《Biodiversity and Conservation》2009,18(13):3395-3406
This paper analyses the conservation gains through High Conservation Value Forest (HCVF) assessments in two South-East European
countries (Bosnia-Herzegovina and Romania). These are based on the review of the Draft Forest Stewardship Council (FSC) National
Standards and HCVF Manuals and the results of the certification process of seven forest management units in the two countries.
The review indicates that the application of Principle 9 (High Conservation Value Forests) and Criterion 6.4 of the FSC in
Bosnia-Herzegovina and Romania was influenced by the size and nature of tenure (i.e., public or non-public land), rather than
geographic location per se. The study also revealed that the assessment of HCVF has, for the first time, raised the question
of conservation of cultural, historical and religious values as well as the sustainable management of those forests relevant
for the basic needs of communities. These are values not currently covered at the present by the national conservation legislation
in either of these two countries. Findings of this study in both countries demonstrates that there are certain conservation
gains as a result of the HCVF assessment, especially related to ecosystem services, prevention of soil erosion and conservation
of threatened, endangered and endemic species. 相似文献
2.
12株猪瘟病毒E2基因主要抗原区域的序列差异分析 总被引:14,自引:0,他引:14
用RTPCR扩增了12个不同时期分离的HCV毒株E2基因主要抗原区域的cDNA片段并对其进行了序列测定。应用DNAstar序列分析软件对所测的12个HCV毒株与国内外已知的6个毒株Alfort株、Ald株、Brescia株、Gpe株、C株、CW株及早期已测定的HCLV株、HCVSM株和北京顺义株(BJSY2/96)3个毒株的相应片段进行了同源性比较分析。E2基因主要区域长度均为224 bp,包括从HCV 2485到2708位的E2基因B、C区域。所测的疫苗株HCLV与国外测得的疫苗株C株核苷酸及氨基酸同源性分别为991%和100%,表明目前应用的疫苗株是稳定的;用目前我国流行的部分野毒株对HCLV株免疫猪的攻击试验表明,HCLV对野毒株均具有很好的免疫力,这与序列分析结果相吻合。根据系统树分析,可将HCV分为两大群,5株90年代的野毒株及1株80年代的野毒株(其中北京3株、河南2株、广东1株)均与国内外C株、标准株属同一群(即第一群),其核苷酸及氨基酸的同源性分别为857%~100%和838%~100%;与Alfort株同属第二群的有6个野毒株(广西北海、辽宁、河北黄骅、吉林、深圳光明、四川成都),其中80年代与90年代的野毒株各有三株,核苷酸及氨基酸的同源性分别为843%~100%和851%~100%;21株HCV的核苷酸及氨基酸的同源性分别为781%~100%和784%~100%。两群之间的特征性差异表现在713和729位氨基酸位点的不同,经分析发现猪瘟野毒株具有复杂性与多样性。 相似文献
3.
H Leonhardt L Schulz H Zuther-Witzsch 《Zeitschrift für mikroskopisch-anatomische Forschung》1975,89(2):264-284
The ependymal surface of the area postrema (rabitt) was examined by scanning and transmission electron microscopy. The flattened ependymal cells show few microvilli. Towards the central canal, the ependymal cells change gradually to a columnar shape; the number of microvilli increases concomitantly. The area postrema ependymal cell surface mostly bears a single cilia. In contrast, a region immediately adjacent to the area postrema, which has been named area subpostrema (Gwyn and Wolstencroft 1968), shows cilia arranged in bunches. These cilia are regularly covered with colloid -- like droplets. A period-acid-bisulfit-aldehydthionine method (Specht 1970) permits to identify these droplets with glyproteids.it has been suggested that the droplets might derive from the area subpostrema ependymal cells. Above the ependymal surface of the area postrema, a great number of fine unmyelinated neuronal processes and thicker processes are observed. Some of them show bulb-like endings. These terminals contain small vesicles, dense cored vesicles (400...800 A), and mitochondria which are mostly characterized by a single central prismatic tubule. The plasmalemma of some bulbs is in a synaptic contact with the apical plasmalemma of the ependyma, while other bulbs see to end freely in the ventricle. Some neuronal processes penetrate between ependymal cells of the area postrema into the ventricular lumen. 相似文献
4.
Knowledge of the surface area of cells is necessary for biophysical studies in which the permeability coefficient of a cell-type for a solute is defined. Under the microscope, avian erythrocytes have the appearance of an oval discus usually with a central elongated nucleus. The dimensions of these cells have been obtained for a large range of species over the past century. However, estimates of the surface areas have been obtained using mathematically simplistic models such as flattened circular cylinders. We modelled red cells of the domestic chicken (Gallus domesticus) as ellipsoids using the previously published dimensions to obtain the three semi-axis lengths. Although the mathematical expression for the volume of an ellipsoid is well known, an expression for the surface area is not. We present a general expression for the surface area of an ellipsoid that is a power series involving elliptic integrals and functions; the latter being rapidly evaluated by computer using standard series expressions. Our estimates of area are compared with earlier ones and those obtained by numerical integration of the surface. 相似文献
5.
The best-known macroecological generalisation is the species/area relationship: larger areas contain more species. It has also been observed that the estimated densities of individual species is lower when they are censused over a larger area. Let us call this the density/area relationship. Numerous explanations for the density/area relationship have been proposed – including the idea that the relationship is artefactual. One possible explanation is that it is a necessary consequence of the species/area relationship – after all, if a larger area is to contain more species then the average abundance of individual species must decline. We study a data set that allows us to study both relationships simultaneously. We conclude that the density/area relationship observed for the individual species in this study is consistent with the species/area relationship explanation: in other words, the densities of individual species decline, quantitatively, in the manner required to fit more species into communities with larger areas. We conclude that whatever explains the species/area relationship also explains the density/area relationship and discuss, in particular, the habitat heterogeneity hypothesis. 相似文献
6.
The hydrology of the Loosdrecht lakes area 总被引:5,自引:5,他引:0
7.
N V Synkova 《Arkhiv anatomii, gistologii i émbriologii》1984,86(5):43-49
After injecting Indian ink--gelatin mass and vegetable peroxidase, parameters of microvessels in the rat gastric tunica serosa have been measured. The capillary diameters make 3.99 and 4.1 mcm, their length--240 and 259 mcm, density of the tunica serosa are--31 and 26 per 1 mm2. Using these parameters and the value of the hydraulic conductivity, the total area of the capillaries surface (0.09 mm2) and the volume of the filtrated (3.8 X 10(3) mcm3) and reabsorbed (115 X 10(3) mcm3) liquors are calculated. Comparing the volumes of the liquor transported in the visceral layer of the peritoneum and in its other parts, it is possible to consider the mechanisms maintaining water balance in the peritoneal cavity. 相似文献
8.
Cytochemistry of the gas-exchange area in vertebrate lungs 总被引:2,自引:0,他引:2
C Meban 《Progress in histochemistry and cytochemistry》1987,17(1):1-54
Considerable progress has been made in the localization of chemical substances within the gas-exchange zones of vertebrate lungs since cytochemical techniques suitable for use with the electron microscope have been developed. The light microscope, an instrument with an effective resolution limit of about 0.2 micron, is ill-suited for studying regions such as these where small tissue elements are arranged in a complex manner. A wide range of acid hydrolases have been detected in the vacuoles and dense bodies of alveolar macrophages by means of cytochemical techniques. The enzymes demonstrated in this way include acid phosphatase, aryl sulphatase, cathepsin D, beta-glucuronidase, acetyl glucosaminidase, nonspecific esterase, dipeptidyl peptidase II and dipeptidyl peptidase IV. Such enzymes are, of course, to be expected in the lysosomes of cells which have a primary phagocytic role. Nevertheless, it must be confessed that very little is yet known about the actual mechanism of phagocytosis or of the fate of the digested material. It is fortunate, however, that some of the tools which are likely to be of value in research on these aspects of macrophage function are currently being developed. Of particular interest in this connection are the immunocytochemical techniques which permit the localization of surface-associated antigens and intracellular contractile proteins. It must be emphasized that phagocytosis is not the only function of macrophages in the gas-exchange zone of the lung. These cells are thought to be involved in the presentation of exogenous antigenic material to the reactive cells of the lymphoid system. Recent research has also indicated that mammalian alveolar macrophages synthesize a diverse range of substances. Furthermore, the elastases associated with pulmonary macrophages are now thought to be involved in the pathogenesis of emphysema. All of the above-mentioned activities are of great biological and clinical significance and, consequently, merit the cytochemists' attention in future. The epithelial lining of the greater part of the pulmonary gas-exchange area is composed of type I pneumonocytes. In terms of ultrastructure, these are very specialized cells; their extensive and highly-attenuated cytoplasmic processes form the outer layer of the air-blood barrier. No special carrier systems have been identified within type I pneumonocytes and this is in keeping with the claims that oxygen is transferred across the alveolar tissue barrier by a process of simple diffusion. Type II pneumonocytes, in contrast, have considerable metabolic activity.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
9.
I. Törk 《Histochemistry and cell biology》1970,22(1):67-78
Summary Detailed studies were made on the distribution of carboxylic esterases in the area postrema (AP) of the guinea pig. In this species the nerve cells of the AP show intense acetylcholinesterase activity which greatly enhances a morphological study of these elements. The two main types of nerve cells arebipolar cells andmultipolar cells. The bipolar cells often send their peripheral processes to the wall of a capillary, while the other processes go towards the nervous tissues outside of the organ. A similar behavior of the processes could be observed in the case of the multipolar cells. A special multipolar cell having bulb-like endings in the neuropilema of the organ has been discussed. On the basis of these findings it is conjectured that these neural elements, as well as the AChE positive nerve fibers located along the walls of the capillaries, function as parts of a chemoreceptor system, the existence of which has been postulated by former authors. The non-specific esterase activity of the organ is rather diffuse. B esterases have been described in the glial cells and in several nerve cells and in the pericytes and endothelial cells of the perivascular space. The localization of A and C esterases appeared diffuse, but only the AP showed intense C esterase activity in the caudal medullary area. 相似文献
10.
Impacts of human activity on environment in the high-cold pasturing area: A case of Gannan pasturing area
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Identifying the specific forces driving environmental impact is a hot topic in the field of sustainable development in the pasturing area. In the paper, the ecological footprint was taken as the index of environmental impact, and a series of index like population quality, prosperous, using intensity, livelihood tactics are considered as the main human factors. Using the STIRPAT model and temporal series data from 1980 to 2007, the author analyzes the effects of the human driving forces of environmental impact.
The ecological footprint method presents a simple framework for national natural capital accounting, and it has been used as a comprehensive index of human activity impact, which indirectly reflect human activity’s pressure on the environment. Our analyses showed that the ecological footprint increased from 238736.9 to 877716.1 ha and per capital ecological footprint also increased from 0.854 to 1.961 ha/per during 1980–2007 in Gannan pasturing area. However, in the meantime, the ecological footprint intensity was inclined from 25.396 to 3.025 ha/ten thousand yuan.
With a view of dismantling the human driving forces of ecological footprint, the modified IPAT-called STIRPAT has been employed as a common analytic framework. Our analyses showed that population quantity and using intensity was a major driver of ecological footprint, their coefficients were greater than 1.0 in model (1); In addition, promoting the prosperous lever and the primary industry proportion, the impact of environment will be increased, but their coefficients are less than 1.0 in model (1). At the same time, the technological eco-efficiency of sample regions was discussed in details, the range ability of the technological eco-efficiency was wider, and 15 years went beyond the average level, but the other was less than the average level. Another important finding in the empirical study is that there are some evidences of an environmental Kuznets curve for ecological footprint within the range of calculated data. Some potential improvements in some further researches and suggestions to alleviate the environment pressure, and it is put forward in the last section. 相似文献
The ecological footprint method presents a simple framework for national natural capital accounting, and it has been used as a comprehensive index of human activity impact, which indirectly reflect human activity’s pressure on the environment. Our analyses showed that the ecological footprint increased from 238736.9 to 877716.1 ha and per capital ecological footprint also increased from 0.854 to 1.961 ha/per during 1980–2007 in Gannan pasturing area. However, in the meantime, the ecological footprint intensity was inclined from 25.396 to 3.025 ha/ten thousand yuan.
With a view of dismantling the human driving forces of ecological footprint, the modified IPAT-called STIRPAT has been employed as a common analytic framework. Our analyses showed that population quantity and using intensity was a major driver of ecological footprint, their coefficients were greater than 1.0 in model (1); In addition, promoting the prosperous lever and the primary industry proportion, the impact of environment will be increased, but their coefficients are less than 1.0 in model (1). At the same time, the technological eco-efficiency of sample regions was discussed in details, the range ability of the technological eco-efficiency was wider, and 15 years went beyond the average level, but the other was less than the average level. Another important finding in the empirical study is that there are some evidences of an environmental Kuznets curve for ecological footprint within the range of calculated data. Some potential improvements in some further researches and suggestions to alleviate the environment pressure, and it is put forward in the last section. 相似文献
11.
Simone Fattorini 《Biodiversity and Conservation》2014,23(10):2545-2560
Most studies have attempted to identify the major environmental factors responsible for elevational variations in species richness. Such studies have been mainly performed in temperate and tropical areas, whereas the mediterranean biome has been substantially neglected. The aim of this paper was to disentangle the effects of available area, mid-domain constraints, and the environmental tolerance of species, on the altitudinal distribution of tenebrionid beetles in a Mediterranean region. A comprehensive faunistic database was used to assess the elevational distribution of tenebrionids in Latium (Central Italy). Variations in species richness, beta diversity and nestedness were analysed in association with variation in species ranges and midpoints. Variation in species richness was contrasted with patterns expected on the basis of the mid domain effect (MDE) and available surface area. After correcting for differences in area availability due to the conical shape of mountains, an unexpected triphasic pattern emerged: (1) at low altitudes, species richness was higher than expected on the basis of the effect of area and the MDE; (2) at around 800 m elevation, there is an abrupt change in species assemblages, and richness values fit those predicted by the MDE; (3) a new dramatic change occurred at 1,700 m, with tenebrionid assemblages composed of a small number of mainly eurytopic species. The integrated approach used in this study demonstrates that neither MDE nor monotonic patterns fully explain the observed diversity patterns. Variations in species ranges indicate that the elevational gradient filters species according to their ecological tolerance. 相似文献
12.
In earlier works we have investigated the correlation between aerobiological and phytogcographical data, assessing the presence and number of the most important allergenic taxa in our area. More recently we have enquired into the relationship between phenological and aerobiological phenomena, checking the flowering period of the allergenic species growing in different ecological stations. These studies have been further developed by analytical investigations of the phenomena. Presence-abundance of the taxonomic groups has been assessed by field surveys and represented cartographically. An accurate evaluation of the results has made it possible to draw up a series of maps in order to provide (a) a more precise knowledge of the relationship between pollen dispersal and trapping and the pollen sources, (b) useful data for the interpretation and prediction of symptoms in patients. 相似文献
13.
Jun Tanji 《Current opinion in neurobiology》1996,6(6):782-787
The supplementary motor area, although traditionally defined as a single motor area, is not viewed as including at least three different areas that can be distinguished anatomically and physiologically. The differential use of these three areas for various motor behaviors has been the subject of recent studies that are beginning to provide novel concepts of the functional differentiation of each area. 相似文献
14.
植物的间断分布格局及其形成机制是植物地理学研究的重要问题之一。本文在对中国大陆与台湾名录整理比较的基础上,对中国西南与台湾地区的植物间断分布格局及形成机制进行了分析。结果表明,两地同种型间断分布的维管植物有198种(包括变种和亚种),隶属于56科129属,其中蕨类植物86种,裸子植物3种,双子叶植物56种,单子叶植物53种;两地异种型间断分布的维管植物有22属,隶属于15科,其中蕨类植物6属,裸子植物1属,双子叶植物7属,单子叶植物兰科8属。间断分布类群以草本植物为主,主要是蕨类和兰科植物。间断分布类群在台湾地区主要分布在中部到东北部,在大陆的分布主要集中在川东–鄂西地区、川西–滇西北地区–藏东南地区和滇东南–桂西–黔西南地区。在垂直高度上,海拔1,550–2,350m是间断分布类群最集中分布的海拔范围。我们推测中国西南与台湾地区的间断分布类群有3种来源:北半球温带、中国西南和热带亚洲来源。 相似文献
15.
The efferents connections of the area postrema (AP) have been studied autoradiographically following iontophoretic injections of 3H-glycine or 3H-leucine into the area postrema. Precise control of the diffusion of the labelled amino acids injected iontophorectically into the AP was made using the technique of sectioning with a cryostat. AP projects to a great number of structures. Projections to nucleus tractus solitarius (NFS), dorsal vagal nucleus, nucleus intercalatus, nucleus praepositus hypoglossi, nucleus hypoglossal, the mesencephalic nucleus of V nerve, locus coeruleus and superior and inferior colliculi are shown bilaterally. The density of the efferents was greatest to the NFS and the LC. Corelations are suggested with functional mechanisms of cardiovascular regulation. 相似文献
16.
Solvent-accessible surface area calculations have been performed on two human telomeric quadruplex structures, the parallel crystal structure and an (3 + 1) anti-parallel structure determined by NMR methods. The differences in net ligand solvent-accessible surface area (ΔSASA) for four structurally distinct categories of small-molecule ligand have been computed, using docked structures of complexes with both types of quadruplex, as well as the relative contributions of polar and non-polar surface areas. It has been hypothesized that the surface area occupied by the ligand is a determinant of selectivity between different quadruplex topologies, where the ligand maximizes the accessible surface area by contacting all accessible atoms at one end of a quadruplex structure. This has enabled selectivity for a particular ligand to be assessed, for parallel compared an anti-parallel topology. The predictions for the ligands chosen, all of which have their quadruplex topological preferences experimentally determined and reported in the literature, are fully in accord with observation. It is suggested that this approach, which does not depend on energy functions, can be useful in the rational design of topology-specific ligands, especially in the case of polymorphic quadruplexes. 相似文献
17.
Investigations have demonstrated that the pressor effects of low-dose intravertebral angiotensin II (Ang II) in the dog are mediated by the area postrema (AP). Chronic ablation of the AP has been shown to produce both mild hypotension and blunting of the pressor effects of peripherally administered Ang II, which suggests a tonic influence by this structure on the regulation of blood pressure. These findings motivated a correlated series of neurophysiological and anatomical studies to characterize further the AP pressor pathway. The pressor response to electrical stimulation of the AP was shown to be mediated by increased central sympathetic outflow, as shown previously for the response to intravertebral Ang II, and unopposed by the central nervous system baroreflex pathways. Neuroanatomical investigations demonstrated a three-layer structure in the dog's AP, with efferent projections into the medial nucleus tractus solitarii bilaterally. These studies have provided new evidence about the functional and structural mechanisms by which the AP participates in cardiovascular regulation. 相似文献
18.
A prospective study on dynamic spirometric parameters on 195 healthy non-smoking men-workers, representing the non-smoking labor population from 16 to 40 years of age, in the Murcia Region (Spain), has been carried out. Men were selected upon two criteria: age and height. Lower normality limits, have been estimated with 95% reliability by developing regression equations for the following spirometric parameters: forced vital capacity, forced expiratory volume (timed and relative), peak flow and forced mid-expiratory flow. 相似文献
19.
Uchugonova A Duong J Zhang N König K Hoffman RM 《Journal of cellular biochemistry》2011,112(8):2046-2050
Nestin-expressing pluripotent stem cells have been found both in the bulge area (BA) as well as the dermal papilla (DP). Nestin-expressing stem cells of both the BA and DP have been previously shown to be able to form neurons and other non-follicle cell types. The nestin-expressing stem cells from the DP have been termed skin precursor or SKP cells. Both nestin-expressing DP and BA cells have been previously shown to effect repair of the injured spinal cord and peripheral nerve, with the BA being the greater and more constant source of the stem cells. The BA contains nestin-expressing stem cells throughout the hair cycle, whereas nestin-expressing dermal papillae stem cells were found in early and mid-anagen only. Our previous studies have shown that the nestin-expressing stem cells in the BA and DP have similar morphological features. The cells from both regions have a small body diameter of approximately 7 μm with long extrusions, as shown by 2-photon imaging. In the present study, using 2-photon imaging of whisker follicles from transgenic mice expressing nestin-driven green fluorescent protein (ND-GFP), we demonstrate that the BA is the source of the nestin-expressing stem cells of the hair follicle. The nestin-expressing stem cells migrate from the BA to the DP as well as into the surrounding skin tissues including the epidermis, and during wound healing, suggesting that the BA may be the source of the stem cells of the skin itself. 相似文献
20.
We studied the vegetation of the aquatic ecosystems ofLake Mikri Prespa. The lacustrine vegetationcomprises three distinct forms: floating plants,benthic hydrophytes and helophytes, which aredescribed and classified from the phytosociologicalpoint of view, as follows: (a) the vegetation of thefloating plants belong to the Lemnetea class and isrepresented by two plant communities; (b) thevegetation of the benthic hydrophytes, belongs to thePotametea class consisting of two differentcategories, namely the submersed formations and theemergent formations of the hydrophytes. Various plantcommunities were recognised in this type of vegetationand three among them are considered as the mostrepresentative; (c) the vegetation of helophytes, theprevailing life form in this wetland, belongs to thePhragmitetea class and is represented mainly by sevenwell organised plant communities. The respectivevegetation of two of the five more important wetlandsites is described.The terrestrial vegetation is composed of forestand meadow vegetation. The forest vegetation of theNational Park belongs to the class Querco-Fagetea andshows the following zonation: (a) in the vicinity ofthe lake, at the elevation of 860–1000 m, twoassociations have been found: the mixed deciduous andevergreen forests of Ostryo-Carpinion orientalis andthe evergreen forests of Ostryo-Carpinion adriaticum;(b) the deciduous oak forests surround the previouszone at the altitude of 900–1300 m with two principalassociations, namely the Quercetum frainetto and theQuercetum petraeae; (c) in the upper forest layerbetween 1200–1800 m asl, dominate beech forests of theassociation Fagion moesiacum and the less extensiveoccurrence of the mixed beech-fir stands (Ass.Abieti-Fagetum moesiacum).The zone above the tree limit is distinguished by itssubalpine character semi-shrub vegetation extendinghigher than the forest (1800–2000 m), whereas alpine meadowscover the vegetation at higheraltitudes. On the plains and in the forest clearingsexist herbaceous meadow formations of variablestructure, in parallel with the vegetation of specifichabitats, such as nitrophilous and ammophilousplants. 相似文献