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1.
粤东的红树林   总被引:4,自引:0,他引:4       下载免费PDF全文
Rhizophora stylosa, Heritiera littoralis and Lumnitzera racemosa are the new records of geographical distribution of the mangrove floristic composition in the coast district of east Guangdong. In the mangrove of this coast district, there are 13 families, 20 genera, 20 species, making up 24% of the total species of mangrove of the world, ess than Hainan Island but almost equal to west Guangdong. It shows the physiognomy and structure of shrubland and forest. According to the floristiccomposition, physiognomy, structure and characteristics of habitat, it may be divided into two types: beach-mangrove and coast-semi-mangrove and seven formations.The distribution of angrove in the coast of east Guangdong indicates the situation of the mangrove of this district in the geographical distribution of mangrove in the world and the tropical character of vegetation and the transition of vegetation from tropics to subtropics in this district.  相似文献   

2.
In this paper, we focus on investigating the stochastic stability and the regime transition between the endangered state and the boom state for a time-delayed insect growth system driven by correlated external and internal noises. By use of the Fokker Planck equation, the method of small time delay approximation and the fast descent method, we explore in detail the joint action of noise terms and time delay on the mean reproduction and depression time for the insect population. Our investigations indicate that the pseudo-resonance phenomenon of the mean first-passage time (MFPT) occurs because of the impact of different noises and time delay. Through the numerical calculation, it is discovered that multiplicative noise can speed up the shift of the insect population from the boom state to the endangered one, while the noise correlation and time delay can propel the insect system to evolve from the endangered state to the boom state and improve the biological stability. In addition, the impact of the additive noise on the stability of the biological system depends on the positive and negative situation of the noise correlation. On the other hand, during the process of suppressing the insect explosion, it is beneficial to the pest control to amplify the association noise strength and weaken the intensities of the multiplicative, additive noises and time delay. However, during the process of eliminating the pests, it can produce nice effect on the disinsection to increase time delay, the intensities of multiplicative and additive noises and weaken the strength of noise correlation.  相似文献   

3.
Prototype Design and Experimental Study on Locust Air-Posture Righting   总被引:1,自引:0,他引:1  
Locust has the capacity to maintain a righting posture and glide through attitude adjustment after leaping. A prototype inspired by the dynamic mechanism of attitude adjustment of locusts was developed. The prototype consists of a pair of wings driven by a four-bar mechanism, and a 2 Degree of Freedom (DOF) tail to imitate the movement of the locust abdomen. The power source, microcontroller, wireless data transmission module, and attitude sensors are contained in the fuselage. Experiments imitating the flight of locust were conducted to determine the mechanism of locust Subsequent Attitude Adjustment (SAA). The tethered prototype was driven by the movement of the tail and the flapping of the wings. Results show that the pitch and yaw of the tail, and the asymmetric action of the flapping wings significantly influence the posture of the prototype. These findings suggest that both the wiggling abdomen and flapping wings contribute to the locust SAA in the air. This research lays the groundwork and technical support for the probable design and development of practical jumping robots with attitude adjustment function.  相似文献   

4.
Although monocytes and macrophages are key mediators of the innate immune system, the focus has largely been on the role of the adaptive immune system in the context of human immunodeficiency virus(HIV) infection. Thus more attention and research work regarding the innate immune system—especially the role of monocytes and macrophages during early HIV-1 infection—is required. Blood monocytes and tissue macrophages are both susceptible targets of HIV-1 infection,and the early host response can determine whether the nature of the infection becomes pathogenic or not. For example,monocytes and macrophages can contribute to the HIV reservoir and viral persistence, and influence the initiation/extension of immune activation and chronic inflammation. Here the expansion of monocyte subsets(classical, intermediate and non-classical) provide an increased understanding of the crucial role they play in terms of chronic inflammation and also by increasing the risk of coagulation during HIV-1 infection. This review discusses the role of monocytes and macrophages during HIV-1 pathogenesis, starting from the early response to late dysregulation that occurs as a result of persistent immune activation and chronic inflammation. Such changes are also linked to downstream targets such as increased coagulation and the onset of cardiovascular diseases.  相似文献   

5.
The Kangchenjunga Landscape (KL) in the Eastern Himalayas is a transboundary complex shared by Bhutan, India, and Nepal. It forms a part of the ‘Himalayan Biodiversity Hotspot’ and is one of the biologically richest landscapes in the Eastern Himalayas. In this paper, we use secondary information to review and consolidate the knowledge on the flora of the KL. We reviewed 215 journal articles, analysed the history of publications on the flora of the KL, their publication pattern in terms of temporal and spatial distribution and key research areas. Our review shows that the landscape has a long history of botanical research that dates back to the 1840s and progressed remarkably after the 1980s. Most of the studies have been carried out in India, followed by Nepal and Bhutan. The majority of these have been vegetation surveys, followed by research on ethnobotanical aspects and Non-Timber Forest Products (NTFPs). This paper describes the forest types and characteristic species of the KL and details the species richness, diversity and dominant families of seed plants. A total of 5198 species of seed plants belonging to 1548 genera and 216 families have been recorded from the landscape, including 3860 dicots, 1315 monocots and 23 gymnosperms. Among families, Orchidaceae is the most diversely represented family in terms of species richness. This paper also draws attention to the threatened and endemic flora of the KL, including 44 species that are threatened at national and global level and 182 species that are endemic. Finally, the paper reviews the major challenges facing the KL, the conservation efforts and practices that are currently in place and recommends systematic and comprehensive floral surveys, particularly long-term data collection and monitoring and transboundary collaboration, to address the existing knowledge gaps on floral diversity of the KL.  相似文献   

6.
A prospective randomized trial was used to determine iron concentrations in intestinal cancer tissue and colorectum polyps. We investigated the possible difference between the concentrations of iron, ferritin, albumin, and hemoglobin in the serum of patients with colorectal cancer and polyps. We also determined the relationship between the iron and ferritin levels in cancer tissue, the localization of neoplasms, and the stage of their development. The study comprises 67 patients with colorectum cancer and 42 patients with colon and rectum polyps. The metal was determined by using the total-reflection X-ray fluorescence (TRXRF) method. The mean concentration of iron in colorectal cancer equaled 46.1 μg/g of the tissue and was higher than in the case of polyps (43.2 μg/g). The mean serum iron level in patients with colorectal cancer was statistically lower than in the serum of patients with polyp and in the control group (54.5, 91.3, and 108.0 μg/g, respectively). The determined average concentration of ferritin in the serum of patients with colorectal cancer equaled 60.4 μg/g and was statistically lower than the level of this enzyme in the serum of patients with polyps (85.2 μg/g) and in the control group (102.0 μg/g). There was no difference between the serum albumin and hemoglobin concentrations in patients with colorectal cancer, polyps, and the control. There was no difference in the levels of iron and ferritin depending on the location of the neoplasm and the stage of its development. Also, there was no difference between the concentrations of iron in the cancer tissue of malignant and benign tumors after taking into consideration sex and age of patients. During the examination we determined significantly higher concentrations of iron in the cancer tissue and not in the polyp. The low levels of iron in the serum of patients with malignant tumor may increase colorectal cancer risk.  相似文献   

7.
The seed embryos of lsatis indigotica Fort were exposed to He-Ne laser (5.23 mW/mm^2, radiated for 5 min) and microwave ( 1.26 mW/mm^2, radiated for 8 s) irradiation to determine the effects of microwave and He-Ne laser pretreatment on enzyme activities, and biophoton emission of cotyledon. Then: (i) changes in the activities of enzymes in L indigotica cotyledon (such as amylase, transaminase, and proteinase) were measured to investigate the effects of He-Ne laser and microwave pretreatment; and (ii) biophoton emission was measured to determine the speed of cell division and metabolism. Results from these experiments indicated that: (i) the activities of amylase, transaminase, and proteinase of the cotyledon pretreated by HeNe laser and microwave were significantly increased; and (ii) the intensity of biophoton emission was enhanced significantly by He-Ne laser and microwave irradiation. These changes suggest that He-Ne laser and microwave pretreatment can improve the inner energy of seeds, lead to an enhancement of cotyledon enzymes, and speed up the metabolism of the cell, resulting in significantly increased biophoton emission. Moreover, the mechanism of action of the effects of laser and microwave radiation on the microcalorimetric parameters, enzyme activities, and biophoton emission of seeds is discussed on the basis of the results obtained.  相似文献   

8.
In this work, the concentrations, temporal and spatial distributions and the relationship between biogenic silica (BSi) and primary productivity are discussed on the basis of the geochemistry character of BSi in the water–sediment system of the Wuliangsuhai Lake and Daihai Lake. The results show that the average concentrations of SiO32- and BSi are 3.0 mg/L and 3.5 mg/g in the overlying water and sediments from the Wuliangsuhai Lake, respectively, while they are 1.0 mg/L and 7.5 mg/g, respectively, in the Daihai Lake. It is the uptake and assimilation of diatom phytoplankton which results in the significant difference of the SiO32- concentrations between the two lakes, and the inputs of surface runoff is one of the important factors in impacting the spatial distributions of SiO32- in the overlying water. The spatial distributions of BSi suggest the Si source of the two lakes and indicate the differences of eutrophication types and ancient primary producer between the two lakes. The eutrophication precesses and ancient primary productivity of diatom phytoplankton are reconstructed by applying the geochemistry information of BSi archived in the vertical concentration profiles in the two lake sediments. The geochemistry information of BSi well responds to the paleoenvironment and paleoclimate of the Daihai drainage basin indicating silicate limitation of primary productivity by diatoms phytoplankton in the Daihai Lake.  相似文献   

9.
Virology is a branch of biological science dealing with the study of viruses, and medical virology focuses on the study and control of diseases due to viruses that is of medical importance. The development of medical virology in Malaysia has its beginning in the Institute for Medical Research (IMR), following the establishment of the Division of Medical Zoology and Virus Research in the institute on 23 March 1953. The second institution in the country to establish diagnostic and research work in medical virology was Department of Medical Microbiology, Faculty of Medicine, University Malaya. This was followed by University Kebangsaan Malaysia, University Sains Malaysia and University of Sarawak Malaysia. The National Public Health Laboratory (NPHL) is the latest institution to establish a laboratory in 2003 for virus isolation and services to support country surveillance and outbreak investigation of infectious diseases due to viruses. In the field of medical virology, Malaysia contributed substantially in the areas of virus diagnostic services, development and research ranging from survey and documentation on the existence and prevalence of viruses causing diseases in Malaysia, clinical presentation and epidemiological features of virus diseases, evaluation of new diagnostic tests to pathogenesis of viral diseases. Malaysia contributed to the discoveries of at least 12 new viruses in the world. ASEAN plus Three (China, Japan, Republic of Korea) Emerging Infectious Programme was established to overcome the challenges and impact of emerging and re-emerging infectious diseases in this region. Malaysia as the co-ordinator of the laboratory component of the programme, contributed to strengthen the regional laboratory capability, capacity, laboratory-based surveillance and networking. The future of medical virology in Malaysia in terms of integration of diagnostic, reference and research to support the country's need will be enhanced and strengthened with the on-going development of the National Centre fo  相似文献   

10.
Anatomical, histochemical and phytochemical methods were used to investigate the structure, localization and dynamic changes of total saponin and senegenin of vegetative organs in Polygala tenuifolia Willd. Histochemical localization results showed that saponin accumulated mainly in parenchyma cells of vegetative organs. The phytochemical results also showed that the saponin accumulated in the vegetative organs of P. tenuifolia, with higher content in roots and lower content in the aerial parts that included stems and leaves. The saponin content and dry weight of the vegetative organs of P. tenuifolia had dynamic variance at the developmental stages and all reached the highest level in the post-fruit period. Hence, the roots and aerial parts should be gathered in August to make full use of the plant. As the root is the main medicinal organ of P. tenuifolia, the content of total saponin and senegenin of different aged and different parts of the root were determined. The content of total saponin and senegenin exhibited a sustained decreasing trend with increasing root age; therefore, the annual roots had high quality. The content of total saponin and senegenin in different parts of the root showed obvious variation. The content in the "skin areas" was much higher than that of xylem. The results offer a theoretical basis for determining the appropriate harvesting stage and a reasonable harvest of P. tenuifolia.  相似文献   

11.
Biophysicochemical approaches to the solution of nanotechnology problems associated with the design of functional biomimetic nanosystems, hybrid and composite nanobiomaterials and study of their structure-function relationships. The results of studies concerned with physicochemical mechanisms of the formation of organized biomimetic nanostructures and bioinorganic nanomaterials in systems involving a bulky liquid phase and the interface (gas-liquid, solid-liquid, liquid-liquid)during the synthesis and structure formation with the participation of the components of colloid systems, inorganic nanoparticles of various composition and clusters of metals, surfactants, polyelectrolytes and their complexes are discussed. In the development of the methods for the formation of composite bioinorganic nanosystems containing inorganic nanocomponents, two major approaches were used: adsorption and incorporation into the biomolecular matrix or colloid system of presynthesized inorganic nanoparticles, as well as the synthesis of the inorganic nanophase immediately in the biomolecular system. The methods of obtaining biomaterials and nanosystems are based on the principles of biomimetics, biomineralization, self-assembly and self-organization, combination and integration of a number of synthetic and physicochemical methods (physical and chemical adsorption, Langmuir technique, the formation of polycomplexes, chemical linking, competitive interactions, and substitution of ligands in supramolecular and coordination complexes) and nanocomponents of different nature. In particular, a novel approach to the preparation of highly organized nanofilm materials was developed, which is based on the effect of self-assembly and self-organization of colloid nanoparticles during the formation of their complexes with polyfunctional biogenic ligands in the volume of the liquid phase in the absence of any surfaces and interfaces. The physical and chemical factors responsible for the formation of structurally ordered biomolecular and composite nanosystems including nano-sized components of different nature and the possibilities to control the composition, structure, and properties of resulting nanomaterials and nanosystems are discussed. The experimental methods and approaches developed may be useful in studies of structure-property relationships and basic mechanisms of structural organization and transformation at the nanoscales level in biological, artificial, and hybrid nanosystems. The problems of practical application of the synthetic methods and the corresponding nanomaterials are discussed.  相似文献   

12.
The authors present the results of examination of tremor (hand and trunk) of the amplitude of H- and T-reflexes and of the H-reflex inhibition during the contraction of antagonistic muscles and of facilitattion of T- and H-reflexes during the Yendrassik maneuvre in 33 children with hyperfunction of the thyroid gland and 20 normal subjects. It was established that the amplitude of tremor was greater and the frequency was less in these patients than in normal subjects; the amplitude of the H- and T-reflexes was enhanced, and the intensity of reciprocal inhibition of the soleus muscle motor neurons was less in the patients. Comparison of the amplitude of the T- and H-reflexes indicated that against the background of the Yendrassik maneuvre facilitation of the T-reflex was less intense and facilitation of the H-reflex was more intense than in normal subjects. The authors supposed that the enhanced tremor in the patients was due to the motor neurons pool depolarization, to decrease the efficacy of reciprocal inhibition and to diminished suprasegmental influences spread to the gamma-motor neurons.  相似文献   

13.
为探究低温层积过程中桃儿七种子细胞壁代谢及种皮超微结构与休眠解除的内在联系,该研究通过低温层积解除桃儿七种子休眠,分析休眠解除过程中种子不同部位细胞壁组分及相关代谢酶的变化,同时利用扫描电镜对种皮的超微结构进行观察。结果表明,(1)桃儿七种皮主要由角质层、栅状石细胞层及海绵组织层3层构成,在层积过程中,种皮内部的海绵组织逐步疏松膨胀,种皮表面破损加剧;(2)种子不同部位的细胞壁组分具有明显差异,整个层积过程中,种胚、种皮和胚乳中的纤维素含量均在层积中期(45 d和60 d)降至最低,3个部位的纤维素酶活性在层积中期对应升高;种胚和种皮内的半纤维素含量均在层积中期显著下降,种皮中甘露聚糖酶活性和木糖苷酶活性在层积中期时相应达到最大;3个部位的果胶含量均在层积后期(75 d和90 d)时显著下降,而种皮和胚乳中多聚半乳糖醛缩酶活性也在层积后期相应升高;(3)种胚和胚乳内过氧化物酶活性在层积75 d和90 d时明显下降,而SOD活性在此时显著上升。(4)种子不同部位3种木质素单体的组成比例具有明显区别,同时3种木质素单体含量均随层积时间的延长而显著降低,且胚乳和种皮中的S-木质素含量对种子萌发存在显著的负向影响关系。研究认为,在低温层积过程中,桃儿七种子内细胞壁组分纤维素、半纤维素及木质素的逐步酶解,活性氧作用下的细胞壁松弛以及海绵组织层的疏松膨胀和种皮的破裂,破坏了细胞壁的刚性结构,促使种子机械束缚力降低,吸水性能提高、胚根生长能力增强,最终导致其休眠解除。  相似文献   

14.
The summarized results of original studies, carried out in 1988-2003 by scientists of the Gamaleya Research Institute of Epidemiology and Microbiology, are discussed. The part dealing with the regularity and mechanisms of the circulation of pathogenic bacteria in the biocenosis of soil and water reservoirs includes the following subjects: population and intracellular interactions with protozoa; the evaluation of different representatives of hydrobios as hosts and the transmission along trophic biocenotic chains; the effect of algae and their metabolic products on bacterial populations; the possibility of the colonization of higher plants from the soil and the subsequent infection of rodents; the variability and clonal structure of bacterial population in its interaction with protozoa and plants; the chain of Yersinia circulation in agrocenosis. The part dealing with the mechanisms of the prolonged reservation of causative agents includes such subjects as the reversible transition of bacteria into the latent (uncultivable) state in soils and water reservoirs, as well as the biological inductors of this process; the prolonged preservation of latent bacteria in the cysts of protozoa and blue-green algae; the indication of causative agents in the natural foci of plague and pseudotuberculosis. On the basis of the original investigations and the data of literature new theoretical review in the field of the natural foci and the epidemiology of sapronotic infections have been formulated.  相似文献   

15.
孔令桥  郑华  欧阳志云 《生态学报》2019,39(23):8903-8910
山水林田湖草系统保护与修复的重要目标是维护和提升区域生态系统服务。基于山水林田湖草生命共同体理念,以维护和提升人类福祉所需的重要生态系统服务为目标,提出生态系统服务视角下的山水林田湖草系统治理框架,以实现流域生态系统整体保护、质量提升和格局优化。基于该框架,以洞庭湖流域为例,通过流域生态系统格局、生态系统质量状况分析、流域生态系统服务重要性评估和生态问题识别,构建流域生态安全格局,为实现可持续的山水林田湖草生命共同体提出系统保护与修复布局建议。通过洞庭湖流域的分析案例为流域山水林田湖草生态保护与修复重要区域的识别提供了可借鉴的指标和定量分析方法,为流域尺度构建生态安全格局、实现山水林田湖草系统保护和修复提供思路和途径。  相似文献   

16.
Morita and Perkins' method was applied to the study of the stage of ingestion and destruction of an antigen (sheep erythrocytes) in the macrophages of peritoneal exudate of rabbits and rats and in the microphages of rabbit pleural exudate. Ingestion and intracellular destruction of the antigen were accompanied by intensified respiration and glycolysis of phagocytes. Respiration of the three types of phagocytes at two stages of phagocytosis and also the digestive capacity of microphages proved to be sensitive to cyanide and colchicine. The latter failed to influence the ingestion of the antigen by the three types of phagocytes and its digestion by macrophages. The differences in the metabolism routes of macro- and microphages in intracellular destruction of the antigen was postulated. An intensification of the phagocytic activity after the immunization was characteristic of rabbit and rat macrophages.  相似文献   

17.
化学除草剂对农田生物群落的影响   总被引:39,自引:0,他引:39  
从直接作用和间接作用两个方面,在个体、种群和群落3个水平上综述了化学除草剂对农田植物、动物和微生物群落的影响,并提出了今后需要加强研究的几个问题(1)残留在作物和杂草植株内的除草剂及其代谢产物通过食物链和生物富集作用对农田动物群落各级消费者造成的影响;(2)非作物生境使用化学除草剂对毗邻作物生境天敌群落的影响,以及作物生境使用除草剂对邻近非作物生境天敌群落的影响;(3)由除草剂长期使用引起的杂草群落演替、多样性下降、地表覆盖物和地下生物量减少对土壤动物和微生物群落的物种组成、分布、丰富度及其生态功能的影响;(4)化学除草剂与杀虫剂和化肥等其他农用化学品对农田生物群落的联合作用。  相似文献   

18.
口唇部是主要的面部形态区域之一,具有重要的生理功能。嘴唇保护口腔免受外部物质的渗透,维持口腔内部的湿度和温度,帮助咀嚼,同时也是外科美容整形手术中的主要部位之一,且在法医物证研究中唇纹也具有重要的鉴别价值。目前关于口唇部形态的研究主要包括以下几个方面:口唇部形态变异的性别、年龄、族群差异;影响口唇部形态变异的因素,如遗传基因、饮食结构、牙齿及颌骨形态和呼吸方式等;口唇部形态研究在医学、个人身份识别及法医刑侦领域的相关应用等。国内口唇部形态研究相对较少,尤其缺乏较为系统的口唇部形态生长发育及变异研究。本文通过梳理和归纳国内外相关文献的研究数据和结论,对口唇部形态相关研究作简要概述,并对国内口唇部生长发育及形态变异研究作了简要回顾和展望。  相似文献   

19.
S F Amakiri 《Acta anatomica》1979,103(4):434-444
Various histochemical and histological techniques were used to study the melanin and dopa-positive cell distribution in the skin of some tropical and temperate breeds of cattle in Nigeria. Melanin pigments were concentrated in the basal and lower spinous layers of the epidermis and in the hair cortex, follicle sheaths and papillae of the various breeds. In the White Fulani and N'Dama breeds, melanin pigments were however found in all layers of the epidermis. Dopa-positive cells (melanocytes) were observed in the epidermis, dermis and hair follicles; the distribution pattern varied among breeds, being copiously disposed in the basal epidermis and papillary dermis in the White Fulani and Muturu and, except in areas of thick epidermal ridges, scanty in the epidermis and dermis of the Friesian and N'Dama. Mast cell distribution pattern in the various breeds was similar to that of the dopa-positive cells. Peroxidase-positive cells were present in the basal epidermis and upper dermis of the Muturu, widespread in the subepidermal layer of the N'Dama and very scanty in the dermis of the White Fulani and Friesian. Acid phosphatase activity was intense in the granular layer of the Muturu and N'Dama breeds and also in the papillary dermis and hair follicles, whereas alkaline phosphatase-positive dendritic cells, and 'clear' cells were also observed in the basal and upper epidermis.  相似文献   

20.
Data were obtained on 1039 recoveries of embryos from beef cows of four breeds at two locations, in clinic and on farm. General linear models procedures were utilized to determine the effects of breed, location, age of donor, dosage of follicle stimulating hormone (FSH) and the interaction of age and FSH on the following dependent variables: 1) the mean number of ova (unfertilized oocytes and embryos) recovered; 2) the mean number and percentage of embryos (fertilized; live and dead) recovered; and 3) the mean number and percentage of transferable embryos recovered. The interaction of age of donor and dosage of FSH with breed and location prevented the pooling of data over breed and location. The mean number of ova recovered was affected by age of the donor (Charolais-in clinic), or the interaction between age of donor and dosage of FSH (Polled Hereford-in clinic and -on farm and Simmental -on farm). The mean number of embryos was affected by age of donor (Polled Hereford-in clinic), dosage of FSH (Simmental-in clinic) or their interaction (Angus-on farm). The mean number of transferable embryos was affected by age of donor (Polled Hereford-in clinic and -on farm, Simmental-in clinic and Angus-on farm). General linear models procedures were utilized to determine the effects of the embryo (stage of development and quality) and the recipient (synchrony with the donor) on the rate of pregnancy. Rate of pregnancy varied with embryo quality score and synchrony of the recipient and the embryo. In conclusion, the superovulatory response was found to be highly breed-specific, and most of the variability in embryos produced was attributed to the number of ova recovered. However, the number of ova, embryos and transferable embryos recovered was further influenced by age of the donor, dosage of FSH or their interaction.  相似文献   

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