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1.
池塘氮循环中各种细菌与理化因子的相关性研究   总被引:11,自引:0,他引:11  
对精养鱼池的水体及淤泥进行多次采样,用统计学分析处理,结果表明:硝化类细菌总体上与各主要理化因子的相关性较强(R>0.60),其中氨化菌主要与溶氧相关程度较高;反硝化菌主要与有效磷相关程度较高;亚硝化菌主要与氨氮负相关程度较高;硝化菌主要与亚硝酸盐相关程度较高。硝化类细菌与异养菌之间的相关性则更强,如反硝化菌与厌养菌(R=0.944,P=0.001)、拓硝化菌和好氧异养菌(R=0.832,P=0.003)皆显正相关,亚硝化菌和厌氧异养菌(R=-0.76,P=0.009)显负相关;而在硝化类细菌之间的相关程度却较弱(R<0.60),表明池塘硝化类细菌对水质具有一定的调控作用,但相互之间的依赖性不强,各自相对独立地发挥作用。  相似文献   

2.
We present the first published estimates of U. S. adult mortality risk by detailed educational degree, including advanced postsecondary degrees. We use the 1997–2002 National Health Interview Survey (NHIS) Linked Mortality Files and Cox proportional hazards models to reveal wide graded differences in mortality by educational degree. Compared to adults who have a professional degree, those with an MA are 5 percent, those with a BA are 26 percent, those with an AA are 44 percent, those with some college are 65 percent, high school graduates are 80 percent, and those with a GED or 12 or fewer years of schooling are at least 95 percent more likely to die during the follow-up period, net of sociodemographic controls. These differentials vary by gender and cohort. Advanced educational degrees are associated not only with increased workforce skill level but with a reduced risk of death.  相似文献   

3.
All species that have been described of the genera mentioned in the title are listed and their systematic position given. The species of Stilifer (with 11 species, including S. inflatus sp.n. and 5. concavus sp.n.) are parasites of starfishes. Scalenostoma (3 species) are parasites of stone corals. Thyca (with 8 species) is removed from Capulidae, and included in Eulimidae. T. hawaiiensis sp.n. is described. The species of Thyca are parasites of starfishes. The species of Mucronalia (including M. trilineata sp.n.) are probably parasites of ophiuroids and Echineulima (with 4–6 species, including E. ponderi sp.n.) are parasites of echinoids. All species are figured, their characteristics are given and their host species and distributions are listed. Keys are given to the species of each genus, except Mucronalia. The genera Stilimella Laseron and Hyperlia Pilsbry are synonymized with Scalenostoma and the genera Kiramodulus Kuroda, Granulithyca Habe and Bessomia Berry are considered subgenera of Thyca.  相似文献   

4.
In the adult palm squirrel, F. pennanti the pineal is a club shaped, elongated structure with a connective tissue capsule. It consists of various types of pinealocytes, glial cells, neurons, nerve fibres, blood vessels and connective tissue. Two types of pinealocytes could be identified by light microscopy. They are large rounded with centrally placed nucleus, and small rounded pinealocytes. They have medium sized processes stainable with Alcian blue, periodic acid Schiff and Nissl methods. The pinealocytes are not stainable with bromophenol blue. However, they are moderately stainable with PAS, Sudan black and Baker's acid hematin. Neurons are seen either singly or in groups with axonal processes. Cystic cavities often lined by cells are a normal feature of adult squirrel pineal, and the lining cells are both pinealocytes and glial cells. Often neuronal endings are seen terminating on these lining cells. PAS positive globules were also seen inside the cysts. In some squirrel pineals, fibrous cysts with an inner core of cells are also seen. Occasionally groups of lymphocytes were also encountered in the pineal. In the fetal pineal, the cells are both larger and smaller ones and arranged in a cortex and medulla pattern and no cystic cavities are seen. The third ventricle enters the base of the pineal as pineal recess.  相似文献   

5.
江西省资溪县马头山蕨类植物区系   总被引:1,自引:0,他引:1  
马头山蕨类植物区系由 3 0科 62属 1 42种组成。区系地理成份复杂 ,科属的地理成份以热带亚热带性质为主。主要的科是鳞毛蕨科 (2 5种 )、水龙骨科 (1 8种 )、金星蕨科 (1 5种 )、卷柏科 (1 1种 )、蹄盖蕨科 (1 1种 ) ,5科占总种数 5 6.3 4%。主要的属是鳞毛蕨属 (1 6种 )、卷柏属 (1 1种 )、凤尾蕨属 (8种 )、铁角蕨属 (8种 )、复叶耳蕨属 (5种 )、假瘤蕨属 (4种 )占总种数 3 6.62 %。马头山蕨类植物区系属的地理成份可分为 8个 ,主要是泛热带 (1 9属 )、热带亚洲 (7属 )、世界广布 (1 9属 )成份 ,占总属数 72 .5 8%。而种的地理成份则以亚热带山地成份为主 ,本区东亚成份突出 ,加上中国特有成份共占总种数的 66.2 1 %。显然应是东亚植物区系的一部分。掌叶假瘤蕨为江西省首次发现。  相似文献   

6.
Abstract. The subfamily Cercobarconinae is synonymized with the Trachypetinae, the constituent genera ( Trachypetus Guérin de Méneville, Megalohelcon Turner and Cercobarcon Tobias) are rediagnosed and the species are revised and redescribed. Rhamphobarcon Tobias is synonymized with Megalohelcon Turner, R.mosaicus Tobias is synonymized with M.torresensis Turner, M.uptoni Tobias is synonymized with M.ichneumonoides Tobias, and four species are newly described: M.mouldsi, C.bilobatus, C.grossi and C.niger. Relationships within the subfamily are discussed, as are those of the Trachypetinae to other braconid subfamilies. Comments on the biology and distribution of species are provided, along with an illustrated key to genera and species.  相似文献   

7.
Lipid-protein interactions in membranes are dynamic, and consequently are well studied by magnetic resonance spectroscopy. More recently, lipids associated with integral membrane proteins have been resolved in crystals by X-ray diffraction, mostly at cryogenic temperatures. The conformation and chain ordering of lipids in crystals of integral proteins are reviewed here and are compared and contrasted with results from magnetic resonance and with the crystal structures of phospholipid bilayers. Various aspects of spin-label magnetic resonance studies on lipid interactions with single integral proteins are also reviewed: specificity for phosphatidylcholine, competition with local anaesthetics, oligomer formation of single transmembrane helices, and protein-linked lipid chains. Finally, the interactions between integral proteins and peripheral or lipid-linked proteins, as reflected by the lipid-protein interactions in double reconstitutions, are considered.  相似文献   

8.
Alkamides are natural products formed by connecting straight-chain, mostly unsaturated, aliphatic acids with various amines by an amide linkage. More than 300 derivatives are known from eight plant families consisting of various combinations of 200 acids with 23 amines. Apart from a few saturated derivatives alkamides with unsaturated acid parts are grouped into compounds with purely olefinic patterns and those with olefinic and acetylenic linkages. Derived from C18 oleic acid the acid parts are modified either by chain elongations to C28 or by oxidative shortenings to C4 acid residues. Substrate and regiospecific desaturases and acetylenases are responsible for their characteristic patterns of unsaturation. Amine parts are derived from various amino acids by decarboxylation. Beside the widespread isobutylamines alkamides with six- and five-membered ring amines and those with phenylalanine derived amines are characteristic for the Asteraceae and Piperaceae while benzylamines are restricted to the Brassicaceae. Within the Asteraceae 2-methylbutylamine distinguishes the tribe Heliantheae from Anthemideae characterized by ring amines. Alkamides with elongated olefinic acid parts are mainly found in Piperaceae and Brassicaceae while acetylenic acid parts are typical for Asteraceae. A wide variety of biological activities ranges from the characteristic pungent/tingling property and high insecticidal toxicity to significant antifungal, antibacterial, antiprotozoal, molluscicidal, cercaricidal, and acaricidal activity. They also act as plant growth-promoting substances. Position and stereochemistry of the double bonds are essential for the different qualities of the pungent taste. Medically alkamides possess anti-inflammatory and analgesic properties and are responsible for immuno-modulatory and cannabinomimetic effects.  相似文献   

9.
Gel filtration with 1% agarose (Bio-Gel A-150m) separates polyribosomes bound to microsomal membranes from 'free' polyribosomes when these fractions are prepared by standard centrifugal techniques. However, when polyribosomes contained in an unfractionated postmitochondrial supernatant are run on an identical column, over 90% of the total polyribosomes are present as aggregates, designated 'membrane-cytomatrix', which are eluted in the column void volume. Polyribosomes are not released from these aggregates on removal of microsomal phospholipids by treatment of postmitochondrial supernatant with 1% Triton X-100, a neutral detergent. The aggregates are disrupted by the usual ultracentrifugation techniques used in subcellular fractionation. After treatment of membrane-cytomatrix with Triton X-100 to remove phospholipids and membrane proteins, 58% of the polyribosomes still remain associated with protein-containing complexes in the form of a cytomatrix and are not 'free'. Preparations of both membrane-cytomatrix and cytomatrix are capable of sustained protein synthesis. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis revealed that the cytoskeletal proteins actin and myosin are present in the cytomatrix. Incubation of cytomatrix preparations with the actin-depolymerizing agent deoxyribonuclease I caused release of the polyribosomes. Polyribosome release by deoxyribonuclease I was prevented by prior incubation with phalloidin, which is known to stabilize F-actin. Thus polyribosomes are associated with cytoskeletal elements in rat liver, and this association is dependent on polymeric forms of actin.  相似文献   

10.
Histological and electronmicroscopical studies have shown that the subcuticular tissue associated with the porose areas of femaleRhipicephalus evertsi evertsi consists of paired multicellular, alveolar and lobularly arranged glands. At least two types of cells are clearly distinguishable, according with their location. Proximally, in direct association with the pores, cells with small and long nuclei are present. These cells are aligned along large, elongated lumina containing numerous microvilli and extend deep into the cuticular pores. They are separated from the extraintegumental space by cuticular valves. The distal gland sections are characterized by cells with large nuclei which are mostly arranged in the form of rosettes. These cells, which function as secretory cells, contain many mitochondria, smooth and rough endoplasmic reticulum and membrane-lined vesicles. The glands are always present in female ticks and their dorso-ventral extension increases continuously with feeding, reaching a maximum depth during oviposition.  相似文献   

11.
用紫外线照射四季豆根瘤菌(R.Phaseoli)、豌豆根瘤菌(R.Leguminosarm)和花生根瘤菌(R.Peanut),然后观察其形态特征,并将不同形态特征菌落的菌株接种于不同pH值YEM培养基和不同NaCl浓度的YEM培养基上培养。结果表明,突变株的抗酸碱性和抗盐性随根瘤菌不同而异,并与其菌落形态有关。  相似文献   

12.
C. H. Fry 《Ibis》1969,111(1):23-29
The manner in which bee-eaters cope with the stinging honey-bees which comprise their principal food was investigated by aviary studies of Merops bullocki. Worker Apis are de-venomed by an innate sequence of beating the insect and rubbing its abdomen against the perch. Treatment improves with experience. Drone bees are distinguished by the birds from workers but are not instantly recognised as non-venomous; they are subjected to low intensity rubbing combined with non-venomous prey treatment concomitant with their size. Non-Hymenoptera, including some insects which superficially resemble bees, are recognised as non-venomous and are not rubbed, but are beaten until immobilized. Bee-eaters appear to have partial immunity to venom.  相似文献   

13.
红褐斑腿蝗血细胞的形态与分类   总被引:1,自引:0,他引:1  
王世贵  周志军  郑哲民 《昆虫知识》2007,44(2):241-244,F0004
利用光学显微镜和显微数码拍照系统,对红褐斑腿蝗Catantops pinguis(Stal)血细胞的形态进行观察和分类。结果在红褐斑腿蝗血淋巴中观察到5种血细胞,分别是原血胞、浆血胞、粒血胞、珠血胞和囊血胞。原血胞为小型圆形细胞,边缘圆滑、清晰,核质比例很大。粒血胞多为中型,形状不规则,边缘凹突不平,内含较大的异质性溶酶体颗粒。浆血胞多为中型,刚离体时形状较规则,常呈圆形、卵圆形。浆血胞内缺乏大的颗粒,细胞核大而圆形,细胞质内具许多小型颗粒状物质。浆血胞离体后形状变化较多,常发展出伪足,呈丝状、短芒状、钩状或片状伪足。珠血胞多为大、中型,外形大体呈圆形,但边缘由于大小不等的珠形内含物突出,呈花瓣状。囊血胞多为中型,圆形或椭圆形,细胞质内具有大小不一的带有折光性的颗粒或块状物,细胞边缘比较光滑。  相似文献   

14.
The various glands of rhesus monkey eyelids and human eyelids are similar. Numerous modified sebaceous glands are located along the tarsus. These conform with the meibomian glands, while typical sebaceous glands associated with the hair follicles of the lashes are consistent with the glands of Zeis. Lobules of accessory lacrimal tissue, corresponding to the glands of Krause and Wolfring, are located in the conjunctiva of the fornix and along the orbital border of the tarsal plate. Goblet cells are plentiful in the mucosa of the palpebral and bulbar conjunctiva, and along the lid margin are the sweat glands of Moll.  相似文献   

15.
Three physiological inhibitors of blood coagulation - alpha-2-macroglobulin, alpha-1-antitrypsin, and C-1-inhibitor of complement - are dealt with in a brief survey. The point is that these are proteins of the organism with a defence character which are also able to inhibit an extraordinarily broad spectrum of proteases. Some recent findings about their molecular structure, manner of response, and inhibitory spectrum are represented. Comparisons are made to corresponding proteins in mammals, in alpha-2-macroglobulin and even in lower vertebrates. Moreover, the inherited deficiency of these three inhibitors are represented with respect to human diseases and changes of their blood level in the course of various diseases are referred to.  相似文献   

16.
17.
The interaction of DAPI and propidium with RNA (polyA.polyU) and corresponding DNA (polydA.polydT) sequences has been compared by spectroscopic, kinetic, viscometric, Tm, and molecular modeling methods. Spectral changes of propidium are similar on binding to the AT and AU sequences but are significantly different for binding of DAPI. Spectral changes for DAPI with the DNA sequence are consistent with the expected groove-binding mode. All spectral changes for complexes of propidium with RNA and DNA and for DAPI with RNA, however, are consistent with an intercalation binding mode. When complexed with RNA, for example, DAPI aromatic protons signals shift significantly upfield, and the DAPI UV-visible spectrum shows significantly larger changes than when complexed with DNA. Slopes of log kd (dissociation rate constants) versus-log [Na+] plots are similar for complexes of propidium with RNA and DNA and for the DAPI-RNA complex and are in the range expected for an intercalation complex. The slope for the DAPI-DNA complex, however, is much larger and is in the range expected for a groove-binding complex. Association kinetics results also support an intercalation binding mode for the DAPI-RNA complex. The viscosity of polyA.polyU solutions increases significantly on addition of both propidium and DAPI, again in agreement with an intercalation binding mode for both molecules with RNA. Molecular modeling studies completely support the experimental findings and indicate that DAPI forms a very favorable intercalation complex with RNA. DAPI also forms a very stable complex in the minor groove of AT sequences of DNA, but the stabilizing interactions are considerably reduced in the wide, shallow minor groove of RNA. Modeling studies,thus,indicate that DAPI interaction energetics are more favorable for minor-groove binding in AT sequences but are more favorable for interaction in RNA.  相似文献   

18.
Lymphocytes responding in a "secondary" MLC-CML system, after in vitro sensitization, apparently fall into two classes with regard to their Lyt phenotype. First, are the cells that form the majority of the proliferating cells after restimulation with either I or K + I differences, which are Lyt 1-2, and second, are Tc that are Lyt 1-2+. The Lyt 1-2- proliferating cells are not cytotoxic and are lysed by treatment with anti-Thy 1.2 serum in the presence of C.  相似文献   

19.
20.
This paper deals with chromosomal numbers and morphology of 10 species of Aconitum in China. According to the basic number of the genus (x=8), these species can be referred to diploid, tetraploid, hexaploid and octoploid. Correlation is found between chromosomal numbers, sizes and structures. The perennial species with a rhizome are mostly diploid, with chromosomes larger than those in the biennial species with a tuber, and their chromosome pairs 3-7 are mostly subterminal ones, whereas most biennial species are polyploid, and their chromosome pairs 3-7 are almost submetacentric. The evolutionary trends of chromosome from diploid to polyploid, large to small, st to sm are considered possible. The data are agreed with the idea that rhizomal species are more primitive than tuberous ones. The existence of two types of karyotypes in these 10 species is a further support of taxonomic division of two subgenera, subgen. Paraconitum and subgen. Aconitum. In addition, some species are taxonomically discussed.  相似文献   

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