首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Cao Rui 《西北植物学报》2007,27(9):1800-1800
Tetraena mongolica Maxim. is the only member of the genus Tetraena that belongs to the family Zy-gophyllaceae. It is characterized by the following features: small deciduous shrubs, 30-50 cm tall, much branched;leaves paripinnate, opposite on current year branches, and fascicled on old branches; leaflets 2,  相似文献   

2.
Cao Rui 《西北植物学报》2007,27(8):1689-1689
Tetraena mongolica Maxim. is the only member of the genus Tetraena that belongs to the family Zygophyllaceae. It is characterized by the following features: small deciduous shrubs, 30-50 cm tall, much branched;leaves paripinnate,opposite on current year branches,and fascicled on old branches; leaflets 2,  相似文献   

3.
Tetraena mongolicaMaxi m.is the only member of the genusTetraenathat belongs to the family Zy-gophyllaceae.It is characterized by the following features:small deciduous shrubs,30~50 cmtall,muchbranched;leaves paripinnate,opposite on current year branches,…  相似文献   

4.
Tetraena mongolica Maxim.is the only member of the genusTetraenathat belongs to the family Zy-gophyllaceae.It is characterized by the following features:small deciduous shrubs,30~50 cmtall,muchbranched;leaves paripinnate,opposite on current year branches,and fascicled on old branches;leaflets 2,sessile,on an extremely short leaf rachis,oblanceolate,5~7 mmlong,2~3 mm broad,entire,densely cov-ered with appressed T-shaped hairs,apex acute;flowers bisexual,solitary or 1~2 on a short shoot;sepals4…  相似文献   

5.
Emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is a major stem borer of ash (Fraxinus spp.). It is univoltine in Tianjin, while it is semivoltine in Heilongjiang Province, and both univoltine and semivoltine in Changchun, Jilin Province, where the majority is univoltine. The longevity of emerald ash borer adults is 17.2 ± 4.6 days (n = 45), eggs 9.0 5:1.1 days (n = 103), univoltine larvae 308 days, semivoltine larvae 673 days, and pupae 61.2 ± 1.6 days (n = 45). It takes about 100 days from the time larvae bore into the phloem to when they complete the pupal cell. In a 10-year-old velvet ash (Fraxinus velutina Tort.) plantation in Tianjin, emerald ash borer preferred to oviposit on the regions of boles from 50-150 cm above ground, accounting for 76.7% of the total girdling. Girdling on the south side of the tree boles accounted for 43.40% of the total girdling. The emerald ash borer population density is higher at the edge of the plantation compared with the center.  相似文献   

6.
An amphioxus full-length cDNA, AmphiCalbin, encoding a novel EF-hand calcium-binding protein (EFCaBP), was isolated from the gut cDNA library of amphioxus Branchiostoma belcheri. It consists of 1321 bp with a 636 bp open reading frame encoding a protein of 211 amino acids with a molecular mass of approximately 24.5 kDa. The phylogenetic analysis offers two interesting inferences. First, AmphiCalbin clusters with a group of unnamed EFCaBPs that are differentiated from other identified EFCaBPs. Second, AmphiCalbin falls at the base of the vertebrate unnamed EFCaBPs clade, probably representing their prototype. This is also corroborated by the fact that AmphiCalbin has an exon-intron organization identical to that of vertebrate unnamed EFCaBP genes. Both tissue-section in situ hybridization and whole-mount in situ hybridization prove a tissue-specific expression pattern of AmphiCalbin, with high levels of expression in the digestive system and gonads. It is proposed that AmphiCalbin might play a role in the digestive system and gonads. These observations lay the foundation for further understanding of the function of the unnamed EFCaBPs.  相似文献   

7.
A strange Papilio female specimen with a prominent yellow wing band type very much like P. brevicauda (and also seen in P. machaon, and P. zelicaon) was captured in the forested mountains of southwest Vermont, USA. Despite its brevicauda-like appearance, it had mt-DNA of P. polyxenes. In eastern North America the P. brevicauda (Maritime Provinces of Canada) is currently believed to reflect previous (ancient) hybridization between ancestral P. machaon and P. polyxenes. It is uncertain whether the brevicauda-like wing trait features in the odd Vermont female may be a result of some introgression of P. machaon or P. brevicauda with P. polyxenes in eastern North America as seen also in the Ozark Mountains with P. joanae. Nonetheless, the significance of wing trait analyses in relation to hybrid zones with P. polyxenes remains relevant. The segregation of wing color patterns and hostplant use abilities (efficiencies and growth rates) were examined for laboratory hand-paired F-2 hybrids of P. zelicaon ~ Papilio polyxenes relative to the parental species and primary hybrids. The black adult color pattern characterizing P. polyxenes is presumed to be inherited as a simple autosomal dominant. These hybrids were examined to determine: (i) how F-1 primary hybrid offspring perform relative to the parental types in survival, growth rates, and growth efficiencies; and (ii) whether these larval traits and the adult color patterns might be linked with wing morphology in the F-2 hybrids. While the F-1 hybrids grew as well as the P. polyxenes parent (P. zelicaon was significantly less efficient and slower in growth than either of these), we could not convincingly determine whether the growth performances of the F-2 segregants were linked with the parental wing patterns.  相似文献   

8.
Phaeocystis globosa Scherffel, an organism that causes harmful algal blooms, is a genus of the family Prymnesiophyta (or Haptophyta) with eurythermal and euryhaline characteristics. P. globosa has been confirmed to produce hemolytic substances, which are a mixture of liposaccharides. In the present study, the hemolytic properties of extract of P. globosa are analyzed further. The effects of temperature, pH,different divalent cations, and membrane lipids on extract-induced hemolysis are discussed, as is the possible hemolytic mechanism. The results of the present study showed that the hemolytic activity of the extract was approximately 127.1 hemolytic units (HU)/L. The hemolytic reaction became fastest and a 50% decrease in absorbance was induced at 30 min at 37℃, and at pH 7.0; Hg^2 was the strongest inhibitor of the hemolysis compared with the other divalent cations and many membrane lipids, except for phosphatidic acid, inhibited the hemolytic activity to different degrees. These results suggest that the toxin may make pores in the surface of red blood cells and that Hg^2 either combines with the hemolysin or closes the pores,hence inhibiting its further hemolytic reaction. The toxin probably has no specific membrane receptor in the red blood cell membrane.  相似文献   

9.
Pheidole oxyops builds subterranean nests, with an external architecture that is distinctive and easily recognizable by its wide and specific entrance hole, measuring up to 12.2 cm in diameter, denoting a pitfall-trap. In order to study the nests' internal architecture, seven nests were excavated; four were identified with neutral talc, while the others were cast in cement and then excavated. Measurements were made in order to gain a better understand- ing of their structures, and a photographic documentation was obtained as well. The excavations revealed that the nests are perpendicular relative to the ground, beginning with a cylindrical channel with a mean length of 13.5 cm, containing irregular formations, and whose diameter becomes progressively narrower until the first chamber is formed. As the channel continues, dish-like chambers appear, interconnected by channels that become progressively narrower and longer, while the chambers are arranged at greater distances from each other as nest depth increases. Both channels and chambers are located on the vertical projection of the entrance hole. Nests may reach a depth of up to 5.09 m, with a number of chambers ranging between 4 and 14.  相似文献   

10.
A lower extremity exoskeleton, SJTU-EX, is proposed, which mainly aims to help soldiers and workers to support a payload in motions. To solve the issues of the exoskeleton-environment and exoskeleton-human interactions, four types of foot contact are proposed based on their different kinematic characteristics. By the combination of single leg states, sixteen exo- skeleton states are presented using a series of meaningful notations from the topological point of view. The generalized function set (GF set) theory is employed to achieve the kinematic characteristics of the end effectors in different states. Moreover six mathematical formulations of the dynamics of the exoskeleton and its interactions with the human wearer are developed for different exoskeleton states. The applicability and potential of the proposed classification method are demonstrated by analyzing common lower limb motions, which are described concisely by a sequence of notations. Finally, a new concept of characteristic state is put forward to uniquely indicate the type of motion.  相似文献   

11.
NTRODUCTIONRheumatoid arthritis (RA) is a common disease characterized by the chroniclesion of polyarthritis. The etiology and pathogenesis of RA remain unknown. Autoimmunity to cartilage alltigens may play a significant role in the pathogenesis ofchronic inflammatory polyarthritis. It is commonly accepted that cell mediated immune responses are involved in chronic inflammation since T and B lymphocytes andatigen presenting cells were observed to be enriched in the synovium fluid of RA…  相似文献   

12.
Gamma glutamyl transferases (GGT) are highly conserved enzymes that occur from bacteria to humans. They remove terminal y-glutamyl residue from peptides and amides. GGTs play an important role in the homeostasis of glutathione (a major cellular antioxidant) and in the detoxification of xenobiotics in mammals. They are implicated in diseases like diabetes, inflammation, neurodegenerative diseases and cardiovascular diseases. The physiological role of GGTs in bacteria is still unclear. Nothing is known about the basis for the strong conservation of the enzyme across the living system. The review focuses on the enzyme's physiology, chemistry and structural properties of the enzyme with emphasis on the evolutionary relationships. The available data indicate that the members of the GGT family share common structural features but are functionally heterogenous.  相似文献   

13.
Using electron spin resonance (ESR) spin labeling technique,we have studied the conformation of sulfhydryl groups(-SH) binding sites in membrane proteins and mem brane fluidity of red blood cells(RBCs) from two groups of patients with anemia of chronic renal failure(ACRF).One of the groups is composed of patients who were untreated with recombinant human erythropoietin(r-HuEPO),and the other is composed of patients who were treated with r-HuEPO.The results indicated:1)the conformation of SH group binding site in RBC membrane proteins from former group was different from those of healty people.2)the fluidity in the region near the surface of RBC membrane from former group was lower than those of healthy people.3)However,the above biophysical properties of RBC membrane from later group were normal.We concluded that RBC membrane in patients with ACRF was abnormal,and the treatment of r-HuEPO may promote the production of normal RBCs,thus ameliorate the biophysical properties of RBCs from the patients with ACRF.  相似文献   

14.
Control of a Quadruped Robot with Bionic Springy Legs in Trotting Gait   总被引:1,自引:0,他引:1  
Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the robot has multi-joint legs. This paper presents a three-dimensional model of a quadruped robot which has 6 Degrees of Freedom (DOF) on torso and 5 DOF on each leg. On the basis of the Spring-Loaded Inverted Pendulum (SLIP) model, body control algorithm is discussed in the first place to figure out how legs work in 3D trotting. Then, motivated by the principle of joint function separation and introducing certain biological characteristics, two joint coordination approaches are developed to produce the trot and provide balance. The robot reaches the highest speed of 2.0 m.s-1, and keeps balance under 250 Kg.m.s-1 lateral disturbance in the simulations. The effectiveness of these approaches is also verified on a prototype robot which runs to 0.83 m.s-1 on the treadmill, The simulations and experiments show that legged robots have good biological properties, such as the ground reaction force, and spring-like leg behavior.  相似文献   

15.
16.
Magnetic force transmission of a reciprocating motion is studied by theoretical analysis and experiment. A mathematical model for calculating the magnetic force is derived using the theory of equivalent magnetic charges. An experimental rig is constructed to test the transmission and the model is verified by experiment. Effect of the transmission parameters on the magnetic force is analyzed theoretically from the model, and characteristic of the transmission is studied experimentally. Since the transmission is without direct contact between two elements, it is suitable for application in an organism.  相似文献   

17.
Materials with appropriate adhesive properties are suitable for the fabrication of bionic adhesive pads. In this study, a novel polydimethylsiloxane (PDMS) material enhanced with two types of crosslinkers, carbon nanotubes and graphene sheets, was fabricated. The Contact Angle (CA) and cross-sectional morphology of the new material were investigated and observed using a CA meter and Scanning Electron Microscopy (SEM), respectively. CA measurements indicate that the surface energy of the novel material is twice that of the common PDMS material. SEM observations show that carbon nanotubes and graphene sheets are well dispersed in the polymer, a feature that improves the mechanical properties of the new material. The adhesive performance of this novel composite was tested on an in-house fabricated friction machine. Results show that at a preload of only 50 mN, the adhesion of the novel PDMS material is up to -3.7 times that of common PDMS. The maximum macroscale shear strength and normal adhesion reach 4 N·cm^-2 and 1 N·cm^-2, respectively. The adhesive capability of the material is maintained even after hundreds of times of repeated use. This novel material exhibits excellent adhesion, sufficiently high elastic modulus and high repeatability at low preloads.  相似文献   

18.
Viral nonstructural proteins in both enveloped and non-enveloped viruses play important roles in viral replication. Protein NS38 of Grass carp reovirus (GCRV), has been deduced to be a non-structural protein, and, consistent with other reoviruses, is considered to cooperate with the NS80 protein in viral particle assembly. To investigate the molecular basis of the role of NS38, a complete protein was expressed in E.coli for the first time. It was found that there is a better expression of NS38 induced with IPTG at 28 ℃ rather than 37 ℃. In addition, the antiserum of NS38 prepared with purified fusion protein and injected into rabbit could be used for detecting NS38 protein expression in GCRV infected cell lysate, while there is not any reaction crossed with purified virus particle, confirming NS38 is not a component of the viral structural protein. The result reported in this study will provide evidence for further viral protein-protein and protein-RNA interaction in dsRNA viruses replication.  相似文献   

19.
20.
NIZUMEI  NINGYI 《Cell research》1993,3(2):165-171
The characteristics of the particulate mouse centromere enriched fraction from isolated nuclei obtained in our laboratory were investigated by indirect immunofluorescence,test of the activity of microtubule organizing center(MTOC),SDS-PAGE,and fluorescence in situ hybridization.Most of the particles of the fraction are complexes of DNA and kinetochore proteins and show MTOC activity.The DNA isolated from the fraction can hybridize with DNA in the regions of the primary constrictions of all chromosomes of ascions of the primary constrictions of all chromosomes of ascites cells.The kinetochore proteins isolated from the fraction are mainly those with molecular weight of 55 KD and 59 KD.Results suggested that the fraction obtained is a centromere enriched nuclear fraction as indicated in our previous report.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号