ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Language
  • 1
    Keywords: Earth sciences. ; Evolution (Biology). ; Earth Sciences. ; Evolutionary Biology.
    Description / Table of Contents: 1 Introduction -- 2 Palaeogeographical settings of South China in the Changhsingian to Induan and palaeogeographic distribution of the studied Permian Triassic Boundary sections -- 3 Description of the studied Permian Triassic Boundary sections of South China -- 4 Age analysis and correlation -- 5 Temporal and spatial processes and dynamics of the Permian Triassic Boundary mass extinction (PTBME) in South China.
    Abstract: This book timely provides high-quality records of 32 PTB sections across different depositional settings from terrestrial to marine facies in South China, including descriptions of lithologies, high-resolution correlation of key boundaries and fossil occurrences at each section. This book also analyzes the patterns and processes of the community and ecosystem evolution over space and through time in the lead to the end-Permian mass extinction, and critically analyzes the mostly debated hypothesis, anoxia and volcanism, which were considered as the causes of mass extinction, based on the data from the studied sections of South China, together with materials from other regions of the world.
    Type of Medium: Online Resource
    Pages: XII, 287 p. 98 illus., 66 illus. in color. , online resource.
    Edition: 1st ed. 2023.
    ISBN: 9789819993505
    Series Statement: New Records of the Great Dying in South China,
    DDC: 550
    Language: English
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 72 (1990), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Cholera toxin (CT) stimulated phospholipase activity and caused [3H]arachidonic acid (3H-AA) release in a murine macrophage/monocyte cell line. Pretreatment of cells with dexamethasone, a phospholipase A2 (PLA2) inhibitor, did not affect CT-induced 3H-AA release. In contrast, aspirin, which is an inhibitor of phospholipase C (PLC), blocked CT-induced 3H-AA release and subsequent prostaglandin (PC) synthesis. The inhibitory effect of aspirin was dose dependent, with 4 mM reducing the CT response by approximately 50%. Similarly, inhibition was time dependent, occurring when the drug was added to the culture medium as late as 30 min after CT. Brief exposure (30 min) of the cells to aspirin did not alter their subsequent response to CT, but 3H-AA release from cells exposed to aspirin for 2.5 h was irreversibly inhibited. The data suggested that CT stimulation of AA metabolism may involved increased PLC activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 280-283 (Feb. 2007), p. 1353-1356 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The friction behavior of Ti3SiC2 sliding against low carbon steel was studied. Tests were carried out on a block-on-disk type friction tester, with the normal pressures from 0.2 MPa to 0.8 MPa and the sliding speed of 20 m/s. The results showed that, irrespective of the normal pressure, the friction coefficient exhibits a transition period in the initial stage of a sliding friction process, in which the friction coefficient increases from an initial value and tends to a saturation value, and then entersinto a relatively steady stage. The results also showed that, the friction coefficient of the steady stage decreases gradually from 0.35 to 0.26 with increase in normal pressure from 0.2 MPa to 0.8 MPa. The friction surfaces were observed by using SEM. It was found that all the surfaces were covered by a layer consisting of the frictional products with antifriction effect, and that the denseness and thethickness of the layer were increased with increase in normal pressure applied
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 353-358 (Sept. 2007), p. 1556-1559 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The purpose of this study is to determine the bi-axial flexural strength, weibull modulusand fracture mode of bilayered alumina glass-infiltrated core and the veneering porcelain. Fortydisk specimens were fabricated from alumina glass-infiltrated core (HSDC-A) and veneerporcelain (Vintage AL). The specimens were equally divided into four groups as: MV, monolithicspecimens of veneer material; MC, monolithic specimens of core material; BV, bilayeredspecimens with the veneer in tension; BC, bilayered specimens with core material in tension.Mean flexure strength, standard deviation and associated Weibull modulus were determined usingbi-axial flexure (ball-on-ring) for each group. Both optical and scanning electron microscopy wereemployed for identification of the fracture mode and origin. The surface loaded in tensioninfluenced the bi-axial flexural strength and reliability of the composites. The frequency ofspecimen delamination, Hertzian cone formation and sub-critical radial cracking in the bilayereddiscs are also dependent on the surface loaded in tension
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 364-366 (Dec. 2007), p. 117-122 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A novel algorithm and experiment using phase retrieval to test aspheric mirror withoutauxiliary optical elements has been developed. To test aspheric mirror without auxiliary opticalelements, a new algorithm has been invented to overcome the calculation difficulty due to thesignificant departure of aspheric surface from a sphere. In this algorithm, the aspheric surface isfitted into several annular ellipse sub-apertures, and each sub-aperture aberration can be retrievedthe same as ball mirror testing. The whole aspheric surface can be retrieved by stitching all the subaperturestogether. An experiment has been carried out to test the validity of this algorithm
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 364-366 (Dec. 2007), p. 584-589 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In order to keep the stability of tool’s removal function, it is required that the anastomosisbe tight between the tool and workpiece surface in Computer-controlled Optical Surfacing (CCOS).In this paper, the influence of tool’s character on anastomosis status is firstly studied. The relationmodel on the ratio of radius to thickness, Young's modulus of the tool, normal asphericity andnormal arc height of workpiece surface is established, and the macroscopical condition of tightanastomosis is derived in aspheric optics machining. According to the microcosmic distribution ofsurface error, the mathematical relation between anastomosis error and removal rate is researched.In the end, the influence rule of anastomosis status on the convergence ratio of residual error isanalyzed in machining zone. Based on the conclusion of machining instance, it is found thatworkpiece material would be fast removed in middle contact zone when the peak value of tool’sremoval function locates in its center position
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 364-366 (Dec. 2007), p. 745-749 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A new special-purpose optical coordinate measurement machine has been developed withthe cylinder coordinates to solve the problem of testing aspherics with full aperture in the stage ofgrinding and pre-polishing .A full aperture measurement was made by testing several meridians inthe point by point manner. In the aspect of hardware, the system is composed mainly by an ultrapreciseair guide-way, realizing the linear motion, and a graduator, realizing the rotary motion. Inthe aspect of software, the mathematical model of the system was analyzed and a new algorithm forthe full-aperture testing of rotationally symmetric aspherics was built. The testing software anddata-processing software are written on the VC++6.0 and Matlab6.5 platform respectively. Themaximum measurement range of the system is 600mm, the maximum sag: 25mm, the minimumsampling step, 1 mm and the accuracy is better than 1um in full scale, after the compensation of thesystematic errors. The requirement in the grinding and pre-polishing process for the test of asphereshas been satisfied. The real experiments indicate: the system runs well and has a good repeatabilityand accuracy
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 364-366 (Dec. 2007), p. 756-761 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Ion beam Figuring (IBF) of optical mirror is a polishing process based on CCOS with theapplication of ion sputtering effects. The material removal mechanism is in the atom scale, whichcan enhance the precision of the target surface to tens of nanometers. Without contact, this processcan also promote the subsurface quality. In this paper, the Ion Beam Figuring Machine (IBFM) isintroduced,which realizes the relative motion between the target surface and the ion source.Firstly, we describe the design method, the machine configuration and principal technicalparameters. With the configuration and motion ability described, we introduce different scanningmodes for surfaces of different scales respectively. Secondly presented is the precision analysismethod for IBFM. Based on the CCOS principle, the relation between the convergence rate andpositioning errors are deduced. This relation describes the precision requirement of machiningprocess. Finally, the postposition algorithm of IBFM is analyzed. According to coordinate transitionand rotation, the general transfer model for different scanning modes is given
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 22-24 (Jan. 1987), p. 409-422 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 280-283 (Feb. 2007), p. 1357-1360 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The Ti3SiC2 samples with a second phase TiC, prepared by hot-pressing progress route, were rubbed against low carbon steel disk with a sliding speed of 20 m/s under normal pressure 0.8 Mpa in atmosphere on a block-on-disk type friction tester. The morphology was observed by scanning electron microscope (SEM) and meanwhile the composition was checked by energy dispersion spectroscopy (EDS). X-ray diffraction (XRD) patterns show some impurity phases containing Ti, Si and Fe oxides in the samples. The possible tribo-chemical reaction mechanism on surface layer of Ti3SiC2 was suggested
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...