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1.
The problems facing the mycologist centre on the difficulty of distinguishing between the individual and the population, the degree of host or substratum specialization and the limited range of morphological characters available for use as denning taxa. The use of the categories 'variety' and 'forma specialis' is considered, and examples are given of their application in the cereal rusts and in the genera Phoma and Fusarium. Micro-evolutionary trends in Auricula auricula are also considered and are used to illustrate how amenable fungi are to studies on speciation.  相似文献   

2.
3.
The application of stable isotopes in biomedical research   总被引:1,自引:0,他引:1  
Many of the ways in which isotopes are used in biomedical research are reviewed. The use of stable isotopes in stable isotope dilution assays, for metabolite identification and in pharmacokinetic studies, is discussed and relevant examples are given to illustrate the various points made. Isotope effects and their implications for future drug design are considered. Some of the toxicity problems associated with the use of stable isotopes are also considered. Finally, a brief subjective view of possible future advances is made.  相似文献   

4.
Methods that use immunoaffinity chromatography (IAC) for sample preparation or detection are becoming increasingly popular as tools in the analysis of biological and nonbiological compounds. This paper presents an overview of immunoaffinity chromatography and examines some recent developments of this technique in analytical applications. The emphasis is placed on HPLC-based IAC methods or those that combine IAC with other instrumental techniques; however, novel approaches that employ low-performance IAC columns for chemical quantitation are also considered. Particular applications that are examined include (1) the use of IAC in the direct detection of analytes, (2) the extraction of samples by IAC prior to on- or off-line detection by other methods, (3) the use of IAC in chromatographic-based immunoassays, and (4) the development of postcolumn reactors based on IAC for the detection of analytes as they elute from other types of chromatographic columns. The advantages and limitations for each approach are considered. In addition, a summary is provided of reports in the literature that have used IAC for these various formats.  相似文献   

5.
Forests are a significant pool of terrestrial carbon. A key feature related to forest biomass harvesting and use is the typical time difference between carbon release into and sequestration from the atmosphere. Traditionally, the use of sustainably grown biomass has been considered as carbon neutral in life cycle assessment (LCA) studies. However, various approaches to account for greenhouse gas (GHG) emissions and sinks of forest biomass acquisition and use have also been developed and applied, resulting in different conclusions on climate impacts of forest products. The aim of this study is to summarize, clarify, and assess the suitability of these approaches for LCA. A literature review is carried out, and the results are analyzed through an assessment framework. The different approaches are reviewed through their approach to the definition of reference land‐use situation, consideration of time frame and timing of carbon emissions and sequestration, substitution credits, and indicators applied to measure climate impacts. On the basis of the review, it is concluded that, to account for GHG emissions and the related climate impacts objectively, biomass carbon stored in the products and the timing of sinks and emissions should be taken into account in LCA. The reference situation for forest land use has to be defined appropriately, describing the development in the absence of the studied system. We suggest the use of some climate impact indicator that takes the timing of the emissions and sinks into consideration and enables the use of different time frames. If substitution credits are considered, they need to be transparently presented in the results. Instead of carbon stock values taken from the literature, the use of dynamic forest models is recommended.  相似文献   

6.
Stimulation of bioprocesses by ultrasound   总被引:3,自引:0,他引:3  
Ultrasound (US) has become a ubiquitous technological process in a large variety of scientific disciplines. However, little information exists on the use of ultrasound to enhance biological processes and/or processing and consequently this paper provides an overview of work reported to date on this topic. This review provides a brief introduction to ultrasound and the history of ultrasound as applied to bioprocesses. This is followed by a discussion of the influence of US on discrete enzyme systems, enzymes used in bioremediation, microbial fermentations and enzymatic hydrolysis of biopolymers. Augmentation of anaerobic digestion by US is then considered along with enhancement of enzymes in food science and technology. The use of ultrasonically stimulated enzymes in synthesis is then considered and other relevant miscellaneous topics are described. It is concluded that the precise mechanism of action of US in bio-processing remains to be elucidated though a variety of plausible suggestions are made.  相似文献   

7.
Abstract

The application of liposomes as carriers for imaging agents is considered. Liposomes loaded with the appropriate contrast agents have been shown to be suitable for gamma-, magnetic resonance (MR), computed tomography (CT) and ultrasound imaging. The methods are briefly described to prepare liposomes loaded with different contrast agents, as well as some data on their biodistribution. The application of contrast-loaded liposomes for liver/spleen, tumor, lymph nodes, infection and inflammation sites, myocardial infarction, and blood pool imaging is briefly reviewed together with some data available on the use of liposome for the ophtalmological imaging. New trends in the use of contrast-loaded liposomes are also considered, such as the application of long-circulating polymer-modified liposomes for imaging purposes and development of new lipid-coated liposome-like contrast agents.  相似文献   

8.
The data on the morphogenesis, biology and genetics of human immunodeficiency virus, as well as on the epidemiology of AIDS, are presented. Different assay systems developed in the USSR for the diagnosis of AIDS are described. The prospects for improving diagnostic techniques with the use of gene engineering are considered.  相似文献   

9.
Nirupama Mallick 《Biometals》2002,15(4):377-390
This presentation comprises a review on the use of immobilized algae for wastewater nitrogen, phosphorus and metal removal purposes. Details of the use of immobilized algae, the techniques of immobilization and the effects of immobilization on cell function are included. Particularly relevant in their use for heavy metal removal from wastewaters; upon enriching the biomass in metal, can be recoverd, thereby providing economic advantages. The use of immobilized microalgae in these processes is very adequate and offers significant advantages in bioreactors. The future of this area of algal cell biotechnology is considered.  相似文献   

10.
With changes in the age structure and oral health in the population, changes in the pulpo-dentinal complex are becoming more relevant clinically. Age-related changes in the structure of dentine and pulp are reviewed. The influence of these changes on restorative dentistry are considered with particular emphasis on endodontics and the use of adhesive restorative materials.  相似文献   

11.
The 2004 Statistics of Scientific Procedures on Living Animals were released by the Home Office in December 2005. They indicate that, for the third year running, there has been a significant increase in the number of laboratory animal procedures undertaken in Great Britain, and that increasing numbers of animals are involved. The overall trends in the use of toxicological and non-toxicological procedures involving animals are described. Particular emphasis is placed on the production and use of genetically modified animals, the production of biological materials, and acute toxicity testing. The use of non-human primates and dogs is also discussed. The implications of these latest statistics are considered with reference to the implementation of the Three Rs and their consequences for animal welfare.  相似文献   

12.
Kuhlmann I 《Cytotechnology》1995,19(2):95-105
This article describes the historical development of the prophylactic use of antibiotics in cell culture as well as their effects on cells. The influence of antibiotics on cell morphology, cellular degeneration and cell death and cellular function is summarized. Cellular DNA as well as protein synthesis are affected which can lead to interference with, or even changes in, metabolic processes. Such effects must be considered in cell culture research. As antibiotics are used in multifold ways, the otherwise standardized conditions in cell culture are no longer comparable. The prophylactic use of antibiotics is rejected for scientific reasons.  相似文献   

13.
The possibility was considered to use the transverse thermophoresis of analytes in the capillary for capillary electrophoresis (CE) to control the separation process, decrease the peak width due to thermal effects and provide new separation parameters in CE. As the examination has shown, in non-aqueous buffers the Joule heating in the capillary for CE can provide transverse temperature gradients comparable with the temperature gradients in conventional devices for thermal field flow Fractionation (ThFFF). It was proposed to use the non-uniform velocity profile of analytes caused by the transverse temperature gradient and the temperature dependence of the buffer viscosity for the FFF-like separation of analytes besides CE separation. The expressions for the peak parameters have been derived, where the non-uniform transverse analyte concentration distribution due to the thermophoresis is taken into account, and the possibilities based on FFF-CE principles are discussed. As possible objects of this hyphenated technique, macromolecules and particles are considered.  相似文献   

14.
Metaphor influences the construction of biological models and theories and the analysis of its use can reveal important tools of thought. Some aspects of biological organisation are investigated through the analysis of metaphors associated with treating biosystems as a kind of text. In particular, the use of glue and verbs is considered. Some of the reasons why glue is important in the construction of hierarchies are pursued in the light of specific examples, and some of the conceptual links between glue in biology and other domains is discussed. Verbs are shown to be important in the construction of networks. Some of the relations between glue, verb and text are considered and the text metaphor is placed within a much broader context of ideas associated with form, relation and system. The paper concludes with comments on the nature of biological information and the need for extending or better understanding the verbal vocabulary.  相似文献   

15.
The haematological assessment of the health of freshwater fish   总被引:5,自引:0,他引:5  
A review is made of some selected literature regarding the use of haematological techniques in freshwater fish pathology. Comparisons are drawn with the techniques already widely used in human pathology for the assessment of health and for aid in diagnosis of various diseases and conditions. The need for information on normal values, and on the conditions under which these were formulated, and the factors affecting them is stressed. The use of haematological values in assessing sublethal concentrations of environmental pollutants and the possibility of chromosomal changes are considered.  相似文献   

16.
1. A review of the effects of long-term administration of antidepressants and neuroleptics on receptors in the central nervous system is presented. 2. The effects of antidepressants on adenylate cyclase activity and on receptor binding in brain tissue are discussed. Effects on a variety of receptor types are considered. 3. The utilization of electrophysiological, behavioral, and neurochemical studies to assess receptor function after chronic antidepressant administration is discussed, as is the use of peripheral receptor estimations in clinical studies. 4. Animal studies on the actions of chronic administration of neuroleptics on pre- and postsynaptic dopamine receptors are reviewed. Effects of these drugs on dopamine receptors in humans are considered from the following perspectives: postmortem and in vivo binding studies in schizophrenia, tardive dyskinesia, and central versus peripheral receptor estimation.  相似文献   

17.
The advances of the method of atomic force microscopy for investigating the animal cells and an analysis of its development have been reviewed, with much attention being given to studies of living cells. The features and problems of the method have been considered, and a number of special methods based on the use of atomic force microscopy have been analyzed. The problems of choosing the geometry of probes for studies of animal cells, determination of cell adhesion on substrate, mapping of the cell surface using chemically modified cantilevers, and the distribution of molecular components inside the cell with the use of micro- and nanosurgical approaches have been discussed. The problems of combining the atomic force microscopy with optical and laser scanning confocal microscopy have been considered. Possible applications of the method in biotechnology and medicine are discussed.  相似文献   

18.
On a six-dimensional representation of RNA secondary structures   总被引:2,自引:0,他引:2  
In this paper, we proposed a 6-D representation of RNA secondary structures. The use of the 6-D representation is illustrated by constructing structure invariants. Comparisons with the similarity/dissimilarity results based on 6-D representation for a set of RNA secondary structures, are considered to illustrate the use of our structure invariants based on the entries in derived sequence matrices restricted to a selected width of a band along the main diagonal.  相似文献   

19.
This study adopts an integrated life-cycle approach to assess overall carbon saving related with the utilization of wood pellets manufactured using pulpwood and logging residues for electricity generation. Carbon sequestered in wood products and wood present in landfills and avoided carbon emissions due to substitution of grid electricity with the electricity generated using wood pellets are considered part of overall carbon savings. Estimated value of overall carbon saving is compared with the overall carbon saving related to the current use of pulpwood and logging residues. The unit of analysis is a hectare of slash pine (Pinus elliottii) plantation in southern USA. All carbon flows are considered starting from forest management to the decay of wood products in landfills. Exponential decay function is used to ascertain carbon sequestered in wood products and wood present in landfills. Non-biogenic carbon emissions due to burning of wood waste at manufacturing facilities, wood pellets at a power plant, and logging residues on forestlands are also considered. Impacts of harvest age and forest management intensity on overall carbon saving are analyzed as well. The use of pulpwood for bioenergy development reduces carbon sequestered in wood products and wood present in landfills (up to 1.6 metric tons/ha) relative to a baseline when pulpwood is used for paper making and logging residues are used for manufacturing wood pellets. Avoided carbon emissions because of displacement of grid electricity from the electricity generated using wood pellets derived from pulpwood fully compensate the loss of carbon sequestered in wood products and wood present in landfills. The use of both pulpwood and logging residues for bioenergy development is beneficial from carbon perspective. Harvest age is more important in determining overall carbon saving than forest management intensity.  相似文献   

20.
This review deals with the problem of enzyme stabilization without the use of carriers. The following main types of stabilization are considered: addition of low-molecular weight compounds; addition of organic solvents; chemical modification of key functional groups on enzymes; intramolecular crosslinking with bifunctional reagents. The mechanisms of the procedures are discussed, and further methods for stabilizing enzymes without the use of carriers are suggested.  相似文献   

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