共查询到20条相似文献,搜索用时 62 毫秒
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本文通过研究肼感染显影动力学,对肼感染显影的显影速度及其活化能进行测试和计算,籍以讨论有关肼感染显影过程的机理。实验结果表明:肼感染显影的早期是直接显影,活化能低;后期是灰化成核显影,活化能高;而低曝光量潜影核无灰化成核显影,活化能较高。高反差、短趾部的形成原因是由于显影加速和显影抑制的竞争结果。 相似文献
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NataliaP TarasovaD 《化学教育》2002,23(12):15-25,40
Education is a very important factor in human development,Human development does not start with the possession of goods,as this is one measure of development.It begins with people and their education.There are ,of course,other human development resouces that are of importance,However,without education all other resources remain as latent potentials to support human development. 相似文献
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Z P Xie T Wang Y J Zhu 《Science in China. Series B, Chemistry, life sciences & earth sciences》1989,32(2):148-154
Whole-cell clamped myoballs are placed into direct visible contact with the growth cones of isolated neurons in embryonic Xenopus culture to serve as probe of acetylcholine (AcCHo) release in order to determine whether these neurons are cholinergic or not. Using a G omega -seal, whole-cell recording method, the electrophysiological properties of these identified cholinergic neurons are studied. It is found that these embryonic neurons, like adult frog motor neurons, exhibit repetitive firings in a certain embryonic developing stage. A development of repetitive firings is observed simultaneously. Tracing the development of one neuron, we find that the development of repetitive firing is completed at the 48th h after fertilization. Tetrodotoxin (TTX) which blocks Na+ channels can abolish all firings; and tetraethyl ammonium chloride (TEA), the blocker of K+ channels, reverses this development, i.e. it makes the repetitive firings disappear again. These data show that the nature of the development of repetitive firings is the development of K+ channels. 相似文献
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Whole-cell clamped myoballs are placed into direct visible contact with the growth cones of isolated neurons in embryonic Xenopus culture to serve as probe of acetylchollne (AcCHo) release in order to determine whether these neurons are cholinergic or not. Using a GQ-seal, whole-cell recording method, the electrophysiological properties of these identified cholinergic neurons are studied. It is found that these embryonic neurons, like adult frog motor neurons, exhibit repetitive firings in a certain embryonic developing stage. A development of repetitive firings is observed simultaneously. Tracing the development of one neuron, we find that the development of repetitive firing is completed at the 48th h after fertilization. Tetrodotoxin (TTX) which blocks Na~+ channels can abolish all firings; and tetraethyl ammonium chloride (TEA), the blocker of K~+ channels, reverses this development, i. e. it makes the repetitive firings disappear again. These data show that the nature of the development of repetiti 相似文献
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DSC purity analysis is based on thermodynamic phase diagrams for substances (purity ≥98%) which undergo a melting point. Impurities which have eutectic behaviour with the analyte are determined together. DSC purity analysis obtained from a single melting event of a 1–2 mg sample is, therefore, extremely attractive for the global assessment of eutectic impurities. The main advantages in early development lie in the very small amount of material necessary and the very fast analysis time. However, the DSC purity analysis cannot replace chromatographic methods which deliver specific individual levels of impurities. Furthermore, a complete validation of a DSC purity method is difficult and time consuming. Despite these limitations, DSC is the best support for the development of chromatographic methods, for purity profile and stability assessment during pharmaceutical development. Parameters of purity determination and validation aspects are discussed. Examples of use in pharmaceutical development are given. 相似文献
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Design of fluorescent materials for chemical sensing 总被引:1,自引:0,他引:1
There is an enormous demand for chemical sensors for many areas and disciplines. High sensitivity and ease of operation are two main issues for sensor development. Fluorescence techniques can easily fulfill these requirements and therefore fluorescent-based sensors appear as one of the most promising candidates for chemical sensing. However, the development of sensors is not trivial; material science, molecular recognition and device implementation are some of the aspects that play a role in the design of sensors. The development of fluorescent sensing materials is increasingly captivating the attention of the scientists because its implementation as a truly sensory system is straightforward. This critical review shows the use of polymers, sol-gels, mesoporous materials, surfactant aggregates, quantum dots, and glass or gold surfaces, combined with different chemical approaches for the development of fluorescent sensing materials. Representative examples have been selected and they are commented here. 相似文献
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S. Küppers 《Accreditation and quality assurance》1998,3(10):412-415
Two examples of the use of measurement uncertainty in a development environment are presented and compared to the use of validation. It is concluded that measurement uncertainty is a good alternative to validation for chemical processes in the development stage. Some advantages of measurement uncertainty are described. The major advantages are that the estimations of measurement uncertainty are very efficient, and can be performed before analysis of the samples. The results of measurement uncertainty influence the type of analysis employed in the development process, and the measurement design can be adjusted to the need of the process. 相似文献
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Ion trap mass spectrometry: a personal perspective 总被引:7,自引:0,他引:7
Stafford G 《Journal of the American Society for Mass Spectrometry》2002,13(6):589-596
This paper is a personal perspective of the commercial development of the three-dimensional quadrupole ion trap mass spectrometer. Early ion trap invention and development which dates back to 1953, is described. The development of the ion trap is traced through three ages with the last age being where commercial development takes place. Key technical breakthroughs in ion trap technology and commercialization are presented and described up to the present time. 相似文献
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Theoretical equations are given to relate resolution with development distance. Comparative experiments undertaken with quaternary ammonium compounds as test substances and using a selection of basic drugs are presented. As expected, resolution decreases with shorter development distance. However, this effect is less pronounced for compounds with small Rf values and when the spot size at the starting point is kept small. It was also shown that, for correctly assessing resolution in relation to development distance, the amounts of material spotted have to be decreased for shorter development distances. 相似文献
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Software and computer systems are tested during all development phases. The user requirements and functional specifications
documents are reviewed by programmers and typical anticipated users. The design specifications are reviewed by peers in one
to two day sessions and the source code is inspected by peers, if necessary. Finally, the function and performance of the
system is tested by typical anticipated users outside the development department in a real laboratory environment. All development
phases including test activities and the final release follow a well-documented procedure.
Received: 17 May 1997 · Accepted: 30 June 1997 相似文献
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Rodriguez-Mozaz S Lopez de Alda MJ Barceló D 《Analytical and bioanalytical chemistry》2006,386(4):1025-1041
Recent advances in the development and application of biosensors for environmental analysis and monitoring are reviewed in
this article. Several examples of biosensors developed for relevant environmental pollutants and parameters are briefly overviewed.
Special attention is paid to the application of biosensors to real environmental samples, taking into consideration aspects
such as sample pretreatment, matrix effects and validation of biosensor measurements. Current trends in biosensor development
are also considered and commented on in this work. In this context, nanotechnology, miniaturisation, multi-sensor array development
and, especially, biotechnology arise as fast-growing areas that will have a marked influence on the development of new biosensing
strategies in the near future. 相似文献
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The analytical characterization required in the development and in the quality control of new ceramics is discussed. For the basic substances, the problems encountered in the development of routine techniques for a direct and reliable analysis of Al2O3, AlN, Si3N4, SiC, and ZrO2 powders are reported. Among the atomic spectrometric methods, especially slurry atomization ICP-spectrometry is described. Also the problems encountered in the development of combined procedures as required for the characterization of reference samples are presented. Methods for the direct bulk analysis of ceramics and microdistributional analysis, as they are now under development with laser-based techniques and various probe techniques, are described as well. 相似文献
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R.G. Graham M.A. Bergougnou R.P. Overend 《Journal of Analytical and Applied Pyrolysis》1984,6(2):95-135
The development of viable fast pyrolysis processes for biomass and other carbonaceous feedstocks will offer significant advantages over conventional pyrolysis, flash pyrolysis and gasification processes with respect to product yield quality and flexibility. Fast pyrolysis is defined and related to other biomass thermochemical conversion processes in some detail. Brief references are made to corresponding coal, hydrocarbon and oil conversion research and development. Proposed mechanisms and chemical pathways are reviewed, potential products. product upgrading and product applications are identified. Fast pyrolysis research is reviewed on both the fundamental bench-scale level and the applied process development level. 相似文献
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Upton RT 《Journal of AOAC International》2010,93(5):1349-1354
TLC characterizations are among the key identity tests in most pharmacopoeial monographs. Pharmacopoeial standards are typically used by industry as a basis for meeting QC requirements and current good manufacturing practices (cGMPs). TLC is a relatively low-cost, highly versatile tool for developing specifications for raw materials, as well as for the various preparations for which pharmacopoeial standards are created. In addition to its use in the development of identity tests, TLC is a valuable tool for screening plant samples that pharmacopoeias must review in the development of monographs and botanical reference materials (BRMs). Specifically, HPTLC is the ideal TLC technique for these purposes because of its increased accuracy, reproducibility, and ability to document the results, compared with standard TLC. Because of this, HPTLC technologies are also the most appropriate TLC technique for conformity with GMPs. This article highlights the manner in which HPTLC is used by the American Herbal Pharmacopoeia (AHP) in the development of AHP monograph identity standards, the identification of adulterating species, and the development of AHP-verified BRMs. 相似文献
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The origins and development of the application of the ICP as an atmospheric pressure ion source for mass spectrometry are described and an outline of the technique as it is currently used for multi-element ultratrace analysis of solutions is given. Present achievements and limitations are discussed and the areas of likely development in the near future are outlined. 相似文献
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What conductors are to their orchestras, biomarkers are to their associated technologies. Building fundamental science, supporting
early diagnosis of diseases and following their progression, improving efficacy and safety of treatments, optimizing patient
selection and adapting dosing of drugs, helping decide which therapy is most appropriate; these are examples of a few contexts
in which biomarkers are key players. Technology development can definitely not escape being associated with these steps. In
other words, today’s biomarkers are the thermometers of tomorrow’s therapies. This review provides an overview of recently
established platforms as well as new and upcoming technologies for biomarker development in the context of drug development.
The roles as well as the pros and cons of different disciplines such as genetics, genomics, proteomics, metabonomics, and
assay development will be discussed. 相似文献