1. a process in which a neutron colliding with an atomic nucleus causes fission and the ejection of one or more other neutrons, which induce other nuclei to split 2. a chemical reaction in which the product of one step is a reactant in the following step Collins Discovery Encyclopedia,...
critical. The word is unfortunate but understandable when it is recalled that the term ‘critical’ dates back to 12 December 1942. On that day Enrico Fermi and his colleagues first achieved a self-sustained chain reaction, an achievement which had aspects of uncertainty and peril for the ...
For the individual steps of the growth reaction one needs only a relatively small activation energy and therefore through a single activation step ( the actual initiation reaction) a large number of olefin molecules are converted, as is implied by the term "chain reaction". 对于生长反应的每个步骤...
Two methods are used to obtain metaphases: the short-term or semi-direct culture (STC) and long term culture (LTC). The main advantage of STC is that there is no risk of maternal contamination, and of LTC that no false-negative findings are described in the literat...
However, prolonged implantation of PE and PMMA and other such polymers will result in some chain scission due to cellular action in which radical species are formed. Step-growth polymerizations are characterized by the stepwise reaction of the functional groups of the reactants. These reactions ...
Define chain stitch. chain stitch synonyms, chain stitch pronunciation, chain stitch translation, English dictionary definition of chain stitch. n. 1. A decorative sewing stitch in which loops are connected like the links of a chain. 2. A basic crochet s
While COVID-19 could prompt investors to become more resilient and increasingly factor in ESG, there is also the possibility of emphasizing short-term gains over longer-term sustainability concerns. Environmental issues may temporarily be deprioritized. Efforts to mitigate the risk of future crises ar...
means of a chain reaction, one monomer molecule after the other is added (2000~20000 monomers per second) until the active state is terminated through a different type of reaction. The polymerization is a chain reaction in two ways: because of the reaction kinetic and because as a reaction ...
Long-term evidence suggests that the semaphorin (Sema) family comprises neuron guidance molecules during embryonic development. These factors provide repulsive or attractive cues for neurocyte migration and growth.84,85To date, Semas have been reported to be involved in several other physiological proce...
); after 600 h of reaction, 46% of initial activity has been lost. In contrast, Pd/CNT + ZnZrOx catalyst shows superior long-term performance; the methanol yield over Pd/CNT + ZnZrOx reaches 13.5% (STYMeOH = 0.90 g g...