نتایج جستجو برای: almost a century and a half ago
تعداد نتایج: 20372301 فیلتر نتایج به سال:
any change in the refractive index of a laser active medium can lead to serious degradation of beam quality, laser beam modes, laser performance and variation in the intensity distribution. alteration in the refractive index of laser active medium is especially notable in high power lasers. it is clear that in the laser beam production, the pumping agent induces a great amount of heat which...
This article summarizes the life and work of James Barrett Brown, MD (1899-1971), a plastic surgeon from St Louis, Mo, whose many contributions to the knowledge of surgery include his pioneering use of large split-thickness skin grafts to resurface defects. Along with a coauthor, he published an excellent book on radical neck dissection in 1954 (Neck Dissections, published by Charles C. Thomas,...
DNA barcoding is a new term introduced in to scientific literatures by Hebert and coworkers almost a decade ago. The concept of barcoding alone is well-known to the public: a series of black bars printed on many commercial products (Universal Product Code), which are used to distinguish different products. Advances made in molecular biology and molecular techniques late 20th century e.g. sequen...
For a long time, scientists have tried to describe disorders just by genetic or environmental factors. However, the role of epigenetics in human diseases has been considered from a half of century ago. In the last decade, this subject has attracted many interests, especially in complicated disorders such as behavior plasticity, memory, cancer, autoimmune disease, and addiction as well as neurod...
let h be a separable hilbert space and let b be the set of bessel sequences in h. by using several interesting results in operator theory we study some topological properties of frames and riesz bases by constructing a banach space structure on b. the convergence of a sequence of elements in b is de_ned and we determine whether important properties of the sequence is preserved under the con...
the purpose of this study is to investigate the relationships between teachers’ immediacy behaviors and iranian students’ willingness to talk in english classes. analysis of the results from willingness to talk scale represents a relatively high level of willingness to talk in english classrooms among iranian language learners. the total mean score of students’ willingness to talk was 66.3 ou...
this thesis is going to delineate the concept of the reader as implied in 18th century literary theory; based on the study of the major reader oriented elements of criticism of the age-taste, the sublime, and aesthetic pleasure-its aim is to explain what sott of reader is implied and what kind of response on the part of the reader is proposed in 18th century english literary theory and aestheti...
the ability of composing a coherent and extended piece of writing in second language is considered as a fundamental factor to convey information and ideas of learners through the academic issues. although learners may achieve a perfect academic writing skill through assigning the l2 tasks in content based instruction, but demonstration of their abilities may be related to their ability in l1 es...
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