首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Raphael Meldola (1849–1915), English industrial and academic chemist, spectroscopist, naturalist, educator and lobbyist for science, is today almost a forgotten scientist whose life is celebrated only with a medal awarded by the Royal Society of Chemistry that honors achievement by younger chemists. In the 1870–80s, however, he invented a number of important synthetic dyestuffs including the cotton dyes isamine blue and Meldola's blue, and also naphthol green B, all of which have had application in biology and medicine. I describe here the early emergence of the synthetic dye industry, the first science-based industry, Meldola's role in its development, and his own inventions. Meldola's wide ranging achievements in science led to appointments as president of important professional scientific and manufacturers' societies. He was a fervent disciple of natural selection, a correspondent of Charles Darwin, and a prominent 19th-century neo-Darwinian. In 1886, drawing on analogies with evolutionary theory, he warned the British that neglect of science, particularly chemistry, would lead to industrial decline and even extinction, though his message generally was ignored, at least until 1914.  相似文献   

2.
Raphael Meldola (1849-1915), English industrial and academic chemist, spectroscopist, naturalist, educator and lobbyist for science, is today almost a forgotten scientist whose life is celebrated only with a medal awarded by the Royal Society of Chemistry that honors achievement by younger chemists. In the 1870-80s, however, he invented a number of important synthetic dyestuffs including the cotton dyes isamine blue and Meldola's blue, and also naphthol green B, all of which have had application in biology and medicine. I describe here the early emergence of the synthetic dye industry, the first science-based industry, Meldola's role in its development, and his own inventions. Meldola's wide ranging achievements in science led to appointments as president of important professional scientific and manufacturers' societies. He was a fervent disciple of natural selection, a correspondent of Charles Darwin, and a prominent 19(th)-century neo-Darwinian. In 1886, drawing on analogies with evolutionary theory, he warned the British that neglect of science, particularly chemistry, would lead to industrial decline and even extinction, though his message generally was ignored, at least until 1914.  相似文献   

3.
4.
5.
The role of three histidine residues (His205, His296 and His303) and Asp259, important for the catalysis of NAD+-specific D-lactate dehydrogenase, was investigated using site-directed mutagenesis. None of these residues is presumed to be involved in coenzyme binding because Km for NADH remained essentially unchanged for all the mutant enzymes. Replacement of His205 with lysine resulted in a 125-fold reduction in kcat and a slight lowering of the Km value for pyruvate. D259N mutant showed a 56-fold reduction in kcat and a fivefold lowering of Km. The enzymatic activity profile shifted towards acidic pH by approximately 2 units. The H303K mutation produced no significant change in kcat values, although Km for pyruvate increased fourfold. Substitution of His296 with lysine produced no significant change in kcat values or in Km for substrate. The results obtained suggest that His205 and Asp259 play an important role in catalysis, whereas His303 does not. This corroborates structural information available for some members of the D-specific dehydrogenases family. The catalytic His296, proposed from structural studies to be the active site acid/base catalyst, is not invariant. Its function can be accomplished by lysine and this has significant implications for the enzymatic mechanism.  相似文献   

6.
7.
Abstract

This study concerns the fertility of Sherpa and Tibetan women living at altitudes over 3,400 meters in Nepal. The average completed fertility (4.77 live births) and estimated crude birth rate (31 to 33 per 1,000) are low relative to low altitude peasant populations as well as to high altitude Andean peasants. Environmental phenomena (hypoxia, iodine deficiency) may be associated with retarded menarchial age and high infant mortality; but the major factors causing the low fertility appear to be cultural rather than environmental. Traditional ceremonial requirements delay the age at marriage until the mid or late twenties. Religious practices promote male and female celibacy. Migrant females and women married to migrant males report reduced fertility, probably because of poor nutrition and health care. Nonmigrant women living in villages that participate extensively in the cash economy have greater access to the growing market economy, health care, and education and report higher numbers of live births and fewer child deaths.  相似文献   

8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
John H. Welsh came down from Boothbay, Maine in the late twenties and landed at Harvard. There he launched his academic career, raised a family, raised an additional family of graduate students and postdoctoral associates, and (with them all) shaped and cultivated diurnal rhythmicity, the biology of neurosecretion, and comparative neuropharmacology. After about 45 yr in the vineyards of Cambridge, he returned to Boothbay and his garden, tree-farm, grandchildren, writings and other good works.  相似文献   

18.
19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号