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 484 毫秒
1.
Systematic entomology flourished as a branch of Natural History from the 1750s to the end of the nineteenth century. During this interval, the “era of Heroic Entomology,” the majority of workers in the field were dedicated amateurs. This article traces the demographic and occupational shifts in entomology through this 150-year interval and into the early twentieth century. The survey is based on entomologists who studied beetles (Coleoptera), and who named sufficient numbers of species to have their own names abbreviated by subsequent taxonomists. In the eighteenth century, 27 entomologists achieved this level of prominence, of whom 37% were academics, 19% were doctors, 11% had private incomes, 19% were clergymen, and 8% were government officials. Many of those with private incomes were members of the European aristocracy, and all but one were European men. The nineteenth century list included 192 entomologists, of whom 17% were academics, 16% were museum curators, 2% were school teachers, 15% were doctors, 6% were military men, 7% were merchants, 2% were government entomologists, 6% had private incomes, 5% were clergymen, 5% were government officials, and 4% were lawyers. The demographics of entomology shifted dramatically in the nineteenth century. Whereas many of the noteworthy entomologists of the eighteenth century were German, Swedish, or French, in the nineteenth century, many more European countries are represented, and almost one-fifth of the noteworthy entomologists were from the United States. The nineteenth century list, like the eighteenth century list, contains no women. By the twentieth century, 63% of 178 noteworthy systematic entomologists were paid professionals, teaching entomology courses in universities, or studying insect taxonomy in museums and government-sponsored laboratories. Only one person on the twentieth century list had a private income, but women (ten individuals) were included on the list for the first time.  相似文献   

2.
In the late-Middle Ages and at the onset of the early modern period, the Dutch population was taller than in the first half of the 19th century. This inference is partially based on skeletal evidence, mainly collected by the Dutch physical anthropologist George Maat and his co-workers. A spectacular increase in Dutch heights began in the second half of the 19th century and accelerated in the second half of the 20th century. At the end of the 20th century, the Dutch became tallest in the world.  相似文献   

3.
R S Bray 《Parassitologia》1987,29(2-3):175-179
There exist records of what seems to be cutaneous leishmaniasis at least as far back as 650 BC, and possibly much earlier in the Tigris/Euphrates basin. It was described by Avicenna in the 10th century AD, and was well-known in Aleppo and Baghdad by the 18th century AD. Cutaneous leishmaniasis due to Leishmania infantum may have occurred in Crete in the 18th century. Artificial transmission was effected in Algeria and Aleppo in the 18th century.  相似文献   

4.
Dendrochronological studies are carried out on rural buildings in the French Alps for twenty years. In this contribution, we examine an extensive dataset of larch timbers (n = 1294) that were dendrochronologicaly dated at 139 buildings. This material yielded felling dates spanning the 11th century to the 20th century and contributed to improve our knowledge of human occupation and exploitation of mountain forests during the second millennium CE. From the 11th to the 14th century, rural populations increasingly exploited older forests. The crises of the 14th century led to a significant decrease in construction and by extension in tree cutting. The beginning of the 15th century marks a resumption of construction and felling which is continuous until the beginning of the 20th century. There is a relationship between the age of harvested trees, the number of dates and population fluctuations, which corroborates findings at the European scale. Regional trade probably influenced the stem diameters used in constructions in the immediate vicinity of the forests. Logging regulations can be perceived through variations in the age of harvested trees. The 14th century gap in felling dates would also mark a transition period in the exploitation of mountain forests and by extension a transformation of the economy.  相似文献   

5.
发展海岛旅游业的制约因素及对策   总被引:12,自引:0,他引:12  
白洁 《生态科学》2002,21(2):179-181
21世纪将是人类对海洋全面认识,充分利用,切实保护的新世纪。特别是作为这个世纪旅游新时尚的海岛旅游业的发展,正面临来自环境条件的诸多挑战。为进一步利用海洋资源,满足现代人追求人文生态的精神生活需求,只有在切实解决资金、生态、体制等制约瓶颈的基础上,探索可持续发展的战略思路,才能逐步实现海岛旅游由传统的海洋开发向现代的生态式海洋开发转变。  相似文献   

6.
To study natural polymorphism, pollen grains should be collected from ecologically clean sites. Taking the ecological conditions at the end of the 19th century and at the beginning of the 20th century as more favorable than the modern state, herbarium material (LE) was examined. In addition to typical (normally developed) pollen grains, we found two more morphological types within the range of natural polymorphism of pollen grains of Acer tataricum L. that were produced at the end of the 19th century and at the beginning of the 20th century.  相似文献   

7.
The study represents palaeodemographic research of osteological material of 3304 individuals from the funds of the Anthropological Laboratory of the Institute of History of the University of Latvia in Riga, dating from the 7th to the 18th century AD. Compensated life expectancy at birth is varying between 20.3 and 22.2 years during the research period. Crude mortality has changed between 49.3 and 45% per hundred. In the early period (7th-13th century) there is a significant male prevalence (2.2-1.4); female life expectancy at the age of 20 is on average 6.6 years less than for males. This difference decreases to 5.4 years in the 13th-18th century. According to historical demography, female life span exceeded male only in the 2nd half of 19th century. The palaeodemographic data indicate that in the 7th-18th century, women in Latvia gave birth to a mean of 4-5 children (the figure includes childless women), of whom half, at most 2-2.5, reached reproductive age, on account of high child mortality. The net reproductive rate R0 (the number of descendants per individual of the parents' generation) varies between 1 and 1.25 in the study period. Concerning the completely excavated cemeteries of Lejasbiteni (7th-10h century) and Daudziesi (16th-17th century), it was possible to calculate the size and structure of the populations that had used these cemeteries. They were similar, having 45.3-49.9% of children up to an age of 14 and 24-28% individuals over the age of 30. According to historical demography, radical improvement of the demographic situation in Latvia began in the second half of the 19th century, when the process of demographic transition in Latvia started.  相似文献   

8.
Vaccines have been one of the major revolutions in the history of mankind and, during the twentieth century, they eliminated most of the childhood diseases that used to cause millions of deaths. In the twenty-first century, vaccines will also play a major part in safeguarding people's health. Supported by the innovations derived from new technologies, vaccines will address the new needs of a twenty-first century society characterized by increased life expectancy, emerging infections and poverty in low-income countries.  相似文献   

9.
For the past 30 years, the Danish Wadden Sea area has been protected by fishery and hunting regulations, pollution controls and settlement restrictions. Nevertheless, todays Wadden Sea is a depleted ecosystem when we compare it with past abundance and diversity of marine animal populations. This review indicates that the abundance of finfishes has undergone a long-term decline since the seventeenth century. The review also indicates a trajectory of ecological decline since the early twentieth century that seems to be related to: (1) fishing extractions which focused on undersized fish throughout the first half of the twentieth century; (2) habitat destruction, which was most marked in the first half of the twentieth century; and (3) pollution, which was worst in the third quarter of the twentieth century. Historical investigation reveals that we need to fundamentally revise present-day baselines about the potential species richness and abundance of the Wadden Sea.  相似文献   

10.
走向21世纪的遗传学   总被引:1,自引:0,他引:1  
对一个世纪以来遗传学的发展史及其所取得的主要成就作了回顾,并对二十一世纪遗传学的发展趋势进行了展望。  相似文献   

11.
The isonymic method has been generally accepted in population genetic studies and surnames have been successfully used to investigate human populations as if they were genetic markers associated to the Y chromosome. In this study we analysed the microevolution dynamics of Postua, a mountain village of North Western Italy, by means of demographic methods. The uniqueness of this community is due to its past geographical and cultural isolation and to the high frequency of marriage between relatives. During the study period considered (1640–1989) the population underwent several fluctuations in size and other demographic parameters such as the endogamy, isonimy and consanguinity rates. Until the first half of the XIX century Postua appears to be a village characterised by a closed and isolated community, with high endogamy (80–90%) and isonimy (up to 34.4%). Only at the beginning of the XX century, when the population started to be subjected to significant immigration fluxes, data show a progressive reduction of the isolation. The population showed two demographic peaks, the first around the second half of the XVIII century (1639 inhabitants) and the second at the end of the XIX century (1464 inhabitants). The S/N ratio was low (0.2–0.3) and relatively constant until the beginning of the last century, and only in the last three decades of the XX century, when the population was subjected to immigration, Postua showed a significant increase in the S/N ratio values (to about 0.9). The surname frequency was constant until the 1850 when almost all surnames were the same as those already present in the XVII century. From the first half of the XIX century, the founder surnames decreased, whereas new surnames started to increase and became persistent in the population.  相似文献   

12.
The Black Death (1349–1350 in Norway) is often cited as the cause of a severe population decline and building hiatus in the middle of the 14th century. This paper analyses this hypothesis by matching the Black Death with human and environmental impacts on tree-ring growth. The number of buildings dated by dendrochronology in Norway shows a dramatic decline several decades before the plague. In Norway, the building hiatus, which has parallels in several other places in Europe, dates from the late-13th century almost to the 16th century. The first dated houses built after the plague date from the 15th century and many of the logs have exceptionally wide tree rings compared to timber from other periods. Assuming the rapid growth was because of an open landscape, the trees are likely to have grown on infields of farms abandoned due to the 14th century population decline. Since many of these fast-growing trees germinated in the early-14th century and the number of dated buildings drops dramatically several decades before the plague, the Black Death can hardly be the only reason for the population decline in Norway and one plausible explanation is that some environmental impact occurred decades earlier. The dendroclimatological evidence of cold and wet summers in the years before the plague is suggestive, but historical sources also pinpoint famine due to crop failure. They also tell of farms being abandoned several decades before the plague and mention periods of heavy rainfall and famine in the early-14th century.  相似文献   

13.
The article describes how the medical school in Montpellier, organized in 1498, responded to the development of the Jussiaean classification of plants. Though overshadowed by Paris in the eighteenth century as a center of medical and botanical training, botany as taught at Montpellier provided the impetus for the conversion of traditional herbalism into a biology-based medicine by the nineteenth century. In addition, the plant affinities and analogies underlying natural classification led to the conception of a viable theory of evolution, as Darwin acknowledged. The opposition to these advances, evident in the nineteenth century, remains alive today.  相似文献   

14.
This study attempts to address the issue of relative living standards in Portuguese medieval and early 20th century periods. Since the growth of children provides a good measure of environmental quality for the overall population, the skeletal growth profiles of medieval Leiria and early 20th century Lisbon were compared. Results show that growth in femur length of medieval children did not differ significantly from that of early 20th century children, but after puberty medieval adolescents seem to have recovered, as they have significantly longer femora as adults. This is suggestive of greater potential for catch-up growth in medieval adolescents. We suggest that this results from distinct child labor practices, which impact differentially on the growth of Leiria and Lisbon adolescents. Work for medieval children and adolescents were related to family activities, and care and attention were provided by family members. Conversely, in early 20th century Lisbon children were more often sent to factories at around 12 years of age as an extra source of family income, where they were exploited for their labor. Since medieval and early 20th century children were stunted at an early age, greater potential for catch-up growth in medieval adolescents results from exhausting work being added to modern adolescent's burdens of disease and poor diet, when they entered the labor market. Although early 20th century Lisbon did not differ in overall unfavorable living conditions from medieval Leiria, after puberty different child labor practices may have placed modern adolescents at greater risk of undernutrition and poor growth.  相似文献   

15.
The genius of Indian paintings was first manifested in the Ajantan mural art which spanned a whole millennium from the second century B.C. to the eighth century A.D. This rich tradition, which continued up to the nineteenth century under the patronage of different dynasties in India, declined by the end of that century. But this cultural heritage has been kept alive by a few artists in Kerala who practice even today the methods and techniques of mural paintings similar to those practiced by the Ajantan mural painters. Plant materials and/or plant products used during different phases of a mural painting, from preparation of the base wall to the finishing touches of the creation are identified and pro-cessing and application detailed. Ajantan and post-Ajantan murals are reviewed and the ma-terials, methods and techniques used in them are discussed.  相似文献   

16.
This article presents a fossil diatom-based, semi-quantitative reconstruction of water level fluctuations for Lake Baringo over the past 200 years as a consequence of climatic variations. A 285 cm long sediment core sample was collected using a Rod-Operated Single-drive Stationary Piston corer. Lake level was inferred using indices based on the proportion of planktonic to benthic diatom taxa (P/B ratio). The sediment archive presented distinct zones dominated by planktonic and benthic diatom flora. An initial transgression in the early 19th century was characterised as a shallow water environment dominated by planktonic Aulacoseira spp. This was a response to extreme drought during the late 18th to early 19th century. Mid-19th century was defined by a high lake stand. The late 19th to early 20th centuries experienced low water level following the widely documented aridity at the time. The mid-20th century was marked by a spectacular rise in water level that coincided with remarkably wet years during the early 1960s and late 1970s. The first decade of the 21st century witnessed widespread changes in water level. The proxy records show that lake ramping and drawdown over the years follow approximately 50-year climatic cycles.  相似文献   

17.
The expected decline of health indicators with economic recessions and improvement with economic growth in the nineteenth century Sweden was reversed in the twentieth century, giving the counterintuitive pattern of higher mortality and lower life expectancy in economic expansions and improvement of these indices in recessions. The change or “tipping point” occurred at the end of the nineteenth century or early in the twentieth century when electrification was introduced into Sweden. All 5 of the reversals of annual industrial electric energy use in the US between 1912 and 1970 were accompanied by recessions with lowered GDP, increased unemployment, decreased mortality and increased life expectancy. The health indices were not related to residential electricity use. The mortality improvement between 1931 and 1932 by state in the US strongly favored urban areas over rural areas. Rural unemployment by state in 1930 was significantly positively correlated with residential electrification percentage by state in 1930. The health effects of economic change are mediated by electrical exposure.  相似文献   

18.
19.
Lichens are thought to be sensitive indicators of global warming, as the spread of several thermophilous epiphytes in north-western Central Europe has been attributed to late 20th century warming. In the present paper, the potential contribution of late 20th century warming to the decline of arctic-alpine and boreal-montane lichen species is analyzed. Relevant ecological groups of lichens include terricolous heathland species, saxicolous species of exposed rock outcrops and boulder fields as well as epiphytes of mountain forests. These three groups of lichens experienced significant declines before the onset of late 20th century warming in the 1970s. These declines can be attributed to the abandonment of traditional land use systems in the case of the heathland lichens, increased recreational use of the exposed summits usually inhabited by cold-tolerant saxicolous lichens, and to high atmospheric SO2 levels in the mid-20th century, but are probably not directly connected to global warming.  相似文献   

20.
许再富 《生物多样性》2000,8(1):112-119
根据有关历史资料的统计分析,在元朝以后,滇南各土司向天朝上贡的犀角估算有79~123支,并在清朝于18世纪末19世纪初犀牛就成为濒于灭绝的物种,而最后的一头犀牛是在1957年在滇南被捕杀。滇南各土司在元朝以后向天朝上贡的大象估算有1140~1339头、象牙38~76支,加上大象和犀牛被用于频繁的战争,它在17世纪中期就处于濒危的状态。因而,向天朝上贡这一特殊的人文因素是大象和犀牛在滇南濒危和灭绝的重要原因之一。虽然犀牛已在滇南灭绝,但从现代的生态环境来说,实现再引种是可能的。  相似文献   

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