首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6125篇
  免费   238篇
  2023年   27篇
  2020年   85篇
  2019年   121篇
  2018年   409篇
  2017年   367篇
  2016年   407篇
  2015年   144篇
  2014年   129篇
  2013年   1394篇
  2012年   143篇
  2011年   291篇
  2010年   324篇
  2009年   186篇
  2008年   194篇
  2007年   172篇
  2006年   107篇
  2005年   96篇
  2004年   86篇
  2003年   82篇
  2002年   84篇
  2001年   94篇
  2000年   65篇
  1999年   58篇
  1998年   53篇
  1997年   65篇
  1996年   37篇
  1995年   49篇
  1994年   48篇
  1993年   50篇
  1992年   50篇
  1991年   38篇
  1990年   37篇
  1989年   19篇
  1988年   49篇
  1987年   42篇
  1986年   40篇
  1985年   53篇
  1984年   61篇
  1983年   57篇
  1982年   49篇
  1981年   54篇
  1980年   44篇
  1979年   45篇
  1978年   43篇
  1977年   36篇
  1976年   43篇
  1975年   23篇
  1974年   32篇
  1973年   22篇
  1972年   24篇
排序方式: 共有6363条查询结果,搜索用时 15 毫秒
71.
72.
73.
Several samples of geological stones from statuary pedestals found in various archaeological sites in Cyprus have been characterized using non-contact laser infrared photothermal radiometry. Thermal diffusivities and effective optical absorption coefficients were calculated using a one-dimensional thermal-wave model. The mean values and standard deviations were tabulated and comparisons were made with lithographic and petrographic studies of the samples. Good correlations were found, thus demonstrating that laser photothermal archaeometry is a promising methodology for the accurate, potentially non-destructive and convenient characterization of the origins of ancient stones in Cyprus and other geological and archaeological sites.  相似文献   
74.
David Schmid 《对极》1995,27(3):242-269
Radical geographers often discuss how contemporary urban space is becoming increasingly violent and dangerous. They pay much less attention to the question of how to make this space safe. In contrast, detective fiction focuses precisely on how to take danger out of the city. It therefore provides radical geographers with imaginative models of how different levels of space are linked through forms of violence. Detective fiction challenges accounts of the urban spatialization of power that over-simplify relations between city inhabitants as a clash between “oppressor” and “oppressed.” By suggesting how a subject can simultaneously oppress through and be oppressed by volence, detective fiction shows the contradictory multiplicity of people's spatial identifications.  相似文献   
75.
The localization or representation of mental abilities in the brain have always been considered as key questions for understanding the organization of the human nervous system. Particularly with the advent of modern electrophysiological and imaging techniques that provide maps of electromagnetic fields and metabolic processes on the living central nervous system, the representation theory is experiencing a scientific renaissance in neurology, but is only one theory, however, in the succession of a long philosophical tradition dealing with the possible identification of mental phenomena and brain processes. This dichotomy was formulated at the latest in the Cartesian dualism of res cogitans and res extensa of the mind-body problem. Nowadays philosophical discussion, on the contrary, is dominated by monistic concepts that attempt to explain the mental realm on an organic foundation in order not to succumb to the problem of a psychophysical dualism. Of these, the identity theory offers a philosophically plausible concept postulating that the identity of brain conditions and mental phenomena is based on organic foundations. In this theory, the efforts of brain research converge on the representations of mental phenomena in the human nervous system. In a comprehensive approach, both concepts could complement each other.  相似文献   
76.
77.
The need for experiments to study physical aspects of craft of the past is stated, as well as the necessity for them to have clear aims and to follow the established principles of scientific enquiry. These principles are discussed in this joint paper by ten maritime archaeologists and others, together with methods and some points of management critical to their application in this field.  相似文献   
78.
79.
Random Time Sampling is an innovative data collection method which has potential for adaptation and use by geographers. Individual pocket-sized programmable beepers were used in a pilot study of the uses of time by older households and older people's attitudes to different activities. Random beeps were used to prompt individuals living in eleven Melbourne suburbs to record time use data in diaries over a period of a week. The method proved extremely effective and reliable, and many participants reporting that they enjoyed the exercise.  相似文献   
80.
A trial, monitored release on the Wingecarribee River over 27 days had a peak discharge below the Wingecarribee Dam of 1090 ML/d, which had a flow duration of 0.95 per cent. Morphological impacts on 29 km of channel below the dam included bank erosion, concentrated neck overflow, bed degradation and channel widening at recent cutoffs, sedimentation in weir pools and overbank flow, particularly at discharges greater than 800 ML/d. Prolonged operational releases at bankfull discharge (400–800 ML/d) will have the greatest morphologic impacts and should be avoided. Pulses which dissipate stream power over a broad, well-vegetated floodplain should be incorporated in the operational release policy, provided such pulses are phased to facilitate channel and vegetation recovery.  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