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   145篇
  免费   21篇
  166篇
  2022年   1篇
  2021年   4篇
  2017年   1篇
  2016年   1篇
  2015年   5篇
  2014年   2篇
  2013年   1篇
  2012年   6篇
  2011年   3篇
  2010年   3篇
  2009年   9篇
  2008年   7篇
  2007年   9篇
  2006年   11篇
  2005年   9篇
  2003年   2篇
  2002年   2篇
  2001年   4篇
  2000年   5篇
  1999年   2篇
  1998年   7篇
  1997年   2篇
  1996年   1篇
  1995年   3篇
  1993年   2篇
  1992年   1篇
  1991年   8篇
  1990年   4篇
  1989年   1篇
  1988年   3篇
  1987年   8篇
  1986年   6篇
  1985年   3篇
  1984年   4篇
  1983年   4篇
  1982年   5篇
  1981年   4篇
  1980年   1篇
  1979年   1篇
  1978年   3篇
  1977年   1篇
  1973年   1篇
  1969年   1篇
  1968年   2篇
  1966年   1篇
  1965年   1篇
  1939年   1篇
排序方式: 共有166条查询结果,搜索用时 0 毫秒
31.
This paper examines the possible role of dreams and other forms of virtual worldmaking (chiefly fictions) in forming and maintaining our adaptive systems. I posit no exclusive function for the dream. Rather, I treat it a an extension of fiction's preoccupation with our daily concerns, desires and fears. I suggest that narratives help us to enlarge and revise our perceptual and response systems, not by offering us moral or ethical propositions to live by but by increasing certain skills in our mental organization. Departing from John Paulos' idea that fictions and mathematics (narratives and numbers) work in similar ways, I further examine the role that probability ratios might play in dreams, despite the seeming bizarreness of many dreams. The overall idea is that narratives of all sorts are one cognitive means, among many, by which we accumulate sums of knowledge and expectation, and maintain and revise our notions of what goes with what in human experience. I also look briefly at fictional archetypes (Oedipus, Orestes/Hamlet, etc.) and universal dreams (falling, being lost or attacked, etc.) as master plots in our probability systems.  相似文献   
32.
The relationship between weather and daily mortality was examined over a 4-year period in the temperate climate of Pittsburgh, Pennsylvania. Eight weather parameters were correlated with daily mortality using multiple, simple, and partial correlation techniques. Results from this study were then compared with results obtained from a previous investigation involving an identical analysis of the effects of weather on death in the subtropical climate of Birmingham, Alabama. Although the relationship between weather and total mortality is statistically significant in both areas, weather in the temperate region accounts for a greater portion of the daily variation in number of deaths. In both cities the effect of weather increases with age and is more intense among the white than the nonwhite population but does not appear to vary with sex. In both places weather significantly influences death due to respiratory diseases and circulatory diseases in general, but affects little, mortality from cancer or behaviorally related causes. The cities differ, however, in that Pittsburgh weather is significantly associated with deaths from ischemic heart disease but not with cerebrovascular mortality, while the reverse is observed in Birmingham. The cities also differ in specific meteorological factors and in the seasonal distribution of the intensity of the weather-mortality relationship.  相似文献   
33.
34.

Background  

The genetic control of floral organ specification is currently being investigated by various approaches, both experimentally and through modeling. Models and simulations have mostly involved boolean or related methods, and so far a quantitative, continuous-time approach has not been explored.  相似文献   
35.
Babesia microti and Borrelia burgdorferi, the respective causative agents of human babesiosis and Lyme disease, are maintained in their enzootic cycles by the blacklegged tick (Ixodes scapularis) and use the white-footed mouse (Peromyscus leucopus) as primary reservoir host. The geographic range of both pathogens has expanded in the United States, but the spread of babesiosis has lagged behind that of Lyme disease. Several studies have estimated the basic reproduction number (R 0) for B. microti to be below the threshold for persistence (<1), a finding that is inconsistent with the persistence and geographic expansion of this pathogen. We tested the hypothesis that host coinfection with B. burgdorferi increases the likelihood of B. microti transmission and establishment in new areas. We fed I. scapularis larva on P. leucopus mice that had been infected in the laboratory with B. microti and/or B. burgdorferi. We observed that coinfection in mice increases the frequency of B. microti infected ticks. To identify the ecological variables that would increase the probability of B. microti establishment in the field, we integrated our laboratory data with field data on tick burden and feeding activity in an R 0 model. Our model predicts that high prevalence of B. burgdorferi infected mice lowers the ecological threshold for B. microti establishment, especially at sites where larval burden on P. leucopus is lower and where larvae feed simultaneously or soon after nymphs infect mice, when most of the transmission enhancement due to coinfection occurs. Our studies suggest that B. burgdorferi contributes to the emergence and expansion of B. microti and provides a model to predict the ecological factors that are sufficient for emergence of B. microti in the wild.  相似文献   
36.
37.
PRIDE: the proteomics identifications database   总被引:2,自引:0,他引:2  
The advent of high-throughput proteomics has enabled the identification of ever increasing numbers of proteins. Correspondingly, the number of publications centered on these protein identifications has increased dramatically. With the first results of the HUPO Plasma Proteome Project being analyzed and many other large-scale proteomics projects about to disseminate their data, this trend is not likely to flatten out any time soon. However, the publication mechanism of these identified proteins has lagged behind in technical terms. Often very long lists of identifications are either published directly with the article, resulting in both a voluminous and rather tedious read, or are included on the publisher's website as supplementary information. In either case, these lists are typically only provided as portable document format documents with a custom-made layout, making it practically impossible for computer programs to interpret them, let alone efficiently query them. Here we propose the proteomics identifications (PRIDE) database (http://www.ebi.ac.uk/pride) as a means to finally turn publicly available data into publicly accessible data. PRIDE offers a web-based query interface, a user-friendly data upload facility, and a documented application programming interface for direct computational access. The complete PRIDE database, source code, data, and support tools are freely available for web access or download and local installation.  相似文献   
38.
Most current methods for gene regulatory network identification lead to the inference of steady-state networks, that is, networks prevalent over all times, a hypothesis which has been challenged. There has been a need to infer and represent networks in a dynamic, that is, time-varying fashion, in order to account for different cellular states affecting the interactions amongst genes. In this work, we present an approach, regime-SSM, to understand gene regulatory networks within such a dynamic setting. The approach uses a clustering method based on these underlying dynamics, followed by system identification using a state-space model for each learnt cluster—to infer a network adjacency matrix. We finally indicate our results on the mouse embryonic kidney dataset as well as the T-cell activation-based expression dataset and demonstrate conformity with reported experimental evidence.  相似文献   
39.
40.
The aim of the study was to evaluate anthropometric characteristics as determinants of 500 m rowing ergometer performance in physically inactive collegiate females. In this cross-sectional study, which included 196 collegiate females aged 19-23 years not participating in regular physical activities, body mass (BM), body height (BH), length of upper limbs (LA), length of lower limbs (LL), body mass index (BMI), slenderness index (SI), and the Choszcz-Podstawski index (CPI) were measured and a stepwise multiple regression analysis was performed. Participants performed 500 m maximal effort on a Concept II rowing ergometer. BM, BH, LA, LL, and the BMI, SI and CPI indices were found to be statistically significant determinants of 500 m performance. The best results (T) were achieved by females whose BH ranged from 170 to 180 cm, with LA and LL ranging from 75 to 80 cm and 85 to 90 cm, respectively. The best fitting statistical model was identified as: T = 11.6793 LR – 0.1130 LR2 – 0.0589 LN2 + 29.2157 CPI2 + 0.1370 LR·LN - 2.6926 LR·CPI – 211.7796. This study supports a need for additional studies focusing on understanding the importance of anthropometric differences in rowing ergometer performance, which could lead to establishing a better quality reference for evaluation of cardiorespiratory fitness tested using a rowing ergometer in collegiate females.  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