全文获取类型
收费全文 | 216篇 |
免费 | 8篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 6篇 |
地球物理 | 70篇 |
地质学 | 28篇 |
海洋学 | 11篇 |
天文学 | 64篇 |
自然地理 | 43篇 |
出版年
2021年 | 2篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 10篇 |
2012年 | 4篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 13篇 |
2006年 | 7篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1996年 | 2篇 |
1994年 | 5篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1966年 | 3篇 |
1965年 | 1篇 |
1952年 | 1篇 |
1951年 | 1篇 |
1949年 | 2篇 |
1932年 | 1篇 |
1926年 | 1篇 |
1922年 | 2篇 |
1920年 | 1篇 |
排序方式: 共有224条查询结果,搜索用时 31 毫秒
31.
32.
33.
34.
16 lines of Pr ii possibly present in the solar photospheric spectrum have been studied. When including hyperfine structure in synthetic calculations, investigations of 9 lines result in an abundance A
Pr = 0.71 ± 0.08 in the log A
H = 12.00 scale. 相似文献
35.
Ethnic coexistence in a pluralistic campus environment 总被引:1,自引:0,他引:1
Emile Kok-Kheng Yeoh 《GeoJournal》2006,66(3):223-241
In Malaysia, ethnic segregation seems to have grown more and more pronounced at all levels of education, which may have in
the main contributed to increasing occupational segregation by ethnicity when the graduates left to join the job market. Such
trends may be disturbing given the effort the country has put in to promote interethnic understanding and reduce interethnic
economic disparity since 1970. By critically investigating the dynamics of ethnic coexistence in the microcosm of the university
campus environment, this paper provides statistical evidence to show how far the country has progressed in terms of ethnic
relations since the watershed events of May 13, 1969; to what extent Malaysian multiethnic society is different now compared
to the unmistakable racial “corporateness” and interethnic “separateness” that Furnivall observed in his classic study of
1948; and in what ways ethnic relations have been reshaped by three decades of affirmative action policies and the form of
ethnic democracy adapted for this unique society.
相似文献
Emile Kok-Kheng YeohEmail: |
36.
Emmanuelle Vennin Anthony Bouton Raphaël Bourillot Aurlie Pace Adeline Roche Arnaud Brayard Christophe Thomazo Aurelien Virgone Eric C. Gaucher Guy Desaubliaux Pieter T. Visscher 《Sedimentology》2019,66(1):165-204
The Bonneville Basin is a continental lacustrine system accommodating extensive microbial carbonate deposits corresponding to two distinct phases: the deep Lake Bonneville (30 000 to 11 500 14C bp ) and the shallow Great Salt Lake (since 11 500 14C bp ). A characterization of these microbial deposits and their associated sediments provides insights into their spatio‐temporal distribution patterns. The Bonneville phase preferentially displays vertical distribution of the microbial deposits resulting from high‐amplitude lake level variations. Due to the basin physiography, the microbial deposits were restricted to a narrow shoreline belt following Bonneville lake level variations. Carbonate production was more efficient during intervals of relative lake level stability as recorded by the formation of successive terraces. In contrast, the Great Salt Lake microbial deposits showed a great lateral distribution, linked to the modern flat bottom configuration. A low vertical distribution of the microbial deposits was the result of the shallow water depth combined with a low amplitude of lake level fluctuations. These younger microbial deposits display a higher diversity of fabrics and sizes. They are distributed along an extensive ‘shore to lake’ transect on a flat platform in relation to local and progressive accommodation space changes. Microbial deposits are temporally discontinuous throughout the lake history showing longer hiatuses during the Bonneville phase. The main parameters controlling the rate of carbonate production are related to the interaction between physical (kinetics of the mineral precipitation, lake water temperature and runoff), chemical (Ca2+, Mg2+ and HCO3? concentrations, Mg/Ca ratio, dilution and depletion) and/or biological (trophic) factors. The contrast in evolution of Lake Bonneville and Great Salt Lake microbial deposits during their lacustrine history leads to discussions on major chemical and climatic changes during this interval as well as the role of physiography. Furthermore, it provides novel insights into the composition, structure and formation of microbialite‐rich carbonate deposits under freshwater and hypersaline conditions. 相似文献
37.
Emile Novel 《Aquatic Sciences - Research Across Boundaries》1949,11(3-4):546-550
Résumé L'eau de consommation délivrée actuellement à la population genevoise et d'une richesse en germes nettement plus élevée que
celle délivrée en 1893.
L'augmentation du nombre des microorganismes est due, avant tout, à la pollution des canalisations dans lesquelles le plancton
mort sert de substrat nutritif aux bactéries et leur permet de se multiplier dans l'eau des conduites.
Zusammenfassung Das Trinkwasser der Stadt Genf weist heute eine auffallend h?here Keimzahl auf als im Jahr 1893. Dies ist auf die Verschmutzung der Kanalisationen zurückzuführen. In ihnen finden die Bakterien im abgestorbenen Plankton ein günstiges N?hrsubstrat, so da? sie sich in den Wasserleitungen vermehren.相似文献
38.
Emile André 《Aquatic Sciences - Research Across Boundaries》1926,3(3-4):259-266
39.
40.
Daniel Bégin Rodolphe Devillers Stéphane Roche 《International journal of geographical information science》2018,32(8):1611-1630
Over the last two decades, online communities have become ubiquitous, with millions of people accessing collaborative project websites every day. Among them, the OpenStreetMap project (OSM) has been very successful in collecting/offering volunteered geographic information (VGI). Very different behaviours are observed among OSM participants, which translate into large differences of lifespan, contribution levels (e.g. Nielsen’s 90–9-1 rule) and attitudes towards innovations (e.g. Diffusion of innovation theory or DoIT). So far, the literature has defined phases in the life cycle of contributors only based on the nature of their contributions (e.g. role of participants and edits characteristics). Our study identifies the different phases of their life cycle from a temporal perspective and assesses how these phases relate to the volume and the frequency of the contributions from participants. Survival analyses were performed using both a complementary cumulative distribution function and a Kaplan-Meier estimator to plot survival and hazard curves. The analyses were broken down according to Nielsen and DoIT contributors’ categories to highlight potential explanatory variables. This paper shows that two contribution processes combine with three major participation stages to form six phases in contributors’ life cycle. The volume of edits provided on each active day is driven by the two contribution processes, illustrating the evolution of contributors’ motivation over time. Since contributors’ lifespan is a universal metric, our results may also apply to other collaborative online communities. 相似文献