全文获取类型
收费全文 | 528篇 |
免费 | 32篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 23篇 |
大气科学 | 95篇 |
地球物理 | 108篇 |
地质学 | 197篇 |
海洋学 | 29篇 |
天文学 | 95篇 |
综合类 | 2篇 |
自然地理 | 13篇 |
出版年
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 25篇 |
2017年 | 29篇 |
2016年 | 56篇 |
2015年 | 28篇 |
2014年 | 38篇 |
2013年 | 31篇 |
2012年 | 18篇 |
2011年 | 23篇 |
2010年 | 28篇 |
2009年 | 28篇 |
2008年 | 15篇 |
2007年 | 22篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 5篇 |
1970年 | 3篇 |
1969年 | 4篇 |
1965年 | 4篇 |
1963年 | 2篇 |
排序方式: 共有562条查询结果,搜索用时 270 毫秒
271.
Within the framework of the Pan-European project about the geochemistry of bottled mineral waters in Europe launched in 2007 by the European Geological Surveys (EGS) Geochemistry Expert Group fourteen brands of bottled natural waters from Croatia of both mineral and spring types were evaluated for getting more coherent spatial information about the natural variation of element concentration in bottled waters found at the European market. Results of chemical analysis show that not a single one out of fourteen analyzed bottled waters from Croatia exceeds the Croatian water standards sanctioning thereby their suitability for human consumption. Also, statistical tests performed for 41 analytes (including pH and EC) clearly show that the water chemistry is in a high degree of conformity with regional geology, depending on structural, stratigraphic and, above all, lithological diversity of aquifers. Thus Dinaric and Pannonian parts of Croatia differ largely with regard to their water types: Dinaric region is completely lacking mineral water types while, on the other side, in the Pannonian region even the spring waters show stronger mineralization in comparison with their Dinaric counterparts. Typically, all natural waters from Croatia bear the bicarbonate (HCO3) signature. However, Ca–Mg cation pair combination is characteristic of spring waters while Na–K dominates in the mineral waters. 相似文献
272.
A visual basic spreadsheet macro for recession curve analysis 总被引:3,自引:0,他引:3
A Visual Basic program for an Excel spreadsheet was written to construct a master recession curve (MRC), using the adapted matching strip method, for recession analysis of ground water level time series. The program uses five different linear/nonlinear regression models to adjust individual recession segments to their proper positions in the MRC. The program can also be used to analyze the recession segments of other time series, such as daily stream discharge or stage. Some examples of field data from Croatia are used to illustrate the usefulness of its application. 相似文献
273.
Milan S. Dimitrijević 《Astrophysics and Space Science》1997,252(1-2):415-422
Results of an effort to provide to astrophysicists and physicists a set of Stark broadening parameters that is as complete as possible are presented. Such parameters are needed for stellar opacity calculations, stellar atmosphere modelling, abundance determinations, and diagnostics of various plasmas in astrophysics, physics, and plasma technology. The Stark broadening was treated using a semiclassical perturbation and modified semiempirical approaches. 相似文献
274.
D. Maričić B. Vršnak M. Dumbović T. Žic D. Roša D. Hržina S. Lulić I. Romštajn I. Bušić K. Salamon M. Temmer T. Rollett A. Veronig N. Bostanjyan A. Chilingarian B. Mailyan K. Arakelyan A. Hovhannisyan N. Mujić 《Solar physics》2014,289(1):351-368
We study heliospheric propagation and some space weather aspects of three Earth-directed interplanetary coronal mass ejections (ICMEs), successively launched from the active region AR 11158 in the period 13?–?15 February 2011. From the analysis of the ICME kinematics, morphological evolution, and in situ observations, we infer that the three ICMEs interacted on their way to Earth, arriving together at 1 AU as a single interplanetary disturbance. Detailed analysis of the in situ data reveals complex internal structure of the disturbance, where signatures of the three initially independent ICMEs could be recognized. The analysis also reveals compression and heating of the middle ICME, as well as ongoing magnetic reconnection between the leading and the middle ICME. We present evidence showing that the propagation of these two, initially slower ICMEs, was boosted by the fastest, third ICME. Finally, we employ the ground-based cosmic ray observations, to show that this complex disturbance produced a single cosmic ray event, i.e., a simple Forbush decrease (FD). The results presented provide a better understanding of the ICME interactions and reveal effects that should be taken into account in forecasting of the arrival of such compound structures. 相似文献
275.
Zlatko Majlinger Zoran Simić Milan S. Dimitrijević 《Journal of Astrophysics and Astronomy》2015,36(4)
The electron-impact widths for 27 Lu III spectral lines have been calculated by using the modified semiempirical method. Calculations have been also performed with the published relativistic Hartree-Fock oscillator strengths and additionally, with the approximate formula of Cowley. With the obtained results, the influence of Stark broadening on Lu III lines was investigated in the spectra of A-type stars. The obtained data will be included in the STARK-B database, which is part of the Virtual Atomic and Molecular Data Center – VAMDC. 相似文献
276.
T. Šilović Z. Ljubešić H. Mihanović G. Olujić S. Terzić Ž. Jakšić D. Viličić 《Estuarine, Coastal and Shelf Science》2011
Picoplankton distribution at the boundary zone of the southern Adriatic in May 2009 on a 75 km long shelf-continental slope transect was assessed by combining epifluorescence microscopy, flow cytometry and high-performance liquid chromatography data with hydrographic observations. The picoplankton distribution was greatly influenced by the hydrographic conditions prevailing in the southern Adriatic because of the influence of the Levantine Intermediate Water (LIW) and East Adriatic Current (EAC) forcing. Heterotrophic bacteria numerically dominated the picoplankton community through the entire transect with no significant accumulation. By contrast, picophytoplankton accumulated in the 50–75 m layer, forming a pronounced deep chlorophyll maximum. Synechococcus dominated the photosynthetic picoplankton, whereas picoeukaryotes were the least abundant. The intrusion of warm LIW observed in the layer between 100 and 350 m was followed by Prochlorococcus and Synechococcus peaks (10 × 103 cells mL−1 and 90 × 103 cells mL−1, respectively), as well as by the appearance of two Synechococcus ecotypes. Most picoeukaryotes were observed at the offshore stations, where geostrophic current calculation revealed the strongest EAC influence. A strong EAC spread over the central and eastern basin created a barrier for Prochlorococcus, whereas the picoeukaryote maxima coincided with the core of the EAC, suggesting its persistence to hydrological instabilities. 相似文献
277.
S. Matić-Skoko N. StagličićA. Pallaoro M. KraljevićJ. Dulčić P. TutmanB. Dragičević 《Estuarine, Coastal and Shelf Science》2011
Artisanal fisheries throughout the Mediterranean region are managed mostly by applying gear specific regulations. The data about the extent and dynamics by which littoral fish resources respond to commonly proposed changes of such regulations are lacking. Here the results of a 15 year (1995–2009) monitoring programme of littoral fish resources in a pilot region of island Vis aquatorium, central Adriatic Sea, are reported with the scope of investigating whether a more restrictive fishing regime (encompassing an increase in minimum inner layer mesh size of trammel net from 28 to 40 mm and excluding the trammel net from subsistence artisanal fishing) that has progressively been put in place during the study period has been accompanied by expected positive changes of littoral fish resources’ abundance, biomass and structure. Significant increases over time were observed in most of the community indices analyzed (abundance and biomass catch per unit effort, diversity indices) as well as a directional change in abundance and biomass catch composition of littoral fish resources. Positive responses were, however, primarily related with a recovery of Mullus surmuletus stock. Additionally, time-series analysis of ABC curves and their corresponding W index revealed that fish community in the study area was still moderately disturbed. Limited extent of conventional management restorative potential is further exacerbated by social issues – noncompliant behavior mainly among subsistence artisanal fishers and consequent resentment of commercial artisanal fishers. In order to improve further the state of the resources a more comprehensive set of management measures incorporating closed areas and a new approach actively involving fishers in the management process should be adopted. 相似文献
278.
Solar Physics - Observational data clearly indicate the presence of 3-min oscillations in sunspots in spectral lines covering a vast temperature range from the low chromosphere to those lines... 相似文献
279.
Gojko Djurašević 《Astrophysics and Space Science》1993,206(1):119-127
The paper is devoted to the actual problematics in the determination of orbital and physical parameters of active CB on the basis of the interpretation of photometric observations. One solves the problem in two stages: by obtaining a synthetic light curve in the case when the parameters of the corresponding CB model are given a priori (direct problem) and by determining the parameters of the given model for which the best fit between the synthetic light curve and the observations is achieved (inverse problem). In this paper, the above procedure is applied to a particular case of CB AG Vir. 相似文献
280.