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   1298篇
  免费   31篇
  国内免费   2篇
测绘学   52篇
大气科学   62篇
地球物理   613篇
地质学   307篇
海洋学   31篇
天文学   238篇
综合类   3篇
自然地理   25篇
  2018年   29篇
  2017年   32篇
  2016年   57篇
  2015年   33篇
  2014年   49篇
  2013年   55篇
  2012年   23篇
  2011年   33篇
  2010年   46篇
  2009年   41篇
  2008年   34篇
  2007年   31篇
  2006年   31篇
  2005年   13篇
  2004年   24篇
  2003年   19篇
  2002年   30篇
  2001年   26篇
  2000年   22篇
  1999年   15篇
  1998年   19篇
  1997年   17篇
  1996年   31篇
  1995年   23篇
  1994年   24篇
  1993年   33篇
  1992年   21篇
  1991年   16篇
  1990年   16篇
  1989年   25篇
  1988年   18篇
  1987年   22篇
  1986年   21篇
  1985年   19篇
  1984年   18篇
  1983年   24篇
  1982年   21篇
  1981年   15篇
  1980年   20篇
  1979年   20篇
  1978年   26篇
  1977年   24篇
  1976年   17篇
  1975年   17篇
  1974年   13篇
  1973年   17篇
  1972年   12篇
  1971年   20篇
  1970年   11篇
  1969年   13篇
排序方式: 共有1331条查询结果,搜索用时 390 毫秒
81.
Summary Phase velocities of Rayleigh and Love waves have been measured between the broadband seismic stations KHC (Kaperské Hory, South Bohemia) and KSP (Ksi, Lower Silesia), a profile that nearly coincides with the Interactional DSS Profile VII. The data for both wave types were separately inverted into models of shear-wave velocity versus depth. Novotný's model KHKS 82[1] for the DSS Profile VII was used as a start model. While the crustal section of Novotný's model is compatible with both of our data sets, our Rayleigh-wave data require smaller shear-wave velocities, on the average by 0.24 km/s, in the top 180 km of the mantle. The average difference between Novotný's model and our Love-wave model in that depth range is only 0.06 km/s. If our identification of the observed Love waves as the fundamental mode is correct, this result indicates the presence of polarization anisotropy in the uppermost mantle.
u a mu u a ¶rt; unu uuu mauu (an , a u) u S (, ua uu). u - S nuuum mmmm ¶rt;a¶rt; nu VII . a ¶rt; u mun m¶rt; umua ¶rt;u auumu mu nn mu. am mam¶rt;u a unaa ¶rt; S 82 m[1] ¶rt; nu VII . a am ¶rt;u m aua uu aau au ¶rt;a, ¶rt;a au ¶rt;a ¶rt; mm uu m nn — ¶rt; a 0,24 / 180 uma amuu. ¶rt;a aua ¶rt; ¶rt; m u a ¶rt; ¶rt; a m ¶rt;uanau n¶rt;mam 0,06 /. u aa u¶rt;muuau a¶rt;a a a ¶rt;ama ¶rt;a m nau, m mm mam u¶rt;ummm numuu nuau aumnuu amuu.
  相似文献   
82.
Mafic metavolcanic rocks in the area of the Zlaté Hory massive sulfide deposits are interpreted as convergent plate-margin basalts and basaltic andesites metamorphosed to the greenschist facies. According to the major- and trace-element compositions the metabasites exhibit island-arc tholeiitic to low-K, calc-alkaline composition.Approximately 50% of samples of maifc metavolcanics studied have a salient negative anomaly of Ce in chondrite-normalized REE patterns. The Ce-depleted greenschists are thought to represent hydrothermally altered equivalents of metabasites of island-arc tholeiitic composition. The alteration was accompanied by the sulfide mineralization. That is indicated by enrichment in Ba and S together with correlation of the Ce/Ce* values and CO2 abundances in the Ce-depleted rocks. The Ce anomaly may be caused by alteraton of ore-forming, seawaterderived solutions. The occurrence of Ce-depleted greenschists supports the hypothesis of the volcanogenic origin of the ore deposits in the Zlaté Hory area.  相似文献   
83.
au uu nu a¶rt;u a amma a nu¶rt; 1966–1981 naa, m ¶rt;, auu m m, u nu u ¶rt; uu n n¶rt;, ¶rt;num nu aa ¶rt; ¶rt;a n n¶rt;. m uu aa ¶rt;u u mu u.  相似文献   
84.
aam mam uu mn¶rt;muaamuu n¶rt; u u nua ua —aam auumu m mnam (200–1000°, 2 10–1 a). aa¶rt;u, m um na¶rt;a uu a n¶rt;u auumu mn¶rt;mu m mnam, u¶rt;m auumu ¶rt;a mn¶rt;mu mnam u n¶rt;m mu mnam uma.  相似文献   
85.
au a u naam u a nu¶rt; 1963–1973 . naam, m aum mun ma m mm nam aum n (II) na¶rt;am m u a uu ¶rt; u u,¶rt; ua ma u¶rt;, u u¶rt;a ma mn muna. mu u m ¶rt;u mam nm nmum n¶rt;auma amu m m mm II u a¶rt; ¶rt; n.  相似文献   
86.
Summary The time development of three large sequences, Friuli 1976, Thessaloniki 1978 and Monte Negro-Albania 1979, was investigated by analysing the characteristics of the time distribution of magnitudes of the events, M(t), of average magnitudes, (t), and of the number of events, n(t), as well as the strain release curves and the magnitude-frequency relations, N(M). The existence of time gaps and of an anomalous decay of the numbers of shocks before major events, as well as the oscillation of ( const b–1) may be considered as precursory phenomena. The clustering of events has been tested by the Poisson and negative binomial laws.Communication presented at the XVIIth General Assembly of the European Seismological Commission in Budapest, 21–29 August, 1980 under the title Properties of Seismic Regime and Recent Earthquake Sequences in Europe.  相似文献   
87.
88.
89.
Summary With the aid of 36 monthly and a double 12-month running average, graphs of the smoothed run of geomagnetic activity were constructed from the monthly values of the geomagnetic activity index aa for the period 1868–1978 and they were then used to determine the run of the geomagnetic activity, expressed during a uniform period and devoid of the secular variation of geomagnetic activity, for the individual 11-year cycles Nos 12–20 and the average runs for even and odd cycles, as well as for the whole period of the 9 cycles. The analysis and comparison of the graphs substantiates and renders more accurate the tendency, observed earlier, towards a regular alternation of geomagnetic activity cycles with double and single maxima. Wheareas a saddle-like shape with a maximum in the neighbourhood of the first and third quarter of the cycle is characteristic of the shape of the even cycle, the second maximum being, as a rule, the main one, the odd cycle is characterized by a peak-like shape with the main maximum in the vicinity of the cycle's centre.  相似文献   
90.
Zedník  J.  Pospíšil  J.  Růžek  B.  Horálek  J.  Boušková  A.  Jedlička  P.  Skácelová  Z.  Nehybka  V.  Holub  K.  Rušajová  J. 《Studia Geophysica et Geodaetica》2001,45(3):267-282
In the time span from January 1995 to December 1999 the Czech National Seismological Network (CNSN), consisting of ten permanent digital broadband stations, several local networks and two data centers, detected and recorded 9530 regional natural seismic events, 27 greater than magnitude 2. Most of these events were located by the Czech Seismological Service (CSS), and the most prominent of them were analyzed in detail. A large number of quarry blasts were recorded as well but were not included in the analysis. We provide basic information on the configuration of the CNSN and on the way of routine data processing employed by the CSS in this paper. The over-all regional seismicity monitored by the CNSN in 1995–1999 is briefly reviewed. The main results of observations and evaluation of the local (NW-Bohemia/Vogtland, South Bohemia, Sudeten) and induced (Kladno, Píbram, Upper Silesia, Lubin/Poland) seismic activity within this period are presented in a condensed form. Finally, a summary on macroseismic observations on the territory of the Czech Republic in 1995–1999 is also presented.  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