全文获取类型
收费全文 | 10597篇 |
免费 | 824篇 |
国内免费 | 177篇 |
专业分类
测绘学 | 416篇 |
大气科学 | 954篇 |
地球物理 | 4049篇 |
地质学 | 3918篇 |
海洋学 | 474篇 |
天文学 | 1146篇 |
综合类 | 216篇 |
自然地理 | 425篇 |
出版年
2022年 | 50篇 |
2021年 | 119篇 |
2020年 | 109篇 |
2019年 | 86篇 |
2018年 | 672篇 |
2017年 | 605篇 |
2016年 | 595篇 |
2015年 | 403篇 |
2014年 | 381篇 |
2013年 | 469篇 |
2012年 | 903篇 |
2011年 | 654篇 |
2010年 | 352篇 |
2009年 | 379篇 |
2008年 | 310篇 |
2007年 | 251篇 |
2006年 | 271篇 |
2005年 | 940篇 |
2004年 | 962篇 |
2003年 | 757篇 |
2002年 | 259篇 |
2001年 | 160篇 |
2000年 | 134篇 |
1999年 | 68篇 |
1998年 | 90篇 |
1997年 | 87篇 |
1996年 | 53篇 |
1995年 | 72篇 |
1994年 | 83篇 |
1993年 | 48篇 |
1992年 | 47篇 |
1991年 | 51篇 |
1990年 | 67篇 |
1989年 | 48篇 |
1988年 | 42篇 |
1987年 | 40篇 |
1986年 | 43篇 |
1985年 | 46篇 |
1984年 | 37篇 |
1983年 | 46篇 |
1982年 | 50篇 |
1981年 | 43篇 |
1980年 | 46篇 |
1979年 | 40篇 |
1978年 | 51篇 |
1977年 | 42篇 |
1975年 | 44篇 |
1974年 | 31篇 |
1973年 | 45篇 |
1971年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
571.
572.
573.
Zusammenfassung Es wird der Einfluss des sogenannten Vorticity-Zentrums auf die Grenzfläche zweier Luftmassen der mittleren geographischen Breiten studiert. Zwecks Aufklärung der Rolle des Bewegungs- und Druckfeldes in diesem Prozesse wurde ein einfaches Modell konstruiert und numerisch gelöst. Die sich entwickelnde frontale Welle kann beziehungsweise als ein Anfangswert beim Lösen der mit der Stabilität der Wellen verbundenen Probleme mittels der Gleichungen, linearisiert durch die Methode der kleinen Störungen, dienen. Bei der Konstruktion des Modells wird ausser anderem von der Geometrie der Bewölkung ausgegangen, wie sie auf den Aufnahmen der meteorologischen Satelliten erfasst ist. 相似文献
574.
Břetislav Beránek Milica Mayerová Milada Zounková Alexander Guterch Rufin Materzok Jan Pajchel Reviewer J. Vaněk 《Studia Geophysica et Geodaetica》1973,17(3):205-217
Summary The paper deals with the results of DSS measurements along international profile VII, carried out by Czechoslovak and Polish geophysicists in 1970 – 71. The profile situation is shown in Fig. 1. By 1971 part of the profile in the region of the Bohemian Massif between points 1 and 3 and in Poland between points 5 and 7 had been surveyed (Fig. 2). The seismograms were used to construct the travel-time curves of the fundamental types of waves PK, PM, Pn (Fig. 4). The mean velocities were computed from the travel-time curves of the reflected waves (PM and PK) and the refracted waves (Pg). Isolines of the mean velocities could be constructed for the region of the Bohemian Massif (Fig. 6). The velocity data found were used for the depth interpretation of the travel-time curves of the principal types of waves and to construct a seismic section (Fig. 8). In the region of the Pre-Sudeten block the thickness of the crust was found to be 34–37 km, and in the Sudeten it increased to 40 km. Towards the south the thickness of the crust gradually reduces to 30 km in the system of the Luice faults. In the Bohemian Cretaceous the thickness of the crust is about 30 km. Further to the south, in the region of the Moldanubicum, the thickness of the Earth's crust increases rapidly, and at the southern border of the Central Bohemian pluton it reaches values of about 42 km. 相似文献
575.
Zdenka Schenková 《Pure and Applied Geophysics》1973,109(1):1700-1711
Summary The time distribution of earthquake occurrence in the European area is investigated by statistical laws. The original data of shallow-focus earthquakes are taken from the European catalogue 1901–1967. Evidence is given that the process with the negative binomial entries as a model describing the occurrence of shallow-focus earthquakes is better than the Poisson process. Further, the influence of magnitude classes and magnitude threshold value on the time distribution of earthquake occurrence is examined.Communication presented at the XIII General Assembly of the European Seismological Commission in Brasov in 1972. 相似文献
576.
Ota Kulhánek 《Pure and Applied Geophysics》1973,109(1):1653-1671
Summary The Uppsala seismograph array station (UPSAS) has been tested with respect to mutual resemblance of body-wave signals recorded by the individual array sensors. Records ofP-, pP- andPKP-phases from ten teleseismic earthquakes and the HANDLEY explosion, in the magnitude range fromm
b
=5.8 tom
b
=6.9, are investigated in detail. Calculated coherence and cross-correlation functions confirm that the area selected for UPSAS provides extremely favourable conditions for the operation of an array station. High signal similarity across UPSAS shows no obvious dependence upon the location of the focus or the magnitude. Natural and man-made events provide comparable results. 相似文献
577.
Václav Bucha Josef Horáček Reviewer A. Janáčková 《Studia Geophysica et Geodaetica》1973,17(4):321-336
Summary The paper brings a brief geological asessment of the sedimentational cycles, analyses the methods of collection and investigation of samples and the representativeness of the results obtained. Problems of magnetic cleaning and the types of demagnetization curves investigated are discussed. The continuous nature of the variations of the magnetic declination, inclination and remanent magnetization, determined by palaeomagnetic investigation of Quaternary sediments, is also discussed. The conclusion contains the principal facts about the dynamics of the geomagnetic field in the Quaternary and points out the possibility of applying them to the theory of the geomagnetic field, as well as to geological correlations. 相似文献
578.
Summary The paper gives a simple method for the reduction of Gravity observations with electronic computer. The major part of the gravity reductions is the computation of the correction for the far zones. This process was so simplified, that all far zone correction parameters depend on the topography can be determined — independent of the gravity measurement — for the whole survey area in one computer run (subprogram). The computed gravity data will be stored for plotter or other programs.
Zusammenfassung Die Arbeit gibt eine einfache Methode für die Reduktion gravimetrischer Meßdaten mit elektronischer Rechenmaschine. Den größten Teil der Reduktion von gravimetrischen Meßdaten machen die Korrektionen für die fernen Zonen aus. Diese Prozedur wurde so vereinfacht, daß man alle — von der Topographie abhängigen — Parameter der Fernzonenkorrektur, unabhängig von den gravimetrischen Me\daten, für das ganze Meßgebiet in einem Rechenprozeß berechnen kann. Die reduzierten gravimetrischen Meßdaten werden für Plotter oder andere Programme eingespeichert.相似文献
579.
Tibor Boldizsár 《Pure and Applied Geophysics》1967,67(1):128-132
Summary Latest measurements of terrestrial heat flow in the Hungarian and Russian parts of the Carpathian basin confirm previously measured high flow values between 2.0–3.3 cal/cm2 sec. Recent measurement in the Permian anticline structure of the Mecseck. Mts. in Hungary gave 2.4 cal/cm2sec, whereas in the Russian part of the basin, near to the Hungarian border 2.6 cal/cm2 sec was measured in Miocene sediments. For more than 100000 km2 surface of the Carpathian basin covered by Hungary and parts of Slovakia and Russian the high heat flow is an established fact. 相似文献
580.
The main structural-lithological factors responsible for the localization of hydrothermal mineralization on a regional, as well as on a local scale in the metallogenic province of western Cuba are summarized. The supply function of regional fault structures extending towards depth is emphasized and light is thrown on the localization of hydrothermal veins in fissures of the folded San Cayetano Formation. Stress has been laid on the genetic and chronological independence of pyrite bodies and hydrothermal veins. Six mineralization stages have been defined and their general succession in the metallogenic area under consideration has been determined.
Resumen Los factores principales litológico-estructurales, que causan la predisposición de la localización de los yacimientos hidrotermales en las dimensiones regionales y locales en la region de Cuba occidental, están sumarizados. La importancia de las dislocaciones regionales para el aporte de las soluciones hidrotermales está subrayada y las causas de la localización de las vetas hidrotermales en las ac-grietas de la formacion plegada de San Cayetano están aclaradas. La independencia genética y cronológica de los cuerpos de pirita y de las vetas hidrotermales polimetálicas está discutida. Seis estados de la mineralización hidrotermal están identificados y la succesión de la validez general para toda la region metalogenética de Cuba occidental está construida.相似文献