全文获取类型
收费全文 | 5364篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 16篇 |
大气科学 | 1008篇 |
地球物理 | 1221篇 |
地质学 | 3046篇 |
海洋学 | 22篇 |
天文学 | 17篇 |
综合类 | 3篇 |
自然地理 | 35篇 |
出版年
2013年 | 53篇 |
1998年 | 26篇 |
1997年 | 33篇 |
1996年 | 73篇 |
1995年 | 43篇 |
1994年 | 39篇 |
1993年 | 58篇 |
1992年 | 146篇 |
1991年 | 152篇 |
1990年 | 139篇 |
1989年 | 134篇 |
1988年 | 136篇 |
1987年 | 173篇 |
1986年 | 129篇 |
1985年 | 114篇 |
1984年 | 151篇 |
1983年 | 168篇 |
1982年 | 183篇 |
1981年 | 183篇 |
1980年 | 151篇 |
1979年 | 185篇 |
1978年 | 159篇 |
1977年 | 149篇 |
1976年 | 116篇 |
1975年 | 139篇 |
1974年 | 125篇 |
1973年 | 141篇 |
1972年 | 129篇 |
1971年 | 137篇 |
1970年 | 143篇 |
1969年 | 100篇 |
1968年 | 130篇 |
1967年 | 123篇 |
1966年 | 85篇 |
1965年 | 96篇 |
1964年 | 100篇 |
1963年 | 44篇 |
1962年 | 91篇 |
1960年 | 104篇 |
1959年 | 35篇 |
1957年 | 41篇 |
1956年 | 37篇 |
1955年 | 40篇 |
1954年 | 67篇 |
1953年 | 38篇 |
1952年 | 49篇 |
1951年 | 38篇 |
1950年 | 61篇 |
1949年 | 44篇 |
1948年 | 33篇 |
排序方式: 共有5368条查询结果,搜索用时 359 毫秒
941.
Prof. Dr. Max Müller 《Pure and Applied Geophysics》1950,17(1-2):54-63
Zusammenfassung Es wird eine Induktionsimpulsmethode beschrieben, welche sich auf die Messung dielektrischer Dispersionsphänomene gründet, und welche einen direkten Nachweis des Petroleums auf Tiefen von über 2000 m ermöglicht. Durch Variation der Anfachungsbedingungen kann man selektive Reaktionswirkungen erzielen.
Summary An induction pulse method is described, based upon the measurement of a dielectric dispersion phenomenon. This method opens the possibility of a direct and selective reaction of the petroleum at a depth of more than 6000 feet. Hereby the selective reaction is based upon the variation of the exciting conditions.相似文献
942.
Dr. W. Buchheim 《Pure and Applied Geophysics》1950,16(1-2):81-86
Zusammenfassung Es wird untersucht, mit welcher Verzögerung und Verformung eine in einem Induktions-Seismometer erzeugte elektrische Spannungsschwankung die Registriervorrichtung erreicht, wenn die Uebertragung durch eine Leitung erfolgt. Es werden «Verformungszahlen» definiert, mittels deren sich Leitungen verschiedenen Typs hinsichtlich der Formtreue der Uebertragung vergleichen lassen. Einige Beispiele hierfür werden behandelt. Die erforderliche Selbstinduktivität (Pupinisierung) eine freischwebenden Doppelleitung für grösstmögliche Formtreue wird angegeben. Hierbei ergibt sich z.B. für 20 km Kabellänge eine Laufzeit von der Grössenordnung einer hundertstel Sekunde.
Summary It is beeing investigated, with which retarding and deforming one in an induction-seismometer generated electrical tension-oscillation the recorderapparatus arrives, presuming the transformation has been taken by means of wire. Numbers of deforming are given, which allowes the comparison by different types of wires, regarding the true shape of the transmission. A few examples will be described. The necessary selfinduction («Pupinisierung») of a freehanging doublewire for the greatest possible true shape is named. Thereby results for instance by a cablelength of 20 km a traveltime of about 1/100 of a second.相似文献
943.
Riassunto Viene discussa l'obiezione fondamentale fatta daSimpson contro l'ipotesi diKöhler sulla prevalenza dei nuclei salini di origine marina. Si richiama l'attenzione sul numero molto grande di nuclei che si formano nel gorgoglìo di aria in acqua di mare e si ricordano i numeri ottenuti sperimentalmente dagli AA. in altra epoca. L'efficacia del fenomeno di spruzamento in atto nelle burrasche viene pure illustrata.
Summary The fundamental objection, opposed bySimpson against the hypothesis ofKöhler concerning the prevalency of oceanic saline condensation nuclei is discussed. Attention is attracted upon experiments proving that the bubbling, also limited, in sea water produce great number of nuclei. The efficacy of water spraying is likewise discussed.相似文献
944.
Prof. Dr. G. Aliverti 《Pure and Applied Geophysics》1950,18(1):192-197
Riassunto Si dà conto delle osservazioni compiute, durante l'agosto 1950 sul plateau del ghiacciaio del Lys, circa la distribuzione e le caratteristiche dei coni di ghiaccio.
Summary Observations, made in August 1950, on the distribution and the characteristic features of ice-cones on Lys-glacier, are described.相似文献
945.
Prof. Dr. G. Boaga 《Pure and Applied Geophysics》1950,16(1-2):13-15
Riassunto Si determinano le precisioni con le quali possono venire osservate le deviazioni della verticale e si richiama l'attenzione su ciò quando si debbono interpretare le misure predette per prospezioni del sottosuolo.
Summary Measuring the deflections of the plumb-line the attainable precision is determined, in particular to investigations for geophysical prospecting.
Zusammenfassung Es wird für die Bestimmung der Lotabweichungen der erreichbare Genauigkeitsgrad untersucht, besonders im Hinblick auf Messungen zur Erforschung des Untergrundes.相似文献
946.
Dr. C. C. Wallén 《Pure and Applied Geophysics》1950,18(1):175-178
Summary A review is given of the investigations on variations in the general circulation in middle latitudes made byWillett andPetterssen. According toWillett a «high-index» type of circulation pattern with a strong zonal flow has probably caused the recent climatic improvement in the northern latitudes while the «low-index» type with meridional flow would create a cooling off in the same areas. According toPetterssen an other type of «low-index» pattern with a weak zonal flow and strong meridional exchange of air has been the essential cause of the warming up of the northern latitudes in Europe. This implies that the definition of the «low-index» type is not clear and gives rise to misunderstanding. Making use of our experience on glacier retreat in northern Scandinavia it is concluded that thePetterssen type of circulation more probably than the «high-index» type has caused the warming-up in the North Atlantic area from which the retreat of the glaciers has followed. 相似文献
947.
Prof. Dr. Luigi Castoldi 《Pure and Applied Geophysics》1950,18(1):160-161
Riassunto Si fa uso di una formula di derivazione di un integrale di superficie per dimostrare un teorema meteorologico diV. Bjerknes.
Summary Use is made of a differentiation's formula for surface integrals in showing aV. Bjerknes' meteorological theorem.相似文献
948.
Dr. R. A. Hirvonen 《Pure and Applied Geophysics》1950,18(1):103-106
Summary The recording of the contact times of a solar eclipse on two stations provides a geodetic measurement of the arc between the stations. The applications of this idea hitherto undertaken and the relevant apparature are briefly summarized. Some experiences obtained at the measuring of the records and at the computing of the results are described. 相似文献
949.
Dr. H. Arakawa 《Pure and Applied Geophysics》1951,20(1):56-61
Summary Many writers treated on the problem of dynamic instability of westerly flow due to the excessive horizontal shear, and the present author discusses the corresponding dynamic instability due to the vertical shear. The critical vertical shear in indifferent stratification is given by the condition — the meridional component of absolute vorticity vanishes, — and is an approximate negative valueof 10–4
sec
–1 in middle latitude. However the critical vertical shear in normal stable stratification is a fairly large negative value of 2 sec–1. It might be emphasized that the problem of this study differs fromRichardson's criterion of turbulence, for the present author discusses the condition under which the zonal flow is dynamically stable, whileRichardson expressed the condition under which the turbulence will decrease. 相似文献
950.
Prof. Dr. K. Schneider-Carius 《Pure and Applied Geophysics》1951,19(1-2):105-107
Ohne Zusammenfassung 相似文献