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131.
准噶尔盆地头屯河地区侏罗系陆相层序包含4种沉积:(1)冲积扇平原湿地中的砾石质河流沉积(八遭湾组),其特征提示在湿地中发育了规模不同的大河道(深3—5m,宽1OOm左右)及较小的分流或决口河道(深2m以下,宽6—30m)。(2)沙质低弯度河沉积,晚三工河、早西山窑、头屯河及齐古组沉积期的河流沉积属之。其特点是河道相与河间相间的界线清楚,提示河道在某一段时期固定于平原的特定地带;河道规模受古气候和构造的制约;气候干旱化和构造抬升(如头屯河组沉积时期),侵蚀基面降低,河流动力增加,因而河流规模变大,反之变小;晚头屯河组沉积期的干旱气候存在暂时性河道。(3)三角洲前缘沉积(河口中坝),见于八道湾、三工河及喀拉扎组中。(4)开阔湖相沉积,以三工河组厚的页岩层序为代表。 砂岩成分逆向反映源区剥蚀顺序。下侏罗统富含泥质岩屑,表示天山上古生界浅变质及沉积层系被剥蚀。自下而上,碎屑中稳定矿物增加,粒度变细,反映源区由于剥蚀而后退。中—上侏罗统砂岩成分演化方向不同于下侏罗统,可能与三工河组沉积末期盆地边缘构造回春有关。在Q-F-L三角图中,侏罗系样品大都落在构造区之间,反映陆相盆地充填物的混合来源。下—中侏罗统的煤既有原地生成,亦有重要的他生类型。  相似文献   
132.
A 29Si and 27Al magic angle spinning nuclear magnetic resonance study is reported for differently synthesized mullites. The 29Si MAS NMR spectra of all samples are essentially identical. They consist of a main resonance at -86.8 ppm, a shoulder around -90 ppm and a second resonance at -94.2 ppm. The main resonance is interpreted as being due to a sillimanite-type geometry around Si and the second one is tentatively assigned to a Si environment typical for mullite. The 27Al MAS NMR spectra of sinter- and fused-mullite measured at different Larmor frequencies revealed clearly the presence of three distinct Al sites in mullite, i.e. of octahedral (M1), tetrahedral (M2) and distorted tetrahedral (Al*) sites.  相似文献   
133.
Vegetation cover is the main factor of soil loss prevention. The C-factor of the RUSLE (Revised Universal Soil Loss Equation) was predicted with NDVI, ground data and exponential regression equation for mountain rangelands of Kyrgyzstan. Time series of C-factor, precipitation and temperature were decomposed into seasonal and trend components with STL (seasonal decomposition by loess) to assess their interrelations. C-factor, precipitation and temperature trend components indicated significant lagged correlation, whereas seasonal components indicated more complex relations with climate factors which can be promoting as well as limiting factors for vegetation development, depending on the season. Rainy springs and hot summers may increase soil loss dramatically, whereas warm and dry springs with rainy summers can decrease it. Steep slopes indicated higher soil loss ratio, whereas flat areas were better protected by vegetation.  相似文献   
134.
Zusammenfassung Es werden einige Tatsachen und Bedingungen angeführt, welche eine physikalische Deutung der erdmagnetischen Mikropulsationen zu berücksichtigen hätte. Um ein weltweites Erfassen der Mikropulsationen und ihrer Variationen zu erleichtern, wird ein Klassifizierungsverfahren vorgeschlagen, mit dem Größe, Regelmäßigkeit, Andauer oder Abwesenheit von Wellenzügen halbquantitativ erfaßt und statistisch behandelt werden können. Nach diesem Verfahren werden augenblicklich die Registrierungen der Horizontalkomponente im argentinischen Observatorium Orcadas durchmustert. Als Beispiel zeigt Abb. 2 den Tagesgang des Auftretens von Mikropulsationen verschiedener Regelmäßigkeit im Januar 1933. Es besteht ein charakteristischer Unterschied gegenüber den bisher bekannten Gängen an anderen Observatorien. Weitere Beispiele beleuchten den Zusammenhang mit erdmagnetischer Aktivität und mit Bai-Störungen; es besteht Anlaß, eine inhibierende Wirkung der ionisierenden Wellenstrahlung der Sonne anzunehmen (Abb. 3).
Summary Some facts and conditions are stated which are to be taken into account in any physical theory of geomagnetic micropulsations. For convenience in a world-wide survey of the micropulsations and their variations, a scheme of classification is suggested in which the magnitude, regularity, duration or absence of wave-trains are gauged in a semi-quantitative manner, as a first step for statistical discussion. The records of magnetic horizontal component from the Argentine South-Orkneys Observatory are now being searched for micropulsations in accordance with the procedure here suggested. As an illustration, Fig. 2 shows the daily variation of occurrence for micropulsations of different degrees of regularity during January, 1933. A significant difference is found between this daily variation and those known hitherto from other observatories. Further examples refer to relations with geomagnetic activity and bay-disturbances; there is some evidence of an inhibitory effect of ionizing solar wave-radiation (Fig. 3).

Resumen Se enumeran algunos hechos y condiciones que habrá de tomar en cuenta cualquier interpretación física de las micropulsaciones geomagnéticas. Con el fin de posibilitar un censo global de este fenómeno y sus variaciones, se sugiere un prodedimiento para su clasificación, el cual permite hacer un relevamiento semi-cuantitativo de la magnitud, regularidad, permanencia o ausencia de los trenes de ondas, y tratarlas estadísticamento. Según este método, se está procediendo en la actualidad a escrutar los registros de la componente horizontal, recogidos en el observatorio argentino de las Islas Orcadas. Como ejemplo, la Fig. 2 muestra la marcha diaria de la ocurrencia de micropulsaciones con diferentes grados de regularidad, en enero de 1933. Existe una discrepancia característica con las marchas que hasta aqui se conocen de otros observatorios. Algunos ejemplos adicionales ilustran las relaciones con el grado de actividad geomagnética y con los disturbios del tipo bahía; cabe tambien suponer un efecto impeditivo de la radiación solar ionizante (Fig. 3).

Résumé On énumère quelques faits et conditions dont devrait tenir compte une interprétation physique des micropulsations géomagnétiques. Dans le but de faciliter l'étude mondiale des micropulsations et de leurs variations, on propose un mode de classement embrassant la grandeur, la régularité, la durée ou l'absence de trains d'ondes sous forme semi-quantitative et qui permet leur étude statistique. C'est à l'aide de ce procédé que l'on a dépouillé actuellement les enregistrements de la composante horizontale à l'Observatoire argentin des Orcades du Sud. La fig. 2 est un exemple de la variation diurne de l'apparition de micropulsations plus ou moins régulières en janvier 1933; cette variation diffère d'une façon caractéristique de celles que l'on connaît jusqu'ici en d'autres observatoires. D'autres exemples illustrent la relation avec l'activité géomagnétique et avec les perturbations du type baie; il y a lieu d'admettre un effet inhibitif du rayonnement ondulatoire solaire ionisant (fig. 3).


Mit 3 Textabbildungen.

Veröffentlicht mit Erlaubnis der Dirección General del Servicio Meteorológico Nacional, Buenos Aires.  相似文献   
135.
136.
During a cruise on board RV Gauss in May/June 1988, joint investigations into organochlorine compounds, dissolved trace metals, petroleum hydrocarbons and basic hydrography were carried out at representative stations of the Baltic Monitoring Programme (BMP). The aim of the cruise was to study distribution patterns and — using previous data — to establish temporal trends if at all discernible.Each group of contaminants investigated showed specific characteristics, with differences even between compounds within the same group. The differences are due to:
–  - the partition of contaminants between dissolved and adsorbed form;
–  - the response to redox conditions;
–  - the influence of microbial decay, organic production or changes in speciation.
  相似文献   
137.
The `plate tectonic mirror image' to the region of the Cocos and Nazca plates, which are currently being subducted beneath Central America, is preserved in the Central Pacific around 120°W just south of the equator. Cruise SO‐180 investigated this remote area during project CENTRAL and acquired new magnetic and bathymetric data. A plate tectonic model for the ‘mirror image’ is presented based on the newly acquired as well as reprocessed existing data. Discordant magnetic anomaly patterns and bathymetric structures indicate at least two major reorganization events (19.5 and 14.7 Myr), which can be detected both in the Cocos‐Nazca spreading system and in the East Pacific Rise. Irregularities in the anomaly pattern and curvilinear structures on the sea floor of the survey area are interpreted in terms of a fossil overlapping spreading centre at the location where the Farallon break‐up originated.  相似文献   
138.
No-till (NT) is a conservation system that improves the hydrological regime of agricultural slopes by providing greater surface protection and benefits to the physical and hydrological properties of soils. However, the isolated use of NT is not enough to control runoff and its associated degradation processes. Therefore, this study aimed to evaluate the runoff of agricultural slopes under NT under different runoff control conditions by monitoring 63 rainfall events in two 2.4-ha zero-order catchments and 27 rainfall events in four 0.6-ha macroplots. The catchments are paired and similar in terms of the type of soil and relief, but different regarding the presence of terraces. The macroplots have different soil and crop management systems. By using monitoring techniques, the hyetographs and hydrographs revealed the influence of the different types of management on the catchments and macroplots and allowed rainfall characteristics, runoff volume, runoff coefficients, water infiltration, peak runoff, response times, and curve number to be analysed. The terraces positively affected the NT and controlled runoff and related variables, in addition to infiltration significantly increasing and runoff reducing in the terraced catchment. All the hydrological information assessed pointed to the positive effects provided by the presence of the terraces. The results in the macroplots showed that high amounts of phytomass and/or chiselling do not control runoff and its correlated variables in medium and high magnitude events. The study concludes by underlining the need for additional measures to control runoff (terraces), even in areas under NT and with high phytomass production. Additionally, the study emphasizes the importance of monitoring at the catchment scale to better understand the hydrological behaviour of agricultural areas and provide the necessary parameters to effectively control runoff.  相似文献   
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140.
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