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951.
Ethnic Enclave Reconfiguration: A ‘new’ Chinatown in the Making 总被引:1,自引:0,他引:1
Years of past research on traditional Chinatowns were based on the assumption that Chinatown is an ethnic enclave for a single
ethnic minority, i.e. the Chinese. In recent years, one could observe significant changes over Chinatowns in terms of more
Vietnamese presence. Yet, the transition process as an object of study is much under-represented in the literature on ethnic
enclaves. Looking at ethnic business transition from Hong Kong to Vietnamese in Toronto’s Chinatown West, this paper argues
strongly that ‘multiple ethnicity’ can coexist in an enclave. For this case study, the Chinatown is being reconfigured into a ‘new’ Chinatown. Drawing upon data from the authors’ Vietnamese Business Database that covers information between
1983 and 2003, we present both spatial and temporal analyses that offer insights into how the Vietnamese businesses grow through
time. Our findings support the existence of a Vietnamization process in Toronto Chinatown West. However, its evolution is
still in an infant stage. In some aspects, the incoming Vietnamese businesses display similarities with the remaining Hong
Kong businesses. In sum, a total reconfiguration of Chinatown West in form and business nature is still unaccomplished. The
conventional enclave concept which bases on the singularity of ethnic group has to be abandoned in view of rising occurrence
of ethnic transition, particularly in this globalizing era. 相似文献
952.
Being the cause of the loss of life and damaging property, landslide is an important natural hazard. Therefore, landslides have to be monitored and preventive measures taken accordingly. In Geodesy, landslides can be determined with static, kinematic and dynamic geodetic models. The aim of this study is to develop a dynamic geodetic model for landslides and compare it with static and kinematic geodetic models. A study area was selected in the Northeastern Black Sea Region of Turkey where landslides are the most effective natural hazard. Movements were determined with static, kinematic and dynamic geodetic models using geodetic, geologic and geophysical measurements made in the study area. Groundwater levels changes were regarded as causative forces in the formulation of the dynamic model. The dynamic model delivered more detailed information (direction, values, velocity, acceleration of movements) about landslide movements. It is possible to formulate more realistic strategies about prevention of landslides by using this information. As a result, it can be suggested that dynamic geodetic models are more useful in landslide studies. 相似文献
953.
José?Badalmiguelvb@unizar.es" title="badal@unizar.es miguelvb@unizar.es" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author Miguel?Vázquez-prada álvaro?González 《Natural Hazards》2005,34(3):353-374
Prognostic estimations of the expected number of killed or injured people and about the approximate cost associated with the damages caused by earthquakes are made following a suitable methodology of wide-ranging application. For the preliminary assessment of human life losses due to the occurrence of a relatively strong earthquake we use a quantitative model consisting of a correlation between the number of casualties and the earthquake magnitude as a function of population density. The macroseismic intensity field is determined in accordance with an updated anelastic attenuation law, and the number of casualties within areas of different intensity is computed using an application developed in a geographic information system (GIS) environment, taking advantage of the possibilities of such a system for the treatment of space-distributed data. The casualty rate, defined as the number of killed people divided by the number of inhabitants of the affected region, is also computed and we show its variation for some urban concentrations with different population density. For a rough preliminary evaluation of the direct economic cost derived from the damages, equally through a GIS-based tool, we take into account the local social wealth as a function of the gross domestic product of the country. This last step is performed on the basis of the relationship of the macroseismic intensity to the earthquake economic loss in percentage of the wealth. Such an approach to the human casualty and damage levels is carried out for sites near important cities located in a seismically active zone of Spain, thus contributing to an easier taking of decisions in emergency preparedness planning, contemporary earthquake engineering and seismic risk prevention. 相似文献
954.
Release of CO2 from surface ocean water owing to precipitation of CaCO3 and the imbalance between biological production of organic matter and its respiration, and their net removal from surface
water to sedimentary storage was studied by means of a quotient θ = (CO2 flux to the atmosphere)/(CaCO3 precipitated). θ depends not only on water temperature and atmospheric CO2 concentration but also on the CaCO3 and organic carbon masses formed. In CO2 generation by CaCO3 precipitation, θ varies from a fraction of 0.44 to 0.79, increasing with decreasing temperature (25 to 5°C), increasing atmospheric
CO2 concentration (195–375 ppmv), and increasing CaCO3 precipitated mass (up to 45% of the initial DIC concentration in surface water). Primary production and net storage of organic
carbon counteracts the CO2 production by carbonate precipitation and it results in lower CO2 emissions from the surface layer. When atmospheric CO2 increases due to the ocean-to-atmosphere flux rather than remaining constant, the amount of CO2 transferred is a non-linear function of the surface layer thickness because of the back-pressure of the rising atmospheric
CO2. For a surface ocean layer approximated by a 50-m-thick euphotic zone that receives input of inorganic and organic carbon
from land, the calculated CO2 flux to the atmosphere is a function of the CaCO3 and Corg net storage rates. In general, the carbonate storage rate has been greater than that of organic carbon. The CO2 flux near the Last Glacial Maximum is 17 to 7×1012 mol/yr (0.2–0.08 Gt C/yr), reflecting the range of organic carbon storage rates in sediments, and for pre-industrial time
it is 38–42×1012 mol/yr (0.46–0.50 Gt C/yr). Within the imbalanced global carbon cycle, our estimates indicate that prior to anthropogenic
emissions of CO2 to the atmosphere the land organic reservoir was gaining carbon and the surface ocean was losing carbon, calcium, and total
alkalinity owing to the CaCO3 storage and consequent emission of CO2. These results are in agreement with the conclusions of a number of other investigators. As the CO2 uptake in mineral weathering is a major flux in the global carbon cycle, the CO2 weathering pathway that originates in the CO2 produced by remineralization of soil humus rather than by direct uptake from the atmosphere may reduce the relatively large
imbalances of the atmosphere and land organic reservoir at 102–104-year time scales. 相似文献
955.
随着油田开发难度的加大,开发中仅仅把储集砂体的沉积相类型确定下来是远远不够的,还要求准确地预测砂体的宽度、长度等定量参数,这就是本文所指的沉积相定量研究。本文根据大量钻井资料,在地层精细划分对比的基础上,对青海砂西油田E31辫状河三角洲平原和曲流河三角洲平原进行了定量研究,确定了分流河道砂体的宽度、宽/厚比等参数。研究表明,本区辫状河三角洲平原的分流河道砂体宽多为 1200-3000m,厚多为5-10m,宽/厚比200-280。曲流河三角洲平原的分流河道砂体宽多为 400-700m,厚多为3-6m,宽/厚比80-110。辫状分流河道砂体比曲流分流河道砂体普遍宽、厚是由于辫状分流河道频繁摆动改道引起砂体的横向拼合和垂向叠置所致。这种河道可称复合河道。利用“厚度中心法”可区分复合河道与单河道。由于不同沉积相的砂体宽度不同,在油田开发中井网部署方案应该不同。 相似文献
956.
957.
为了更好地研究神狐海域试采区天然气水合物的展布形态和赋存状况,基于高精度层析速度反演后的叠前深度偏移地震资料进行AVO反演技术研究。为在天然气水合物富集区有效地进行AVO研究,AVO处理前运用叠前深度偏移技术,通过高精度层析反演不断迭代速度模型;然后通过偏移来改善资料的质量,结合实测钻井资料进行AVO正演分析、反演可行性分析、属性交会分析;最后将具有高横向分辨能力的地震资料和高垂向分辨能力的测井资料与地质相结合进行叠前同时反演。该方法可反演出纵、横波阻抗等属性,直接进行岩性和流体识别,结果表明,在AVO反演中引入叠前深度偏移技术,为反演提供了较高质量的叠前共反射点道集和精细的层速度模型,改善了AVO技术在试采区的应用效果,提高了反演的可靠性。反演出的各种属性为AVO分析提供了丰富的信息,能够比较准确地反映地下水合物矿体的展布情况,可用于后续水合物储层的分析及综合研究,对未来的水合物勘探开采具有重要的现实意义。 相似文献
958.
959.
New microthermometric data combined with stable isotope geochemistry and paragenetic relationships support a previously suggested
cooling–mixing model for the iron oxide–copper–gold mineralization in the Mantoverde district. Fluid inclusions show characteristics
of a CO2-bearing aqueous NaCl ± CaCl2 salt system. The evolution of the Mantoverde hydrothermal system is characterized by (1) an early hypersaline, high to moderate
temperature fluid; (2) a moderate saline, moderate temperature fluid; and (3) a low saline, moderate to low temperature fluid.
Early magnetite formation took place at median temperatures of 435.0°C, whereas hematite formed at median temperatures of
334.4°C. The main sulfide mineralization texturally post-dates the iron oxides and occurred before late-stage calcite, which
developed at a median temperature of 244.8°C. Boiling occurs only locally and is of no relevance for the ore formation. The
microthermometric and stable isotope data are supportive for a fluid cooling and mixing model, and suggestive for a predominantly
magmatic–hydrothermal fluid component during the iron oxide and main sulfide mineralization. Thereafter, the incursion of
a nonmagmatic fluid of ultimately meteoric or seawater gains more importance. 相似文献
960.
Lidong?Dai Heping?LiEmail author Haiying?Hu Shuangming?Shan Jianjun?Jiang Keshi?Hui 《Contributions to Mineralogy and Petrology》2012,163(4):689-700
The in situ electrical conductivity of hydrous garnet samples (Py20Alm76Grs4–Py73Alm14Grs13) was determined at pressures of 1.0–4.0 GPa and temperatures of 873–1273 K in the YJ-3000t apparatus using a Solartron-1260
impedance/gain-phase analyzer for various chemical compositions and oxygen fugacities. The oxygen fugacity was controlled
by five solid-state oxygen buffers (Fe2O3 + Fe3O4, Ni + NiO, Fe + Fe3O4, Fe + FeO, and Mo + MoO2). Experimental results indicate that within a frequency range from 10−2 to 106 Hz, electrical conductivity is strongly dependent on signal frequency. Electrical conductivity shows an Arrhenius increase
with temperature. At 2.0 GPa, the electrical conductivity of anhydrous garnet single crystals with various chemical compositions
(Py20Alm76Grs4, Py30Alm67Grs3, Py56Alm43Grs1, and Py73Alm14Grs13) decreases with increasing pyrope component (Py). With increasing oxygen fugacity, the electrical conductivity of dry Py73Alm14Grs13 garnet single crystal shows an increase, whereas that of a hydrous sample with 465 ppm water shows a decrease, both following
a power law (exponents of 0.061 and −0.071, respectively). With increasing pressure, the electrical conductivity of this hydrous
garnet increases, along with the pre-exponential factors, and the activation energy and activation volume of hydrous samples
are 0.7731 ± 0.0041 eV and −1.4 ± 0.15 cm3/mol, respectively. The results show that small hopping polarons
( \textFe\textMg · ) \left( {{\text{Fe}}_{\text{Mg}}^{ \cdot } } \right) and protons (
\textH · {\text{H}}^{ \cdot } ) are the dominant conduction mechanisms for dry and wet garnet single crystals, respectively. Based on these results and
the effective medium theory, we established the electrical conductivity of an eclogite model with different mineral contents
at high temperatures and high pressures, thereby providing constraints on the inversion of field magnetotelluric sounding
results in future studies. 相似文献