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51.
52.
The tremendous changes in China's development philosophy and regional economies during the last two decades have carved out selectively new locations of development across the nation. While politicians heatedly debate the acceptable levels of regional inequality, most scholarly studies focus on broad aggregate trends of inequality among provinces and groups of provinces, and pay little attention to identifying and conceptualizing sources and major agents of spatial change. This paper aims at revealing detailed spatial ramifications of the reforms, and at understanding the impacts of the state, local agents, and foreign investors on regional development. To this effect, we conduct a disaggregated and empirical study of Jiangsu, a coastal province experiencing dramatic economic and spatial restructuring. We show that local agents which favor rural industrial enterprises accelerated new growth in selected rural areas, in contrast to slower growth of older cities and state‐owned enterprises, resulting in a net decline of intercounty inequality. But the coalescence of state policy, local agents, and foreign investment has widened the historical gap between northern and southern Jiangsu, and is likely to accelerate intercounty inequality in the future. Our study demonstrates the utility of the “developments from above, below and outside” framework for analyzing key forces of regional growth in socialist transitional economies. 相似文献
53.
农村剩余劳动力外了是我国人多地少、以农业为主要经济部门地区的普遍现象。在经济发展水平较高地区,又有欠发达区农村劳动力的补偿性流入及妇女的婚姻迁入。文中以对劳动力外出和妇女的婚姻迁入都极为活跃的高州市的实际调查为例,分析自然资源条件和经济结构对人口迁移的影响。 相似文献
54.
55.
Allison Schein Simon C. Courtenay Cindy S. Crane Kevin L. Teather Michael R. van den Heuvel 《Estuaries and Coasts》2012,35(3):799-810
Artificial fertilizers are contributing to the replacement of eelgrass (Zostera marina) by sea lettuce (Ulva lactuca) in estuaries of Prince Edward Island (PEI), Canada. In this study, we found that the nearshore fish community differed between
areas dominated by these two vegetations within an estuary in every month sampled (April–August). Adult northern pipefish
(Syngnathus fuscus), threespine stickleback (Gasterosteus aculeatus), blackspotted stickleback (Gasterosteus wheatlandi), and Atlantic silverside (Menidia menidia) were most strongly associated with eelgrass, while mummichog (Fundulus heteroclitus), ninespine stickleback (Pungitius pungitius), and American eel (Anguilla rostrata) were often more numerous in sea lettuce. Sea lettuce stations tended to have more young-of-the-year mummichog, fourspine
stickleback (Apeltes quadracus), and Gasterosteus sp. than eelgrass stations but fewer young-of-the-year northern pipefish and Atlantic silverside. Fish richness and abundance
were significantly lower in the sea lettuce than eelgrass habitat during August when benthic hypoxia occurred. We conclude
that the loss of eelgrass from PEI estuaries will result in significant declines in fish biodiversity. 相似文献
56.
The Corsica River, located on Maryland’s eastern shore, has been the site of restoration efforts targeting sediment and nutrient
load reductions. Previous work has indicated that agricultural activities supply most of these materials; however, their dynamics
and fate are largely unknown. To address these needs, bottom sediments have been collected and analyzed for their chemical
and textural properties. Long-term (decadal) accumulation rates are determined with 210Pb (half-life 22.3 years), verified with 137Cs, and range from 0.18 to 0.84 g/cm2/year in the subtidal region and 0.3–1.89 g/cm2/year in the marshes. These estimates are compared with likely sediment sources to determine the direction of exchange with
the adjacent estuary (Chester River), which is a subtributary of Chesapeake Bay, with the Chester River likely supplying 0.94 × 103 t/year of sediment to the Corsica, ∼16% of the total sediment input. The radiochemical data are used to interpret profiles
of grain size and nitrogen and to provide improved estimates of nitrogen burial. Comparison of the Corsica River to similar
systems highlights the importance of marshes in trapping sediment and nutrient inputs from the watershed. 相似文献
57.
A unique feature of migration in China is its two-track system, one consisting of permanent migration and temporary migration. This article examines whether and how hukou reforms and the maturation of migration streams since the 1980s have changed the two-track system. Using data on interprovincial migration from the 1990 and 2000 censuses, our empirical analysis focuses on the differentials between permanent migrants and temporary migrants and their changes over time. We document the size, migration reasons, and selectivity of migrants, and we evaluate the determinants of the dichotomy between permanent migrants and temporary migrants via logistic regression models. Our findings show that between 1990 and 2000 the gaps between interprovincial permanent migrants and temporary migrants did not narrow but in most aspects had widened. There is little evidence that hukou reforms have lowered the barriers to urban citizenship. At the same time, a larger spectrum of the rural population has joined the temporary migration streams. The net result is a persistence of the two-track migration system, where permanent migrants increasingly assume the position of social and economic elites and temporary migrants are the disadvantaged and disenfranchised. 相似文献
58.
Jianhong Xue Cindy LeeStuart G. Wakeham Robert A. Armstrong 《Organic Geochemistry》2011,42(4):356-367
Principal components analysis (PCA) is a multivariate data analysis tool that can be used to recombine the variables of a large multivariate dataset in such a way that the first few variables of the reconstructed dataset account for the majority of the variance in the data. Application of PCA in marine geochemistry has become quite common in recent years. In this study, we illustrate the use of PCA through examples that arose while investigating the geochemistry of sinking particles during the MedFlux project. The examples presented do not simply repeat the analyses of the original study, but instead extend them in the context of simultaneous application of PCA and cluster analysis. Our results show that constructing a one dimensional (1D) “degradation index” using only the first principal component (PC) is in most cases oversimplified, and that constructing 2D or 3D “degradation trajectories” with the first 2 or 3 PCs is more informative. Use of the first three PCs is indicated when the variance explained by the third PC is comparable in magnitude to that explained by the second PC in the reconstructed dataset. We also discuss the use of scree plots and cluster analysis in helping decide whether the third PC is needed to capture the essential information in the dataset. 相似文献
59.
Pallav Ray Chidong Zhang Mitchell W. Moncrieff Jim Dudhia Julie M. Caron L. Ruby Leung Cindy Bruyere 《Climate Dynamics》2011,36(1-2):161-184
Tropical channel models, defined as models that are global in the zonal direction but bounded in the meridional direction, are particularly useful for simulating the Madden-Julian oscillation (MJO) and understanding its physical and dynamical basis. Influences from the extratropics through the lateral boundaries have been found to be essential to the reproduction of the initiation of certain MJO events. This led to a hypothesis that multi-year simulations using a tropical channel model would reproduce reasonable MJO statistics under the influence of prescribed lateral boundary conditions derived from global reanalyses. Interestingly, the MJO statistics in such a multi-year simulation by a high-resolution tropical channel model are not better than those from global climate models. The error in the atmospheric mean state is found to be a possible reason for the poor MJO statistics in the simulation. Nevertheless, even with a large error in the mean state, the multi-year simulation captures two MJO events previously found to be initiated by extratropical influences. However, the model does not reproduce a third event, whose initiation is not directly influenced by the extratropics. This implies that in the absence of dynamical interactions between the MJO and the lateral boundary conditions, the error in the mean state could be sufficient to prevent the MJO initiation. To explore this third MJO event further, a series of sensitivity tests are conducted. These tests show that the simulation of this event is neither critically influenced by the cumulus parameterization employed, nor the initial conditions when the model is integrated 2?weeks prior to the MJO initiation. The model captures this event when the MJO signal is already present in the initial conditions. The use of high-resolution sea surface temperature does not improve the simulation of the third MJO event. A higher-resolution nested domain covering the Indo-Pacific warm pool region and including a cloud-system resolving domain over the Indonesian Maritime Continent has little effect on the MJO initiation over the Indian Ocean. In <2?weeks the error in the simulation is comparable to the climate error. The role of the simulated MJO on the mean state is also explored. Implications and limitations of these results are discussed. 相似文献
60.
Bias corrections of global models for regional climate simulations of high-impact weather 总被引:1,自引:1,他引:0
Cindy L. Bruyère James M. Done Greg J. Holland Sherrie Fredrick 《Climate Dynamics》2014,43(7-8):1847-1856
All global circulation models (GCMs) suffer from some form of bias, which when used as boundary conditions for regional climate models may impact the simulations, perhaps severely. Here we present a bias correction method that corrects the mean error in the GCM, but retains the six-hourly weather, longer-period climate-variability and climate change from the GCM. We utilize six different bias correction experiments; each correcting different bias components. The impact of the full bias correction and the individual components are examined in relation to tropical cyclones, precipitation and temperature. We show that correcting of all boundary data provides the greatest improvement. 相似文献