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111.
Klaus P. Hoinka 《Boundary-Layer Meteorology》1991,57(3):289-294
The note deals with looming during foehn north of the Alps. The results show that there is a weak effect in stretching optically the orography. However, the increase in view angle is probably not detectable by human observers looking south from Munich towards the Alps. The impression that the orography seems to be stretched during a foehn is also due to psychological effects which might be a factor of greater importance. 相似文献
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113.
Carbon dioxide (CO2) sequestration has been proposed as a key component in technological portfolios for managing anthropogenic climate change, since it may provide a faster and cheaper route to significant reductions in atmospheric CO2 concentrations than abating CO2 production. However, CO2 sequestration is not a perfect substitute for CO2 abatement because CO2 may leak back into the atmosphere (thus imposing future climate change impacts) and because CO2 sequestration requires energy (thus producing more CO2 and depleting fossil fuel resources earlier). Here we use analytical and numerical models to assess the economic efficiency of CO2 sequestration and analyze the optimal timing and extent of CO2 sequestration. The economic efficiency factor of CO2 sequestration can be expressed as the ratio of the marginal net benefits of sequestering CO2 and avoiding CO2 emissions. We derive an analytical solution for this efficiency factor for a simplified case in which we account for CO2 leakage, discounting, the additional fossil fuel requirement of CO2 sequestration, and the growth rate of carbon taxes. In this analytical model, the economic efficiency of CO2 sequestration decreases as the CO2 tax growth rate, leakage rates and energy requirements for CO2 sequestration increase. Increasing discount rates increases the economic efficiency factor. In this simple model, short-term sequestration methods, such as afforestation, can even have negative economic efficiencies. We use a more realistic integrated-assessment model to additionally account for potentially important effects such as learning-by-doing and socio-economic inertia on optimal strategies. We measure the economic efficiency of CO2 sequestration by the ratio of the marginal costs of CO2 sequestration and CO2 abatement along optimal trajectories. We show that the positive impacts of investments in CO2 sequestration through the reduction of future marginal CO2 sequestration costs and the alleviation of future inertia constraints can initially exceed the marginal sequestration costs. As a result, the economic efficiencies of CO2 sequestration can exceed 100% and an optimal strategy will subsidize CO2 sequestration that is initially more expensive than CO2 abatement. The potential economic value of a feasible and acceptable CO2 sequestration technology is equivalent – in the adopted utilitarian model – to a one-time investment of several percent of present gross world product. It is optimal in the chosen economic framework to sequester substantial CO2 quantities into reservoirs with small or zero leakage, given published estimates of marginal costs and climate change impacts. The optimal CO2 trajectories in the case of sequestration from air can approach the pre-industrial level, constituting geoengineering. Our analysis is silent on important questions (e.g., the effects of model and parametric uncertainty, the potential learning about these uncertainties, or ethical dimension of such geoengineering strategies), which need to be addressed before our findings can be translated into policy-relevant recommendations. 相似文献
114.
Carbon Sequestration in Arable Soils is Likely to Increase Nitrous Oxide Emissions,Offsetting Reductions in Climate Radiative Forcing 总被引:5,自引:0,他引:5
Strategies for mitigating the increasing concentration of carbon dioxide (CO2) in the atmosphere include sequestering carbon (C) in soils and vegetation of terrestrial ecosystems. Carbon and nitrogen
(N) move through terrestrial ecosystems in coupled biogeochemical cycles, and increasing C stocks in soils and vegetation
will have an impact on the N cycle. We conducted simulations with a biogeochemical model to evaluate the impact of different
cropland management strategies on the coupled cycles of C and N, with special emphasis on C-sequestration and emission of
the greenhouse gases methane (CH4) and nitrous oxide (N2O). Reduced tillage, enhanced crop residue incorporation, and farmyard manure application each increased soil C-sequestration,
increased N2O emissions, and had little effect on CH4 uptake. Over 20 years, increases in N2O emissions, which were converted into CO2-equivalent emissions with 100-year global warming potential multipliers, offset 75–310% of the carbon sequestered, depending
on the scenario. Quantification of these types of biogeochemical interactions must be incorporated into assessment frameworks
and trading mechanisms to accurately evaluate the value of agricultural systems in strategies for climate protection. 相似文献
115.
华东稻麦轮作农田CH4、N2O和NO排放特征 总被引:2,自引:0,他引:2
利用同步自动观测系统对华东稻麦轮作农田的CH4、N2O和NO排放进行了长期连续观测,分析了这3种气体排放的季节特征及决定因素,结果表明,华东稻麦轮作农田的CH4、N2O和NO排放具有完全不同的季节变化形式。CH4的排放发生在水稻生长期,其他阶段排放不明显,土壤水分状况是决定整个轮作周期内CH4排放变化的主要因素。N2O排放具有"冬季无,水田少,旱地多"的季节变化特点,尤其以旱地阶段的排放为主,土壤水分状况和温度共同决定着N2O排放的季节变化形式。NO排放具有"冬季无,水田很少,春季旱地多于秋季旱地"的季节分布特点,轮作周期内97.3%±0.6%的NO排放都发生在除冬季以外的旱地阶段,NO排放的季节变化形式由土壤水分状况和温度共同决定。大多数情况下稻田CH4和N2O排放呈互为消长的关系,但在烤田期间,二者却有时甚至同时出现高排放。在N2O日平均排放通量小于5 mg.m-2.h-1时,稻麦轮作农田的N2O和NO排放呈明显的互为消长关系,但大于5 mg.m-2.h-1时,N2O排放很强,同时NO排放也很强。 相似文献
116.
In order to meet the challenge of climate change while allowing for continued economic development, the world will have to
adopt a net zero carbon energy infrastructure. Due to the world’s large stock of low-cost fossil fuels, there is strong motivation
to explore the opportunities for capturing the CO2 that is produced in the combustion of fossil fuels and keeping it out of the atmosphere. Three distinct sets of technologies
are needed to allow for climate neutral use of fossil fuels: (1) capture of CO2 at concentrated sources like electric power plants, future hydrogen production plants and steel and cement plants; (2) capture
of CO2 from the air; and (3) the safe and permanent storage of CO2 away from the atmosphere. A strong regime of carbon accounting is also necessary to gain the public’s trust in the safety
and permanence of CO2 storage. This paper begins with an extensive overview of carbon capture and storage technologies, and then presents a vision
for the potential implementation of carbon capture and storage, drawing upon new ideas such as air capture technology, leakage
insurance, and monitoring using a radioactive isotope such as C-14. These innovations, which may provide a partial solution
for managing the risks associated with long-term carbon storage, are not well developed in the existing literature and deserve
greater study. 相似文献
117.
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119.
Regional climate modelling over complex terrain: an evaluation study of COSMO-CLM hindcast model runs for the Greater Alpine Region 总被引:1,自引:0,他引:1
In this study the results of the regional climate model COSMO-CLM (CCLM) covering the Greater Alpine Region (GAR, 4°–19°W and 43°–49°N) were evaluated against observational data. The simulation was carried out as a hindcast run driven by ERA-40 reanalysis data for the period 1961–2000. The spatial resolution of the model data presented is approx. 10 km per grid point. For the evaluation purposes a variety of observational datasets were used: CRU TS 2.1, E-OBS, GPCC4 and HISTALP. Simple statistics such as mean biases, correlations, trends and annual cycles of temperature and precipitation for different sub-regions were applied to verify the model performance. Furthermore, the altitude dependence of these statistical measures has been taken into account. Compared to the CRU and E-OBS datasets CCLM shows an annual mean cold bias of ?0.6 and ?0.7 °C, respectively. Seasonal precipitation sums are generally overestimated by +8 to +23 % depending on the observational dataset with large variations in space and season. Bias and correlation show a dependency on altitude especially in the winter and summer seasons. Temperature trends in CCLM contradict the signals from observations, showing negative trends in summer and autumn which are in contrast to CRU and E-OBS. 相似文献
120.
Daily maximum rainfall (R1D) was higher in the Jialing River basin, the Taihu Lake area and the mid-lower main stream section of the Yangtze River basin in the 1990s, and there was a good relationship between ECHAM5/MPI-OM model simulation and the observed data about extreme precipitation (R1D). Under the IPCC SRES A2, A1B, and B1 scenarios, R1Ds are all projected to be in increasing trends in the upper Yangtze River basin during 2001-2050, and R1D shows a more significant increasing tendency under the A2 scenario when compared with the A1B scenario before 2020. With respect to the middle and lower Yangtze River basin, an increasing tendency is projected before 2025, and since then the increasing tendency will become insignificant. There might be more floods to the south of the Yangtze River and more droughts to the north in the next decades. 相似文献