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991.
海岸带综合管理的若干问题 总被引:14,自引:0,他引:14
根据海岸带综合管理实践经验,阐述和讨论了当前海岸带综合管理存在的地位、法律、科学、人才等主要问题,并提出了强化综合管理意识、构筑法律框架、统一定义与标难和加强培训等策略,为加快实施海岸带综合管理提供参考和建议。 相似文献
992.
The molluscan macrofauna living in shallow muddy bottoms with the green algae Caulerpa prolifera was studied monthly between February 1994 and January 1996 in the inner Bay of Cádiz (SW Spain). The molluscan assemblage followed a similar pattern over the 2 years, displaying seasonal trends in species richness, abundance and structure. During the autumn and winter months, a decrease in abundance, species richness and diversity and an increase in evenness occurred. During the spring and summer months, the molluscan assemblage was characterised by an increase in species richness, abundance and diversity. These seasonal trends were supported statistically by the presence of significantly different groupings of seasonal samples in multivariate analyses.Despite human impacts in the bay (e.g. aquaculture activities, sewage), the presence of repetitive seasonal trends, based on the qualitative and quantitative data, indicates the stability of the molluscan assemblage over 2 years. Benthic characteristics from the inner Bay of Cádiz, such as shallow soft bottoms with the presence of macrophytes and current dynamics, seem to be key factors influencing the composition and seasonality of this molluscan assemblage. 相似文献
993.
Larval fish assemblages in nearshore coastal waters off central Chile: temporal and spatial patterns 总被引:1,自引:0,他引:1
E. Hernndez-Miranda A. T. Palma F. P. Ojeda 《Estuarine, Coastal and Shelf Science》2003,56(5-6):1075-1092
In this study we identified spatial and temporal patterns in the distribution and abundance of larval stages of several fish species in nearshore waters off central Chile. Larvae were sampled monthly at two close (20 km apart) but contrasting localities, El Quisco and Las Cruces. Surveys corresponded to standard plankton tows stratified according to bathymetry and distance from shore. Our results indicate that at both localities: (1) there is a seasonal reproductive pattern for most of the species studied; (2) there is a seasonal-related change in larval species composition and abundance, with austral Winter–Spring being the time of greatest diversity; (3) larval stages of several species that, as adults occupy intertidal, estuarine–riverine, subtidal, benthic-demersal, epipelagic or mesopelagic habitats, are found within these coastal environments; (4) there is a distinctive cross-shelf pattern of larval distribution, which seems to correspond, at least for the intertidal species, with the shallower (<30 m depth) portion of area surveyed; and (5) there is a coupling between the patterns of distribution and abundance of the entire ichthyoplankton assemblage with short-term physical features such as wind forcing, Ekman transport, and local currents. Our findings suggest that both the specific composition as well as the abundance of larval fish species varies spatially and temporally and that this variability may result from the interaction of physical and biological factors at different scales. 相似文献
994.
Bruno Lansard Christophe Rabouille Lionel Denis Christian Grenz 《Estuarine, Coastal and Shelf Science》2009,81(4):544-554
Biogeochemical processes in sediments under the influence of the Rhône River plume were studied using both in situ microelectrodes and ex situ sediment core incubations. Organic carbon (OC) and total nitrogen (TN) content as well as stable carbon isotopic composition of OC (δ13COC) were analysed in 19 surface sediments to determine the distribution and sources of organic matter in the Rhône delta system. Large spatial variations were observed in both the total O2 uptake (5.2 to 29.3 mmol m−2 d−1) and NH4+ release (−0.1 to −3.5 mmol m−2 d−1) rates at the sediment–water interface. The highest fluxes were measured near the Rhône River mouth where sedimentary OC and TN contents reached 1.81% and 0.23% respectively. Values of δ13COC ranged from −26.83‰ to −23.88‰ with a significant seawards enrichment tracing the dispersal of terrestrial organic matter on the continental shelf. The amount of terrestrial-derived OC reaches 85% in sediments close to the Rhône mouth decreasing down to 25% in continental shelf sediments. On the prodelta, high terrestrial OC accumulation rates support high oxygen uptake rates and thus indicating that a significant fraction of terrestrial OC is remineralized. A particulate organic carbon (POC) mass balance indicates that only 3% of the deposited POC is remineralized in prodelta sediments while 96% is recycled on the continental shelf. It was calculated that a large proportion of the Rhône POC input is either buried (52%) or remineralized (8%), mostly on the prodelta area. The remaining fraction (40%) is either mineralized in the water or exported outside the Rhône delta system in dissolved or particulate forms. 相似文献
995.
Richard D. Brodeur Joseph P. Fisher Yasuhiro Ueno Kazuya Nagasawa William G. Pearcy 《Journal of Oceanography》2003,59(4):415-434
During the 1980s and 1990s, scientific research cruises were conducted in both the eastern and western boundary regions of
the North Pacific Ocean. The main purpose of these cruises was to examine the abundance and distribution patterns of juvenile
salmon in coastal waters. These studies created one of the most extensive databases ever collected on the species composition
of coastal Transition Zone epipelagic nekton in the North Pacific Ocean. Catch data from two purse seine and two surface trawl
surveys (one each from off northern Japan and eastern Russia and off the West Coast of the U.S.) were examined using multivariate
techniques to analyze the community structure of nektonic cephalopods, elasmobranchs, and teleosts in the coastal zone during
the summer and autumn months. Juvenile salmonids are generally among the most common species caught, but in terms of overall
abundance, other potential competitors with juvenile salmon, such as small squids and clupeoid fishes predominated the catches.
Species diversity and dominance varied among areas and gear types. Distinct assemblages were found in each area, but the two
regions had closely related species occupying similar ecological positions in each habitat.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
997.
针对鲁西南平原地区采煤塌陷地特点及其主要危害,总结了采煤塌陷灾害的防、减措施和本区4种成功的塌陷地治理模式,并远景性地提出了运用黄河落淤法治理塌陷地和建设湿地改造塌陷地的综合治理系统工程。 相似文献
998.
复合载体夯扩桩是由干硬性混凝土及填充料等经细长锤夯扩形成的复合载体和钢筋混凝土桩身组成。它具有挤密地基及扩大桩端面积的双重作用。此技术以环境污染小(无泥浆)、节约资源且较经济(桩径小),而得到较快的发展和应用。本文结合工程实际,对其在河漫滩地区的应用进行探讨,为今后在同类地区的设计和施工提供参考。 相似文献
999.
分叉煤层对比是地质勘探工作中的一个难题,朔县平原从普查阶段,对沉积环境进行了大量的研究,促进了6号及9号煤层分叉的对比工作。在详查阶段摸清了煤层分叉规律,9号煤层形成于滨海潟湖潮坪体系,6号煤层形成于水下三角洲平原体系,因海水进退,使9号煤层在西南方向分叉,6号煤层在35号勘探线以南分叉。在勘探阶段进一步证明预测的正确性。沉积环境的分析有力地提高了勘探质量,是行之有效的一种研究方法。 相似文献
1000.
基于缓冲区分析的城市化与地表水质关系研究——以烟台沿海区县为例 总被引:5,自引:0,他引:5
将城市化过程中的人为土地定义为建设用地,利用2004年TM影像得到烟台沿海区县建设用地数据。用缓冲区分析提取乡镇水平上建设用地比率和人口密度数据,缓冲半径从100m到2000m,利用ArcView空间分析功能对建设用地比率、人口密度、河网等级和水质进行叠置分析,并结合逐步回归分析方法揭示烟台沿海区县28个水质监测站各水质参量的空间变化情况。结果显示,通过建设用地比率和人口密度共同作用可以解释85%以上的水质参量模型,反映城市化的建设用地比率比人口密度能更好地解释水质参量的空间变化,大多数水质参量的最佳模型出现在2000m的缓冲半径上,表明建设用地比率和人口密度是影响研究区域水质的首要因素。同时,运用缓冲区分析等GIS空间分析方法为区域城市化进程与水环境质量的研究提供了新的途径。 相似文献