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51.
The debate on genetic modification (GM) is persistent, polarized and mainly involves organized groups at the national level. With the European Union’s new policy of coexistence, commercial cultivation of GM crops is expected by the Dutch Ministry of Agriculture, Nature and Food Quality within the next few years, especially maize (BT) and potato (Phytophthera resistance and starch production). This makes the debate relevant for those directly confronted with this cultivation: the inhabitants of local rural communities. In The Netherlands, stakeholders formulated coexistence rules to prevent problems between conventional, organic and GM farmers that grow their crops in the same limited land area. Little is known, however, regarding the perceptions of the non-farming inhabitants of rural communities (“the neighbours”) in the debate. This paper presents the results of a focus group-based argumentative analysis of whether (and how) the GM issues play a decisive role among non-farming inhabitants of four rural communities in the Netherlands. We analysed the arguments in relation to a conceptual model that describes the potential rise and dynamics from a pre-Nimby ambivalence towards an outspoken Nimby position. We observed that the GM debate was given very little priority relative to other national issues on the political agenda and that more social cohesion correlates with fewer arguments in the national debate. It is argued that this mechanism keeps the Nimby ambivalence in an undetermined mode, which in turn diminishes the chances of radical rural-based protest against local GM cultivation of crops.  相似文献   
52.
Preserving soils is a major challenge in ensuring sustainable agriculture for the future. Soil erosion by water is a critical issue in the Mediterranean regions and usually occurs when high-erosive precipitation is in temporal association with poor vegetation cover and density. Modelling soil erosion risks over large spatial scales suffers from the scarcity of accurate information on land cover, rainfall erosivity and their intra-annual dynamics. We estimated the soil erosion risk on arable land in a Mediterranean area (Grosseto Province, southern Tuscany, Italy) and investigated its potential reduction as a response to the change in intra-annual distribution of land cover due to the increase of perennial forage crops. A GIS-based (R)USLE model was employed and a scenario analysis was performed by setting criteria for raising the performance of perennial forage crops. Statistical data on agricultural crops provided an insight into current intra-annual land cover dynamics. Rainfall erosivity was computed on the basis of 22-year hourly precipitation data. The model was used to: i) quantify the potential soil losses of arable land in the study area, ii) identify those areas highly affected by erosion risks iii) explore the potential for soil conservation of perennial crops, thereby enabling appropriate preventive measures to be identified. The erosion rates, averaged over an area of about 140’000 ha, are estimated to 33.42 Mg ha−1 y−1. More than 59% of the study area was subjected to soil losses higher than 11 Mg ha−1 y−1 (from moderate to severe erosion) and the highest rates are estimated for steep inland areas. Arable land with severe soil erosion rates (higher than 33 Mg ha−1 y−1) represent about 35% of the whole study area. The risk of soil loss by water erosion in the study area is estimated to be reduced on average by 36% if perennial crops are increased in terms of 35% of the total arable land. The soil erosion data produced compared well with the published local and regional data. This study thus provides useful preliminary information for landscape planning authorities and can be used as a decision support tool in quantifying the implications of management policies.  相似文献   
53.
I.Introducti0I1Hail1al1isthelargnsttropicalislal1dwitllabundal1t11aturalrcsourccssuitablef0rgrowtllgtrol,icalcropsand\\4t11ven'highp0tentia1pr0d,uctivity.Hotx'cY'cr,t11c1-ca1'cstillsomeproblemsf(l)Tl1ese1ectionoflandsuitableforfqrestisn0tstrictalldPreservativerateoftr0picalcr0psislow,(2)Mostoftropicalcr0psarecollccntratcdillthezoneofeastern"windgap"andnorthern"frigidplace"andtheirsecurityisnotstable,(3)Rubberareaaccountsforab0uttwo-thirdsoftl1etotalarea0ftropica1crops,henceproportiondis1ocat…  相似文献   
54.
Zhang  Yucui  Qi  Yongqing  Shen  Yanjun  Wang  Hongying  Pan  Xuepeng 《地理学报(英文版)》2019,29(6):909-921
Journal of Geographical Sciences - Based on the MODIS NDVI data and Landsat TM/ETM data of 2002 and 2012, this paper extracts the planting area of winter wheat—summer maize, single spring...  相似文献   
55.
虚拟水是当今水科学的研究热点,被认为是解决粮食与水资源安全的重要策略。在计算河南省2009年3种主要农作物生物需水量的基础上,结合作物单产得到初级产品单位虚拟水含量,明晰了这3种主要农作物的"虚拟水"空间分布格局。研究结果表明:河南省3种主要农作物中,棉花的单位虚拟水含量最高,玉米最小。空间上小麦的单位耗水量在三门峡最高,漯河最低;玉米的单位耗水量在三门峡最高,许昌最低;棉花的单位耗水量在鹤壁最高,信阳最低;3种作物单位虚拟水含量从东南向西北增加,尤其在东西方向最明显,但是不同作物又有细微差别。中东部水资源短缺区应提高玉米和小麦的种植面积,丘陵和山前平原单位耕地地表水丰富区可种植虚拟水含量较高的作物。提供了从虚拟资源视角认识水资源消耗的实证,可以对河南省农作物布局提供科学依据。  相似文献   
56.
基于NDVI时间序列影像的张掖市农作物种植结构提取   总被引:1,自引:0,他引:1  
HJ卫星(环境与灾害监测预报小卫星)数据具有较高的时间和空间分辨率,可以有效地进行农作物种类识别,利用其时间序列数据进行作物信息提取具有很大优势。以甘肃省张掖市为研究区,利用2012年4月~2012年10月15个时相的HJ卫星CCD(电荷耦合元件,charge-coupled device)数据,通过分析玉米、油菜、大麦和小麦农作物在整个生长阶段的时间序列NDVI(归一化植被指数,normalized difference vegetation index)变化特点,提取四类农作物NDVI随时间变化的特征曲线,利用决策树分类方法,对2012年张掖市农作物进行分类,并以外业调查得到的实际地面验证点对分类结果进行验证。验证结果表明,可以有效地识别玉米、油菜、大麦和小麦4类农作物,制图精度分别为94.74%、82.35%、78.95%和90%;总体分类精度达到86.43%。而后提取了张掖市2014年农作物种植面积和分布格局,通过对比分析发现,2012~2014年,张掖市玉米、油菜的种植面积有不同程度的增加,大麦和小麦的种植面积各有一定程度的较少。可以为张掖市主要作物的种植结构调整提供科学依据,还可以为黑河流域农作物信息提取研究提供参考。  相似文献   
57.
华北滹滏平原地下水位下降与灌溉农业关系   总被引:2,自引:0,他引:2       下载免费PDF全文
针对华北粮蔬主产区滹滏平原浅层地下水位不断下降成因问题,基于大量实测资料和相关分析方法与MapGIS技术,通过对近50年来区内地下水位、粮蔬播种强度、有效灌溉面积变化特征和降水量、气温变化下地下水位下降对粮蔬播种强度响应机制研究,结果表明:1980年前粮蔬播种强度每增加0.01或夏粮和蔬菜播种面积每增加1万hm2,研究区地下水位下降幅度为0.36 m或0.43 m;1980年以来随粮蔬播种强度增大,地下水位下降幅度明显增大,粮蔬播种强度每增加0.01或夏粮和蔬菜播种面积每增加1万hm2,地下水位降幅分别达0.69 m和1.15 m。不仅与因播种强度增大导致农业开采量增加有关,而且还与1980年以来降水量不断减少密切相关。降水量减少100 mm,区内农业开采量增加35.7 mm。  相似文献   
58.
气候变暖对西北干旱区农作物种植结构的影响   总被引:8,自引:2,他引:8  
采用年平均气温与冬小麦、春小麦、玉米和棉花种植面积的相关分析得出:年平均气温与新疆冬小麦种植面积呈显著负相关,与西北干旱区大部地方春小麦种植面积呈显著负相关,与西北干旱区大部地方玉米种植面积呈显著正相关,与新疆和甘肃河西棉花种植面积呈显著正相关。气候变暖、热量资源增加,使喜凉的春小麦和冬小麦种植面积呈迅速减少趋势,喜温的玉米和棉花种植面积呈迅速扩大,夏秋作物种植结构发生明显改变。  相似文献   
59.
SOTER支持下ALES模型对海南省热带作物适宜性评价研究   总被引:12,自引:0,他引:12  
在海南省1:25万SOTER数据库的支持下,根据联合国土地评价框架的有 关原则和概念,选取海南省4种热带作物建立了8种评价模型,运行ALES评价系统,得出不同气候条件下,不同土地利用状况下SOTER单元上作物适宜性评价指数,将此评价指数与GIS相连,可根据用户的要求输出评价成果。  相似文献   
60.
Perennial bioenergy crops with deep (>1 m) rooting systems, such as switchgrass (Panicum virgatum L.), are hypothesized to increase carbon storage in deep soil. Deeply rooted plants may also affect soil hydrology by accessing deep soil water for transpiration, which can affect soil water content and infiltration in deep soil layers, thereby affecting groundwater recharge. Using stable H and O isotope (δ2H and δ18O) and 3H values, we studied the soil water conditions at 20–30 cm intervals to depths of 2.4–3.6 m in paired fields of switchgrass and shallow rooted crops at three sites in the southern Great Plains of North America. We found that soil under switchgrass had consistently higher soil water content than nearby soil under shallow-rooted annual crops by a margin of 15%–100%. Soil water content and isotopic depth profiles indicated that hydraulic redistribution of deep soil water by switchgrass roots explained these observed soil water differences. To our knowledge, these are the first observations of hydraulic redistribution in deeply rooted grasses, and complement earlier observations of dynamic soil water fluxes under shallow-rooted grasses. Hydraulic redistribution by switchgrass may be a strategy for drought avoidance, wherein the plant may actively prevent water limitation. This raises the possibility that deeply rooted grasses may be used to passively subsidize soil water to more shallow-rooted species in inter-cropping arrangements.  相似文献   
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