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51.
Mark A. Kaemingk Tracy L. Galarowicz John A. Clevenger David F. Clapp 《Journal of Great Lakes research》2011,37(4):625-631
Fish movement may vary across a wide array of aquatic ecosystems and may be related to the overall size of the system inhabited. We investigated movement of smallmouth bass in Lake Michigan because this information is lacking for larger systems. A total of 16 smallmouth bass were surgically implanted with ultrasonic transmitters within the Beaver Archipelago, northern Lake Michigan. During 2007-2008, a maximum of one location per individual was recorded daily during three specific tracking periods - pre-spawn, spawning, and post-spawn - to determine diurnal movement patterns. Movement was evaluated as site fidelity, minimum displacement rate, maximum excursion rate, and distance from shore. Smallmouth bass exhibited greater maximum excursion rates during the spawn period compared to pre-spawn. Movement rates did not differ between tracking periods; however, movement rates were greater during the spawn period in 2007 than 2008. Both sexes moved further offshore to deeper water during post-spawn, but females were located further offshore than males during this period. Annual site fidelity was more evident during post-spawn than during spawning for both sexes. Two smallmouth bass emigrated outside of the Archipelago, suggesting this population may be more “open” in terms of individuals moving throughout northern Lake Michigan than previously thought. These results indicate smallmouth bass may move greater distances in larger aquatic systems and therefore larger management units (in terms of total area) should be established in Lake Michigan to account for these greater excursion distances. 相似文献
52.
Peter D. Blanken Christopher Spence Newell Hedstrom John D. Lenters 《Journal of Great Lakes research》2011,37(4):707-716
The surface energy balance of Lake Superior was measured using the eddy covariance method at a remote, offshore site at 0.5-h intervals from June 2008 through November 2010. Pronounced seasonal patterns in the surface energy balance were observed, with a five-month delay between maximum summer net radiation and maximum winter latent and sensible heat fluxes. Late season (winter) evaporation and sensible heat losses from the lake typically occurred in two- to three-day-long events, and were associated with significant release of stored heat from the lake. The majority of the evaporative heat loss (70-88%) and sensible heat loss (97-99%) occurred between October and March, with 464 mm (2008-2009) and 645 mm (2009-2010) of evaporative water loss occurring over the water year starting October 1. Evaporation was proportional to the horizontal wind speed, inversely proportional to the ambient vapor pressure, and was well described by the ratio of wind speed to vapor pressure. This ratio remained relatively constant between the two water years, so the differences in evaporative water loss between years were largely associated with differences in lake surface conditions (e.g. water temperature, ice cover, and ice duration). Since late-season water temperature decline is driven by evaporative and sensible heat loss, the potential for a negative feedback mechanism between evaporation and ice cover is discussed. 相似文献
53.
南四湖水利管理局自2006年以来按照国务院水管体制改革实施意见和水利部水管体制改革实施方案要求,全面推行了水利工程管理和维修养护分离。总结了水管体制改革取得的显著成效,结合基层工作实际分析了管理和养护运作过程中存在的一些问题,提出了完善措施及建议。 相似文献
54.
青海湖生态环境演变与稳定性 总被引:1,自引:0,他引:1
根据长系列水文模型模拟结果,对青海湖的环境演变进行了分析,利用一阶周期性自回归模型对青海湖水位变化趋势及其对湖泊生态的影响进行了预测。结果表明:青海湖多年平均亏缺水量为3.31亿m3,近10 a来增温幅度较大时期的亏缺水量为5.19亿m3;保持青海湖生态稳定的关键物种为青海湖裸鲤,盐度是决定青海湖裸鲤繁殖和生长的关键环境要素,其阈值为16.8‰;考虑气候变化的影响时,青海湖水位在未来30 a会继续下降,水位阈值为3 190.25 m,2030年水位最低,为3 191.35 m,此后水位开始小幅度回升并逐渐趋稳;不考虑气候变化的影响时,预计未来30 a内青海湖水位仍会持续下降,之后下降趋势开始变缓并趋于稳定,2100年左右稳定在3 192.25 m;两种预测结果都没有下降到青海湖生态稳定的水位阈值,因此未来青海湖生态系统的稳定性不受影响。 相似文献
55.
鄱阳湖水资源保护规划研究 总被引:1,自引:0,他引:1
随着鄱阳湖区经济快速发展,工业废水和生活污水排放量增长较快,入湖污染负荷也相应增加。为了做好鄱阳湖水资源保护规划,在分析2004~2008年鄱阳湖湖区国家控制点监测资料的基础上,针对目前鄱阳湖存在的主要水污染问题,研究提出了鄱阳湖水资源保护目标与布局;通过分析鄱阳湖入湖污染负荷的来源和纳污能力,确定了污染物控制量和削减量;为有效地控制入湖污染负荷,提出了鄱阳湖水资源保护对策与措施。 相似文献
56.
洞庭湖是长江洪水的天然调蓄场所,不仅承接湘、资、沅、澧四水水沙,还纳入由荆江三口分泄的长江水沙,经湖泊调蓄后由城陵矶注入长江,形成了复杂的江湖关系,需要加强流域统一管理。通过分析洞庭湖区自然、经济状况及湖区湿地情况,结合1998年大水后湖区的治理情况及三峡工程蓄水运用后江湖关系的新变化,深入分析湖区湿地生态环境所面临的诸多问题,探讨如何在新一轮洞庭湖综合治理过程中,科学处理湖区综合治理与湿地生态环境保护与修复的关系。提出了洞庭湖统一管理措施,以便有效保护洞庭湖湿地生态环境与资源。 相似文献
57.
58.
在已有的艾比湖保护与改善措施的基础上,根据2000年以来艾比湖入湖水量与水域面积变化资料,补充分析水域面积变化的主导因素,提出确立艾比湖生态水权,开征生态环境保护税,建立生态环境补偿机制的建议,从制度层面上更加有效地为实现艾比湖生态环境保护的目标提供保障. 相似文献
59.
2009年5-9月,对晋阳湖的浮游生物及水质进行了调查,结果表明:晋阳湖共有浮游植物47种,浮游植物生物量为100.63 mg/L,浮游动物30种,生物量0.304 mg/L,水质类型为SCⅡa型。晋阳湖处于富营养化状态。 相似文献
60.
调查表明,超标准洪水、闸门缺陷和与生俱来的设计问题导致了2010年7月爱荷华州德里湖大坝的溃决。漫顶引起了土坝侵蚀,并最终泄空了德里湖水库,造成了数百万美元的财产损失。 相似文献