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961.
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963.
964.
为了在新疆1∶50000矿产普查中研究成矿地质条件圈定成矿远景区域,在普查过程中通过重、磁、电等多种物探手段的综合应用,来探测深部和隐伏矿,效果明显。通过采集标本对其工作区的物性特征加以归纳分析,指导物探方法(重、磁、激电)的运用,为后续开展物探工作提供借鉴。首先在工作区利用重力和航磁资料,查明勘探区内地质构造特征及岩体分布规律,得到重、磁高值异常区多与岩体、岩体接触带及断裂带有关,而该区域的成矿与接触带或断裂构造密切相关,在接触带及断裂构造带上有利于硫化物发育,再利用大功率激发极化法的低阻高极化特征圈定含硫化物的有利区域,最后优选重、磁、电综合物探异常特征明显、成矿部位有利地段,并结合地质、化探异常特征对工作区定性的综合评价,指导寻找含硫化物的岩(矿)体,最终圈定找矿靶区一处,为矿产普查工作提供基础资料和找矿依据。 相似文献
965.
966.
《Marine Policy》2017
Emerging as an innovation for improving the management of overexploited fisheries around the world, rights-based fisheries management systems are being implemented in the form of either species- or area-based management. While there are numerous reviews on species-based management, there have been none on area-based management. To fill this gap, we undertake a critical review of the literature on area-based management systems known as “Territorial Use Rights for Fisheries” (or TURFs). Following an exhaustive search, seventy-nine peer-reviewed journal papers discussing the evolution, effectiveness, enforcement, and management context of TURFs were identified and selected. Review of these papers reveals that there is a growing interest in investigating the real-world effects of TURFs, both positive and negative. The variability in TURF performance appears to be due to design features, enforcement behavior of fishers, and specific contextual conditions, namely, biological fishery characteristics, socio-economic aspects of fishers, and institutional arrangements. The bulk of the published research has focused on theoretical analysis and empirical evidence based on fishers’ perception and experience. And there has been little research on enforcement issues or how design features and management contexts influence performance. This review emphasizes the need for rigorous empirical analyses of TURF effects, including assessment of the cost-effectiveness of different enforcement schemes and the effects of contextual conditions on TURF performance. Addressing current shortcomings in the literature could improve the design, implementation and performance of TURFs worldwide. 相似文献
967.
《Marine Policy》2017
For several decades, fishing sharks for their fins has provided important livelihoods for eastern Indonesian coastal communities that fish the Halmahera, Arafura and Timor Seas. Fishery and interview data collected in 2012-13 from three case studies on the islands of Seram, Aru and Rote were used to examine changes in shark fishers’ livelihoods over the preceding 20 years. While recent declines in catches and shark fin prices have had a substantial impact on fishers’ livelihoods, the fishery's low visibility in some areas of its geographic range and its political complexity in general have meant that government and international development agencies have largely been unaware of this impact. Many respondents remembered the Asian Financial Crisis in 1997-98 and the turn of the millennium as a time when sharks were still abundant and shark fin prices high, but were concerned about the on-going fall of shark fin prices since March 2012. High-value species, particularly guitarfish, hammerhead and sandbar sharks were most affected, losing up to 40% of their pre-2012 value. These changes, combined with the loss of fishing grounds, few attractive options for alternative income and restrictive debt relationships with shark fin bosses, have led some fishers to resort to high-risk activities such as blast fishing, illegal transboundary fishing, and people smuggling. This paper examines the multi-layered causes and consequences of fishers’ decision-making in response to adverse changes in their fishery, and explores options and obstacles to pursuing livelihoods that carry lower environmental, financial and personal risks. 相似文献
968.
《Marine Policy》2017
The literature on compliance in small scale fisheries provides evidence of the normative foundations of fishers’ behaviour. However, the mechanisms through which normative reasoning translates into non-compliance remains unclear due to the tendency to conceive non-compliant behaviour simply as an outcome of ‘moral deficit’. This paper identifies such mechanisms by focusing on moral reasons which undermine the legitimacy of fisheries regulations. Taking the case of Lake Victoria, East Africa, the paper explores how non-compliance can be founded on diverse and competing concepts of fairness by creating a typology of the modes of justification used by respondents who engage in illegal fishing. The paper establishes four areas of justification: the principle of superfluousness, the principle of autonomy, the principle of futility, and the principle of necessity. Investigating the evidence for each, the analysis finds that the majority of fisherfolk believe that regulations are necessary and support government action in fisheries management. However, fishers expressed futility in fishing legally, given the extent of illegal fishing, and justified their non-compliant behaviour through reference to the cost of legal fishing compared to illegal and the need for better catches and income associated with illegal fishing. 相似文献
969.
970.
为了提高阵列筏式波浪能发电装置采能效率,对不同排列方式的振荡浮子与不同楔形角的试验平台模型进行组合,优化水动力结构模型装置。建立了振荡浮子和采能装置试验平台三维模型,并进行了仿真分析。分别分析了由3种排列方式的振荡浮子和3种楔形角情况下的9种模型在水深15 m、平台吃水1.2 m、振荡浮子吃水0.5 m海况下垂直方向的时域响应和频域响应,结果发现当模型的振荡浮子以错开方式排列且试验平台楔形角为60°时,振荡浮子在垂直方向的振荡速度最快,其RAO值也最大,说明该组合模型更有利于提高筏式波浪能发电装置的采能效率。 相似文献