首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   207篇
  免费   39篇
  国内免费   20篇
测绘学   31篇
大气科学   11篇
地球物理   30篇
地质学   52篇
海洋学   67篇
天文学   1篇
综合类   37篇
自然地理   37篇
  2024年   1篇
  2022年   7篇
  2021年   6篇
  2020年   8篇
  2019年   8篇
  2018年   4篇
  2017年   11篇
  2016年   11篇
  2015年   7篇
  2014年   12篇
  2013年   13篇
  2012年   17篇
  2011年   11篇
  2010年   21篇
  2009年   11篇
  2008年   15篇
  2007年   21篇
  2006年   7篇
  2005年   4篇
  2004年   4篇
  2003年   5篇
  2002年   3篇
  2001年   3篇
  2000年   2篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1995年   5篇
  1994年   5篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   3篇
  1987年   4篇
  1985年   10篇
  1984年   6篇
  1983年   8篇
  1982年   3篇
  1954年   1篇
排序方式: 共有266条查询结果,搜索用时 15 毫秒
61.
江苏省湿地资源丰富,湿地种类多样,分布广泛,但面临着严重的污染和破坏,且湿地立法相对分散,没有形成完整的湿地保护法律体系。《环境保护法》的修订,特别是生态红线、按日计罚、生态补偿、公益诉讼等制度设计,为江苏省湿地保护立法提供了强有力的制度支撑。在此情形下,制定"江苏省湿地保护条例"显得十分必要。  相似文献   
62.
Concerns about police militarization have become an important public policy issue since the aggressive police response to the 2014 protests in Ferguson, Missouri, where police officers used military-style equipment to confront protestors. This event was a stark visual reminder that many U.S. police departments have used federal programs to acquire surplus military equipment, including weapons, armored vehicles, and body armor. We explore the geographies and histories of one the most important programs, called 1033, which supplies police with military equipment under the rationale of prosecuting the War on Drugs. We show that the legal blurring of the police and the military has been ongoing for decades at the national scale but this has resulted in an uneven landscape of police militarization at the county scale. We also investigate one of the most common global arguments for why police become militarized, which is the presence of Special Weapons and Tactics-style paramilitary teams, finding little support for that claim. More geographic inquiry is needed to understand the trajectories, causes, and consequences of police militarization.  相似文献   
63.
基于3S技术和土地执法共同责任考核制度,设计满足共同责任考核计算规则的考核模型;结合深圳市规划土地数字监察平台,基于空间分析技术,建立土地执法共同责任考核系统,为实现全过程量化指标的土地执法共同责任考核模式提供更为准确、客观的参考依据及技术支撑。  相似文献   
64.
The resonance phenomenon of fluid motions in the gap between ship section, seabed and vertical quay wall is studied numerically and experimentally. The natural frequency of the fluid motions in the gap is derived. A two-dimensional time-domain coupled numerical model is developed to calculate the non-linear wave forces acting on a ship section against vertical quay in a harbor. The fluid domain is divided into an inner domain and an outer domain. The outer domain is the area between the left side of ship section and the incident boundary, where flow is expressed by Boussinesq equations. The rest area is the inner domain, which is the domain beneath the ship section plus the domain between the right side of ship section and vertical quay wall. The flow in the inner domain is expressed by Newton's Second Law. Matching conditions on the interface between the inner domain and the outer domain are the continuation of volume flux and the equality of pressures. The numerical results are validated by experimental data.  相似文献   
65.
In South Africa, fishery managers have struggled with a number of challenges in terms of compliance amidst a process of legal and policy reform since the democratic elections of 1994. The past 10 years, and more specifically the past five, have seen a significant change in compliance effort, with a particular focus on increasing law enforcement activities and capacity. This paper highlights two case studies that have been instrumental in restructuring fisheries compliance in South Africa. Although law enforcement has been significantly strengthened, greater political will and government commitment is required to implement alternative strategies that will have a long-term impact on levels of compliance.  相似文献   
66.
67.
A method is proposed for calculating the equivalent hydraulic conductivity (EHC) within a finite difference block (FDB). Application of the constant‐flux assumption of Darcy's Law, the EHC equals to the integration of effective hydraulic conductivity (Kw) as a function of pressure head (hw) divided by the head difference at the ends of the FDB. Error analysis show that the constant‐flux (CF) EHC estimates are better than those computed by the commonly used arithmetic‐mean (AM), geometric‐mean (GM), and harmonic‐mean (HM) techniques. CF EHC results are even more superior at larger interblock head difference situations. Simulations of water infiltration experiments show that simulations using the CF EHC or AM or GM weighting technique have only slight difference while applying the Neumann type boundary condition at the ground surface. In case of the Dirichlet type boundary condition, however, the CF EHC is superior to the other two in correctly estimating the depth of infiltration while enlarging the grid size. Therefore, it is recommended to adopt the CF EHC with a larger grid size to the more stable and more efficient results. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
68.
本文分析益阳市赫山区全区砖厂数量多、分布密、产能低、污染大,部分已没有可开采资源的现状;分析砖厂办理采矿许可证延续手续主动性不高和砖厂难以关停的原因;介绍在砖厂执法工作中的几点经验做法。  相似文献   
69.
阮于洲 《东北测绘》2012,(3):219-220
分析了新时期测绘发展面临的新形势,对《中华人民共和国测绘法》规定的有关概念内涵、管理体制、运行机制、准入制度等的适应性进行了探讨,对进一步修订《中华人民共和国测绘法》提出了建议。  相似文献   
70.
王强先 《山东地质》2010,(5):55-56,59
为应对国际金融危机,平度市国土资源局积极响应国土资源部在全国范围内部署开展的"保增长、保红线"双保行动,立足部门职能,扎实工作,加强和改善土地宏观调控新机制,有效保障扩大内需,保障重点项目用地,促进经济平稳较快发展。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号