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   2153篇
  免费   77篇
  国内免费   26篇
测绘学   65篇
大气科学   186篇
地球物理   545篇
地质学   766篇
海洋学   175篇
天文学   326篇
综合类   12篇
自然地理   181篇
  2021年   27篇
  2020年   24篇
  2019年   26篇
  2018年   62篇
  2017年   38篇
  2016年   62篇
  2015年   38篇
  2014年   61篇
  2013年   112篇
  2012年   64篇
  2011年   115篇
  2010年   84篇
  2009年   96篇
  2008年   100篇
  2007年   85篇
  2006年   68篇
  2005年   77篇
  2004年   50篇
  2003年   45篇
  2002年   65篇
  2001年   43篇
  2000年   54篇
  1999年   60篇
  1998年   38篇
  1997年   50篇
  1996年   44篇
  1995年   35篇
  1994年   33篇
  1993年   34篇
  1992年   23篇
  1991年   22篇
  1990年   23篇
  1989年   14篇
  1988年   14篇
  1987年   34篇
  1986年   22篇
  1985年   27篇
  1984年   31篇
  1983年   28篇
  1982年   37篇
  1981年   23篇
  1980年   29篇
  1979年   21篇
  1978年   19篇
  1977年   22篇
  1976年   21篇
  1975年   26篇
  1974年   18篇
  1973年   18篇
  1971年   13篇
排序方式: 共有2256条查询结果,搜索用时 15 毫秒
991.
We describe the results of a model dynamic simulation of the formation and support of a narrow prominence at the apex of a coronal magnetic loop or arcade. The condensation process proceeds via an initial radiative cooling and pressure drop, and a secondary siphon flow from the dense chromospheric ends. The anti-buoyancy effect as the prominence forms causes a bending of the confining magnetic field, which propagates toward the semi-rigid ends of the magnetic loop. Thus, a wide magnetic hammock or well (of the normal-polarity Kippenhahn-Schlüter-type) is formed, which supports the prominence at or near the field apex. The simplicity of this 1.5-dimensional model, with its accompanying diagnostics, allows one to comprehend the various contributions to the nonlinear dynamics of prominence condensation and levitation.  相似文献   
992.
Approximate solutions of the linearized non-adiabatic MHD equations, obtained using the ballooning method, are compared with exact numerical solutions of the full equations (including the effects of optically thin plasma radiation). It is shown that the standard ballooning method, developed within the framework of ideal linear MHD, can be generalized to non-ideal linear MHD. The localized (ballooning) spectrum has to be used with caution, but can give valuable (though limited) information on non-ideal stability.The numerical analysis also confirms and quantifies the interesting connection between magnetic and thermal instabilities. The existence of such a coupling is inherent in many qualitative discussions of magnetic disruptions. Finally, the hitherto unrecognized role of the thermal continuum in the unstable part of the magnetothermal spectrum is investigated.Research Assistant of the National Fund for Scientific Research, Belgium.  相似文献   
993.
994.
995.
996.
The lack of broad public support prevents the implementation of effective climate policies. This article aims to examine why citizens support or reject climate policies. For this purpose, we provide a cross-disciplinary overview of empirical and experimental research on public attitudes and preferences that has emerged in the last few years. The various factors influencing policy support are divided into three general categories: (1) social-psychological factors and climate change perception, such as the positive influences of left-wing political orientation, egalitarian worldviews, environmental and self-transcendent values, climate change knowledge, risk perception, or emotions like interest and hope; (2) the perception of climate policy and its design, which includes, among others, the preference of pull over push measures, the positive role of perceived policy effectiveness, the level of policy costs, as well as the positive effect of perceived policy fairness and the recycling of potential policy revenues; (3) contextual factors, such as the positive influence of social trust, norms and participation, wider economic, political and geographical aspects, or the different effects of specific media events and communications. Finally, we discuss the findings and provide suggestions for future research.

Policy relevance

Public opinion is a significant determinant of policy change in democratic countries. Policy makers may be reluctant to implement climate policies if they expect public opposition. This article seeks to provide a better understanding of the various factors influencing public responses to climate policy proposals. Most of the studied factors include perceptions about climate change, policy and its attributes, all of which are amenable to intervention. The acquired insights can thus assist in improving policy design and communication with the overarching objective to garner more public support for effective climate policy.  相似文献   

997.
The feasibility of green growth is studied in the context of climate change. As carbon emissions are easier to quantify than many other types of environmental pressure, it will be possible to reach a more definite conclusion about the likelihood of green growth than has been possible in the long-standing historical debate on growth versus the environment. We calculate the rate of decoupling between gross domestic product (GDP) and GHG emissions needed to achieve internationally agreed climate targets. Next, eight arguments are considered that together suggest that fast decoupling will be very difficult. Subsequently, we examine the main lines of research used by proponents of green growth to support their viewpoint, including theoretical arguments, exercises with integrated assessment models, and studies of the environmental Kuznets curve hypothesis. It will be concluded that decoupling as a main or single strategy to combine economic and environmental aims should be judged as taking a very large risk with our common future. To minimize this risk we need to seriously consider reducing our dependence on growth. This requires a fundamental change of focus in both economic research and policy.

Policy relevance

Currently, green growth is the only strategy of mainstream economists and policy makers to address climate change. This article demonstrates that such an exclusive focus is very risky due to the scale of the challenge and the existence of various barriers to the fast decoupling of GHG emissions from economic output. It seems that the only option to combine environmental and economic objectives is reducing the dependence of our economies on growth. Finding strategies in line with this requires a fundamental change of focus in both economic research and policy.  相似文献   

998.
999.
The transverse current anomalies evident from magnetotelluric sounding (MTS) data in the transition zone from the Asian continent to the Pacific Ocean and a geoelectrical model suitable for explaining these effects are discussed. Using simulation results and new MTS data on Sakhalin and northern Vietnam, ultra-deep fluid–fault system (UDFFS) models are constructed, comprising steeply dipping low-resistivity and high-resistivity linear bodies which penetrate through the whole section of the lithosphere, continuing deep into the asthenosphere. The structure of these systems reflects the development of deep and ultra-deep fault zones, along which mantle-originated fluids may migrate through sediments to reach the surface. This allows the anisotropic–conductive fractured structures adjacent to these faults to be considered as being most favorable for hydrocarbon accumulations.  相似文献   
1000.
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