全文获取类型
收费全文 | 14511篇 |
免费 | 2955篇 |
国内免费 | 1668篇 |
专业分类
测绘学 | 562篇 |
大气科学 | 729篇 |
地球物理 | 8457篇 |
地质学 | 5190篇 |
海洋学 | 1533篇 |
天文学 | 22篇 |
综合类 | 769篇 |
自然地理 | 1872篇 |
出版年
2024年 | 76篇 |
2023年 | 244篇 |
2022年 | 465篇 |
2021年 | 573篇 |
2020年 | 640篇 |
2019年 | 712篇 |
2018年 | 537篇 |
2017年 | 600篇 |
2016年 | 586篇 |
2015年 | 608篇 |
2014年 | 858篇 |
2013年 | 871篇 |
2012年 | 888篇 |
2011年 | 904篇 |
2010年 | 781篇 |
2009年 | 836篇 |
2008年 | 853篇 |
2007年 | 991篇 |
2006年 | 1006篇 |
2005年 | 817篇 |
2004年 | 752篇 |
2003年 | 644篇 |
2002年 | 585篇 |
2001年 | 414篇 |
2000年 | 434篇 |
1999年 | 358篇 |
1998年 | 350篇 |
1997年 | 275篇 |
1996年 | 308篇 |
1995年 | 244篇 |
1994年 | 228篇 |
1993年 | 207篇 |
1992年 | 141篇 |
1991年 | 77篇 |
1990年 | 53篇 |
1989年 | 55篇 |
1988年 | 47篇 |
1987年 | 34篇 |
1986年 | 32篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 16篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1954年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
Linking vulnerability, adaptation, and resilience science to practice: Pathways, players, and partnerships 总被引:7,自引:1,他引:7
Coleen Vogel Susanne C. Moser Roger E. Kasperson Geoffrey D. Dabelko 《Global Environmental Change》2007,17(3-4):349-364
Vulnerability, adaptation and resilience are concepts that are finding increasing currency in several fields of research as well as in various policy and practitioner communities engaged in global environmental change science, climate change, sustainability science, disaster risk-reduction and famine interventions. As scientists and practitioners increasingly work together in this arena a number of questions are emerging: What is credible, salient and legitimate knowledge, how is this knowledge generated and how is it used in decision making? Drawing on important science in this field, and including a case study from southern Africa, we suggest an alternative mode of interaction to the usual one-way interaction between science and practice often used. In this alternative approach, different experts, risk-bearers, and local communities are involved and knowledge and practice is contested, co-produced and reflected upon. Despite some successes in the use and negotiation of such knowledge for ‘real’ world issues, a number of problems persist that require further investigation including the difficulties of developing consensus on the methodologies used by a range of stakeholders usually across a wide region (as the case study of southern Africa shows, particularly in determining and identifying vulnerable groups, sectors, and systems); slow delivery of products that could enhance resilience to change that reflects not only a lack of data, and need for scientific credibility, but also the time-consuming process of coming to a negotiated understanding in science–practice interactions and, finally, the need to clarify the role of ‘external’ agencies, stakeholders, and scientists at the outset of the dialogue process and subsequent interactions. Such factors, we argue, all hinder the use of vulnerability and resilience ‘knowledge’ that is being generated and will require much more detailed investigation by both producers and users of such knowledge. 相似文献
942.
The Stern Review on the Economics of Climate Change concluded that there can be “no doubt” the economic risks of business-as-usual (BAU) climate change are “very severe” [Stern, 2006. The Economics of Climate Change. HM Treasury, London, p. 188]. The total cost of climate change was estimated to be equivalent to a one-off, permanent 5–20% loss in global mean per-capita consumption today. And the marginal damage cost of a tonne of carbon emitted today was estimated to be around $312 [p. 344]. Both of these estimates are higher than most reported in the previous literature. Subsequently, a number of critiques have appeared, arguing that discounting is the principal explanation for this discrepancy. Discounting is important, but in this paper we emphasise that how one approaches the economics of risk and uncertainty, and how one attempts to model the very closely related issue of low-probability/high-damage scenarios (which we connect to the recent discussion of ‘dangerous’ climate change), can matter just as much. We demonstrate these arguments empirically, using the same models applied in the Stern Review. Together, the issues of risk and uncertainty on the one hand, and ‘dangerous’ climate change on the other, raise very strongly questions about the limits of a welfare-economic approach, where the loss of natural capital might be irreversible and impossible to compensate. Thus we also critically reflect on the state-of-the-art in integrated assessment modelling. There will always be an imperative to carry out integrated assessment modelling, bringing together scientific ‘fact’ and value judgement systematically. But we agree with those cautioning against a literal interpretation of current estimates. Ironically, the Stern Review is one of those voices. A fixation with cost-benefit analysis misses the point that arguments for stabilisation should, and are, built on broader foundations. 相似文献
943.
在厚覆盖区,目前的勘查技术在探测深度和精度方面已不能满足深部资源勘查的需求,地震方法可用来弥补目前勘查技术在寻找深部隐伏矿方面的某些不足。由于金属矿区的地质构造十分复杂,金属矿勘查中的地震方法技术是一个十分复杂的课题。这里结合在甘肃金昌铜镍多金属矿区的试验研究,讨论了地震方法技术在厚覆盖区探测隐伏超基性岩体和控矿构造的试验应用效果。 相似文献
944.
945.
Using the ground motion attenuation relation, we calculated and compared the effective peak acceleration (EPA) generated by main shocks and their strong aftershocks of 21 earthquake sequences with MS≥7 occurred in Chinese mainland and offing of China during 1966~2002. The result shows that EPA of strong aftershocks usually exceed that of main shock for 76.2% earthquake sequences and EPA of more than 50% strong aftershocks are greatly lar-ger than that of main shocks in large area, which suggests that it is necessary to take damage produced by strong aftershock into account in the probabilistic seismic hazard analysis and the seismic design. 相似文献
946.
947.
大底盘多塔楼结构的混合隔震控制 总被引:2,自引:0,他引:2
结合某实际工程,针对大底盘多塔楼结构提出混合隔震的控制策略,即对大底盘上的一栋或多栋塔楼采用隔震技术,并在隔震层附设一定数量的被动、主动或半主动的减震控制装置。建立了这种大底盘多塔楼结构混合隔震控制体系的运动方程,方程中各塔楼与下部结构及隔震层之间的刚度解耦,并考虑了隔震层的非线性。研究中比较了被动非线性粘滞阻尼器,半主动变孔隙阻尼器与理想主动控制时的减震控制效果。结果表明,这种混合隔震体系可以有效地减小上部塔楼与下部结构的地震反应,提高大底盘多塔楼结构的抗震安全性,取得明显的经济和社会效益。半主动变孔隙阻尼器可以极好地追踪理想主动控制力,取得与理想主动控制相近的减震控制效果。被动非线性粘滞阻尼器也能取得较好的减震效果,且易于维护,经济性较好,从工程应用的角度来看更为现实可行,具有较好的应用推广价值。 相似文献
948.
文中介绍了山区进行三维地震勘探的重要性及其方法原理。以山西晋城煤业集团某勘探区为实例进行实地勘探和试验,并对试验结果进行了详细的分析,进一步验证了该方法的可行性。 相似文献
949.
950.