全文获取类型
收费全文 | 10105篇 |
免费 | 2244篇 |
国内免费 | 723篇 |
专业分类
测绘学 | 283篇 |
大气科学 | 91篇 |
地球物理 | 7458篇 |
地质学 | 3060篇 |
海洋学 | 514篇 |
天文学 | 25篇 |
综合类 | 464篇 |
自然地理 | 1177篇 |
出版年
2024年 | 15篇 |
2023年 | 73篇 |
2022年 | 236篇 |
2021年 | 306篇 |
2020年 | 370篇 |
2019年 | 449篇 |
2018年 | 349篇 |
2017年 | 346篇 |
2016年 | 296篇 |
2015年 | 357篇 |
2014年 | 459篇 |
2013年 | 557篇 |
2012年 | 550篇 |
2011年 | 578篇 |
2010年 | 481篇 |
2009年 | 571篇 |
2008年 | 599篇 |
2007年 | 717篇 |
2006年 | 732篇 |
2005年 | 609篇 |
2004年 | 612篇 |
2003年 | 528篇 |
2002年 | 441篇 |
2001年 | 340篇 |
2000年 | 358篇 |
1999年 | 304篇 |
1998年 | 290篇 |
1997年 | 238篇 |
1996年 | 275篇 |
1995年 | 212篇 |
1994年 | 202篇 |
1993年 | 180篇 |
1992年 | 113篇 |
1991年 | 70篇 |
1990年 | 51篇 |
1989年 | 54篇 |
1988年 | 46篇 |
1987年 | 32篇 |
1986年 | 26篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 16篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1954年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
181.
According to the principle of the eruption of debris flows, the new torrent classification techniques are brought forward. The torrent there can be divided into 4 types such as the debris flow torrent with high destructive strength, the debris flow torrent, high sand-carrying capacity flush flood torrent and common flush flood by the techniques. In this paper, the classification indices system and the quantitative rating methods are presented. Based on torrent classification, debris flow torrent hazard zone mapping techniques by which the debris flow disaster early-warning object can be ascertained accurately are identified. The key techniques of building the debris flow disaster neural network (NN)real time forecasting model are given detailed explanations in this paper, including the determination of neural node at the input layer, the output layer and the implicit layer, the construction of knowledge source and the initial weight value and so on. With this technique, the debris flow disaster real-time forecasting neural network model is built according to the rainfall features of the historical debris flow disasters, which includes multiple rain factors such as rainfall of the disaster day, the rainfall of 15 days before the disaster day, the maximal rate of rainfall in one hour and ten minutes. It can forecast the probability, critical rainfall of eruption of the debris flows, through the real-time rainfall monitoring or weather forecasting. Based on the torrent classification and hazard zone mapping, combined with rainfall monitoring in the rainy season and real-time forecasting models, the debris flow disaster early-warning system is built. In this system, the GIS technique, the advanced international software and hardware are applied, which makes the system′s performance steady with good expansibility. The system is a visual information system that serves management and decision-making, which can facilitate timely inspect of the variation of the torrent type and hazardous zone, the torrent management, the early-warning of disasters and the disaster reduction and prevention. 相似文献
182.
This is the second part of a contribution to the debate on the possibilities of leveraging economic globalisation — through incorporation in international production networks and global commodity chains (GCCs) — as a strategy for developing countries to industrialise and advance their position in the world economy. In the first part, we analysed the experience of the East Asian apparel industry and addressed the issues of sustaining positions, upgrading to more rewarding roles, and advancing to less dependent positions within production networks and GCCs. We developed an analytical framework at both the firm and industry levels, and subsequently identified alternative firm- and industry-level strategies and trajectories. The present paper deals with these issues in the context of the Singapore apparel industry. Based on extensive empirical research, we demonstrate that although the East Asian experience of upgrading and repositioning within the GCC is to some extent emulated in the case of the Singapore apparel industry, the outcomes have been less favourable in terms of the depth, extent and strength of these trajectories. The differing outcomes can be explained in terms of different (systemic) conditions in the Singapore business environment, including the agency of local players, the geography of sourcing networks, and the role of the state and prevailing business attitudes. Our conclusions merit continued attention in both research and policy circles on the development of capabilities at the firm level, and the role of local business and institutional environments in local industry development processes under globalisation. 相似文献
183.
184.
185.
186.
187.
188.
189.
Yan Y. Kagan 《Geophysical Journal International》2002,149(3):731-754
190.