全文获取类型
收费全文 | 1997篇 |
免费 | 223篇 |
国内免费 | 178篇 |
专业分类
测绘学 | 544篇 |
大气科学 | 254篇 |
地球物理 | 566篇 |
地质学 | 354篇 |
海洋学 | 249篇 |
天文学 | 137篇 |
综合类 | 125篇 |
自然地理 | 169篇 |
出版年
2024年 | 8篇 |
2023年 | 5篇 |
2022年 | 16篇 |
2021年 | 33篇 |
2020年 | 61篇 |
2019年 | 59篇 |
2018年 | 53篇 |
2017年 | 68篇 |
2016年 | 81篇 |
2015年 | 70篇 |
2014年 | 123篇 |
2013年 | 141篇 |
2012年 | 78篇 |
2011年 | 118篇 |
2010年 | 102篇 |
2009年 | 134篇 |
2008年 | 125篇 |
2007年 | 153篇 |
2006年 | 134篇 |
2005年 | 104篇 |
2004年 | 88篇 |
2003年 | 89篇 |
2002年 | 90篇 |
2001年 | 67篇 |
2000年 | 64篇 |
1999年 | 48篇 |
1998年 | 48篇 |
1997年 | 37篇 |
1996年 | 40篇 |
1995年 | 29篇 |
1994年 | 26篇 |
1993年 | 22篇 |
1992年 | 31篇 |
1991年 | 8篇 |
1990年 | 14篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有2398条查询结果,搜索用时 15 毫秒
1.
本文介绍了GDJ跟踪打印经纬仪在人造卫星的观测中如何应用计算机对多圈卫星的目视观测资料进行实时采集、处理等工作过程的原理和方法。 相似文献
2.
A. Quirrenbach J. Larkin M. Barczys T. Gasaway C. Iserlohe A. Krabbe M. McElwain I. Song J. Weiss S. Wright 《New Astronomy Reviews》2006,49(10-12):639
OSIRIS (OH-Suppressing Infra-Red Integral-field Spectrograph) is a new facility instrument for the Keck Observatory. After seeing first light in February 2005, OSIRIS is currently undergoing commissioning. OSIRIS provides the capability of performing three-dimensional spectroscopy in the near-infrared z, J, H, and K bands at the resolution limit of the Keck II telescope, which is equipped with adaptive optics and a laser guide star. The science case for OSIRIS is summarized, and the instrument and associated data reduction software are described. 相似文献
3.
在BPL信道上增加数据广播内容的探讨 总被引:1,自引:1,他引:0
分析了现有罗兰C(包括BPL)在授时方面存在的不足,提出了在BPL信道上实现数据广播的主要目的。详细讨论了各种可能的数据信息的结构,并给出了有关参数和数据的计算方式和公式。认为发播内容的选择是由期望的系统功能决定的,广播内容的编排则与具体实现技术相关。最后给出了在不同调制方法下的传输速率,这是合理编排广播内容的基础。 相似文献
4.
5.
科技进步是测绘事业发展的动力 ,讨论运用科技进步的评价指标 ,对测绘单位的科技进步速度和对经济增长的贡献等进行测算和分析 ,可以为测绘规划管理及决策提供参考。 相似文献
6.
7.
根据我国测绘生产单位的实际情况 ,测绘项目管理的具体实施大致包括对项目的识别、选定、启动与筹集资金、计划、成本估算、执行计划、控制、收尾等主要步骤。当项目确定后 ,需要启动和筹集资金。而计划是项目管理的基本组成部分 ,包括明确项目目标和工作范围。项目成本估算有因素估算法和利用WBS方法的详细估算。项目质量管理规划的依据有质量目标、范围说明、标准和规范等。 相似文献
8.
9.
Neoliberalism and natural resource management: Agri-environmental standards and the governing of farming practices 总被引:1,自引:0,他引:1
Private standards and certification schemes are widely acknowledged as playing an increasingly important role in agri-environmental governance. While much of the existing research concludes that these mechanisms consolidate the global extension of neoliberalism – enhancing the power of corporate actors to the detriment of smaller producers – we argue that this overlooks the complex ways in which standards are used by governments and farmers in the governing of farming practices. Focusing specifically on a process standard – Environmental Management Systems (EMS) – promoted by the Australian government as a way of verifying the ‘clean and green’ status of agricultural exports, we examine how one regional group of producers has sought to use EMS standards in practice. Our analysis of a case study in the state of Victoria appears to confirm that EMS was a successful instrument for the extension of neoliberal governance, reinforcing the production of neoliberal subjectivities and practices amongst farmer participants and enabling the government to compensate for gaps in environmental provision. However, it would be a mistake to interpret the development of this EMS scheme as an example of naïve farmers manipulated by the state. In practice, farmers used the opportunities provided by government funding to undertake actions which expressed their own agri-environmental values and practices. Establishment of an EMS and associated eco-label enabled producers to demonstrate and extend their capacity to act as good environmental stewards. Our research highlights how the local application of environmental standards negotiates and shapes, rather than simply contributes to, neoliberal rule. 相似文献
10.
Information systems developed for different applications within the environmental domain have common characteristics, which can potentially be abstracted for sharing and reuse of design and software modules. This article presents an approach to designing for reuse by abstracting commonalities in the design of a Marine Information System (MIS), facilitating data management in a prototype operational monitoring, forecasting, and management system for the North Atlantic and the Nordic Seas. A detailed study of the requirements and data analysis was carried out, and Object-Oriented Technology (OOT) is employed to encapsulate abstractions and to promote reuse of code and design. This article identifies the Object-Oriented Frameworks (OOFW) required to build the MIS. It also provides guidelines to environmental scientists for restructuring legacy software and employing modern programming techniques. 相似文献