全文获取类型
| 收费全文 | 3209篇 |
| 免费 | 758篇 |
| 国内免费 | 1466篇 |
专业分类
| 测绘学 | 269篇 |
| 大气科学 | 2252篇 |
| 地球物理 | 945篇 |
| 地质学 | 953篇 |
| 海洋学 | 586篇 |
| 天文学 | 36篇 |
| 综合类 | 215篇 |
| 自然地理 | 177篇 |
出版年
| 2024年 | 15篇 |
| 2023年 | 53篇 |
| 2022年 | 86篇 |
| 2021年 | 129篇 |
| 2020年 | 148篇 |
| 2019年 | 179篇 |
| 2018年 | 152篇 |
| 2017年 | 148篇 |
| 2016年 | 155篇 |
| 2015年 | 178篇 |
| 2014年 | 226篇 |
| 2013年 | 251篇 |
| 2012年 | 239篇 |
| 2011年 | 218篇 |
| 2010年 | 226篇 |
| 2009年 | 257篇 |
| 2008年 | 207篇 |
| 2007年 | 297篇 |
| 2006年 | 305篇 |
| 2005年 | 254篇 |
| 2004年 | 243篇 |
| 2003年 | 252篇 |
| 2002年 | 180篇 |
| 2001年 | 156篇 |
| 2000年 | 175篇 |
| 1999年 | 142篇 |
| 1998年 | 116篇 |
| 1997年 | 88篇 |
| 1996年 | 75篇 |
| 1995年 | 71篇 |
| 1994年 | 72篇 |
| 1993年 | 34篇 |
| 1992年 | 26篇 |
| 1991年 | 27篇 |
| 1990年 | 13篇 |
| 1989年 | 10篇 |
| 1988年 | 7篇 |
| 1987年 | 8篇 |
| 1986年 | 6篇 |
| 1985年 | 3篇 |
| 1984年 | 2篇 |
| 1983年 | 3篇 |
| 1982年 | 1篇 |
排序方式： 共有5433条查询结果，搜索用时 15 毫秒
1.
Stress wave attenuation across fractured rock masses is a great concern of underground structure safety. When the wave amplitude is large, fractures experience nonlinear deformation during the wave propagation. This paper presents a study on normal transmission of P‐wave across parallel fractures with nonlinear deformational behaviour (static Barton–Bandis model). The results show that the magnitude of transmission coefficient is a function of incident wave amplitude, nondimensional fracture spacing and number of fractures. Two important indices of nondimensional fracture spacing are identified, and they divide the area of nondimensional fracture spacing into three parts (individual fracture area, transition area and small spacing area). In the different areas, the magnitude of transmission coefficient has different trends with nondimensional fracture spacing and number of fractures. In addition, the study reveals that under some circumstances, the magnitude of transmission coefficient increases with increasing number of fractures, and is larger than 1. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
2.
After the survey of pollution sources, a study on surface water quality assessment and forecast is given by means of grey
system method, fuzzy mathematical method and multiple-index method. Based on it, aquatic environment quality features, treatment
measures and environmental strategies of the area are proposed. The quality of aquatic environment of 5 rivers in the Tumen
River area is studied. The results show that the pollution of surface water is serious; water quality of most rivers is between
grade IV and V except the Hunchun River, being higher than grade IV standard; pollution levels of most rivers have been basically
controlled except the of Burhatong River, which is deteriorating gradually. Pollutants of the rivers are comparatively regular,
mainly are SS, COD, BOD, AR-OH, NH3-N. The main pollution trades are chemical fibre industry, pulp and paper making industry and mining industry. If the growth
rate of gross industrial product is higher than 25 percent under the encouraging-model of regional exploitation, the pollutants’
load will overtake the bearing capacity of aquatic environment. Thus some protection program against pollution must be worked
out in order to achieve the harmonious development of economy society and environment.
A project from “Studies on Earlier Stage of Regional Development” of the Chinese Academy of Sciences 相似文献
3.
赵守尧 《成都信息工程学院学报》1994,(1)
本文使用天气学方法，从影响雅砻江区域主汛期降水量的长期预报有关因子出发，再运用数理统计方法反复筛选，仅取３个主要因子：西部青藏高原８个站冬春积温，北部冬季极涡面积指数，南部冬季印缅槽平均强度，建立逐步回归预报方程。结果显示：对主汛期６～９月降水量预报拟合准确率为１６／１７即约９４％。回归分析中发现：尽管西太平洋副热带高压对盆地西部降水有很大影响，盛夏且与高原积温有较密切相关，但由放大范围长时段的青藏高原积温，对于雅砻江区域主汛期降水量的影响超过西太平洋副热高压，因而在逐步回归过程中，副高因子仍被剔除． 相似文献
4.
对武汉区域气象中心并行计算机系统进行了详细地介绍，分析了并行计算机体系结构、网络和存储系统特点；给出了在并行计算机SP上实现数值预报业务并行化的部分结果；对数值预报模式在串、并行编程环境下的结果进行了分析比较。 相似文献
5.
利用西安数字地震遥测台网记录的数字地震资料，采用P波初动半周期残差法求得1998年7月临猗5．0级地震前后不同路径的Q(品质因子)值变化，发现在地震发生前Q值为87～203，震后Q值为67～164，震前震中区附近出现明显的高Q值异常。结果表明，地震前的高Q值异常可以作为地震预测的一种手段。 相似文献
6.
David P. Bacon Nash’at N. Ahmad Thomas J. Dunn Michael C. Monteith Ananthakrishna Sarma 《Natural Hazards》2008,44(3):317-327
By definition, a crisis is a situation that requires assistance to be managed. Hence, response to a crisis involves the merging
of local and non-local emergency response personnel. In this situation, it is critical that each participant: (1) know the
roles and responsibilities of each of the other participants; (2) know the capabilities of each of the participants; and (3)
have a common basis for action. For many types of natural disasters, this entails having a common operational picture of the unfolding events, including detailed information on the weather, both current and forecasted, that may impact on either
the emergency itself or on response activities. The Consequences Assessment Tool Set (CATS) is a comprehensive package of
hazard prediction models and casualty and damage assessment tools that provides a linkage between a modeled or observed effect
and the attendant consequences for populations, infrastructure, and resources, and, hence, provides the common operational
picture for emergency response. The Operational Multiscale Environment model with Grid Adaptivity (OMEGA) is an atmospheric
simulation system that links the latest methods in computational fluid dynamics and high-resolution gridding technologies
with numerical weather prediction to provide specific weather analysis and forecast capability that can be merged into the
geographic information system framework of CATS. This paper documents the problem of emergency response as an end-to-end system
and presents the integrated CATS–OMEGA system as a prototype of such a system that has been used successfully in a number
of different situations. 相似文献
7.
8.
9.
10.