全文获取类型
收费全文 | 110篇 |
免费 | 16篇 |
国内免费 | 19篇 |
专业分类
测绘学 | 16篇 |
大气科学 | 24篇 |
地球物理 | 20篇 |
地质学 | 26篇 |
海洋学 | 33篇 |
天文学 | 1篇 |
综合类 | 8篇 |
自然地理 | 17篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 1篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1990年 | 2篇 |
1983年 | 1篇 |
排序方式: 共有145条查询结果,搜索用时 31 毫秒
71.
1:20万蒲圻幅化探水系沉积物测量,发现岳阳市东北区的F、As、Hg、Pb、Mo、U、Cu、Be、Sb等9种元素的过高或过低含量,有碍于人体健康,容易诱发相应的地球化学疾病;该环境中的B、Zn及Mo、Cu、As等5种元素,以及Cu/Mo比值的过高或过低,均有碍农业和林业的发展,会出现某些植物病虫害。因此,本文研究了该区的地球化学特征,划分出6个有碍人体健康、5个有碍农业与林业发展的综合预测区,并提出了防治措施与建议。 相似文献
72.
73.
在中国控制SARS(Severe Acute Respiratory Syndrome)疫情扩散与蔓延的大量科学实践活动基础上,从人地系统科学的理论和观点出发,提出了各种致病因子在人地互动过程中转移路径的逻辑模型,进而又提出了控制SARS疫情发展的人地互动逻辑模型。从后一个模型出发,把中国SARS疫情的发展规律归纳为5种传播模式,即异类病毒转移传播模式、家庭和社区接触传播模式、医院和门诊感染传播模式、市内随机扩散传播模式和飞点跳跃跨区传播模式。其中,跨区传播模式的影响最广泛、危害最巨大、控制起来最艰巨、复 相似文献
74.
气候变化对栾川工农业生产的影响 总被引:1,自引:0,他引:1
20世纪90年代以来,栾川县降水持续偏少,蒸发量增大,湿度减小,干旱发生的频率明显增多,强度加强。干旱导致的水资源紧缺,严重影响工业生产,造成粮食减产、农业生产成本加大、森林病虫害蔓延和森林火灾频发。加大植树造林、退耕还林的力度,调整农业产业结构,实施人工增雨,开发空中水资源,是应对气候变化的有效措施。 相似文献
75.
76.
The study of mathematical models for the spread of infectious diseases is an important issue in epidemiology. Given the fact
that most existing models cannot comprehensively depict heterogeneities (e.g., the population heterogeneity and the distribution
heterogeneity) and complex contagion patterns (which are mostly caused by the human interaction induced by modern transportation)
in the real world, a theoretical model of the spread of infectious diseases is proposed. It employs geo-entity based cellular
automata to simulate the spread of infectious diseases in a geographical environment. In the model, physical geographical
regions are defined as cells. The population within each cell is divided into three classes: Susceptible, Infective, and Recovered,
which are further divided into some subclasses by states of individuals. The transition rules, which determine the changes
of proportions of those subclasses and reciprocal transformation formulas among them, are provided. Through defining suitable
spatial weighting functions, the model is applied to simulate the spread of the infectious diseases with not only local contagion
but also global contagion. With some cases of simulation, it has been shown that the results are reasonably consistent with
the spread of infectious diseases in the real world. The model is supposed to model dynamics of infectious diseases on complex
networks, which is nearly impossible to be achieved with differential equations because of the complexity of the problem.
The cases of simulation also demonstrate that efforts of all kinds of interventions can be visualized and explored, and then
the model is able to provide decision-making support for prevention and control of infectious diseases.
Supported by Postdoctoral Foundation of China (Grant No. 20070410552) and Youth Fund of Institute of Policy and Management
(IPM), the Chinese Academy of Sciences (Grant No. O700481Q01) 相似文献
77.
Ballast water as a vector of coral pathogens in the Gulf of Mexico: the case of the Cayo Arcas coral reef 总被引:1,自引:0,他引:1
Aguirre-Macedo ML Vidal-Martinez VM Herrera-Silveira JA Valdés-Lozano DS Herrera-Rodríguez M Olvera-Novoa MA 《Marine pollution bulletin》2008,56(9):1570-1577
The discharge of nutrients, phytoplankton and pathogenic bacteria through ballast water may threaten the Cayo Arcas reef system. To assess this threat, the quality of ballast water and presence of coral reef pathogenic bacteria in 30 oil tankers loaded at the PEMEX Cayo Arcas crude oil terminal were determined. The water transported in the ships originated from coastal, oceanic or riverine regions. Statistical associations among quality parameters and bacteria were tested using redundancy analysis (RDA). In contrast with coastal or oceanic water, the riverine water had high concentrations of coliforms, including Vibrio cholerae 01 and, Serratia marcescens and Sphingomona spp., which are frequently associated with “white pox” and “white plague type II” coral diseases. There were also high nutrient concentrations and low water quality index values (WQI and TRIX). The presence of V. cholerae 01 highlights the need for testing ballast water coming from endemic regions into Mexican ports. 相似文献
78.
Murata S Takahashi S Agusa T Thomas NJ Kannan K Tanabe S 《Marine pollution bulletin》2008,56(4):641-649
Organotin compounds (OTs) including mono- to tri-butyltins, -phenyltins, and -octyltins were determined in the liver of adult sea otters (Enhydra lutris) found dead along the coasts of California, Washington, and Alaska in the USA and Kamchatka, Russia. Total concentrations of OTs in sea otters from California ranged from 34 to 4100ng/g on a wet weight basis. The order of concentrations of OTs in sea otters was total butyltins>total octyltins> or = total phenyltins. Elevated concentrations of butyltins (BTs) were found in some otters classified under 'infectious-disease' mortality category. Concentrations of BTs in few of these otters were close to or above the threshold levels for adverse health effects. Total butyltin concentrations decreased significantly in the livers of California sea otters since the 1990s. Based on the concentrations of organotins in sea otters collected from 1992 to 2002, the half-lives of tributyltin and total butyltins in sea otters were estimated to be approximately three years. 相似文献
79.
福建省养殖鳗鲡细菌性疾病的调查与防治 总被引:10,自引:0,他引:10
自1993年11月-1995年6月,对福建省养殖鳗鲡的细菌性疾病进行了调查,共调查到8种细菌病,本文介绍各种细菌病的流行病学。诊断方法及防治措施。 相似文献
80.
基于广州13个社区问卷调查数据,运用多元线性回归模型探讨老年人“旁路”就医距离特征及其影响因素,结果发现:1)广州老年人小病及慢性病旁路就医距离以1 km为“就地—旁路”临界点,以5 km为“近旁路—远旁路”临界点,形成核心—边缘旁路就医圈层;2)男性老年人比女性老年人旁路就医距离更远;3)居住社区类型是影响旁路就医距离的关键因素,医疗级配不均对旁路就医距离远近影响较大,也是城乡社区老年人旁路就医距离差异化的重要原因;4)对社区越满意的老年人更倾向选择社区内就地就医。倾向特征、使能资源和医疗需求共同影响老年人旁路就医行为的距离远近,进而影响老年人健康公平结果。 相似文献