首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   359篇
  免费   55篇
  国内免费   67篇
测绘学   30篇
大气科学   55篇
地球物理   58篇
地质学   92篇
海洋学   147篇
综合类   48篇
自然地理   51篇
  2024年   2篇
  2023年   8篇
  2022年   13篇
  2021年   13篇
  2020年   12篇
  2019年   14篇
  2018年   5篇
  2017年   11篇
  2016年   9篇
  2015年   8篇
  2014年   26篇
  2013年   16篇
  2012年   14篇
  2011年   12篇
  2010年   33篇
  2009年   13篇
  2008年   18篇
  2007年   32篇
  2006年   24篇
  2005年   23篇
  2004年   17篇
  2003年   22篇
  2002年   13篇
  2001年   13篇
  2000年   16篇
  1999年   16篇
  1998年   13篇
  1997年   11篇
  1996年   4篇
  1995年   18篇
  1994年   6篇
  1993年   9篇
  1992年   6篇
  1991年   4篇
  1990年   3篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
排序方式: 共有481条查询结果,搜索用时 85 毫秒
121.
贾开国 《地质找矿论丛》2005,20(Z1):166-169
文章通过瑞雷面波法在呼集高速公路路基病害调查中的工作实例及现场工作方法,论述了该技术在高速公路路基病害调查中的应用前景及推广价值.  相似文献   
122.
Atiqur Rahman 《GeoJournal》2006,65(3):211-227
The main objectives of the present study are: (i) to assess the income-wise household environmental conditions of the sampled households in Aligarh city, (ii) to examine income-wise disease profile of the population, (iii) to assess the relationship between income and four most occurring diseases, (iv) draw out inter-relationship between income, non-ideal household environmental conditions and environment related diseases. The quality of life and diseases in any urban areas get reflected by the immediate neighborhood in different parts of the city which depends upon the income strata of the households, their way of living, and their understanding of their household environment. This is because it is the household environment, which exerts the most and immediate influence on the life of the people. This study was carried out in order to assess household environmental conditions (i.e. housing conditions, bathroom and sanitation conditions, water supply conditions, water logging conditions, household garbage and solid waste, household pests, indoor air and indoor noise pollution) and their effect on the health of the resident population of Aligarh city. The method includes household survey of Aligarh city using questionnaires. The sampled households were classified into five income groups from very low to very high. Relationship was tested between income and household environmental conditions and also between income and diseases using Chi-Square technique. About 55% of the total sampled households suffer from diarrhea/dysentery, 43% jaundice, 42% malaria and 41% respiratory diseases. About 40% suffer from skin diseases, small pox/chicken pox. All these diseases are a result of poor household environmental conditions. Whereas 35% people reported other diseases (i.e. heart disease, hypertension and diabetes), only 14.42% households reported of tuberculosis. The study concludes that there exists a significant positive relationship between income level and household environmental conditions, and also between income and various diseases among sampled households of Aligarh city.  相似文献   
123.
吉林省西部是地方病高发地区,尤其是地方性氟、砷中毒的情况比较严重,尽管防氟改水工作已经进行40多年,但目前仍有相当多村屯的村民饮用高氟水,严重威胁人民的身体健康并影响当地的经济发展。针对现状作者分析了产生的原因并提出具体治理建议。  相似文献   
124.
The North Atlantic Younger Dryas climatic reversal did not cause a glacier advance on Mount Rainier. The glaciers on Mount Rainier seem to have advanced in response to regional or local shifts in climate. However, the Younger Dryas climatic reversal may have affected the Mount Rainier area, causing a cold, but dry, climate unfavorable to glacier advances. Glaciers in the vicinity of Mount Rainier advanced twice during late glacial/early Holocene time. Radiocarbon dates obtained from lake sediments adjacent to the corresponding moraines are concordant, indicating that the ages for the advances are closely limiting. The first advance occurred before 11,300 14C yr BP (13,200 cal yr BP). During the North Atlantic Younger Dryas event, between 11,000 and 10,000 14C yr BP (12,900 and 11,600 cal yr BP), glaciers retreated on Mount Rainier, probably due to a lack of available moisture, but conditions may have remained cold. The onset of warmer conditions on Mount Rainier occurred around 10,000 14C yr BP (11,600 cal yr BP). Organic sedimentation lasted for at least 700 years before glaciers readvanced between 9800 and 8950 14C yr BP (10,900 and 9950 cal yr BP).  相似文献   
125.
Canker and tip-dieback diseases have been found in field and greenhouse plantings ofProsopisbeing examined in agroforestry trials in South Texas. Several fungal species were associated with the field cankers, most notably aLasiodiplodiaand aPestalotiopsis. In the greenhouse, a tip-dieback as well as a canker disease that began at pruning cuts on the stock plants was seen.Pestalotiopsiswas most commonly isolated from these plants. Isolated cultures of theLasiodiplodiaand thePestalotiopsistogether with several other often associated fungi, (includingAlternariaFusarium) were tested for pathogenicity on young mesquite plants. OnlyLasiodiplodiaandPestalotiopsisproduced cankers under the conditions tested when spores were applied using wound inoculation techniques.Pestalotiopsisrequired high wound inoculation techniques.Pestalotiopsisrequired high humidity and proved much less damaging compared toLasiodiplodia, which closely mimicked the field symptoms. Benlate was found to give the greatest growth inhibition of these fungal pathogens inin vitrofungicide tests.  相似文献   
126.
1IntroductionSongbaiTown—thecapitaloftheShengnongjiaforestdistrictisthecenteroflocalpolitics,eco nomicsandculture ,anditisalsoanimportanttourismbase.Butinrecentyears,thelocalinhabi tantsinthisareahavesufferedfromcalculusdiseaseoccasionallyandthediseaseseemstobeofmoreandmorefrequentoccurrence .Thisnotonlycausesmasspanicandinfluencesnormalworkandstudyofthelocalpeople ,butalsobringsaboutnegativeeffectsontouristindustryofthisareaandrestrictsthedevelopmentoflocaleconomy .Inordertounderstandthesta…  相似文献   
127.
银川地区冠心病发病率气象预报模型   总被引:1,自引:1,他引:1       下载免费PDF全文
对银川地区冠心病与气象条件的分析表明,冠心病发病与气温、气压等气象要素有密切的关系。在相关分析的基础上,运用逐步回归方法建立冠心病周、旬发病率预报方程,为防病治病提供一些依据。  相似文献   
128.
在研究区生态系统中,岩石、粮作物中硒含量正常,而土壤、水、儿童患头发中硒含量明显不足;人体硒摄入量不足是该区大骨节病病情复发活跃的主要因素之一。采用有效的补硒措施,提高和改善人体硒水平是预防大骨节病复发的关键。  相似文献   
129.
新疆现有水库多兴建于20世纪60、70年代,经过了多年长期运行以及建设施工时的资金不足、技术条件差、施工方式落后等问题,部分水库已存在质量和安全隐患,成为病险水库。本文介绍了新疆水库建设的特点,重点分析了病险水库的成因机制,分类统计了垮坝事件的原因。并通过工程实例,针对不同的病因总结了病险水库的整治对策,从而为各种水库的类似病害提供了实践经验和技术方法。  相似文献   
130.
This article describes a web‐based data entry and GIS‐driven mapping system designed for an ethnographic and entomological survey of Chagas’ disease, an emerging zoonotic disease, and Triatoma dimidiata, a primary vector, in the Los Tuxtlas region of Veracruz, Mexico. To better understand this disease in the region, a collaborative, multi‐disciplinary study was initiated to conduct a spatial investigation of T. dimidiata and a community‐by‐community survey of local perceptions of the disease. In order to facilitate such a collaborative effort the CODES‐GIS was developed. This system allows for (near) real‐time mapping, analyses, disease reporting, and results sharing. CODES‐GIS provides a framework for a research team working in a remote area with limited technology, software, or GIS expertise to benefit from (near) real‐time spatial analyses performed at collaborating institutions. The system is bi‐directional, where field personnel can upload data to the system for field‐based map production. Likewise, laboratory personnel can upload diagnostics data for viewing by field personnel. In this way, the system provides a virtual link between the field and the laboratory to increase the speed at which results are returned to the local community. The CODES‐GIS is described along with a selection of study results.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号