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201.
城市空气质量与经济建设及人民生活息息相关,是政府和人民关注的重大社会问题。利用库尔勒市2014年9月1日-2015年8月31日州政府、棉纺厂、开发区三个环境监测站逐时观测资料,分析了库尔勒市空气质量等级和首要污染物的时空分布,并分析了污染天气发生的日变化特征。结果表明:(1)三站污染天气出现频率分别为49.4%、40.9%和34.7%,符合州政府>棉纺厂>开发区的分布规律。三站污染天气均是春季出现频率最高,分别占到44.7%,39.4%和48.5%,其次为秋季、冬季和夏季;(2)库尔勒市首要污染物中, PM10的频率最高,其次为PM2.5,CO、NO2、O3及SO2出现频率均低于10.0%。PM10作为首要污染物在春季出现频率最高,三站出现频率为33.9%-36.3%,PM2.5则是冬季出现频率最高,三站出现频率为59.1%-86.4%;(3)库尔勒市污染天气和重污染天气发生频率符合傍晚与夜间高,白天低的变化规律。污染天气发生频率最高值出现在0:00时,最低值出现在6:00-7:00时,重污染天时延迟到9:00时。上述结果表明库尔勒市春季周边自然污染源的排放与输送对该市的空气质量影响巨大。  相似文献   
202.
近200年来黑河下游天鹅湖湖泊沉积记录的环境变迁   总被引:12,自引:2,他引:12  
根据2002-2004年洞庭湖水质监测数据,参照GB3838-2002中Ⅲ类水质标准,选用内梅罗水污染指数法和黄浦江污染指数对洞庭湖水质现状进行评价,结果表明:(1)洞庭湖水体的主要污染指标是总磷,总氮和粪大肠菌群;(2)黄浦江污染指数平均值为0.27,所以洞庭湖12个断面水质无黑臭现象发生;(3)枯水期西洞庭湖和南洞庭湖水质污染最严重,平水期西洞庭湖水质污染最严重,洞庭湖丰水期的污染程度小于平水期;(4)洞庭湖的大部分水体的水质主要处于轻度污染的状态,局部水体的水质在枯水期达到重污染的状态.  相似文献   
203.
辽宁中部城市群大气能见度变化趋势及影响因子分析   总被引:33,自引:5,他引:33  
通过分析辽宁中部相对集中分布的5个城市群1987-2002年间的大气能见度、影响能见度的气象因子和污染物的变化特征及能见度与气象因子、污染物浓度之间的相关关系等,得到以下结论:(1)各城市能见度有明显的月、季和年际变化特征,能见度月变化呈双峰型,第一个峰值在5月份,第二个峰值在9,10月份;冬季能见度的值最低,春、秋季高;本溪市的能见度在逐年变好;沈阳的能见度从1987-1997年逐年变好,1997年以后又逐年变差;其它城市的能见度呈逐年变差的趋势。(2)各城市影响能见度的气象因子的年际变化特征基本是一致的;5个城市TSP,SO2污染浓度年均值均呈下降趋势,NOx的年际变化趋势不明显。(3)能见度与湿度、雾的相关关系都呈负相关且非常显著;与降雨量、风速及温度之间的关系比较复杂;与各种污染物的相关都呈负相关。  相似文献   
204.
封闭体系有机质与有机碳氢氮恢复动力学研究   总被引:3,自引:0,他引:3  
在封闭体系的条件下,对典型的Ⅰ、Ⅱ、Ⅲ型干酪根在热演化过程中的损失进行生烃动力学研究,获得了Ⅰ、Ⅱ、Ⅲ型干酪根的总量、有机碳、氢以及氮质量损失动力学参数。用Kinetics软件计算了封闭体系干酪根有机碳丰度、氢碳原子比和氮碳原子比的恢复系数。认为在对高成熟—过成熟干酪根进行生烃评价时,Ⅰ、Ⅲ型干酪根残余有机碳丰度需要进行恢复,而Ⅱ型干酪根残余有机碳丰度不需要恢复。三种类型干酪根的氢碳原子比均需要进行恢复。  相似文献   
205.
The carbonaceous chondrite meteorites are fragments of asteroids that have remained relatively unprocessed since the formation of the Solar System 4.56 billion years ago. The major organic component in these meteorites is a macromolecular phase that is resistant to solvent extraction. The information contained within macromolecular material can be accessed by degradative techniques such as pyrolysis. Hydropyrolysis refers to pyrolysis assisted by high hydrogen gas pressures and a dispersed sulphided molybdenum catalyst. Hydropyrolysis of the Murchison macromolecular material successfully releases much greater quantities of hydrocarbons than traditional pyrolysis techniques (twofold greater than hydrous pyrolysis) including significant amounts of high molecular weight polyaromatic hydrocarbons (PAH) such as phenanthrene, carbazole, fluoranthene, pyrene, chrysene, perylene, benzoperylene and coronene units with varying degrees of alkylation. When hydropyrolysis products are collected using a silica trap immersed in liquid nitrogen, the technique enables the solubilisation and retention of compounds with a wide range of volatilities (i.e. benzene to coronene). This report describes the hydropyrolysis method and the information it can provide about meteorite macromolecular material constitution.  相似文献   
206.
Fifteen recent sediment samples from the offshore Orinoco Delta, Venezuela, were separated by sieving and pipette analysis into seven size fractions ranging from 4ø to 10ø, in 1 ø units. Total organic carbon was determined for each size fraction and the organic matter characterized by pyrolysis and pyrolysis-gas chromatography. The sediments average 0.98% organic matter with somewhat higher values nearshore. Nearshore sediments also had higher organic contents in the coarsest fractions and a decrease in organic matter from coarse to fine sediment fractions. Sediments from further offshore generally show the highest organic contents in the finer fractions. Pyrolysis showed a low bitumen content and confirmed that the kerogen was dominantly terrestrial and gas prone. The observed trends were attributed to sorting of organic matter by its physical characteristics, with the denser, coarse-grained material settling out nearshore and the Finer-grained material being carried further from shore and settling out with finer-grained sediments.  相似文献   
207.
张强凹陷长北背斜侏罗系上统有沙海组和九佛堂组两套生油合系,其有机质丰度属中等,沙海组生油岩多为腐泥腐殖型.地球化学分析表明,沙海组下段的生油岩处于低熟—成熟阶段,该地区各层原油主要来源于侏罗系上统沙海组下段生油岩.  相似文献   
208.
Heavy metal and organic pollutants in sediments along the coastal zone of southeastern China have been investigated. Sediment samples are retrieved from three depositional environments: coast, estuary, and tide-affected river mouth. The relative abundance of heavy metal and organic pollutants is related to their geochemical properties as well as depositional environments and anthropogenic discharge. Based on a sequential extraction method, it is revealed that anthropogenic Pb, Cr, Cu, and Cd are mainly bound to Fe–Mn oxides, suggesting that adsorption and co-precipitation of Fe–Mn oxides are in the control of their transfer processes from water column to sediment. Heavy metal bound to carbonates is also an important pool especially for Cd, Mn, and Pb. The main organic pollutants found in the study area include petroleum-related alkanes, phthalic acid ester, organic silicon, chlorophenol, phenyl ether, and amine. The accumulation of heavy metals and organics in surficial sediments has a decrease tendency from estuarine environment to coastal environment and to tide-affected river mouth.  相似文献   
209.
The reactive transport modeling of a complicated suite of reactions apparent in the aquifer during the application of N-containing fertilizers is reported. The unconfined sandy aquifer can be subdivided into an oxic zone which contains groundwater with oxygen and nitrate and an anoxic zone characterized by elevated iron and sulfate concentrations in groundwater. Oxygen and nitrate are being reduced by pyrite and organic matter that commonly apparent in the aquifer. The oxidation of pyrite is modeled using the local equilibrium approach, whereas decomposition of organic matter, with the adoption of kinetic approach. The system is buffered by dissolution of aluminum and iron oxides. The modeling process is a two-step procedure. First, the processes are modeled in the one-dimensional (1D) column using PHREEQC code. Subsequently, the calibrated and verified data were copied and used in two-dimensional (2D) PHAST model. Prior to the performance of reactive transport modeling operations with PHAST, a reliable flow model was executed. Finally, predictions are made for the distribution of water chemistry for the year 2008. Model predicts that sulfate derived from the ongoing pyrite oxidation is reduced by the dissolved organic carbon at the higher depth and forms pyrite by the reaction with iron. The results of this study highlight the importance of understanding the interplay between the transport and chemical reactions that occur during the input of nitrate to the aquifer. Reactive transport modeling incorporating the use of a newly developed code PHAST have proved to be a powerful tool for analyzing and quantifying such interactions.  相似文献   
210.
现被广泛应用的测定高演化碳酸盐岩成熟度指标的多项有机岩石学评价方法,各有其不同的局限性,应用效果并不理想。研究发现,可利用芳烃演化新参数来代替其它失效的分子参数来评价碳酸盐岩有机质。芳烃因其结构、组成的特殊性和稳定性,在高演化阶段与油气生成及煤源岩成熟度有着良好的相关性,具有成为高演化碳酸盐岩成熟度指标的基础。从生产实践的角度看,芳烃演化参数有特殊适用性及选取的可行性。  相似文献   
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