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   79篇
  免费   5篇
  国内免费   28篇
大气科学   10篇
地球物理   9篇
地质学   75篇
海洋学   10篇
天文学   1篇
综合类   5篇
自然地理   2篇
  2014年   1篇
  2013年   2篇
  2011年   1篇
  2010年   5篇
  2009年   6篇
  2008年   11篇
  2007年   7篇
  2006年   9篇
  2005年   8篇
  2004年   13篇
  2003年   7篇
  2002年   2篇
  2001年   11篇
  2000年   5篇
  1999年   2篇
  1998年   6篇
  1997年   1篇
  1996年   1篇
  1994年   2篇
  1993年   1篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1960年   2篇
  1959年   2篇
排序方式: 共有112条查询结果,搜索用时 15 毫秒
61.
Leping coal (including barkinite-rich coal) is a unique kind of coal,which is widely distrbuted in the Late Permian Longan Formation,South China,In this paper,ROck-Eval,Py-GC and simulation experiment via an open-system were used to study the hydrocarbon-generating potential,hydrocarbon composition.and hydrocarbon-generating model of barkiniterich coals from the shuicheng coal field of Guizhou Province,Southwest China.The results show that barkinite-rich coals have high hydrocarbon-generating potential,with S1 S2 being 211-311mg/g,and can produce large amounts of hydrocorbon at the high-maturity stage,mostly within the temperature range of 420-450℃(corresponding to VR0 1.1-1.5%);barkinite-rich coal is one of the better oil sources and light hydrocarbon and wet gas are the major hydrocarbon components,which account for 45% and 33% of the total hydrocarbons.respectively.These characteristics are of importance for exploring oil and gas resources in the Late permian Longtan Formation coals,southwest China.  相似文献   
62.
德国《商报》2009年8月28日发表文章说,美国地质学家的实验表明,在地表以下50多千米处可能产生碳氢化合物,也就是相当于化石燃料的化合物。  相似文献   
63.
The Jurassic coals of the Junggar and Turpan-Hami basins, Xinjiang, China, are characterized by abundant vitrinite. Microscopic analysis of Junggar coal samples indicates that they contain desmocollinite and hydrogen-rich vitrinite with a low reflectivity. The hydrocarbon-generating potential of various macerais follows the decreasing order of exinite > vitrinite > inertinite. However, desmocollinite is a principal maceral for hydrocarbon generation in this area because the content of vitrinite is higher than that of exinite. Data from simulating experiments and infrared spectra show that the hydrocarbon-generating process occurred primarily at the lower-mature stage in the Middle-Lower Jurassic coal measures. Generally, crude oil from the Qigu oilfield has a close similarity in hopanoid distribution to the vitrinite and exinite from the Jurassic strata with C23-C32 pentacyclic triterpanes and γ-lupane being present. The distribution of steranes is also similar. C29-sitostane is dominant and Q27 ergostane is subordinate. Only a trace amount of cholestane is present. All this suggests that the crude oil from the Qigu oilfield was derived from Jurassic coal measures.  相似文献   
64.
Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into three types as the Naxi, Tahe and Renqiu ones, increasing successively in the development degree of karstificated pores and fissures and the connection degree of independent reservoirs. In these reservoirs, the unity in the fluid feature, pressure and oil-gaswater interface also increases successively from the Naxi to the Renqiu type. The main body of Ordovician reservoirs of the Tahe Oilfield in the Tarim Basin is a network pool rather than a stratified, massive, stratigraphically-unconformed or weathering-crust one. The fluid nature of oil, gas and water, the interface positions and the pressures, as well as the dynamic conditions of fluids within the reservoirs during the production are all different from those in stratified or massive oil and gas reservoirs. Carbonates in the Akekule uplift and the Tahe Oilfield are assemblages of various types of reservoirs, which have an overall oH-bearing potential and obvious uneven distribution. Testing and producing tests are the major means to evaluate this type of reservoirs and acid fracturing improvement is a key link in petroleum exploration and development.  相似文献   
65.
成岩伊利石K—Ar年龄分析及其意义   总被引:6,自引:0,他引:6  
烃源岩何时达到最高温度以及其经历加热时与成油构造的时间关系,一直是油气勘探研究中的关系问题。成岩作利石的K-Ar年龄可以用来确定碳氢化合物的形成时间,但由于无法将成岩伊利石从沉积岩中单独分离出来,因工源岩达到最高温度的时间一直不能确定,伊利石K-Ar年龄分析(IAA)方法的建立,使成岩伊利石年龄的获得成为可能。利用该方法对塔里木盆地某地区2772m处的奥陶系烃源层达到最高温度的时代进行了分析,结果表明,该地层是在上志留纪(408Ma)达到最高温度的。  相似文献   
66.
67.
《地理教学》2013,(21):64-64,63
怪异行星的样本 土卫六看起来的确很像地球,但它非常寒冷,昏暗。那里的石头由水冰组成,湖水由碳氢化合物组成。土卫六的表面温度为零下180℃,活脱就是“太空冰箱”,人们至今没有在那里找到可以得到证实的生命迹象也便不足为奇了。  相似文献   
68.
A total of 11 PM2.5 samples were collected from October 2003 to October 2004 at 8 sampling sites in Beijing city. The PM2.5 concentrations are all above the PM2.5 pollution standard (65 μg m^-3) established by Environmental Protection Agency, USA (USEPA) in 1997 except for the Ming Tombs site. PM2.5 concentrations in winter are much higher than in summer. The 16 Polycyclic aromatic hydrocarbons (PAHs) listed as priority pollutants by USEPA in PM2.5 were completely identified and quantified by high performance liquid chromatography (HPLC) with variable wavelength detector (VWD) and fluorescence detector (FLD) employed. The PM2.5 concentrations indicate that the pollution situation is still serious in Beijing. The sum of 16 PAHs concentrations ranged from 22.17 to 5366 ng m^-3. The concentrations of the heavier molecular weight PAHs have a different pollution trend from the lower PAHs. Seasonal variations were mainly attributed to the difference in coal combustion emission and meteorological conditions. The source apportionment analysis suggests that PAHs from PM2.5 in Beijing city mainly come from coal combustion and vehicle exhaust emission. New measures about restricting coal combustion and vehicle exhaust must be established as soon as possible to improve the air pollution situation in Beijing city.  相似文献   
69.
近十年来,石油类碳氢化合物,尤其是油溢带来的污染引起了广泛的关注。油溢会影响到自然菌落及其受污染菌落点的物理和化学性质。生物降解碳氢化合物是一种主要的除去油类泄漏污染源的方法。1997年1月2日,一艘名为纳霍德卡(Nakhodka)的俄罗斯油轮在日本海发生重油溢漏污染事故。纳霍德卡号油溢事件导致粘稠的流体污染了海岸,影响了周围的生态环境。本文详述了碳氢化合物降解细菌(假单胞菌种)的褪变,确定了九年后来自于纳霍德卡号油溢污染海岸的有机化合物。经过十年的生物修复,纳霍德卡溢油变硬.XRD分析结果中与石墨和方解石有关的0.422,  相似文献   
70.
Pollution of petroleum hydrocarbons, in particular oil spills, has attracted much attention in the past and recent decades. Oil spills influence natural microbial community, and physical and chemical properties of the affected sites. The biodegradation of hydrocarbons by microorganisms is one of the primary ways by which oil spill is eliminated from contaminated sites. One such spill was that of the Russian tanker the Nakhodka that spilled heavy oil into the Sea of Japan on January 2, 1997. The impact of the Nakhodka oil spill resulted in a viscous sticky fluid fouling the shores and affected natural ecosystems. This paper describes the weathering of hydrocarbon-degrading bacteria (genus Pseudomonas) and crystallized organic compounds from the Nakhodka oil spill-polluted seashores after nine years. The Nakhodka oil has hardened and formed crust of crystalline paraffin wax as shown by XRD analysis (0.422, 0.377, and 0.250 nm d-spacing) in association with graphite and calcite after 9 years of bioremediation. Anaerobic reverse side of the oil crust contained numerous coccus typed bacteria associated with halite. The finding of hydrocarbon-degrading bacteria and paraffin wax in the oil crust may have a significant effect on the weathering processes of the Nakhodka oil spill during the 9- year bioremediation.  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