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81.
82.
The tropical Pacific has begun to experience a new type of El Nio, which has occurred particularly frequently during the last decade, referred to as the central Pacific(CP) El Nio. Various coupled models with different degrees of complexity have been used to make real-time El Nio predictions, but high uncertainty still exists in their forecasts. It remains unknown as to how much of this uncertainty is specifically related to the new CP-type El Nio and how much is common to both this type and the conventional Eastern Pacific(EP)-type El Nio. In this study, the deterministic performance of an El Nio–Southern Oscillation(ENSO) ensemble prediction system is examined for the two types of El Nio. Ensemble hindcasts are run for the nine EP El Nio events and twelve CP El Nio events that have occurred since 1950. The results show that(1) the skill scores for the EP events are significantly better than those for the CP events, at all lead times;(2) the systematic forecast biases come mostly from the prediction of the CP events; and(3) the systematic error is characterized by an overly warm eastern Pacific during the spring season, indicating a stronger spring prediction barrier for the CP El Nio. Further improvements to coupled atmosphere–ocean models in terms of CP El Nio prediction should be recognized as a key and high-priority task for the climate prediction community. 相似文献
83.
84.
矿产勘查模型的建立原则——以个旧锡多金属成矿区为例 总被引:1,自引:0,他引:1
在成矿规律研究和系统分析基础上建立矿产勘查模型时,应考虑不同层次勘查对象的查明程度的差别。根据“方法—目标—成果”构式的不同划分勘查类型,根据矿化类型及矿床产出位置的不同划分亚类型。建模过程中要进行成矿标志分析和方案对比。 相似文献
85.
�˼�ϵͳ����GEO���Ǽ��η����� 总被引:3,自引:2,他引:1
????GEO??????η???????????????????????????????μ?GEO??????η??????????????????????????????λ?ò??????????????????????????????????????????????????????????ζ????3???????μ?GEO??????η?????????????????????÷????????????????GEO??????η??????????????????????????????μ????????????μ?λ?÷???X??Y???н????????????????????С????PDOP???仯???仯??????????X??Y??????????????????????Z???????????????????Z??????????????????? 相似文献
86.
资源三号影像对地目标定位的系统误差补偿 总被引:1,自引:0,他引:1
针对资源三号影像无地面控制的对地目标定位研究的不足,该文从资源三号成像传感器的成像机理出发,通过对焦平面坐标系内CCD探元系统误差的分析,提出一种基于CCD探元系统误差补偿的资源三号影像对地目标定位方法。试验结果表明,在无需对资源三号成像传感器进行在轨几何定标的情况下,该方法可以有效消除定位结果中的系统误差,提高资源三号影像无地面控制对地目标定位精度。 相似文献
87.
区域地理与系统地理二元论的演变及其透析 总被引:3,自引:1,他引:2
地理学是一门追求普适性的学科,还是强调其独特性,这个"普适"与"例外"的问题曾引起地理学史上最大的方法论争论。它反映出系统地理学与区域地理学的二元论。系统地理学家强调地理学追求一般法则,区域学派则认为研究独特的区域是地理学的核心。这种二元论争论在古希腊时代就初见端倪,"舍费尔—哈特向之争"则使其达到顶点。对争论的历史根源和发展演变的分析表明:虽然两个学派的代表人物哈特向和舍费尔都至少在形式上反对只强调系统和区域中的一个而忽视另一个的做法,但是他们的兴趣、价值观导致的偏好和地理学史观的重大分歧,使他们最终对区域地理和系统地理的倾向不一样。20世纪80年代的"哈特—格里奇之争"只是这种二元论的一个余波。其后,多元主义方法论的兴起使得这种二元论争论逐渐淡出人们的视野,但后现代地理学聚焦于"批判的区域研究",实质上仍是这种争论在新时代的变种。中国地理学界缺乏此种争论,原因可能在于"实用主义"的学术导向、学术环境、学术评价体制、折中调和的理论构建方式等。这不利于中国地理学自立于世界学术之林。 相似文献
88.
89.
The present study describes an analysis of Asian summer monsoon forecasts with an operational general circulation model (GCM)
of the European Centre for Medium Range Weather Forecasts (ECMWF), U.K. An attempt is made to examine the influence of improved
treatment of physical processes on the reduction of systematic errors. As some of the major changes in the parameterization
of physical processes, such as modification to the infrared radiation scheme, deep cumulus convection scheme, introduction
of the shallow convection scheme etc., were introduced during 1985–88, a thorough systematic error analysis of the ECMWF monsoon
forecasts is carried out for a period prior to the incorporation of such changes i.e. summer monsoon season (June–August)
of 1984, and for the corresponding period after relevant changes were implemented (summer monsoon season of 1988).
Monsoon forecasts of the ECMWF demonstrate an increasing trend of forecast skill after the implementation of the major changes
in parameterizations of radiation, convection and land-surface processes. Further, the upper level flow is found to be more
predictable than that of the lower level and wind forecasts display a better skill than temperature. Apart from this, a notable
increase in the magnitudes of persistence error statistics indicates that the monsoon circulation in the analysed fields became
more intense with the introduction of changes in the operational forecasting system.
Although, considerable reduction in systematic errors of the Asian summer monsoon forecasts is observed (up to day-5) with
the introduction of major changes in the treatment of physical processes, the nature of errors remain unchanged (by day-10).
The forecast errors of temperature and moisture in the middle troposphere are also reduced due to the changes in treatment
of longwave radiation. Moreover, the introduction of shallow convection helped it further by enhancing the vertical transports
of heat and moisture from the lower troposphere. Though, the hydrological cycle in the operational forecasts appears to have
enhanced with the major modifications and improvements to the physical parameterization schemes, certain regional peculiarities
have developed in the simulated rainfall distribution over the monsoon region. Hence, this study suggests further attempts
to improve the formulations of physical processes for further reduction of systematic forecast errors. 相似文献
90.
山西省热矿水形成机制分析 总被引:1,自引:0,他引:1
本文以系统理论为指导,在深入研究地质北景的基础上,通过研究热矿水的含水介质,水动力场,水化学物和温度场的特征,划分了热矿水系统,探讨了热矿水的起源及形成机制,将山西热矿水的形成归纳为异常增温型和正常增温型两种基本模式,异常增温型又根据地质结构的不同,地下水径流条件的差异,列举了三种典型模式,最后指出了寻找热矿水的方向,开发利用热矿资源应注意的问题。 相似文献