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961.
962.
The Indian subcontinent has the largest semi-arid tropical (SAT) area among developing nations. The State of Andhra Pradesh
falls under the SAT region in India and is mostly covered by compact and hard rocks, characterized by seasonal rainfall of
a highly fluctuating nature, in both space and time. As a consequence of the green revolution and an increase in industrial
activity, there has been an increase in the utilization of groundwater resources during the last two decades in Andhra Pradesh.
The development has also caused a number of problems, such as water table decline, decrease in well yields and seawater intrusion.
Although major irrigation projects have contributed to improved agricultural production, the associated problems of waterlogging,
salinization and loss of valuable bioresources have led to the gradual degradation of the land, affecting agricultural productivity.
Surface water and groundwater have also been polluted in several parts of the State because of untreated discharge of effluents
from the industries into nearby streams or open lands. A brief account of the overall scenario of the hydrogeological framework
and geo-environmental effects on the groundwater regime in Andhra Pradesh is presented. Possible management practices and
conservation methods are suggested.
Received: 9 August 1999 · Accepted: 10 July 2000 相似文献
963.
四川省德阳市地下水水质模糊数学综合评价 总被引:1,自引:0,他引:1
首先介绍模糊数学在国内水质评价中的应用及其优势,分析其在地下水水质评价中的原理和方法.然后以德阳市20组水样分析资料为基础.应用模糊数学原理对其地下水质进行模糊综合评价.结果表明,区内地下水水质无Ⅰ级,Ⅱ级占15%,Ⅲ级占45%,Ⅳ级占10%,Ⅴ级占30%.工业排放、生活垃圾和原乍铁锰超标是部分地区水质污染或超标的主要... 相似文献
964.
地下水模型MODFLOW和GIS在华北平原地下水资源评价中的应用 总被引:2,自引:0,他引:2
从MODFLOW源程序的角度出发,根据地下水模型计算需要的输入输出数据格式和我国GIS类数据以MAPGIS为主的特点,建立了二者之间的集成关系,并将其应用于华北平原地下水资源评价中。根据华北平原特定的水文地质条件,建立了适合本区的三维非稳定流地下水模型,结合2003年12月的实际流场以及随时间变化的动态观测资料对模型的渗透系数、给水度和释水系数等参数进行了校正。同时进行了水均衡分析,结果表明华北平原地下水在2002年1月至2003年12月总补给量为493.74×108m3,总排泄量为565.30×108m3,均衡差为-71.56×108m3,为负均衡。集成了该地下水模型的信息系统,可以通过更新源汇项数据库资料而对地下水资源进行实时评价,为华北平原水资源可持续利用和管理提供依据。 相似文献
965.
Z. J. Kabala A. Hunt 《Stochastic Environmental Research and Risk Assessment (SERRA)》1993,7(4):255-268
The mean value of a density of a cloud of points described by a generalized Liouville equation associated with a convection dispersion equation governing adsorbing solute transport yields a joint concentration probability density. The general technique can be applied for either linear or nonlinear adsorption; here the application is restricted to linear adsorption in one-dimensional transport. The equation generated for the joint concentration probability density is in the general form of a Fokker-Planck equation, but with a suitable coordinate transformation, it is possible to represent it as a diffusion equation with variable coefficients. 相似文献
966.
Tai Sasaki Naro Hashimoto Takayuki Nakato Tomonari Shiraishi Kazuaki Yajima Tomoyuki Hishiya 《Engineering Geology》1998,49(3-4):337-343
As a preliminary step for predicting groundwater flow in a plateau 30–50 m above sea level, a model for three-dimensional analysis of groundwater flow was formulated and its validity was verified. The plateau consists of Neogene sedimentary rocks and a Quaternary deposit. Most of the groundwater originates in precipitation, with the groundwater table lying in the Quaternary deposit. Steady-state analysis was conducted by using the finite element method. The results of pore-water pressure measurement and water examination were useful in verifying the validity of the model. In constructing the model, reducing the hydraulic conductivity according to the depth on the basis of the results of the actual measurement was important. 相似文献
967.
A comparative analysis of enzyme leach and mobile metal ion selective extractions; case studies from glaciated terrain, northern Ontario 总被引:1,自引:0,他引:1
A. F. Bajc 《Journal of Geochemical Exploration》1998,61(1-3)
The enzyme leach and MMI (mobile metal ion) selective digestions are rapidly gaining popularity in the exploration community because of their successful track record in non-glaciated, arid and tropical climatic regions. Few successful case studies from high-latitude, temperate regions have been published to date. Also lacking is a comprehensive discussion of the constraints and limitations of these geochemical methods and how they affect the successful interpretation of selective-leach survey results in glaciated regions. This paper evaluates each method using specific examples from four case studies undertaken in the glaciated region of northern Ontario. The case studies clearly demonstrate that both the MMI and enzyme leach selective digestions provide the explorationist with useful information, which, when used in conjunction with other exploration tools, can assist with the identification of potential diamond drill targets. Notwithstanding this, the techniques do not appear to work well as ‘stand alone' methods. The importance of following strict sampling protocols and obtaining high-quality observational information on the sampling site and media collected cannot be overstressed. It is only by filtering out the many variables that arise in any sampling program that a sound interpretation of the data can be made. The case studies have drawn attention to some of the apparent shortfalls of the techniques. Of these, issues such as the ability to reproduce survey results from year to year and the recognition of anomalous element associations which specifically target blind mineralisation are probably those which require significant follow-up work. Clearly, additional case studies are required from the glaciated regions of the world to assist with the optimisation of geochemical response of MMI and enzyme leach selective extractions. The mechanisms responsible for the formation of surface geochemical anomalies over deeply buried mineralisation are not well understood. The observed patterns of geochemical response in surface soils and both shallow and deep ground waters over concealed mineralisation should assist with the development of new dispersion models. 相似文献
968.
The impact of human activities in the Malia coastal area (Crete) on groundwater quality 总被引:1,自引:0,他引:1
N. J. Lambrakis 《Environmental Geology》1998,36(1-2):87-92
The evaluation of the long-term effects of seawater intrusion into the aquifers due to negative water balance and nitrate
pollution of drinking-water quality due to human activities requires detailed knowledge of both the transport of the chemical
constituents and the geochemical processes within aquifers. Hydrogeological and hydrochemical studies in the unconfined aquifer
of Malia have provided the necessary data to define the areas at increased risk from these phenomena. The solution of the
second Fick's low under given boundary conditions gave an estimate of the propagation of groundwater pollution by NO3
–. Additionally, in order to simulate the ion concentration changes during a period, for example a period of positive water
balance or refreshening, groundwater transport and cation exchange reactions were modelled using the code PHREEQM.
Received: 25 July 1997 · Accepted: 4 November 1997 相似文献
969.
Delineation of groundwater protection zones based on tracer tests and transport modeling in alluvial sediments 总被引:1,自引:0,他引:1
Regulations aiming to protect exploitable groundwater resources were edicted in Belgium a few years ago. Therefore, prevention
and protection zones are defined by law and must be determined practically around each pumping well or spring, based on local
hydrogeological conditions. The determination of hydrodynamic and hydrodispersive parameters, characterizing the local flow
and transport properties of the aquifer, requires pumping and tracing tests. The interpretation of these field experiments,
considering the heterogeneity of the geological layers, is performed through the use of numerical FEM simulations of the groundwater
flow and pollutant transport conditions in a deterministic framework. After calibration of the model on experimental measurements,
multiple simulations with contaminant injections at various points of the modeled domain allow the determination of the transfer
time of the pollutant in the studied aquifer whilst taking the updated heterogeneity into account. On the basis of the computed
transfer times in the saturated zone, the various prevention and protection areas can be assessed based on provisions of the
law.
Received: 27 June 1997 · Accepted: 29 July 1997 相似文献
970.
This paper presents karst water protection measures being introduced in the Dinarides of Croatia. The spring sites for the
water supply of the town of Rijeka, for its 200 000 inhabitants and the largest harbor of the northeastern side of the Adriatic
Sea, have been used as a pilot research area. The European research project was used, and protection of water was generally
divided into three phases. A categorization of springs has been made, and five basic protection zones have been distinguished.
The rules of behavior in protected zones have been outlined. For the first time, the term water-supply "reserve" has been introduced, referring to the parts of the mountainous region where karst groundwater is recharged.
Received: 26 March 1997 · Accepted: 22 July 1997 相似文献