全文获取类型
收费全文 | 816篇 |
免费 | 78篇 |
国内免费 | 91篇 |
专业分类
测绘学 | 60篇 |
大气科学 | 15篇 |
地球物理 | 137篇 |
地质学 | 315篇 |
海洋学 | 320篇 |
天文学 | 4篇 |
综合类 | 122篇 |
自然地理 | 12篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2015年 | 9篇 |
2014年 | 1篇 |
2013年 | 8篇 |
2012年 | 2篇 |
2011年 | 89篇 |
2010年 | 53篇 |
2009年 | 113篇 |
2008年 | 27篇 |
2007年 | 22篇 |
2006年 | 39篇 |
2005年 | 41篇 |
2004年 | 129篇 |
2003年 | 73篇 |
2002年 | 65篇 |
2001年 | 25篇 |
2000年 | 16篇 |
1999年 | 39篇 |
1998年 | 47篇 |
1997年 | 39篇 |
1996年 | 16篇 |
1995年 | 33篇 |
1994年 | 19篇 |
1993年 | 22篇 |
1992年 | 17篇 |
1991年 | 12篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1966年 | 2篇 |
1960年 | 1篇 |
排序方式: 共有985条查询结果,搜索用时 15 毫秒
221.
222.
WANG Bin QIU Jianhui ZHAO Dong YANG Xi DAI Shuai.College of Construction Engineering Jilin University Changchun China .Design Institute of Jilin Architectural Civil Engineering Institute Changchun China 《东北亚地学研究》2009,12(1):28-31
The finite element method was used for analysis of raft foundation design in high-rise building. Compared with other conventional methods, this method is more adapted to the practical condition since both superstructure stiffness and soil conditions were considered in calculation. The calculation results by example show that the base reaction is more uniform and the maximum reaction decreases obviously. Accordingly, the raft foundation design is more economic without any loss of security for high-rise building. 相似文献
223.
ZHAN Jiajia XU Huiwen CAI Hongliang .College of Construction Engineering Jilin University Changchun China .China Water Northeastern Investigation Design Research Co.Ltd Changchun China 《东北亚地学研究》2009,12(1):32-35
Drilling fluid additives has a major impact on rheology behavior and other performances of the drilling fluid. The key to low temperature drilling fluids is choosing antifreeze and polymer agent which have a strong ability in resisting low temperature. On the basis of determining glycol as antifreeze agent, the low-temperatureperformance and capacities of anti-collapse of regular validity mud agents have been studied, the mechanism of anti-caving of the partially hydrolyzed polyacrylamide (PHPA), polypropylene potassium (KPA) and PAC-141 polymer additives have been also analyzed. A pilot study of compatibility between ethylene glycol and the polymers has educed that the polymers, ethylene glycol and inorganic salt are compatible, and they can significantly reduce the freezing point of drilling fluid. Anti-collapse ability of the drilling mud is the results of synergistic action among the agents. 相似文献
224.
MA Ruijie LI Xin. College of Mathematics Jilin University Changchun China . College of Construction Engineering China 《东北亚地学研究》2009,(3):164-167
The underground water quality model with non-linear inversion problem is ill-posed, and boils down to solving the minimum of nonlinear function. Genetic algorithms are adopted in a number of individuals of groups by iterative search to find the optimal solution of the problem, the encoding strings as its operational objective, and achieving the iterative calculations by the genetic operators. It is an effective method of inverse problems of groundwater, with incomparable advantages and practical significances. 相似文献
225.
MENG Fanqi LI Guangjie College of Construction Engineering Jilin University Changchun China 《东北亚地学研究》2009,12(2):105-108
The Chedaren ravine belongs to high-prone areas of debris flow in Jilin Province, which threaten the local people' s life and security seriously. The authors used the residual correction theory to amend the GM ( 1, 1 ) model and forecast annual precipitation in disaster year of the Chedaren ravine ; it provides scientific foundation for early warning of debris flow disaster in the rainy season based on weather forecast. The prediction resuits show that annual precipitation is 724.7 mm in 2009 ; the region will probably occur large-scale debris flow during the rainy season. 相似文献
226.
CAO Pinlu ZHANG Jincheng WU Xia HUANG Jinyun Institute of Drilling Engineering Technology Zhongyuan Petroleum Exploration Bureau Puyang Henan China 《东北亚地学研究》2009,(4):204-209,214
In recent years, air-foam combining the advantages of both liquid and air drilling has been utilized as a drilling medium. Air-foam drilling has proved its efficiency in numerous situations where serious problems were encountered, such as in fractured formations and depleted or high permeable zones. However, the major disadvantage of air-foam drilling system is that the foam can only be used once, so that an extremely large pit is required to contain the foam to allow sufficient room for cuttings and for the foam to dissipate. Moreover, it needs enormous volume prepared, consuming abundance of water and ingredient additives, which results in the high cost of foam drilling. The recycling foam fluid by using foam breaking technology is the only effective method to solve these problems associated with the known foam drilling. Various types of equipment and technique have been employed to suppress foam formation in biological and process equipment in foam drilling. The study described various methods of foam breaking technology, and the trend of the foam breaking technology for foam drilling is discussed. 相似文献
227.
Jihua HU Yanjun ZHANG Danyan DU Gang WU Ziwang YU Chen WANG Fuquan NI. College of Construction Engineering Jilin University Changchun China. College of Environment Resources China. College of Information Engineering Sichuan Agricultural University Ya 'an Sichuan China 《东北亚地学研究》2008,11(3):182-187
Energy utilization in the aquifers is a new technology closely related to development of heat pump technique. It is significant for the flow distribution to be predicted in the aquifer surrounding the Groundwater Source Heat Pump System (GSHPS). The authors presented a new concept of "flow transfixion" by analyzing general features of aquifers, and then discussed interaction of the flow transfixion with the beat transfixion, which has practical significance to projects. A numerical model of groundwater flow was established based on the basic tenets of water-heat transferring in the aquifer. On this basis the flow field and the temperature field of GSHPS for a site in Shenyang City were numerically simulated. The basis of the flow transfixion was obtained; it was discussed for the influence of the flow transfixion on the heat transfixion. To a certain extent, the study offers some reference for the projects' design of GSHP in the studied area. 相似文献
228.
Caikun GAO Huakun DU Jingtian TANG Kangxiu WU Chang'an XIAO Shiping WANG 《东北亚地学研究》2008,11(3):191-196
Integrated geophysical interpretation is a method of combinating different geophysics prospecting methods based on different physical properties of accumulation. As different geophysical methods own different interpretations and varying detection accuracies, the key issue becomes how to integrate the results of several geophysical methods to corrently carry out a comprehensive explanation. Based on different geophysical results, the authors proposed an integrated geophysical explanation method and successfully applied it in practical engineering problems. 相似文献
229.
Chengdong QI Guohua QIAO Hongchen DONG Dayei LUI Xing ZHANG Deli YU .Regional Survey of Geology & Mineral Resources Jilin Province Changchun China.College of Material Science Engineering Jilin University Changchun China 《东北亚地学研究》2008,11(4):214-217
LA-ICP MS zircon U-Pb dating results of granites from Sawuer Mountains in North Xinjiang, NW China, are reported based on 1:50 000 regional geologic surveys. Zircon U-Pb dating shows that the granitoids have magmatic crystallization age of 320 ± 2 Ma. In addition, zircons with ages of 341 -358 Ma could be subdivided into two groups, i. e. , Group 1 with a weighted mean age of 342 ± 3 Ma and Group 2 with a weighted mean age of 354 ± 2 Ma. The petrology and geochemistry of granitoids from Sawuer Mountains suggest their mixed origin. The granite from Sawuer Mountains occurred in an extensional setting, most probably related to post-orogenic processes during the closure of the Peo-Asian Ocean ; namely, represent the tectonic setting shifted from compress to post-collisional setting. 相似文献
230.
Dajun ZHAO Guosheng JIANG Youhong SUN Junhua ZHENG Zhuwen WANG .Faculty of Engineering China University of Geosciences Wuhan China.College of Construction Engineering Jilin University Changchun China.College of Geoexploration Science Technology China 《东北亚地学研究》2008,11(4):228-231
A high efficiency method is very important in geological survey for a new city in China. Geophysical parameters are Measured While Drilling (MWD), and these parameters are processed and explained on the ground, so the method can replace conventional engineering geological exploration for drilling rock sample. According petroleum engineering MWD, using the different characters of different rock absorbs γ radial, with the method of storing data in hole and explaining data on the ground, engineering geological exploration formation density MWD is researched. The MWD works stabilized, and the performance is good with precise data. 相似文献