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   1212篇
  免费   115篇
  国内免费   75篇
测绘学   73篇
大气科学   66篇
地球物理   281篇
地质学   409篇
海洋学   152篇
天文学   113篇
综合类   274篇
自然地理   34篇
  2023年   32篇
  2022年   18篇
  2021年   33篇
  2020年   51篇
  2019年   139篇
  2018年   10篇
  2017年   3篇
  2016年   7篇
  2015年   5篇
  2014年   12篇
  2013年   8篇
  2012年   2篇
  2011年   3篇
  2010年   4篇
  2009年   11篇
  2008年   13篇
  2007年   31篇
  2006年   34篇
  2005年   35篇
  2004年   94篇
  2003年   70篇
  2002年   84篇
  2001年   87篇
  2000年   273篇
  1999年   106篇
  1998年   19篇
  1997年   18篇
  1996年   48篇
  1995年   30篇
  1994年   39篇
  1993年   7篇
  1992年   8篇
  1991年   6篇
  1990年   11篇
  1989年   6篇
  1988年   7篇
  1987年   9篇
  1986年   1篇
  1985年   3篇
  1984年   7篇
  1983年   4篇
  1982年   2篇
  1981年   2篇
  1979年   1篇
  1975年   1篇
  1974年   1篇
  1963年   3篇
  1961年   1篇
  1957年   2篇
  1954年   1篇
排序方式: 共有1402条查询结果,搜索用时 15 毫秒
31.
LI  Wen-long 《中国海洋工程》2003,17(4):541-550
The floating oil storage system has been proposed as a new facility for Strategic Petroleum Reserve (SPR) in China. Mooring is one of the key technologies to ensure the safety, reliability, and performance of the oil storage system. This paper describes the concept, analysis, design and reliability of the mooring system. For mooring system design of these oil vessels, analysis is essential of the behavior of the vessel in connection with mooring facilities of nonlinear resilience. A nonlinear mathematical model for analyzing a moored vessel is established and solved. Some results of numerical simulations are presented. Assessment of the safety regarding the mooring system in terms of failure probability is carried out. Another simulation model for calculating the failure probability of the mooring system is proposed. The design parameters that have an influence on the characteristics of the failure probability have been identified. The simulation results show that the mooring system has an annual reliab  相似文献   
32.
Second-Order Wave Diffraction Around 3-D Bodies by A Time-Domain Method   总被引:1,自引:1,他引:1  
BAI  Wei 《中国海洋工程》2001,(1):73-84
A time-domain method is applied to simulate nonlinear wave diffraction around a surface piercing 3-D arbitrary body. The method involves the application of Taylor series expansions and the use of perturbation procedure to establish the corresponding boundary value problems with respect to a time-independent fluid domain. A boundary element method based on B-spline expansion is used to calculate the wave field at each time step, and the free surface boundary condition is satisfied to the second order of wave steepness by a numerical integration in time. An artificial damping layer is adopted on the free surface for the removal of wave reflection from the outer boundary. As an illustration, the method is used to compute the second-order wave forces and run-up on a surface-piercing circular cylinder. The present method is found to be accurate, computationally efficient, and numerically stable.  相似文献   
33.
1Introduction TheIndianCentralWater (ICW) ,formedandsubductedintheSubtropicalConvergenceintheSouthIndianOcean ,occupiesasignificantportionofthethermoclineintheIndianOcean[1,2 ]  (Fig .1 ) .TheSubantarcticModeWater(SAMW)isformedinthe 2 6.5-2 7.1σθrangenorthoftheSub antarcticFront—thesouthernboundaryofthesubtropicalgyres[3]  .InthesoutheastIndianO cean ,theSAMWisthethickest,ventilatedasathicklayerofhighoxygenextendingtothetropicalIndianOcean[4 ,5 ]  . Watermasstransformation…  相似文献   
34.
Non-Simultaneous Failure of Ice in Front of Multi-Leg Structures   总被引:4,自引:1,他引:4  
SHI  Qingzeng 《中国海洋工程》2002,16(2):183-192
Because the multi-leg jacket structure is the major type of offshore structures in the Bohai Sea, the study of non-si-multaneous failure of i鏴 on multi-leg structures is important. However, the non-simultaneous failure has not been consid-ered in engineering design until now, obviously resulting in costly design and notable waste. To resolve this problem, this paper, by means of analysis of experimental data, calculates the coefficient of the non-simultaneous failure for the double-pile structure, the square four-leg structure, the single-line multi-pile structure, and the conical structure, respectively, and provides some reference criteria for engineering design.  相似文献   
35.
1.Lecithochiriumfukenensissp.nov.(Fig.1)(Basedon6wholemounts)ThisspiceswascollectedinthestomachofTrichiurushaumelafromXiamenandNan'ao.Bodydividedintosomaandecsoma.Soma1,31~3.48×0.426~1.05(2.69×0.737),ecsoma0.22~0.80(0.448)longwhenprotruded,usuallycomple…  相似文献   
36.
LI  Yanbao 《中国海洋工程》2002,16(2):211-218
In this paper, the theoretical analysis and experimental studies are employed to investigate the reflection characteris-tics of partial standing waves caused by wave overtopping and sloping top of structures. Based on the principle of conser-vation of wave energy flux, the third-order Stokes wave theory is used to formulate the reflection coefficient at wave overtopping; the calculation results are regressed into an applied expression. A series of experiments of wave reflection for a vertical-wall structure with chamfered and overhanging upper sections are carried out to investigate the influence of top slope on wave reflection. The regularity of variation of wave reflection in this case is analysed based on the experimental results.  相似文献   
37.
LU  Peidong 《中国海洋工程》2002,16(2):219-226
The phase one project of the twin jetties at the Tao-er Estuary yields no effect on the flow, and there is a large area of deposition. A numerical model is employed to simulate the flow field, and the scouring and silting in the channel be-tween the two jetties are analyzed. The results show that the effective tidal flux between the two jetties is reduced due to the notch located at the heel of the east jetty, and the effect of contraction-flush is not obvious. As for the regulation of this kind of estuary under the tide action, the capability of tidal flux should be fully used.  相似文献   
38.
In this paper, the characteristics of different forms of mild slope equations for non-linear wave are analyzed, and new non-linear theoretic models for wave propagation are presented, with non-linear terms added to the mild slope equations for non-stationary linear waves and dissipative effects considered. Numerical simulation models are developed of non-linear wave propagation for waters of mildly varying topography with complicated boundary, and the effects are studied of different non-linear corrections on calculation results of extended mild slope equations. Systematical numerical simulation tests show that the present models can effectively reflect non-linear effects.  相似文献   
39.
随着全球经济一体化趋势的进一步发展,21世纪的全球商务活动和经济活动必然随着生产分工的逐步细分而逐步淡化国家的概念。国家与国家之间的经济关系表现为一种相互依赖但又有其独立性的特点。世界级的跨国公司通过其在各个国家的分公司或分支组织,对这种商务活动依据其本身的利益,依据市场进行宏观的组织管理。  相似文献   
40.
中国石油工程建设(集团)公司(中文简称:中国石油工程公司,英文缩写:CPECC)是中国最早进入国际工程承包市场的公司之一。1980年经国务院批准,开始经营对外工程承包和劳务合作业务,现已发展成为中国石油天然气集团公司在国际油气工程建设领域最具有代表性的公司,是中国最大的国际工程总承包企业之一。  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