全文获取类型
收费全文 | 3177篇 |
免费 | 468篇 |
国内免费 | 657篇 |
专业分类
测绘学 | 212篇 |
大气科学 | 611篇 |
地球物理 | 745篇 |
地质学 | 1537篇 |
海洋学 | 472篇 |
天文学 | 159篇 |
综合类 | 301篇 |
自然地理 | 265篇 |
出版年
2024年 | 12篇 |
2023年 | 26篇 |
2022年 | 110篇 |
2021年 | 128篇 |
2020年 | 103篇 |
2019年 | 106篇 |
2018年 | 159篇 |
2017年 | 118篇 |
2016年 | 146篇 |
2015年 | 138篇 |
2014年 | 156篇 |
2013年 | 139篇 |
2012年 | 153篇 |
2011年 | 149篇 |
2010年 | 166篇 |
2009年 | 151篇 |
2008年 | 151篇 |
2007年 | 147篇 |
2006年 | 109篇 |
2005年 | 124篇 |
2004年 | 92篇 |
2003年 | 116篇 |
2002年 | 124篇 |
2001年 | 117篇 |
2000年 | 123篇 |
1999年 | 180篇 |
1998年 | 114篇 |
1997年 | 155篇 |
1996年 | 127篇 |
1995年 | 111篇 |
1994年 | 84篇 |
1993年 | 101篇 |
1992年 | 89篇 |
1991年 | 63篇 |
1990年 | 45篇 |
1989年 | 32篇 |
1988年 | 26篇 |
1987年 | 21篇 |
1986年 | 19篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1967年 | 3篇 |
1958年 | 2篇 |
排序方式: 共有4302条查询结果,搜索用时 15 毫秒
51.
Lectotype optimization of offshore platforms is of particular importance in the concept design process. Lectotype optimization involves multiple objectives with uncertainty and so is a problem of multiple attribute decision making. To date, there have been few published works on this topic in the context of offshore engineering. This paper develops a framework and methodology for evaluation of offshore platform alternatives, where a fuzzy optimum model is proposed to integrate the influence of each objective in the criteria set, and a new weight-assessing method is developed to mimic the decision maker’s experience and preference based on complementary pairwise comparisons. A case study shows that the new framework and methodology is scientific, reasonable and easy to use in practice. 相似文献
52.
53.
A Unified Variational Principle of Fluid Mechanics and Application on Solitary Subdomain or Point 总被引:1,自引:0,他引:1
-According to basic equations of fluid mechanics, this paper presents a unified variational principle of fluid mechanics (UVPFM) by using the optimization method of weighted residuals (OMWR). The advantages are as follows, the establishment of the functional and the variational principle is easy, it can change various problems of fluid mechanics derived by basic equations into a unified optimization problem, and the solution is the optimum one in some sense. According to the OMWR for the solitary subdomain, this paper uses UVPFM onto any solitary subdomain and gives the solution of the hydrodynamics equation which is suitable only for that solitary subdomain. According to the OMWR for solitary point, this paper uses UVPFM to any solitary point and gives the solution of the hydrodynamics equation (point solution) which is suitable only for that solitary point. As the solution for the solitary subdomain or solitary point is developed independently, the compatibility with other subdomain or other points, do 相似文献
54.
55.
主要根据台湾海峡的实测海流资料,以夏、冬为代表季节,分析了台湾海峡2—3个纬向断面的海流结构,计算出各断面的海水通量。结果表明:夏季,台湾海峡中、北部海域各层的海流一般偏N向流动,N向的海水净通量为3.32×106m3·s-1;冬季,高温高盐的黑潮水和南海水由南向北经南部断面进入台湾海峡,其海水通量分别为1.69×106m3·s-1和0.59×106m3·s-1;而东海水由北向南通过北部断面进入台湾海峡,其海水通量为1.02×106m3·s-1,其中,有0.40×106m3·s-1的海水沿着福建和广东近岸流进南海,其余0.62×106m3·s-1的海水在台湾海峡北部混合后随同黑潮水和南海水流入东海。总之,流经台湾海峡的N向海水净通量为1.74×106m3·s-1。 相似文献
56.
Wei Rulong Prof. Senior Engineer Geotechnical Engineering Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1994,(1)
-The shear strength and deformation properties of soft clay are discussed first. Then some methods for predicting the performance of soft clay foundation are proposed. Finally, case histories are presented to illustrate some discussed aspects of soft clay. 相似文献
57.
Zhang Jinshan Yu Guohua
Research Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Research Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1995,(3)
- Based on field investigations, this paper analyzes three types of harbour basinns and navigation channel excavated on seabed in Jiaozhou Bay, get a general rule of deposition for excavated trough, it found that pollution is one of crucial factors resulting in the deposition of the excavated trough in the east shore of Jiaozhou Bay. With these results, it predicted the annual deposition thickness for the excavated trough and disclosed the fact that it can't be deposited deadly during one storm. At the same time, with two-dimensional numerical model, it studied the effects of the excavated trough and the reclamation near shore on tidal cureent and said that the excavated trough can decrease the current velocity passing through the trough about 10- 15%, but only limited inside and near the trough and there are no effect on other regions; reclamation can cut off the pollution sources and no obvious effect on the currents of the Jiaozhou Bay. Connecting the deep trough and Cangkou tidal channel with a new 相似文献
58.
北黄海长山群岛海域沉积环境初步研究 总被引:3,自引:0,他引:3
本文在获取1989-1993年黄海北部长山群岛海域沉积物大量数据基础上,借助沉积物粒度分析(Q型),揭示出该海域具有在“岛屿效应”影响下的4种环境能量类型,分析了与其适应的环岛沉积环境及其分布特征。 相似文献
59.
Fu Yongfa 《海洋学报(英文版)》1992,11(2):305-316
On the basis of the four-cruise investigation data of the Kuroshio by the R/V "Xiangyanghong 09", this paper lays stress on the discussion of the relationship between the Kuroshio current systems, the distribution of dissolved oxygen in the northern East China Sea (ECS) and seasonal variations. 相似文献
60.