全文获取类型
收费全文 | 39064篇 |
免费 | 1025篇 |
国内免费 | 1071篇 |
专业分类
测绘学 | 984篇 |
大气科学 | 3001篇 |
地球物理 | 8064篇 |
地质学 | 14369篇 |
海洋学 | 3509篇 |
天文学 | 8376篇 |
综合类 | 243篇 |
自然地理 | 2614篇 |
出版年
2022年 | 297篇 |
2021年 | 488篇 |
2020年 | 490篇 |
2019年 | 520篇 |
2018年 | 957篇 |
2017年 | 921篇 |
2016年 | 1105篇 |
2015年 | 759篇 |
2014年 | 1100篇 |
2013年 | 1964篇 |
2012年 | 1393篇 |
2011年 | 1879篇 |
2010年 | 1636篇 |
2009年 | 2117篇 |
2008年 | 1767篇 |
2007年 | 1818篇 |
2006年 | 1785篇 |
2005年 | 1281篇 |
2004年 | 1184篇 |
2003年 | 1096篇 |
2002年 | 1058篇 |
2001年 | 880篇 |
2000年 | 861篇 |
1999年 | 699篇 |
1998年 | 746篇 |
1997年 | 712篇 |
1996年 | 600篇 |
1995年 | 585篇 |
1994年 | 503篇 |
1993年 | 444篇 |
1992年 | 439篇 |
1991年 | 400篇 |
1990年 | 476篇 |
1989年 | 389篇 |
1988年 | 368篇 |
1987年 | 449篇 |
1986年 | 365篇 |
1985年 | 455篇 |
1984年 | 556篇 |
1983年 | 470篇 |
1982年 | 485篇 |
1981年 | 425篇 |
1980年 | 427篇 |
1979年 | 375篇 |
1978年 | 361篇 |
1977年 | 350篇 |
1976年 | 321篇 |
1975年 | 302篇 |
1974年 | 322篇 |
1973年 | 356篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
Basic exogenic dynamic processes are analysed and discussed. Such processes are actively developed and intensively utilized in mountainous regions of the Baikal-Amur Mainline. Investigation of these regions, which call for reliance on aerospace methods is of considerable economic significance. Translated from: Kosmicheskiye Issledovaniya Prirodnykh Kompleksov Sibiri i Dal'nego Vostoka, Novosibirik, 1983, pp. 57-63. 相似文献
182.
Joel L. Morrison 《地理信息系统科学与遥感》2013,50(4):291-300
The multifaceted career and contributions of Professor Konstantin A. Salishchev, Chair of the Moscow University Department of Cartography and eminent world cartographer, are celebrated on the occasion of his eightieth birthday. These contributions include but are not restricted to: scholarly and administrative work in upgrading national atlas cartography worldwide, improvement of the quality of maps and cartographic instruction in higher education, publication of numerous excellent cartographic texts, formulation of the concept of the “cartographic method of research,” and promotion of international cooperation among cartographers and geographers through active participation and leadership in numerous world professional organizations. From the Russian original by I. D. Papanin, G. I. Rychagov, and A. F. Treshnikov. 相似文献
183.
L. K. Zatonskiy 《地理信息系统科学与遥感》2013,50(2):148-153
A brief review paper focuses on Soviet strategies for the use of space imagery, particularly photographic products (1:2,000,000 to 1:4,200,000 scale) from manned spaceflights, in the revision of small-scale general reference maps. Principles for the interpretation and mapping of basic map elements appearing on space photographs are outlined. Space photographs provide for reduction in time spent in map editing and the more correct analysis of the reliability of information and its generalization. A technology of map revision based on the joint use of original photographs and photomaps, with the transfer of revisions from photomaps to map originals, is proposed. Translated from: Geodeziya i kartografiya, 1986, No. 8, pp. 29-33. 相似文献
184.
A paper devoted to the transformation of cartographic images based on nontraditional systems of scaling (travel time, transport effort, cost, etc.) describes the results of work to develop a more effective algorithm for such transformations, i.e., one which the authors claim provides for the more accurate determination of “transformed” line lengths than possible with earlier methods. Translated from: Izvestiya AN SSSR, seriya geograficheskaya, 1987, No. 4, pp. 105-111. 相似文献
185.
The authors describe strategies for the utilization of digital image processing in the compilation of soil maps at scales of 1:1,000,000 and 1:25,000 for the trans-Volga region of Russia. Particular attention is devoted to an exploration of the effects of variations in soil humus content, texture, and degree of erosion upon spectral brightness coefficients. Results of the mapping demonstrate the promise of digital image processing in the differentiation of a number of chernozem soil subtypes. Translated by Edward Torrey, Alexandria, VA 22308 from: Aerokosmicheskiye metody v pochvovedenii i ikh ispol'zovaniye v sel'skom khozyaystve: sbornik nauchnykh trudov [Remote Sensing Methods in Soil Science and Their Utilization in Agriculture: A Collection of Scientific Works]. Moscow: Nauka, 1990, pp. 214–225. 相似文献
186.
Another paper in a series of articles on ecological-geographic mapping (see for example, Mapping Sciences and Remote Sensing, Vol. 31, No. 3, July-September 1994, pp. 185-220) focuses on outlining a concise typology of such maps and providing a brief history of their emergence during the 1970s and 1980s. A subsequent section is devoted to methods and technology used in the compilation of ecological-geographic maps, particularly the multiple variants of data organization, processing, and cartographic representation that can be factored into research design. Translated by Edward Torrey, Alexandria, VA 22308 from: Geografiya i prirodnyye resursy, 1995, No. 4, pp. 10-18. 相似文献
187.
QuickBird satellite imagery acquired in June 2003 and September 2004 was evaluated for detecting the noxious weed spiny aster [Leucosyris spinosa (Benth.) Greene] on a south Texas, USA rangeland area. A subset of each of the satellite images representing a diversity of cover types was extracted and used as a study site. The satellite imagery had a spatial resolution of 2.8 m and contained 11-bit data. Unsupervised and supervised classification techniques were used to classify false colour composite (green, red, and near-infrared bands) images of the study site. Imagery acquired in June was superior to that obtained in September for distinguishing spiny aster infestations. This was attributed to differences in spiny aster phenology between the two dates. An unsupervised classification of the June image showed that spiny aster had producer's and user's accuracies of 90% and 93.1%, respectively, whereas a supervised classification of the June image had producer's and user's accuracies of 90% and 81.8%, respectively. These results indicate that high resolution satellite imagery coupled with image analysis techniques can be used successfully for detecting spiny aster infestations on rangelands. 相似文献
188.
189.
Abstract Image mapping using data from visible and infrared sensors has, as a major drawback, the frequent cloud cover experienced in many countries. This is one of the main reasons why topographic maps at 1:100,000 scale and larger are often outdated. The results of a study which investigated the possibilities of fusing up‐to‐date spaceborne microwave data with existing images from optical sensors for topographic map updating at a scale of 1:100, 000 are presented in this paper. A key issue researched was the influence of geometric distortions and corrections of remote sensing data on the results of pixel based digital image fusion. After having terrain‐geocoded and radiometrically enhanced imagery from the Landsat, SPOT, ERS‐1 and JERS‐1 satellites, the data were fused applying a variety of colour transformation techniques as well as statistical or arithmetic methods. Initially, the image fusion was implemented using images covering a test site in the north of The Netherlands in order to calibrate specified combinations and techniques in a rather flat area. With the experience gained, the remote sensing data acquired over the research site were processed. The research test site is located in a typical Developing Country in the humid Tropics, on the mountainous south‐west coast of Sumatra in Indonesia. The results of the various applied techniques and image combinations were evaluated with reference to their capability to overcome the cloud cover problem. New combinations of techniques and images were developed as result of an optimisation process. The research produced two prototypes of annotated 1:100,000 scale image maps containing fused, cloud‐free optical/microwave imagery. 相似文献
190.
提出一种在测站没有定向点的情况下,利用全站仪进行碎部测量的作业方法,阐述该方法的作业过程、精度情况和注意事项,为解决全野外数字测图过程中经常遇到的由于控制点无通视方向而影响碎部测量作业的问题提供了有效途径。 相似文献