全文获取类型
收费全文 | 51100篇 |
免费 | 500篇 |
国内免费 | 265篇 |
专业分类
测绘学 | 1369篇 |
大气科学 | 3803篇 |
地球物理 | 9162篇 |
地质学 | 21376篇 |
海洋学 | 3937篇 |
天文学 | 9650篇 |
综合类 | 209篇 |
自然地理 | 2359篇 |
出版年
2021年 | 269篇 |
2020年 | 297篇 |
2019年 | 297篇 |
2018年 | 3653篇 |
2017年 | 3423篇 |
2016年 | 2353篇 |
2015年 | 584篇 |
2014年 | 820篇 |
2013年 | 1555篇 |
2012年 | 1958篇 |
2011年 | 3854篇 |
2010年 | 3498篇 |
2009年 | 3843篇 |
2008年 | 3092篇 |
2007年 | 3730篇 |
2006年 | 1186篇 |
2005年 | 1294篇 |
2004年 | 1181篇 |
2003年 | 1201篇 |
2002年 | 1018篇 |
2001年 | 734篇 |
2000年 | 705篇 |
1999年 | 518篇 |
1998年 | 491篇 |
1997年 | 571篇 |
1996年 | 438篇 |
1995年 | 470篇 |
1994年 | 465篇 |
1993年 | 372篇 |
1992年 | 382篇 |
1991年 | 353篇 |
1990年 | 358篇 |
1989年 | 326篇 |
1988年 | 334篇 |
1987年 | 358篇 |
1986年 | 317篇 |
1985年 | 417篇 |
1984年 | 408篇 |
1983年 | 441篇 |
1982年 | 410篇 |
1981年 | 372篇 |
1980年 | 418篇 |
1979年 | 320篇 |
1978年 | 299篇 |
1977年 | 293篇 |
1976年 | 264篇 |
1975年 | 259篇 |
1974年 | 267篇 |
1973年 | 254篇 |
1971年 | 172篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Danukalova M. K. Kuzmichev A. B. Bagaeva A. A. Tolmacheva T. Yu. 《Lithology and Mineral Resources》2022,57(1):44-61
Lithology and Mineral Resources - Sedimentological features of the Upper Cambrian–Middle Ordovician rocks exposed in eastern Taimyr in the Faddey Gulf area are discussed. The studied sections... 相似文献
2.
Frolova N. L. Magritskii D. V. Kireeva M. B. Grigor’ev V. Yu. Gelfan A. N. Sazonov A. A. Shevchenko A. I. 《Water Resources》2022,49(3):333-350
Water Resources - Publications on changes in river water regime in Russia under the conditions of current climate changes are reviewed. Most recent generalizations of such publications are... 相似文献
3.
J.J. Butler Jr S. Knobbe E.C. Reboulet D.O. Whittemore B.B. Wilson G.C. Bohling 《Ground water》2021,59(6):808-818
Many of the world's major aquifers are under severe stress as a result of intensive pumping to support irrigated agriculture and provide drinking water supplies for millions. The question of what the future holds for these aquifers is one of global importance. Without better information about subsurface conditions, it will be difficult to reliably assess an aquifer's response to management actions and climatic stresses. One important but underutilized source of information is the data from monitoring well networks that provide near-continuous records of water levels through time. Most organizations running these networks are, by necessity, primarily focused on network maintenance. The result is that relatively little attention is given to interpretation of the acquired hydrographs. However, embedded in those hydrographs is valuable information about subsurface conditions and aquifer responses to natural and anthropogenic stresses. We demonstrate the range of insights that can be gleaned from such hydrographs using data from the High Plains aquifer index well network of the Kansas Geological Survey. We show how information about an aquifer's hydraulic state and lateral extent, the nature of recharge, the hydraulic connection to the aquifer and nearby pumping wells, and the expected response to conservation-based pumping reductions can be extracted from these hydrographs. The value of this information is dependent on accurate water-level measurements; errors in those measurements can make it difficult to fully exploit the insights that water-well hydrographs can provide. We therefore conclude by presenting measures that can help reduce the potential for such errors. 相似文献
4.
Onishchenko O. G. Pokhotelov O. A. Belyaev V. S. Zagreev B. V. Matafonov A. P. 《Geomagnetism and Aeronomy》2021,61(1):25-28
Geomagnetism and Aeronomy - A new analytical model for the generation of axially symmetric jets (directed jets) in a nondissipative, nonequilibrium stratified plasma has been created in the... 相似文献
5.
Shakirov R. B. Cuong Do Huy Obzhirov A. I. Valitov M. G. Lee N. S. Legkodimov A. A. Kalgin V. Yu. Yeskova A. I. Proshkina Z. N. Telegin Yu. A. Storozhenko A. V. Ivanov M. V. Pletnev S. P. Sedin V. T. Bulanov A.V. Shvalov D. A. Lipinskaya N. A. Bovsun M. A. Makseev D. S. Thanh Nguyen Trung Anh Le Duc Luong Le Duc 《Oceanology》2021,61(1):147-149
Oceanology - Abstract—The paper gives brief results of comprehensive studies in the South China Sea obtained from a joint Russian–Vietnamese expedition in November 2019 (cruise 88 of... 相似文献
6.
Astronomy Letters - The emission from the Crab nebula exhibits a significant gamma-ray variability. In this paper we have analyzed this variability in terms of periodicity. Using the pulsar... 相似文献
7.
Astrophysics - We study the modulation of galactic cosmic rays due to magnetic clouds observed during solar cycles 23 and 24 (1996-2018). We utilize solar wind plasma and field data together with... 相似文献
8.
Motovilov Yu. G. Golosov S. D. Datsenko Yu. S. Zverev I. S. Puklakov V. V. Fashchevskaya T. B. 《Water Resources》2020,47(5):751-762
Water Resources - An Information–Modeling Complex has been developed for the information support of managerial decision making in the field of rational use, protection, and restoration of... 相似文献
9.
Miguel B. Brito Mitsuyoshi Akiyama Yoshitaka Ichikawa Hiroki Yamaguchi Riki Honda Naomitsu Ishigaki 《地震工程与结构动力学》2020,49(8):817-837
A novel low-cost friction sliding system for bidirectional excitation is developed to improve the seismic performance of reinforced concrete (RC) bridge piers. The sliding system is a spherical prototype developed by combining a central flat surface with an inclined spherical segment, characterized by stable oscillation and a large reduction in response accelerations on the flat surface. The inclined part provides a restoring force that limits the residual displacements of the system. Conventional steel and concrete are employed to construct a flat-inclined spherical surface atop an RC pier. The seismic forces are dissipated through the frictions generated during the sliding movements; hence, the seismic resilience of bridges can be ensured with a low-cost design solution. The proposed system is fabricated utilizing a mold created by a three-dimensional printer, which facilitates the use of conventional concrete to construct spherical shapes. The concrete surface is lubricated with a resin material to prevent abrasion from multiple input ground motions. To demonstrate the effectiveness of the system, bidirectional shaking table tests are conducted in the longitudinal and transverse directions of a scaled bridge model. The effect of the inclination angle and the flat surface size is investigated. The results demonstrate a large decrease in response acceleration when the system exhibits circular sliding displacement. Furthermore, the inclination angle that generates the smallest residual displacement is identified experimentally. 相似文献
10.
Oceanology - In November 2020, the invasive ctenophore Beroe ovata Bruguière, 1789 was recorded in samples of gelatinous zooplankton from the northern and central parts of the Caspian Sea. The... 相似文献