全文获取类型
收费全文 | 1211篇 |
免费 | 254篇 |
国内免费 | 290篇 |
专业分类
测绘学 | 142篇 |
大气科学 | 214篇 |
地球物理 | 285篇 |
地质学 | 650篇 |
海洋学 | 259篇 |
天文学 | 5篇 |
综合类 | 78篇 |
自然地理 | 122篇 |
出版年
2024年 | 8篇 |
2023年 | 18篇 |
2022年 | 28篇 |
2021年 | 37篇 |
2020年 | 50篇 |
2019年 | 48篇 |
2018年 | 39篇 |
2017年 | 51篇 |
2016年 | 63篇 |
2015年 | 58篇 |
2014年 | 64篇 |
2013年 | 110篇 |
2012年 | 76篇 |
2011年 | 71篇 |
2010年 | 69篇 |
2009年 | 69篇 |
2008年 | 93篇 |
2007年 | 83篇 |
2006年 | 78篇 |
2005年 | 75篇 |
2004年 | 86篇 |
2003年 | 68篇 |
2002年 | 49篇 |
2001年 | 42篇 |
2000年 | 48篇 |
1999年 | 21篇 |
1998年 | 42篇 |
1997年 | 29篇 |
1996年 | 26篇 |
1995年 | 18篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1972年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有1755条查询结果,搜索用时 15 毫秒
11.
12.
Ahna L. Van Gaest Craig M. Young John J. Young Alicia R. Helms & Shawn M. Arellano 《Marine Ecology》2007,28(1):199-207
Bathynerita naticoidea (Gastropoda: Neritidae) and Methanoaricia dendrobranchiata (Polychaeta: Orbiniidae) are two of the most abundant invertebrates associated with cold‐seep mussel beds in the Gulf of Mexico. At the methane seep known as Brine Pool NR‐1 (27 °43.415 N, 91 °16.756 W; 650 m depth), which is surrounded by a broad band of mussels (Bathymodiolus childressi), these species have distinctly different patterns of abundance, with the gastropod being found mostly at the outer edge of the mussel bed (average density in November 2003: 817 individuals·m−2 in outer zone, 20·m−2 in inner zone) and the polychaete being found almost exclusively near the inner edge (average density in November 2003: 3155 individuals·m−2 in inner zone, 0·m−2 in outer zone), adjacent to the brine pool itself. The salinity of the brine pool exceeds 120, so we hypothesized that M. dendrobranchiata should be more tolerant of high salinities than B. naticoidea. The opposite proved to be true. The gastropods were capable of withstanding salinities at least as high as 85, whereas the polychaetes died at salinities higher than 75. Both species were osmoconformers over the range of salinities (35–75) tested. Behavioral responses of B. naticoidea to salinities of 50, 60, and 70 were investigated in inverted vertical haloclines. Gastropods generally did not enter water of salinity greater than 60, but tolerated short periods at 60. Behavioral avoidance of brine should limit the vertical distribution of B. naticoidea in the inner zone to the top 2.5–5 cm of the mussel bed. Behavior is also a likely (though unproven) mechanism for controlling horizontal distribution of this species across the mussel bed. Methanoaricia dendrobranchiata can tolerate short excursions into the brine, but probably avoids hypersaline conditions by aggregating on the tops of the mussels. 相似文献
13.
Jean-Marie Auzende Eiichi Honza Xavier Boespflug Satendra Deo Jean-Philippe Eissen Jun Hashimoto Philippe Huchon Junichiro Ishibashi Yo Iwabuchi Philip Jarvis Masato Joshima Kiyoyuki Kisimoto Yasuto Kuwahara Yves Lafoy Tsuyoshi Matsumoto Jean-Pierre Maze Kiyohiko Mitsuzawa Hiroyasu Monma Takeshi Naganuma Yukihiro Nojiri Suguru Ohta Kiyoshi Otsuka Yoshihisa Okuda Hélène Ondreas Akira Otsuki Etienne Ruellan Myriam Sibuet Manabu Tanahashi Takeo Tanaka Tetsuro Urabe 《Marine Geophysical Researches》1990,12(4):269-283
The aim of the Japanese-French Kaiyo 87 cruise was the study of the spreading axis in the North Fiji Basin (SW Pacific). A
Seabeam and geophysical survey allowed us to define the detailed structure of the active NS spreading axis between 16° and
22° S and its relationships with the left lateral motion of the North Fiji Fracture Zone. Between 21° S and 18°10′ S, the
spreading axis trends NS. From 18°10 S to 16°40 S the orientation of the spreading axis changes from NS to 015°. North of
16°40′ S the spreading axis trends 160°. These two 015° and 160° branches converge with the left lateral North Fiji fracture
zone around 16°40′ S to define an RRFZ triple junction. Water sampling, dredging and photo TV deep towing give new information
concerning the hydrothermal activity along the spreading axis. The discovery of hydrothermal deposits associated with living
communities confirms this activity. 相似文献
14.
TOGA—COARE强化观测期间,对赤道暖池区海流作了多种方法、多层次的观测;根据美国释放的漂流浮标不同时刻位置的资料,分别对赤道及其南、北海域的表层漂流状况作了计算分析,指出:从1°N向北存在单一的北向流;从1°N~1°S这个近赤道区域内为东向流;1°N~2°S区域为过渡区,以东向流为主,个别浮标出现涡旋状运动。2°S以南为一反时针运动的大涡旋。 相似文献
15.
本文给出了“包装产品的计量标准型一次抽检方案”,并通过一个实例说明本方案比一般《计量标准型一次抽检方案》更为优越。 相似文献
16.
How are large western hemisphere warm pools formed? 总被引:1,自引:0,他引:1
During the boreal summer the Western Hemisphere warm pool (WHWP) stretches from the eastern North Pacific to the tropical North Atlantic and is a key feature of the climate of the Americas and Africa. In the summers following nine El Niño events during 1950–2000, there have been five instances of extraordinarily large warm pools averaging about twice the climatological annual size. These large warm pools have induced a strengthened divergent circulation aloft and have been associated with rainfall anomalies throughout the western hemisphere tropics and subtropics and with more frequent hurricanes. However, following four other El Niño events large warm pools did not develop, such that the mere existence of El Niño during the boreal winter does not provide the basis for predicting an anomalously large warm pool the following summer.In this paper, we find consistency with the hypothesis that large warm pools result from an anomalous divergent circulation forced by sea surface temperature (SST) anomalies in the Pacific, the so-called atmospheric bridge. We also find significant explanations for why large warm pools do not always develop. If the El Niño event ends early in the eastern Pacific, the Pacific warm anomaly lacks the persistence needed to force the atmospheric bridge and the Atlantic portion of the warm pool remains normal. If SST anomalies in the eastern Pacific do not last much beyond February of the following year, then the eastern North Pacific portion of the warm pool remains normal. The overall strength of the Pacific El Niño does not appear to be a critical factor. We also find that when conditions favor a developing atmospheric bridge and the winter atmosphere over the North Atlantic conforms to a negative North Atlantic Oscillation (NAO) pattern (as in 1957–58 and 1968–69), the forcing is reinforced and the warm pool is stronger. On the other hand, if a positive NAO pattern develops the warm pool may remain normal even if other circumstances favor the atmospheric bridge, as in 1991–92. Finally, we could find little evidence that interactions internal to the tropical Atlantic are likely to mitigate for or against the formation of the largest warm pools, although they may affect smaller warm pool fluctuations or the warm pool persistence. 相似文献
17.
18.
19.
C. M. Laluraj K. K. Balachandran P. Sabu S. U. Panampunnayil 《Marine Geophysical Researches》2006,27(4):283-288
This study delineates the formation of a warm pool (>34°C) of air to the west (downwind) of the active volcano of the Barren Island during October–November 2005. Barren Island is located in the Sumatra–Andaman region, about 135 km east of Port Blair, and lies within the Burma microplate, the southern tip of which experienced a submarine earthquake (M
w 9.3) causing a tsunami in December 2004. Barren Island is the only volcano, which has shown sustained eruptive activity since shortly after the Great Sumatran Earthquake of December 2004. Our observations require further corroboration to relate how submarine earthquakes activate volcanoes and how far these thermal emissions influence climate changes. Because it links global warming and climate changes to the frequent emissions from a volcano activated by submarine earthquakes, this case study is of special interest to the earth-ocean-atmosphere sciences community. 相似文献
20.
Sampling permeability from individual laminae in crossbedded rocks is very well possible by making use of a so-called probe permeameter. The methodology and calculation of permeabilities from the output of this instrument are fairly well-established. However, what is hardly established is a sampling strategy that guarantees adequate representation of permeability contrast between laminae. Especially so, because finer foreset and bottomset are difficult to sample, yet their permeabilities are critical to fluid flow through a crossbed. Therefore we propose to systematically sample laminae. To this end we suggest a sampling strategy that is adapted to the heterogeneity under study, namely to the thickness of the finer foreset. 相似文献