全文获取类型
收费全文 | 47946篇 |
免费 | 443篇 |
国内免费 | 372篇 |
专业分类
测绘学 | 1380篇 |
大气科学 | 3409篇 |
地球物理 | 8456篇 |
地质学 | 19781篇 |
海洋学 | 3757篇 |
天文学 | 9860篇 |
综合类 | 195篇 |
自然地理 | 1923篇 |
出版年
2021年 | 199篇 |
2020年 | 238篇 |
2019年 | 298篇 |
2018年 | 3599篇 |
2017年 | 3376篇 |
2016年 | 2305篇 |
2015年 | 533篇 |
2014年 | 727篇 |
2013年 | 1301篇 |
2012年 | 1874篇 |
2011年 | 3732篇 |
2010年 | 3479篇 |
2009年 | 3850篇 |
2008年 | 3104篇 |
2007年 | 3779篇 |
2006年 | 1171篇 |
2005年 | 1310篇 |
2004年 | 1206篇 |
2003年 | 1211篇 |
2002年 | 966篇 |
2001年 | 643篇 |
2000年 | 674篇 |
1999年 | 563篇 |
1998年 | 556篇 |
1997年 | 523篇 |
1996年 | 395篇 |
1995年 | 394篇 |
1994年 | 408篇 |
1993年 | 313篇 |
1992年 | 308篇 |
1991年 | 258篇 |
1990年 | 310篇 |
1989年 | 270篇 |
1988年 | 254篇 |
1987年 | 279篇 |
1986年 | 237篇 |
1985年 | 317篇 |
1984年 | 338篇 |
1983年 | 329篇 |
1982年 | 313篇 |
1981年 | 263篇 |
1980年 | 285篇 |
1979年 | 216篇 |
1978年 | 206篇 |
1977年 | 215篇 |
1976年 | 183篇 |
1975年 | 190篇 |
1974年 | 177篇 |
1973年 | 167篇 |
1972年 | 114篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
411.
Distributions of physical, chemical and biological characteristics were recorded for coastal waters off south-west Ireland during the summers of 1985–1987. A number of thermal fronts were identified from both shipboard measurements and satellite imagery. Upwelling was shown to be an important process in the area and enhanced phytoplankton biomass and productivity were associated with areas of upwelling and the fronts. Phytoplankton species composition, although varying between cruises, was associated with differences in hydrographic features. 相似文献
412.
413.
We perform the analysis of the time spectra of four tsunamis generated in the Black Sea by the earthquakes of 26.07.1927,
11.09.1927, 26.12.1939, and 12.07.1966. For the analysis of the spectra, we used digitized marigrams obtained for 12 points
of the Black-Sea coast. The obtained spectra are, as a rule, multimode and have 1–4 spectral maxima. One maximum corresponds
to the periods typical of tsunami waves and the other maxima correspond to the oscillations of the sea level with lower frequencies.
It seems likely that the events of tsunami are accompanied by low-frequency oscillations of the level caused by the atmospheric
forcing, seiches, or other factors. In numerous cases, the oscillations from the predominant energy range lie outside the
characteristic range of periods of the tsunami waves.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 21–30, September–October, 2007. 相似文献
414.
415.
416.
Juvenile coho salmon, Onchorynchus kisutch, were exposed to 95mTc in both saltwater and freshwater to study the biokinetic behavior of this element in an anadromous fish. In freshwater, equilibrium whole-body concentration factors (CF5) ranged from 28 to 32 in two separate experiments, in sharp contrast to an equilibriumCF of < 5 in saltwater. While the uptake kinetics were unimodal in saltwater, in freshwater, biomodal uptake kinetics were observed.Technetium-95m retention was biphasic in freshwater depuration experiments, an initial rapid loss of 21% to 26% of the steady-state activity with an elimination half-life of 3 to 5 days was followed by a slower loss rate, with a whole-body elimination half-life ranging from 23 to 33 days. In saltwater, retention was monophasic with an elimination half-life of 5–16 days. Dramatic decreases in 95mTc body burdens when freshwater-labeled fish are transferred to Tc-labeled saltwater indicate that the changes in physiology accompanying saltwater acclimation lead to the loss of 95mTc. 相似文献
417.
418.
We study the processes of global self-regulation of Earth’s biota (GAIA-theory) by applying the method of adaptive balance of causes proposed by the authors. By using, as an example, the Daisy World model constructed by this method, we reveal the phenomenon of preservation of the mean temperature of Earth’s surface due
to the presence of the vegetation cover. We develop an integral model of global natural, social, and economic processes in
which the World Ocean is one of the factors regulating the amount of greenhouse gases in the atmosphere. The decrease in the
amount of greenhouse gases in the atmosphere caused by the GAIA-effects increases the number of hurricanes and floods on the Earth. As a result, the levels of ecological and social hazards
for the mankind become much higher. To eliminate these threats, it is necessary to intensify the processes of self-organization
of the society realized via the improvement of education, development of science, and global regulation of the competition
for natural resources. We present the results of numerical experiments performed by using the model demonstrating possible
scenarios of global development with regard for the processes of self-organization of the society.
__________
Translated From Morskoi Gidrofizicheskii Zhurnal, No. 3, Pp. 62–80, May–June, 2007. 相似文献
419.
420.
The wadic project: A comprehensive field evaluation of directional wave instrumentation 总被引:1,自引:0,他引:1
J. Allender T. Audunson S. F. Barstow S. Bjerken H. E. Krogstad P. Steinbakke L. Vartdal L. E. Borgman C. Graham 《Ocean Engineering》1989,16(5-6)
The results of a comprehensive field trial of nearly all commercially available directional wave measurement systems at the Edda field in the North Sea during winter 1985-86 are presented. The results summarize the accuracy of the principal engineering wave parameters from each system and the dependence on sea state. Limiting factors on system performance and operational problems are also included in the assessment. Overall experience has been good with systems utilizing widely different measurement principles returning consistent results. 相似文献