全文获取类型
收费全文 | 313篇 |
免费 | 16篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 25篇 |
地球物理 | 85篇 |
地质学 | 81篇 |
海洋学 | 59篇 |
天文学 | 55篇 |
综合类 | 2篇 |
自然地理 | 24篇 |
出版年
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2014年 | 13篇 |
2013年 | 13篇 |
2012年 | 9篇 |
2011年 | 13篇 |
2010年 | 23篇 |
2009年 | 20篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有332条查询结果,搜索用时 78 毫秒
141.
Mid-infrared extinction coefficients of five natural amorphous silicates and seven synthetic glasses were measured. Three bands at about 10, 12, and 20 μm were seen for all the measured samples. The quantities of these bands are found to have good correlations with the SiO2 content of the samples. The correlations are the most remarkable for the 10 μm band. As the SiO2 content decreases, the peak wavelengthλ m shifts to longer side, the peak heightK m decreases and the full width of half maximumW increases. A quantityλ m K m W is constant within 15%. Empirical formula $$\lambda_m (\mu m) = {11.10-2.30 x 10^-2} {[SiO_2 wt.\%]} \pm 0.15$$ and $$W(\mu m) = {5.14-4.68 x 10^- 2} {[SiO_2 wt.\%]} \pm 0.30$$ are obtained for the measured samples. Therefore, the correlation is present between the 10 μm peak wavelengthλ m and peak widthW for amorphous silicates. The change in peak widthW is remarkable compared the change in peak wavelengthλ m as the SiO2 content varies. For the 12 μm band the correlations with the SiO2 content are not so good. A tendency that theλ m shifts to the red and theK m lowers as the decreasing SiO2 content are found. For the samples with SiO2 content less than 50% the 12 μm band cannot recognized as the peak. For the 20 μm band, theλ m is almost independent on SiO2 content and theK m lowers with decreasing SiO2 content. The results are compared with the observed 10 μm band of the astronomical objects. A method to estimate the SiO2 content of astronomical grain materials is proposed and 48±8% SiO2 wt.% is found corresponding to the peak wavelength of 9.7 μm and the peak width of 2.5–3.0 μm of typical celestial objects. 相似文献
142.
Ikawa Hiroki Kuwagata Tsuneo Haginoya Shigenori Ishigooka Yasushi Ono Keisuke Maruyama Atsushi Sakai Hidemitsu Fukuoka Minehiko Yoshimoto Mayumi Ishida Sachinobu Chen Charles P. Hasegawa Toshihiro Watanabe Tsutomu 《Boundary-Layer Meteorology》2021,179(3):447-476
Boundary-Layer Meteorology - Known as the heat-mitigation effect, irrigated rice-paddy fields distribute a large fraction of their received energy to the latent heat during the growing season. The... 相似文献
143.
We present high resolution CS and CO maps of Cep A region made with the 45m telescope at Nobeyama. The CS map shows that a dense cloud surrounding the proto-star cluster extends in the North-South direction and is probably rotating. The bipolar molecular flow apparent in the CO maps is well-collimated along East-West direction within 0.2 pc from the proto-stars. The dense cloud is gravitationally unstable and appears to be in a contracting phase to form a cluster of massive stars.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.NRO, a branch of the Tokyo Astronomical Observatory, University of Tokyo, is a cosmic radio observing facility open for outside users. 相似文献
144.
Takayuki Shiozawa Akira Hoshika Osamu Takimura Terumi Tanimoto 《Journal of Oceanography》1982,38(1):15-20
Vertical and horizontal distributions of manganese in Harima Sound (Harima Nada, Seto Inland Sea) were measured in August and December 1979. High concentrations of dissolved and particulate manganese were found in bottom waters in August, suggesting that the bottom enrichment is probably due to the diffusion of dissolved manganese out of the sediment. From measured distributions, we estimate the annual flux of manganese at the sediment-water interface to be more than 800 tons per year, if Harima Sound is a closed system for manganese. 相似文献
145.
The plate culture method using the two formulae for non-nitrogenous media was adopted in this investigation for the purpose
of counting and isolating nitrogen-fixing bacteria distributed in the open sea.
Sea water samples were collected at eighteen different stations in the region of Lat. 50°N–15°S along Long. 155°W and two
other stations in the Pacific Ocean. In order to compare with those samples from the open sea, water samples were also obtained
at four stations in Suruga and Sagami Bays.
Nitrogen-fixing bacteria appear to be widely but very unevenly distributed at all depths in sea water, in numbers approximately
ranging from nil to 104 per 100 ml of sea water, and denser vertical populations have been found in the area of Lat. 40°N and 5°N along Long. 155°W, even at
depths from 2,000 to 3,000m. A conparatively denser population of bacteria was found in sea water from Suruga Bay and Sagami
Bay.
The bacteria associated with plankton were abundantly demonstrated, in numbers ranging from 106 to 108 per 1 ml settling volume of plankton, in many plankton samples collected at four stations in the southern parts of the Pacific Ocean.
Almost all the bacteria isolated from the samples of blue green algal colonies,Trichodesmium, sp., were able to grow on nonnitrogeneous media. 相似文献
146.
Rates of urea supply from the decomposition and the excretion of zooplankton were determined for samples collected in Suruga
Bay. Five species of Zooplankton were incubated in filtered seawater at 20‡C for 276 hrs after being forced to die in a refrigerator.
More than 77.6 % of body nitrogen of the Zooplankton was liberated, except forEuphausia similis, which showed a lower decomposition rate of 53.0 %. In the liberated nitrogen. 4.8 to 9.8 % was determined as urea.
Incubation experiments of two species of zooplankton at 13‡C during 12 hrs, showed that the organisms excreted 0.86 and 0.73Μg-at. N indi.−1 d−1 as total soluble nitrogen. Urea accounted for 8.3 and 6.8 % of the excreted total soluble nitrogen. 相似文献
147.
The distribution of pelagic blue-green algae, especially ofTrichodesmium thiebautii, was investigated on the basis of the collection of theHakuhō Maru Cruise KH-69-4 along 155°W (50°N-15°S) in the North Pacific Ocean from September to November 1969.
- Five species were identified:Trichodesmium thiebautii (most predominant),T. erythraeum, Oscillatoria sp.,Katagnymene spiralis andRichelia intracellularis.
- T. thiebautii was most abundant in the western North Pacific central water and abundant next to it in the equatorial water, but it did not occur in the subarctic water.
- T. thiebautii was ubiquitously distributed in the lower layer of 100–200 m in the equatorial water, though not in a large quantity.
- T. thiebautii inhabited only the water warmer than 20°C. In its main habitat, nitrate and nitrite were almost zero, but ammonia and phosphate were present. There was not found any correlation between its occurrence and the salinity.
- Blue-green algae were generally thinly populated in the water rich in diatoms.
148.
Osamu Katoh Kazuyuki Teshima Katsuhiko Kubota Kazuo Tsukiyama 《Journal of Oceanography》1996,52(1):93-108
In order to clarify detailed current structures west of Kyushu, ADCP measurements were carried out in July and September 1990 by the quadrireciprocal method (Katoh, 1988) for removing diurnal and semidiurnal tidal flows from observed flows. On the basis of these results, together with data of routine oceanographic observations, we study the downstream transition of the Tsushima Current west of Kyushu in summer. In the southwest of the Goto Islands, a northward current identified as the Tsushima Current was clearly found. In the south of Cheju, a westward current bifurcated from the Tsushima Current. In the northwest of the Goto Islands, the Tsushima Current narrowed and its velocity became strengthened. Salinity of the Tsushima Current water was much diluted by a current from the Cheju Strait. Near the west coast of the Goto Islands, a countercurrent bifurcating from the Tsushima Current often occurred. The volume transport of the Tsushima Current was 2.3 Sv (1 Sv=106 m3s–1) on the northern side of latitude 31°N. The substantial bifurcation of the Tsushima Current toward the Eastern and Western Channels of the Tsushima Strait occurred in the vicinity of Tsushima. The volume transport through the Western Channel was two to three times larger than that through the Eastern Channel. The baroclinic component in volume transport of the Tsushima Current west of Kyushu was much smaller than that in the Japan Sea. 相似文献
149.
Around the thermocline, difference in the depth of the maximum concentration between particulate manganese and iron was observed above the basin located at the south-western corner of the Beppu Bay, along with the remarkable difference in pH and Eh. 相似文献
150.
Direct measurements of the air-sea CO2 flux by the eddy covariance technique were carried out in the equatorial Indian Ocean. The turbulent flux observation system
was installed at the top of the foremast of the R/V MIRAI, thus minimizing dynamical and thermal effects of the ship body.
During the turbulent flux runs around the two stations, the vessel was steered into the wind at constant speed. The power
spectra of the temperature or water vapor density fluctuations followed the Kolmogorov −5/3 power law, although that of the
CO2 density fluctuation showed white noise in the high frequency range. However, the cospectrum of the vertical wind velocity
and CO2 density was well matched with those of the vertical velocity and temperature or water vapor density in this frequency range,
and the CO2 white noise did not influence the CO2 flux. The raw CO2 fluxes due to the turbulent transport showed a sink from the air to the ocean, and had almost the same value as the source
CO2 fluxes due to the mean vertical flow, corrected by the sensible and latent heat fluxes (called the Webb correction). The
total CO2 fluxes including the Webb correction terms showed a source from the ocean to the air, and were larger than the bulk CO2 fluxes estimated using the gas transfer velocity by mass balance techniques. 相似文献