全文获取类型
收费全文 | 198篇 |
免费 | 9篇 |
国内免费 | 16篇 |
专业分类
大气科学 | 14篇 |
地球物理 | 55篇 |
地质学 | 46篇 |
海洋学 | 42篇 |
天文学 | 44篇 |
综合类 | 4篇 |
自然地理 | 18篇 |
出版年
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 10篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 14篇 |
2006年 | 6篇 |
2005年 | 14篇 |
2004年 | 7篇 |
2003年 | 13篇 |
2002年 | 2篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有223条查询结果,搜索用时 15 毫秒
81.
Aierken Sidike Keyoumu Niyazi Heng-Jiang Zhu K. Atobe N. Yamashita 《Physics and Chemistry of Minerals》2009,36(3):119-126
The photoluminescence (PL) spectra, excitation spectra, and PL decay curves of natural, heat-treated, and γ-ray-irradiated
thenardites from Ai-Ding Salt Lake, Xinjiang, China, were studied. The natural thenardite under 300 nm excitation showed milk-white
luminescence, and the PL spectrum consisted of an extremely broad band with a peak located at approximately 509 nm, spreading
over a wide range of UV and visible wavelengths. The excitation spectra, obtained by monitoring the luminescence at 530 nm,
consisted of a broad band with a peak located at approximately 235 nm and a flat band spreading over a wide range of UV and
visible wavelengths. The PL decay curve of natural thenardite consisted of a fast-decay component with a lifetime of less
than 0.1 μs and a slow-decay component with a half-decay time of approximately 0.4 s. The heat treatment of thenardite at
900°C for 20 min reduced the luminescence efficiency to 1/100. The γ-ray irradiation of thenardite reduced the luminescence
efficiency to approximately half. 相似文献
82.
Miyake Y Jiang Q Yuan W Hanari N Okazawa T Wyrzykowska B So MK Lam PK Yamashita N 《Marine pollution bulletin》2008,57(6-12):357-364
Dietary intake is one of the important routes of human exposure to brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs). The use of PBDEs may also result in exposure to polybrominated dibenzo-p-dioxins and dibenzofurans (PBDDs/DFs), as these compounds are impurities in technical mixtures of BFRs and can also be formed unintentionally by the same processes that generate chlorinated dioxins. This study determined the concentrations of polybrominated compounds in common seafood in Guangzhou and Zhoushan, and assessed the health risks of these chemicals via consumption of contaminated seafood. Seafood samples (fish, bivalves, shrimp, crab, and cephalopods) purchased from local markets in 2003 and 2004 were analyzed for PBDEs and PBDDs/DFs. The highest concentration of total PBDEs (46.3 ng g(-1) lipid wt.) was detected in fish from Guangzhou, in which BDEs 47 and 209 were the two predominant congeners. The total daily intakes of PBDEs, PBDDs, and PBDFs were, 946, 6.39, and 6.54 pg kg(-1) body weight (bw) in Guangzhou, and 489, 4.99, and 7.65 pg kg(-1) bw in Zhoushan, respectively. The hazard ratios for PBDDs and PBDFs were both greater than unity, indicating that these compounds may pose some health risks to the local population. 相似文献
83.
The phase of semi-diurnal tides (M2 and S2) propagates clockwise in the central part of the Gulf of Thailand, although that of the diurnal tides (K1, O1 and P1) is counterclock-wise. The mechanism of clockwise phase propagation of semi-diurnal tides at the Gulf of Thailand in the
northern hemisphere is examined using a simple numerical model. The natural oscillation period of the whole Gulf of Thailand
is near the semi-diurnal period and the direction of its phase propagation is clockwise, mainly due to the propagation direction
of the large amplitude part of the incoming semi-diurnal tidal wave from the South China Sea. A simplified basin model with
bottom slope and Coriolis force well reproduces the co-tidal and co-range charts of M2 tide in the Gulf of Thailand. 相似文献
84.
Kalmychkov G. V. Hachikubo A. Pokrovsky B. G. Minami H. Yamashita S. Khlystov O. M. 《Lithology and Mineral Resources》2020,55(6):439-444
Lithology and Mineral Resources - We studied the composition and isotopic characteristics (δ13C and δD) of hydrocarbon gases from the Kotelnikovsky, Zmeiny, and Goryachnisky hot springs... 相似文献
85.
Masayuki Mac Takahashi Kazunori Yamashita 《中国海洋大学学报(英文版)》2005,4(3):219-223
For the supply of fish and shellfish to consumers in fresh condition, clean handling after catch from the sea is essential. According to HACCP (Hazard Analysis and Critical Control Points), it is important to meet such requirement by keeping fish and shellfish under a certain low temperature and clean conditions after catching. The deep ocean water (DOW) characterized by low temperature and cleanliness has been chosen for fish and shellfish handlings, particularly for salmon, cod, and sea urchin in Town 'Rausu' in Hokkaido, Japan. DOW below 2.9℃ of an amount of nearly 5 000 m^3 is planned to be pumped up every day from a depth of about 350 m, and temporarily stored in a large simulated tank on land. DOW is then supplied to fish boats through hydrants distributed throughout the harbor and used for keeping salmon in clean and cold conditions. Ice made from DOW is also used for lowering temperature if necessary. DOW and ice made from DOW are also used during the transportation of fish and shellfish. The entire system is scheduled to be completed by the summer of 2005. 相似文献
86.
We have determined the dominant global modes of stellar discs by integrating the linearized collisionless Boltzmann equation. The models examined are the Kuzmin discs with two types of the distribution function. It is found that the growth rate correlates well with the central value ofQ.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
87.
Magnetic fluctuations observed in the magnetosheath and the outer magnetosphere with Ogo-5 during 6 months from November 1968, are analyzed to examine the resonance theory that monochromatic waves excited outside the magnetosphere are transmitted in the compressional mode into the magnetosphere, being transmitted further along the closed field lines in the torsional mode and are finally observed as long-period pcs on the Earth's surface. Ten observed results on the wave characteristics of the fluctuations including variance, spectrum, relation to the plasma stream, integrated power, longitudinal dependence are obtained and summarized. The fluctuations in the magnetosheath are found to be dominantly Alfvénic. Several pieces of evidence to support the resonance theory are found. 相似文献
88.
Though high rates of nitrate (NO3−) leaching from forests are undesirable, the factors significantly regulating stream NO3− concentration is not clarified yet. In Japan, not only near metropolitan areas but also the Japan Sea-side area with heavy snowfall is well known for receiving more than 10 kg-N ha−1 year−1 of nitrogen (N) deposition. However, NO3− concentration in stream water is relatively low in the Japan Sea-side area compared with its concentration in other areas. We examined important environmental factors regulating stream NO3− concentrations at baseflow condition in a large region of Japan, the Kinki region (KIN) including a part of Japan Sea-side (JSK) using Random Forest regression. The amounts of N deposition and precipitation were common regulating factors for stream NO3− concentration at baseflow condition. Random forest showed the significant correlation between the factors related to ecosystem N retention and stream NO3− concentration at baseflow condition, and it suggests that large N deposited during the growing season was incorporated into the ecosystem in the entire KIN. Heavy rain and snow flush N and wash out N accumulated in the surface soil, causing small N accumulation in forests. Also, large precipitation dilute NO3− concentration in baseflows. These things lowered stream NO3− concentration at baseflow condition. Especially in JSK, most of N deposed with the heavy snow flushed out during the snowmelt period. We provided the first statistical confirmation using Random Forest regression that N accumulation and cycling in forest ecosystems were related to NO3− leaching from forests into streams. 相似文献
89.
Hiromi Yamashita 《Ocean & Coastal Management》2009,52(7):327-335
Developments in coastal regions often entail invisible, complex and uncertain aspects of risk. This paper examines: (1) what kinds of environmental risk information are generally “invisible” or difficult to understand; (2) whether or not there is specific “invisible” risk information especially related to coastal development; and (3) what would be bases of risk education in coastal communities in the future. It discusses these by looking at successful and unsuccessful attempts to make some “invisible” risk information visible, using examples from Japan and elsewhere. 相似文献
90.
Napakhwan Whanpetch Masahiro Nakaoka Hiroshi Mukai Takao Suzuki Satoshi Nojima Takashi Kawai Chittima Aryuthaka 《Estuarine, Coastal and Shelf Science》2010
Seagrass beds are susceptible to various natural and human-induced disturbances. Disturbances affect not only seagrasses, but also the abundance and diversity of associated macrofaunal communities. The Andaman Sea coast of Thailand was heavily affected by the tsunami of December 26, 2004. To examine its impact on seagrass macrofaunal communities, we compared the abundance, diversity and taxa composition by quantitative samplings in 2001 (before the tsunami) and in 2005 and 2006 (after the tsunami). Macrobenthic animals and sediments were collected from vegetated and nonvegetated areas of two sites that had received different levels of tsunami disturbances. A large decline in abundance and diversity was observed in the nonvegetated areas after the tsunami, whereas an increase was observed in the vegetated areas. The magnitude of decline and subsequent recovery of abundance and diversity of macrobenthic animals in nonvegetated areas were similar between the two sites, suggesting that their temporal changes were not solely related to the magnitude of the tsunami disturbance. Similarity of the benthic animals differed greatly between 2001 and 2005–2006 at the nonvegetated areas, whereas it varied less among the 3 years at the seagrass-vegetated areas. This study demonstrated that the presence of seagrass vegetation alters the patterns of temporal variation in macrofaunal assemblages and subsequent recovery processes following a tsunami. 相似文献