全文获取类型
收费全文 | 120篇 |
免费 | 1篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 8篇 |
地球物理 | 29篇 |
地质学 | 37篇 |
海洋学 | 8篇 |
天文学 | 26篇 |
综合类 | 4篇 |
自然地理 | 7篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2011年 | 5篇 |
2010年 | 9篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 8篇 |
2005年 | 2篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1981年 | 3篇 |
排序方式: 共有121条查询结果,搜索用时 31 毫秒
81.
Yuko Ogata Kaoruko Mizukawa Satoru Iwasa Yukie Mato Keiji Okuda Michio Murakami Ruchaya Booyatumanondo Le Quang Dung Carlos Miguez Charles Moore Steven Weerts Erick Burres Michael Van Velkenburg Richard C. Lang Brenda Danner Richard C. Thompson 《Marine pollution bulletin》2009,58(10):1437-1446
Samples of polyethylene pellets were collected at 30 beaches from 17 countries and analyzed for organochlorine compounds. PCB concentrations in the pellets were highest on US coasts, followed by western Europe and Japan, and were lower in tropical Asia, southern Africa and Australia. This spatial pattern reflected regional differences in the usage of PCBs and was positively correlated with data from Mussel Watch, another monitoring approach. DDTs showed high concentrations on the US west coast and in Vietnam. In Vietnam, DDT was predominant over its metabolites (DDE and DDD), suggesting the principal source may be current usage of the pesticide for malaria control. High concentrations of pesticide HCHs were detected in the pellets from southern Africa, suggesting current usage of the pesticides in southern Africa. This study demonstrates the utility and feasibility of the International Pellet Watch approach to monitor POPs at a global scale. 相似文献
82.
A high-resolution pollen record covering the last 40,000 yr (BIW95-4) from Lake Biwa, western Japan, shows regional vegetation responses to millennial-scale climate changes. From 40 to 30 ka, Cryptomeria japonica was dominant around the lake among pinaceous conifers and deciduous broad-leaved trees. During this period, fluctuations of C.japonica are correlated with Dansgaard-Oeschger (D-O) cycles recognized from the anhysteretic remanent magnetization (ARM) record. Increases in the abundance of this taxon may have been caused by wetter summer conditions influenced by the East Asian monsoon or increased snowfall on the Sea of Japan side of the Japanese archipelago. Between 29 and 14 ka, pinaceous conifer forests mainly composed of Pinus subgenus Haploxylon, Tsuga, and Picea trees developed. At approximately 23 ka, Picea trees increased in abundance as ARM values decreased. This expansion of Picea trees has been correlated with Heinrich event (HE) 2 in the North Atlantic. At about 14 ka, the distribution of broad-leaved forest (mainly composed of deciduous oaks) began to expand after D-O 1. Evidence of significant vegetation change related to the abrupt Younger Dryas cooling event has not been found. 相似文献
83.
A fundamental mechanism on the atomic level for self-diffusion in the proton layer of portlandite, Ca(OH)2, was investigated by conducting hydrogen–deuterium (H–D) exchange diffusion experiments and by deriving potential energy
curves of OH vibrations from optical absorption measurements. Synthetic single crystals of portlandite were used in H–D experiments
between 250 and 450°C at 150 MPa. Arrhenius parameters for proton diffusion perpendicular to the c-axis gave a frequency factor of 1.0 × 10−10 m2/s and activation energy of 0.61 eV (58.5 kJ/mol). The activation energy corresponds to the height of the potential barrier
between two oxygen atoms across an interlayer. The potential barrier height was also theoretically estimated using the OH
potential energy curve (OH-PEC) determined by optical absorption measurements. Experimental and theoretical results suggest
that the potential barrier height cannot be simply determined by overlapping two OH-PECs. The potential barrier derived theoretically
was 3.11 eV. This is too high for the activation energy of the proton diffusion. It implies that the interaction between a
diffusing proton and the vacancy of a proton site, and the shortening of interlayer oxygen distance by thermal vibration reduce
the potential barrier. 相似文献
84.
Tomoki Nakaya A. Stewart Fotheringham Kazumasa Hanaoka Graham Clarke Dimitris Ballas Keiji Yano 《Journal of Geographical Systems》2007,9(4):345-369
Although the disaggregation of consumers is crucial in understanding the fragmented markets that are dominant in many developed
countries, it is not always straightforward to carry out such disaggregation within conventional retail modelling frameworks
due to the limitations of data. In particular, consumer grouping based on sampled data is not assured to link with the other
statistics that are vital in estimating sampling biases and missing variables in the sampling survey. To overcome this difficulty,
we propose a useful combination of spatial interaction modelling and microsimulation approaches for the reliable estimation
of retail interactions based on a sample survey of consumer behaviour being linked with other areal statistics. We demonstrate
this approach by building an operational retail interaction model to estimate expenditure flows from households to retail
stores in a local city in Japan, Kusatsu City.
相似文献
85.
Concentration of polychlorinated biphenyls (PCBs) in beached resin pellets: variability among individual particles and regional differences 总被引:1,自引:0,他引:1
Endo S Takizawa R Okuda K Takada H Chiba K Kanehiro H Ogi H Yamashita R Date T 《Marine pollution bulletin》2005,50(10):1103-1114
Concentrations of polychlorinated biphenyls (PCBs) in beached resin pellets were examined to reveal variability between individual particles and differences among beaches. Fifty-five resin pellets from a beach in Tokyo were individually analyzed for PCBs, and showed concentrations ranging from <28 to 2,300 ng/g. This indicates that concentrations are highly variable between particles. Among several characters, discoloration (e.g., yellowing) had a positive relationship with PCB concentration: discolored pellets contained more PCBs than others on most of the beaches sampled. Given the color-selective ingestion of food by some organisms, this may be ecotoxicologically important. Measurements of samples from 47 beaches in Japan showed regional differences in PCB concentrations in resin pellets consistent with those in mussels. Sporadic high concentrations of PCBs were also found in pellets from remote islands, suggesting that resin pellets could be the dominant route of exposure to the contaminants at remote sites. The similarity of PCB concentrations between resin pellets and mussels suggests a potential use of resin pellets to monitor pollution in seawater. 相似文献
86.
The shape and intensity distribution of tails for several large comets are estimated on the basis of grain properties in the solar radiation field. The following results are obtained: (1) The ratio of the maximum radiation pressure force to the gravitaional force acting on dust grains in cometary tails is found to be less than 2.5. This means that grains such as graphite particles in the size range 0.02–0.2 μm do not exist in them, because such particles would allow forces greater than 2.5 (2) Tail substances supplied near the time of perihelion passage for the Sun-grazing comet Ikeya-Seki (1965 VIII) and Comet Seki-Lines (1962 III) were composed of particular grains which had values of radiation pressure ratio less than 1.0. Therefore, it is concluded that the material was composed of silicate grains only, since iron grains had sublimated and there were no graphite particles. 相似文献
87.
Comparative study of cataclastic rocks from a drill core and outcrops of the Nojima Fault zone on Awaji Island, Japan 总被引:3,自引:0,他引:3
88.
Hidemi Tanaka Shin-Ichiro Hinoki Kazuo Kosaka Aiming Lin Keiji Takemura Akihiro Murata Takao Miyata 《Island Arc》2001,10(3-4):381-391
Abstract This paper describes the results of petrographical and meso- to microstructural observations of brittle fault rocks in cores obtained by drilling through the Nojima Fault at a drilling depth of 389.52 m. The zonation of deformation and alteration in the central zone of the fault is clearly seen in cores of granite from the hanging wall, in the following order: (i) host rock, which is characterized by some intragranular microcracks and in situ alteration of mafic minerals and feldspars; (ii) weakly deformed and altered rocks, which are characterized by transgranular cracks and the dissolution of mafic minerals, and by the precipitation of zeolites and iron hydroxide materials; (iii) random fabric fault breccia, which is characterized by fragmentation, by anastomosing networks of transgranular cracks, and by the precipitation of zeolites and iron hydroxide materials; and (iv) fault gouge, which is characterized by the precipitation of smectite and localized cataclastic flow. This zonation implies that the fault has been weakened gradually by fluid-related fracturing over time. In the footwall, a gouge layer measuring only 15 mm thick is present just below the surface of the Nojima Fault. These observations are the basis for a model of fluid behavior along the Nojima Fault. The model invokes the percolation of meteoric fluids through cracks in the hanging wall fault zone during interseismic periods, resulting in chemical reactions in the fault gouge layer to form smectite. The low permeability clay-rich gouge layer sealed the footwall. The fault gouge was brecciated during coseismic or postseismic periods, breaking the seal and allowing fluids to readily flow into the footwall, thus causing a slight alteration. Chemical reactions between fluids and the fault breccia and gouge generated new fault gouge, which resealed the footwall, resulting in a low fluid condition in the footwall during interseismic periods. 相似文献
89.
Takaya Iwasaki Keiji Adachi Takeo Moriya Hiroki Miyamachi Takeshi Matsushima Kaoru Miyashita Testsuya Takeda Takaaki Taira Tomoaki Yamada Kazuo Ohtake 《Tectonophysics》2004,388(1-4):59
The Hidaka Collision Zone (HCZ), central Hokkaido, Japan, is a good target for studies of crustal evolution and deformation processes associated with an arc–arc collision. The collision of the Kuril Arc (KA) with the Northeast Japan Arc (NJA), which started in the middle Miocene, is considered to be a controlling factor for the formation of the Hidaka Mountains, the westward obduction of middle/lower crustal rocks of the KA (the Hidaka Metamorphic Belt (HMB)) and the development of the foreland fold-and-thrust belt on the NJA side. The “Hokkaido Transect” project undertaken from 1998 to 2000 was a multidisciplinary effort intended to reveal structural heterogeneity across this collision zone by integrated geophysical/geological research including seismic refraction/reflection surveys and earthquake observations. An E–W trending 227 km-long refraction/wide-angle reflection profile found a complicated structural variation from the KA to the NJA across the HCZ. In the east of the HCZ, the hinterland region is covered with 4–4.5 km thick highly undulated Neogene sedimentary layers, beneath which two eastward dipping reflectors were imaged in a depth range of 10–25 km, probably representing the layer boundaries of the obducting middle/lower crust of the KA. The HMB crops out on the westward extension of these reflectors with relatively high Vp (>6.0 km/s) and Vp/Vs (>1.80) consistent with middle/lower crustal rocks. Beneath these reflectors, more flat and westward dipping reflector sequences are situated at the 25–27 km depth, forming a wedge-like geometry. This distribution pattern indicates that the KA crust has been delaminated into more than two segments under our profile. In the western part of the transect, the structure of the fold-and-thrust belt is characterized by a very thick (5–8 km) sedimentary package with a velocity of 2.5–4.8 km/s. This package exhibits one or two velocity reversals in Paleogene sedimentary layers, probably formed by imbrication associated with the collision process. From the horizontal distribution of these velocity reversals and other geophysical/geological data, the rate of crustal shortening in this area is estimated to be greater than 3–4 mm/year, which corresponds to 40–50% of the total convergence rate between the NJA and the Eurasian Plate. This means that the fold-and-thrust belt west of the HCZ is absorbing a large amount of crustal deformation associated with plate interaction across Hokkaido Island. 相似文献
90.
Mineral parageneses and metamorphic P-T paths of ultrahigh-pressure eclogites from Kyrghyzstan Tien-Shan 总被引:3,自引:0,他引:3
Abstract Eclogites occur in three districts of the northern and southern parts of Tien-Shan. Three eclogites collected from the Aktyuz, Makbal and Atbashy districts were analyzed; the P-T paths of three eclogites were estimated by analyzing compositional growth zoning and retrograde reaction of garnet and omphacite. Aktyuz and Makbal eclogites have not preserved the prograde path. An Aktyuz eclogite that underwent a quartz eclogite facies metamorphism (about T = 600°C, P = 12 kbar) has recorded three stages of retrograde metamorphism. Four stages of retrograde metamorphism were recognized in a Makbal eclogite; the garnet-omphacite geothermometer gave about T = 560°C at 20 kbar as the highest metamorphic condition. Garnet from a garnetchloritoid-talc schist of the Makbal district includes quartz pseudomorphs after coesite; some units evidently underwent a low-temperature part of coesite eclogite fades metamorphism. Prograde and retrograde paths were recognized in an Atbashy eclogite; five stages of metamorphic reaction were observed in the Atbashy sample. The prograde path from stage I to stage III has been recorded in garnet and omphacite in which quartz pseudomorphs after coesite are included. The peak metamorphism of stage III took place at about 660°C at 25 kbar. The stages IV and V are retrograde. UHP eclogite facies metamorphism took place twice in Kyrghyzstan. The Aktyuz and Atbashy eclogites gave Rb-Sr mineral-isochron ages of about 750 Ma and 270 Ma, respectively. The K-Ar age of paragonite from the Makbal eclogite is about 480 Ma. 相似文献