全文获取类型
收费全文 | 230篇 |
免费 | 10篇 |
国内免费 | 5篇 |
专业分类
大气科学 | 3篇 |
地球物理 | 61篇 |
地质学 | 68篇 |
海洋学 | 66篇 |
天文学 | 25篇 |
综合类 | 2篇 |
自然地理 | 20篇 |
出版年
2024年 | 1篇 |
2021年 | 4篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 10篇 |
2016年 | 8篇 |
2015年 | 13篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 13篇 |
2011年 | 21篇 |
2010年 | 16篇 |
2009年 | 11篇 |
2008年 | 13篇 |
2007年 | 9篇 |
2006年 | 11篇 |
2005年 | 13篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 1篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有245条查询结果,搜索用时 250 毫秒
201.
This study investigated the desorption behavior of polychlorinated biphenyls (PCBs) from marine plastic pellets. Long-term desorption experiments were conducted using field-collected polyethylene (PE) pellets. The results indicate that the desorption kinetics highly depends on the PE-water partition coefficients of PCB congeners. After 128 d of the experiment, the smallest congener considered (CB 8) had desorbed nearly completely (98%), whereas major fractions (90–99%) of highly chlorinated congeners remained in the pellets. An intraparticle diffusion model mostly failed to reproduce the desorption kinetics, whereas an aqueous boundary layer (ABL) diffusion model well approximated the data. The desorption half-lives are estimated to 14 d to 210 years for CB 8 to CB 209 in an actively stirred solution (ABL thickness: 30 μm). Addition of methanol to water enhanced the desorption to a large extent. A need for further work to explore roles of organic matter in facilitating solute transfer is suggested. 相似文献
202.
A framework for economic loss estimation due to seismic transportation network disruption: a spatial computable general equilibrium approach 总被引:4,自引:4,他引:0
This paper presents a framework for assessing the economic impact of disruption in transportation that can relate the physical
damage to transportation networks to economic losses. A spatial computable general equilibrium (SCGE) model is formulated
and then integrated with a transportation model that can estimate the traffic volumes of freight and passengers. Economic
equilibrium under a disruption in the transportation network is computed subject to the condition that the adjustment of labor
and capital inputs is restricted; the model reflects slow adjustment of these linked to the state of recovery. As a case study,
the model reviews the large Niigata-Chuetsu earthquake of 2004. Considering the damage to the transportation infrastructure,
the model indicates the extent of the economic losses arising from the earthquake distributed over regions as a consequence
of the intra- and interregional trade in a regional economy. The results show that 20% of the indirect losses occur in the
Niigata region directly affected by the earthquake, whereas 40% of the total losses are experienced in the Kanto region and
non-negligible losses reach rather remote zones of the country such as Okinawa. 相似文献
203.
Towhata Ikuo Goto Satoshi Goto Shigeru Akima Takeshi Tanaka Junya Uchimura Taro Wang Gonghui Yamaguchi Hiroshi Aoyama Shogo 《Natural Hazards》2021,105(1):501-530
Natural Hazards - A volcanic slope in Izu Oshima Island in Japan experienced a profound rain-induced disaster in October 2013. Since this slope had been stable for centuries except for minor... 相似文献
204.
As planetary embryos grow, gravitational stirring of planetesimals by embryos strongly enhances random velocities of planetesimals and makes collisions between planetesimals destructive. The resulting fragments are ground down by successive collisions. Eventually the smallest fragments are removed by the inward drift due to gas drag. Therefore, the collisional disruption depletes the planetesimal disk and inhibits embryo growth. We provide analytical formulae for the final masses of planetary embryos, taking into account planetesimal depletion due to collisional disruption. Furthermore, we perform the statistical simulations for embryo growth (which excellently reproduce results of direct N-body simulations if disruption is neglected). These analytical formulae are consistent with the outcome of our statistical simulations. Our results indicate that the final embryo mass at several AU in the minimum-mass solar nebula can reach about ∼0.1 Earth mass within 107 years. This brings another difficulty in formation of gas giant planets, which requires cores with ∼10 Earth masses for gas accretion. However, if the nebular disk is 10 times more massive than the minimum-mass solar nebula and the initial planetesimal size is larger than 100 km, as suggested by some models of planetesimal formation, the final embryo mass reaches about 10 Earth masses at 3-4 AU. The enhancement of embryos’ collisional cross sections by their atmosphere could further increase their final mass to form gas giant planets at 5-10 AU in the Solar System. 相似文献
205.
Seaports are located in vulnerable areas to climate change impacts: on coasts susceptible to sea-level rise and storms or at mouths of rivers susceptible to flooding. They serve a vital function within the local, regional, and global economy. Their locations in the heart of sensitive estuarine environments make it an imperative to minimize the impacts of natural hazards. Climate impacts, like a projected SLR of .6?m to 2?m and doubling of Category 4 and 5 hurricanes by 2100, will result in more extreme events at many seaports. To assess the current state of knowledge on this issue, we surveyed port authorities from around the world about how administrators felt climate change might impact their operations, what sea-level change would create operational problems, and how they planned to adapt to new environmental conditions. The planned rapid expansion of ports reported by the survey respondents indicates that adaptation measures should be considered as ports construct new infrastructure that may still be in use at the end of the century. Respondents agreed that the ports community needs to address this issue and most felt relatively uninformed about potential climate impacts. Although most ports felt that SLR would not be an issue at their port this century, sea-level rise was nevertheless an issue of great concern. Our results suggest opportunities for the scientific community to engage with port practitioners to prepare proactively for climate change impacts on this sector. 相似文献
206.
Plankton samples from the Chatham Rise, Pukaki Rise, and Campbell Plateau provided information on the young stages of a number of poorly known New Zealand fish species, and on the presence of a large spawning area of barracouta, Thyrsites atun, over the Mernoo Bank, The Chatham Rise was more important as a spawning area than the areas further south. 相似文献
207.
The Soft X-ray Telescope (SXT) onboard Yohkoh often observed large-scale coronal loops connecting two active regions situated in opposite hemispheres. These are the trans-equatorial
loop systems (TLSs). The formation mechanism of TLSs is not yet known. We analyzed a TLS observed simultaneously with Yohkoh/SXT and a coronagraph (SOHO/LASCO-C1). SOHO/LASCO-C1 observed loop expansion and eruption at the west solar limb. Yohkoh/SXT observed a rising motion (chromospheric evaporation) of hot and dense plasmas from the active regions located at the
footpoints of the loop. Important results of our analyses are that (1) the loop eruption and the rising motion of the plasmas
were simultaneous, (2) the TLS had a cusp-like appearance, and (3) the highest temperature region of the TLS was located above
the bright loop seen in soft X rays. These observational results (loop expansion, eruption, and chromospheric evaporation)
suggest that this bright (high-density) TLS was created by the same mechanism by which a solar flare occurs, namely, magnetic
reconnection. In this paper, we propose a formation mechanism of the TLS that forms between two independent active regions. 相似文献
208.
209.
Xu Wenjun Zhao Weiming Chai Chizhang Jin Yanlong Sun Lixin Zheng Sihu Satoshi Miura 《中国地震研究》2001,15(3):252-265
INT正ODU**!0厂Nln以la Is located In the nol’th segmentdthe North-southselsnuc Belt,Whlchls thejuncturedthe Qinghai-Xizang(Dbet)block,Alxa block and Odos block.In that region,the tectonic activity。svery strong;。y strong earthquakes occu。d In history,such as the 1739 ingluo M。8.0 earthqu拙eandl920 Halyuan M。8.5 eafthquake,etc.; Merately strongeaFthquakes are still veryactlve atpresent,onlyln the Wuzhong-un斟m area,there have been7 e血hquakes tvlth M。>5.0 to occ… 相似文献
210.
Satoshi Hinata 《Solar physics》1982,80(1):173-183
Current dissipation models of coronal loop heating are studied. Turbulent current dissipation is shown to lead to a time dependent process because of an enormous mass motion induced in the current layer. A stationary heating process involves only ohmic heating, which requires a large current layer. To insure MHD stability, the loop must be composed of many elements with the oppositely directed currents. A stationary current dissipation process induces the plasma motion across the magnetic field into the loop and down the loop with the speeds v
104 cm s–1 and v
104 cm s–1, respectively. The pressure of the loop is also estimated to be proportional to the current density: p/J=6.3 × 10-8dyn/statamp. 相似文献