全文获取类型
收费全文 | 433篇 |
免费 | 9篇 |
国内免费 | 7篇 |
专业分类
测绘学 | 6篇 |
大气科学 | 29篇 |
地球物理 | 133篇 |
地质学 | 124篇 |
海洋学 | 88篇 |
天文学 | 32篇 |
综合类 | 3篇 |
自然地理 | 34篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 27篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 27篇 |
2009年 | 24篇 |
2008年 | 32篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 23篇 |
2004年 | 18篇 |
2003年 | 16篇 |
2002年 | 15篇 |
2001年 | 19篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1956年 | 2篇 |
1953年 | 1篇 |
1951年 | 1篇 |
1950年 | 2篇 |
排序方式: 共有449条查询结果,搜索用时 31 毫秒
311.
A large number of tar globules with sessile organisms were collected from the surface tows taken with larval nets in the waters around the Ryukyu Islands during November and December, 1973. Bryozoans (one species), tubeworms (Serpulidae,Janua (Dexiospira) foraminosa (Moore &Bush)) and goose barnacles (Lepas pectinata Spengler,L. anatifera Linné) were the most important species of sessile animals found on these tar globules. Sinking of tar globules byLepas of middle or large size was suggested from the differences in their specific gravity. 相似文献
312.
The effect of the earth's rotation on the behavior of heated water discharged from gigantic nuclear power plants was investigated numerically. It is shown that the effect is significant even for the existing scale of discharge. Horizontal spreading of the heated water is suppressed in offshoreward and northward directions (when heated water is discharged in an eastward direction from a westfacing coast in the northern hemisphere), but accelerated in the southward direction, and the shape of the formed warm water region becomes asymmetric. In this paper, several calculations were done using exaggerated Coriolis parameters (f) in order to demonstrate the effect of the earth's rotation. An increase off enhances above effect, but the situation of the inner region of the produced warm water mass is much different from that in the outer region near its margin. The southward expansion of surface isothermal contours in the inner region increases with an increase inf, but those in the outer region do not. This results in an increase of the sharpness of the front which is generated near the southern edge of the warm water region. We have not found simple parameters which describe the temperature and velocity distributions in the warm water mass produced. 相似文献
313.
Takeshi Naganuma Mutsuo Hattori Kazumi Akimoto Jun Hashimoto Hiroyasu Momma & C. Julius Meisel 《Marine Ecology》2001,22(3):267-282
Abstract. Abyssal microfloral succession induced by experimental organic degradation was investigated. Notable changes in amounts and compositions of short-chain (C9-20) sediment fatty acids were observed, which indicated the shift of sediment microflora. Biomarker fatty acids for methanotrophs and sulfate-reducing bacteria dominated. Resultant fatty acid compositions were most closely related to those from a nearby methane seep harboring a dense Calyptogena colony; the clams were also seen in close vicinity of the deployed organic mass. These observations suggest that the organic degradation on the bathyal seafloor stimulates the formation of methanotrophic and thiotrophic microflora, resulting in the formation of a methane-seep-type benthic community. 相似文献
314.
315.
Takeshi Nakatsuka Nobuhiko Handa Naomi Harada Tatsuhiro Sugimoto Shigemi Imaizumi 《Deep Sea Research Part I: Oceanographic Research Papers》1997,44(12):1957-1979
Sinking particles were analyzed for their nitrogen isotopic ratio δ15N) of total particulate nitrogen (PN), stable carbon isotopic ratio (δ13C) and radioactive isotopic ratio (δ14C) of total particulate organic carbon (POC), at three different latitudinal (temperate, subpolar and equatorial) and geomorphological (trench, proximal abyssal plain and distal abyssal plain) sites in the western North Pacific Ocean using year-long time series sediment trap systems, to clarify the common vertical trends of the isotopic signals in deep water columns. Although the δ15N and δ13C values of sinking particulate organic matter (POM) were partly affected by the resuspension of sedimentary POM from the sea floor, especially in the trench, the changes in δ15N and δ13C values owing to the resuspension could be corrected by calculation of the isotopic mass balance from δ14C of sinking POC. After this correction, common downward decreasing trends in δ15N and δ13C values were obtained in the deep water columns, irrespective of the latitudes and depths. These coincidental isotopic signals between δ15N and δ13C values provide new constraints for the decomposition process of sinking POM, such as the preferential degradation of 15N- and 13C-rich compounds and the successive re-formation of the sinking particles by higher trophic level organisms in the deep water column. 相似文献
316.
Abundance and productivity of bacterioplankton in a eutrophication gradient of Shimoda Bay 总被引:1,自引:0,他引:1
Abundance, specific growth rate, and productivity of bacterioplankton were investigated over a year in Shimoda Bay, Japan, with reference to the eutrophication parameters such as dissolved organic carbon (DOC) concentration. The results from six stations in the bay indicated the formation of a eutrophic gradient ranging from eutrophic (at a river mouth) to mesotrophic (at the bay mouth) levels. Both DOC concentration and UV absorbance were found to have good correlations to bacterioplankton abundance and productivity within the eutrophication range of Shimoda Bay. 相似文献
317.
Takeshi Kawano Michio Aoyama Terry Joyce Hiroshi Uchida Yasushi Takatsuki Masao Fukasawa 《Journal of Oceanography》2006,62(6):777-792
An updated batch-to-batch difference table of IAPSO standard seawater (SSW) up to P145 is proposed. The batch-to-batch difference
table is based on several recent SSW comparison experiments, including the experiments conducted independently at the Japan
Agency for Marine-Earth Science and Technology (JAMSTEC) and Woods Hole Institute of Oceanography (WHOI) at about the same
time using the same procedure. Proposed batch-to-batch differences range from 1.2 × 10−3 to −1.9 × 10−3 with reference to the average of those from P91 to P102. Batch-to-batch differences from P29 to P145 with reference to the
recent batches and this average over every 5 years since 1960 are also presented, together with standard deviation. This reveals
that inconsistency among batches has improved since 1980s. In particular, the standard deviation was 0.3 × 10−3 in this decade, which is about one-half the value reported previously and almost equal to the modern measurement precision
(0.2 × 10−3) and is within-batch difference (<0.3 × 10−3). Proposed batch-to-batch differences were applied to the observational results of the WOCE hydrographic onetime section
(WHP onetime) in the Indian Ocean. Average absolute salinity differences at 14 crossover points in the Indian Ocean were slightly
larger, from 1.2 × 10−3 to 1.5 × 10−3, when the batch-to-batch difference table was applied; however, when results from the Indian, Pacific, and Atlantic Oceans
were combined, application of the batch-to-batch difference table yielded statistically acceptable salinity differences. The
table was also applied to WHP sections P1 and P17 (revisited about 10 years after the original observations during the WOCE
period) and sections I1, I7, and I8 (visited twice by different research vessels in the same year). In all cases, the table
corrected unrealistically large salinity changes in space and time. The results suggest that the application of the batch-to-batch
table to well-controlled salinity data such as WOCE datasets would be effective in making the datasets more consistent in
space and time. 相似文献
318.
Effect of iron enrichment on the dynamics of transparent exopolymer particles in the western subarctic Pacific 总被引:1,自引:0,他引:1
Neelam Ramaiah Shigenobu Takeda Ken Furuya Takeshi Yoshimura Jun Nishioka Tatsuo Aono Yukihiro Nojiri Keiri Imai Isao Kudo Hiroaki Saito Atsushi Tsuda 《Progress in Oceanography》2005,64(2-4):253
Dynamics of transparent exopolymer particles (TEP) was studied during the first in situ iron-enrichment experiment conducted in the western subarctic Pacific in July–August 2001, with the goal of evaluating the contribution of TEP to vertical flux as a result of increased primary production following iron enrichment in open ocean ecosystems. Subsequent to the enhancement of phytoplankton production, we observed increase in TEP concentration in the surface layer and sedimentation of organic matter beneath it. Vertical profiles of TEP, chlorophyll a (Chl a) and particulate organic carbon (POC) were obtained from six depths between 5 and 70 m, from a station each located inside and outside the enriched patch. TEP and total mass flux were estimated from the floating sediment traps deployed at 200 m depth. Chl a and TEP concentrations outside the patch varied from 0.2 to 1.9 μg L−1 and 40–60 μg XG equiv. L−1, respectively. Inside the patch, Chl a increased drastically from day 7 reaching the peak of 19.2 μg L−1 on day 13, which coincided with the TEP peak of 189 μg XG equiv. L−1. TEP flux in the sediment trap increased from 41 to 88 mg XG equiv. m−2 d−1, with 8–14% contribution of TEP to total mass flux. This forms the basic data set on ambient concentrations of TEP in the western subarctic Pacific, and evaluation of the effect of iron enrichment on TEP. 相似文献
319.
Measurements of the Turbulent Energy Dissipation Rate around the Shelf Break in the East China Sea 总被引:1,自引:0,他引:1
Takeshi?MatsunoEmail author Manabu?Shimizu Yasuhiro?Morii Hideaki?Nishida Yasuaki?Takaki 《Journal of Oceanography》2005,61(6):1029-1037
Using the micro-structure profiler, TurboMAP, large values for the turbulent energy dissipation rate ε were found just above the bottom of the shelf and around the thermocline near the continental shelf break in the East China
Sea. The values found above the bottom are produced by the bottom stress due to tidal currents, resulting in a distinct bottom
mixed layer where the vertical eddy diffusivity Kz is also large. Distinct maxima in the values of ε detected around the thermocline are located at the depth of the fine-scale shear maxima detected with the moored ADCP. The
vertical profiles of ε were compared with those of the current velocity, and it was found that the maxima in ε appear to correspond to those of the shear with fine scale. The magnitude of the observed ε coincided approximately with the ε calculated from the fine-scale shear and the buoyancy frequency according to the parameterization proposed by Gregg (1989),
if the large-scale mean shear caused by the Kuroshio is subtracted. However, it is not clear whether the parameterization
for the internal wave fields in the open ocean is applicable to the estimation of ε in the shelf break. Whereas the most predominant value of ε was found just above the bottom and around the thermocline, the maxima of ε could be found in the internal area. They could have been caused by the propagation of the vertically high wave number internal
tides along the characteristic ray. 相似文献
320.
Toshiyuki Masuzawa Tie LiYun Duan Mineko YamamotoYuriko Hibi Takeshi NakatsukaHiroshi Kitazato Yoshihisa Kato 《Progress in Oceanography》2003,57(1):59-75
Sinking particles were collected using time-series sediment traps deployed at 350 and 20 mab at Site SB (34° 58.5’N, 139° 20.9’E, 1544 m depth) near the center of Sagami Bay, off Japan with high time resolutions of 5-8 days (March 1997 to August 1998) and 3-4.5 days (March 1998 to August 1998), respectively. The major components (CaCO3, OM, opal, and clay) of these sinking particles and surface bottom sediments were determined using a stepwise leaching method combined with gravimetry. Average total mass fluxes were 1480, 5560 and 3068 mg/m2/year at 350 mab, at 20 mab, and in the surface sediments, respectively, indicating an enhanced collection of sinking particles at 20 mab. Clay was the dominant component and biogenic components (opal+OM+CaCO3) were dominated mainly by opal and secondly by OM. On average, opal and CaCO3 contents decreased gradually as clay content increased with increasing depth from 350 mab-20 mab and in the surface sediments, indicating dissolution of opal and CaCO3 through sinking, rebound, resuspension or sedimentation processes. Thirteen total mass flux peaks at 17--40-day intervals were observed at 350 mab during the period from March 1997 to August 1998 except for winter, while eight peaks were observed at 20 mab for the period from March 1998 to August 1998. Two types of total mass peaks can be distinguished: one with a clear increase in biogenic flux (opal+OM+CaCO3) and little or no increase in clay flux and termed a bloom type (B-type), and the other with a clear increase in clay flux, little increase in biogenic flux and termed a resuspension type (R-type). Some R-type peaks, but not all, coincided with total mass flux peaks observed at the mouth of Tokyo Bay and suggested the possibility of the effect of particulate materials transported from Tokyo Bay to site SB. The enormously large peak observed at 20 mab in late May 1998 and that at 350 mab in early June 1998 were considered to be due to some physical perturbations from an earthquake swarm near site SB during the period from April to June 1998. The 17--40-day periodicity was associated clearly with the change in biogenic flux dominated by opal flux and is thought to reflect the periodicity of biological productivity dominated by diatoms in the euphotic zone of Sagami Bay. 相似文献