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101.
圆尾斗鱼的胚胎和仔鱼发育的研究 总被引:7,自引:0,他引:7
圆尾斗鱼的受精卵呈圆球形,光滑,略带淡黄色,浮性;卵膜吸水膨胀后的平均直径为1.19mm,当水温21-23.5℃时,从受精卵到孵化出膜需42.5小时;水温22-24.5℃时,刚出膜仔鱼到卵黄囊消失需4天,到油球消失约25天。出膜30天仔鱼的形态基本与成体相似。 相似文献
102.
Jérôme Harlay Caroline De Bodt Anja Engel Sandra Jansen Quentin d’Hoop Judith Piontek Nicolas Van Oostende Steve Groom Koen Sabbe Lei Chou 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(8):1251-1265
The distribution of transparent exopolymer particles (TEP) was investigated during a coccolithophorid bloom in the northern Bay of Biscay (North Atlantic Ocean) in early June 2006. MODIS chlorophyll-a (Chl-a) and reflectance images before and during the cruise were used to localize areas of important biological activity and high reflectance (HR). TEP profiles along the continental margin, determined using microscopic (TEPmicro) and colorimetric (TEPcolor) methods, showed abundant (6.1×106–4.4×107 L?1) and relatively small (0.5–20 μm) particles, leading to a low total volume fraction (0.05–2.2 ppm) of TEPmicro and similar vertical profiles of TEPcolor. Estimates of carbon content in TEP (TEP-C) derived from the microscopic approach yielded surface concentration of 1.50 μmol C L?1. The contribution of TEP-C to particulate organic carbon (POC) was estimated to be 12% (molar C ratio) during this survey. Our results suggest that TEP formation is a probable first step to rapid and efficient export of C during declining coccolithophorid blooms. 相似文献
103.
We use five-day helioseimic data from the Taiwan Oscillation Network to study the flow around a sunspot, NOAA 7887. The p-mode oscillations in an annular region centered at the sunspot are decomposed into the modes propagating toward and away from the sunspot. We find that the frequency of an outgoing mode is greater than that of the corresponding incoming mode. This indicates that the plasma is flowing outward from the sunspot. The outflow velocity is estimated to be about 40–80 m s-1. 相似文献
104.
Yung-Ping Chou 《Solar physics》2001,199(2):345-369
We perform numerical simulations using an avalanche model for solar flares, in which the effect of avalanche event duration is included and the lateral boundary condition can be either open or periodic. The results from the simulations show that self-organized criticality (SOC) exists under a variety of conditions of helicity dissipation, and they are similar in the sense that the indices of power-law distributions of avalanche sizes are the same, while the duration and waiting time distributions differ little. Of interest are: (1) if there exists helicity dissipation in the course of avalanches, SOC exists only when the amount of helicity dissipation per avalanche is small; (2) sudden reductions in the total helicity of the system do not severely disturb SOC, if the amount reduced is moderate; (3) the distribution of waiting times is shown to be exponential, in consistent with the Poisson statistics other avalanche models have predicted, and the exponent increases as the effect of event duration becomes larger. The self-similar structure of the avalanche time series is also examined. These results imply that, although helicity is dissipated in resistive diffusion of flares, the amount of dissipation should be small and the conservation law of helicity thus holds in an approximate sense. Also, the coronal mass ejections (CMEs), observed to take helicity out of the solar corona in an eruptive way, may disrupt the statistical equilibrium of the corona only temporarily. 相似文献
105.
Fate of paralytic shellfish poisoning toxins in purple clam Hiatula rostrata,in outdoor culture and laboratory culture 总被引:1,自引:0,他引:1
Purple clams (Hiatula rostrata Lighttoot) accumulate paralytic shellfish poisoning (PSP) toxins produced by a toxic strain of the dinoflagellate Alexandriun minutum Halim. The results confirm the data of our previous study concerning the muscle and siphon that were not showing a gradual rise in toxicity when shellfish accumulated more A. minutum. However, muscle and siphon are intermittently toxic both in exposure and depuration period in laboratory cultured purple clams. PSP toxins were detected in outdoor cultured purple clams, whereas no A. minutum were found in the culture pond during most of the survey time. The outdoor cultured purple clams need longer time to decrease toxicity to allowable levels than laboratory cultured purple clams. It was shown that laboratory data may not predict times over which pond-cultured purple clams may prove toxic to consumers. 相似文献
106.
Wen-Chen Chou Gwo-Ching Gong Chun-Mao Tseng David D. Sheu Chin-Chang Hung Lo-Ping Chang Li-Wen Wang 《Marine Chemistry》2011,123(1-4):44-55
Measurements of dissolved inorganic carbon (DIC), pH, total alkalinity (TA), and partial pressure of CO2 (pCO2) were conducted at a total of 25 stations along four cross shelf transects in the East China Sea (ECS) in January 2008. Results showed that their distributions in the surface water corresponded well to the general circulation pattern in the ECS. Low DIC and pCO2 and high pH were found in the warm and saline Kuroshio Current water flowing northeastward along the shelf break, whereas high DIC and pCO2 and low pH were mainly observed in the cold and less saline China Coastal Current water flowing southward along the coast of Mainland China. Difference between surface water and atmospheric pCO2 (ΔpCO2), ranging from ~ 0 to ? 111 μatm, indicated that the entire ECS shelf acted as a CO2 sink during winter with an average flux of CO2 of ?13.7 ± 5.7 (mmol C m? 2 day? 1), and is consistent with previous studies. However, pCO2 was negatively correlated with temperature for surface waters lower than 20 °C, in contrast to the positive correlation found in the 1990s. Moreover, the wintertime ΔpCO2 in the inner shelf near the Changjiang River estuary has appreciably decreased since the early 1990s, suggesting a decline of CO2 sequestration capacity in this region. However, the actual causes for the observed relationship between these decadal changes and the increased eutrophication over recent decades are worth further study. 相似文献
107.
Leonardo Casini Stefano Andreucci Daniele Sechi Chun‐Yuan Huang Chuan‐Chou Shen Vincenzo Pascucci 《地学学报》2020,32(4):261-271
Precise dating of the activity of Late Pleistocene to Holocene neo‐tectonic structures is crucial to quantify the rate of deformation in low‐seismicity regions. Sardinia is a relatively stable continental fragment set in the middle of the tectonically active Western Mediterranean belt. This paper provides evidences of significant uplift of northwest Sardinia that support an ongoing tectonic activity since the Marine Isotopic Stage 7 (MIS 7; ca. 220 ka). In particular, it documents for the first time Late Pleistocene to Holocene tectonics based on luminescence dating of travertine sealing a major NNE‐SSW fault. 相似文献
108.
Analogue-dynamical prediction of monsoon precipitation in Northeast China based on dynamic and optimal configuration of multiple predictors 下载免费PDF全文
Based on the National Climate Center (NCC) of China operational seasonal prediction model results for the period 1983–2009
and the US National Weather Service Climate Prediction Center merged analysis of precipitation in the same period, together
with the 74 circulation indices of NCC Climate System Diagnostic Division and 40 climate indices of NOAA of US during 1951–2009,
an analogue-dynamical technique for objective and quantitative prediction of monsoon precipitation in Northeast China is proposed
and implemented. Useful information is extracted from the historical data to estimate the model forecast errors. Dominant
predictors and the predictors that exhibit evolving analogues are identified through cross validating the anomaly correlation
coefficients (ACC) among single predictors, meanwhile with reference of the results from the dynamic analogue bias correction
using four analogue samples. Next, an optimal configuration of multiple predictors is set up and compared with historical
optimal multi-predictor configurations and then dynamically adjusted. Finally, the model errors are evaluated and utilized
to correct the NCC operational seasonal prediction model results, and the forecast of monsoon precipitation is obtained at
last. The independent sample validation shows that this technique has effectively improved the monsoon precipitation prediction
skill during 2005–2009. This study demonstrates that the analogue-dynamical approach is feasible in operational prediction
of monsoon precipitation. 相似文献
109.
Jinfu Shu Xiaojia Chen I.-Ming Chou Wenge Yang Jingzhu Hu Russell J. Hemley Ho-kwang Mao 《地学前缘(英文版)》2011,2(1):93-100
The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure typesⅠ,Ⅱ,and H in diamond-anvil cells.The diffraction data for typesⅡ(sⅡ) and H(sH) were refined to the known structures with space groups Fd3m and P6_3/mmc,respectively.Upon compression,sⅠmethane hydrate transforms to the sⅡphase at 120 MPa,and then to the sH phase at 600 MPa.The sⅡmethane hydrate was found to coexist... 相似文献
110.
Sin Chan Chou Andr de Arruda Lyra Jorge Lus Gomes Daniel Andrs Rodriguez Minella Alves Martins Nicole Costa Resende Priscila da Silva Tavares Claudine Pereira Dereczynski Isabel Lopes Pilotto Alessandro Marques Martins Lus Felipe Alves de Carvalho Jos Luiz Lima Onofre Idalcio Major Manuel Penhor Adrito Santana 《Climate Dynamics》2020,54(9):4021-4042
Sao Tome and Principe is a small insular African country extremely vulnerable to rising sea levels and impacts such as inundation, shore line change, and salt water intrusion into underground aquifers. Projections of climate change have considered coarse model resolutions. The objective of this work is to dynamically downscale the global model projections to 4-km resolution and to assess the climate change in the Sao Tome and Principe islands. The global climate projections are provided by the Canadian Earth System Model under two Representative Concentration Pathways greenhouse gas scenarios, RCP4.5 and RCP8.5. The downscaling is produced by the Eta regional climate model. The baseline period is taken between 1971 and 2000, and the future climate period is taken between 2041 and 2070. The 2-m temperature simulations show good agreement with station data. The model simulates temperature more accurately than precipitation. The precipitation simulations systematically show underestimation and delay of the rainy and the dry seasons by about 1 month, a feature inherited from the global climate model. In the middle of the 21st century, projections show the strongest warming in the elevated parts of the Sao Tome Island, especially in February under RCP8.5. Warmer nights and warmer days become more frequent in the islands when compared with those in the present. While under RCP4.5, precipitation increases in the islands; under RCP8.5, it decreases everywhere in both islands. Heavy precipitation rates should increase, especially in the south-southwestern parts of the Sao Tome islands. Detailed spatial variability of the temperature and precipitation changes in the islands can only be revealed at very high spatial model resolution. Implications for the potential energy production from two major river basins are assessed in this work. 相似文献