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991.
东海陆架盆地位于欧亚板块的东南缘和西太平洋活动大陆边缘,本文选取了东海陆架盆地主要凹陷的17条地震剖面,采用平衡剖面技术,计算了主要凹陷新生代不同演化阶段的伸展率和压缩率。分析表明,东海陆架盆地构造演化总体由西向东跃迁。晚白垩世至晚古新世东海陆架盆地裂陷中心在西部坳陷带,始新世东迁至东部坳陷带,上新世东迁至东海陆架盆地东侧的冲绳海槽盆地。古新世中后期东海陆架盆地西部坳陷带北侧昆山凹陷反转;中新世东部坳陷带的西湖凹陷反转。东海陆架盆地西部坳陷带与东部坳陷带构造演化不同,证明了东海陆架盆地的东西分带。西部坳陷带北部的长江坳陷和南部的台北坳陷构造演化不同,东部坳陷带北部的西湖凹陷和南部的钓北凹陷构造演化不同,证明了东海陆架盆地的南北分块。 相似文献
992.
Atlanta’s urban heat island under extreme heat conditions and potential mitigation strategies 总被引:2,自引:0,他引:2
The urban heat island (UHI), together with summertime heat waves, foster’s biophysical hazards such as heat stress, air pollution,
and associated public health problems. Mitigation strategies such as increased vegetative cover and higher albedo surface
materials have been proposed. Atlanta, Georgia, is often affected by extreme heat, and has recently been investigated to better
understand its heat island and related weather modifications. The objectives of this research were to (1) characterize temporal
variations in the magnitude of UHI around Metro Atlanta area, (2) identify climatological attributes of the UHI under extremely
high temperature conditions during Atlanta’s summer (June, July, and August) period, and (3) conduct theoretical numerical
simulations to quantify the first-order effects of proposed mitigation strategies. Over the period 1984–2007, the climatological
mean UHI magnitude for Atlanta-Athens and Athens-Monticello was 1.31 and 1.71°C, respectively. There were statistically significant
minimum temperature trends of 0.70°C per decade at Athens and −1.79°C per decade at Monticello while Atlanta’s minimum temperature
remained unchanged. The largest (smallest) UHI magnitudes were in spring (summer) and may be coupled to cloud-radiative cycles.
Heat waves in Atlanta occurred during 50% of the years spanning 1984–2007 and were exclusively summertime phenomena. The mean
number of heat wave events in Atlanta during a given heat wave year was 1.83. On average, Atlanta heat waves lasted 14.18 days,
although there was quite a bit of variability (standard deviation of 9.89). The mean maximum temperature during Atlanta’s
heat waves was 35.85°C. The Atlanta-Athens UHI was not statistically larger during a heat wave although the Atlanta-Monticello
UHI was. Model simulations captured daytime and nocturnal UHIs under heat wave conditions. Sensitivity results suggested that
a 100% increase in Atlanta’s surface vegetation or a tripling of its albedo effectively reduced UHI surface temperature. However,
from a mitigation and technological standpoint, there is low feasibility of tripling albedo in the foreseeable future. Increased
vegetation seems to be a more likely choice for mitigating surface temperature. 相似文献
993.
准噶尔盆地西北缘克百地区二叠系沉积特征及沉积模式 总被引:1,自引:0,他引:1
准噶尔盆地西北缘二叠系是重要的产油层和储集层,通过岩心观察、薄片分析,结合测井和录井资料,对西北缘克百断裂下盘二叠系砂砾岩的沉积环境和沉积特征进行了深入研究。研究表明,该区砂砾岩既有水上冲积扇沉积环境沉积的,也有水下扇三角洲前缘沉积环境形成的。前者主要为棕褐色、泥质杂基含量高、分选和磨圆差,储层物性相对较差;后者经过了稳定水流的淘洗,杂基含量少,钙质或沸石类胶结发育,分选性和磨圆度也较高,其物性条件也明显较好。并据此建立了研究区冲积扇与扇三角洲有机结合的沉积模式,该模式突出了湖岸线的重要性,同时模糊冲积扇与扇三角洲之间的界限。并对冲积扇与扇三角洲各亚相的岩性特征、沉积结构和沉积序列进行了归纳和总结,为该区寻找二叠系优质储层提供借鉴和思路。 相似文献
994.
中国海相油气田勘探实例之十三 塔里木盆地东河塘海相砂岩油田勘探与发现 总被引:3,自引:1,他引:2
东河塘油田位于新疆库车县,构造上隶属于塔里木盆地塔北隆起轮台凸起东河塘断裂构造带,是我国发现的第一个高产高丰度海相砂岩油田,它的发现是中国海相砂岩油气勘探理论和实践的一次重大突破。油田发现于1990年7月,至1994年探明石油地质储量3323.13×104t,天然气地质储量15.5×108m3,至2009年底累计产原油825.75×104t。石炭系东河砂岩油藏是东河塘油田的主体,其储层东河砂岩段是一套滨岸相砂体,具有厚度巨大、埋深大、储集性能好的特点;其油藏类型为块状底水背斜油藏,产能高,储量丰度高。论述了东河塘油田勘探与发现的历程,剖析了取得勘探成功的实践认识与意义。 相似文献
995.
996.
A sea-survey was carried out along the Chinese coast from the Bohai Sea to South China Sea, and 15 surficial samples were
taken from major coastal estuaries, i.e., from north to south, the Yellow, abandoned Yellow, Yangtze, Qiantang, Ou, Min, Han,
and Pearl River estuaries. On the basis of clay mineral analysis and published data collection, this paper discusses the characteristics
of clay minerals of each coastal river and potentials of implications of sediment sources. The results show that the change
of diagnostic clay minerals from smectite to kaolinite from the Yellow to the Pearl River estuaries is southward, as clearly
shown by the ratios of smectite to chlorite (S/Ch) and kaolinite to illite (K/I). S/Ch decreases southward, while K/I moves
reversely, implying change in climate setting from cool/dry to humid/hot with intensified weathering processes. Besides, these
two indicators in the estuaries are also linked with the derivation of parent-rock of each river-basin and coastal hydrodynamics.
The disproportional higher ratio of K/I in the Yellow and abandoned Yellow River estuaries is ascribed to their sediment sources
with abundant loess component in the north-central China. The K/I decrease offshore from the Pearl River estuary is primarily
due to hydrodynamic sorting. Therefore, the S/Ch and K/I of the present study comprehensively reflect the controls of climate,
parent-rock, and sediment transport along the coast. 相似文献
997.
John Z. Shi Hong-Qiang Zhou Hua Liu Yong-Gang Zhang 《Environmental Earth Sciences》2010,61(8):1691-1702
Tidal flow and fine-sediment transport at the South Channel–North Passage of the partially-mixed Changjiang River estuary
were studied using a two-dimensional horizontal (2DH) numerical model. This 2DH model was achieved by depth-integrating the
momentum and convection–diffusion equations. The Alternating Direction Implicit scheme was used to solve the governing equations.
The iterative method was adopted for the calculation of convection and diffusion terms of momentum equation. Comparisons between
calculated and measured results (tidal elevations and depth-averaged velocities) have shown reasonable agreement. Horizontal
distributions of tidal current velocity and suspended sediment concentration were qualitatively consistent with observations.
Those modeled results were analyzed to elucidate the mechanisms for the formation of the turbidity maximum and intratidal
variations in fine-sediment transport processes. 相似文献
998.
In this paper, we propose a hybrid forecasting model to improve the forecasting accuracy for depth-averaged current velocities (DACVs) of underwater gliders. The hybrid model is based on a discrete wavelet transform (DWT), a deep belief network (DBN), and a least squares support vector machine (LSSVM). The original DACV series are first decomposed into several high- and one low-frequency subseries by DWT. Then, DBN is used for high-frequency component forecasting, and the LSSVM model is adopted for low-frequency subseries. The effectiveness of the proposed model is verified by two groups of DACV data from sea trials in the South China Sea. Based on four general error criteria, the forecast performance of the proposed model is demonstrated. The comparison models include some well-recognized single models and some related hybrid models. The performance of the proposed model outperformed those of the other methods indicated above. 相似文献
999.
Baohong Chen Kaiwen Zhou Kang Wang Jigang Wang Sumin Wang Xiuwu Sun Jinmin Chen Cai Lin Hui Lin 《海洋学报(英文版)》2022,41(1):1-2
This research investigated eight stations in Clarion-Clipperton Fracture Zone(CCFZ) in the eastern tropical Pacific in 2017 to study the spatial distribution characteristics of nutrients and chlorophyll a(Chl a) concentration,and compared nutrient concentrations and molar ratios with those of other investigations 20 years ago in the same area. The study found that dissolved inorganic nutrient(N, P and Si) concentrations were lowest in the upper layer, and increased from surface to some depths, t... 相似文献
1000.
Fangfang Kuang Jing Cha Junpeng Zhang Aijun Pan Hangyu Chen Xiwu Zhou Chunsheng Jing Xiaogang Guo 《海洋学报(英文版)》2022,41(11):1-11
In this paper, the intra-seasonal variability of the abyssal currents in the China Ocean Mineral Resources Association (COMRA) polymetallic nodule contact area, located in the western part of the Clarion and Clipperton Fraction Zone in the tropical East Pacific, is investigated using direct observations from subsurface mooring instruments as well as sea-surface height data and reanalysis products. Mooring observations were conducted from September 13, 2017 to August 15, 2018 in the COMRA contact area (10°N, 154°W). The results were as follows: (1) At depths below 200 m, the kinetic energy of intra-seasonal variability (20?100 d) accounts for more than 40% of the overall low-frequency variability, while the ratio reaches more than 50% below 2 000 m. (2) At depths below 200 m, currents show a synchronous oscillation with a characteristic time scale of 30 d, lasting from October to the following January; the energy of the 30-d oscillation increases with depth until the layer of approximately 4 616 m, and the maximum velocity is approximately 10 cm/s. (3) The 30-d oscillation of deep currents is correlated with the tropical instability waves in the upper ocean. 相似文献