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531.
Paulina Montero Giovanni Daneri L. Antonio Cuevas Humberto E. González Bárbara Jacob Lorena Lizárraga Eduardo Menschel 《Progress in Oceanography》2007,75(3):518-530
Recurrent coastal upwelling is recognized as one of the main factors promoting the exceptionally high productivity of the Humboldt Current System. Herein, we study time series data of gross primary production (2003-2006) and its fluctuation in relation to seasonal changes in the light and nutrient field of the Concepción upwelling ecosystem. Concurrent measurements of gross primary production, community respiration, bacterial secondary production, and sedimentation rates allowed a characterization of the main carbon fluxes and pathways in the study area. The integrated values of gross primary production were higher during the upwelling period (>1 g C m−2 d−1; October-April; that is, early spring to early austral fall). Seasonal changes in the system were also reflected in community respiration, organic matter sedimentation, and bacterial production rates, which varied along with the gross primary production. The significant correlation between gross primary production and community respiration (Spearman, r = 0.7; p < 0.05; n = 18) reflected an important degree of coupling between organic matter formation and its usage by the microplanktonic community during periods when gross primary production/community respiration were highly similar. Higher gross primary production values (>6 g C m−2 d−1) were consistently associated with maximum biomass levels of Skeletonema costatum and Thalassiosira subtilis. We observed a positive correlation between gross primary production and the sedimentation of intact diatom cells (Spearman, r = 0.5, p < 0.05, n = 17). Our data suggest that, in the Concepción upwelling ecosystem, bacteria utilize an important fraction of the gross primary production. If our interpretations are correct, they leave unanswered the question of how the system supports the extremely high fish biomass levels, therein pointing out the system’s limited capacity to buffer the evasion of CO2 following upwelling. 相似文献
532.
Three completing methods were introduced in this paper. The data were completed from 1983 to 1988 at the KL and PTC stations. The completed data were called original data. The completing methods were the transfer function with fixed-parameters then built the Transfer Function (TF) model between the two stations. The TF model was used to estimate the wave data of the future. The difference of the estimated data and the original data were conferred in this paper. Two types of forecasting differences were discussed here: (1) the input data year increases from 1 to 6 years, and the difference of the estimated data and the original data were then compared. (2) Use one-year data as the input series to forecast the data of the next five years, and then compare the differences of the estimated data and the original data. After comparing the differences we can know the results. The mean value and the standard deviation of the differences decrease and go more stable as the quantity of the input data year increases. The mean value and the standard deviation of the differences increase and go more unstable as the quantity of the forecasted data year increases. This model can be used to forecast the wave data. 相似文献
533.
The appropriate delivery of primary care services, an important policy imperative in many developed nations, is contingent on defining appropriate geographies to which these services are delivered. Primary Care Service Area (PCSA) geographies have been created in some countries to facilitate primary care policy making and have been utilized in a large body of research. In spite of their extensive use across rural and urban settings, the usefulness of PCSAs has not been evaluated. In this study, for the first time we put PCSAs to the test by comparing them to another small area geography - Postal Areas, and by exploring their usefulness in measuring relationships between Primary Care Practitioner supply and use. We find while PCSAs are better than Postal Areas in measuring relationships between General Practitioner supply and visits by patients, this relationship shows some heterogeneity across areas. 相似文献
534.
Siobhán Rachel McPhee 《Urban geography》2016,37(3):396-415
The city has become the context for a dialectical relationship not only between the global and the local but also between migrants and the host society. Whilst there is considerable work on migrant integration, integration is rarely examined from the perspective of the workplace, or from a geographic perspective, which problematizes the spatiality of migrant workers’ experiences. This article studies migrant workers in low-skilled jobs, with a focus on Temporary Service Sector Providers in catering, cleaning, and security, in order to understand how they negotiate their position in the city and are active agents of this negotiation. The study, based upon a survey of 60 migrants complemented by 20 in-depth interviews, questions how integration should be understood: in particular it suggests that—in some respects—integration may be difficult for all low-wage precarious workers, whether migrants or not. The study also highlights how migrant workers retain agency—the capacity to act, to make decisions, and appropriate certain places—even in challenging circumstances. 相似文献
535.
交通拥堵对急救医疗服务时空可达性的影响——以广州市为例 总被引:2,自引:2,他引:0
时间是急救服务的敏感因素,急救服务设施可达性的时空差异对于评估急救设施的选址及急救服务调度的效率,解决公众急救医疗需求与供给之间的矛盾,辅助政府部门的决策都至关重要。交通拥堵是常见的城市问题,尤其是在城市中心区域更为明显,由于交通拥堵带来的时间滞后对急救服务产生的影响不容忽视。本文通过浮动车GPS大数据,分析交通拥堵对广州市中心城区急救医疗设施时空可达性的影响。结果表明:①在考虑道路实际通行状况的情况下,在交通高峰期,社区的急救医疗服务平均可达时间和最长可达时间分别比采用设计时速计算增加20%和25%。②可达性存在明显的时空差异。急救医疗服务可达性以急救医院为中心,沿着路网向四周呈现衰减趋势。急救医院布局较多、路网密集区域的可达性高,反之则低。交通拥堵对路网密集、行车规则设计复杂以及存在通过性交通流的地区影响显著。③对不同阻抗系数下可达性变化的敏感性分析,发现随着阻抗系数的增大,可达性变化的趋势有所放缓,紧急医疗服务可达性的分异变小;这一变化趋势在交通平峰期表现更为明显。因此,在研究城市中心区域急救医疗服务时,考虑交通拥堵对可达性的影响,需要构建基于实时交通状况的可达性评估模型,合理选择模型参数,优化实时急救医疗服务调度,提升急救服务的效率和质量。 相似文献
536.
The provision of care is an increasingly pressing issue in the Global North. With an ageing population and policies encouraging women into the labour market, there is a growing need for workers to undertake paid caring. This poses important and urgent questions about the social organisation of labour markets. Care work typically is low paid and undertaken in precarious, informal, or temporary situations. Many posts are filled by economic migrants, raising concerns about a care deficit in sending countries. In this paper we examine the ‘caring work’ undertaken by migrant workers in a West London Hospital. We employ a twofold characterisation of caring work. Like other bottom-end service sector work, this work is characterised by the face-to-face ‘emotional labour’. However, it also requires ‘body work’: close and often intimate physical contact between carers and those they care for. We argue that both of these aspects are important in understanding how caring work is constructed as poorly regarded and low paid. We show how these features play out in particular ways for migrant workers employed in such caring work. 相似文献
537.
538.
淄博市国土资源局淄川分局自2003年设立办文服务窗口7年来,从制度建设、人员管理、服务方式、廉政和作风效能建设等方面努力推进窗口工作,进一步提高政务公开和依法行政水平,在推进窗口办文制度方面起到了积极作用。 相似文献
539.
当前的LBS应用系统多采用独立构建方式,将LBS通用服务功能与应用系统相关功能集成,使系统内部耦合程度较高,虽然能够保证应用系统的完整性,但导致LBS通用服务功能难以共享,造成系统的扩展性差以及数据、计算资源的浪费。该文探索了面向多应用系统的位置公共服务(LBCS)的服务模式与系统体系结构。基于这种服务模式,位置服务系统将由两大部件构成:LBS公共服务平台和专业应用系统,且LBS公共服务平台能被多个应用系统使用。 相似文献
540.
Until recently, the Global Positioning System (GPS) was the only operational means of distributing time to an arbitrary number
of users and of synchronizing clocks over large distances with a high degree of precision and accuracy. Over the last few
years it has been shown that similar performance can be achieved using the Russian Global Navigation Satellite System (GLONASS).
GLONASS time transfer between continents was initially hampered by the lack of post-processed precise ephemerides. Results
from the International GLONASS Experiment (IGEX) campaign are now available, however, and this paper reports on the first
use of IGEX precise ephemerides for GLONASS P-code intercontinental time links. The results of GLONASS P-code and GPS C/A-code
time transfer are compared under similar conditions.
Received: 31 January 2000 / Accepted: 10 July 2000 相似文献