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121.
Fine sediment represents an important diffuse source pollutant in surface waters, due to its role in governing the transfer and fate of many substances, including nutrients, heavy metals, pesticides and other organic contaminants, and its influence on aquatic ecology. Therefore, catchment management strategies frequently need to include provision for the control of sediment mobilization and delivery. The sediment tracing concept provides a valuable framework for assisting the management and control of diffuse source sediment pollution by identifying the key sources and demonstrating the importance of intermediate storages and the likely impact of upstream mitigation strategies on downstream sediment and sediment associated contaminant fluxes. In this research, fine sediment sources were identified using tracing method. By field works, sediments were sampled from dam reservoir, different sources were also sampled. Fifteen tracers were first selected for tracing which are: The amounts of N, P, C, Cr, Co, Mg, K, Na, smectite, chlorite, illite, kaolinite, and two magnetic properties consisting of LOW Frequency Magnetic Susceptibility (X(LF)) and Frequency Dependent Magnetic Susceptibility (X(FD)). The samples were analyzed in the laboratory for these parameters and different statistical methods were applied to the data including Non-parametric Kruskal-Wallis Test and Stepwise Discriminant function analysis. The results provide important information on the relative importance of fine sediment sources to the reservoir sediments, which can be used to support model validation and the targeting of management and control strategies. 相似文献
122.
Fletcher TD Walsh CJ Bos D Nemes V RossRakesh S Prosser T Hatt B Birch R 《Water science and technology》2011,64(2):494-502
Urbanisation results in changes to runoff behaviour which, if not addressed, inevitably degrade receiving waters. To date, most stormwater management has focussed on the streetscape and public open space. Given that much of the catchment imperviousness is located on private land, we developed and tested a novel economic instrument (a uniform price auction) for encouraging allotment-scale stormwater retention. We evaluated bids using an integrated environmental benefit index (EBI), based on the ability of the proposed works to reduce runoff frequency, pollutant loads and to reduce potable water demand. The uniform price auction resulted in 1.4 ha of impervious areas being effectively 'disconnected' from the stormwater system. The EBI provided an objective and transparent method of comparing bids, which varied in the type of works proposed (e.g. rainwater tank, rain-garden), the cost and the resulting environmental benefit. Whilst the pilot auction was a success, the public subsidy of works undertaken was around 85%, meaning that property owners a relatively small private benefit in the works. Future auction rounds will be revised to (i) test an EBI which is more focussed on the protection of streams (assessing changes to runoff frequency, baseflow volumes and water quality) and (ii) provide an auction process which is simpler to understand, and provides greater practical support for landholders who wish to undertake works. 相似文献
123.
Degradation of the lower chlorinated ethenes is crucial to the application of natural attenuation or in situ bioremediation on chlorinated ethene contaminated sites. Recently, within mixtures of several chloroethenes as they can occur in contaminated groundwater inhibiting effects on aerobic chloroethene degradation have been shown. The current study demonstrated that metabolic vinyl chloride (VC) degradation by an enrichment culture originating from groundwater was not affected by an equimolar concentration (50 μM) of cis-1,2-dichloroethene (cDCE). Only cDCE concentrations at a ratio of 2.4:1 (initial cDCE to VC concentration) caused minor inhibition of VC degradation. Furthermore, the degradation of VC was not affected by the presence of trans-1,2-dichloroethene (tDCE), 1,1-dichloroethene (1,1-DCE), trichloroethene (TCE), and tetrachloroethene (PCE) in equimolar concentrations (50 μM). Only cDCE and tDCE were cometabolically degraded in small amounts. The VC-degrading culture demonstrated a broad pH tolerance from 5 to 9 with an optimum between 6 and 7. Results also showed that the culture could degrade VC concentrations up to 1,800 μM (110 mg/L). 相似文献
124.
Understanding urban residential end uses of water 总被引:1,自引:0,他引:1
The 'end use' of water is a breakdown of the total household water usage such as water used for toilets, showers, washing machines, taps, lawn watering, etc. Understanding end uses of water will enable water planners, water authorities and household owners determine where water is used/wasted, how much and how often. This paper describes the end uses of water from a number of single-family homes in Greater Melbourne, Australia. The study involves the analysis of water consumption data recorded at 5-s intervals from logged households collected by Yarra Valley Water in Melbourne in 2004. The study determines how much water is used for outdoor and indoor purposes in a single-family home in Melbourne and compares the water usage during winter and summer. Hourly patterns of major end uses of water are also developed. The aim of this study is to improve the understanding of the end uses of water and to assist where to focus water conservation efforts that would be most effective financially and environmentally, and be acceptable to everyone. 相似文献
125.
While the use of environmental factors in the analysis and prediction of failures of buried reticulation pipes in cold environments has been the focus of extensive work, the same cannot be said for failures occurring on pipes in other (non-freezing) environments. A novel analysis of pipe failures in such an environment is the subject of this paper. An exploratory statistical analysis was undertaken, identifying a peak in failure rates during mid to late summer. This peak was found to correspond to a peak in the rate of circumferential failures, whilst the rate of longitudinal failures remained constant. Investigation into the effect of climate on failure rates revealed that the peak in failure rates occurs due to differential soil movement as the result of shrinkage in expansive soils. 相似文献
126.
Vankerckhoven E Verbessem B Crauwels S Declerck P Muylaert K Willems KA Rediers H 《Water science and technology》2011,64(6):1247-1253
The main objective of this study is to explore possible synergistic or additive effects of combinations of chemical disinfectants (sodium hypochlorite, peracetic acid, hydrogen peroxide, chlorine dioxide) and UV in their efficacy in inactivating free-living bacteria and removing biofilms. In contrast to most studies, this study examines disinfection of municipal water in a pilot-scale system using a mixed bacterial suspension, which enables a better simulation of the conditions encountered in actual industrial environments. It was shown that the combination of either hypochlorite, hydrogen peroxide, peracetic acid, or chlorine dioxide with UV yielded additive effects on the inactivation of free-living bacteria. Actual synergy was observed for the combination of UV and 5 ppm hydrogen peroxide. Regarding biofilm treatment, additive effects were observed using the combination of hydrogen peroxide and UV. The promising results obtained in this study indicate that the combination of UV and chemical disinfectants can considerably reduce the amount of chemicals required for the effective disinfection and treatment of biofilms. 相似文献
127.
Shortcut nitrification has been successfully applied in a laboratory scale nitrification-denitrification process consisting of an up-flow anaerobic sludge blanket (UASB) and an aerobic membrane bioreactor (MBR) in treating synthetic and municipal wastewater to simultaneously remove organic carbon and nitrogen. For the treatment of synthetic wastewater, the combined system exhibited a high TOC removal of 98% with a steady ammonia removal efficiency of about 98% in the MBR and a total nitrogen (TN) removal efficiency of 90%. In treating municipal wastewater, due to its low COD concentration, removal efficiencies of TOC, ammonia and TN were 70%, 98% and 60%, respectively. The biogas production was around 76.4 L/m3 wastewater when treating synthetic wastewater. However, little biogas was produced when treating municipal wastewater which was the result of low organic carbon loading to the UASB. Energy analysis has demonstrated that this novel shortcut nitrification process could consume less energy than a conventional process and have the potential of bio-energy generation via biogas production thus helping to achieve a more favorable energy balance. 相似文献
128.
Pons MN Potier O Pontvianne S Laurent N France X Battaglia P 《Water science and technology》2011,64(3):602-609
In order to characterize the pollution discharged into the Moselle River and some of its tributaries, spectroscopic techniques, namely UV-vis spectroscopy and synchronous fluorescence spectroscopy, have been combined. UV-visible spectra were analysed using the maximum of the second derivative at 225 nm (related to nitrates), the SUVA254 and E2/E3 indices (related to the nature of organic matter). Synchronous fluorescence spectra (delta lambda = 50 nm) presented different shapes depending upon the type of pollution. The pollution results from anthropogenic activities: untreated domestic sewage due to misconnections in a periurban river, effluent from urban WWTPS, agricultural runoff (nitrates) in several streams, discharge from a paper mill (humic-like substances due to wood processing) and from steel mills (PAHs). 相似文献
129.
130.