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41.
Two-phase partitioning bioreactors offer many advantages for the removal of toxic pollutants. In particular, such systems can be loaded with very large quantities of pollutants without risks of microbial inhibition, they are self-regulated and they prevent the risks of hazardous pollutant volatilisation during aerobic treatment. However, their potential has never been tested at low temperatures. Phenol biodegradation by a cold adapted Pseudomonas strain was therefore tested at 14 or 4 degrees C using 2-undecanone, diethyl sebacate or 2-decanone as organic phases in a two-phase partitioning bioreactor. The three solvents were biocompatible at 14 degrees C but evidence was found that diethyl sebacate was biodegraded by the bacteria and this solvent was not tested further. Although only 2-decanone was suitable at 4 degrees C, phenol biodegradation was more efficient in 2-undecanone at 14 degrees C, reaching a maximum volumetric rate (based on the volume of aqueous phase) of approximately 1.94 g/L.day after 47 h of cultivation. In 2-decanone at 14 degrees C, evidence was found that phenol degradation was limited by the release of biosurfactants, which increased the solubility and toxicity of the solvent in the aqueous phase inhibiting microbial activity. This study therefore shows that pollutant removal at low temperature is feasible but that the production of biosurfactants can have a negative impact on the process and must be taken into consideration when selecting the organic solvent. Future work should therefore focus on the selection of solvents suitable for use at temperatures below 14 degrees C. 相似文献
42.
We analyze a sample of 72 IPO firms that went public between 1992 and 1996 for which we have detailed proprietary information about the amount and cost of D&O liability insurance. If managers of IPO firms are exploiting superior inside information, we hypothesize that the amount of insurance coverage chosen will be related to the post-offering performance of the issuing firm's shares. Consistent with the hypothesis, we find a significant negative relation between the three-year post-IPO stock price performance and the insurance coverage purchased in conjunction with the IPO. One plausible interpretation is that, like insider securities transactions, D&O insurance decisions reveal opportunistic behavior by managers. This provides some motivation to argue that disclosure of the details of D&O insurance decisions, as is required in some other countries, is valuable. 相似文献
43.
The objective of this paper is to analyse how much the traditions of history research (HR) and futures research (FR) have in common and how they could assist each other. First, the role of time is analysed. Second, the path dependence theory, strategic decision-making, knowledge management and visionary management are discussed. Examples of the application of the latter in water and sanitation services and their long-term development are shown. Finally, some argumented views are presented on how the convergence between FR and HR could be improved.The key point of this research is the seeming discontinuity between presents, recent pasts and near futures. The traditions of HR probably make it more difficult to assess the effects of strategic decisions on the recent. If more convergence is wanted, the gap should be filled somehow. On the other hand, the core of FR research seems to concentrate more on strategic and visionary horizons while perhaps neglecting the operational horizon of the near future. 相似文献
44.
Alice Y. L. Lui 《Thunderbird国际商业评论》1996,38(3):389-401
This article aims to bridge the gap between an oriental culture and a western approach to management concepts and practice with a view to exploring a culturally fit style of management for China. Comparisons are drawn between the teachings of early Chinese philosophers and scholars with those of their western counterparts. It is envisaged that hidden links may be eventually found so that management as a universal concept with cultural variations may be the trend in the nineties and beyond. 相似文献
45.
The transformation of aluminium species in the processes of coagulation, sedimentation and filtration. 总被引:1,自引:0,他引:1
The aluminium toxicity is closely related to aluminium species. In this work aluminium was fractionated into seven forms: Al(T), Al(Sus), Al(C + S), Al(S), Al(C), Al(O) and Al(I). Four Al-based coagulants and simulated raw water were used in the laboratory to investigate the aluminium transformation in coagulation, sedimentation and filtration processes. It is the use of Al-based coagulants that contributes more to the increase of the residual aluminium for the low-turbidity raw water, while the Al-based coagulants, especially the polymeric aluminium coagulants, work to remove the aluminium from the high-turbidity raw water. In the case of traditional coagulants, the increase of the turbidity or the dissolved organic carbon (DOC) concentration in the raw water results in a high concentration of Al(C + S). The removal rate of aluminium species in the filtration process is not only related to its size: RAl(Sus) > RAl(C+S), RAl(C) > RAl(S), but also to the physicochemical properties of aluminium species and filter. For the kaolin-polyaluminium chloride system, a lower removal rate of aluminium species results is due to the complexation of humic acid and aluminium species. 相似文献
46.
A pilot-scale fluidised pellet bed (FPB) bioreactor, which combines chemical coagulation, biological degradation, particle pelletisation and separation in one unit, was applied for onsite wastewater treatment and reuse. As a result of rational use of inorganic coagulant and organic polymer and moderate mechanical agitation, spherical particles were generated in the upflow column and a well-fluidised bed was formed. With a continuous supply of dissolved oxygen through a recycling loop, an aerobic condition was kept in the bottom section of the FPB column. Under such conditions the pellets in the FPB column showed the following characteristics: (1) compact structure and high density; (2) rich in microorganisms; and (3) high MLSS and MLVSS concentrations. Therefore, the FPB bioreactor achieved more than 90% removal of SS, COD, BOD and TP from raw domestic wastewater within a total hydraulic retention time (HRT) of only about 30 minutes. It also showed nitrification and denitrification ability and the TN removal could be about 50% as the recycling ratio was increased to 1:1. The treated water quality is generally competitive with the secondary effluent from a conventional activated sludge process. With these advantages the FPB bioreactor is recommendable as a compact system for onsite wastewater treatment and reuse. 相似文献
47.
Peter Lok Richard Y. Hung Paul Walsh Paul Wang John Crawford 《Journal of Management Studies》2005,42(7):1357-1381
abstract Studies on the three types of process improvement programmes (Continuous Improvement, Reengineering and Benchmarking) have appeared many times in the literature. These studies suggest that certain organizational variables act as enablers and their presence or absence can significantly influence success rates. Such studies have tended to examine companies where a single programme has been implemented. In contrast, this paper examines a sample of companies who have experienced all three programmes. Our aim is to compare and contrast each programme's impact on firm performance and identify which organizational variables are common and which are programme-specific enablers of success. We build and test an integrative framework to support our analysis. Our study found that: (1) Reengineering delivered the greatest impact on performance; (2) executive commitment was needed to make this happen; (3) strategic alignment was the major influence on the success rate of Reengineering and Continuous Improvement programmes; and (4) employee empowerment was necessary for each programme to work effectively. 相似文献
48.
In this paper, we propose an estimator for the population mean when some observations on the study and auxiliary variables
are missing from the sample. The proposed estimator is valid for any unequal probability sampling design, and is based upon
the pseudo empirical likelihood method. The proposed estimator is compared with other estimators in a simulation study. 相似文献
49.
In this study, a scenario-based interval-stochastic fraticle optimization with Laplace criterion (SISFL) method is developed for sustainable water resources allocation and water quality management (WAQM) under multiple uncertainties. SISFL can tackle uncertainties presented as interval parameters and probability distributions; meanwhile, it can also quantify artificial fuzziness such as risk-averse attitude in a decision-making issue. Besides, it can reflect random scenario occurrence under the supposition of no data available. The developed method is applied to a real case of water resources allocation and water quality management in the Kaidu-kongque River Basin, where encounter serve water deficit and water quality degradation simultaneously in Northwest China. Results of water allocation pattern, pollution mitigation scheme, and system benefit under various scenarios are analyzed. The tradeoff between economic activity and water-environment protection with interval necessity levels and Laplace criterions can support policymakers generating an effective and robust manner associated with risk control for WAQM under multiple uncertainties. These discoveries avail local policymakers gain insight into the capacity planning of water-environment to satisfy the basin’s integrity of socio-economic development and eco-environmental sustainability. 相似文献
50.