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排序方式: 共有1117条查询结果,搜索用时 15 毫秒
1.
A new titanium (III) phosphite Ti2(HPO3)3, has been synthesized under hydrothermal conditions. The solid-state structure of this material was solved using single-crystal X-ray diffraction. The anionic inorganic skeleton has a three-dimensional structure, which is built up by TiO6 octahedral units linked together via bridging HPO3 pseudo pyramids, giving rise to tunnels along the three crystallographic axes. This new compound displays a high thermal stability limit of 625 °C. IR and Raman spectroscopies show the vibrational modes of the (HPO3)2−oxoanions. Electrochemical activity of this phase toward reversible insertion of Li ion was studied for the first time by galvanostatic charge-discharge measurements, an insertion host for reversible accommodation of Li+ was observed.  相似文献   
2.
Mobile devices with social media applications are the prevalent user equipment to generate and consume digital hate content. The objective of this paper is to propose a mobile edge computing architecture for regulating and reducing hate content at the user's level. In this regard, the profiling of hate content is obtained from the results of multiple studies by quantitative and qualitative analyses. Profiling resulted in different categories of hate content caused by gender, religion, race, and disability. Based on this information, an architectural framework is developed to regulate and reduce hate content at the user's level in the mobile computing environment. The proposed architecture will be a novel idea to reduce hate content generation and its impact.  相似文献   
3.
山东大学新校区环境设计   总被引:7,自引:0,他引:7  
张璐 《中国园林》2005,21(2):44-49
从空间分析的角度介绍山东大学新校区景观规划设计的构思,引申出对校园空间格局的探讨,为今后更好地从人文主义出发,创造宜人化的生活环境尺度提供借鉴.  相似文献   
4.
英国的城市规划体系在长期的发展完善过程中,逐步摸索建立了一套成熟的城市规划动态监测机制,其工作方法、技术路线、监督软件系统以及对于监管工作重点和难点的把握和处理经验,为我国建设城市规划动态监测机制系统提供了宝贵经验。本文对英国城市规划体系的新变化作了简要介绍,重点对地方发展框架的监测机制进行了分析研究,总结了英国的经验对我国正在建设的城市规划动态监测系统的借鉴意义。  相似文献   
5.
By managing a catchment effectively, the range and amount of contaminants entering waters used for public water supply can be reduced, with resultant benefits for both water companies and consumers. Consequently, catchment management is increasingly being recognised as being at the heart of the water environment. An overview of current and previous catchment management initiatives is given, along with the European Landscape Convention, which could be used as a vehicle for the implementation of a national catchment management strategy. The adoption of the drinking water safety plan approach is strongly advocated by the World Health Organisation, and effective catchment management underpins this approach. Effective management of our catchments will also make a significant contribution to meeting our obligations under the Water Framework Directive, by helping to address the serious issue of diffuse pollution from agriculture.  相似文献   
6.
This paper describes the development of a guidance tool for assessing the ability of a receiving watercourse to assimilate pollution from point discharges. The 'sustainable capacity tool'uses a framework that accounts for the 'no-deterioration'requirement of the Water Framework. Directive, in terms of the downgrading of a river-stretch classification and the requirement to return all rivers to 'good ecological status'. The second requirement results in a long-term set of river-quality targets or objectives, and it is generally assumed that 'good'refers to 'A2 quality in the Scottish Environmental Protection Agency classification system. The resulting sustainable capacity is defined as the risk-based amount of capacity that could be allocated without causing a failure of the target class and which could also result in a negative capacity if the river stretch is currently failing the target class. This is plotted as a GIS layer and is intended to form an overview of water quality to help inform stakeholders who are participating in a water-quality strategy for the next Scottish investment programme on Quality and Standards 3. The sustainable capacity tool could be used in conjunction with integrated catchment modelling for complete management of the Water Framework Directive river-basin districts.  相似文献   
7.
Acidification continues to be a major impact in freshwaters of northern Europe, and the biotic response to chemical recovery from acidification is often not a straightforward process. The focus on biological recovery is relevant within the context of the EU Water Framework Directive, where a biological monitoring system is needed that detects differences in fauna and flora compared to undisturbed reference conditions. In order to verify true reference sites for biological analyses, expected river pH is modeled based on Ca and TOC, and 94% of variability in pH at reference sites is explained by Ca alone, while 98% is explained by a combination of Ca and TOC. Based on 59 samples from 28 reference sites, compared to 547 samples from 285 non-reference sites, the impact of calcium and total organic carbon (TOC) on benthic algae species composition, expressed as acidification index periphyton (AIP), is analyzed. Rivers with a high Ca concentration have a naturally higher AIP, and TOC affects reference AIP only at low Ca concentrations. Four biological river types are needed for assessment of river acidification in Norway based on benthic algae: very calcium-poor, humic rivers (Ca < 1 mg/l and TOC > 2 mg/l); very calcium-poor, clear rivers (Ca < 1 mg/l and TOC < 2 mg/l); calcium-poor rivers (Ca between 1 and 4 mg/l); moderately calcium rich rivers (Ca > 4 mg/l). A biological assessment system for river acidification in Norway based on benthic algae is presented, following the demands of the Water Framework Directive.  相似文献   
8.
Priority pollutants in wastewater and combined sewer overflow   总被引:3,自引:1,他引:3  
Implementation of the European Water Framework Directive and its affiliated directives requires Member States to improve their understanding of priority pollutants (PPs) in urban areas and obviously within wastewater systems. As a direct consequence, this study is intended to furnish data on both PP occurrence and the significance of concentrations in wastewater during dry and wet periods within combined sewers. Various sampling sites within the Paris combined sewer network were selected; for each sample, a total of 66 determinants, including metals, polycyclic aromatic hydrocarbons (PAHs), pesticides, organotins, volatile organic compounds, chlorobenzenes, phthalates and alkylphenols, were analysed. A broad range of PPs was observed in wastewater during dry as well as wet weather periods. Of the 66 elements investigated, 33 and 40 priority substances could be observed in raw sewage and wet weather effluent, respectively. As expected, a majority of metals were present in all samples, reflecting their ubiquitous nature. For both periods, chlorobenzenes and most of the pesticides always remained below the limit of quantification, while the majority of other organic pollutants assessed were identified within the microg l(-1) range. As highlighted by the larger number of substances detected in wet weather samples and the significance of their concentrations, runoff via atmospheric inputs and/or surface leaching was found to induce a wider range of PPs (n=40) and lead to higher concentrations of certain metals, PAHs, pesticides and other individual compounds. The data generated during this survey, which constitutes one of the first studies conducted in Europe to report concentrations for a variety of priority substances in wastewater within combined sewers, may be used in the future to identify PPs of potential significance for dry and wet weather periods and targeted for further investigation.  相似文献   
9.
Characterisation of faecal indicator organism (FIO) concentrations and export coefficients for catchments with particular combinations of land use and under specific climatic regimes is critical in developing models to predict daily loads and apportion sources of the microbial parameters used to regulate water quality. Accordingly, this paper presents a synthesis of FIO concentration and export coefficient data for the summer bathing season, with some comparative winter data, for 205 river/stream sampling points widely distributed across mainland UK. In terms of both geometric mean (GM) FIO concentrations and export coefficients (expressed as cfu km(-2) h(-1)), the results reveal (1) statistically significant elevations at high flow compared with base flow, with concentrations typically increasing by more than an order of magnitude and export coefficients by about two orders; (2) significantly higher values in summer than in winter under high-flow conditions; and (3) extremely wide variability between the catchments (e.g. four orders of magnitude range for GM faecal coliform concentrations), which closely reflects land use-with urban areas and improved pastures identified as key FIO sources. Generally, these two most polluting land uses are concentrated in lowland areas where runoff (m3 km(-2) h(-1)) is low compared with upland areas, which in the UK are dominated by rough grazing and forestry. Consequently, contrasts in export coefficients between land use types are less than for FIO concentrations. The GMs reported for most land use categories are based on 13 sites and exhibit quite narrow confidence intervals. They may therefore be applied with some confidence to other catchments in the UK and similar geographical regions elsewhere. Examples are presented to illustrate how the results can be used to estimate daily summer base- and high-flow FIO loads for catchments with different land use types, and to assess the likely effectiveness of certain strategies for reducing FIO pollutant loadings in areas with extensive areas of lowland improved pasture.  相似文献   
10.
由二氧化碳等温室气体排放引起的 全球气候变化已经成为本世纪人类面临的 最大挑战之一。习近平总书记在第75届联合 国大会一般性辩论上宣布了中国实现碳达 峰、碳中和的“30·60”目标,而探寻具有预 防性、低成本、长期效益的碳减排途径是兑 现我国气候承诺的前提与保证。首先分析了 中国当前以技术进步为核心的碳减排途径的 不完备性,提出结构调整式减排概念,并论 证了空间规划作为具有引领性的结构调整式 减排手段具有不可替代的碳约束作用,是达 成区域长远碳约束目标的系统性、根本性途 径。进而以“空间规划—城乡用地—碳排放 效应”为核心视角,对空间规划应具有的碳 减排的内在机制进行了分析,明确了空间规划 通过“边界管控”“用途管控”“位置管控”和 “指标管控”四种基本的调控手段作用于城 乡用地的规模、结构、布局和强度四个维度的 变化,形成对区域系统碳排放效应的控制。 最后从“确立碳管控主体”“核算碳排放效 应”及“制定碳约束方案”三方面构建起空间规划的碳排放约束框架,为空间规划履行碳约束职能、促进气候共同利益提出具体路径指导。  相似文献   
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