首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6004篇
  免费   933篇
  国内免费   168篇
电工技术   196篇
技术理论   2篇
综合类   418篇
化学工业   2295篇
金属工艺   158篇
机械仪表   165篇
建筑科学   286篇
矿业工程   119篇
能源动力   164篇
轻工业   210篇
水利工程   47篇
石油天然气   52篇
武器工业   9篇
无线电   668篇
一般工业技术   698篇
冶金工业   229篇
原子能技术   32篇
自动化技术   1357篇
  2024年   18篇
  2023年   142篇
  2022年   114篇
  2021年   416篇
  2020年   315篇
  2019年   219篇
  2018年   314篇
  2017年   273篇
  2016年   297篇
  2015年   309篇
  2014年   517篇
  2013年   410篇
  2012年   293篇
  2011年   420篇
  2010年   304篇
  2009年   322篇
  2008年   277篇
  2007年   310篇
  2006年   286篇
  2005年   205篇
  2004年   178篇
  2003年   179篇
  2002年   153篇
  2001年   114篇
  2000年   110篇
  1999年   82篇
  1998年   77篇
  1997年   72篇
  1996年   43篇
  1995年   25篇
  1994年   52篇
  1993年   35篇
  1992年   34篇
  1991年   22篇
  1990年   15篇
  1989年   16篇
  1988年   18篇
  1987年   8篇
  1986年   8篇
  1985年   12篇
  1984年   25篇
  1983年   13篇
  1982年   9篇
  1981年   8篇
  1980年   6篇
  1979年   9篇
  1978年   5篇
  1977年   7篇
  1976年   2篇
  1957年   1篇
排序方式: 共有7105条查询结果,搜索用时 15 毫秒
991.
Many tasks in geometry processing are modelled as variational problems solved numerically using the finite element method. For solid shapes, this requires a volumetric discretization, such as a boundary conforming tetrahedral mesh. Unfortunately, tetrahedral meshing remains an open challenge and existing methods either struggle to conform to complex boundary surfaces or require manual intervention to prevent failure. Rather than create a single volumetric mesh for the entire shape, we advocate for solid geometry processing on deconstructed domains, where a large and complex shape is composed of overlapping solid subdomains. As each smaller and simpler part is now easier to tetrahedralize, the question becomes how to account for overlaps during problem modelling and how to couple solutions on each subdomain together algebraically. We explore how and why previous coupling methods fail, and propose a method that couples solid domains only along their boundary surfaces. We demonstrate the superiority of this method through empirical convergence tests and qualitative applications to solid geometry processing on a variety of popular second‐order and fourth‐order partial differential equations.  相似文献   
992.
The rise of mobile apps is compelling ambitious companies to rush to market their own branded apps in hopes of building customers’ brand loyalty. By applying service-dominant logic, the lens of affordance, and two brand perceptions (brand competence and brand warmth), this study explores critical determinants of app continuance intention and brand loyalty among app users. Five affordances of branded apps are linked to value-in-use, which contributes both directly and indirectly to the two loyalty-related outcomes, through either brand competence or brand warmth. Data collected from 634 app users support all proposed hypotheses. Theoretical and practical implications are discussed.  相似文献   
993.
Black phosphorus (BP) has increasingly attracted scientific attention since its first applications in biomedicine due to its unique properties and excellent biocompatibility. In particular, its layer‐dependent bandgap, moderate carrier mobility, large surface‐area‐to‐volume ratio, biodegradability, intrinsic photoacoustic properties, and biocompatibility make it an ideal candidate for use in photothermal therapy, photodynamic therapy, drug delivery, 3D printing, bioimaging, biosensing, and theranostics, which are reviewed here. In addition, the article discusses strategies to overcome challenges related to surface instability due to chemical degradation, a major obstacle for its application. This review not only provides a comprehensive summary on BP preparation and biomedical applications but also summarizes recent research and future possibilities.  相似文献   
994.
Guaranteeing a certain delay threshold for delay‐sensitive applications in long term evolution (LTE) cellular communication system is a very challenging mission. By implementing an optimal scheduling strategy, this mission will be achieved. In this article, a novel scheduler is introduced in order to meet a predefined level of service quality by guaranteeing a specific delay threshold for delay‐sensitive applications in LTE cellular systems. The proposed scheduler assigns the available resource blocks (RBs) to active user equipments (UEs) tacking into consideration several attributes. The expiration date of each packet, the channel quality, the average data rate previously achieved by each UE, and the number of dropped packets for each UE compared with the average number of packets totally dropped are all considered in the proposed scheduler working mechanism. Consequently, the proposed scheduling strategy reduces the number of packets dropped for multimedia applications, and at the same time maximizes the overall throughput of the network. Simulation results are provided to study and evaluate the performance of the proposed scheduling strategy. A comparative study is presented between the proposed strategy and the most recent scheduling techniques. The obtained results prove that the proposed scheduling strategy has considerably acceptable and appreciated results compared with the results of the state‐of‐the‐art scheduling techniques.  相似文献   
995.
Surface modification of nanomaterials is essential for their biomedical applications owing to their passive immune clearance and damage to reticuloendothelial systems. Recently, a cell membrane‐coating technology has been proposed as an ideal approach to modify nanomaterials owing to its facile functionalized process and good biocompatibility for improving performances of synthetic nanomaterials. Here, recent advances of cell membrane‐coated nanomaterials are reviewed based on the main biological functions of the cell membrane in living cells. An overview of the cell membrane is introduced to understand its functions and potential applications. Then, the applications of cell membrane‐coated nanomaterials based on the functions of the cell membrane are summarized, including physical barrier with selective permeability and cellular communication via information transmission and reception processes. Finally, perspectives of biomedical applications and challenges about cell membrane‐coated nanomaterials are discussed.  相似文献   
996.
997.
为解决基于Docker容器的应用跨异构容器云迁移的问题,针对主流的异构容器编排引擎的编排原理进行了研究,同时也研究了主流容器服务提供商之间的异构性,在此基础上提出了基于Docker容器的应用跨异构容器云迁移的三层模型。为提高基于Docker容器的应用跨异构容器云迁移的效率,提出基于镜像预同步的应用迁移技术。实验结果表明,利用三层模型能成功实现应用跨异构容器云的迁移,并且在引入镜像预同步技术前后,同构云异构容器编排引擎之间的应用迁移时间平均减少了60.33%,异构云Kubernetes集群间的应用迁移时间平均减少了43.67%。  相似文献   
998.
3D point cloud data obtained from laser scans, images, and videos are able to provide accurate and fast records of the 3D geometries of construction-related objects. Thus, the construction industry has been using point cloud data for a variety of purposes including 3D model reconstruction, geometry quality inspection, construction progress tracking, etc. Although a number of studies have been reported on applying point cloud data for the construction industry in the recent decades, there has not been any systematic review that summaries these applications and points out the research gaps and future research directions. This paper, therefore, aims to provide a thorough review on the applications of 3D point cloud data in the construction industry and to provide recommendations on future research directions in this area. A total of 197 research papers were collected in this study through a two-fold literature search, which were published within a fifteen-year period from 2004 to 2018. Based on the collected papers, applications of 3D point cloud data in the construction industry are reviewed according to three categories including (1) 3D model reconstruction, (2) geometry quality inspection, and (3) other applications. Following the literature review, this paper discusses on the acquisition and processing of point cloud data, particularly focusing on how to properly perform data acquisition and processing to fulfill the needs of the intended construction applications. Specifically, the determination of required point cloud data quality and the determination of data acquisition parameters are discussed with regard to data acquisition, and the extraction and utilization of semantic information and the platforms for data visualization and processing are discussed with regard to data processing. Based on the review of applications and the following discussions, research gaps and future research directions are recommended including (1) application-oriented data acquisition, (2) semantic enrichment for as-is BIM, (3) geometry quality inspection in fabrication phase, and (4) real-time visualization and processing.  相似文献   
999.
1000.
Stretchable and wearable sensor technology has attracted significant interests and created high technological impact on portable healthcare and smart human–machine interfaces. Wearable electromechanical systems are an important part of this technology that has recently witnessed tremendous progress toward high‐performance devices for commercialization. Over the past few years, great attention has been paid to simultaneously enhance the sensitivity and stretchability of the electromechanical sensors toward high sensitivity, ultra‐stretchability, low power consumption or self‐power functionalities, miniaturisation as well as simplicity in design and fabrication. This work presents state‐of‐the‐art advanced materials and rational designs of electromechanical sensors for wearable applications. Advances in various sensing concepts and structural designs for intrinsic stretchable conductive materials as well as advanced rational platforms are discussed. In addition, the practical applications and challenges in the development of stretchable electromechanical sensors are briefly mentioned and highlighted.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号