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   4891篇
  免费   304篇
  国内免费   21篇
电工技术   11篇
综合类   88篇
化学工业   472篇
金属工艺   14篇
机械仪表   98篇
建筑科学   100篇
矿业工程   11篇
能源动力   124篇
轻工业   3443篇
水利工程   42篇
石油天然气   453篇
武器工业   5篇
无线电   15篇
一般工业技术   180篇
冶金工业   33篇
原子能技术   30篇
自动化技术   97篇
  2024年   21篇
  2023年   69篇
  2022年   107篇
  2021年   204篇
  2020年   178篇
  2019年   125篇
  2018年   132篇
  2017年   227篇
  2016年   227篇
  2015年   223篇
  2014年   258篇
  2013年   321篇
  2012年   283篇
  2011年   327篇
  2010年   320篇
  2009年   316篇
  2008年   203篇
  2007年   263篇
  2006年   261篇
  2005年   196篇
  2004年   207篇
  2003年   158篇
  2002年   122篇
  2001年   89篇
  2000年   68篇
  1999年   76篇
  1998年   47篇
  1997年   34篇
  1996年   40篇
  1995年   21篇
  1994年   23篇
  1993年   13篇
  1992年   6篇
  1991年   6篇
  1990年   11篇
  1989年   3篇
  1988年   5篇
  1987年   8篇
  1986年   3篇
  1985年   10篇
  1984年   4篇
  1983年   1篇
排序方式: 共有5216条查询结果,搜索用时 15 毫秒
51.
Deep neural networks represent a compelling technique to tackle complex real-world problems, but are over-parameterized and often suffer from over- or under-confident estimates. Deep ensembles have shown better parameter estimations and often provide reliable uncertainty estimates that contribute to the robustness of the results. In this work, we propose a new metric to identify samples that are hard to classify. Our metric is defined as coincidence score for deep ensembles which measures the agreement of its individual models. The main hypothesis we rely on is that deep learning algorithms learn the low-loss samples better compared to large-loss samples. In order to compensate for this, we use controlled over-sampling on the identified ”hard” samples using proper data augmentation schemes to enable the models to learn those samples better. We validate the proposed metric using two public food datasets on different backbone architectures and show the improvements compared to the conventional deep neural network training using different performance metrics.  相似文献   
52.
While the availability of large-scale online recipe collections presents opportunities for health consumers to access a wide variety of recipes, it can be challenging for them to discover relevant recipes. Whereas most recommender systems are designed to offer selections consistent with users’ past behavior, it remains an open problem to offer selections that can help users’ transition from one type of behavior to another, intentionally. In this paper, we introduce health-guided recipe recommendation as a way to incrementally shift users towards healthier recipe options while respecting the preferences reflected in their past choices. Introducing a knowledge graph (KG) into recommender systems as side information has attracted great interest, but its use in recipe recommendation has not been studied. To fill this gap, we consider the task of recipe recommendation over knowledge graphs. In particular, we jointly learn recipe representations via graph neural networks over two graphs extracted from a large-scale Food KG, which capture different semantic relationships, namely, user preferences and recipe healthiness, respectively. To integrate the nutritional aspects into recipe representations and the recommendation task, instead of simple fusion, we utilize a knowledge transfer scheme to enable the transfer of useful semantic information across the preferences and healthiness aspects. Experimental results on two large real-world recipe datasets showcase our model’s ability to recommend tasty as well as healthy recipes to users.  相似文献   
53.
Truck scheduling at zero-inventory cross docking terminals   总被引:1,自引:0,他引:1  
Handling freight at cross docking terminals constitutes a complex planning task which comprises several executive steps as shipments delivered by inbound trucks are to be unloaded, sorted according to their designated destinations, moved across the dock and finally loaded onto outbound trucks for an immediate delivery elsewhere in the distribution system. To enable an efficient synchronization of inbound and outbound flows, a careful planning of operations, e.g. by computerized scheduling procedures, becomes indispensable. This work treats a special truck scheduling problem arising in the (zero-inventory) cross docks of the food industry, where strict cooling requirements forbid an intermediate storage inside the terminal, so that all products are to be instantaneously loaded onto refrigerated outbound trucks. The problem is formalized such that different operational objectives, i.e. the flow time, processing time and tardiness of outbound trucks, are minimized. To solve the resulting truck scheduling problem suited exact and heuristic solution procedures are presented.  相似文献   
54.
This paper addresses the food distribution decision from a wholesaler's perspective, as the wholesalers are often faced with thorny issues such as when, where, how to deliver products at the lowest costs to best satisfy the retailers’ changing needs. This research relies on a distribution problem encountered at Northern Grocery Company in Beijing as an example to develop a two-stage solution procedure and subsequent computer-enabled programs for identifying efficient vehicle routing alternatives. The solution process, which integrates heuristic search algorithms and an integer programming model, can be applied to a wide range of distribution problems with specified route durations and a circular transportation network structure as exemplified by City of Beijing.  相似文献   
55.
The Plasmodium falciparum food vacuole (FV) is a lysosome-like organelle where erythrocyte hemoglobin digestion occurs. It is a favorite target in the development of antimalarials. We have used a tandem mass spectrometry approach to investigate the proteome of an FV-enriched fraction and identified 116 proteins. The electron microscopy analysis and the Western blot data showed that the major component of the fraction was the FV and, as expected, the majority of previously known FV markers were recovered. Of particular interest, several proteins involved in vesicle-mediated trafficking were identified, which are likely to play a key role in FV biogenesis and/or FV protein trafficking. Recovery of parasite surface proteins lends support to the cytostomal pathway of hemoglobin ingestion as a FV trafficking route. We have identified 32 proteins described as hypothetical in the databases. This insight into FV protein content provides new clues towards understanding the biological function of this organelle in P. falciparum.  相似文献   
56.
Olli Varis 《国际水》2013,38(4):624-637
Abstract

The Nile brings virtually no water to the sea. The mighty basin with 1/10 of Africa's land area and 1/3 of its population, has only 1/16 of its water. The riparian countries use practically all of the Nile's water and they face increasing challenges in terms of environmental degradation, food security, and socioeconomic development. The geopolitical situation blocks the integrated development of water resources in the basin scale, yet the political environment may be improving. The Nile basin is among the most critical regions of the world in terms of water resources development. In this article, the trends of the major driving forces within the basin countries—population, urbanization, climate, agriculture, economy, human resources, and governance—are scrutinized from the viewpoint of their impacts on water resources and their management. A comparison is made to four other critical macroregions: China, South Asia, Southeast Asia, and West Africa.  相似文献   
57.
"国以民为本,民以食为天",食品安全事关国计民生。近期我国食品安全问题频繁发生,知名品牌卷入食品安全问题的漩涡之中。通过博弈分析,本文认为我国食品安全监管存在"激励悖论",建立和完善食品安全监管体系的三重约束和三道防线是解决我国食品安全问题的有效途径和重要手段。  相似文献   
58.
英国作家J.A.G.罗伯茨先生的《东食西渐》一书,是从一个真正意义上的西方人的视角,运用丰富翔实的英文书籍资料,包括一些珍贵的历史图片撰写而成,而且这些资料在中国国内几乎是找不到的。他从一个生活在中国本土的中国学者无法做到的研究角度,对中国饮食文化自18世纪以来在西方的传播渗透与普及流行进行了深度的介绍与揭示。其深远的文化意义与历史贡献是不言而喻的。  相似文献   
59.
淮扬饮食文化景观谱系的构建是深度挖掘整理淮扬菜文化基因,形成系统保护与传承体系的基础性工作.在对旅游景观谱系相关研究进行系统梳理的基础上,将饮食文化景观谱系的结构分为景观元、景观点和景观走廊三个层次,结合文献分析和专家意见,构建淮扬饮食文化景观谱系.淮扬饮食文化景观谱系对促进城市旅游资源的深度开发、促进旅游产品内涵拓展具有重要作用,对推进城市旅游转型和推广城市旅游形象等方面也具有重要的价值.  相似文献   
60.
Sensory evaluation is the application of knowledge and skills derived from several different scientific and technical disciplines, physiology, chemistry, mathematics and statistics, human behavior, and knowledge about product preparation practices. This research was aimed to evaluate aftertaste sensory attributes of commercial non-alcoholic beer brands (P1, P2, P3, P4, P5, P6, P7) by several chemometric tools. These attributes were bitter, sour, sweet, fruity, liquorice, artificial, body, intensity and duration. The results showed that the data are in a good consistency. Therefore, the brands were statistically classified in several categories. Linear techniques as Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were performed over the data that revealed all types of beer are well separated except a partial overlapping between zones corresponding to P4, P6 and P7. In this research, for the confirmation of the groups observed in PCA and in order to calculate the errors in calibration and in validation, PLS-DA technique was used. Based on the quantitative data of PLS-DA, the classification accuracy values were ranked within 49-86%. Moreover, it was found that the classification accuracy of LDA was much better than PCA. It shows that this trained sensory panel can discriminate among the samples except an overlapping between two types of beer. Also, two types of artificial networks were used: Probabilistic Neural Networks (PNN) with Radial Basis Functions (RBF) and FeedForward Networks with Back Propagation (BP) learning method. The highest classification success rate (correct predicted number over total number of measurements) of about 97% was obtained for RBF followed by 94% for BP. The results obtained in this study could be used as a reference for electronic nose and electronic tongue in beer quality control.  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