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   7040篇
  免费   327篇
  国内免费   26篇
电工技术   120篇
综合类   8篇
化学工业   1499篇
金属工艺   139篇
机械仪表   156篇
建筑科学   228篇
矿业工程   13篇
能源动力   224篇
轻工业   535篇
水利工程   54篇
石油天然气   27篇
无线电   1110篇
一般工业技术   1253篇
冶金工业   919篇
原子能技术   65篇
自动化技术   1043篇
  2023年   104篇
  2022年   186篇
  2021年   288篇
  2020年   227篇
  2019年   196篇
  2018年   246篇
  2017年   198篇
  2016年   295篇
  2015年   184篇
  2014年   255篇
  2013年   430篇
  2012年   315篇
  2011年   367篇
  2010年   275篇
  2009年   260篇
  2008年   276篇
  2007年   264篇
  2006年   199篇
  2005年   177篇
  2004年   149篇
  2003年   130篇
  2002年   118篇
  2001年   118篇
  2000年   88篇
  1999年   107篇
  1998年   351篇
  1997年   171篇
  1996年   151篇
  1995年   122篇
  1994年   87篇
  1993年   120篇
  1992年   80篇
  1991年   84篇
  1990年   46篇
  1989年   75篇
  1988年   59篇
  1987年   55篇
  1986年   53篇
  1985年   51篇
  1984年   54篇
  1983年   45篇
  1982年   39篇
  1981年   40篇
  1980年   30篇
  1979年   25篇
  1978年   26篇
  1977年   25篇
  1976年   42篇
  1974年   17篇
  1971年   13篇
排序方式: 共有7393条查询结果,搜索用时 15 毫秒
91.
As with other forms of stress, surgery is a time of fluctuating haemodynamics, physiological shifts, intense metabolic changes, and protein catabolism and anabolism. At times, these changes can occur within hours. There is a reasonable body of literature concerning the adverse effects of surgery on gastric emptying, but not on the effects of surgery on the distribution, metabolism and excretion of drugs. Gastric emptying is diminished or absent following major procedures, which prevent the delivery of orally administered drugs to their major site of absorption, the small bowel. Changes in the paracellular absorption of drugs may occur postoperatively, although transcellular absorption appears to be unimpaired. Distribution is affected by changes in blood volume, alterations in circulation, increases in the extracellular fluid and changes in the circulating plasma protein levels, such as albumin and alpha 1-acid glycoprotein. Little is known about alterations in drug metabolism following surgery. However, it has been shown that systemic hypoxia alters the function of some of the cytochrome P450 (CYP) system and increased levels of cytokines have an effect on the metabolism of at least 1 drug. In addition, the renal elimination of drugs is affected in patients postoperatively, although the effects of biliary clearance in this period are difficult to determine. Despite the lack of research into pharmacokinetics during the postoperative period, and given the immense and often sudden changes observed in patients post-surgery, it is reasonable to recommend vigilance with respect to drug therapy during this period.  相似文献   
92.

Shear connectors play a prominent role in the design of steel-concrete composite systems. The behavior of shear connectors is generally determined through conducting push-out tests. However, these tests are costly and require plenty of time. As an alternative approach, soft computing (SC) can be used to eliminate the need for conducting push-out tests. This study aims to investigate the application of artificial intelligence (AI) techniques, as sub-branches of SC methods, in the behavior prediction of an innovative type of C-shaped shear connectors, called Tilted Angle Connectors. For this purpose, several push-out tests are conducted on these connectors and the required data for the AI models are collected. Then, an adaptive neuro-fuzzy inference system (ANFIS) is developed to identify the most influencing parameters on the shear strength of the tilted angle connectors. Totally, six different models are created based on the ANFIS results. Finally, AI techniques such as an artificial neural network (ANN), an extreme learning machine (ELM), and another ANFIS are employed to predict the shear strength of the connectors in each of the six models. The results of the paper show that slip is the most influential factor in the shear strength of tilted connectors and after that, the inclination angle is the most effective one. Moreover, it is deducted that considering only four parameters in the predictive models is enough to have a very accurate prediction. It is also demonstrated that ELM needs less time and it can reach slightly better performance indices than those of ANN and ANFIS.

  相似文献   
93.
Knowledge and Information Systems - With the advance of information technology, many fields have begun using data clustering to reveal data structures and obtain useful information. Most of the...  相似文献   
94.
Engineering with Computers - The advent of new data-mining techniques and, more recently, swarm-based optimization algorithms have antiquated traditional models in the field of energy performance...  相似文献   
95.
Production scheduling involves all activities of building production schedules, including coordinating and assigning activities to each person, group of people, or machine and arranging work orders in each workplace. Production scheduling must solve all problems such as minimizing customer wait time, storage costs, and production time; and effectively using the enterprise’s human resources. This paper studies the application of flexible job shop modelling on scheduling a woven labelling process. The labelling process includes several steps which are handled in different work-stations. Each workstation is also comprised of several identical parallel machines. In this study, job splitting is allowed so that the power of work stations can be utilized better. The final objective is to minimize the total completion time of all jobs. The results show a significant improvement since the new planning may save more than 60% of lead time compared to the current schedule. The contribution of this research is to propose a flexible job shop model for scheduling a woven labelling process. The proposed approach can also be applied to support complex production scheduling processes under fuzzy environments in different industries. A practical case study demonstrates the effectiveness of the proposed model.  相似文献   
96.

Due to the budget and environmental issues, adaptive energy efficiency receives a lot of attention these days, especially for cloud computing. In the previous research, we developed a combined methodology based on nonparametric prediction and convex optimization to produce proactive energy efficiency-oriented solution. In this work, the predictive analysis was further enhanced by deriving the mixture power spectral density to model the complex cloud monitoring statistics. By engaging the improved technique to the predictive analysis, the prediction process was more adaptive to handle the fluctuation in system utilization. As a consequence, the optimization process could subsequently produce more appropriate setting for energy savings. After the infrastructure setting has been made available, the instruction of virtual machine migration was created and implemented by the cloud orchestrator. This instruction condensed the services into the pool of active facilities, satisfying the objective of power efficiency. Eventually, any physical machine out of the power configuration would be gradually terminated. Compared to our former method, the effectiveness of the proposed technique has been proven by cutting down 4.92% of energy consumption, while still maintaining a similar quality of services.

  相似文献   
97.
The Journal of Supercomputing - In this study, we present a fusion model for emotion recognition based on visual data. The proposed model uses video information as its input and generates emotion...  相似文献   
98.
Vo  Minh Thanh  Nguyen  Trang  Vo  H. Anh  Le  Tuong 《Applied Intelligence》2021,51(11):7827-7836
Applied Intelligence - In the field of supervised learning, the problem of class imbalance is one of the most difficult problems, and has attracted a great deal of research attention in recent...  相似文献   
99.
Particle swarm optimization (PSO) has been shown as an effective tool for solving global optimization problems. So far, most PSO algorithms use a single learning pattern for all particles, which means that all particles in a swarm use the same strategy. This monotonic learning pattern may cause the lack of intelligence for a particular particle, which makes it unable to deal with different complex situations. This paper presents a novel algorithm, called self-learning particle swarm optimizer (SLPSO), for global optimization problems. In SLPSO, each particle has a set of four strategies to cope with different situations in the search space. The cooperation of the four strategies is implemented by an adaptive learning framework at the individual level, which can enable a particle to choose the optimal strategy according to its own local fitness landscape. The experimental study on a set of 45 test functions and two real-world problems show that SLPSO has a superior performance in comparison with several other peer algorithms.  相似文献   
100.
Cloud computing services have recently become a ubiquitous service delivery model, covering a wide range of applications from personal file sharing to being an enterprise data warehouse. Building green data center networks providing cloud computing services is an emerging trend in the Information and Communication Technology (ICT) industry, because of Global Warming and the potential GHG emissions resulting from cloud services. As one of the first worldwide initiatives provisioning ICT services entirely based on renewable energy such as solar, wind and hydroelectricity across Canada and around the world, the GreenStar Network (GSN) was developed to dynamically transport user services to be processed in data centers built in proximity to green energy sources, reducing Greenhouse Gas (GHG) emissions of ICT equipments. Regarding the current approach, which focuses mainly in reducing energy consumption at the micro-level through energy efficiency improvements, the overall energy consumption will eventually increase due to the growing demand from new services and users, resulting in an increase in GHG emissions. Based on the cooperation between Mantychore FP7 and the GSN, our approach is, therefore, much broader and more appropriate because it focuses on GHG emission reductions at the macro-level. This article presents some outcomes of our implementation of such a network model, which spans multiple green nodes in Canada, Europe and the USA. The network provides cloud computing services based on dynamic provision of network slices through relocation of virtual data centers.  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