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   345篇
  免费   12篇
电工技术   10篇
化学工业   54篇
金属工艺   13篇
机械仪表   9篇
建筑科学   11篇
能源动力   9篇
轻工业   19篇
水利工程   1篇
石油天然气   1篇
无线电   48篇
一般工业技术   99篇
冶金工业   25篇
原子能技术   3篇
自动化技术   55篇
  2023年   4篇
  2022年   8篇
  2021年   15篇
  2020年   10篇
  2019年   8篇
  2018年   18篇
  2017年   13篇
  2016年   14篇
  2015年   5篇
  2014年   6篇
  2013年   40篇
  2012年   19篇
  2011年   25篇
  2010年   18篇
  2009年   18篇
  2008年   23篇
  2007年   15篇
  2006年   12篇
  2005年   7篇
  2004年   6篇
  2003年   6篇
  2002年   6篇
  2001年   2篇
  2000年   4篇
  1999年   5篇
  1998年   2篇
  1997年   2篇
  1996年   2篇
  1995年   8篇
  1994年   6篇
  1993年   4篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1987年   1篇
  1985年   3篇
  1984年   2篇
  1983年   5篇
  1982年   2篇
  1981年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1974年   2篇
  1973年   2篇
排序方式: 共有357条查询结果,搜索用时 15 毫秒
1.
Devi  Neena  Patel  Sanjay K. S.  Kumar  Pradeep  Singh  Archana  Thakur  Nandita  Lata  Jeevan  Pandey  Deepak  Thakur  Vikram  Chand  Duni 《Catalysis Letters》2022,152(4):944-953
Catalysis Letters - In this study, Rhodococcus pyridinivorans cells containing hyperactive acyltransferase was immobilized on various macromolecules based-polymeric matrices and used to improve...  相似文献   
2.
Sudden cardiac death (SCD) is reported as leading cause of death in patients on chronic hemodialysis. Arrhythmias are proposed to be a major predisposing factor for SCD. However, triggers for potentially lethal arrhythmias are not well understood. Here we describe a case of 72‐year‐old man on chronic hemodialysis via permanent Central venous catheter (CVC) who was admitted for evaluation after unwitnessed fall. Within 10 minutes of his first routine dialysis session in the hospital, he had cardiac‐arrest. He was successfully resuscitated within 3 minutes. The next day, fifteen minutes into the dialysis session, he had bradycardia with telemetry demonstrating long sinus pause and he lost consciousness. After few minutes of Advanced Cardiac Life Support (ACLS) he regained pulse and consciousness. Further review of the chest X‐ray revealed the tip of CVC to be directly touching the distal Superior Vena Cava (SVC) wall. We felt the catheter tip may have migrated after the fall and now is irritating the Sinoatrial node and triggering bradyarrhythmia. Next day, the CVC was exchanged, and the tip was placed higher up in superior vena‐cava. After repositioning, we started him on dialysis under intensive monitoring, and he tolerated well without any arrhythmia. Subsequent dialysis was uneventful. We describe a case of recurrent symptomatic intra‐dialytic bradycardia due to abnormal positioning of CVC that resolved after the repositioning of the catheter. This case in addition to similar case in nondialysis settlings provides additional insights into mechanisms of fatal arrhythmias in hemodialysis patient having CVC.  相似文献   
3.
Lifetime prediction of polymer–polymer contacts is a major challenge. Current design methods stemming from metal contact surfaces lack accuracy because polymers behave differently, especially regarding temperature variations. Experiments were performed on a pin-on-disk setup alternating static and rotating elements. Common unfilled engineering polymers, viz. polyoxymethylene (POM), polypropylene (PP), polyamide 6.6 (PA6.6), and polycarbonate (PC) were tested at ambient and elevated temperatures. Material combinations were analyzed regarding the effects of load, velocity, temperature, and the product of contact pressure and sliding velocity (PV limit). The experimental results show that the PV limit is not predictive for polymer–polymer contacts; rather, each material combination has a critical factor that determines the wear and frictional values and thus the contact’s durability and lifetime. The critical factor is the value of contact pressure or sliding velocity or temperature at which there is sudden increase in wear rate. The experimental results also demonstrate that the application temperature in operation has an important influence on the lifetime. A temperature increase can either be beneficial or have a negative impact depending on the material combination. Resulting from the extensive experimental analysis, a new design method, based on the principle of deformation energy, is proposed. The new model is different from existing models because it includes thermal properties of the materials in contact and it makes use of the Péclet number. Because the proposed model requires only data sheet values and design parameters to predict wear volume, the model improves the support of engineers in designing durable polymer–polymer sliding contacts.  相似文献   
4.
Verma  Amit  Dawar  Siddharth  Kumar  Raman  Navathe  Shamkant  Goyal  Vikram 《Applied Intelligence》2021,51(7):4649-4663

High-utility Itemset Mining (HUIM) finds patterns from a transaction database with their utility no less than a user-defined threshold. The utility of an itemset is defined as the sum of the utilities of its items. The utility notion enables a data analyst to associate a profit score with each item and thereof to a pattern. We extend the notion of high-utility with diversity to define a new pattern type called High-utility and Diverse pattern (HUD). The notion of diversity of a pattern captures the extent of the different categories covered by the selected items in the pattern. An application of diverse-pattern lies in the recommendation task where a system can recommend to a customer a set of items from a new class based on her previously bought items. Our notion of diversity is easy to compute and also captures the basic essence of a previously proposed diversity notion. The existing algorithm to compute frequent-diverse patterns is 2-phase, i.e., in the first phase, frequent patterns are computed, out of which diverse patterns are filtered out in the second phase. We, in this paper, give an integrated algorithm that efficiently computes high-utility and diverse patterns in a single phase. Our experimental study shows that our proposed algorithm is very efficient as compared to a 2-phase algorithm that extracts high-utility itemsets in the first phase and filters out the diverse itemsets in the second phase.

  相似文献   
5.
6.

High nitrogen steels provide excellent mechanical properties and corrosion resistance but are prone to form precipitates which adversely affect the corrosion resistance and toughness. High nitrogen steel powders currently available in the market are not claimed to be precipitate free. It is critical to avoid these precipitates while retaining nitrogen in the dissolved form to realize the value of these powder alloys. However, retaining high level of dissolved nitrogen in steel powder during melt atomization process is very challenging. Instead, solid-state dissolution of nitrogen into the powder alloy followed by rapid cooling may provide a convenient approach to avoid precipitate formation compared to traditional melt processing. This study presents a solution treatment approach to achieve elevated dissolved nitrogen levels (~ 0.4 wt pct) in Fe–Mn–Cr powder alloy with negligible precipitation of nitrides. The influence of starting material, holding time, temperature and cooling rate on the resulting microstructure is presented. A fully austenite matrix with high dissolved nitrogen content resulted in powders with desired mechanical properties.

  相似文献   
7.
8.
9.
10.
Neural Computing and Applications - Recently established Harris Hawks optimization (HHO) has natural behaviour for finding an optimum solution in global search space without getting trapped in...  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