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   683篇
  免费   43篇
  国内免费   1篇
电工技术   8篇
化学工业   154篇
金属工艺   8篇
机械仪表   12篇
建筑科学   31篇
矿业工程   1篇
能源动力   24篇
轻工业   77篇
水利工程   3篇
石油天然气   3篇
无线电   65篇
一般工业技术   125篇
冶金工业   64篇
原子能技术   4篇
自动化技术   148篇
  2023年   11篇
  2022年   18篇
  2021年   35篇
  2020年   25篇
  2019年   18篇
  2018年   36篇
  2017年   23篇
  2016年   27篇
  2015年   18篇
  2014年   39篇
  2013年   50篇
  2012年   45篇
  2011年   48篇
  2010年   29篇
  2009年   41篇
  2008年   38篇
  2007年   37篇
  2006年   28篇
  2005年   22篇
  2004年   16篇
  2003年   18篇
  2002年   18篇
  2001年   10篇
  2000年   6篇
  1999年   6篇
  1998年   10篇
  1997年   5篇
  1996年   8篇
  1995年   4篇
  1994年   1篇
  1993年   6篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1986年   3篇
  1985年   3篇
  1984年   5篇
  1983年   4篇
  1980年   1篇
  1979年   1篇
  1976年   2篇
  1975年   2篇
  1969年   1篇
排序方式: 共有727条查询结果,搜索用时 31 毫秒
721.

Introduction

Hemodialysis (HD) induces several physiological changes that can affect plasma glucose levels in patients with diabetes and in turn their glycemic control. Studies using continuous glucose monitoring (CGM) to assess glucose variations on dialysis days compared with nondialysis days report conflicting results. Here, we used CGM to examine glucose variations induced by HD in patients with type 2 diabetes.

Methods

Patients with type 2 diabetes undergoing maintenance HD were included. CGM (Ipro2®, Medtronic) was performed at baseline and Week 4, 8, 12, and 16 for up to 7 days at each visit. CGM profiles on days where participants received HD were compared with days without HD using a linear mixed model.

Findings

Twenty-seven patients were included. The median number of CGM days performed was 8 (interquartile range [IQR] 6–10) for dialysis days and 16 (IQR 12–17) for nondialysis days. The median sensor glucose was 9.4 (95% confidence interval [CI] 8.8–10.2) mmol/L on dialysis days compared with 9.5 (95% CI 8.9–10.2) mmol/L on nondialysis days (p = 0.58). Nocturnal mean sensor glucose was higher on dialysis days compared with nondialysis days: 8.8 (95% CI 8.0–9.6) mmol/L versus 8.4 (95% CI 7.7–9.2) mmol/L (p = 0.029).

Discussion

Similar median sensor glucose values were found for days on and off HD. Nocturnal glucose levels were modestly increased on dialysis days. Our findings indicate that antidiabetic treatment does not need to be differentiated on dialysis versus nondialysis days in patients with type 2 diabetes undergoing maintenance HD.  相似文献   
722.
Poly(lactic acid)/poly(butylene succinate-co-adipate) (PLA/PBSA) blends are found promising for film packaging applications because of their flexibility, resistance, and compostability. Industrially extruded granules and films based on PLA and containing different amounts of PBSA are reprocessed through mini-extrusion, to simulate recycling, and tested in terms of their melt flow rate as a function of PBSA content. Moreover, pure PLA commercial granules and the film produced extruding the PLA/PBSA 60/40 blend are reprocessed several times by injection molding and characterized in terms of melt flow rate, mechanical properties, thermal properties, and color as a function of injection molding cycles. The variation in melt fluidity and thermo-mechanical properties is negligible up to 3 injection molding cycles for both pure PLA granules and PLA/PBSA blend. In the case of blend the change in color (yellowing and darkening) is more evident and slight local compositional change in injection molded items can be evidenced as well as a slight decrease in PBS crystallinity as a function of injection molding cycles. Nevertheless, in applications where these aspects are not critical, these materials can be recycled by extrusion or injection molding before being composted, thus prolonging their life cycle and storing carbon in them as longer as possible.  相似文献   
723.
A software-based measurement system using both analogue data acquisition and digital communication via a general-purpose interface bus (GPIB) board has been developed for analysis and evaluation of disc brake squeal. The system is built around a computer and based on commercial software. Brake pressure and torque, rotational speed, five different temperatures, and sound emission are logged once a second. If the sound is characterised as a squeal it is saved to file together with the other parameters. The measurement system is very flexible, allowing for different types of instruments and sensors to be used by adapting the software. Furthermore, the same software is used for evaluation of the collected data. Mechanically, the equipment consists of a complete front wheel suspension where the original brake disc and caliper are mounted in a steel tube chassis. The brake disc is driven by a DC electric motor, while a hydraulic system provides the brake pressure. Brake pressure and rotational speed can be controlled independently.  相似文献   
724.
725.
Magnetohydrodynamic mixing was evaluated as an alternative to conventional high shear mixing (HSM) in the preparation of carbomer hydrogels containing 1.22 wt% Carbopol® 980 NF. Neutralization of the carbomer dispersion (pH = 2.74) with triethanolamine (TEA) enabled to adjust the pH of the mixture and tune the viscosity of the hydrogel. Using HSM, this approach was limited to 0.2 wt% TEA (pH = 3.83) as the gel became too viscous and the recirculation flow dropped from 12 to 0.3 m3/h. Magnetohydrodynamic mixing enabled to reach TEA concentrations up to 1.0 wt% (pH = 5.31). Apparent viscosity measurements on samples having 0.2 wt% TEA revealed lower viscosities for carbomer hydrogels prepared with HSM, that is, 6800 mPa s versus 8800 mPa for magneto-hydrodynamic mixing. Based on 1H NMR evidence, this decrease in apparent viscosity was attributed to structural damage to the carbomer backbone in combination with mechanochemical degradation of the added TEA.  相似文献   
726.
A series of 19 ionic liquids (ILs) based on phosphonium and imidazolium cations of varying alkyl-chain lengths with the orthoborate anions bis(oxalato)borate [BOB], bis(mandelato)borate, [BMB] and bis(salicylato)borate, [BScB], are synthesized and studied using small-angle neutron scattering (SANS). All measured systems display nanostructuring, with 1-methyl-3-n-alkyl imidazolium-orthoborates forming clearly bicontinuous L3 spongelike phases when the alkyl chains are longer than C6 (hexyl). L3 phases are fitted using the Teubner and Strey model, and diffusely-nanostructured systems are primarily fitted using the Ornstein-Zernicke correlation length model. Strongly-nanostructured systems have a strong dependence on the cation, with molecular architecture variation explored to determine the driving forces for self-assembly. The ability to form well-defined complex phases is effectively extinguished in several ways: methylation of the most acidic imidazolium ring proton, replacing the imidazolium 3-methyl group with a longer hydrocarbon chain, substitution of [BOB] by [BMB], or exchanging the imidazolium for phosphonium systems, irrespective of phosphonium architecture. The results suggest there is only a small window of opportunity, in terms of molecular amphiphilicity and cation:anion volume matching, for the formation of stable extensive bicontinuous domains in pure bulk orthoborate-based ILs. Particularly important for self-assembly processes appear to be the ability to form H-bonding networks, which offer additional versatility in imidazolium systems.  相似文献   
727.
Hot‐pressed, laboratory‐made, ZrO2‐based composites with 40 vol. % WC, TiCN or TiN were surface finished by electrical discharge machining in order to compare their reciprocating sliding friction and wear response against WC–6wt%Co cemented carbide in unlubricated conditions. Sliding experiments were performed using a Plint TE77 pin‐on‐flat wear test rig, revealing a strong impact of the secondary phase on the tribological behaviour of the ZrO2‐based composites. The worn surfaces and wear debris were characterised by scanning electron microscopy, energy dispersive X‐ray analysis and surface topography scanning, pointing out abrasion, polishing and adhesion as main wear mechanisms. The most favourable friction and wear characteristics were encountered with ZrO2–WC composites compared to the other grades with equal amount of volumetric secondary phase. Copyright © 2009 John Wiley & Sons, Ltd.  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