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   659篇
  免费   43篇
  国内免费   26篇
电工技术   34篇
综合类   122篇
化学工业   79篇
金属工艺   8篇
机械仪表   22篇
建筑科学   34篇
矿业工程   6篇
能源动力   5篇
轻工业   115篇
水利工程   2篇
武器工业   3篇
无线电   40篇
一般工业技术   34篇
冶金工业   104篇
原子能技术   6篇
自动化技术   114篇
  2024年   3篇
  2023年   9篇
  2022年   26篇
  2021年   60篇
  2020年   27篇
  2019年   27篇
  2018年   18篇
  2017年   20篇
  2016年   23篇
  2015年   15篇
  2014年   43篇
  2013年   37篇
  2012年   49篇
  2011年   51篇
  2010年   20篇
  2009年   41篇
  2008年   38篇
  2007年   43篇
  2006年   33篇
  2005年   22篇
  2004年   22篇
  2003年   25篇
  2002年   15篇
  2001年   17篇
  2000年   8篇
  1999年   5篇
  1998年   3篇
  1997年   6篇
  1996年   6篇
  1995年   1篇
  1994年   1篇
  1992年   1篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1985年   2篇
  1983年   1篇
  1980年   1篇
  1965年   1篇
排序方式: 共有728条查询结果,搜索用时 140 毫秒
11.
Advances in the field of medical sciences and medical technology, and present-day challenges, such as an aging population, rising medical expenses, and lifestyle-related diseases, have collectively catalyzed a research ecosystem termed “smart wellness.” This article describes the establishment of a smart wellness service platform designed to empower individuals to create a sense of balance in their lives. Step-by-step details include service model, design, and architectural considerations. As a proof of concept, implementation details of a Health Improvement and Management Systems (HIMS) Hub, a Smart Wellness Service Platform deployed in six cities in South Korea, are presented. An on-site survey conducted in Busan Metropolitan City reveals the percentage of satisfied users to be 91.3%. Furthermore, data gathered from 27,236 physical evaluations of users from a Busan city center over the period of April 2013 to May 2018 reveal that males and females in their 50s and 60s account for the highest number of participants, while males in their 70s have a higher rate of participation than females in the same age group.  相似文献   
12.
Humans spend approximately 90% of their time indoors, impacting their own air quality through occupancy and activities. Human VOC emissions indoors from exercise are still relatively uncertain, and questions remain about emissions from chlorine-based cleaners. To investigate these and other issues, the ATHLETic center study of Indoor Chemistry (ATHLETIC) campaign was conducted in the weight room of the Dal Ward Athletic Center at the University of Colorado Boulder. Using a Vocus Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (Vocus PTR-TOF), an Aerodyne Gas Chromatograph (GC), an Iodide-Chemical Ionization Time-of-Flight Mass Spectrometer (I-CIMS), and Picarro cavity ringdown spectrometers, we alternated measurements between the weight room and supply air, allowing for determination of VOC, NH3, H2O, and CO2 emission rates per person (emission factors). Human-derived emission factors were higher than previous studies of measuring indoor air quality in rooms with individuals at rest and correlated with increased CO2 emission factors. Emission factors from personal care products (PCPs) were consistent with previous studies and typically decreased throughout the day. In addition, N-chloraldimines were observed in the gas phase after the exercise equipment was cleaned with a dichlor solution. The chloraldimines likely originated from reactions of free amino acids with HOCl on gym surfaces.  相似文献   
13.
耙矿绞车传动系统是决定整个绞车性能的主要因素,所以对齿轮进行优化设计,选定其最佳参数是提高耙矿绞车的承载力,减小体积,降低成本等多项指标的重要举措,以行星齿轮为例,建立耙矿绞车齿轮传动结构优化设计的数学模型,在满足各项功能的条件下,最大幅度地减小绞车齿轮传动系统的体积,降低其生产成本。  相似文献   
14.
郑瑾华  刘军 《规划师》2006,22(Z1):30-32
为配合全民健身计划,河源市在新建的文化广场中,利用体育馆及其周边场地规划以全民健身为主题的园林式休闲健身活动空间.休闲健身区规划设计以文化广场主轴和水系为依托形成景观轴线,根据运动激烈程度和人们的不同需求划分功能区,并采用"S"型构图将各功能区串联,利用西面游园的水系,形成江河水-人工湖-景观水-江河水的循环利用,凸显河源市的"水"特色.  相似文献   
15.
杜钧 《山西建筑》2003,29(11):6-7
介绍了居住区老龄人活动区的设计 ,阐述了住区老龄人活动区的建筑设置形式及内容 ,指出老龄人活动区设计要根据老年人的特点 ,体现“夕阳无限好”的主题。  相似文献   
16.
Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in industrialized countries. The increasing prevalence of NAFLD mirrors the outbreak of obesity in western countries, highlighting the connection between these two conditions. Nevertheless, there is currently no specific pharmacotherapy for its treatment. Accepted management begins with weight loss and exercise. Moreover, exercise can provide metabolic benefits independently of weight loss. It is known how long-term aerobic training produces improvements in hepatic triglycerides, visceral adipose tissue and free fatty acids, even if there is no weight reduction. A recent study from Boström et al. unravels a potential molecular mechanism that may explain how exercise, independently of weight loss, can potentially improve metabolic parameters through a new messenger system (irisin) linking muscle and fat tissue. Irisin has been proposed to act as a hormone on subcutaneous white fat cells increasing energy expenditure by means of a program of brown-fat-like development. Moreover, it was also shown that irisin plasma concentration was higher in people who exercise, suggesting a molecular mechanism by which exercise may improve metabolism. The present systematic review is based on the possibility that irisin might represent a hypothetical connection between NAFLD pathogenesis and disease progression.  相似文献   
17.
Endogenous neural stem/progenitor cells (eNSPCs) proliferate and differentiate into neurons and glial cells after spinal cord injury (SCI). We have previously shown that melatonin (MT) plus exercise (Ex) had a synergistic effect on functional recovery after SCI. Thus, we hypothesized that combined therapy including melatonin and exercise might exert a beneficial effect on eNSPCs after SCI. Melatonin was administered twice a day and exercise was performed on a treadmill for 15 min, six days per week for 3 weeks after SCI. Immunohistochemistry and RT-PCR analysis were used to determine cell population for late response, in conjunction with histological examination and motor function test. There was marked improvement in hindlimb function in SCI+MT+Ex group at day 14 and 21 after injury, as documented by the reduced size of the spinal lesion and a higher density of dendritic spines and axons; such functional improvements were associated with increased numbers of BrdU-positive cells. Furthermore, MAP2 was increased in the injured thoracic segment, while GFAP was increased in the cervical segment, along with elevated numbers of BrdU-positive nestin-expressing eNSPCs in the SCI+MT+Ex group. The dendritic spine density was augmented markedly in SCI+MT and SCI+MT+Ex groups. These results suggest a synergistic effect of SCI+MT+Ex might create a microenvironment to facilitate proliferation of eNSPCs to effectively replace injured cells and to improve regeneration in SCI.  相似文献   
18.
19.
20.
In 1937, Sir H. A Krebs first published the Citric Acid Cycle, a unidirectional cycle with carboxylic acids. The original concept of the Citric Acid Cycle from Krebs’ 1953 Nobel Prize lecture illustrates the unidirectional degradation of lactic acid to water, carbon dioxide and hydrogen. Here, we add the heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex, connecting the original Citric Acid Cycle to the flow of energy and material. The heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex catalyses the first reaction of the Citric Acid Cycle, the oxidation of lactate to pyruvate, and thus secures the provision of pyruvic acid. In addition, we modify Krebs’ original concept by feeding the cycle with oxaloacetic acid. Our concept enables the integration of anabolic processes and allows adaption of the organism to recover ATP faster.  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