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   2674篇
  免费   195篇
  国内免费   1篇
电工技术   56篇
综合类   1篇
化学工业   776篇
金属工艺   17篇
机械仪表   80篇
建筑科学   104篇
矿业工程   2篇
能源动力   83篇
轻工业   424篇
水利工程   27篇
石油天然气   5篇
无线电   233篇
一般工业技术   387篇
冶金工业   105篇
原子能技术   12篇
自动化技术   558篇
  2023年   24篇
  2022年   19篇
  2021年   182篇
  2020年   90篇
  2019年   84篇
  2018年   109篇
  2017年   84篇
  2016年   135篇
  2015年   90篇
  2014年   117篇
  2013年   201篇
  2012年   169篇
  2011年   218篇
  2010年   153篇
  2009年   181篇
  2008年   125篇
  2007年   129篇
  2006年   112篇
  2005年   87篇
  2004年   66篇
  2003年   57篇
  2002年   61篇
  2001年   35篇
  2000年   28篇
  1999年   23篇
  1998年   40篇
  1997年   24篇
  1996年   30篇
  1995年   16篇
  1994年   30篇
  1993年   10篇
  1992年   11篇
  1991年   5篇
  1990年   17篇
  1989年   11篇
  1988年   11篇
  1987年   6篇
  1986年   4篇
  1985年   5篇
  1984年   12篇
  1983年   9篇
  1982年   10篇
  1981年   6篇
  1980年   11篇
  1977年   3篇
  1976年   2篇
  1975年   2篇
  1971年   2篇
  1965年   2篇
  1909年   2篇
排序方式: 共有2870条查询结果,搜索用时 78 毫秒
151.
152.
In this work platelet lysate (PL) and adipose‐derived mesenchymal stromal cells (ASCs) seeded on nonwoven fibroin mats were in vitro and in vivo evaluated for tissue regenerative applications. Nonwoven mats obtained by a large scale water entanglement technique were characterized for their physico‐chemical properties. Results indicated a high purity of fibroin fibers, their stability after sterilization process and appropriate technological properties suitable for tissue engineering. Moreover, the scaffolds in vitro supported adhesion and migration of ASCs and the presence of PL improved the cell proliferation. The products were then applied on epithelial/dermal wounds carried out on the dorsal surface of rabbit: the skin reparative process was solved in 9 days, with a completely restitutio ad integrum of the epithelium in animals treated with PL alone; ASCs did not further improve the wound healing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42942.  相似文献   
153.
Osteoarthritis is the most common human arthritis characterized by degeneration of articular cartilage. Several studies reported that levels of human cartilage glycoprotein chitinase 3-like-1 (CHI3L1) are known as a potential marker for the activation of chondrocytes and the progression of Osteoarthritis (OA), whereas lubricin appears to be chondroprotective. The aim of this study was to investigate the co-expression and co-localization of CHI3L1 and lubricin in normal and osteoarthritic rat articular cartilage to correlate their modified expression to a specific grade of OA. Samples of normal and osteoarthritic rat articular cartilage were analyzed by the Kellgren–Lawrence OA severity scores, the Kraus’ modified Mankin score and the Histopathology Osteoarthritis Research Society International (OARSI) system for histomorphometric evaluations, and through CHI3L1 and lubricin gene expression, immunohistochemistry and double immuno-staining analysis. The immunoexpression and the mRNA levels of lubricin increased in normal cartilage and decreased in OA cartilage (normal vs. OA, p < 0.01). By contrast, the immunoexpression and the mRNA levels of CHI3L1 increased in OA cartilage and decreased in normal cartilage (normal vs. OA, p < 0.01). Our findings are consistent with reports suggesting that these two glycoproteins are functionally associated with the development of OA and in particular with grade 2/3 of OA, suggesting that in the future they could be helpful to stage the severity and progression of the disease.  相似文献   
154.
In the last few years, a new class of smart multifunctional photoelectrochemical devices has been attracting the interest of several academic institutions and industrial companies: photovoltachromic cells, combining the features of photoelectrochromic cells with those of dye‐sensitized solar cells. Here, we report the results of a detailed electrochemical analysis aiming at investigating the electrochemical behavior of these complex photoelectrochemical devices. In particular, we have been focused on the effect of Li+ ions displacement during the coloration of the electrochromic tungsten oxide on the performances of the photovoltaic unit. As we had previously observed striking differences between the performances of the barely photovoltaic mode (with the tungsten oxide in the bleached state) and the photovoltachromic mode (with the tungsten oxide in the colored state), we thus attempted to provide a reasonable physical interpretation to the observed phenomena. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
155.
Isotactic poly(1-butene) (i-PBu) is a polyolefin of industrial relevance which exhibits an interesting polymorphism. Upon cooling from the relaxed melt at atmospheric pressure, a tetragonal phase (Form II) develops. However, being metastable, this structure slowly evolves upon aging in the stable trigonal modification (Form I). Another trigonal modification, denoted Form I′, can also crystallize directly from the melt if proper conditions are met, e.g., high pressure, low tacticity, ultrathin samples etc. In this work, we aim to verify whether, by acting on the nucleation stage via a proper thermal history, the direct formation of the trigonal polymorph from the melt in a bulk sample is possible. Nucleation of i-PBu has been tailored by means of the self-nucleation technique, imposed on previously aged samples (Form I). DSC and temperature-resolved WAXS show that different crystallization pathways can be observed, depending on the residual concentration of Form I self-nuclei. With decreasing self-nucleation temperature we first encounter “cross-nucleation” of the tetragonal crystal on trigonal nuclei, followed by concomitant crystallization of Form II and Form I′ and eventually the sole formation of the trigonal modification (Form I′).  相似文献   
156.
Body area networks (BANs) are emerging as enabling technology for many human-centered application domains such as health-care, sport, fitness, wellness, ergonomics, emergency, safety, security, and sociality. A BAN, which basically consists of wireless wearable sensor nodes usually coordinated by a static or mobile device, is mainly exploited to monitor single assisted livings. Data generated by a BAN can be processed in real-time by the BAN coordinator and/or transmitted to a server-side for online/offline processing and long-term storing. A network of BANs worn by a community of people produces large amount of contextual data that require a scalable and efficient approach for elaboration and storage. Cloud computing can provide a flexible storage and processing infrastructure to perform both online and offline analysis of body sensor data streams. In this paper, we motivate the introduction of Cloud-assisted BANs along with the main challenges that need to be addressed for their development and management. The current state-of-the-art is overviewed and framed according to the main requirements for effective Cloud-assisted BAN architectures. Finally, relevant open research issues in terms of efficiency, scalability, security, interoperability, prototyping, dynamic deployment and management, are discussed.  相似文献   
157.
158.
A rapid simple and economical method was described for the determination of ochratoxin A produced by Aspergillusochraceus ITEM 5117 grown in a biofermenter in submerged culture. The ochratoxin A was determinate with RP-HPLC-FLD (reverse phase high performance liquid chromatography) with direct injection in the HPLC apparatus using a C18 column. The mycotoxin was completely resolved by using the mixture acetonitrile, water and acetic acid (49:49:2 v/v) as the mobile phase with a flow rate of 1.0 mL/min. Mean recoveries of ochratoxin A ranged from 95.36% to 103.15%. The limit of detection for ochratoxin A in medium was found to be 1 μg L−1.  相似文献   
159.
Population models are widely applied in biomedical data analysis since they characterize both the average and individual responses of a population of subjects. In the absence of a reliable mechanistic model, one can resort to the Bayesian nonparametric approach that models the individual curves as Gaussian processes. This paper develops an efficient computational scheme for estimating the average and individual curves from large data sets collected in standardized experiments, i.e. with a fixed sampling schedule. It is shown that the overall scheme exhibits a “client-server” architecture. The server is in charge of handling and processing the collective data base of past experiments. The clients ask the server for the information needed to reconstruct the individual curve in a single new experiment. This architecture allows the clients to take advantage of the overall data set without violating possible privacy and confidentiality constraints and with negligible computational effort.  相似文献   
160.
This research has two main purposes. The first is to replicate and possibly to extend the results obtained in a previous study, where the authors found that visitors to the ancient art museum conducted their visit with the primary aim of acquiring understanding and knowledge, while modern art museum visitors conducted their visit with an approach that was primarily emotional and pleasure-seeking. The second purpose relates to studies showing that people who prefer abstract art present higher levels on personality traits like “Openness to Experience” and “Sensation Seeking,” compared to people who prefer realistic art. This study investigates these two personality traits for people who favor visiting museums of ancient rather than modern art. Results confirmed previous findings that emotional aspects related to the visit were relevant for modern art museum visitors, while a more cognitive approach based on learning characterized ancient art museum visitors. Concerning personality traits, no difference was found between the two museum groups on the “Openness to Experience” dimension; differences were found on the “Sensation Seeking” trait; modern art museum visitors attained higher scores as compared to ancient art museum visitors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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