首页 | 官方网站   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   4674篇
  免费   323篇
  国内免费   10篇
工业技术   5007篇
  2024年   10篇
  2023年   54篇
  2022年   85篇
  2021年   227篇
  2020年   157篇
  2019年   174篇
  2018年   173篇
  2017年   198篇
  2016年   203篇
  2015年   167篇
  2014年   231篇
  2013年   412篇
  2012年   353篇
  2011年   395篇
  2010年   308篇
  2009年   263篇
  2008年   257篇
  2007年   208篇
  2006年   165篇
  2005年   134篇
  2004年   113篇
  2003年   99篇
  2002年   102篇
  2001年   58篇
  2000年   50篇
  1999年   52篇
  1998年   66篇
  1997年   44篇
  1996年   50篇
  1995年   24篇
  1994年   18篇
  1993年   23篇
  1992年   9篇
  1991年   11篇
  1990年   14篇
  1989年   11篇
  1988年   9篇
  1987年   3篇
  1986年   6篇
  1985年   10篇
  1984年   9篇
  1983年   8篇
  1982年   3篇
  1981年   8篇
  1980年   4篇
  1978年   4篇
  1977年   6篇
  1976年   4篇
  1974年   3篇
  1973年   5篇
排序方式: 共有5007条查询结果,搜索用时 109 毫秒
991.
Pinto  José Pedro  Pimenta  André  Novais  Paulo 《Machine Learning》2021,110(11-12):3037-3057
Machine Learning - Online video games drive a multi-billion dollar industry dedicated to maintaining a competitive and enjoyable experience for players. Traditional cheat detection systems struggle...  相似文献   
992.
993.
Biogenic amines (BAs) are compounds present in foodstuff of animal origin that not only can be harmful to the consumer but can also serve as indicators of the product's edibility status. However, BAs’ analysis is rather complicated. Derivatisation methods have been employed to make their analysis less challenging. Salting-out assisted liquid–liquid extraction (SALLE) was herein applied to decrease time that the derivatising agent dansyl chloride (DNS-Cl) requires to be effective. DNS-Cl derivates were separated and analysed by high-performance liquid chromatography with UV and fluorescence detection (HPLC-UV/FD). It was by this way possible to analyse methylamine, dimethylamine, ethylamine, β-phenylethylamine, isopentylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine in a straightforward manner in several fish-based and meat-based samples, obtaining results in the order of magnitude of about a few mg per kg. All calibrations curves had r2 higher than 0.99, and limits of detection ranged from 0.0075 to 1.6 mg L−1.  相似文献   
994.
Magnetic beads composed by polyvinyl alcohol and iron oxides were developed and fully characterized. The materials were not only cross-linked by a physical treatment but also the magnetic nanoparticles (MNPs) are acting as cross-linking dots. Interestingly, the analysis of scanning electron micrographs revealed that, in the case of hydrated samples, flower-like structures (average diameter 6–9 μm) being constituted by MNPs were present, whereas when the beads were dried the MNPs structure changed to porous spheres (average diameter 2–3 μm). Some of the prepared materials were tested to determine their capability to act as water remediation devices, and good removal results were obtained toward both methylene blue (average removal efficiency higher than 80%) and methyl orange (average removal efficiency lower than 30%) adsorption. The experiments performed confirmed that the adsorbent, once the treatment has ended, can be removed off through the simple employment of a permanent magnet.  相似文献   
995.
In this work, rotational molding was used to produce parts based on a blend of linear low-density polyethylene (LLDPE) and polyamide 6 (PA6). In particular, the concentration of PA6 (0, 10, 20, and 30% vol) with and without a compatibilizer (Surlyn 9020) was investigated via two methods: dry blending in a high-shear mixer and melt compounding in a twin-screw extruder followed by pulverization. To determine the efficiency of the rotomolding process, similar parts were produced via compression molding. For rotational molding, dry ice (solid CO2) was used to create an inert atmosphere in the mold and the processing conditions were followed by the mold internal air temperature traces. From the samples produced, thermal, morphological, and mechanical properties were measured. The results showed that the rotomolded parts of the melt blended compounds generated smaller and better dispersed PA6 particles in the LLDPE matrix. This finer morphology led to improved mechanical properties, especially when the compatibilizer was present. But the latter was found to be more effective on the compression-molded samples.  相似文献   
996.
Multimedia Tools and Applications - Due to the increasing shortage of fish in the seas, Vessel Monitoring Systems (VMS) play a very important role in fishing activity monitoring, control and...  相似文献   
997.
In this work, metal-ceramic composite parts based on aluminum and alumina were manufactured in a two-stage process. First, silica was printed using a vat photopolymerization technique, followed by a curing and sintering stage, which resulted in ceramic precursors. Subsequently, these samples were subjected to a metal infiltration process to form interpenetrating metal-ceramic composites (IPCs). These composites have attracted considerable attention in the aerospace and defense sector due to the ductility associated to the metal phase and the strength offered by the ceramics. A novel application with utility includes composite tooling which requires a low coefficient of thermal expansion (CTE) for high temperatures. The investigated specimens were tested for surface quality and shrinkage, followed by a mechanical characterization. It was recorded that the samples presented a 12%–18% of shrinkage after the sintering process. The mechanical testing showed that the hardness, compression, and flexural strength of the composites were superior to the printed and sintered ceramics. A thermal analysis on the composite showed that its CTE is more than two times lower than the common composite tooling materials. It is expected that the present work can provide the foundations for further studies on these systems in the refractory, automotive, and armor-based fields.  相似文献   
998.
In fish, fasting leads to loss of muscle mass. This condition triggers oxidative stress, and therefore, antioxidants can be an alternative to muscle recovery. We investigated the effects of antioxidant ascorbic acid (AA) on the morphology, antioxidant enzyme activity, and gene expression in the skeletal muscle of pacu (Piaractus mesopotamicus) following fasting, using in vitro and in vivo strategies. Isolated muscle cells of the pacu were subjected to 72 h of nutrient restriction, followed by 24 h of incubation with nutrients or nutrients and AA (200 µM). Fish were fasted for 15 days, followed by 6 h and 15 and 30 days of refeeding with 100, 200, and 400 mg/kg of AA supplementation. AA addition increased cell diameter and the expression of anabolic and cell proliferation genes in vitro. In vivo, 400 mg/kg of AA increased anabolic and proliferative genes expression at 6 h of refeeding, the fiber diameter and the expression of genes related to cell proliferation at 15 days, and the expression of catabolic and oxidative metabolism genes at 30 days. Catalase activity remained low in the higher supplementation group. In conclusion, AA directly affected the isolated muscle cells, and the higher AA supplementation positively influenced muscle growth after fasting.  相似文献   
999.
To design the X¯ control chart, the in-control process mean and standard deviation must be estimated from historical samples, negatively affecting the chart's performance. The grand mean of a sample is the well-established estimator for the process mean. However, regarding the standard deviation, the chart's user has at least five different estimators available in the literature to choose from. In this paper, using intensive simulations, we study and compare the performance of the X¯ chart (under normality assumption and three-sigma limits) among the most five used standard deviation estimators. The unconditional in-control run length (RL0) is the most commonly used performance measure of a control chart, and many authors base their comparisons on the expectation of the RL0 or on the mean square error of the estimators. In contrast, we based our comparison on the proportions of the RL0 concentrated at some intervals that are usually considered undesired by the practitioner due to the high incidence of false alarms during the process monitoring (e.g., RL0 between 1 and 200), occurring earlier than expected when compared with known parameter situations. From our results, all the studied standard deviation estimators generate similar performances. However, even with this similarity, we showed that one of the most recommended standard deviation estimators in the literature in control charts with estimated parameters may be the most inappropriate choice based on the undesired RL0 proportions.  相似文献   
1000.
At a time when communication, new media, and digitalization are transversal to the whole of society, private health care organizations have the possibility of making their business processes evolve. The objective is thus to seize the benefits associated to the active use of patients' electronic health records (EHRs) as the basis for personalized health care. In order to initially validate the health care sector acceptance of a 360° health care information system (HIS), focused on collecting patients' data to create the necessary knowledge for delivering personalized health care procedures and initiatives, a focus group involving a set of health-related professionals was performed. Despite recognizing the immense possibilities associated to EHR and its direct incorporation on a 360° HIS, the referred professionals still highlighted their concerns relative to the maintenance of adequate security and privacy levels. With this in mind, a proposal for a 360° HIS model is presented, and its main functional blocks are described with a focus on triggering patient/customer loyalty.  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-23

京公网安备 11010802026262号