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   353篇
  免费   34篇
  国内免费   6篇
电工技术   2篇
综合类   1篇
化学工业   123篇
金属工艺   2篇
机械仪表   15篇
建筑科学   13篇
能源动力   12篇
轻工业   47篇
石油天然气   2篇
无线电   37篇
一般工业技术   69篇
冶金工业   15篇
自动化技术   55篇
  2024年   3篇
  2023年   8篇
  2022年   41篇
  2021年   42篇
  2020年   27篇
  2019年   20篇
  2018年   23篇
  2017年   21篇
  2016年   27篇
  2015年   15篇
  2014年   11篇
  2013年   30篇
  2012年   8篇
  2011年   18篇
  2010年   21篇
  2009年   12篇
  2008年   15篇
  2007年   8篇
  2006年   9篇
  2005年   7篇
  2004年   2篇
  2003年   4篇
  2002年   4篇
  2000年   2篇
  1998年   3篇
  1997年   2篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1990年   1篇
  1988年   1篇
  1985年   1篇
  1975年   1篇
排序方式: 共有393条查询结果,搜索用时 31 毫秒
81.
Smoking is a risk factor for a variety of deleterious conditions, such as cancer, respiratory disease and cardiovascular disease. Thrombosis is an important and common aspect of several cardiovascular disease states, whose risk is known to be increased by both first- and secondhand smoke. More recently, the residual cigarette smoke that persists after someone has smoked (referred to as thirdhand smoke or THS) has been gaining more attention, since it has been shown that it also negatively affects health. Indeed, we have previously shown that 6-month exposure to THS increases the risk of thrombogenesis. However, neither the time-dependence of THS-induced thrombus formation, nor its sex dependence have been investigated. Thus, in the present study, we investigated these issues in the context of a shorter exposure to THS, specifically 3 months, in male and female mice. We show that the platelets from 3-month THS-exposed mice exhibited enhanced activation by agonists. Moreover, we also show that mice of both sexes exposed to THS have decreased tail bleeding as well as decreased thrombus occlusion time. In terms of the role of sex, intersex disparities in thrombus development and hemostasis as well as in platelet aggregation were, interestingly, observed. Together, our findings show that exposing mice to THS for 3 months is sufficient to predispose them to thrombosis; which seems to be driven, at least in part, by an increased activity in platelets, and that it does not manifest equally in both sexes.  相似文献   
82.

Depth image based rendering (DIBR) is a popular technique for rendering virtual 3D views in stereoscopic and autostereoscopic displays. The quality of DIBR-synthesized images may decrease due to various factors, e.g., imprecise depth maps, poor rendering techniques, inaccurate camera parameters. The quality of synthesized images is important as it directly affects the overall user experience. Therefore, the need arises for designing algorithms to estimate the quality of the DIBR-synthesized images. The existing 2D image quality assessment metrics are found to be insufficient for 3D view quality estimation because the 3D views not only contain color information but also make use of disparity to achieve the real depth sensation. In this paper, we present a new algorithm for evaluating the quality of DIBR generated images in the absence of the original references. The human visual system is sensitive to structural information; any deg radation in structure or edges affects the visual quality of the image and is easily noticeable for humans. In the proposed metric, we estimate the quality of the synthesized view by capturing the structural and textural distortion in the warped view. The structural and textural information from the input and the synthesized images is estimated and used to calculate the image quality. The performance of the proposed quality metric is evaluated on the IRCCyN IVC DIBR images dataset. Experimental evaluations show that the proposed metric outperforms the existing 2D and 3D image quality metrics by achieving a high correlation with the subjective ratings.

  相似文献   
83.
Journal of Mechanical Science and Technology - The resolution of Harten’s non-oscillatory explicit second-order accurate total variation diminishing scheme was relatively high for...  相似文献   
84.
Polypyrrole one-dimensional nanostructures (nanotubes, nanobelts and nanofibers) were prepared using three various dyes (Methyl Orange, Methylene Blue and Eriochrome Black T). Their high electrical conductivity (from 17.1 to 60.9 S cm−1), good thermal stability (in the range from 25 to 150 °C) and resistivity against ageing (half-time of electrical conductivity around 80 days and better) were used in preparation of lightweight and flexible composites with silicone for electromagnetic interference shielding in the C-band region (5.85–8.2 GHz). The nanostructures’ morphology and chemical structure were characterized by scanning electron microscopy, Brunauer–Emmett–Teller specific surface measurement and attenuated total reflection Fourier-transform infrared spectroscopy. DC electrical conductivity was measured using the Van der Pauw method. Complex permittivity and AC electrical conductivity of respective silicone composites were calculated from the measured scattering parameters. The relationships between structure, electrical properties and shielding efficiency were studied. It was found that 2 mm-thick silicone composites of polypyrrole nanotubes and nanobelts shield almost 80% of incident radiation in the C-band at very low loading of conductive filler in the silicone (5% w/w). Resulting lightweight and flexible polypyrrole composites exhibit promising properties for shielding of electromagnetic interference in sensitive biological and electronic systems.  相似文献   
85.
Multidrug resistance (MDR) is one of the major factors in the failure of many chemotherapy approaches. In cancer cells, MDR is mainly associated with the expression of ABC transporters such as P-glycoprotein, MRP1 and ABCG2. Despite major efforts to develop new selective and potent inhibitors of ABC drug transporters, no ABCG2-specific inhibitors for clinical use are yet available. Here, we report the evaluation of sixteen tetrahydroquinoline/4,5-dihydroisoxazole derivatives as a new class of ABCG2 inhibitors. The affinity of the five best inhibitors was further investigated by the vanadate-sensitive ATPase assay. Molecular modelling data, proposing a potential binding mode, suggest that they can inhibit the ABCG2 activity by binding on site S1, previously reported as inhibitors binding region, as well targeting site S2, a selective region for substrates, and by specifically interacting with residues Asn436, Gln398, and Leu555. Altogether, this study provided new insights into THQ/4,5-dihydroisoxazole molecular hybrids, generating great potential for the development of novel most potent ABCG2 inhibitors.  相似文献   
86.
Recently, photocatalysis has received huge attention in order to overcome energy crisis worldwide. Many semiconductors, potential schemes and hierarchies have come to light during past few decades to fabricate efficient catalysts however, among all these methods heterostructures have taken the world by surprise. With the advancement in post-graphene 2D materials, van der Waals heterostructures have come to light exploring enhancement in photocatalysis. During a very short period a number of ZnO-based van der Waal heterostructures have taken the limelight in the field of photocatalysis. First principles calculations and DFT approach towards the heterostructures of GeC, GaN, WSe2, WS2 and other layered 2D materials unleased a series of properties and facts for the provision of enhanced catalysis. Reduction in bandgap of ZnO has also been observed which widens the pathways towards visible light irradiation. However, energy applications of zinc oxide are also fascinating feature as it can serve as a photoanode to replace TiO2. Whereas the famous hydrogen production, batteries and solar cells have also been fabricated by the use of this semiconductor.  相似文献   
87.
This systematic literature review paper investigates the key techniques employed to identify smells in different paradigms of software engineering from object-oriented (OO) to service-oriented (SO). In this review, we want to identify commonalities and differences in the identification of smells in OO and SO systems. Our research method relies on an automatic search from the relevant digital libraries to find the studies published since January 2000 on smells until December 2017. We have conducted a pilot and author-based search that allows us to select the 78 most relevant studies after applying inclusion and exclusion criteria. We evaluated the studies based on the smell detection techniques and the evolution of different methodologies in OO and SO. Among the 78 relevant studies selected, we have identified six different studies in which linguistic source code analysis received less attention from the researchers as compared to the static source code analysis. Smells like the yo-yo problem, unnamed coupling, intensive coupling, and interface bloat received considerably less attention in the literature. We also identified a catalog of 30 smells infrequently reported for SO systems and that require further attention. Moreover, a suite of 20 smells reported for SO systems can also be detected using static source code metrics in OO. Finally, our review highlighted three major research trends that are further subdivided into 20 research patterns initiating the detection of smells toward their correction.  相似文献   
88.
Chia oil has a high content of linolenic and linoleic acids, which are essential for the human body. However, their high degree of unsaturation (double bonds) makes the oil very susceptible to oxidation. In this context, the use of spray drying can be useful strategy to minimize the oxidation of this oil. Thus, the aim was to assess the effects of inlet temperature and feed rate conditions involved in the spray drying process on the physicochemical and morphological characteristics, and stability of the chia oil microparticles with maltodextrin and GA. The microparticles were obtained with a yield of 50%, encapsulation efficiency greater than 87%, low-moisture content, and mean particle sizes ranging from 3.01 to 4.11 μm. The thermal evaluation and storage evidenced an increase in stability. The 1H HR-MAS NMR technique showed that the microparticles maintained the characteristic fatty acid profile of chia oil and seeds. Results indicate that the microencapsulation methodology was suitable for preparing microparticles containing chia oil.  相似文献   
89.
The current study investigates the comparison and quality characteristics of starches isolated from potatoes using different processing methods from three commercial varieties: Lady Rosetta, Asterix and Challenger, for the first time in Pakistan. The analysis of variance revealed that starch yield significantly (P < 0.05) depended on total solids, peeling (12.7%, 12.0% and 12.0%) and unpeeling (15.0%, 14.0% and 14.0%) of potatoes compared to potato varieties for Lady Rosetta, Challenger and Asterix, respectively. Moreover, pasting properties, protein content, redness and yellowness were increased in those starches isolated without peeling while carbohydrates and lightness were increased in peeled potato starches. Furthermore, Fourier-transform infrared spectroscopy analysis revealed that protein (1200–1400 cm−1) was present in starch extracted without peeling. Besides, scanning electron microscopy analysis revealed oval-shaped starch granules with no impurities in peeled potato starch. The findings suggest the suitability of peeling process for obtaining a high-quality pure starch.  相似文献   
90.
Wireless Personal Communications - The complexity of network technologies and the variety of their equipment and settings make them difficult to evaluate, to simulate, and to deploy. IPv4 to IPv6...  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