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   3256篇
  免费   206篇
  国内免费   24篇
电工技术   50篇
综合类   15篇
化学工业   722篇
金属工艺   84篇
机械仪表   159篇
建筑科学   137篇
矿业工程   4篇
能源动力   169篇
轻工业   272篇
水利工程   33篇
石油天然气   21篇
武器工业   3篇
无线电   456篇
一般工业技术   541篇
冶金工业   197篇
原子能技术   22篇
自动化技术   601篇
  2023年   45篇
  2022年   92篇
  2021年   160篇
  2020年   162篇
  2019年   171篇
  2018年   229篇
  2017年   181篇
  2016年   189篇
  2015年   117篇
  2014年   197篇
  2013年   349篇
  2012年   197篇
  2011年   235篇
  2010年   170篇
  2009年   153篇
  2008年   117篇
  2007年   79篇
  2006年   68篇
  2005年   53篇
  2004年   35篇
  2003年   28篇
  2002年   13篇
  2001年   24篇
  2000年   14篇
  1999年   15篇
  1998年   47篇
  1997年   37篇
  1996年   32篇
  1995年   28篇
  1994年   24篇
  1993年   21篇
  1992年   18篇
  1991年   24篇
  1990年   18篇
  1989年   9篇
  1988年   11篇
  1987年   15篇
  1986年   14篇
  1985年   10篇
  1984年   6篇
  1983年   5篇
  1982年   6篇
  1981年   7篇
  1980年   5篇
  1977年   5篇
  1976年   10篇
  1975年   4篇
  1973年   6篇
  1970年   8篇
  1969年   4篇
排序方式: 共有3486条查询结果,搜索用时 22 毫秒
1.
Food- and waterborne viruses, such as human norovirus, hepatitis A virus, hepatitis E virus, rotaviruses, astroviruses, adenoviruses, and enteroviruses, are major contributors to all foodborne illnesses. Their small size, structure, and ability to clump and attach to inanimate surfaces make viruses challenging to reduce or eliminate, especially in the presence of inorganic or organic soils. Besides traditional wet and dry methods of disinfection using chemicals and heat, emerging physical nonthermal decontamination techniques (irradiation, ultraviolet, pulsed light, high hydrostatic pressure, cold atmospheric plasma, and pulsed electric field), novel virucidal surfaces, and bioactive compounds are examined for their potential to inactivate viruses on the surfaces of foods or food contact surfaces (tools, equipment, hands, etc.). Every disinfection technique is discussed based on its efficiency against viruses, specific advantages and disadvantages, and limitations. Structure, genomic organization, and molecular biology of different virus strains are reviewed, as they are key in determining these techniques effectiveness in controlling all or specific foodborne viruses. Selecting suitable viral decontamination techniques requires that their antiviral mechanism of action and ability to reduce virus infectivity must be taken into consideration. Furthermore, details about critical treatments parameters essential to control foodborne viruses in a food production environment are discussed, as they are also determinative in defining best disinfection and hygiene practices preventing viral infection after consuming a food product.  相似文献   
2.
3.
4.
Neural Processing Letters - Facial expression is an important aspect to recognize emotions between humans. However, this task remains difficult for machines. Several approaches have been developed...  相似文献   
5.
In this work, we will study the crystallization of P type hydrogenated amorphous silicon (a-Si:H) by Aluminum Induced Crystallization technique (CIA) by varying the thickness of the aluminum films. We have deposited a 100 nm thickness of p-type a-Si:H layer on Corning glass substrates using PECVD technique. An aluminum layer with thickness ranging from 10 to 400 nm was thermally evaporated on the a-Si:H surface. The thermal annealing was performed in a conventional furnace at temperature of 550 °C for 4 h in flowing N2 ambient. The study of the crystallization of the Al/a-Si:H/Glass structure according the aluminum thickness was carried out by using Raman spectroscopy, X-rays diffraction and Hall Effect measurements. Raman results reveal the presence of the peaks between 510 and 520 cm−1, which are close to the peak of crystallized Si (about 521 cm−1) proving the crystallization of all samples. The XRD measurements show the presence of the characteristic peaks of the crystalline silicon, thus the a-Si: H (p) layer was effectively crystallized by the AIC method in a short time. Through Hall measurements we found an improvement in electrical properties and an increase in dopant concentration (+ 5.3 1014 to + 2.9 1017 cm2).  相似文献   
6.
Multimedia Tools and Applications - In e-healthcare applications integrity of the received information is of prime importance for ensuring the accurate diagnosis. The integrity of electronic...  相似文献   
7.
Protection of Metals and Physical Chemistry of Surfaces - Single NbSi2 and duplex NbSi2/Nb5Si3 coatings were successfully applied on Nb substrates using halide activated pack cementation (HAPC)...  相似文献   
8.
The purpose of this study was to investigate the effect of carbon fiber (CF) and electron‐beam (EB) radiation on high‐temperature mechanical properties of ethylene‐vinyl acetate (EVA). Polymer composites were prepared by mixing on a two‐roll mill. After compression molding, the samples were irradiated between 60 and 180 kGy, and dynamic mechanical analysis (DMA) was used to characterize physical properties. The effects of filler content and radiation level on the mechanical properties of EVA/CF were evaluated. The shear stress and modulus were observed to increase with increasing of the filler level. However, there was a dramatic decrease in creep compliance. It was also shown that introduction of irradiation on EVA composite increases the shear stress and the real part of the dynamic shear modulus G' due to the increase in molecular weight and cross‐linking of the polymer after irradiation. J. VINYL ADDIT. TECHNOL., 26:325–335, 2020. © 2019 Society of Plastics Engineers  相似文献   
9.
Quasi-static and dynamic three-point-bending experiments were conducted on both annealed and chemically strengthened aluminosilicate glass scratched by different normal loads. Scratched areas were observed by optical microscope and atomic force microscope. Chemically strengthened glass shows better resistance to surface scratch. These dynamic experiments were carried out using a modified Split Hopkinson Pressure Bar (SHPB) device and a pulse-shaping technique was used to keep constant loading speed to the specimens. In tests, high-speed photography was also used to observe the failure process of the specimens. The test results showed that the flexural strength of aluminosilicate glass (AG) strongly depends on the applied loading speed. Compared with its annealed counterpart, the chemically strengthened glass (CSG) showed higher flexural strength to both static and dynamic loadings. Moreover, the three-point bending experiments were conducted on scratched AG and CSG specimens and decrease of 20–40% in flexural strength was observed. The fractography analysis showed that in dynamic loading conditions the fracture surface was not smooth and has more secondary cracks as compared to static loading.  相似文献   
10.
Conductometric and cloud point (CP) measurement studies have been performed to investigate the interaction of tetradecyltrimethylammonium bromide (TTAB) and Triton® X-100 (TX-100) with ciprofloxacin hydrochloride (CFH) in different solvents over the temperature range of 295.15–315.15 K. CFH is used for the treatment of various bacterial infections. The observed critical micelle concentration (CMC) values of TTAB were found to be reduced in the presence of electrolytes (Na2SO4/Na3PO4), and this reduction proceeds with the elevation of salt concentration. The order of the CMC of TTAB follows the trend: > >. The observed CMC values of TTAB were found to increase with increasing temperature and decrease with increasing concentration of CFH in aqueous medium. The values of Gibbs free energy of micellization () for the TTAB/TTAB + CFH mixture were found to be negative, implying spontaneous micellization. The estimated CP of TX-100 decreases with increasing concentration of TX-100 in aqueous medium. The CP values first decrease with increasing concentration of CFH and then increase at higher concentration of CFH almost in all cases investigated. The values of free energy of clouding were found to be positive in all cases studied implying that phase separation of TX-100 was nonspontaneous. The other thermodynamic parameters associated with the micellization of TTAB and the phase separation of TX-100 were estimated and explained.  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