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   1682225篇
  免费   34617篇
  国内免费   10415篇
电工技术   39022篇
技术理论   11篇
综合类   11533篇
化学工业   283691篇
金属工艺   70041篇
机械仪表   50949篇
建筑科学   54613篇
矿业工程   13943篇
能源动力   52775篇
轻工业   129594篇
水利工程   17680篇
石油天然气   42490篇
武器工业   790篇
无线电   208421篇
一般工业技术   310106篇
冶金工业   222019篇
原子能技术   35390篇
自动化技术   184189篇
  2021年   18530篇
  2020年   14400篇
  2019年   16765篇
  2018年   20576篇
  2017年   20321篇
  2016年   25106篇
  2015年   20920篇
  2014年   32811篇
  2013年   93110篇
  2012年   43544篇
  2011年   58350篇
  2010年   49984篇
  2009年   57335篇
  2008年   53148篇
  2007年   50729篇
  2006年   51248篇
  2005年   46193篇
  2004年   46333篇
  2003年   45729篇
  2002年   44439篇
  2001年   41464篇
  2000年   39434篇
  1999年   39687篇
  1998年   63637篇
  1997年   51189篇
  1996年   43538篇
  1995年   35789篇
  1994年   32931篇
  1993年   32595篇
  1992年   27720篇
  1991年   24863篇
  1990年   24636篇
  1989年   23531篇
  1988年   22077篇
  1987年   20150篇
  1986年   19568篇
  1985年   22859篇
  1984年   22540篇
  1983年   20482篇
  1982年   19428篇
  1981年   19591篇
  1980年   18257篇
  1979年   18579篇
  1978年   17912篇
  1977年   18588篇
  1976年   21097篇
  1975年   16075篇
  1974年   15487篇
  1973年   15636篇
  1972年   13178篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
991.
Consumer studies and market reports show an increase in consumption of ready‐to‐eat (RTE) foods. Although conventional processing technologies can in most cases produce safe products, they can also lead to the degradation of nutritional compounds and negatively affect quality characteristics. Consumers strongly prefer food that is minimally processed with the maximum amount of health‐promoting substances. Novel processing technologies as pre‐ or post‐treatment decontamination methods or as substitutes of conventional technologies have the potential to produce foods that are safe, rich in nutrient content and with superior organoleptic properties. Combining novel with conventional processes can eliminate potential drawbacks of novel technologies. This review examines available scientific information and critically evaluates the suitability and efficiency of various novel thermal and nonthermal technologies in terms of microbial safety, quality as well as nutrient content on the production of RTE meals, meats and pumpable products.  相似文献   
992.
CAR (Chimeric Antigen Receptor) T cells have demonstrated clinical success for the treatment of multiple lymphomas and leukaemias, but not for various solid tumours, despite promising data from murine models. Lower effective CAR T-cell delivery rates to human solid tumours compared to haematological malignancies in humans and solid tumours in mice might partially explain these divergent outcomes. We used anatomical and physiological data for human and rodent circulatory systems to calculate the typical perfusion of healthy and tumour tissues, and estimated the upper limits of immune cell delivery rates across different organs, tumour types and species. Estimated maximum delivery rates were up to 10 000-fold greater in mice than humans yet reported CAR T-cell doses are typically only 10–100-fold lower in mice, suggesting that the effective delivery rates of CAR T cells into tumours in clinical trials are far lower than in corresponding mouse models. Estimated delivery rates were found to be consistent with published positron emission tomography data. Results suggest that higher effective human doses may be needed to drive efficacy comparable to mouse solid tumour models, and that lower doses should be tested in mice. We posit that quantitation of species and organ-specific delivery and homing of engineered T cells will be key to unlocking their potential for solid tumours.  相似文献   
993.
Pokutnyi  S. I.  Dzyuba  V. P.  Amosov  A. V. 《Semiconductors》2019,53(16):2045-2048
Semiconductors - The optical properties of dielectric nanostructures strongly depend on dielectric nanoparticles (NP) polarizability which can take the high values even interacting with...  相似文献   
994.
International Journal of Mechanics and Materials in Design - The resonant frequency of electromechanical energy harvester should be tuned to ambient frequency so as to maximize the harvester power....  相似文献   
995.
Sanad  M. H.  Marzook  F.  Saleh  G. M.  Farag  A. B.  Talaat  H. M. 《Radiochemistry》2019,61(4):478-482
Radiochemistry - Azathioprine, an antitumor agent, was labeled with 99mTc using stannous chloride dihydrate as a reducing agent. Factors such as the amounts of the reducing agent and substrate, pH,...  相似文献   
996.
Nochovnaya  N. A.  Shiryaev  A. A. 《Metallurgist》2019,63(7-8):742-750
Metallurgist - A forming operations for the pseudo-α titanium alloys OT4-1, OT4-1V, OT4V that are used traditionally in aviation and aerospace transport structures, and a new advanced...  相似文献   
997.
Azab  A. A.  Esmail  S. A.  Abdelamksoud  M. K. 《SILICON》2019,11(1):165-174
Silicon - Nano-crystalline powders of Zn1−xCoxO with $\left (0.0\le x\le 0.07 \right )$ have been synthesized by sol-gel method. X-ray diffraction patterns of the prepared samples confirm the...  相似文献   
998.
999.
1000.
In this work, p-NiO/n-ZnO heterostructures were successfully prepared at room temperature using RF sputtering technique. The influence of ZnO layer thickness on the performance of the heterojunction was investigated. The deposited ZnO layers have a hexagonal Wurtzite structure with preferable growth orientations along (002) and (103) for thinner films. Increasing the thickness results in more crystallographic orientation randomness. The current–voltage measurements of the realized heterojunctions showed a clear rectifying behavior. The measured ideality factor varies from 2.5 to 1.6 according to the thickness of ZnO layer. The series resistance of the device is enlarged with increasing ZnO thickness. The deduced parameters from the I–V characteristics suggest that 200 nm is the optimal thickness of the ZnO layer according to our experimental conditions. We attribute the relatively better performance of this thickness to achieving reasonable compensation between serial resistance and ideality factor. The best heterojunction was tested and successfully used as a UV detector.  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