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   492924篇
  免费   11634篇
  国内免费   4356篇
电工技术   12039篇
技术理论   9篇
综合类   4934篇
化学工业   76386篇
金属工艺   20480篇
机械仪表   17203篇
建筑科学   17029篇
矿业工程   3646篇
能源动力   13782篇
轻工业   40034篇
水利工程   5188篇
石油天然气   10555篇
武器工业   505篇
无线电   61015篇
一般工业技术   90067篇
冶金工业   82952篇
原子能技术   9498篇
自动化技术   43592篇
  2022年   4395篇
  2021年   6390篇
  2020年   4701篇
  2019年   5043篇
  2018年   7359篇
  2017年   7643篇
  2016年   7668篇
  2015年   6551篇
  2014年   10340篇
  2013年   23470篇
  2012年   15363篇
  2011年   19622篇
  2010年   16200篇
  2009年   17739篇
  2008年   17893篇
  2007年   17659篇
  2006年   16297篇
  2005年   14617篇
  2004年   12900篇
  2003年   12611篇
  2002年   11738篇
  2001年   12011篇
  2000年   11532篇
  1999年   12436篇
  1998年   27935篇
  1997年   19739篇
  1996年   15480篇
  1995年   11782篇
  1994年   10275篇
  1993年   9871篇
  1992年   7052篇
  1991年   6693篇
  1990年   6358篇
  1989年   6128篇
  1988年   5911篇
  1987年   5028篇
  1986年   4918篇
  1985年   5408篇
  1984年   4978篇
  1983年   4655篇
  1982年   4344篇
  1981年   4336篇
  1980年   4087篇
  1979年   3932篇
  1978年   3709篇
  1977年   4527篇
  1976年   6024篇
  1975年   3174篇
  1974年   3126篇
  1973年   3135篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast...  相似文献   
4.
The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results.  相似文献   
5.
The effect of microwave roasting parameters (300, 450 and 600 W; 5, 10 and 15 min) on acrylamide content in sorghum grain was determined using High Pressure Liquid Chromatography (HPLC)-photo diode array (PDA) detector coupled with C-18 column. Samples roasted at 300 and 450 W did not possess acrylamide, whereas 600 W (15 min) favoured formation of 2740.19 µg/kg of acrylamide, levels far exceeding the defined European Union (EU) limits. The chronic daily intake (CDI) for acrylamide through consumption of such grain flour was 3.25–9.5-fold higher to Joint FAO/WHO Expert Committee on Food Additives (JECFA) defined high exposure limits. The margin of exposure (MOE) values ranged from 4.3 to 12.76 and from 11.07 to 32.27 for neoplastic and neurological effects, respectively, demonstrating high exposure and serious health concerns associated with dietary intake of this toxicant. This study assesses the risk for the Indian population and highlights the importance of optimising process parameters for food product to minimise such exposure risks.  相似文献   
6.
The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non-covalent bonds, the diffusion and cross-linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs-MP group than in the CMFs-MP group. The CNFs-MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP.  相似文献   
7.
针对传统的电弧电路故障检测结果不准确的问题,设计用于电弧检测的SoC系统,并且在55nm工艺下进行流片验证。采用包含两种结构的模数转换器的片上电压源,设计了锁相环以及复位电路,精度最高可达8.67 bit。验证结果表明,本设计可提高电弧检测的准确性。  相似文献   
8.
Fan  Deng-Ping  Huang  Ziling  Zheng  Peng  Liu  Hong  Qin  Xuebin  Van Gool  Luc 《国际自动化与计算杂志》2022,19(4):257-287
Machine Intelligence Research - This paper aims to conduct a comprehensive study on facial-sketch synthesis (FSS). However, due to the high cost of obtaining hand-drawn sketch datasets, there is a...  相似文献   
9.
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell.  相似文献   
10.
Multimedia Tools and Applications - The study presents a new approach to automate segmentation of clinically significant brain tumor and, to a certain extent, addresses two major issues associated...  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