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   92175篇
  免费   6198篇
  国内免费   2541篇
电工技术   3892篇
技术理论   3篇
综合类   3965篇
化学工业   16004篇
金属工艺   4026篇
机械仪表   4544篇
建筑科学   6460篇
矿业工程   1904篇
能源动力   2710篇
轻工业   6516篇
水利工程   1439篇
石油天然气   3957篇
武器工业   528篇
无线电   8586篇
一般工业技术   12840篇
冶金工业   9121篇
原子能技术   845篇
自动化技术   13574篇
  2023年   1186篇
  2022年   1606篇
  2021年   2896篇
  2020年   2349篇
  2019年   2130篇
  2018年   2471篇
  2017年   2558篇
  2016年   2455篇
  2015年   3000篇
  2014年   3960篇
  2013年   5646篇
  2012年   5255篇
  2011年   6116篇
  2010年   5144篇
  2009年   4820篇
  2008年   5006篇
  2007年   4745篇
  2006年   4656篇
  2005年   3996篇
  2004年   3009篇
  2003年   2746篇
  2002年   2646篇
  2001年   2055篇
  2000年   1761篇
  1999年   2034篇
  1998年   1784篇
  1997年   1615篇
  1996年   1476篇
  1995年   1378篇
  1994年   1176篇
  1993年   979篇
  1992年   906篇
  1991年   542篇
  1990年   620篇
  1989年   551篇
  1988年   438篇
  1987年   430篇
  1986年   366篇
  1985年   455篇
  1984年   448篇
  1983年   344篇
  1982年   323篇
  1981年   298篇
  1980年   283篇
  1979年   276篇
  1978年   248篇
  1977年   225篇
  1976年   206篇
  1975年   194篇
  1974年   173篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
Wen  Pushan  He  Rui  Li  Xiang-Dan  Lee  Myong-Hoon 《Journal of Materials Science》2022,57(1):755-765
Journal of Materials Science - Three polyimides (PIs) were prepared from a diamine containing biphenyl ester group as a side chain and a corresponding dianhydride chosen from...  相似文献   
2.
Song  Yupeng  He  Fazhi  Liu  Yanan 《Multimedia Tools and Applications》2022,81(10):13961-13978
Multimedia Tools and Applications - Tree species classification is a necessary and challenging task for both multimedia technique and forestry engineering. Continuous developments in multimedia and...  相似文献   
3.
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   
4.
Lin  Ruijin  He  Yuanrong  Xu  Min 《Wireless Networks》2022,28(6):2733-2741
Wireless Networks - In order to improve the transmission stability of sensor networks, a sensitive data mining method based on Pan Boolean algebra is proposed. According to the output correctness,...  相似文献   
5.
Shu  Fei  Dinneen  Jesse David  Chen  Shiji 《Scientometrics》2022,127(6):3613-3628
Scientometrics - Examining the relationships among scientific disciplines is important today, but existing methods are limited by the contents and structure of their bibliographic databases. We...  相似文献   
6.
Walnut flour (WF), a by-product of walnut oil production, is characterised by high polyunsaturated fatty acids, proteins, and fibre contents and presents suitability for bakery products. However, when using non-traditional ingredients, it is essential to evaluate the effect on the quality properties of the final product. So, this work aimed to assess the impact of WF on the technological, physicochemical, and sensory properties of gluten-free (GF) cakes. WF was added at a flour blend (cassava (CS) and maize (MS) starches and rice flour) at 0, 10%, 15%, and 20%. The results showed that WF modified starch gelatinisation, increased amylose–lipid complex (ALC) content, and made crumbs easier to chew. Besides, the total dietary fibre (TDF) and protein content significantly increased. Cakes with 15% WF presented the highest specific volume (SV) and no differences in overall acceptability with respect to control. Hence, WF is a suitable ingredient for gluten-free bakery products.  相似文献   
7.
This study investigated the effect of 5 freeze–thaw cycles (freezing at −18°C for 12 h and then thawing at 4°C for approximately 12 h) on the meat quality, proximate composition, water distribution and microstructure of bovine rumen smooth muscle (BSM). As the number of freeze–thaw cycles increased, BSM pH, shear force, water content and protein content decreased by 3.06%, 35.50%, 14.49% and 21.11%, respectively, whereas BSM thawing loss, cooking loss, pressing loss, total aerobic count (TAC), ash content and fat content increased by 108.12%, 47.75%, 78.33%, 90.99%, 105% and 35.20%, respectively. The freeze–thaw cycles resulted in greater protein and lipid oxidation, as evidenced by a 36.46% reduction in the sulfhydryl content and a 209.06% and 338.46% increase in the carbonyl and malondialdehyde contents, respectively. Ice crystal formation disrupted the structural integrity of the muscle tissue. Low-field nuclear magnetic resonance results showed that the freeze–thaw cycles prolonged the relaxation times (T2b, T21 and T22), indicating that immobile water shifted to free water, and consequently, free water mobility increased. After 3 freeze–thaw cycles, the decline in shear force slowed, the increase in thawing loss became accelerated, and the TAC approached the domain value (6 log colony-forming units/g). Therefore, the number of freeze–thaw cycles of smooth muscle during transport, storage and distribution should be controlled to 3 or fewer. The current results provide a theoretical basis and data support for the further utilisation and culinary processing of smooth muscle.  相似文献   
8.
He  Mingli  Zhang  Guang  Hu  Shaohua  Zhang  Ying  Wang  Cheng 《Fire Technology》2022,58(5):2755-2778
Fire Technology - A co-flow water mist system is considered a clean and efficient emergency handling measure for preventing and controlling the leakage of hazardous gas. To reveal the coupling...  相似文献   
9.
为了解汉江上游干支流沉积物细菌多样性以及确定性过程和随机性过程在沉积物细菌群落构建过程中的相对重要性,基于Illumina高通量测序技术,分析了环境因子对细菌群落组成的影响,采用非度量多维尺度(NMDS)排序探究了季节之间沉积物细菌群落的差异,并结合中性群落模型和标准化随机率量化了确定性过程和随机过程对群落构建的影响。结果表明:汉江上游及其支流细菌群落主要由变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、蓝藻门(Cyanophyta)、浮霉菌门(Planctomycetes)和酸杆菌门(Acidobacteria)等组成;细菌群落在不同季节有显著差异;地理距离和环境因子对细菌群落结构影响较小,确定性过程并未在细菌群落组成中起到主导作用;随机过程很大程度上影响了群落在秋季和春季的组成,是沉积物细菌群落构建的主导因素。  相似文献   
10.
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