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   56332篇
  免费   4583篇
  国内免费   2439篇
电工技术   3524篇
技术理论   3篇
综合类   3883篇
化学工业   9167篇
金属工艺   3222篇
机械仪表   3701篇
建筑科学   4462篇
矿业工程   1781篇
能源动力   1663篇
轻工业   3655篇
水利工程   1024篇
石油天然气   3738篇
武器工业   525篇
无线电   6154篇
一般工业技术   6760篇
冶金工业   2505篇
原子能技术   570篇
自动化技术   7017篇
  2024年   96篇
  2023年   989篇
  2022年   1439篇
  2021年   2256篇
  2020年   1896篇
  2019年   1462篇
  2018年   1627篇
  2017年   1802篇
  2016年   1449篇
  2015年   2131篇
  2014年   2829篇
  2013年   3243篇
  2012年   3583篇
  2011年   4031篇
  2010年   3497篇
  2009年   3276篇
  2008年   3213篇
  2007年   2975篇
  2006年   3064篇
  2005年   2560篇
  2004年   1838篇
  2003年   1626篇
  2002年   1599篇
  2001年   1375篇
  2000年   1275篇
  1999年   1503篇
  1998年   1251篇
  1997年   1091篇
  1996年   988篇
  1995年   820篇
  1994年   659篇
  1993年   475篇
  1992年   407篇
  1991年   257篇
  1990年   206篇
  1989年   159篇
  1988年   114篇
  1987年   73篇
  1986年   57篇
  1985年   37篇
  1984年   27篇
  1983年   22篇
  1982年   27篇
  1981年   14篇
  1980年   16篇
  1979年   6篇
  1940年   3篇
  1933年   1篇
  1929年   1篇
  1928年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
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   
6.
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   
7.
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   
8.
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   
9.
10.
何雄元  蒯念生 《广东化工》2022,49(4):170-174,197
化工设备泄漏失效频率数据对化工企业定量风险评估具有重要意义,但目前国内还没有建立相应数据库,在实际应用过程中往往采用国外的数据.介于工业化水平的差异,直接引用国外的数据不够严谨,因此,选取挪威船级社(DNV)公布的数据库为基础,建立合理的修正模型,从而获得适合我国化工行业的通用设备泄漏失效频率数据库,为定量风险评估及设备泄漏概率预测提供数据支撑.  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