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   128508篇
  免费   10660篇
  国内免费   5611篇
电工技术   7889篇
技术理论   11篇
综合类   8419篇
化学工业   20767篇
金属工艺   7257篇
机械仪表   8120篇
建筑科学   10163篇
矿业工程   3803篇
能源动力   3925篇
轻工业   8288篇
水利工程   1992篇
石油天然气   8180篇
武器工业   952篇
无线电   14508篇
一般工业技术   16144篇
冶金工业   6160篇
原子能技术   1469篇
自动化技术   16732篇
  2024年   383篇
  2023年   2134篇
  2022年   3196篇
  2021年   5088篇
  2020年   3819篇
  2019年   3281篇
  2018年   3798篇
  2017年   4204篇
  2016年   3634篇
  2015年   4869篇
  2014年   6093篇
  2013年   7492篇
  2012年   7935篇
  2011年   8677篇
  2010年   7647篇
  2009年   7181篇
  2008年   7209篇
  2007年   6922篇
  2006年   6995篇
  2005年   6150篇
  2004年   4215篇
  2003年   3814篇
  2002年   3716篇
  2001年   3284篇
  2000年   3215篇
  1999年   3555篇
  1998年   2873篇
  1997年   2389篇
  1996年   2352篇
  1995年   1967篇
  1994年   1577篇
  1993年   1186篇
  1992年   963篇
  1991年   736篇
  1990年   532篇
  1989年   421篇
  1988年   371篇
  1987年   226篇
  1986年   163篇
  1985年   137篇
  1984年   91篇
  1983年   51篇
  1982年   71篇
  1981年   43篇
  1980年   38篇
  1979年   21篇
  1977年   7篇
  1976年   8篇
  1975年   5篇
  1951年   6篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Mobile Networks and Applications - Inverse kinematics is an important basic theory in walking control of biped robot. This study focuses on the parameter setting using the improved algorithm in...  相似文献   
2.
3.
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   
4.
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   
5.
Ripe carambolas are hard to store and transport, while freeze-dried ones are easy to store. However, its long production time leads to higher costs. This study shows that high hydrostatic pressure (HHP) treatment could shorten the freeze-drying time of carambola slices. After HHP treatment (25–250 MPa), the drying time of the fresh sample can be shortened by 33.3–44.4% and the distribution of water and pigment in tissues is much uniform. With the increment of the pressure, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rate are increased. At 250 MPa, the total phenolic content (TPC) increased from 11.34 to 13.36 mg GAE g−1, and the total flavonoid content (TFC) of the control sample was increased from 10.77 to 12.73 mg RE g−1. Compared with the untreated sample, HHP treatment can enhance the flavour and shorten the freeze-drying time. This work guides the application of HHP technology for drying food processing.  相似文献   
6.
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   
7.
A digital light processing (DLP) technology has been developed for 3D printing lead-free barium titanate (BTO) piezoelectric ceramics. By comparing the curing and rheological properties of slurries with different photosensitive monomer, a high refractive index monomer acryloyl morpholine (ACMO) was chosen, and a design and preparation method of BTO slurry with high solid content, low viscosity and high curing ability was proposed. By further selecting the printing parameters, the single-layer exposure time was reduced and the forming efficiency has been greatly improved. Sintered specimens were obtained after a nitrogen-air double-step debinding and furnace sintering process, and the BTO ceramics fabricated with 80 wt% slurry shows the highest relative density (95.32 %) and piezoelectric constant (168.1 pC/N). Furthermore, complex-structured BTO ceramics were prepared, impregnated by epoxy resin and finally assembly made into hydrophones, which has significance for the future design and manufacture of piezoelectric ceramic-based composites that used in functional devices.  相似文献   
8.
Pathogens pose a serious challenge to environmental sanitation and a threat to public health.The frequent use of chemicals for sterilization in recent years has not only caused secondary damage to the environment but also increased pathogen resistance to drugs,which further threatens public health.To address this issue,the use of non-chemical antibacterial means has become a new trend for environmental disinfection.In this study,we developed red phosphorus nanoparticles(RPNPs),a safe and degradable photosensitive material with good photocatalytic and photothermal properties.The red phosphorus nanoparticles were prepared using a template method and ultrasonication.Under the irradiation of simulated sunlight for 20 min,the RPNPs exhibited an efficiency of 99.98%in killing Staphylococcus aureus due to their excellent photocatalytic and photothermal abilities.Transmission electron microscopy and ultraviolet–visible spectroscopy revealed that the RPNPs exhibited degradability within eight weeks.Both the RPNPs and their degradation products were nontoxic to fibroblast cells.Therefore,such RPNPs are expected to be used as a new type of low-cost,efficient,degradable,biocompatible,and eco-friendly photosensitive material for environmental disinfection.  相似文献   
9.
10.
Sun  Junli  Wang  Huaibin  Li  Yang  Zhao  Min 《Journal of Porous Materials》2021,28(3):889-894
Journal of Porous Materials - Co3O4 has been widely investigated as a promising candidate anode material for lithium-ion batteries. We report on the porous Co3O4 column synthesized via a simple...  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