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   755110篇
  免费   57556篇
  国内免费   31619篇
电工技术   44065篇
技术理论   83篇
综合类   52660篇
化学工业   121219篇
金属工艺   42068篇
机械仪表   48440篇
建筑科学   61916篇
矿业工程   24262篇
能源动力   20538篇
轻工业   49219篇
水利工程   14366篇
石油天然气   47368篇
武器工业   6112篇
无线电   83333篇
一般工业技术   83228篇
冶金工业   38307篇
原子能技术   7655篇
自动化技术   99446篇
  2024年   1977篇
  2023年   9900篇
  2022年   16833篇
  2021年   26443篇
  2020年   20232篇
  2019年   16485篇
  2018年   19243篇
  2017年   22035篇
  2016年   19882篇
  2015年   27889篇
  2014年   36002篇
  2013年   43571篇
  2012年   47559篇
  2011年   52917篇
  2010年   47025篇
  2009年   44818篇
  2008年   44067篇
  2007年   42589篇
  2006年   43700篇
  2005年   38552篇
  2004年   25819篇
  2003年   22816篇
  2002年   21278篇
  2001年   19276篇
  2000年   19290篇
  1999年   21237篇
  1998年   16836篇
  1997年   14410篇
  1996年   13326篇
  1995年   11155篇
  1994年   9132篇
  1993年   6561篇
  1992年   5167篇
  1991年   3918篇
  1990年   3030篇
  1989年   2471篇
  1988年   1949篇
  1987年   1261篇
  1986年   961篇
  1985年   652篇
  1984年   452篇
  1983年   324篇
  1982年   338篇
  1981年   216篇
  1980年   201篇
  1979年   109篇
  1978年   52篇
  1977年   58篇
  1976年   80篇
  1975年   26篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
31.
Zhang  Nan  Zhao  Man  Liu  Guangfa  Wang  Jiaoyang  Chen  Yunzhi  Zhang  Zhengjian 《Journal of Materials Science》2022,57(19):8687-8700
Journal of Materials Science - A green modification method for effectively enhancing toughness of PLA was established. Herein, alkaline lignin (LG) was firstly alkylated with dodecane, and then...  相似文献   
32.
Wang  Chen  Bao  Chun-Hui  Wu  Wan-Yu  Hsu  Chia-Hsun  Zhao  Ming-Jie  Zhang  Xiao-Ying  Lien  Shui-Yang  Zhu  Wen-Zhang 《Journal of Materials Science》2022,57(26):12341-12355
Journal of Materials Science - Molybdenum oxide (MoOx) films had been grown by using plasma-enhanced atomic layer deposition (PEALD) with Mo(CO)6 precursor and O2 plasma reactant in a substrate...  相似文献   
33.
34.
35.
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   
36.
Yarn-dyed fabric is often woven from warp and weft yarns in the same color depth to ensure a uniform color appearance. The difference in color depth between warp and weft tends to result in the uneven color of the yarn-dyed fabric. This article aims to establish a color tolerance for yarn-dyed fabric that can be woven with a qualified color appearance but from the warp and weft yarns in different color depths. A total of 27 yarn-dyed fabric samples in three color series (red, yellow, and blue) were evaluated by using the yarn-dyed fabric from warp and weft yarns in the same color depth of 2% (on weight of fabric, owf) as the standard. Visual assessment and instrumental measurement of color were carried out to establish the color tolerance ellipse that was defined as CMC (Color Measurement Committee) color differences (2:1) of no more than 1.00. It was found that the color strengths (K/S) and color differences (ΔECMC(2:1)) of these fabric samples for each color series had linear relationships with the color depths of warp and weft yarns. The color tolerance ellipses indicated that, even though the warp and weft yarns had an apparent color difference, they could be woven in fabrics with relatively uniform color appearance and meet the requirements for yarn-dyed fabric. This work provided valuable insight into the production of qualified yarn-dyed fabrics from unqualified dyed yarns.  相似文献   
37.
在医疗卫生、金融证券等应用领域,经常会同时出现零观测值、一观测值较多的情况. 为更好地拟合这类数据,提出0–1膨胀几何分布模型并进行客观贝叶斯分析. 通过参数变换,得到Jeffreys先验和reference先验. 设计后验分布的抽样算法,设置不同的样本量和参数真值,采用数值模拟方法对不同客观先验下的估计效果进行评估.  相似文献   
38.
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   
39.
In this article, we present the optical design of a novel diagnostic on the HL-2 A tokamak, i.e. the20-channel edge Lyman-alpha beam emission spectroscopy, which is a promising solution for edge density turbulence research on tokamaks, as it offers the possibility of density fluctuation measurement with a 3.3 mm spatial resolution while maintains a high temporal resolution of1 μs. The optical path, including the reflective collection optics, the high-dispersion spectrometer, and the linear detector array, is carefully optimized to obtain a good image quality and a high throughput. The maximum root mean square radius of the collection optics is 64 μm.The detected photon flux is estimated to be about 10~(11) photons/s/channel.  相似文献   
40.
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