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   106723篇
  免费   10353篇
  国内免费   6160篇
电工技术   7418篇
技术理论   7篇
综合类   8559篇
化学工业   16482篇
金属工艺   6158篇
机械仪表   6965篇
建筑科学   8473篇
矿业工程   3046篇
能源动力   3068篇
轻工业   9513篇
水利工程   2358篇
石油天然气   5796篇
武器工业   1119篇
无线电   12103篇
一般工业技术   11397篇
冶金工业   4281篇
原子能技术   1260篇
自动化技术   15233篇
  2024年   410篇
  2023年   1610篇
  2022年   3261篇
  2021年   4360篇
  2020年   3307篇
  2019年   2685篇
  2018年   3036篇
  2017年   3378篇
  2016年   3108篇
  2015年   4423篇
  2014年   5558篇
  2013年   6631篇
  2012年   7552篇
  2011年   8231篇
  2010年   7367篇
  2009年   6989篇
  2008年   7141篇
  2007年   6582篇
  2006年   6257篇
  2005年   5062篇
  2004年   3692篇
  2003年   3495篇
  2002年   3659篇
  2001年   3150篇
  2000年   2348篇
  1999年   2125篇
  1998年   1460篇
  1997年   1243篇
  1996年   1150篇
  1995年   919篇
  1994年   753篇
  1993年   580篇
  1992年   390篇
  1991年   320篇
  1990年   245篇
  1989年   191篇
  1988年   175篇
  1987年   107篇
  1986年   72篇
  1985年   40篇
  1984年   31篇
  1983年   19篇
  1982年   26篇
  1981年   24篇
  1980年   31篇
  1979年   15篇
  1976年   5篇
  1973年   3篇
  1959年   9篇
  1951年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Wan  Huan  Wang  Hui  Scotney  Bryan  Liu  Jun  Ng  Wing W. Y. 《Multimedia Tools and Applications》2020,79(39-40):29327-29352
Multimedia Tools and Applications - In many real-world classification problems there exist multiple subclasses (or clusters) within a class; in other words, the underlying data distribution is...  相似文献   
73.
在广播电视行业不断发展条件下,电视专题节目制作也受到受众高度重视。这就应提高电视专题节目制作质量,在满足广大受众日常观看要求同时,使得我国广播电视行业向着现代化方向发展。针对电视专题节目制作进行研究,首先阐述电视专题节目制作特点,之后阐述电视专题节目制作质量问题和相关提升对策。在解决电视专题节目制作问题同时,提升电视专题节目制作质量,继而彰显电视专题节目制作优势。  相似文献   
74.
75.
In this paper, polyborosilazane precursor was synthesied from HMDZ, HSiCl3, BCl3 and CH3NH2 using a multistep method. By controlling the storage conditions, parts of the polyborosilazane fibers were hydrolyzed. FT-IR, NMR, XRD, TEM and monofilament tensile strength test were employed to study the effects of hydrolysis of precursor on the structures and properties of polymer-derived SiBN ceramic fibers. FT-IR and NMR results indicate that Si-N group in PBSZ reacts with H2O to form Si-O-Si group. After pyrolysis reaction at 1400℃, Si-O-Si group will finally transformed into highly ordered cristobalite and β-quartz, resulting in formation of the wrinkled surface of the obtained SiBN ceramic fiber. The strip-like defects on fiber surface, according to monofilament tensile strength test, had a significant effect on mechanical property of the obtained SiBN ceramic fiber and caused no increase in fiber tensile strength of hydrolytic polyborosilazane fiber before and after pyrolytic process.  相似文献   
76.
77.
78.
In this study, yttrium iron garnet co-doped with Zn and Zr atoms with a chemical formula Y3ZnxZrxFe(5−2x)O12 (x = 0.0-0.3) has been successfully prepared by the solid-state reaction method. The effects of doping concentration on the microstructure, crystal structure, magnetic properties, and dielectric properties of Y3ZnxZrxFe(5−2x)O12 were investigated. The microstructure analysis indicates that co-doping of YIG with Zn and Zr can effectively reduce the grain size of the ceramic. The crystal structure results reveal that the doping concentration of Zn–Zr has substantial influence on the lattice parameters of YIG, such as, increases the lattice constant, crystal cell size, and interplanar spacing. However, the second phase of ZrO2 appears once ≥ 0.15. Additionally, the dielectric properties of YIG ferrite can be regulated using this Zn–Zr co-doping method. Zn–Zr co-doping can improve the dielectric stability and reduce the dielectric loss at high temperature. The magnetization measurement shows that the saturation magnetization is stabilized at x < 0.15, and the magnetic loss is decreased with the increase in the doping concentration. Overall, the findings show that the ceramic with x = 0.1 exhibits better properties included high saturation magnetization (24.607 emu/g), low magnetic loss (0.0025 @ 1 MHz), and relatively low dielectric loss (496 @ 400°C).  相似文献   
79.
80.
Bruton's tyrosine kinase (Btk) is an attractive target for the treatment of a wide array of B-cell malignancies and autoimmune diseases. Small-molecule covalent irreversible Btk inhibitors targeting Cys481 have been developed for the treatment of such diseases. In clinical trials, probe molecules are required in occupancy studies to measure the level of engagement of the protein by these covalent irreversible inhibitors. The result of this pharmacodynamic (PD) activity provides guidance for appropriate dosage selection to optimize inhibition of the drug target and correlation of target inhibition with disease treatment efficacy. This information is crucial for successful evaluation of drug candidates in clinical trials. Based on the pyridine carboxamide scaffold of a novel solvent-accessible pocket (SAP) series of covalent irreversible Btk inhibitors, we successfully developed a potent and selective affinity-based biotinylated probe 12 (2-[(4-{4-[5-(1-{5-[(3aS,4S,6aR)-2-oxo-hexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanamido}-3,6,9,12-tetraoxapentadecan-15-amido)pentanoyl]piperazine-1-carbonyl}phenyl)amino]-6-[1-(prop-2-enoyl)piperidin-4-yl]pyridine-3-carboxamide). Compound 12 has been used in Btk occupancy assays for preclinical studies to determine the therapeutic efficacy of Btk inhibition in two mouse lupus models driven by TLR7 activation and type I interferon.  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