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   116304篇
  免费   11224篇
  国内免费   6493篇
电工技术   8078篇
技术理论   9篇
综合类   10451篇
化学工业   17836篇
金属工艺   6848篇
机械仪表   7471篇
建筑科学   9016篇
矿业工程   3140篇
能源动力   3279篇
轻工业   11167篇
水利工程   2353篇
石油天然气   5768篇
武器工业   1223篇
无线电   12692篇
一般工业技术   12108篇
冶金工业   4307篇
原子能技术   1236篇
自动化技术   17039篇
  2024年   435篇
  2023年   1807篇
  2022年   3618篇
  2021年   4889篇
  2020年   3674篇
  2019年   2963篇
  2018年   3198篇
  2017年   3692篇
  2016年   3232篇
  2015年   4843篇
  2014年   6200篇
  2013年   7167篇
  2012年   8430篇
  2011年   9206篇
  2010年   8354篇
  2009年   7870篇
  2008年   7911篇
  2007年   7393篇
  2006年   7039篇
  2005年   5601篇
  2004年   4154篇
  2003年   3736篇
  2002年   4028篇
  2001年   3337篇
  2000年   2517篇
  1999年   2069篇
  1998年   1428篇
  1997年   1124篇
  1996年   985篇
  1995年   740篇
  1994年   598篇
  1993年   423篇
  1992年   347篇
  1991年   266篇
  1990年   180篇
  1989年   146篇
  1988年   94篇
  1987年   75篇
  1986年   60篇
  1985年   28篇
  1984年   17篇
  1983年   23篇
  1982年   24篇
  1981年   24篇
  1980年   35篇
  1979年   13篇
  1965年   2篇
  1960年   2篇
  1959年   8篇
  1951年   4篇
排序方式: 共有10000条查询结果,搜索用时 796 毫秒
51.
Zu  Guoqing  Lu  Yukuan  Yan  Yi  Zhang  Xiaoming  Zhao  Jingwei  Du  Wei  Ran  Xu  Jiang  Zhengyi 《Metals and Materials International》2020,26(2):248-259
Metals and Materials International - The flow behaviour and microstructure characteristics of a ferritic stainless steel were investigated using plain strain compression test on a Gleeble 3500...  相似文献   
52.
张立祥  闫宣宣 《煤矿机械》2020,41(1):117-119
针对当前KJS-Y系列降尘器效率低的问题,通过调整叶轮轴向间隙与径向间隙参数,分别对不同安装参数的降尘器进行数值模拟,通过数值模拟分析特定截面压力分布情况,确定了叶轮最佳安装参数,大大提高了降尘器的工作效率,同时降低了设计成本。  相似文献   
53.
The relationship between the particle size distribution and the extinguishing effectiveness of the new K‐powder fire extinguishing agent has been studied experimentally, to explore the reason of the great extinguishing efficiency exhibited by the new K‐powder fire extinguishing agent on Class B fire (liquid fuel fire). The results of the experiment showed that the extinguishing effectiveness increased along with the decrease of the particle size distribution. In addition, a sharp discontinuity appeared around the limiting size, about 40 μm. The powder with the particle size below 40 μm exhibited highly effective extinguishing with the minimum effective extinguishing concentration Cxr = 23 g·m?3, while the powder with the particle size above 40 μm exhibited little fire extinguishing efficiency. Compared with other fire extinguishing agents produced by different substances, the new K‐powder fire extinguishing has the bigger limiting size. That means, in the same particle size distribution, the new K‐powder fire extinguishing agent contains more highly effective powder than others contain, and is more effective.  相似文献   
54.
Loss of β-cell mass and function can lead to insufficient insulin levels and ultimately to hyperglycemia and diabetes mellitus. The mainstream treatment approach involves regulation of insulin levels; however, approaches intended to increase β-cell mass are less developed. Promoting β-cell proliferation with low-molecular-weight inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) offers the potential to treat diabetes with oral therapies by restoring β-cell mass, insulin content and glycemic control. GNF4877, a potent dual inhibitor of DYRK1A and glycogen synthase kinase 3β (GSK3β) was previously reported to induce primary human β-cell proliferation in vitro and in vivo. Herein, we describe the lead optimization that lead to the identification of GNF4877 from an aminopyrazine hit identified in a phenotypic high-throughput screening campaign measuring β-cell proliferation.  相似文献   
55.
“Smart firefighting” construction as a part of the “smart city” has been a concern of the public security and fire agencies at all levels. In this study, the status, problems, and reflections of “smart firefighting” construction in China are discussed. A recent survey indicates that China has launched its smart firefighting construction and initially created a new perspective on its regional smart firefighting work based on three main aspects: intelligent disaster perception by Internet of Things (IoT) construction, intelligent disaster prevention by big data construction, and intelligent disaster disposal by emergency rescue platform construction. However, the current smart firefighting construction in China still has some prominent problems such as the data interconnectivity and normalized management of various platforms, the extensibility of smart firefighting platforms, and the intelligent level of smart firefighting researches, which need to be solved urgently. Therefore, we argue that smart firefighting construction in China should establish data interconnectivity, industrial normalized management, 2D/3D geographic information interaction and extension, high-integration fire protection theory, and many other aspects in the near future and truly realize firefighting visualization and efficient data applications for 4D time space. This study could provide valuable reference for smart firefighting and smart city construction.  相似文献   
56.
Protection of Metals and Physical Chemistry of Surfaces - The Al2O3 powder was added as a filler to polyurea and the effect of doping amount on Shore hardness and wetting property were...  相似文献   
57.
The densification behaviors of pure B4C and B4C-ZrO2 mixtures were compared during hot pressing. The results showed that in-situ formed ZrB2 effectively enhanced the densification process of B4C-ZrO2 mixtures, more significantly during the intermediate stage. Within the relative density ranging from 0.75 to 0.90, the B4C-15?wt%ZrO2 mixture (B15Z) achieved the maximum densification rate as twice much as that of pure B4C. The stress exponent n>3 indicated plastic deformation was the dominant densification mechanism of B15Z. The viscosities of plastic flow were evaluated using Murray-Rodger-William equation and the viscosity of B15Z was only a quarter of that in pure B4C. The sintering activation energy was calculated to be 305.9?kJ/mol for pure B4C and 197?kJ/mol for B15Z, respectively. It was proposed that the lower viscosity of plastic flow and activation energy accelerated the sliding and propagating motions of plastic flow, by which underlain the enhanced densification behaviors of B4C-ZrO2 mixtures.  相似文献   
58.
59.
肖艳  肖忠来 《电镀与涂饰》2021,40(18):1410-1415
介绍了一种在不改变原有工艺路线,不需要返线或另建专用套色线就可以实现车身套色的新型工艺,其基本上不受套色车产能比例限制,具有投资少、能耗低、产能柔性程度高等特点.  相似文献   
60.
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