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   744167篇
  免费   11961篇
  国内免费   2600篇
电工技术   13095篇
综合类   1031篇
化学工业   111441篇
金属工艺   28078篇
机械仪表   21370篇
建筑科学   18336篇
矿业工程   3469篇
能源动力   20070篇
轻工业   64777篇
水利工程   7573篇
石油天然气   13664篇
武器工业   79篇
无线电   84338篇
一般工业技术   145171篇
冶金工业   145684篇
原子能技术   15674篇
自动化技术   64878篇
  2021年   7005篇
  2020年   5173篇
  2019年   6430篇
  2018年   11112篇
  2017年   11048篇
  2016年   11599篇
  2015年   7947篇
  2014年   13024篇
  2013年   34477篇
  2012年   20783篇
  2011年   28114篇
  2010年   21990篇
  2009年   24644篇
  2008年   25375篇
  2007年   24945篇
  2006年   21581篇
  2005年   19627篇
  2004年   19108篇
  2003年   18756篇
  2002年   17793篇
  2001年   17698篇
  2000年   16475篇
  1999年   17461篇
  1998年   45549篇
  1997年   31838篇
  1996年   24295篇
  1995年   18203篇
  1994年   15964篇
  1993年   15729篇
  1992年   11201篇
  1991年   10620篇
  1990年   10359篇
  1989年   10087篇
  1988年   9366篇
  1987年   8404篇
  1986年   8317篇
  1985年   9172篇
  1984年   8592篇
  1983年   7677篇
  1982年   7263篇
  1981年   7359篇
  1980年   7094篇
  1979年   6799篇
  1978年   6688篇
  1977年   7841篇
  1976年   10471篇
  1975年   5712篇
  1974年   5429篇
  1973年   5564篇
  1972年   4549篇
排序方式: 共有10000条查询结果,搜索用时 287 毫秒
51.
Marrone  Mauricio  Lemke  Sascha  Kolbe  Lutz M. 《Scientometrics》2022,127(7):3857-3878
Scientometrics - Computer-assisted methods and tools can help researchers automate the coding process of literature reviews and accelerate the literature review process. However, existing...  相似文献   
52.
Journal of Materials Science: Materials in Electronics - Nano Mn0.95M0.05S (M ≡ Cu, Mg) samples were produced using molten salt solid state reaction method. Rietveld analysis of X-ray...  相似文献   
53.
Journal of Engineering Physics and Thermophysics - A numerical investigation has been made into the interaction of slender (5–20 calibers) steel cylinder strikers with orthotropic compost...  相似文献   
54.
Journal of Engineering Physics and Thermophysics - Results of investigation into the influence of a corrosion process on thermotechnical characteristics of heat pipes of low-temperature range are...  相似文献   
55.
Deshmukh  P.  Sar  S. K.  Smječanin  N.  Nuhanović  M.  Lalwani  R. 《Radiochemistry》2022,64(4):532-542
Radiochemistry - Magnetically modified waste bark of the Aegle marmelos tree was prepared by using green synthesis method and was used in a batch system for U(VI) removal from aqueous solution. The...  相似文献   
56.
Kamar  M. S.  Shalan  A. S.  Youssef  W. M.  Hussein  A. E. M.  Khawassek  Y. M.  Taha  M. H. 《Radiochemistry》2022,64(2):244-256
Radiochemistry - Ferrugination, sericitization, desulfitization, chloritization, and kaolinitization of hydrothermal origin are the main wall rock alterations occurring within the NNW shear zones...  相似文献   
57.
The present study reports for the first time the performance of silver phosphate (Ag3PO4) microcrystals as photocatalyst (degradation of Rodamine B-RhB) and antifungal agent (against Candida albicansC. albicans) under visible-light irradiation (455 nm). Ag3PO4 microcrystals were synthesized by a simple co-precipitation (CP) method at room temperature. The structural and electronic properties of the as-synthetized Ag3PO4 have been investigated before and after 4 cycles of RhB degradation under visible light using X-ray diffraction (XRD), micro-Raman spectroscopy, UV–Vis spectrophotometer and field emission scanning electron microscopy (FE-SEM) images. The antifungal activity was analyzed in planktonic cells and 48h-biofilm of C. albicans by colony forming units (CFU) counting, confocal laser and FE-SE microscopies. Statistical analysis was carried out using SPSS software. Morphological and structural modifications of Ag3PO4 were observed upon recycling. After 4 recycles, the material maintained its photodegradation property; an eightfold increase in the efficiency of Ag3PO4 was observed in planktonic cells and a two fold increase in biofilm when irradiated under visible light. Thus, higher antifungal effectiveness against C. albicans was obtained when associated with visible-light irradiation.  相似文献   
58.
Extracellular vesicles (EVs) are membranous structures, which are secreted by almost every cell type analyzed so far. In addition to their importance for cell-cell communication under physiological conditions, EVs are also released during pathogenesis and mechanistically contribute to this process. Here we summarize their functional relevance in asthma, one of the most common chronic non-communicable diseases. Asthma is a complex persistent inflammatory disorder of the airways characterized by reversible airflow obstruction and, from a long-term perspective, airway remodeling. Overall, mechanistic studies summarized here indicate the importance of different subtypes of EVs and their variable cargoes in the functioning of the pathways underlying asthma, and show some interesting potential for the development of future therapeutic interventions. Association studies in turn demonstrate a good diagnostic potential of EVs in asthma.  相似文献   
59.
Russian Engineering Research - The modernization of manufacturing by the comprehensive application of digital technology—in both production and management—is considered. Principles are...  相似文献   
60.
Multimedia Tools and Applications - The design of robots capable of operating autonomously in changing and unstructured environments, requires using complex software architectures in which,...  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