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   619篇
  免费   28篇
  国内免费   1篇
电工技术   19篇
化学工业   140篇
金属工艺   20篇
机械仪表   15篇
建筑科学   11篇
能源动力   11篇
轻工业   58篇
水利工程   1篇
无线电   64篇
一般工业技术   143篇
冶金工业   104篇
原子能技术   18篇
自动化技术   44篇
  2022年   4篇
  2021年   5篇
  2020年   8篇
  2018年   9篇
  2017年   15篇
  2016年   12篇
  2015年   15篇
  2014年   10篇
  2013年   23篇
  2012年   17篇
  2011年   32篇
  2010年   14篇
  2009年   17篇
  2008年   28篇
  2007年   19篇
  2006年   16篇
  2005年   26篇
  2004年   17篇
  2003年   25篇
  2002年   19篇
  2001年   11篇
  2000年   19篇
  1999年   18篇
  1998年   41篇
  1997年   25篇
  1996年   18篇
  1995年   10篇
  1994年   21篇
  1993年   20篇
  1992年   13篇
  1991年   10篇
  1990年   5篇
  1989年   6篇
  1988年   10篇
  1987年   13篇
  1986年   12篇
  1985年   10篇
  1984年   5篇
  1983年   5篇
  1982年   5篇
  1981年   6篇
  1979年   5篇
  1978年   3篇
  1977年   2篇
  1976年   5篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1970年   2篇
  1967年   2篇
排序方式: 共有648条查询结果,搜索用时 15 毫秒
81.
Room-temperature ring oscillation at 19.6 ps/gate has been accomplished with SAINT FETs using bulk GaAs and implantation. These results have been obtained along with extrinsic resistance reduction and capacitance reduction by taking full advantage of the n+-gate spacing controllability.  相似文献   
82.
83.
84.
GaAs MESFET's with a gate length as low as 0.2 μm have been successfully fabricated with Au/WSiN refractory metal gate n+-self-aligned ion-implantation technology. A very thin channel layer with high carrier concentration was realized with 10-keV ion implantation of Si and rapid thermal annealing. Low-energy implantation of the n+-contact regions was examined to reduce substrate leakage current. The 0.2-μm gate-length devices exhibited a maximum transconductance of 630 mS/mm and an intrinsic transconductance of 920 mS/mm at a threshold voltage of -0.14 V  相似文献   
85.
This study examines one of the largest pedigrees with radial polydactyly type IV (uncomplicated polysyndactyly) comprising a total of 69 individuals, of whom 26 have been affected over six generations. Typical manifestations of the pedigree were bilateral radial and ulnar digital duplications, as well as syndactyly between the middle and ring fingers and the second and third toes. There was no craniofacial anomaly in any of the 17 cases examined physically. This observation suggests that radial polydactyly type IV and Greig craniofacial-synostosis syndrome with similar digital manifestations are clinically-distinct entities.  相似文献   
86.
A rare case of primary pineal melanoma is reported. The patient was a 53-year-old woman who complained of a severe headache. Computed tomography and magnetic resonance images revealed obstructive hydrocephalus caused by a mass lesion in the pineal region. A biopsy was performed through an occipital transtentorial approach. A black pigmented solitary tumor was seen without leptomeningeal dissemination. Histologic examination revealed melanoma. Chemotherapy consisting of dacarbazine, ACNU, vincristine, and interferon was used. Follow-up imaging studies showed dramatic reduction of the tumor without recurrence for 4 years. This report demonstrates that a solitary primary intracranial melanoma without leptomeningeal dissemination and with rare mitoses may yield a good result with chemotherapy.  相似文献   
87.
88.
Bistatic radar cross-section measurements by pendulum method   总被引:1,自引:0,他引:1  
In this paper, the pendulum method for measuring the bistatic radar cross section of a target is proposed, based on the principle of modulated-scattering technique. A modulated wave is formed by swinging the target like a pendulum. This method has the advantages that the measuring procedure is very simple, an absorber-coated room is not required, and the measured value is independent of background waves. Theoretical aspects of the principle are first described, including various kinds of conditions; then the measuring method is given with experimental results.  相似文献   
89.
In the two phase alloys which exhibit superplasticity, strain rate sensitivitym, in the relationship σ = m, has been known to be strongly dependent on the volume fraction of the second phase. It, however, has not been necessarily confirmed experimentally on various two phase alloys. In this paper we present an experimental evidence showing that the largestm is obtained when the volume fraction of the second phase is around 0.5.  相似文献   
90.
Ricin A-chain is delivered into macrophages via receptor-mediated endocytosis. We have found that following uptake via the mannose receptor, ricin A-chain is rapidly cleaved by endosomal proteases. Inhibition of endosomal proteases such as cathepsin D and B leads to the accumulation of toxin inside the cell. Inhibition of cathepsin D reduces ricin A-chain cytotoxicity, while blocking cathepsin B enhances cytotoxicity. Similar results were obtained using fibroblasts transfected with the mannose receptor. Our data strongly suggest that the activation or membrane translocation of ricin A-chain is dependent upon the action of specific proteases.  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