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   574篇
  免费   0篇
化学工业   2篇
金属工艺   1篇
轻工业   2篇
水利工程   6篇
石油天然气   4篇
无线电   3篇
一般工业技术   15篇
冶金工业   501篇
原子能技术   2篇
自动化技术   38篇
  2023年   1篇
  2019年   1篇
  2018年   2篇
  2013年   5篇
  2012年   1篇
  2011年   3篇
  2010年   2篇
  2009年   1篇
  2008年   5篇
  2007年   5篇
  2006年   3篇
  2005年   1篇
  2004年   3篇
  2002年   1篇
  2001年   2篇
  2000年   5篇
  1999年   10篇
  1998年   146篇
  1997年   74篇
  1996年   65篇
  1995年   34篇
  1994年   33篇
  1993年   44篇
  1992年   4篇
  1991年   9篇
  1990年   4篇
  1989年   11篇
  1988年   4篇
  1987年   5篇
  1986年   6篇
  1985年   2篇
  1984年   1篇
  1983年   3篇
  1982年   8篇
  1981年   3篇
  1980年   4篇
  1979年   1篇
  1978年   2篇
  1977年   13篇
  1976年   38篇
  1975年   1篇
  1974年   1篇
  1972年   2篇
  1971年   1篇
  1970年   2篇
  1968年   2篇
排序方式: 共有574条查询结果,搜索用时 0 毫秒
571.
Sixteen young women with hyperprolactinaemia and normal or equivocal sella in radiographs underwent computed tomography using a Siemens Somatom II. In all but one case an abnormality was found. The sella was full in seven and partially empty in nine. A tumour was visible in six of the full and in four of the partially empty sellae. All but one of the 10 tumours was unilateral, and in seven the pituitary stalk was deviated away from the tumour. After administration of intravenous contrast (Urografin) four tumours showed diffuse enhancement, four ring enhancement, and two enhanced less than adjacent normal pituitary tissue. Two of the tumours have been subsequently shown histologically to be prolactinomas. Prolactin response to thyrotrophin-releasing hormone predicted a tumour in seven out of eight with visible tumours but also in three out of four without visible tumours; using metoclopramide, a tumour was predicted in six out of seven with tumours, but again in three out of four without visible tumours. Such results question the value of dynamic tests for the discrimination of tumours. We conclude that practically all women with sustained hyperprolactinaemia and a normal or equivocal sella radiologically have pituitary disease.  相似文献   
572.
NB 《网络与信息》2007,21(2):32-33
网友提问酷睿2T5X X X的技术参数?T5600:2M B二级缓存,1.83G H z主频,667M H z前端总线,支持虚拟化技术;T5500:2M B二级缓存,1.66G H z主频,667M H z前端总线,不支持虚拟化技术;另外,最新推出的T5200是降频“缩水”版本,2M B二级缓存,1.6G H z主频,533M H z前端总线,不支持虚拟  相似文献   
573.
Remote detection of reactive analytes using optical films constructed from electrochemically prepared porous Si‐based photonic crystals is demonstrated. Porous Si samples are prepared to contain either surface oxide or surface Si‐H species, and analyte detection is based on irreversible reactions with HF(aq) or Cl2(g) analytes, respectively. HF dissolves silicon oxide from the porous matrix, causing an irreversible blue‐shift in the resonance peak of the photonic crystal. Cl2 reacts with the native Si‐H species present on the surface of as‐etched porous Si to generate reactive silicon halides that evaporate from the surface and/or react with air to convert to silicon oxide. Either Cl2‐related process reduces the net refractive index of the material that is detected as a blue shift in the spectrum. With sufficient analyte concentrations or exposure times, the spectral blue shifts are visible to the unaided eye. A portion of the porous nanostructure is filled with inert polystyrene, which acts as an internal spectral reference. The polymer fiducial protects that portion of the sensor from attack by the corrosive analytes. Reflectance spectra from both the polymer‐filled and the unfilled, reactive porous layers are acquired simultaneously. The fiducial marker also allows elimination of artifacts associated with shifts of the resonance peak upon changing the angle of incidence of the optical probe. Theoretical angle‐resolved spectra (transfer matrix method) show a good match with the experimental data. High‐temperature air or room‐temperature ozone oxidation reactions are used to prepare the HF‐reactive surface, and it is found that the ozone oxidation reaction produces a greater sensitivity to HF (LLOD of 0.1% HF in water).  相似文献   
574.
Though worker training is often chosen as a means to reduce the risk of low back pain if involved in lifting activities, the effect on a worker's lifting posture is rarely reported. This paper describes a video analysis method of recording lifting postures and the results of one evaluation of a training program specifically designed to modify lifting postures. It is concluded that a four-hour training program had beneficial but minor effects on the lifting techniques used by healthy workers in a warehouse when handling relatively light to moderate loads (i.e., 85% of loads lifted were below 30 pounds).  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