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   5644篇
  免费   208篇
  国内免费   6篇
电工技术   73篇
综合类   3篇
化学工业   874篇
金属工艺   128篇
机械仪表   229篇
建筑科学   94篇
矿业工程   1篇
能源动力   143篇
轻工业   339篇
水利工程   13篇
石油天然气   1篇
无线电   692篇
一般工业技术   791篇
冶金工业   2035篇
原子能技术   43篇
自动化技术   399篇
  2023年   43篇
  2022年   57篇
  2021年   83篇
  2020年   74篇
  2019年   78篇
  2018年   109篇
  2017年   116篇
  2016年   128篇
  2015年   107篇
  2014年   160篇
  2013年   259篇
  2012年   233篇
  2011年   306篇
  2010年   211篇
  2009年   229篇
  2008年   211篇
  2007年   171篇
  2006年   184篇
  2005年   144篇
  2004年   146篇
  2003年   121篇
  2002年   103篇
  2001年   96篇
  2000年   82篇
  1999年   112篇
  1998年   654篇
  1997年   367篇
  1996年   282篇
  1995年   150篇
  1994年   124篇
  1993年   141篇
  1992年   39篇
  1991年   45篇
  1990年   33篇
  1989年   48篇
  1988年   29篇
  1987年   31篇
  1986年   24篇
  1985年   32篇
  1984年   9篇
  1982年   15篇
  1981年   23篇
  1980年   20篇
  1979年   6篇
  1978年   7篇
  1977年   62篇
  1976年   125篇
  1975年   5篇
  1974年   5篇
  1973年   6篇
排序方式: 共有5858条查询结果,搜索用时 0 毫秒
41.
An accurately tuned low-voltage linear continuous-time filter is presented in this paper. Accurate tuning is achieved using time-constant matched master-slave tuning combined with power-up mismatch calibration. A low-pass biquad designed for a corner frequency of 115 kHz achieves better than -80-dB total harmonic distortion with a 250-mV/sub pp/ 10-kHz input signal. The prototype implemented in 0.18-/spl mu/m CMOS process occupies an area of 0.4 mm/sup 2/ and dissipates 4.6 mW (2.6 mW for the filter and 2 mW for tuning) of power.  相似文献   
42.
With the recent advent of accurate orbital volume assessment by computed tomography, a retrospective analysis was made of 31 patients with 'pure' blowout fracture of the orbital floor, managed either surgically or conservatively, to determine whether orbital volume measurement could provide an additional parameter of use in the management of such fractures. There was a significant difference in orbital volume discrepancy between patients managed surgically or conservatively suggesting that this investigation may be of use in decision making on surgical intervention in patients with orbital blowout fractures.  相似文献   
43.
Precusors to the YBa2Cu3O7-δ material were prepared by both the oxalate precipitation method and conventional ceramic processing. Second-phase grains were observed to develop on the exposed fracture surface during annealing at 500° to 600°C in an ambient atmosphere. The second-phase grains were identified to be BaCO3 using EDX and XRD. The liquid phase, which was formed because of local chemical inhomogeneity in the Y-Ba-Cu-O system, contributed to the formation of second-phase grains as a source of Ba.  相似文献   
44.
45.
Fifteen to 20 wt % polyetherimide (PEI) solutions with 1-methyl-2-pyrrolidinone (NMP) were prepared. The electrical conductivity and surface tension of the solutions were determined. The fiber spinning technique of electrospinning was optimized in order to prepare unidirectionally aligned, structurally oriented nanofiber tows. The morphology of the PEI fibers was investigated using field emission scanning electron microscopy (FESEM). The well-aligned fibers with diameters between 0.58 and 0.90 μm (FESEM) were collected by electrospinning 20 wt % PEI solutions with NMP in the range of 8–10 kV onto a target rotating with a surface velocity 9.8 m/s. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   
46.
47.
More inpatient hospital days are used for the care of diabetic foot infection than for any other diabetic sequela. Both the number of lower extremity amputations and the overall treatment cost of treating diabetic infections may be reduced by using a team approach in the care of the infected diabetic pedal wound. The authors propose an evaluation and treatment protocol of infected pedal ulcerations in an urban, community teaching institution when admitted to an established, multidisciplinary diabetic foot care team. The hospital course of 111 patients admitted with a primary diagnosis of infected pedal ulceration are retrospectively reviewed. Results revealed an average-length hospital stay of 7.4 days with a 96% limb-salvage rate. The authors suggest that in the treatment of the infected pedal wound, a diabetic foot care team with a well developed treatment protocol may yield a consistently favorable outcome and a cost-effective hospital course.  相似文献   
48.
Moon 《食品与药品》2006,8(7B):44-46
明眸晧齿,笑容爽朗,脸部轮廓分明。看到袁泉,马上会有清冽甘甜的感觉,一如她的名字,仿佛夏日里活力天然的一泓清泉。从《春天的狂想》到娃哈哈广告中的美丽少女,袁泉给人的印象一直是青春、健康而甜美的,举手投足,一颦一笑,洋溢着独有的耀眼活力。不久前,这位活力闰女更是担任了“中国女性健康白皮书系列活动”的形象大使。作为宣传女性健康的代言人,袁泉呼吁,要让更多的女性认识到:健康的身体才是美丽人生的根基。[编者按]  相似文献   
49.
50.
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