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   67篇
  免费   1篇
电工技术   3篇
化学工业   5篇
机械仪表   1篇
能源动力   2篇
轻工业   3篇
无线电   9篇
一般工业技术   1篇
冶金工业   38篇
自动化技术   6篇
  2021年   1篇
  2015年   1篇
  2013年   1篇
  2012年   1篇
  2011年   2篇
  2009年   1篇
  2008年   1篇
  2007年   1篇
  2005年   1篇
  2003年   1篇
  2002年   3篇
  2000年   1篇
  1999年   3篇
  1998年   8篇
  1997年   12篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1993年   4篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1986年   4篇
  1985年   2篇
  1980年   1篇
  1976年   4篇
  1965年   1篇
排序方式: 共有68条查询结果,搜索用时 0 毫秒
61.
Decreased serum and intracellular levels of magnesium have been reported in patients with migraine. It has been suggested that magnesium may play an important role in the attacks and pathogenesis of headaches. We measured ionized magnesium, cyclic AMP (adenosine monophosphate), and cyclic GMP (guanosine monophosphate) in platelets of patients with migraine, in patients with tension-type headache, and in healthy controls. The platelet level of ionized magnesium from patients with tension-type headache was significantly lower than the levels from the other two groups. The platelet level of cyclic AMP from patients with migraine was higher than those from the other groups. We found no significant differences in the platelet cyclic GMP levels among the three groups. It is suggested that reduced platelet ionized magnesium in patients with tension-type headache is related to abnormal platelet function, and that increased platelet cyclic AMP in patients with migraine is related to alteration of neurotransmitters in the platelet.  相似文献   
62.
We evaluated the usefulness of percutaneous ethanol injection therapy (PEIT) under Carbon dioxide (CO2) contrast enhanced ultrasound sonography (CEUS) guidance during digital subtraction angiography (DSA) in 21 cases of hepatocellular carcinoma (HCC) with 28 nodules that could not be detected by plain (non-contrast enhanced) US (PUS). In all cases of HCC that could not be visualized by PUS, PEIT could be performed successfully under CEUS guidance. Tumor size was below 10 mm in most cases, in 2 cases tumor size was more than 20 mm. Tumor location was roughly divided into 5 areas: just below the diaphragm and it's vicinity, liver surface, edge of the liver, around the portal and hepatic vein, and around the inferior vena cave. The detection rate of the nodules that could not be visualized with PUS was 35.7% for CT and 32.1% for DSA. PEIT was performed 1-9 times for each lesion, 3.32 times on an average. The effectiveness of PEIT was judged by CT. All cases were confirmed as LDA. We concluded that the range of indication of PEIT can be expanded by this method.  相似文献   
63.
In order to extract macroscopic mechanical work out of microelectromechanical systems, we have proposed the concept of distributed micromotion systems (DMMS). The key idea of DMMS is to coordinate simple motions of many microactuators in order to perform a task. Design, fabrication, and operation of a type of DMMS, called a ciliary motion system, are presented. A bimorph thermal actuator using two types of polyimides with different thermal expansion coefficients and a metallic microheater in between them was fabricated. The cantilever-shaped actuator curled up from the substrate owing to the residual stress in polyimides which built up during the cooling process after they were cured at 350°C. It flattened and moved downward by flowing current in the heater. The dimensions of the cantilever were 500 μm in length, 100 μm in width, and 6 μm in thickness. The tip of the cantilever moved 150 μm in the direction vertical to the substrate and 80 μm in the horizontal direction; these were the maximum displacements obtained with 33 mW dissipated in the heater. The cut-off frequency was 10 Hz. On a 1-cm-square substrate, 512 cantilevers were fabricated to form an array. Two sets of cantilevers were placed opposing to each other. We operated them in coordination to mimic the motion and function of cilia and carried a small piece of a silicon wafer (2.4 mg) at 27-500 μm/s with 4-mW input power to each actuator  相似文献   
64.
A 256-Mb DRAM with a multidivided array structure has been developed and fabricated with 0.25-μm CMOS technology. It features 30-ns access time, 16-b I/Os, and a 35-mA operating current at a 60-ns cycle time. Three key circuit technologies were used in its design: a partial cell array activation scheme for reducing power-line voltage bounce and operating current, a selective pull-up data-line architecture to increase I/O width and reduce power dissipation, and a time-sharing refresh scheme to maintain the conventional refresh period without reducing operational margin. Memory cell size was 0.72 μm2. Use of the trench isolated cell transistor and the HSG cylindrical stacked capacitor cells helped reduce chip size to 333 mm2  相似文献   
65.
Mouse epididymal spermatozoa from inbred(BALB/c, C3H/He, C57BL/6N, CBA/JN and DBA/2N) and F1 hybrid (B6C3F1, BDF1 and CDF1) strains suspended in cryopreservation solution (18% raffinose and 3% skim milk in distilled water) were frozen and stored at -196 degrees C. After thawing at room temperature, sperm motility and fertilizing ability were examined. Spermatozoa from all of the strains were successfully frozen, although the motility and the fertilization rates of frozen-thawed spermatozoa (the proportions of the fresh oocytes from Jcl:ICR strain which developed to pronuclear oocytes and 2-cell embryos after insemination by frozen-thawed spermatozoa) varied among strains (motility: 23% for C57BL/6N to 62% for DBA/2N; fertilization rates: 26% for C57BL/6N to 89% for DBA/2N). Nearly all 2-cell embryos fertilized by frozen-thawed spermatozoa were transferred to the oviducts of pseudopregnant recipients and 35-62% of 2-cell embryos developed into normal young.  相似文献   
66.
Volumetric data exploration using interval volume   总被引:2,自引:0,他引:2  
A new type of geometric model called Interval volume for volumetric data exploration is presented. An interval volume represents a three dimensional subvolume for which the associate scalar values lie within a user specified interval, and provides one of the promising approaches to solid fitting, which is an extended concept of traditional surface fitting. A well known isosurfacing algorithm called Marching Cubes is extended to obtain a solid fitting algorithm, which extracts from a given volumetric data set a high resolution, polyhedral solid data structure of an interval volume. Branch-on-Need Octree is used as an auxiliary data structure to accelerate the extraction process. A variety of interval volume rendering methods and principal related operations, including measurements and focusing, are also presented. The effectiveness of measurement coupled visualization capabilities of the presented approach is demonstrated by application to visualizing a four dimensional simulated data from atomic collision research  相似文献   
67.
68.
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