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   1227篇
  免费   3篇
  国内免费   1篇
化学工业   7篇
金属工艺   1篇
机械仪表   6篇
轻工业   15篇
无线电   4篇
一般工业技术   5篇
冶金工业   1186篇
自动化技术   7篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2016年   1篇
  2014年   2篇
  2013年   13篇
  2012年   2篇
  2011年   2篇
  2009年   1篇
  2007年   2篇
  2006年   5篇
  2005年   1篇
  2004年   1篇
  2003年   3篇
  2002年   1篇
  2001年   2篇
  2000年   1篇
  1999年   29篇
  1998年   385篇
  1997年   189篇
  1996年   131篇
  1995年   77篇
  1994年   66篇
  1993年   69篇
  1992年   7篇
  1991年   13篇
  1990年   15篇
  1989年   17篇
  1988年   18篇
  1987年   4篇
  1986年   17篇
  1985年   9篇
  1983年   2篇
  1982年   5篇
  1981年   8篇
  1980年   13篇
  1978年   4篇
  1977年   23篇
  1976年   80篇
  1975年   5篇
  1974年   1篇
  1966年   1篇
  1965年   1篇
  1960年   1篇
  1955年   1篇
排序方式: 共有1231条查询结果,搜索用时 15 毫秒
1.
2.
The Internet technology known as the World Wide Web is rapidly emerging as the most powerful medium of mass communication this century and it can be harnessed to dispense global, cost-effective, high-quality, multimedia patient education material. This paper reviews how the Internet has progressed from delivering simple static, text-based material to sophisticated interactive Web sites based on CGI Technology. Interactive Web sites can be used to deliver health assessment questionnaires and Web-based decision-support systems can give patients advice on the emergency management of acute medical problems. The advantages and drawbacks of this new technology, including information regulation and quality are discussed. The role of the Hospital Intranet as a patient education resource is described. The paper concludes by illustrating how patients can appreciate the 3-D structure of bones and organs using virtual reality in a VRML Web environment.  相似文献   
3.
This article elucidates the clinical applicability and state of the art of ambulatory urodynamics. Ambulatory urodynamics have evolved into practical investigations like EAC, HFM, and EAC combined with renal pelvimetry. EAC has been shown to be the method of preference if detrusor overactivity is involved. Conventional filling cystometry has proved to be an unreliable way to exclude detrusor instability. De novo instability after suspension surgery often indicates that an existing detrusor overactivity was not identified preoperatively. EAC including flowmetry has shown considerable variance in obstructive and contractility parameters in males with LUTS indicative for BPH. This raises doubt whether the clinical flow analysis is the suitable "gold standard" as advocated by the ICS. For a real break through of EAC, less complex automatic analysis is necessary. HFM is a newer method within the range of ambulatory urodynamic tests. It has not yet been completely evaluated. But, because the technique is analogous to the office flowmetry, noninvasive and very well accepted by the patients, it is expected to be widely used. This expectation is strengthened by the fact that HFM seems to show individual therapeutic efficacy of drugs, such as alpha-blockers. As a research tool to evaluate efficacy, it is far more powerful than conventional methods because of the reduction of within-patient standard deviation to about 10%. Finally, EAC combined with pelvimetry offers a promising method for the clinical evaluation of a combined dysfunction of upper and lower urinary tract.  相似文献   
4.
The analysis and synthesis are presented of a non-linear ladder network with diodes incorporated in the series branches. An explicit form of solution is proposed and then applied to the synthesis of piecewise-linear characteristics. An illustrative example is given.  相似文献   
5.
色彩方面的优点氙灯的光线可以提供的优异的色彩,得益于其在可见光波长范围内平坦的光谱输出。其它灯的光谱输出通常带有尖峰,要达到氙灯的光谱输出需要做额外的调整。氙,因为它的光谱输出包含所有颜色,只需较小的或不深的色平衡就可以达到优异的颜色投射和高质量的视觉色调。因此在使用氙灯后,消费者可以看到更好的色彩对比度和优质的图象。氙灯的色温是6500K,汞灯的色温约为8000K。由于最佳的色温是6500K(D65),汞灯的光谱输出需要过滤才能适合这个标准。降低汞灯色温过滤的办法也导致发光效率下降。虽然汞灯比氙灯的效率高得多,但是该必…  相似文献   
6.
7.
Studies were carried out to investigate the role of 1,25(OH)2D3 in the skeletal resistance to the calcemic action of parathyroid hormone. The change in serum calcium after the intravenous infusion of 2 U of parathyroid extract (PTE)/kg body wt/hr for eight hours was evaluated in thyroparathyroidectomized (T-PTX) dogs before, and one, two and three days after, induction of uremia by bilateral ureteral ligation (11 dogs) or by bilateral nephrectomy (8 dogs). In another six nephrectomized and T-PTX dogs, 0.68 ug of 1, 25 (OH)2D3/day was given on the day of nephrectomy and for two days thereafter. Serum creatinine in each day of the study was not different among the three groups. The study also included the evaluation of the effect of sham operation (five dogs) and the administration of 1,25 (OH)2D3 to dogs with normal renal function (four dogs) on the calcemic response to PTE, as well as the reproducibility of such a response in the same animal. The results showed that 1) the calcemic response to PTE was markedly impaired after one day of bilateral ureteral ligation or nephrectomy, but the impairment was more severe after nephrectomy; 2) the calcemic response to PTE after two or three days of bilateral ureteral ligation was similar to that seen at one day after nephrectomy; 3) 1, 25 (OH)2D3 partially restored the calcemic response to PTE in the nephrectomized animals to levels similar to those seen after one day of bilateral ureteral ligation; 4) sham operation did not affect the response to PTE, and repeated infusion of PTE produced similar changes in the concentrations of serum calcium. The data indicate that (a) a deficiency of 1,25 (OH)2D3 is at least partly responsible for the skeletal resistance to the calcemic action of PTH in uremia; (b) uremia, per se, may also contribute to this phenomenon; and (c) the kidney after one day of complete bilateral ureteral ligation may still produce 1,25 (OH)2D3, but this ability is compromised after two days of ureteral obstruction.  相似文献   
8.
9.
Methods for screening and for confirming residues of lincomycin in animal tissues, both sensitive to 0.1 ppm, are described. In the screening technique, residues are extracted, cleaned up by solvent partition, and detected by microbiological plate assay. In the confirmatory technique, residues are cleaned up on an unfunctionalized macroreticular-type resin column, concentrated, chromatographed on thin layer plates, and detected by bioautography. This system was effective in identifying lincomycin in the presence of 20 other antibiotics and chemicals used in the animal health industry.  相似文献   
10.
The body's equilibrium is possible thanks to the integration of skeletal structure, vertebrae, ligaments and muscles to form one functional unity. The forces which determine posture are composed of two complementary systems, the ligamentary and the muscular systems, which together determine a dynamic act of balance. The ligaments operate mainly against the visco-hydraulic pressure of the nucleus pulposus and bind the vertebral bodies together, whereas the muscles exhibit an antigravity function and support spinal stability. A mathematical model based on a mixed theory of directed and oriented curves is proposed. Through this model it is possible to develop an exact theory governing the deformation of the ligamentous spine. This theory should be universal in the sense that it can be used to supply the spine in any of its environments.  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