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   1250篇
  免费   3篇
  国内免费   1篇
化学工业   9篇
金属工艺   5篇
机械仪表   7篇
建筑科学   1篇
轻工业   13篇
无线电   5篇
一般工业技术   7篇
冶金工业   1180篇
原子能技术   17篇
自动化技术   10篇
  2021年   1篇
  2019年   1篇
  2018年   1篇
  2016年   2篇
  2015年   2篇
  2014年   2篇
  2013年   13篇
  2012年   3篇
  2011年   4篇
  2010年   4篇
  2009年   2篇
  2008年   5篇
  2007年   5篇
  2006年   5篇
  2004年   2篇
  2003年   6篇
  2002年   1篇
  2001年   5篇
  2000年   1篇
  1999年   30篇
  1998年   380篇
  1997年   196篇
  1996年   128篇
  1995年   78篇
  1994年   67篇
  1993年   75篇
  1992年   6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   21篇
  1976年   76篇
  1975年   2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1254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.
Carrageenan toxicity was found to vary according to the biochemical nature and source of material injected. Ischaemic lesions of body extremities (acronecrosis) were produced by some but not all preparations. Histological examination of these sites and of both recent and old organ lesions (especially of liver and kidney) confirmed that the underlying pathology was disseminated intravascular coagulation. Evidence was also obtained that carrageenans are hepatotoxic.  相似文献   
6.
Six patients with classical transient ischemic attacks that were not directly related to extracranial carotid disease are presented. These cases were selected to include a variety of pathologic conditions: one case each of brain tumor, arteriovenous malformation, chronic subdural hematoma, cervical spondylosis, and two cases of giant intracranial aneurysms. These case histories are significant because they illustrate that without complete angiographic investigation, tragic results could have and did occur in some cases. Transient ischemic attacks should be considered as a symptom of various possible pathologic conditions, and a careful search for the cause must be pursued aggressively.  相似文献   
7.
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   
8.
In head injured patients changes were found in the CSF levels of metabolites of the dopaminergic and the serotonergic neurotransmission (HVA and 5-HIAA). After the fifth day following trauma a significant decrease of the HVA levels in the lumbar CSF after probenecid treatment was found. The intensity of this decrease was found to be related to the severity of the trauma (period of unconsciousness), but not to the state of consciousness. Also the probenecid-induced 5-HIAA levels in conscious patients were decreased after the fifth post-traumatic day. In unconscious patients, the period of unconsciousness, particularly in the period of 5-20 days after trauma. Between 21 and 60 days after trauma the 5-HIAA concentrations in unconscious patients decreased remarkably, but they were still significantly higher than in the conscious patients. It can be concluded that during unconsciousness serotonergic neurons have a high rate of turnover, but that both neurotransmitter systems are damaged by the direct or indirect consequences of the injury.  相似文献   
9.
The influence of epidural block with bupivacaine (Marcaine-adrenalin) on fetal heart rate, uterine activity, and the frequency and intensity of contractions was studied in twenty-five nulliparae at term. Uterine activity was found to decrease during the first 30 minutes following epidural block. In the time interval 30 to 40 minutes after epidural block uterine activity increased again and attained the same level as during the last 10 minutes before analgesia. The frequency of uterine contractions did not decrease after the block. The lower levels of uterine contractility were due only to a lower amplitude of the contractions. The regularizing effect of epidural analgesia on incoordinate uterine action was noted. The recording of fetal heart rate in the time interval studied revealed no pathological findings. Mode of delivery, mean labour duration and Apgar scores after epidural block were comparable with earlier studies of a larger patient population. This study suggest that epidural analgesia does not induce any important changes in fetal heart rate but temporarily decreases uterine activity.  相似文献   
10.
An industry-wide survey of plasm fractionation facilities in the United States was conducted during 1973-74. Hepatitis was reported among the workers with varying degrees of plasma contact at all plant sites. For each of fourteen facilities in this investigation, field inspections disclosed: (1) numerous overt instances of employee-product contact: (2) inconsistent methodologic approaches at virtually all stages of the plasma fractionation process; (3) at low level of management and employee awareness regarding the potential bio-hazard identified; and (4) disparate examples of hepatitis surveillance and prophylaxis. Our data suggests that there is a high risk of hepatitis among plasma fractionation workers and, as such, much more attention needs to be focused on the reduction of health hazards within this industry.  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