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   5538篇
  免费   78篇
  国内免费   12篇
电工技术   40篇
综合类   5篇
化学工业   389篇
金属工艺   57篇
机械仪表   53篇
建筑科学   116篇
矿业工程   10篇
能源动力   105篇
轻工业   346篇
水利工程   16篇
石油天然气   20篇
无线电   241篇
一般工业技术   346篇
冶金工业   3449篇
原子能技术   24篇
自动化技术   411篇
  2022年   28篇
  2021年   35篇
  2020年   26篇
  2019年   21篇
  2018年   42篇
  2017年   34篇
  2016年   41篇
  2015年   44篇
  2014年   78篇
  2013年   126篇
  2012年   90篇
  2011年   114篇
  2010年   92篇
  2009年   83篇
  2008年   102篇
  2007年   111篇
  2006年   102篇
  2005年   64篇
  2004年   68篇
  2003年   82篇
  2002年   60篇
  2001年   61篇
  2000年   60篇
  1999年   136篇
  1998年   1064篇
  1997年   627篇
  1996年   396篇
  1995年   217篇
  1994年   223篇
  1993年   257篇
  1992年   57篇
  1991年   70篇
  1990年   73篇
  1989年   78篇
  1988年   69篇
  1987年   63篇
  1986年   40篇
  1985年   45篇
  1984年   21篇
  1983年   27篇
  1982年   18篇
  1981年   31篇
  1980年   53篇
  1979年   16篇
  1978年   19篇
  1977年   99篇
  1976年   226篇
  1975年   16篇
  1974年   14篇
  1973年   18篇
排序方式: 共有5628条查询结果,搜索用时 0 毫秒
1.
We determined apolipoprotein E (ApoE) genotypes in 122 autopsied demented patients. The frequency of the ApoE epsilon 4 allele was 39.6% in Alzheimer's disease (AD), 29.0% in the Lewy body variant of AD (LBV), and 6.25% in diffuse Lewy body disease. For AD and LBV patients, the epsilon 4 frequency was significantly higher than that reported in nondemented controls (10 to 15%). Therefore, LBV and AD share ApoE epsilon 4 as a genetic risk factor, providing further evidence that these conditions overlap.  相似文献   
2.
Filtering algorithms are well accepted as a means of speeding up the solution of the consistent labeling problem (CLP). Despite the fact that path consistency does a better job of filtering than arc consistency, AC is still the preferred technique because it has a much lower time complexity. We are implementing parallel path consistency algorithms on multiprocessors and comparing their performance to the best sequential and parallel arc consistency algorithms.(1,2) (See also work by Kerethoet al. (3) and Kasif(4)) Preliminary work has shown linear performance increases for parallelized path consistency and also shown that in many cases performance is significantly better than the theoretical worst case. These two results lead us to believe that parallel path consistency may be a superior filtering technique. Finally, we have implemented path consistency as an outer product computation and have obtained good results (e.g., linear speedup on a 64K-node Connection Machine 2).  相似文献   
3.
4.
Routine poison management involves the following: (1) stabilization, (2) toxidrome recognition, (3) decontamination, (4) antidote administration, (5) enhanced elimination of toxin, and (6) supportive care. Stabilization involves airway, ventilation, and circulation support. In the patient with altered mental status, oxygen, naloxone, glucose, and thiamine should be administered. Symptom complexes that relate to specific classifications of toxins are referred to as toxidromes. Emesis by means of syrup of ipecac is rarely used for in-hospital gastric decontamination. Activated charcoal is a useful adsorbent for gastric decontamination. Whole bowel irrigation is useful for iron, lead, and lithium poisoning and for the body packer phenomenon. Enhancement of elimination may involve multiple doses of activated charcoal, hemodialysis, or charcoal hemoperfusion.  相似文献   
5.
重馏分油加氢脱氮反应动力学模型的研究   总被引:10,自引:1,他引:9  
简要地介绍了一些典型的模型氮化物的HDN反应规律。根据胜利VGO在3722B催化剂上的大量HDN实验数据,提出了如下的HDN基本反应动力学方程:dCNdt=-k1+K*CNCNPH2为了扩大上式的应用范围,详细分析了各种因素(如原料油种类和馏程及H2S等)对HDN的影响,并开发了相应的经验关联式,从而得到了一个较完整的馏分油HDN反应动力学模型。验证实验表明,该模型是成功的。  相似文献   
6.
Patients with extensive damage to the right hemisphere of their brain often exhibit unilateral neglect of the left side of space. The spatial attention of these patients is strongly biased towards the right, so their awareness of visual events on the left is impaired. Extensive right-hemisphere lesions also impair tonic alertness (the ability to maintain arousal). This nonspatial deficit in alertness is often considered to be a different problem from spatial neglect, but the two impairments may be linked. If so, then phasically increasing the patients' alertness should temporarily ameliorate their spatial bias in awareness. Here we provide evidence to support this theory. Right-hemisphere-neglect patients judged whether a visual event on the left preceded or followed a comparable event on the right. They became aware of left events half a second later than right events on average. This spatial imbalance in the time course of visual awareness was corrected when a warning sound alerted the patients phasically. Even a warning sound on the right accelerated the perception of left visual events in this way. Nonspatial phasic alerting can thus overcome disabling spatial biases in perceptual awareness after brain injury.  相似文献   
7.
PURPOSE: We describe a new method of using a Foley catheter to assist vesicourethral anastomosis during radical retropubic prostatectomy. MATERIALS AND METHODS: A total of 81 patients underwent radical retropubic prostatectomy with this technique. Followup ranged from 4 to 48 months. Peri-catheter urethrograms were performed at 3 weeks. Patients were evaluated specifically for bladder neck contracture, urinary continence and prolonged catheterization. RESULTS: Bladder neck contracture, occurred in 4.9% of the patients and 87.6% were completely continent of urine. Only 1 patient required extended postoperative catheterization. CONCLUSIONS: Use of a Foley catheter for vesicourethral anastomosis is consistent and simple, and provided good surgical results in our experience.  相似文献   
8.
9.
Day surgery in urology is in full growth actually. The present report is based on our first 120 patients. Low post-operative complication rate, patients' satisfaction and economical savings are the main factors for the important increase in this type of surgery.  相似文献   
10.
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