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   1261篇
  免费   1篇
化学工业   12篇
机械仪表   1篇
建筑科学   1篇
能源动力   1篇
轻工业   9篇
石油天然气   1篇
无线电   4篇
一般工业技术   13篇
冶金工业   1215篇
原子能技术   1篇
自动化技术   4篇
  2019年   2篇
  2018年   1篇
  2011年   3篇
  2010年   1篇
  2009年   6篇
  2008年   2篇
  2007年   5篇
  2006年   4篇
  2005年   6篇
  2004年   1篇
  2003年   2篇
  2001年   1篇
  2000年   2篇
  1999年   38篇
  1998年   372篇
  1997年   236篇
  1996年   135篇
  1995年   86篇
  1994年   55篇
  1993年   71篇
  1992年   8篇
  1991年   20篇
  1990年   15篇
  1989年   15篇
  1988年   11篇
  1987年   22篇
  1986年   18篇
  1985年   24篇
  1984年   1篇
  1983年   5篇
  1982年   2篇
  1981年   4篇
  1980年   9篇
  1979年   1篇
  1978年   4篇
  1977年   25篇
  1976年   45篇
  1975年   2篇
  1965年   1篇
  1955年   1篇
排序方式: 共有1262条查询结果,搜索用时 852 毫秒
171.
IQs of rapists were compared to IQs of nonrapist prisoners convicted of violent crimes and nonrapist prisoners convicted of nonviolent crimes. Subjects were 136 male convicted felons in the Kentucky State Penitentiary. Determination of violent vs. nonviolent crimes other than rape was made upon consultation with a Kentucky Commonwealth Attorney. The results revealed significantly lower IQs for rapists compared to nonrapists convicted of violent crimes and compared to heterogeneous nonrapist convicts. The present research supports the findings of Karacan and co-workers, indicating a general tendency for rapists to have lower IQs than other convicted prisoners.  相似文献   
172.
Three experiments examined the influence of videotaped classroom events on the academic performance and study behavior of reading-disabled and normally reading children in grades 1 through 6. In experiments 1 and 2a an experimenter-controlled presentation of these distractors resulted in performance decrements, the magnitude of which was greater for higher difficulty tasks. The distractor effects were similar for the two groups in this condition. However, when the children themselves were allowed to control their degree of exposure to the same distractors in experiment 2b, the reading-disabled children were less likely to act to escape the distraction. Results are discussed in terms of children's metacognitive awareness of distraction, and implications for the classroom are considered.  相似文献   
173.
174.
When rat peroneal nerves were fixed under 5 different fixation schedules with various osmolalities (310, 410 and 900 milliosmoles), the frequency of abnormality of mitochondria in the axoplasm was lowest in myelinated fibers fixed with 6% glutaraldehyde in 0.1 M cacodylate buffer (900 milliosmoles). The relationship of axonal area to number of myelin lamellae was significantly different between high-osmolality fixation and low-osmolality fixation. Assuming that the number of myelin lamellae remains the same with fixation, there was a significant shrinkage in the axonal area of fibers with high-osmolality fixation. The amount of shrinkage was less in larger fibers than in smaller fibers fixed at high osmolality.  相似文献   
175.
176.
177.
The results of PUVA treatment for severe alopecia areata (AA) were reviewed in 102 patients. Fifty-three per cent had greater than 90% regrowth of hair. Although these results appear to be encouraging, they differ little from what would be expected with no treatment. We consider that PUVA is not an effective treatment for AA.  相似文献   
178.
Phenserine ((-)-N-phenylcarbamoyl eseroline), a carbamate analog of physostigmine (Phy), is a long-acting inhibitor of cholinesterase. We have assessed the potential clinical value of phenserine for cholinomimetic therapy of cognitive impairments associated with aging and Alzheimer's disease by evaluating its duration of in vivo activity against rat plasma acetylcholinesterase (AChE) and its effect on attenuating a scopolamine-induced impairment in learning performance of young rats in a shock-motivated 14-unit T-maze. Phenserine achieved maximum AChE inhibition of 73.5% at 5 min and maintained a high and relatively constant inhibition for more than 8 h. For analysis of effects on learning performance, 69, 3-month-old male Fischer-344 rats were pretrained in a straight runway to avoid electric footshock. On the following day, each animal received 15 trials in the 14-unit T-maze. Sixty minutes prior to the maze training, each rat received the first IP injection of either vehicle (Tween 80, ethanol and 0.9% NaCl) or phenserine at 1.5, 3.0, 4.0, 5.0, 7.5, or 10.0 mg/kg. Then 30 min prior to the training, each animal received a second IP injection of either 0.9% NaCl or scopolamine hydrochloride (0.75 mg/kg; SCOP). Compared to the vehicle-SCOP group, all but the 7.5 mg/kg dose of phenserine significantly ameliorated error performance, runtime, shock frequency and shock duration in SCOP-treated rats at the final block of three trials. Appearing to have a long effect and a wide therapeutic window, phenserine deserves further study as a cognitive enhancer.  相似文献   
179.
The antiarrhythmic properties of sublingual verapamil were investigated in seven patients with acute fast atrial flutter (n = 2) or fibrillation (n = 5). A rapid and significant (P < 0.05) reduction in the ventricular rate was achieved in all seven patients. The ventricular rate at peak plasma verapamil concentration (+/- s.d.) was significantly slower than on admission (101.6 +/- 11.3 and 159 +/- 5.3 beats min-1 respectively, P < 0.01). The ventricular rate remained controlled for over 4 h. Sublingual verapamil was rapidly absorbed with the maximum peak plasma concentration (153.3 +/- 15.5 ng ml-1) being achieved after 1.21 +/- 0.18 h. Side-effects of sublingual verapamil were limited to one report of a bitter taste. The sublingual administration of verapamil may provide an alternative method for the control of acute fast atrial fibrillation and flutter in selected patients.  相似文献   
180.
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