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   421篇
  免费   0篇
化学工业   8篇
能源动力   1篇
无线电   1篇
一般工业技术   1篇
冶金工业   409篇
自动化技术   1篇
  2018年   1篇
  2010年   1篇
  2005年   4篇
  2003年   2篇
  2002年   1篇
  2000年   1篇
  1999年   10篇
  1998年   130篇
  1997年   63篇
  1996年   50篇
  1995年   19篇
  1994年   22篇
  1993年   21篇
  1992年   7篇
  1991年   5篇
  1990年   7篇
  1989年   7篇
  1988年   8篇
  1987年   6篇
  1986年   3篇
  1985年   3篇
  1984年   1篇
  1981年   3篇
  1980年   4篇
  1978年   1篇
  1977年   11篇
  1976年   27篇
  1975年   3篇
排序方式: 共有421条查询结果,搜索用时 15 毫秒
21.
This report includes data on insertions of Lippes Loop D, Copper-7, and Copper-T intrauterine devices (IUDs) performed by certified nurse-midwives and physicians with comparable levels of training and experience in inserting IUDs. Net 1-year pregnancy, expulsion, and removal rates were used to compare the experiences of the 2 groups. There were no significant differences between the groups in most of the event rates or in the overall method discontinuation rates. The authors conclude that, with adequate training and experience, nurse-midwives can provide this family planning service with no additional risk to patients.  相似文献   
22.
23.
24.
The human placental alkaline phosphatase (PLAP) gene was analysed for its utility as a histochemically detectable reporter gene in transgenic mice. A reporter gene was made by linking the PLAP structural gene to an enhancer-promoter element from the human beta-actin gene. This gene was inserted into the mouse genome by transfection of embryonic stem cells, and by microinjection of fertilized eggs. Histochemical staining showed that the transgene was uniformly expressed in four of four stable ES cell lines, and in all ten tissues examined from adult animals from five lines of transgenic mice. Non-transgenic cells did not stain. These results suggest that the human PLAP gene will be of utility in studies requiring phenotypic marking of cells in tissues of mice.  相似文献   
25.
26.
27.
The authors report their clinical observations of 44 patients, aged from 2 months to 14 years, with acute pulmonary abscesses. As evidenced by the authors a roentgenological examination in dynamics is of great value in establishing the diagnosis of pulmonary abscess, since it makes possible to follow the destruction of lung tissues and the formation of cavities. For treatment of lung abscesses different methods were employed: toilet bronchoscopy with antibiotics perfusion, puncture and drainage of the abscess, in case of pulmonary hemorrhage a resection of the lung portion involved, the complex conservative therapy.  相似文献   
28.
1. Rates and rate coefficients of glucose utilization and replacement in post-absorptive rats, either conscious or under halothane anaesthesia, were determined in a thermoneutral environment by using [5-3H]- and [U-14C]glucose. Label was not injected into rats under halothane until about 0.5h after anaesthesia was initiated. 2. Comparison with the results for 24h-starved rats in the preceding paper [Heath et al. (1977) Biochem. J. 162, 643-651] showed that insulin concentrations were considerably higher but rate coefficients for glucose utilization were little altered in post-absorptive rats. Sensitivity to insulin was thus considerably increased by a 24h period of starvation in the rat. 3. Fractional recycling of glucose carbon in post-absorptive rats was under one-half of that in starved rats, reflecting the larger contribution of liver glycogenolysis to glucose production in the former. 4. In post-absorptive rats halothane decreased the mean rate of glucose utilization by about 17%. This decrease was associated with an increase in mean plasma insulin concentration, showing that halothane decreased sensitivity to insulin. 5. Recycling was slightly increased by halothane, indicating that the contribution of liver glycogen to the total glucogenic rate was decreased, probably because liver glycogen concentration were about 40% lower throughout the rate determinations in halothane. 6. Comparison of our results with earlier work shows that during and shortly after induction of halothane anaesthesia glucose turnover must have been greatly increased whereas from about 0.5h after induction it was decreased.  相似文献   
29.
This study examined the effects of client and therapist sex on client self-disclosure and improvement from individual psychotherapy. Based upon closing summary data collected at a college psychological counseling center, it was found that clients were more likely to be rated as low disclosers by female than by male therapists. Males viewed more clients as improved than did females (74% vs. 50%).  相似文献   
30.
Urodynamic pressure measurements using catheters have been widely used among clinicians. More often objective interpretation of urodynamic pressure measurements requires fundamental understanding of pressure measurement techniques due to many measurement artifacts. In this study we developed a simplified compound thick-walled cylinder model to investigate the mechanical nature of urodynamic pressure measurement as well as pressure transmission. Efficacy of collagen implantation was also explored. Lamé's formulation was used to find analytical solutions. Pressure transmission can be related to catheter caliber and the compressibility of the urethral tissue (poisson ratio) in a simple mathematical form. The theoretical pressure transmission ratio will be 133% with the additional incompressibility assumption, reflecting the passive structural transmission of intraabdominal pressure increase. The relationship between the pressure measurement error and the catheter caliber was found to be linear (r2 = 0.94 +/- 0.04) and two or more pressure measurements need to be used to find the uninstrumented pressure. It was predicted that collagen implantation treatment might improve the pressure transmission ratio maximally by 33%.  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