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   2044篇
  免费   1篇
化学工业   11篇
建筑科学   8篇
能源动力   1篇
轻工业   2篇
石油天然气   1篇
一般工业技术   2篇
冶金工业   2016篇
自动化技术   4篇
  2018年   2篇
  2017年   2篇
  2015年   1篇
  2013年   5篇
  2010年   2篇
  2005年   3篇
  2003年   2篇
  2002年   4篇
  2001年   1篇
  2000年   2篇
  1999年   68篇
  1998年   610篇
  1997年   352篇
  1996年   207篇
  1995年   113篇
  1994年   105篇
  1993年   133篇
  1992年   18篇
  1991年   27篇
  1990年   23篇
  1989年   37篇
  1988年   35篇
  1987年   44篇
  1986年   33篇
  1985年   19篇
  1983年   6篇
  1982年   7篇
  1981年   9篇
  1980年   10篇
  1979年   1篇
  1978年   2篇
  1977年   50篇
  1976年   105篇
  1975年   3篇
  1961年   1篇
  1955年   3篇
排序方式: 共有2045条查询结果,搜索用时 31 毫秒
91.
Authors report their results with transcatheter closure of patent arterial duct during a period of 1 year. Thirty patients underwent the procedure at the mean age of 5.22 yrs (range 5 mos-22.3 yrs) and mean bodyweight of 19.1 kg (range 5.8-73 kg). There were 9 males and 21 females. The diagnosis of the patent arterial duct was established by physical examination and noninvasive techniques. The procedures were attempted in all patients above 5 kg bodyweight with patent arterial duct and normal pulmonary artery pressure, irrespective of the shunt-size. All procedures were performed under general anesthesia in one session with the diagnostic cardiac catheterisation. Transcatheter closure was successful in 29 patients. In one patient the device embolized into the left pulmonary artery, snaring was unsuccessful, surgical closure of the patent duct and removal of the device took place uneventfully. Control aortography 15 minutes after the coil placement showed insignificant residual shunt through the patent duct in 8 patients (27%), while echocardiography at 1 month proved complete closure in all. The patients were followed by noninvasive methods. No mortality was observed. Authors emphasize the low risk and cost-effectiveness of the procedure. They stress the importance of the patients selection. Authors applied the technique for the first time and introduced it to the regular patient-care practice in Hungary.  相似文献   
92.
BACKGROUND: During the 9 months between July, 1996, and March, 1997, the provision of euthanasia for the terminally ill was legal in the Northern Territory of Australia. Seven patients made formal use of the Rights of the Terminally Ill (ROTI) Act; four died under the Act. We report their clinical details and the decision-making process required by the Act. METHODS: We taped in-depth interviews with the general practitioner who provided euthanasia. Further information was available from public texts created by patients, the media, and the coroner. FINDINGS: All seven patients had cancer, most at advanced stages. Three were socially isolated. Symptoms of depression were common. Having met criteria of the Act, some patients deferred their decision for a time before proceeding with euthanasia. Medical opinions about the terminal nature of illness differed. INTERPRETATION: Provision of opinions about the terminal nature of illness and the mental health of the patient, as required by the ROTI Act, created problematic gatekeeping roles for the doctors involved.  相似文献   
93.
94.
Pharmacological effects of acute treatment with venlafaxine (VEN), a clinically active antidepressant [a noradrenaline (NA) and 5-hydroxytryptamine (5-HT) reuptake inhibitor without any affinity for neurotransmitter receptors] were studied in mice and rats. VEN inhibited the reserpine- or apomorphine-induced hypothermia and enhanced the L-5-HTP-induced head twitches in mice. It reduced the immobility time in Porsolt's test in mice and rats, but either did not change the locomotor activity (mice) or decreased it (rats). VEN reduced the locomotor hyperactivity induced by amphetamine (AMP), apomorphine (APO) and quinpirole (QUI), as well as the APO-induced stereotypy; the stereotypy induced by AMP in rats was prolonged. VEN neither changed the clonidine-induced aggressiveness in mice nor the behavioral syndrome induced by oxotremorine in rats. The obtained results indicate that VEN, given acutely, shows a pharmacological profile similar to that of tricyclic NA and 5-HT reuptake inhibitors. In contrast to the antidepressants mentioned above, VEN does not exhibit an alpha 1-adrenolytic or a cholinolytic activity (in vivo tests).  相似文献   
95.
OBJECTIVE: Two related studies that evaluated the impact of a continuing education program about community-based rehabilitation on the performance of administrators, professionals, and paraprofessionals are presented. One study contained a second part that examined whether differences between pre-course test performance and post-course test performance might be accounted for by practice effects. DESIGN: Factorial mixed model designs. SETTING: University classroom. PARTICIPANTS: Three hundred and eight professionals, administrators, and paraprofessionals from a variety of community-based rehabilitation programs. INTERVENTION: The 4-day graduate-level course focused on three content areas: brain and behavior relationships, behavioral and cognitive intervention strategies, and a rehabilitation philosophy that emphasizes individual client rights. MAIN OUTCOME MEASURE: An examination completed before and immediately after taking the course. RESULTS: Professionals and administrators perform better than paraprofessionals when tested at the beginning and end of the training. However, the absolute differences among these groups were not substantial. In addition, the rate of learning course content was the same for administrators, paraprofessionals, and professionals. CONCLUSIONS: The results support the usefulness of training for all levels of staff and suggest that all levels of staff benefit in an equal fashion.  相似文献   
96.
97.
OBJECTIVES: The objectives of the study were to assess the suitability of a service for provision of emergency hormonal contraception by nurses. METHODS: Retrospective analysis was carried out of data obtained from the case records of 500 consecutive women who attended ABACUS (a city center-based family planning clinic in Liverpool, UK) for emergency contraception during the 7th and 9th months of the first year (1994) of the service. Similar data were collected for 100 consecutive women during 1 month of the third year (June 1996). The number of women who received emergency hormonal contraception was noted. In particular, details pertaining to the reasons for referral to the doctor and the trend of referrals were noted. RESULTS: The results indicate that during the first year the nurses independently issued emergency hormonal contraception to 37% of the women. They referred the remaining 63% to the medical staff. One-third of referrals were for ongoing contraception, especially oral contraception. Another third of referrals appeared to be due to 'nurse anxiety', as no medical or other cause was found for these referrals. During the third year, nurses dispensed emergency hormonal contraception to 64% of women. Among the remaining 36% of women who were referred to the doctor, 19% needed hormonal contraception. Referral reflecting 'nurse anxiety' significantly declined (1%) compared to the first year of service. CONCLUSIONS: Ongoing contraception, particularly initiation of oral contraception, was one of the main reasons for referral during the first year. Referral due to 'nurse anxiety' significantly declined with continued experience and may have reflected initial anxiety and the learning curve. With increased experience over the first 2 years, the outcome of this service showed encouraging improvement. The nurses now dispense emergency hormonal contraception to a majority of women.  相似文献   
98.
99.
Fifteen Aberdeen Angus steers, 295-364 kg, were dosed with either 4.4 or 11 mg of oxytetracycline hydrochloride/kg im. The antimicrobial activity of the serum was determined periodically, and the resulting data were treated statistically to determine the sources of variation. Variance in serum levels of oxytetracycline activity was attributed to dose, time of bleeding, order of dosing, animal, and assay. The total variance component was proportionately greater for the 11-mg/kg dose than for the 4.4-mg/kg dose. Animal variance increased with the higher dose level of oxytetracycline. The influence of dose on serum level was tested by applying a t test to the mean serum levels and their standard deviations at each bleeding time. The 4.4- and 11-mg/kg serum levels were significantly different (p less than 0.01) at all bleeding times. The 4.4-mg/kg serum levels mutliplied by 2.5 were not significantly different (p less than 0.05) from the 11-mg/kg serum levels at all bleeding times.  相似文献   
100.
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