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   929篇
  免费   2篇
电工技术   2篇
化学工业   43篇
金属工艺   3篇
机械仪表   10篇
建筑科学   4篇
矿业工程   1篇
能源动力   9篇
轻工业   8篇
无线电   17篇
一般工业技术   27篇
冶金工业   775篇
原子能技术   2篇
自动化技术   30篇
  2021年   2篇
  2015年   6篇
  2014年   3篇
  2013年   13篇
  2012年   5篇
  2011年   5篇
  2010年   5篇
  2009年   9篇
  2008年   7篇
  2007年   8篇
  2005年   3篇
  2004年   2篇
  2003年   3篇
  2002年   5篇
  2001年   3篇
  2000年   3篇
  1999年   28篇
  1998年   226篇
  1997年   130篇
  1996年   94篇
  1995年   53篇
  1994年   37篇
  1993年   57篇
  1992年   21篇
  1991年   12篇
  1990年   15篇
  1989年   15篇
  1988年   15篇
  1987年   12篇
  1986年   8篇
  1985年   10篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1981年   8篇
  1980年   7篇
  1979年   5篇
  1978年   3篇
  1977年   21篇
  1976年   40篇
  1975年   1篇
  1974年   4篇
  1973年   3篇
  1972年   1篇
  1971年   3篇
  1970年   3篇
  1966年   1篇
  1965年   1篇
  1958年   2篇
  1955年   1篇
排序方式: 共有931条查询结果,搜索用时 15 毫秒
1.
2.
PURPOSE: Ultrasound estimated bladder weight was compared before and after surgery for benign prostatic hyperplasia (BPH) to reveal a possible reversible change in bladder hypertrophy. MATERIALS AND METHODS: Ultrasound estimated bladder weight was measured before and after subcapsular (17) or transurethral (16) prostatectomy in 33 male patients with BPH. Sequential changes in the American Urological Association symptom score and urinary flow rate were also examined. RESULTS: Along with a significant improvement in the American Urological Association symptom scores and maximum flow rate, ultrasound estimated bladder weight decreased from 52.9 +/- 22.6 to 31.6 +/- 15.8 gm. in 12 weeks after treatment. In all but 4 patients (29 of 33, or 87.9%) ultrasound estimated bladder weight decreased to less than 35.0 gm. in 12 weeks after treatment. Interestingly, in all patients with an initial ultrasound estimated bladder weight of greater than 80 gm. the bladder weight still remained at an abnormally high level 12 weeks after treatment. CONCLUSIONS: Bladder hypertrophy was completely reversible after the surgical treatment of the obstruction in the majority of patients with BPH. The measurement of ultrasound estimated bladder weight was of value in monitoring therapeutic effects in BPH patients. An extraordinarily high ultrasound estimated bladder weight of 80 gm. or more might suggest degenerative and irreversible pathological changes in the bladder detrusor.  相似文献   
3.
4.
5.
6.
7.
8.
9.
10.
MT Massie  MJ Rohrer  JA Leppo  BS Cutler 《Canadian Metallurgical Quarterly》1997,25(6):975-82; discussion 982-3
PURPOSE: Because dipyridamole thallium (DT) scanning is a useful predictor of perioperative cardiac events, a positive results of a DT scan is frequently the basis for performing more invasive cardiac evaluation and for consideration for performing coronary revascularization procedures before performing peripheral vascular surgery. The rationale for this approach has been that the treatment of anatomically significant coronary artery disease would lower the risk of performing a subsequent vascular operation. However, the benefit of performing aggressive diagnostic and therapeutic cardiac procedures in such patients remains unproved. To examine this issue, data from patients who underwent coronary angiography because of thallium redistribution were compared with data from matched control subjects who underwent peripheral vascular operations without further cardiac evaluation. METHODS: The medical records of 70 consecutive patients who underwent coronary angiography because of the presence of two or more segments of redistribution on DT scan were reviewed and compared with 70 other patients matched with respect to age, gender, peripheral vascular operation, and number of segments of redistribution on DT scan who did not undergo additional cardiac evaluation. RESULTS: DT scans were performed on 934 preoperative peripheral vascular surgery patients to help in the assessment of operative risk. Ischemic responses, defined as two or more segments of redistribution, were observed in 297. Of these, 70 underwent cardiac catheterization and 25 underwent coronary revascularization procedures. Adverse outcomes affected 46% of the coronary angiography group and 44% of the control group (p = NS). Patients who underwent coronary angiography and were considered for myocardial revascularization had fewer cardiac events with a subsequent vascular operation than did the control subjects. However, any possible benefit from invasive cardiac evaluation was offset by the three deaths and two myocardial infarctions (MIs) that complicated the cardiac evaluation. There was no significant difference between the angiography group and the matched control subjects with respect to perioperative nonfatal MI (13% vs 9%), fatal MI (4% vs 3%), late nonfatal MI (16% vs 19%), or late cardiac death (10% vs 13%). In long-term follow-up, MIs occurred later in patients who underwent coronary angiography than the control subjects (p = 0.049), but this difference was not associated with an improvement in the overall survival rate. CONCLUSIONS: The risks of extended cardiac evaluation and treatment did not produce any improvement in either the perioperative or the long-term survival rate. For most vascular surgery patients who have a positive result of a DT scan, coronary angiography does not provide any additional useful information.  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