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   2398篇
  免费   0篇
电工技术   2篇
化学工业   4篇
建筑科学   1篇
轻工业   2篇
石油天然气   2篇
无线电   2篇
一般工业技术   10篇
冶金工业   2374篇
自动化技术   1篇
  2021年   1篇
  2019年   1篇
  2018年   1篇
  2009年   3篇
  2008年   2篇
  2006年   2篇
  2005年   1篇
  2003年   3篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1999年   76篇
  1998年   696篇
  1997年   405篇
  1996年   249篇
  1995年   142篇
  1994年   146篇
  1993年   148篇
  1992年   30篇
  1991年   32篇
  1990年   40篇
  1989年   66篇
  1988年   39篇
  1987年   36篇
  1986年   26篇
  1985年   23篇
  1983年   3篇
  1982年   11篇
  1981年   13篇
  1980年   18篇
  1979年   2篇
  1978年   7篇
  1977年   54篇
  1976年   113篇
  1975年   1篇
  1955年   2篇
排序方式: 共有2398条查询结果,搜索用时 265 毫秒
991.
Sixty ankle arthroscopies were performed on patients with chronic soft-tissue impingement of the ankle after an ankle sprain between January 1989 and January 1994. Preoperative examination findings featured tenderness localized to the anterolateral aspect of the ankle, no instability, and, with the exception of 2 patients, normal radiographs. A preoperative bone scan was performed on 34 patients and was positive in each case but was not specific. Arthroscopy was performed an average of 23 months after injury. Results were determined by using a new ankle rating score. Hypertrophic synovium, synovitis, or fibrous adhesions were arthroscopically visualized and resected in all cases. The average follow-up was 27 months (range, 6 to 64 months). Thirty-one patients underwent complete evaluation and 29 were evaluated over the telephone. There were 51 excellent, 7 good, 1 fair, and 1 poor results. The diagnosis of chronic soft-tissue impingement of the ankle can be made from an appropriate history, thorough physical examination, and plain radiographs. Ankle arthroscopy with resection of impinging hypertrophic synovium or fibrous bands occurring after an ankle sprain was effective in alleviating pain in athletes.  相似文献   
992.
993.
OBJECTIVE: Our purpose was to determine the efficacy and safety of a trial of labor in patients previously delivered at least once by a lower uterine vertical cesarean section. STUDY DESIGN: A retrospective review was performed at a single tertiary perinatal center, The University of Florida Health Science Center, Jacksonville. The medical records of all patients with a previous low vertical cesarean section who underwent a trial of labor during a 72-month period from January 1988 until December 1993 were reviewed. The medical records of the next two patients who did not have a prior uterine incision admitted to labor and delivery after the index case served as the controls. The duration and outcome of labor, including mode of delivery, maternal and perinatal morbidity, and birth trauma were evaluated. RESULTS: Of 77 patients with a previous low vertical cesarean incision, 11 (14.3%) had a repeat operation compared with 14 of 154 patients (9.0%) in the no previous cesarean section group (not significant). No differences were noted in the incidences of operative vaginal deliveries or prolonged duration of the first or second stages of labor, or in the rate or maximum dose of oxytocin infusion between the two groups. One patient in the previous cesarean section group had uterine rupture. The incidence of umbilical artery pH < or = 7.20 was similar. No difference in the number of infants with 1- or 5-minute Apgar scores < or = 7 was noted. CONCLUSION: A trial of labor in women with previous low vertical cesarean sections results in an acceptable rate of vaginal delivery and appears safe for both mother and fetus.  相似文献   
994.
995.
996.
We have compared multiple assays for the P-glycoprotein (Pgp/MDR1) phenotype in fresh and thawed adult acute leukemia to validate and quantitate measures for the expression and function of Pgp. The results are related to the Pgp-expressing KB8 and KB8-5 call lines. The most sensitive assay was the measurement of modulation of the rhodamine 123 (R123) fluorescence by 2 micromol/L PSC833, followed by the modulation of the probe calcein-AM. We also found a good intralaboratory and interlaboratory correlation between the values of the R123/PSC833 assay for fresh as well as thawed samples. In addition, the affects of PSC833 on 3H-daunorubicin (DNR) accumulation, DNR fluorescence, and 3H-vincristine accumulation were very similar. The correlation between the DNR/PSC833 and R123/PSC833 test was r = .86 (N = 51). The modulation of drug accumulation by 8 micromol/L verapamil was the some as the PSC833 effect for DNR (117%, N = 21), but was higher for vincristine in every single case (161% v 121%, N = 22; P< .001), indicating additional verapamil effects, not related to Pgp. The correlation of the staining of viable cells for Pgp with the monoclonal antibody MRK16 was r = .77 (N = 52) for the R123/PSC833 functional test and r = .84 (N = 50) for the DNR/PSC833 test. From these results it could be calculated that a maximal increase of the mean DNR accumulation of about 50% can be achieved by blocking Pgp pump activity with PSC833 in leukemic blast samples with the highest mean Pgp expression. Subpopulations of blast calls with higher Pgp activity are likely to be present. Their relevance has to be studied further. The methods outlined here allow the reliable, quantitative monitoring of the Pgp/MDR1 phenotype in leukemias in multicentered, clinical Pgp modulation studies.  相似文献   
997.
998.
999.
1000.
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