首页 | 官方网站   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   5134096篇
  免费   385617篇
  国内免费   16226篇
医药卫生   5535939篇
  2021年   57317篇
  2019年   59656篇
  2018年   77191篇
  2017年   59246篇
  2016年   65674篇
  2015年   77919篇
  2014年   112294篇
  2013年   178354篇
  2012年   147756篇
  2011年   156939篇
  2010年   133666篇
  2009年   132560篇
  2008年   141930篇
  2007年   152772篇
  2006年   159543篇
  2005年   153374篇
  2004年   153810篇
  2003年   143134篇
  2002年   131970篇
  2001年   209829篇
  2000年   206557篇
  1999年   184437篇
  1998年   77241篇
  1997年   71293篇
  1996年   69209篇
  1995年   64697篇
  1994年   58561篇
  1993年   54190篇
  1992年   134764篇
  1991年   129184篇
  1990年   124483篇
  1989年   121091篇
  1988年   111308篇
  1987年   108972篇
  1986年   102654篇
  1985年   99849篇
  1984年   80502篇
  1983年   70745篇
  1982年   52354篇
  1981年   48302篇
  1980年   45152篇
  1979年   69662篇
  1978年   54084篇
  1977年   47815篇
  1976年   44316篇
  1975年   45168篇
  1974年   50410篇
  1973年   48330篇
  1972年   45226篇
  1971年   41951篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
152.
On September 11, 2001 two hijacked airplanes struck the Twin Towers at the World Trade Center in New York City. All of the remains (19,915) were examined by the Office of Chief Medical Examiner (OCME) of New York City. The major goals of the OCME were to accurately identify the decedents and to promptly issue death certificates. As of September 2005, there were 1594 identifications of a total of 2749 people reported missing. Of these, 976 were identified by a single means, which included DNA analysis in 852 of the victims. Use of legal statues can assist in the timely issuance of death certificates in mass fatalities, which benefit surviving family members. DNA analysis markedly improves the ability to identify remains and has become the standard method for identification in these types of disasters. Certain postmortem tissue samples are better suited for DNA analysis and yield better results than others.  相似文献   
153.
154.
We have carried out a prospective randomised, single blind clinical trial to investigate the effect of continuous passive motion on range of knee flexion, lack of extension, pain levels and analgesic use after total knee replacement surgery. 85 subjects were randomly allocated to control or study group. All subjects followed the existing rehabilitation protocol, which permits immediate active range of motion exercises and mobilisation with the study group using continuous passive motion for 1 h, twice a day. Outcome measures employed were range of motion, pain assessed on a visual analogue scale and analgesic use according to the WHO ladder. Blinded evaluation was carried out preoperatively, at time of discharge from hospital, 6 weeks, 6 and 12 months postoperation. No significant difference was observed between groups at all time intervals for each outcome variable using Wilcoxon Rank sum tests. The results substantiate previous findings that short duration continuous passive motion following total knee arthroplasty does not influence outcome of range of motion or reported pain.  相似文献   
155.
Fast CT-PRESS-based spiral chemical shift imaging at 3 Tesla.   总被引:2,自引:0,他引:2  
A new sequence is presented that combines constant-time point-resolved spectroscopy (CT-PRESS) with fast spiral chemical shift imaging. It allows the acquisition of multivoxel spectra without line splitting with a minimum total measurement time of less than 5 min for a field of view of 24 cm and a nominal 1.5x1.5-cm2 in-plane resolution. Measurements were performed with 17 CS encoding steps in t1 (Deltat1=12.8 ms) and an average echo time of 151 ms, which was determined by simulating the CT-PRESS experiment for the spin systems of glutamate (Glu) and myo-inositol (mI). Signals from N-acetyl-aspartate, total creatine, choline-containing compounds (Cho), Glu, and mI were detected in a healthy volunteer with no or only minor baseline distortions within 14 min on a 3 T MR scanner.  相似文献   
156.
157.
158.
159.
160.
BACKGROUND: The laparoscopic resection of rectal cancer shows morbidity and oncological safety comparable to the open approach, but morbidity increases after conversion to open resection. No oncological long-term results are available for the latter patients. METHODS: From 01/01/2000-31/12/2002, patients with curatively resected rectal cancer enrolled in a observational study were evaluated for morbidity, mortality, tumor- and local recurrence rate, paying attention to patients with conversion from laparoscopic to open resection. RESULTS: 237 (3.3%) of 7,189 patients underwent laparoscopic resection (ITT). These patients showed significantly more T1/2 tumors (P<0.001) in earlier UICC stages (P<0.001) than open resected patients. 35 (14.8%) of 237 laparoscopic procedures were converted. Compared with patients receiving complete laparoscopic or open resection, these patients showed significantly higher frequencies of intraoperative (P<0.001) and general postoperative complications (P=0.003) as well as the highest overall morbidity (P=0.031). After a median follow-up of 30.1 months, the highest 5-year local recurrence rate was found in the converted group (16.0%). The laparoscopically resected patients showed a local recurrence rate of 3.3%, patients with open resection of 12.4% (P=0.082). The disease-free survival rate did not differ between the groups (P=0.585). CONCLUSION: Laparoscopic resection of rectal cancer provides oncological results similar to open resection. After conversion, the short and oncological long-term outcomes were worse. Considering a conversion rate of 15%, only a strict indication for the laparoscopic approach can be allowed, and laparoscopic resection should be performed at centers.  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-23

京公网安备 11010802026262号