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   4363002篇
  免费   340059篇
  国内免费   14739篇
耳鼻咽喉   60333篇
儿科学   139548篇
妇产科学   114283篇
基础医学   667478篇
口腔科学   118009篇
临床医学   397536篇
内科学   792010篇
皮肤病学   107810篇
神经病学   368739篇
特种医学   169680篇
外国民族医学   753篇
外科学   657280篇
综合类   121284篇
现状与发展   24篇
一般理论   2616篇
预防医学   360553篇
眼科学   100931篇
药学   307941篇
  26篇
中国医学   11953篇
肿瘤学   219013篇
  2021年   56282篇
  2020年   35875篇
  2019年   58943篇
  2018年   74513篇
  2017年   57098篇
  2016年   63217篇
  2015年   76216篇
  2014年   110458篇
  2013年   176053篇
  2012年   124718篇
  2011年   129483篇
  2010年   126120篇
  2009年   127836篇
  2008年   115595篇
  2007年   122897篇
  2006年   131690篇
  2005年   125832篇
  2004年   127067篇
  2003年   117266篇
  2002年   106522篇
  2001年   166972篇
  2000年   162041篇
  1999年   148715篇
  1998年   71745篇
  1997年   67648篇
  1996年   65660篇
  1995年   61071篇
  1994年   55010篇
  1993年   51046篇
  1992年   106620篇
  1991年   101389篇
  1990年   97250篇
  1989年   94816篇
  1988年   87146篇
  1987年   85312篇
  1986年   80198篇
  1985年   78354篇
  1984年   65399篇
  1983年   58200篇
  1982年   47191篇
  1981年   43863篇
  1980年   41076篇
  1979年   55105篇
  1978年   44754篇
  1977年   39980篇
  1976年   36841篇
  1975年   36805篇
  1974年   39608篇
  1973年   37750篇
  1972年   35362篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
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   
152.
153.
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   
154.
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   
155.
156.
157.
158.
159.
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   
160.
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