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   11332篇
  免费   1050篇
  国内免费   188篇
耳鼻咽喉   162篇
儿科学   386篇
妇产科学   253篇
基础医学   959篇
口腔科学   503篇
临床医学   1662篇
内科学   2470篇
皮肤病学   256篇
神经病学   737篇
特种医学   311篇
外科学   2437篇
综合类   32篇
一般理论   2篇
预防医学   921篇
眼科学   529篇
药学   416篇
中国医学   48篇
肿瘤学   486篇
  2023年   147篇
  2022年   123篇
  2021年   245篇
  2020年   220篇
  2019年   202篇
  2018年   334篇
  2017年   322篇
  2016年   347篇
  2015年   329篇
  2014年   485篇
  2013年   598篇
  2012年   559篇
  2011年   551篇
  2010年   488篇
  2009年   518篇
  2008年   431篇
  2007年   364篇
  2006年   393篇
  2005年   344篇
  2004年   296篇
  2003年   307篇
  2002年   210篇
  2001年   235篇
  2000年   204篇
  1999年   252篇
  1998年   208篇
  1997年   223篇
  1996年   330篇
  1995年   287篇
  1994年   222篇
  1993年   138篇
  1992年   198篇
  1991年   201篇
  1990年   134篇
  1989年   176篇
  1988年   157篇
  1987年   132篇
  1986年   149篇
  1985年   132篇
  1984年   115篇
  1983年   93篇
  1982年   78篇
  1981年   74篇
  1980年   89篇
  1979年   61篇
  1978年   67篇
  1977年   51篇
  1975年   60篇
  1972年   51篇
  1964年   50篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
BACKGROUND: Abnormalities in calcium and vitamin D metabolism have been reported after bariatric surgery. The purpose of this study was to evaluate vitamin D nutritional status among morbidly obese patients before gastric bypass surgery. METHODS: We prospectively studied 279 morbidly obese patients seeking gastric bypass surgery for vitamin D nutritional status as assessed by serum 25-hydroxyvitamin D level. In addition, serum samples were analyzed for calcium, alkaline phosphatase (AP), intact parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D. RESULTS: Mean patient age was 43 +/- 9 years; 87% of the study patients were women, and 72% were white. Serum calcium and AP levels were normal in 88% and 89% of the patients, respectively. Vitamin D depletion, defined as serum 25-hydroxyvitamin D level 相似文献   
6.
7.
8.
9.
10.
BACKGROUND: The role of local excision for pT2 distal rectal cancer has been challenged because of the observation of high rates of lymph node metastases and local failure. However, neoadjuvant chemoradiation therapy (CRT) has led to increased local disease control and significant tumor downstaging, possibly decreasing rates of lymph node metastases. In this setting, a possible role for local excision of ypT2 has been suggested. METHODS: A total of 401 patients with distal rectal cancer underwent neoadjuvant CRT. Tumor response assessment was performed after at least 8 weeks from CRT completion. One hundred and twelve patients with complete clinical response were not immediately operated on and were excluded from the study, and 289 patients with incomplete clinical response were managed by radical surgery. Patients with final pathological stage ypT2 were analyzed to determine the risk of unfavorable pathological features that could represent unacceptable risk for local failure after local excision. RESULTS: Eighty-eight (30%) patients had ypT2 rectal cancer. Final ypT status was not associated with pretreatment radiological staging (p = 0.62). ypT status was significantly associated with the risk of lymph node metastases, risk of perineural and vascular invasion, and recurrence (p = 0.001). Lymph node metastases were present in 19% of patients with ypT2 rectal cancer. The risk of lymph node metastases in ypT2 was associated with the presence of perineural invasion (47% vs 4%; p = <0.001), vascular invasion (59% vs 6%; p < 0.001), and decreased mean interval CRT surgery (12 vs 18 weeks; p < 0.001), but not with mean tumor size (3.2 vs 3.1 cm; p = 0.8). Disease-free and overall survival rates were significantly better for patients with ypT2N0 (p = 0.02 and 0.006, respectively). Fifty-five (63%) patients with ypT2 had at least one unfavorable pathological feature for local excision (lymph node metastases, vascular or perineural invasion, mucinous type or tumor size >3 cm). CONCLUSION: Lymph node metastases were present in 19% of patients with ypT2 and were significantly associated with poor overall and disease-free survival rates. The risk of lymph node metastases could not be predicted by radiological staging or tumor size. Radical surgery should be considered the standard treatment option for ypT2 rectal cancer after CRT.  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