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   3372173篇
  免费   240401篇
  国内免费   8430篇
耳鼻咽喉   45367篇
儿科学   110920篇
妇产科学   94119篇
基础医学   479273篇
口腔科学   93833篇
临床医学   310853篇
内科学   658493篇
皮肤病学   78954篇
神经病学   276047篇
特种医学   128682篇
外国民族医学   964篇
外科学   496012篇
综合类   69056篇
现状与发展   7篇
一般理论   1447篇
预防医学   266028篇
眼科学   75945篇
药学   246105篇
  13篇
中国医学   6468篇
肿瘤学   182418篇
  2019年   26437篇
  2018年   36784篇
  2017年   28350篇
  2016年   32423篇
  2015年   36834篇
  2014年   50723篇
  2013年   76928篇
  2012年   102334篇
  2011年   108564篇
  2010年   64994篇
  2009年   62489篇
  2008年   101944篇
  2007年   108448篇
  2006年   109664篇
  2005年   105771篇
  2004年   101808篇
  2003年   98126篇
  2002年   94834篇
  2001年   156291篇
  2000年   159948篇
  1999年   135101篇
  1998年   39154篇
  1997年   34974篇
  1996年   35424篇
  1995年   34079篇
  1994年   31420篇
  1993年   29473篇
  1992年   106247篇
  1991年   103124篇
  1990年   99913篇
  1989年   96439篇
  1988年   88941篇
  1987年   87162篇
  1986年   82168篇
  1985年   78309篇
  1984年   58900篇
  1983年   50245篇
  1982年   29964篇
  1981年   26933篇
  1979年   53026篇
  1978年   37959篇
  1977年   32209篇
  1976年   29791篇
  1975年   31901篇
  1974年   38011篇
  1973年   36665篇
  1972年   34516篇
  1971年   32089篇
  1970年   29858篇
  1969年   28501篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
992.
993.
994.
BACKGROUND: Although many histopathologic factors in squamous cell carcinoma of the tongue predict the prognosis, the major predictive factors have not been identified clearly. This study analyzed the prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma. METHODS: The clinicopathologic features of 124 consecutive patients seen between January 1985 and December 1999 with previously untreated squamous cell carcinoma of the tongue were reviewed. Their mean age was 58.5 years (range: 23-90) and the male-female ratio was 1.8: 1 (79 men and 45 women). There were 41, 40, 30, and 13 cases at stage I to stage IV, respectively. The clinicopathologic factors, especially the histologic grade at the deep invasive front (invasive front grade, IFG), were analyzed to determine factors predicting prognosis. RESULTS: The 5-year disease-free survival rate of the patients treated with curative aim only was 66.7%. Clinicopathologic factors significantly associated with the prognosis were T classification, tumor size, stage classification, tumor depth, macroscopic appearance, cervical lymph node metastasis (nodal metastasis), microvascular invasion, and IFG. In a multivariate analysis, patients with tumor depth >/=4 mm, IFG >/=8 points, and nodal metastasis had a reduced disease-free survival and IFG >/=11 points had a predictive value for nodal metastasis (odds ratio: 7.34; P = 0.0019). CONCLUSION: This study found that a high IFG malignancy score had a high prognostic value for squamous cell carcinoma of the tongue.  相似文献   
995.
A new approach to the activation of reactants during the condensation of aromatic aldehydes with N-aroylglycines (acting as CH-acids) is described. The condensation reaction carried out on heating in phosphorus oxychloride leads to a high yield of 4-benzylideneoxazol-5-one derivatives. The hydrolysis of these intermediate products yields the target α-benzoylaminocinnamic acids. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 39, No. 7, pp. 41 – 42, July, 2005.  相似文献   
996.
A reply     
M. Harmer 《Anaesthesia》1991,46(9):790-790
  相似文献   
997.
Using Syva EMIT reagents and a Cobas Bio centrifugal analyser we have developed a cost-effective assay for the detection of cannabinoids in urine. With this method, up to 1500 samples can be assayed with a single 100 test kit while maintaining acceptable precision. A mean CV of 6.1% was obtained for the concentration range 80-130 micrograms/l. The method is suitable for high-risk urines since heart treatment may be performed prior to analysis. There was no significant change in the measured concentration of cannabinoids in urine samples on storage in plastic containers, refrigerated or frozen, for up to seven weeks.  相似文献   
998.
We conducted a double blind controlled trial in 28 Duchenne muscular dystrophy (DMD) patients with Deflazacort (DF), an oxazoline derivative of prednisolone which reduces its side-effects. Myometric muscle strength measurements, Scott Score and timed tests showed statistically significant improvement for the treated group (P less than 0.05). Side-effects after 9 months of treatment included mild cushingoid appearance in four patients (28%) and moderate in only one (7%), increased appetite in seven (50%), increased body hair in four (28%), irritability and hyperactivity in three (21%). Increased body weight was not prominent and was controlled with dietary measures. No patient had to be withdrawn from medication. More research and long-term follow-up are needed in order to establish the mechanism of improvement and the consequences of long-term steroid administration in DMD. In this regard DF appears as an alternative to prednisone preserving its benefits but with fewer side-effects.  相似文献   
999.
The sudden appearance of multiple keratoacanthomas in a patient who has sustained a thermal burn is extremely uncommon. This case report describes a sixty-four-year-old man who noted multiple keratoacanthomas within three weeks after being involved in a gasoline explosion. Multiple keratoacanthomas appear to be a rare complication of thermal cutaneous injury in predisposed persons.  相似文献   
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