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   2590812篇
  免费   185378篇
  国内免费   7581篇
耳鼻咽喉   34312篇
儿科学   85268篇
妇产科学   71604篇
基础医学   363950篇
口腔科学   69727篇
临床医学   234990篇
内科学   516316篇
皮肤病学   62511篇
神经病学   213857篇
特种医学   99965篇
外国民族医学   736篇
外科学   387068篇
综合类   50413篇
现状与发展   5篇
一般理论   970篇
预防医学   196389篇
眼科学   56715篇
药学   188180篇
  8篇
中国医学   5352篇
肿瘤学   145435篇
  2021年   20220篇
  2019年   20798篇
  2018年   29485篇
  2017年   22730篇
  2016年   26336篇
  2015年   29648篇
  2014年   40598篇
  2013年   60609篇
  2012年   80502篇
  2011年   84739篇
  2010年   51162篇
  2009年   49254篇
  2008年   79194篇
  2007年   83987篇
  2006年   85692篇
  2005年   81870篇
  2004年   78847篇
  2003年   76133篇
  2002年   73425篇
  2001年   128443篇
  2000年   131359篇
  1999年   110516篇
  1998年   31272篇
  1997年   27932篇
  1996年   28228篇
  1995年   27394篇
  1994年   25077篇
  1993年   23427篇
  1992年   85174篇
  1991年   81584篇
  1990年   78800篇
  1989年   76071篇
  1988年   69482篇
  1987年   68010篇
  1986年   63557篇
  1985年   60532篇
  1984年   44960篇
  1983年   37956篇
  1982年   22458篇
  1981年   19992篇
  1979年   38965篇
  1978年   27445篇
  1977年   23260篇
  1976年   21511篇
  1975年   22818篇
  1974年   26795篇
  1973年   25378篇
  1972年   23754篇
  1971年   21956篇
  1970年   20190篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
Although surgical lung resection could improve prognosis in some patients with multidrug-resistant tuberculosis (MDR-TB), there are no reports on the optimal candidates for this surgery. The aim of the present study was to elucidate the prognostic factors for surgery in patients with MDR-TB. Patients who underwent lung resection for the treatment of MDR-TB between March 1993 and December 2004 were included in the present study. Treatment failure was defined as greater than or equal to two of the five cultures recorded in the final 12 months of treatment being positive, any one of the final three cultures being positive, or the patient having died during treatment. The variables that affected treatment outcomes were identified through univariate and multivariate logistic regression analysis. In total, 79 patients with MDR-TB were included in the present study. The treatment outcomes of 22 (27.8%) patients were classified as failure. A body mass index <18.5 kg x m(-2), primary resistance, resistance to ofloxacin and the presence of a cavitary lesion beyond the range of the surgical resection were associated with treatment failure. Low body mass index, primary resistance, resistance to ofloxacin and cavitary lesions beyond the range of resection are possible poor prognostic factors for surgical lung resection in multidrug-resistant tuberculosis patients.  相似文献   
83.
The increased number of lymphocytes in airways during an asthmatic response is believed to be the result of increased recruitment of these cells. However, it is possible that a decreased apoptotic rate could also contribute to the increased number. The aim of the present study was to investigate whether allergen airway provocation influences the apoptotic phenotype of lung and peripheral blood lymphocytes (PBL) in subjects with atopic asthma. Bronchoalveolar lavage (BAL) lymphocytes and PBL from 12 asthmatic subjects previously challenged with allergen (n = 7) or saline (n = 5) were exposed to the apoptotic stimulus tributyltin (TBT) in vitro and assayed for apoptosis. Airway allergen provocation resulted in decreased sensitivity of BAL lymphocytes to TBT-induced apoptosis, with 42.2% (range 33.9-62.5%) apoptotic cells before challenge versus 23.5% (range 15.3-42.4%) after challenge, while PBL were unaffected. The increased apoptosis resistance correlated with higher numbers of Bcl-2-expressing lymphocytes. Interestingly, baseline caspase-3-like activity was significantly elevated in viable BAL lymphocytes compared with viable PBL, and was unaltered by allergen exposure. In conclusion, allergen inhalation renders bronchoalveolar lavage lymphocytes more resistant to apoptosis while peripheral blood lymphocytes were not influenced at all, indicating that the apoptotic phenotype of airway lymphocytes may play a role in asthmatic inflammation.  相似文献   
84.
85.
86.
Neu-Laxova syndrome (NLS) is a rare autosomal recessive syndrome, characterized by severe intrauterine growth retardation (IUGR), microcephaly, abnormal brain development, oedema and ichthyosis. It was first reported in 1971 by Neu et al. (Pediatrics 47: 610-612) and since then no more than 60 cases have been reported. A newborn girl delivered from a 29-year-old healthy mother was admitted to hospital with a thick membrane covering her body and dismorphic appearance. The diagnosis of NLS was made according to characteristic features. The syndrome is known to have a poor prognosis and the baby lived for 9 weeks. This case is one of the longest living cases of NLS and the fourth case reported from Turkey.  相似文献   
87.
The clinical outcome and appropriate management for patients showing 'borderline changes' on allograft biopsy after renal transplantation is still controversial. In an attempt to identify predictive factors of clinical outcome of patients with such lesions, we reviewed the clinical course of 91 patients with borderline changes. Multivariate analysis revealed significant and independent effects of histological stage (i + t < or = or > 2) and time to borderline changes (< or = or > 3 months after transplant) on serum creatinine levels at 1 year from borderline changes episodes (respectively, p = 0.04 and p = 0.02) and only a significant effect of time to borderline changes on serum creatinine levels at 2 years (p = 0.005). Renal function at 1 year and 2 years as 5- and 8-year graft survival were not significantly different in the group of patients treated with antirejection therapy (T group, n = 49) compared with the untreated group (UT group, n = 42). This study strongly suggests that borderline changes with histological score (i + t) > 2 and late episodes of borderline changes should be considered to be of poor prognosis.  相似文献   
88.
89.
90.
Primary chemotherapy administered to breast cancer patientsis the best model to identify baseline features able to predictwhich patients may be most likely to benefit or not from a cytotoxicregimen. In the March issue of Annals of Oncology two papersevaluated the predictive role of immunohistochemical p53 expressionon  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