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   2885508篇
  免费   222426篇
  国内免费   9836篇
耳鼻咽喉   40305篇
儿科学   94217篇
妇产科学   76942篇
基础医学   388976篇
口腔科学   75184篇
临床医学   274699篇
内科学   587953篇
皮肤病学   71133篇
神经病学   242652篇
特种医学   110901篇
外国民族医学   743篇
外科学   445976篇
综合类   53773篇
现状与发展   78篇
一般理论   1264篇
预防医学   219301篇
眼科学   63515篇
药学   201479篇
  11篇
中国医学   5632篇
肿瘤学   163036篇
  2021年   24870篇
  2019年   24792篇
  2018年   38185篇
  2017年   30876篇
  2016年   35295篇
  2015年   39025篇
  2014年   57567篇
  2013年   80233篇
  2012年   94988篇
  2011年   100259篇
  2010年   65770篇
  2009年   66426篇
  2008年   94700篇
  2007年   98847篇
  2006年   102050篇
  2005年   96349篇
  2004年   92577篇
  2003年   88290篇
  2002年   85346篇
  2001年   133523篇
  2000年   135486篇
  1999年   115178篇
  1998年   36456篇
  1997年   32618篇
  1996年   32637篇
  1995年   31417篇
  1994年   28030篇
  1993年   25926篇
  1992年   87640篇
  1991年   84067篇
  1990年   80920篇
  1989年   78248篇
  1988年   71398篇
  1987年   69871篇
  1986年   65446篇
  1985年   62316篇
  1984年   46835篇
  1983年   39696篇
  1982年   24383篇
  1981年   21672篇
  1979年   40239篇
  1978年   28711篇
  1977年   24558篇
  1976年   22610篇
  1975年   23848篇
  1974年   27837篇
  1973年   26355篇
  1972年   24594篇
  1971年   22636篇
  1970年   20868篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
B.  Greg  Brown  John  Growley  宋善俊 《美国医学会杂志》2006,25(2):124-126
过去15年来,有关动脉粥样硬化的流行病学、基础生物学和实验研究均支持下述假设:抗氧化剂可通过抑制动脉壁低密度脂蛋白的氧化而抑制动脉粥样硬化的发生。这种作用机制可抑制胆固醇酯通过巨噬细胞清除受体在动脉斑块内发生病理性沉积。胆固醇酯病理沉积是一种可引起斑块破裂及心血管事件的过程。同样,生物机制亦已确定,癌基因可被抗氧化剂阻断。  相似文献   
74.
BACKGROUND: Three dimensional skin equivalents are widely used in dermatopharmacological and toxicological studies and as autologous transplants in wound healing. In pharmacology, there is tremendous need for monitoring the response of engineered skin equivalents to external treatment. Transplantation of skin equivalents for wound healing requires careful verification of their quality prior to transplantation. Optical coherence tomography (OCT) is a non-contact, non-destructive imaging technique for living tissues offering the potential to fulfill these needs. This work presents an analysis of OCT for high-resolution monitoring of skin equivalents at different stages during the culture process. METHODS: We developed a high-resolution OCT imaging setup based on a commercially available OCT system. A broadband femtosecond laser light source replaces the original superluminescence diode. Tomograms of living skin equivalents were recorded with an axial resolution of 3 mum and correlated with histology and immunofluorescence images. Comparison with standard low-resolution OCT is presented to emphasize the advantages of high-resolution OCT for this application. RESULTS: OCT is particularly able to distinguish between different layers of skin equivalents including stratum corneum, epidermal and dermal layer as well as the basement membrane zone. The high-resolution OCT scans correlate closely with two key benchmarks, histology and immunofluorescence imaging. CONCLUSIONS: This study clearly demonstrates the benefits of high-resolution OCT for identifying living tissue structure and morphology. Compared with the current gold standard histology, OCT offers non-destructive tissue imaging, enabling high-resolution evaluation of living tissue morphology and structure as it evolves.  相似文献   
75.
We report the case of a 38-year-old woman who presented with chronic lower abdominal pain. Her past medical history included a splenectomy due to abdominal trauma. Ultrasound examination revealed four pelvic tumors which, upon laparotomy, were found to be the result of splenosis. Approximately 100 cases of splenosis have been reported but only a minority of them have been published in the gynecological literature. Our case indicates that those involved in pelvic scanning (even of asymptomatic women) and/or treating those complaining of lower abdominal pain or presenting with pelvic tumors should be aware of splenosis as a possible diagnosis.  相似文献   
76.
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   
77.
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   
78.
79.
80.
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   
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