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   1075536篇
  免费   72856篇
  国内免费   1365篇
耳鼻咽喉   15021篇
儿科学   34661篇
妇产科学   28642篇
基础医学   153687篇
口腔科学   29563篇
临床医学   95146篇
内科学   204062篇
皮肤病学   24408篇
神经病学   81524篇
特种医学   43025篇
外国民族医学   201篇
外科学   163340篇
综合类   21747篇
现状与发展   1篇
一般理论   263篇
预防医学   74798篇
眼科学   24552篇
药学   86197篇
  7篇
中国医学   2806篇
肿瘤学   66106篇
  2019年   7785篇
  2018年   11318篇
  2017年   8926篇
  2016年   10112篇
  2015年   11278篇
  2014年   15312篇
  2013年   22253篇
  2012年   30620篇
  2011年   32377篇
  2010年   19002篇
  2009年   17864篇
  2008年   30024篇
  2007年   32155篇
  2006年   32782篇
  2005年   31095篇
  2004年   29790篇
  2003年   28611篇
  2002年   27581篇
  2001年   60068篇
  2000年   61512篇
  1999年   50985篇
  1998年   12460篇
  1997年   11026篇
  1996年   11030篇
  1995年   10332篇
  1994年   9363篇
  1993年   8873篇
  1992年   37829篇
  1991年   36314篇
  1990年   35789篇
  1989年   34324篇
  1988年   30911篇
  1987年   30037篇
  1986年   28248篇
  1985年   26483篇
  1984年   19209篇
  1983年   16136篇
  1982年   8834篇
  1979年   17055篇
  1978年   11437篇
  1977年   10242篇
  1976年   8859篇
  1975年   10084篇
  1974年   11664篇
  1973年   11280篇
  1972年   10761篇
  1971年   10101篇
  1970年   9255篇
  1969年   8944篇
  1968年   7930篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Rhinovirus (RV) infections are linked to the development and exacerbation of allergic diseases including allergic asthma. IgE, another contributor to atopic disease pathogenesis, has been shown to regulate DC antiviral functions and influence T cell priming by monocytes. We previously demonstrated that IgE-mediated stimulation of monocytes alters multiple cellular functions including cytokine secretion, phagocytosis, and influenza-induced Th1 development. In this study, we investigate the effects of IgE-mediated stimulation on monocyte-driven, RV-induced T cell development utilizing primary human monocyte-T cell co-cultures. We demonstrate that IgE crosslinking of RV-exposed monocytes enhances monocyte-driven Th2 differentiation. This increase in RV-induced Th2 development was regulated by IgE-mediated inhibition of virus-induced type I IFN and induction of IL-10. These findings suggest an additional mechanism by which two clinically significant risk factors for allergic disease exacerbations—IgE-mediated stimulation and rhinovirus infection—may synergistically promote Th2 differentiation and allergic inflammation.  相似文献   
132.
Postoperative pulmonary complications are associated with an increase in mortality, morbidity and healthcare utilisation. The Agency for Healthcare Research and Quality recommends risk assessment for postoperative respiratory complications in patients undergoing surgery. In this hospital registry study of adult patients undergoing non-cardiac surgery between 2005 and 2017 at two independent healthcare networks, a prediction instrument for early postoperative tracheal re-intubation was developed and externally validated. This was based on the development of the Score for Prediction Of Postoperative Respiratory Complications. For predictor selection, stepwise backward logistic regression and bootstrap resampling were applied. Development and validation cohorts were represented by 90,893 patients at Partners Healthcare and 67,046 patients at Beth Israel Deaconess Medical Center, of whom 699 (0.8%) and 587 (0.9%) patients, respectively, had their tracheas re-intubated. In addition to five pre-operative predictors identified in the Score for Prediction Of Postoperative Respiratory Complications, the final model included seven additional intra-operative predictors: early post-tracheal intubation desaturation; prolonged duration of surgery; high fraction of inspired oxygen; high vasopressor dose; blood transfusion; the absence of volatile anaesthetic use; and the absence of lung-protective ventilation. The area under the receiver operating characteristic curve for the new score was significantly greater than that of the original Score for Prediction Of Postoperative Respiratory Complications (0.84 [95%CI 0.82–0.85] vs. 0.76 [95%CI 0.75–0.78], respectively; p < 0.001). This may allow clinicians to develop and implement strategies to decrease the risk of early postoperative tracheal re-intubation.  相似文献   
133.
ABSTRACT

Adolescents and young adults smoke waterpipe tobacco (WT) and cigarillos, at least in part, based on erroneous beliefs that these products are safer than cigarettes. To address this challenge, we used a systematic, three-phase process to develop a health communication campaign to discourage WT and cigarillo smoking among at-risk (tobacco users and susceptible non-users) 16- to 25-year-olds. In Phase 1, we used a national phone survey (N = 896) to determine salient message beliefs. Participants reported constituents (i.e., harmful chemicals) emitted by the products were worrisome. In Phase 2, we developed and evaluated four message executions, with varying imagery, tone, and unappealing products with the same constituents, using focus groups (N = 38). Participants rated one execution highly, resulting in our development of a campaign where each message: (1) identified a tobacco product and constituent in the smoke; (2) included an image of an unappealing product containing the constituent (e.g., pesticides, gasoline) to grab attention; and (3) used a humorous sarcastic tone. In Phase 3, we tested the campaign messages (17 intervention and six control) with a nationally representative online survey (N = 1,636). Participants rated intervention and control messages highly with few differences between them. Exposure to messages resulted in significant increases in all risk beliefs from pre to post (< 0.05). For WT, intervention messages increased beliefs about addiction more than control messages (p < 0.05). This systematic, iterative approach resulted in messages that show promise for discouraging WT and cigarillo use.  相似文献   
134.
135.
136.
Lucio phenomenon is an atypical reaction of leprosy, characterized by vasculitic lesions that can mimic antiphospholipid syndrome (APS) clinically. Distinguishing the two can be difficult as antiphospholipid autoantibodies may be present in patients with leprosy. We report on a 32‐year‐old female patient presenting with a sudden onset of fever, hemorrhagic bullae, and skin necrosis on her lower legs. She was treated for APS due to the presence of antiphospholipid antibodies but had an inadequate response. A skin biopsy revealed thrombotic vasculopathy and necrotizing vasculitis associated with aggregation of foam cells in the perivascular area and subcutis, with acid‐fast bacilli in the histiocytes and blood vessel walls. Direct immunofluorescence showed IgM, C3, and fibrinogen deposition in the superficial and deep dermal blood vessels. The pathology confirmed the diagnosis of Lucio phenomenon, and appropriate therapy was given. It is essential to evaluate the patient comprehensively, including clinical, serological, and pathological aspects, to obtain the correct diagnosis.  相似文献   
137.
Digestive Diseases and Sciences - To determine whether the presence of portal vein thrombosis (PVT) where venous flow within the liver may be altered may delay the diagnosis of HCC and be...  相似文献   
138.

Background and aims

It is not known whether non alcoholic fatty liver disease (NAFLD) is a risk factor for diabetes in non obese, non centrally-obese subjects. Our aim was to investigate relationships between fatty liver, insulin resistance and a biomarker score for liver fibrosis with incident diabetes at follow up, in subjects who were neither obese nor centrally-obese.

Methods and results

As many as 70,303 subjects with a body mass index (BMI) < 25 kg/m2 and without diabetes were followed up for a maximum of 7.9 years. At baseline, fatty liver was identified by liver ultrasound, insulin resistance (IR) by homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.0, and central obesity by waist circumference (waist circumference ≥90 cm (men) and ≥85 cm (women). The Fibrosis-4 (FIB-4 score) was used to estimate extent of liver fibrosis. Cox proportional hazards models adjusted for confounders were used to estimate hazard ratios (aHRs) for incident diabetes. As many as 852 incident cases of diabetes occurred during follow up (median [IQR] 3.71 [2.03] years). Mean ± SD BMI was 22.8 ± 1.8 and 21.7 ± 2.0 kg/m2 in subjects with and without diabetes at follow up. In subjects without central obesity and with fatty liver, aHRs (95% CI) for incident diabetes at follow up were 2.17 (1.56, 3.03) for men, and 2.86 (1.50,5.46) for women. Similar aHRs for incident diabetes occurred with fatty liver, IR and the highest quartile of FIB-4 combined, in men; and there was a non significant trend toward increased risk in women.

Conclusions

In normal weight, non-centrally obese subjects NAFLD is an independent risk factor for incident diabetes.  相似文献   
139.
140.
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