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   2028篇
  免费   361篇
  国内免费   31篇
耳鼻咽喉   9篇
儿科学   45篇
妇产科学   103篇
基础医学   104篇
口腔科学   97篇
临床医学   778篇
内科学   290篇
皮肤病学   45篇
神经病学   170篇
特种医学   41篇
外科学   223篇
综合类   27篇
预防医学   318篇
眼科学   34篇
药学   63篇
中国医学   2篇
肿瘤学   71篇
  2023年   57篇
  2022年   14篇
  2021年   29篇
  2020年   32篇
  2019年   18篇
  2018年   85篇
  2017年   94篇
  2016年   100篇
  2015年   101篇
  2014年   111篇
  2013年   159篇
  2012年   47篇
  2011年   74篇
  2010年   75篇
  2009年   110篇
  2008年   73篇
  2007年   64篇
  2006年   62篇
  2005年   47篇
  2004年   47篇
  2003年   36篇
  2002年   33篇
  2001年   52篇
  2000年   40篇
  1999年   63篇
  1998年   71篇
  1997年   68篇
  1996年   66篇
  1995年   53篇
  1994年   45篇
  1993年   42篇
  1992年   42篇
  1991年   35篇
  1990年   29篇
  1989年   41篇
  1988年   24篇
  1987年   28篇
  1986年   19篇
  1985年   23篇
  1984年   16篇
  1983年   20篇
  1982年   13篇
  1981年   17篇
  1980年   21篇
  1979年   15篇
  1977年   22篇
  1976年   11篇
  1975年   7篇
  1973年   8篇
  1968年   6篇
排序方式: 共有2420条查询结果,搜索用时 15 毫秒
81.
82.
83.
Asthma often starts before six years of age. However, there remains uncertainty as to when and how a preschool-age child with symptoms suggestive of asthma can be diagnosed with this condition. This delays treatment and contributes to both short- and long-term morbidity. Members of the Canadian Thoracic Society Asthma Clinical Assembly partnered with the Canadian Paediatric Society to develop a joint working group with the mandate to develop a position paper on the diagnosis and management of asthma in preschoolers.In the absence of lung function tests, the diagnosis of asthma should be considered in children one to five years of age with frequent (≥8 days/month) asthma-like symptoms or recurrent (≥2) exacerbations (episodes with asthma-like signs). The diagnosis requires the objective document of signs or convincing parent-reported symptoms of airflow obstruction (improvement in these signs or symptoms with asthma therapy), and no clinical suspicion of an alternative diagnosis. The characteristic feature of airflow obstruction is wheezing, commonly accompanied by difficulty breathing and cough. Reversibility with asthma medications is defined as direct observation of improvement with short-acting ß2-agonists (SABA) (with or without oral corticosteroids) by a trained health care practitioner during an acute exacerbation (preferred method). However, in children with no wheezing (or other signs of airflow obstruction) on presentation, reversibility may be determined by convincing parental report of a symptomatic response to a three-month therapeutic trial of a medium dose of inhaled corticosteroids with as-needed SABA (alternative method), or as-needed SABA alone (weaker alternative method). The authors provide key messages regarding in whom to consider the diagnosis, terms to be abandoned, when to refer to an asthma specialist and the initial management strategy. Finally, dissemination plans and priority areas for research are identified.  相似文献   
84.
Summary Seventy-four patients in 1978 and 316 in 1986, all transfused during open-heart surgery in Stockholm, Sweden, were studied prospectively for the development of posttransfusion non-A, non-B (NANB) hepatitis, seroconversion to hepatitis C virus antibodies (anti-HCV) (C-100), time lag to seroconversion to anti-HCV and outcome of posttransfusion NANB/C hepatitis. Anti-HCV was tested up to six months after transfusions in patients from 1978 and up to one year after transfusions in patients from 1986. Fifty-four percent of the patients who developed posttransfusion NANB hepatitis seroconverted to anti-HCV, 7/15 (47%) in 1978 and 8/13 (62%) in 1986. Four (27%) of the 15 patients who seroconverted to anti-HCV were anti-HCV reactive within one week, 12 (80%) within eight weeks and all within 18 weeks after the onset of hepatitis. The ELISA optical density/cut-off (OD/CO) ratio was above 4.0 in all patients with hepatitis C who seroconverted. One transfused patient with normal serum aminotransferase levels throughout follow-up seroconverted after six months. He had a temporary positive anti-HCV reactivity with a maximal ELISA OD/CO ratio for anti-HCV of only 1.2, which became negative three years later. Development of chronic hepatitis was noticed in 9/15 (60%) patients who seroconverted to anti-HCV and in 5/13 (38%) patients with posttransfusion NANB hepatitis who did not seroconvert.
Anti-HBC-Serokonversion bei Patienten mit akuter Non-A, Non-B-Hepatitis nach Transfusion in Schweden
Zusammenfassung 74 Patienten, die 1978, und 316 Patienten, die 1986 während offener Herzchirurgie in Stockholm, Schweden, Transfusionen erhielten, wurden in eine prospektive Studie aufgenommen und im Hinblick auf das Auftreten einer Non-A, Non-B-Posttransfusions-hepatitis, Serokonversion für Hepatitis C Virus-Antikörper (anti-HCV, C-100), Zeitspanne bis zur Serokonversion für anti-HCV und Verlauf der NANB/C-Posttransfusionshepatitis untersucht. Bei Patienten, die 1978 transfundiert worden waren, wurden Untersuchungen auf anti-HCV bis zu sechs Monate nach der Transfusion und bei 1986 Transfundierten bis zu einem Jahr nach Transfusion durchgeführt. Eine Serokonversion zu anti-HCV trat bei 54% der Patienten mit NANB-Posttransfusions-hepatitis ein, 7/15 (47%) der Patienten aus dem Jahr 1978 und 8/13 (62%) aus dem Jahr 1986. Die Serokonversion zu anti-HCV trat bei vier der 15 Patienten (27%) schon innerhalb einer Woche ein, bei 12 (80%) innerhalb acht Wochen und bei allen innerhalb 18 Wochen nach Beginn der Hepatitis. Bei den Patienten mit Hepatitis C, die eine Serokonversion entwickelten, lag der Quotient von ELISA Meßwert zu Grenzwert (Optical density/ Cut-off, OD/CO) in allen Fällen über 4,0. Ein Patient, bei dem nach der Transfusion stets normale Serum- Aminotransferase-Spiegel vorlagen, zeigte nach sechs Monaten eine Serokonversion. Er war vorübergehend anti-HCV positiv, der ELISA OD/CO- Quotient für anti-HCV betrug maximal 1,2; nach drei Jahren war er seronegativ. Bei neun der 15 Patienten (60%) war eine chronische Hepatitis nach Serokonversion für anti-HCV zu beobachten. Unter den 13 Patienten mit NANB-Posttransfusionshepatitis, die keine Serokonversion zeigten, entwickelten fünf eine chronische Hepatitis (38%).
  相似文献   
85.
OBJECTIVES: To determine the effectiveness of pressure bandaging in reducing bleeding and bruising in patients undergoing coronary angiography and to investigate the contribution that pressure bandages make to patient discomfort after angiography.DESIGN: A prospective multicenter, randomized study.SETTING: Three university hospitals in Melbourne, Australia.PATIENTS: One thousand seventy-five patients undergoing coronary angiography were randomized to receive a pressure bandage (N = 556) or no bandage (N = 519) after manual compression of the right femoral artery puncture site.RESULTS: Patients without pressure bandages had a higher incidence of bleeding (P < 0.05) and bled earlier (mean 2.4 hours; SD 3.6 hours) after catheter removal (P < 0.001) than patients with bandages (mean 5.3 hours; SD 3.8 hours). The incidence of bleeding in patients without pressure bandages was 6.7%. The incidence and extent of bruising was the same for both groups. Patients with pressure bandages experienced a higher incidence of back (P < 0.05), groin (P < 0.001), and leg pain (P < 0.001), nausea (P < 0.05), and urinary difficulty (P < 0.01).CONCLUSIONS: In view of the associated increase in patient discomfort and the delay in time of onset of bleeding, pressure bandages should not be used routinely in the management of patients after coronary angiography, especially in the context of early discharge from the hospital.  相似文献   
86.
We determined the effects of an immediately antecedent viral lower respiratory tract infection (LRI) on the severity of clinical illness, changes in lung function and airway histamine responsiveness produced by a subsequent LRI in 9-12 week old beagle puppies inoculated with canine adenovirus 2, followed in 2 weeks by inoculation with canine parainfluenza 2 virus (CAV2-CP12, n = 7). We compared their acute responses to puppies infected with CP12 alone (n = 5), CAV2 alone (n = 7), and no infection (control, n = 6). Puppies inoculated with either virus alone developed a LRI 3 to 6 days after inoculation which resolved by 12-14 days after inoculation. However, the illness was more severe in the CAV2 group. In the CAV2-CP12 group, CP12 infection following CAV2 infection resulted in a clinical illness nearly comparable to that observed with CAV2 alone. Whereas in control and CP12 puppies, lung resistance (RL) decreased and dynamic lung compliance (Cdyn) increased during the study due to normal growth, RL increased and Cdyn remained unchanged in the CAV2 group. In contrast, RL did not change and Cdyn increased in the CAV2-CP12 group. Airway histamine responsiveness in the CAV2-CP12 group increased during infection with CP12 and was similar to that observed with CAV2 alone. In contrast, infection with CP12 alone produced a small, but non-significant increase in histamine responsiveness. The duration of the increase in histamine responsiveness was not prolonged in the CAV2-CP12 group in comparison to CP12 or CAV2 alone. However, the length of clinical illness was extended in the CAV2-CP12 group in comparison to the other infected groups. These data suggest that an immediately antecedent viral LRI can potentiate the clinical and physiologic effects of a subsequent viral LRI.  相似文献   
87.
88.
89.
90.
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