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   915900篇
  免费   74398篇
  国内免费   1977篇
耳鼻咽喉   13495篇
儿科学   26141篇
妇产科学   26446篇
基础医学   132968篇
口腔科学   26949篇
临床医学   80561篇
内科学   175290篇
皮肤病学   17797篇
神经病学   75051篇
特种医学   37457篇
外国民族医学   211篇
外科学   143018篇
综合类   25060篇
现状与发展   2篇
一般理论   335篇
预防医学   71115篇
眼科学   21549篇
药学   68556篇
中国医学   1739篇
肿瘤学   48535篇
  2018年   8346篇
  2015年   8695篇
  2014年   12289篇
  2013年   18814篇
  2012年   25357篇
  2011年   26566篇
  2010年   15767篇
  2009年   14693篇
  2008年   24994篇
  2007年   27152篇
  2006年   27065篇
  2005年   26567篇
  2004年   26126篇
  2003年   25017篇
  2002年   24162篇
  2001年   37510篇
  2000年   38167篇
  1999年   32510篇
  1998年   9983篇
  1997年   9155篇
  1996年   8994篇
  1995年   8538篇
  1994年   8167篇
  1992年   27794篇
  1991年   27192篇
  1990年   26664篇
  1989年   25729篇
  1988年   24103篇
  1987年   23786篇
  1986年   22574篇
  1985年   21840篇
  1984年   16951篇
  1983年   14488篇
  1982年   9218篇
  1981年   8570篇
  1980年   7976篇
  1979年   17223篇
  1978年   12404篇
  1977年   10453篇
  1976年   9555篇
  1975年   10446篇
  1974年   12971篇
  1973年   12413篇
  1972年   11807篇
  1971年   10915篇
  1970年   10415篇
  1969年   10086篇
  1968年   9041篇
  1967年   8388篇
  1966年   7825篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Syphilis can be spread during the practice of dentistry by direct contact with mucosal lesions of primary and secondary syphilis or blood and saliva from infected patients. The dentist also can play an important role in the control of syphilis by identification of the signs and symptoms of syphilis, patient education, and referral. The incidence of syphilis and the impact of control measures are presented with the emphasis on the past 5 years. The signs and symptoms of primary, secondary, latent, and late (tertiary) syphilis are reviewed. Current medical treatment is presented. The oral manifestations of syphilis are discussed as well as the dental management of the infected patient.  相似文献   
994.
A 53-year-old male with hepatitis C cirrhosis, who had been refused liver transplantation because of hypertrophic cardiomyopathy (HC), underwent nonsurgical septal ablation using alcohol with resolution of his ventricular outflow obstruction. This patient was able to subsequently undergo a successful deceased donor liver transplantation. This is the first reported case of alcohol induced septal ablation being performed in a cirrhotic patient with HC. Such nonsurgical procedures may be attractive in cirrhotic patients who are refused access to liver transplantation because of high surgical risk.  相似文献   
995.
996.
Although extensively studied, the pathophysiologic characteristics of chronic cyclosporine (CsA) nephrotoxicity are still far from being completely understood. The recognition of chronic CsA nephrotoxicity in allografted kidneys is hampered by a lack of easily assessable sensitive and specific markers. Long-term results of CsA withdrawal trials and trials that evaluated CsA sparing or withdrawal after the diagnosis of chronic allograft nephropathy (CAN) have shown that chronic CsA nephrotoxicity has a more important role in the etiology of late transplant dysfunction than appreciated before. Various hypotheses have explained the renal structural changes of chronic CsA nephrotoxicity including ischemia, cellular toxicity, and the stimulation of renal fibrosis by growth factors or cytokines. Possible ways to prevent chronic CsA nephrotoxicity include improved therapeutic drug monitoring and CsA withdrawal or avoidance. Patients with aspecific CAN in late biopsy may benefit from withdrawal of CsA or a reduction of its dose. Current knowledge is being discussed. It is concluded that in the near future more strategies are likely to be used to prevent loss of allograft function as a result of drug toxicity.  相似文献   
997.
Purpose. In the National Heart, Lung, and Blood Institute Guidelines for the Diagnosis and Management of Asthma, the expert panel recommends that a written asthma action plan be provided for all patients with asthma. Studies evaluating the usefulness of the asthma action plan in children are limited. We aim to determine exacerbation frequency and usefulness of the asthma action plan in managing exacerbations that occur in a pediatric primary care setting. Methods. Caretakers of asthmatic children attending the general pediatric clinic in an inner-city hospital completed a one-page questionnaire covering topics such as asthma severity, frequency of exacerbations, and possession/usefulness of an asthma action plan. Although controversy exists over the definition of yellow and red zone exacerbations, we defined the yellow zone as symptoms that require albuterol more than three times a day or more than two nights in succession. The red zone was defined as symptoms requiring systemic corticosteroids and/or an urgent physician visit. Results. Seventy of 75 subjects completed the survey. Almost 80% of respondents carried the diagnosis of persistent asthma, whereas the remainder had intermittent asthma. Exacerbation frequency over a 3-month period was determined. Approximately 80% of children experienced at least one yellow zone episode: 42% had one or two yellow zone episodes, and 39.6% had between three and five episodes. Sixty-three percent of patients did not experience a single red zone exacerbation. Almost 75% (44 of 59) of subjects possessed an asthma action plan. Ninety percent (37 of 41) of respondents with action plans found the plan to be useful in managing exacerbations. Conclusion. Approximately four of every five asthmatic children seen in this primary care setting experienced a yellow zone exacerbation at least once during a 3-month period. One third experienced at least one red zone episode. Nine of every 10 caretakers with an action plan reported the asthma action plan to be of value in managing exacerbations.  相似文献   
998.
A randomized, placebo-controlled, double-blind study involving 60 subjects, aged 6-18 years old, was conducted over a period of 3 months to determine the effect of Pycnogenol® (a proprietary mixture of water-soluble bioflavonoids extracted from French maritime pine) on mild-to-moderate asthma. After baseline evaluation, subjects were randomized into two groups to receive either Pycnogenol® or placebo. Subjects were instructed to record their peak expiratory flow with an Assess® Peak Flow Meter each evening. At the same time, symptoms, daily use of rescue inhalers (albuterol), and any changes in oral medications were also recorded. Urine samples were obtained from the subjects at the end of the run-in period, and at 1-, 2-, and 3-month visits. Urinary leukotriene C4/D4/E4 was measured by an enzyme immunoassay. Compared with subjects taking placebo, the group who took Pycnogenol® had significantly more improvement in pulmonary functions and asthma symptoms. The Pycnogenol® group was able to reduce or discontinue their use of rescue inhalers more often than the placebo group. There was also a significant reduction of urinary leukotrienes in the Pycnogenol® group. The results of this study demonstrate the efficacy of Pycnogenol® as an adjunct in the management of mild-to-moderate childhood asthma.  相似文献   
999.
AIMS: To determine the most appropriate regression models to use when assessing risk factors for severe hypoglycaemia and to investigate the impact of model misspecification and its clinical implications. METHODS: A total of 1229 children with Type 1 diabetes (mean age 11.7 years sd 4.1), of which 605 (49.2%) were males, were studied. Prospective assessment of severe hypoglycaemia (an event leading to loss of consciousness or seizure) was made over the 9-year period, 1992-2001. Patients were seen every 3 months and episodes of hypoglycaemia along with clinical data were recorded. Over 70% of children never experienced a severe hypoglycaemic event. Data were analysed using the Poisson regression, negative binomial, zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) models. The over-dispersion and likelihood ratio statistics were calculated and the analytical methods compared. RESULTS: The Poisson regression model did not fit the data well. The negative binomial and the zero inflated Poisson and negative binomial models fitted the data better than Poisson. CONCLUSIONS: The commonly used Poisson regression models to analyse hypoglycaemia epidemiology may lead to biased parameter estimates and incorrect determination of risk factors for hypoglycaemia. We recommend the use of the negative binomial or zero inflated models to examine any risk factors associated with severe hypoglycaemia. Careful consideration must be given to the interpretation of hypoglycaemia surveys and their analysis.  相似文献   
1000.
Exhaled breath condensate (EBC) provides a noninvasive means of sampling the lower respiratory tract. Collection of EBC might be useful in the assessment of airway oxidative stress in smokers. The aim of this study was to determine 8-isoprostane and hydrogen peroxide levels in EBC, and, in addition, to investigate the reproducibility of these measurements. EBC samples were collected from 12 healthy male smokers at three time points within 1 week. 8-isoprostane and H2O2 were measured in nonconcentrated EBC using immunochemical and colorimetric assays, respectively. 8-isoprostane and H2O2 were detected in only 36 and 47% of all EBC samples, respectively. It was not possible to calculate the within-subject variation in a reliable manner since only three of the 12 smokers exhibited detectable 8-isoprostane concentrations on all three occasions (mean 4.6 pg x mL(-1); range 3.9-7.7 pg x mL(-1)), whereas H2O2 could not be detected on all three occasions in any of the smokers. Spiking experiments revealed a recovery of 83.5-109.5% for 8-isoprostane and 69.9-129.0%, for H2O2 in fresh EBC samples. It was concluded that levels of 8-isoprostane and hydrogen peroxide cannot be reproducibly assessed in exhaled breath condensate from healthy smokers because of their low concentration and/or the lack of sensitivity of the available assays.  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