首页 | 官方网站   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   25302篇
  免费   1588篇
  国内免费   129篇
医药卫生   27019篇
  2023年   244篇
  2022年   265篇
  2021年   999篇
  2020年   647篇
  2019年   813篇
  2018年   1020篇
  2017年   715篇
  2016年   791篇
  2015年   873篇
  2014年   1179篇
  2013年   1414篇
  2012年   2051篇
  2011年   2312篇
  2010年   1188篇
  2009年   948篇
  2008年   1569篇
  2007年   1534篇
  2006年   1283篇
  2005年   1197篇
  2004年   949篇
  2003年   881篇
  2002年   720篇
  2001年   496篇
  2000年   456篇
  1999年   419篇
  1998年   156篇
  1997年   114篇
  1996年   83篇
  1995年   64篇
  1994年   65篇
  1993年   57篇
  1992年   191篇
  1991年   155篇
  1990年   125篇
  1989年   117篇
  1988年   109篇
  1987年   66篇
  1986年   86篇
  1985年   71篇
  1984年   62篇
  1983年   47篇
  1982年   36篇
  1980年   33篇
  1979年   55篇
  1978年   26篇
  1977年   27篇
  1976年   34篇
  1974年   26篇
  1971年   29篇
  1969年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish‐eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH‐induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus‐2 (CPV‐2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH‐induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV‐2.  相似文献   
3.
4.
5.
6.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic.  相似文献   
7.
8.
9.
Background and aimsThe long-term relations between excessive adiposity in early childhood and unfavourable cardiometabolic profiles in later ages are not yet completely understood. We aimed to assess the associations between birth weight (BW) and BMI from 6 months to 6 years of age, with biomarkers indicative of low-grade inflammation, insulin resistance and lipid profiles in adolescence.Methods and resultsRetrospective school-based study with 415 Portuguese adolescents (220 girls), mean age of 14.08 ± 1.6 years old. Anthropometric data from birth to 6 years old was extracted from individual child health book records. Actual weight and height were measured and BMI calculated. Participants were classified at each time point as normal weight or overweight according to WHO reference values. Biomarkers were obtained from venous blood samples. Linear regressions were used to explore the associations between the biomarkers and early life anthropometric indicators. From 2 years onwards, BMI associated positively with the inflammatory score and HOMA-IR in adolescence. Children who were overweight/obese from 2 to 6 years of age presented significantly higher inflammatory score and HOMA-IR later in adolescence. TC/HDL ratio was also positively associated with BMI from the age of 5 years onwards. The associations between BMI and cardiometabolic outcomes remained positive in adolescence, with overweight adolescents presenting a higher inflammatory score, HOMA-IR and TC/HDL than normal weight adolescents.ConclusionA high BMI from an early age was consistently associated with worse inflammatory and lipid profiles and insulin resistance in adolescence. No associations were found between BW and the same studied outcomes.  相似文献   
10.
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-23

京公网安备 11010802026262号