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   2676418篇
  免费   201616篇
  国内免费   6351篇
耳鼻咽喉   35502篇
儿科学   88846篇
妇产科学   74280篇
基础医学   384296篇
口腔科学   75430篇
临床医学   246471篇
内科学   515952篇
皮肤病学   54620篇
神经病学   221033篇
特种医学   102753篇
外国民族医学   804篇
外科学   391474篇
综合类   63108篇
现状与发展   4篇
一般理论   963篇
预防医学   219475篇
眼科学   59874篇
药学   198564篇
  9篇
中国医学   5432篇
肿瘤学   145495篇
  2018年   35895篇
  2017年   27932篇
  2016年   31543篇
  2015年   26996篇
  2014年   37035篇
  2013年   57056篇
  2012年   79770篇
  2011年   89705篇
  2010年   54403篇
  2009年   49723篇
  2008年   84694篇
  2007年   90876篇
  2006年   81775篇
  2005年   80862篇
  2004年   78797篇
  2003年   76247篇
  2002年   73663篇
  2001年   117283篇
  2000年   121345篇
  1999年   102270篇
  1998年   29030篇
  1997年   26461篇
  1996年   26088篇
  1995年   25224篇
  1994年   23729篇
  1993年   22404篇
  1992年   83547篇
  1991年   81764篇
  1990年   79574篇
  1989年   76403篇
  1988年   71078篇
  1987年   69761篇
  1986年   66513篇
  1985年   64059篇
  1984年   48174篇
  1983年   41386篇
  1982年   24780篇
  1981年   22012篇
  1979年   45239篇
  1978年   31796篇
  1977年   26574篇
  1976年   25424篇
  1975年   26582篇
  1974年   32509篇
  1973年   31470篇
  1972年   28943篇
  1971年   27173篇
  1970年   25081篇
  1969年   23305篇
  1968年   21789篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
In cystic fibrosis (CF), perturbations of total daily energy expenditure (TDEE) may be a major determinant of altered nutrition and growth. Measurement of TDEE is problematic, though the flex-heart rate method (FHRM) provides a close estimation of TDEE, as compared to the cost-prohibitive, gold standard, the double-labeled water method, and permits estimates of the energy cost of daily activities (ECA) above resting energy expenditure (REE). We hypothesize that alterations in ECA affects TDEE in CF. PURPOSE: To measure components of TDEE in adolescents with CF and normal lung function compared with controls, and to determine whether ECA can be improved by diet and exercise. METHODS: Clinically stable CF subjects (aged 9-13, n=12) and age- and gender-matched controls (n=13) had repeated measurements of TDEE by FHRM, REE, and maximal cardiopulmonary exercise testing (CPET) during a 6-week exercise and diet program. RESULTS: While the mean REE was similar in both groups, ECA was significantly lower in CF adolescents as compared to controls (p=0.02). During CPET, maximal exercise in CF was characterized by hyperventilation, which was unrelated to ventilation-perfusion mismatching. There were no changes in REE after dietary intervention. CONCLUSION: ECA in CF adolescents with normal lung function is lower when compared to healthy controls. These findings support the hypothesis that clinically stable patients with CF have inefficient energy metabolism or alternatively conserve energy during activities of daily living.  相似文献   
62.
63.
64.
OBJECTIVES: To evaluate a novel method for localization of subdural electrodes in presurgical assessment of patients with drug-resistant focal epilepsy. METHODS: We studied eight consecutive patients with posterior epilepsy in whom subdural electrodes were implanted for presurgical evaluation. Electrodes were detected on post-implantation brain CT scans through a semiautomated procedure based on a MATLAB routine. Then, post-implantation CT scans were fused with pre-implantation MRI to localize the electrodes in relation to the underlying cortical structures. The reliability of this procedure was tested by comparing 3D-rendered MR images of the electrodes with electrode position as determined by intraoperative digital photography. RESULTS: In each patient, all electrodes could be correctly localized and visualized in a stereotactic space, thus allowing optimal surgery planning. The agreement between the procedure-generated images and the digital photographs was good according to two independent raters. The mean mismatch between the 3D images and the photographs was 2 mm. CONCLUSIONS: While our findings need confirmation on larger samples including patients with anterior epilepsy, this procedure allowed to localize subdural electrodes and to establish the spatial relationship of each electrode to the underlying brain structure, either normal or damaged, on brain convessity, basal and medial cortex. SIGNIFICANCE: Being simple, rapid, unexpensive, and reliable, this procedure holds promise to be useful to optimize epilepsy surgery planning.  相似文献   
65.
Abstract Guillain-Barré syndrome (GBS) is a disease of the peripheral nervous system, which is caused by aberrant immune responses directed against some components of peripheral nerves. GBS is rarely accompanied by cardiovascular involvement. We describe a case of acute neuropathy complicated by sudden heart failure and left ventricular dysfunction which had a presumably neurogenic origin. Pathogenesis of acute heart failure is probably due to transitorial stunned myocardium and neurogenic cardiac injury. We show a rare case of transitorial and acute cardiac dysfunction by echocardiography and laboratory markers of heart failure.  相似文献   
66.
A 27-year-old man was admitted with high fever and shivers eleven days after returning from vacation in Indonesia. Physical examination, laboratory values, abdominal ultrasound, and chest x-ray were not conclusive. All blood cultures yielded growth of Salmonella enterica serovar Typhi, and typhoid fever was diagnosed. Subsequently, the patient developed septic shock and pulmonary edema.In this case report epidemiological, clinical, and therapeutic aspects of typhoid fever are discussed with special emphasis on criteria for severe typhoid fever, which is treated with additional glucocorticoids.  相似文献   
67.
68.
The numbers of free flap donor site as well as their indications are constantly increasing. Despite increasing popularity of microvascular reconstructive procedures, literature lacks clear and objective outcome criteria. This paper reports on a simple outcome classification that has become a routine part of the unit's large workload of microvascular outcome recording. The classification was formed through a retrospective analysis of 241 consecutive cases from 2000 to 2001 and is a five graded numerical classification. Grade 1 equates to total success without co-morbidity and grade 5 to a major complication such as amputation, etc., whatever the status of the flap itself. From 2002 to 2005 the classification was prospectively used on 527 consecutive cases with ease of integration into routine clinical practice. The Classification would enable a more objective record keeping thus analysis of the outcome. It would allow a more realistic comparison of different techniques or donor types as well set a benchmarking level for further improvement of the results.  相似文献   
69.
Here we report how the different types of regional muscle involvement, i.e. bulbar, ocular or generalized, in patients with myasthenia gravis (MG) influence the mental aspects of quality of life. Clinical examination according to Osserman was performed in 48 MG patients (45 women, three men; mean age 54, SD 12 years). Each patient was at the time for clinical evaluation asked to fill out the disease-specific Myasthenia Gravis Questionnaire (MGQ) and the Short-Form 36-item questionnaire for health survey (SF-36) as patient-oriented tools. We related the regional domains (generalized domain, bulbar domain and ocular domain) of the MGQ and the clinical findings, respectively, with mental quality of life as assessed by SF-36. Bulbar and generalized involvement results in impairment of mental aspects of quality of life, whereas ocular involvement does not.  相似文献   
70.
Summary Of the 105 great cormorants (Phalacrocorax carbo sinensins) from northern Poland (the Vistula Lagoon and Masurian Lake District), examined in 2000–2001, 67 proved hosts of the nematode Syncuaria squamata (Linstow, 1883). The prevalence, mean intensity, and intensity range amounted to 63.8 %, 36.2 specimens, and 1–120 specimens, respectively. The infection was heavier in the immature birds (84.6 %, 40.9 inds, and 1–120 inds) than in the adults (3.7 %, 1 ind.). The nematodes were dominated by gravid females (n=1846), followed by males (n=157), immature females (n=79), and L4 larvae (n=2). Measurements of the parasite are provided. S. squamata is a new species for the parasite fauna of Poland.  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