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   1077284篇
  免费   71932篇
  国内免费   1373篇
耳鼻咽喉   15076篇
儿科学   34658篇
妇产科学   28686篇
基础医学   153760篇
口腔科学   29593篇
临床医学   95161篇
内科学   204063篇
皮肤病学   24446篇
神经病学   81645篇
特种医学   43066篇
外国民族医学   201篇
外科学   163599篇
综合类   21713篇
现状与发展   1篇
一般理论   263篇
预防医学   74749篇
眼科学   24600篇
药学   86263篇
  7篇
中国医学   2805篇
肿瘤学   66234篇
  2019年   7791篇
  2018年   11355篇
  2017年   8943篇
  2016年   10151篇
  2015年   11331篇
  2014年   15352篇
  2013年   22300篇
  2012年   30689篇
  2011年   32455篇
  2010年   19053篇
  2009年   17912篇
  2008年   30061篇
  2007年   32178篇
  2006年   32833篇
  2005年   31154篇
  2004年   29814篇
  2003年   28653篇
  2002年   27609篇
  2001年   60068篇
  2000年   61555篇
  1999年   50995篇
  1998年   12484篇
  1997年   11012篇
  1996年   11036篇
  1995年   10330篇
  1994年   9356篇
  1993年   8873篇
  1992年   37818篇
  1991年   36300篇
  1990年   35779篇
  1989年   34308篇
  1988年   30891篇
  1987年   30009篇
  1986年   28241篇
  1985年   26468篇
  1984年   19203篇
  1983年   16129篇
  1982年   8842篇
  1979年   17045篇
  1978年   11420篇
  1977年   10245篇
  1976年   8847篇
  1975年   10082篇
  1974年   11666篇
  1973年   11293篇
  1972年   10769篇
  1971年   10106篇
  1970年   9266篇
  1969年   8951篇
  1968年   7933篇
排序方式: 共有10000条查询结果,搜索用时 284 毫秒
21.
22.
23.
24.
25.
26.
27.
OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.  相似文献   
28.
We report the case of a 38-year-old woman who presented with chronic lower abdominal pain. Her past medical history included a splenectomy due to abdominal trauma. Ultrasound examination revealed four pelvic tumors which, upon laparotomy, were found to be the result of splenosis. Approximately 100 cases of splenosis have been reported but only a minority of them have been published in the gynecological literature. Our case indicates that those involved in pelvic scanning (even of asymptomatic women) and/or treating those complaining of lower abdominal pain or presenting with pelvic tumors should be aware of splenosis as a possible diagnosis.  相似文献   
29.
Although surgical lung resection could improve prognosis in some patients with multidrug-resistant tuberculosis (MDR-TB), there are no reports on the optimal candidates for this surgery. The aim of the present study was to elucidate the prognostic factors for surgery in patients with MDR-TB. Patients who underwent lung resection for the treatment of MDR-TB between March 1993 and December 2004 were included in the present study. Treatment failure was defined as greater than or equal to two of the five cultures recorded in the final 12 months of treatment being positive, any one of the final three cultures being positive, or the patient having died during treatment. The variables that affected treatment outcomes were identified through univariate and multivariate logistic regression analysis. In total, 79 patients with MDR-TB were included in the present study. The treatment outcomes of 22 (27.8%) patients were classified as failure. A body mass index <18.5 kg x m(-2), primary resistance, resistance to ofloxacin and the presence of a cavitary lesion beyond the range of the surgical resection were associated with treatment failure. Low body mass index, primary resistance, resistance to ofloxacin and cavitary lesions beyond the range of resection are possible poor prognostic factors for surgical lung resection in multidrug-resistant tuberculosis patients.  相似文献   
30.
The clinical outcome and appropriate management for patients showing 'borderline changes' on allograft biopsy after renal transplantation is still controversial. In an attempt to identify predictive factors of clinical outcome of patients with such lesions, we reviewed the clinical course of 91 patients with borderline changes. Multivariate analysis revealed significant and independent effects of histological stage (i + t < or = or > 2) and time to borderline changes (< or = or > 3 months after transplant) on serum creatinine levels at 1 year from borderline changes episodes (respectively, p = 0.04 and p = 0.02) and only a significant effect of time to borderline changes on serum creatinine levels at 2 years (p = 0.005). Renal function at 1 year and 2 years as 5- and 8-year graft survival were not significantly different in the group of patients treated with antirejection therapy (T group, n = 49) compared with the untreated group (UT group, n = 42). This study strongly suggests that borderline changes with histological score (i + t) > 2 and late episodes of borderline changes should be considered to be of poor prognosis.  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