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   1783859篇
  免费   123466篇
  国内免费   2575篇
耳鼻咽喉   25430篇
儿科学   54414篇
妇产科学   46971篇
基础医学   256105篇
口腔科学   51708篇
临床医学   158689篇
内科学   338885篇
皮肤病学   39090篇
神经病学   137271篇
特种医学   69646篇
外国民族医学   276篇
外科学   275914篇
综合类   36609篇
现状与发展   2篇
一般理论   476篇
预防医学   125373篇
眼科学   42060篇
药学   140996篇
  10篇
中国医学   4421篇
肿瘤学   105554篇
  2018年   18272篇
  2017年   14288篇
  2016年   16162篇
  2015年   18148篇
  2014年   24674篇
  2013年   36197篇
  2012年   49765篇
  2011年   52439篇
  2010年   30889篇
  2009年   29242篇
  2008年   49531篇
  2007年   52498篇
  2006年   53496篇
  2005年   51176篇
  2004年   49220篇
  2003年   47201篇
  2002年   45713篇
  2001年   96962篇
  2000年   99762篇
  1999年   82968篇
  1998年   20625篇
  1997年   18191篇
  1996年   18212篇
  1995年   17139篇
  1994年   15692篇
  1993年   14703篇
  1992年   62865篇
  1991年   60557篇
  1990年   59065篇
  1989年   56913篇
  1988年   51862篇
  1987年   50451篇
  1986年   47328篇
  1985年   45129篇
  1984年   32693篇
  1983年   27568篇
  1982年   14977篇
  1981年   13101篇
  1979年   29455篇
  1978年   19974篇
  1977年   17477篇
  1976年   15314篇
  1975年   17192篇
  1974年   20301篇
  1973年   19501篇
  1972年   18588篇
  1971年   17460篇
  1970年   16328篇
  1969年   15465篇
  1968年   13992篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
35.
36.
37.
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   
38.
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   
39.
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   
40.
Background Familial partial lipodystrophy (FPLD) is a monogenic form of diabetes characterised by a dominantly inherited disorder of adipose tissue associated with the loss of subcutaneous fat from the limbs and trunk, with excess fat deposited around the face and neck. The lipodystrophy causes severe insulin resistance, resulting in acanthosis nigricans, diabetes, dyslipidaemia, and increased risk of cardiovascular disease. Preliminary results from animals and man suggest that increasing subcutaneous fat by treatment with thiazolidinediones should improve insulin resistance and the associated features of this syndrome. Case report We report a 24-year-old patient with FPLD caused by a mutation in the LMNA gene (R482W) treated with 12 months of rosiglitazone. Subcutaneous fat increased following rosiglitazone treatment as demonstrated by a 29% generalised increase in skin-fold thickness. Leptin levels increased from 5.8 to 11.2 ng/ml. Compared with treatment on Metformin, there was an increase in insulin sensitivity (HOMA S% 17.2–31.6) but no change in glycaemic control. The lipid profile worsened during the follow-up period. Conclusion This initial case suggests that, for modification of cardiovascular risk factors, there are no clear advantages in treating patients with FPLD with rosiglitazone despite increases in subcutaneous adipose tissue. Larger series will be needed to identify moderate beneficial effects and treatment may be more effective in patients with generalised forms of lipodystrophy.  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