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   11984篇
  免费   996篇
  国内免费   22篇
耳鼻咽喉   105篇
儿科学   504篇
妇产科学   385篇
基础医学   1858篇
口腔科学   340篇
临床医学   1229篇
内科学   2475篇
皮肤病学   124篇
神经病学   1292篇
特种医学   550篇
外科学   1223篇
综合类   155篇
一般理论   7篇
预防医学   1091篇
眼科学   193篇
药学   808篇
中国医学   17篇
肿瘤学   646篇
  2022年   98篇
  2021年   157篇
  2020年   121篇
  2019年   186篇
  2018年   215篇
  2017年   191篇
  2016年   211篇
  2015年   220篇
  2014年   275篇
  2013年   438篇
  2012年   595篇
  2011年   692篇
  2010年   350篇
  2009年   343篇
  2008年   576篇
  2007年   523篇
  2006年   530篇
  2005年   513篇
  2004年   489篇
  2003年   446篇
  2002年   409篇
  2001年   426篇
  2000年   407篇
  1999年   393篇
  1998年   170篇
  1997年   149篇
  1996年   127篇
  1995年   133篇
  1994年   144篇
  1993年   118篇
  1992年   266篇
  1991年   278篇
  1990年   224篇
  1989年   237篇
  1988年   226篇
  1987年   181篇
  1986年   168篇
  1985年   155篇
  1984年   139篇
  1983年   115篇
  1982年   66篇
  1981年   81篇
  1979年   89篇
  1978年   73篇
  1977年   85篇
  1976年   64篇
  1975年   80篇
  1974年   91篇
  1973年   61篇
  1971年   71篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The anterior, posterior, and transverse bundles of the medial collateral ligaments of fresh cadaveric elbows were painted with a special radiopaque tantalum cyanoacrylic preparation. The extent of each ligament and their origins and insertions were examined with radiography. This study provided radiographic correlation for these important soft tissue structures and an anatomic understanding of elbow fractures with ligament avulsion.  相似文献   
22.
In a retrospective study, which comprised the whole Dutch childhood population of approximately 3 million children, the authors assessed the influence of an isolated meningeal relapse, occurring as first relapse, together with some patient and treatment characteristics on prognosis in 142 children with acute lymphoblastic leukemia (ALL). Until their first relapse, patients were initially treated according to standard protocols, whereas the treatment for relapse was heterogeneous. Concerning the probability of achieving a second complete remission (CR) it appears that the duration of the first CR is the single most important prognostic factor. The duration of the first CR is also the most important factor with regard to the duration of the second CR, upon which also age and sex have a significant influence. Concerning the survival from the time of central nervous system (CNS) relapse, again the duration of the first CR appears to be the most important prognostic factor, followed by age and the institution of systemic reinduction treatment. Other factors, such as initial leukocyte count, attainment of first CR within 48 days, type of reinduction treatment, and the cerebral spinal fluid (CSF) blast count at the time of relapse, have a less important, but nevertheless significant influence on survival. The median survival from the time of CNS relapse is 25 months, the 5-year survival is 25%, whereas the ultimate survival will be less than 20%. From 90 patients who developed second or subsequent relapses, 75% experienced a bone marrow relapse during the follow-up period. From this study the authors conclude that CNS relapse in children with ALL carries a grave prognosis, which requires the institution of intensive retreatment programs.  相似文献   
23.
经盲肠造口顺行性结肠灌洗术可作为重度排便障碍患儿的一种治疗选择。该研究目的是报道31例有功能性便秘(n=9)、Hirschsprung病(n=2)、肛门闭锁(n=5)、脊柱异常(n=8)、肛门闭锁合并脊髓栓系综合征(n=7)患儿行盲肠造口术的4年临床经验。回顾性收集包括并发症、顺行性结肠灌洗术的应用、症状与生活质量等各方面资料。31例患儿中有30例成功地安置了盲肠造口导管。功能性便秘(P=0.01)、肛门闭锁(P〈0.01)及脊髓异常(P=0.04)患儿便秘的发生率明显降低。功能性便秘及肛门闭锁患儿的生活质量有所提高。经皮及外科置管的并发症无显性差异。对于各种原因造成排便障碍的患儿,通过盲肠造口的顺行性结肠灌洗术可使患儿的症状与生活质量得到明显改善。  相似文献   
24.
25.
A review of the literature shows adenocarcinoma of the anal canal to have a poor outcome. Radical surgery is the treatment of choice for this disease.  相似文献   
26.
We evaluated the sensitivity and specificity of positron emission tomography for diagnosis of probable Alzheimer's disease under conditions similar to those encountered in the routine clinical practice of nuclear medicine. We obtained tomographic images of regional cerebral blood flow from three groups of subjects: (1) 13 subjects, ages 69 to 84, who had probable Alzheimer's disease diagnosed by validated clinical criteria; (2) 15 subjects, ages 57 to 77, who had Parkinson's disease without dementia; and (3) 11 subjects, ages 65 to 83, who were normal. Three blinded reviewers, who had not previously seen the images, categorized them as normal, bilateral temporoparietal flow defects typical of Alzheimer's disease, or other abnormality. Consensus interpretation demonstrated sensitivity of 0.38 (5/13) and specificity of 0.88 (23/26) for identifying patients with probable Alzheimer's disease. Thus, the criterion of bilateral temporoparietal reduction in cerebral blood flow used in this study did not have sufficient sensitivity to be of clinical value. While other criteria may be developed to improve diagnostic accuracy, clinical utility can be established only by testing for validity in patients with a full spectrum of complicating neurologic and psychiatric conditions for whom diagnosis is uncertain and who are then followed longitudinally to determine clinical outcome or pathologic findings.  相似文献   
27.
OBJECTIVE: Multi-vessel Doppler ultrasonography and biophysical profile scoring (BPS) are used in the surveillance of growth restricted fetuses (IUGR). The interpretation of both tests performed concurrently may be complex. This study examines the relationship between Doppler ultrasonography and biophysical test results in IUGR fetuses. METHODS: Three hundred and twenty-eight IUGR fetuses (abdominal circumference < 5th percentile, elevated umbilical artery (UA) pulsatility index (PI)) had concurrent surveillance with UA, middle cerebral artery (MCA) and ductus venosus (DV) Doppler ultrasonography and BPS (fetal tone, movement, breathing, maximal amniotic fluid pocket and fetal heart rate). Patients were stratified into three groups according to their Doppler examination: (1) abnormal UA alone; (2) brain sparing (MCA-PI > 2 SD below mean for gestational age); and (3) abnormal DV (PI > 2 SD above the mean for gestational age) and BPS groups: (1) normal (> 6/10); (2) equivocal (6/10); and (3) abnormal (< 6/10). Predictions of short-term perinatal outcomes by both modalities were compared for stratification. The distribution and concordance of Doppler and BPS test results were examined for the whole patient group and based on delivery prior to 32 weeks' gestation. RESULTS: Abnormal UA Doppler results alone were observed in 109 fetuses (33.2%), brain sparing in 87 (26.5%) and an abnormal DV in 132 (40.2%). The BPS was normal in 158 (48.2%), equivocal in 68 (20.7%) and abnormal in 102 (31.1%). Both testing modalities stratified patients into groups with comparable acid-base disturbance and perinatal outcome. Of the nine possible test combinations the largest subgroups were: abnormal UA alone/normal BPS (n = 69; 21%) and abnormal DV Doppler/abnormal BPS (n = 62; 18.9%). Assessment of compromise by both testing modalities was concordant in 146 (44.5%) cases. In 182 fetuses with discordant results the BPS grade was better in 115 (63.2%, P < 0.0001). Marked disagreement of test abnormality was present in 57 (17.4%) fetuses. Of these, abnormal venous Doppler in the presence of a normal BPS constituted the largest group (Chi-square P < 0.002). Stratification was not significantly different in patients delivered prior to 32 weeks' gestation. CONCLUSION: Doppler ultrasonography and BPS effectively stratify IUGR fetuses into risk categories, but Doppler and BPS results do not show a consistent relationship with each other. Since fetal deterioration appears to be independently reflected in these two testing modalities further research is warranted to investigate how they are best combined.  相似文献   
28.
Finding the gene(s) for alcoholism   总被引:1,自引:0,他引:1  
E Gordis  B Tabakoff  D Goldman  K Berg 《JAMA》1990,263(15):2094-2095
  相似文献   
29.
30.
Modified ultrafiltration after cardiopulmonary bypass in children has been shown to be associated with an increase in arterial blood pressure. As part of a series of studies to investigate the possible causes of this blood pressure elevation, the hypothesis that if filtration was removing a significant amount of fentanyl, then the increase in blood pressure might be due to pain was proposed. Ten children, aged between 0.5 and 9.3 years (median 3.8 years), weighing 5.9 to 25..5 kg (median 15.7 kg), underwent corrective cardiac surgery (incorporating modified ultrafiltration). A standard anesthetic protocol was followed, with up to 78 μg/kg of fentanyl given prebypass for analgesia. After completion of cardiopulmonary bypass, modified ultrafiltration was commenced at 100 mL/min until a hematocrit of 35% was reached. Samples were taken of arterial blood (prefiltration, 3, 10, and 20 minutes postfiltration), the venous reservoir blood (prefiltration) and the filtrate (5 and 10 minutes into filtration). Hemodynamic data were recorded both prefiltration and postfiltration. The hemodynamic data showed the expected rise in both systemic arterial pressure and cardiac index after ultrafiltration. The plasma fentanyl concentrations did not significantly change after ultrafiltration: 1.59 to 12.39 ng/mL (median 6.27 ng/mL) prefiltration and 2.05 to 15.59 ng/mL (6.29 ng/mL) at 3 minutes, 2.22 to 12.64 ng/mL (6.87 ng/mL) at 10 minutes, and 1.83 to 11.52 ng/mL (5.85 ng/mL) at 20 minutes postfiltration. The concentration of fentanyl in the venous reservoir, 2.06 to 11.64 ng/mL (7.04 ng/mL), was not significantly different from the plasma levels. The level of fentanyl in the filtrate was significantly less than the plasma levels, 0.243 to 1.87 ng/mL (0.894 ng/mL) at 5 minutes and 0.385 to 1.688 ng / mL (0.952 ng / mL) at 10 minutes into filtration; (P < 0.02 by the Wilcoxon signed-rank method). The data show that the plasma fentanyl concentration was not significantly reduced by modified ultrafiltration. The fentanyl levels found prefiltration were maintained postfiltration, and the observed changes in systemic arterial pressure were not due to an acute fall in the plasma concentration of analgesic drug.  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