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   12101篇
  免费   1007篇
  国内免费   13篇
耳鼻咽喉   106篇
儿科学   495篇
妇产科学   385篇
基础医学   1873篇
口腔科学   342篇
临床医学   1218篇
内科学   2507篇
皮肤病学   134篇
神经病学   1292篇
特种医学   598篇
外科学   1227篇
综合类   171篇
一般理论   7篇
预防医学   1099篇
眼科学   192篇
药学   812篇
中国医学   17篇
肿瘤学   646篇
  2022年   98篇
  2021年   156篇
  2020年   120篇
  2019年   185篇
  2018年   218篇
  2017年   194篇
  2016年   214篇
  2015年   219篇
  2014年   276篇
  2013年   443篇
  2012年   597篇
  2011年   695篇
  2010年   348篇
  2009年   345篇
  2008年   583篇
  2007年   522篇
  2006年   534篇
  2005年   519篇
  2004年   490篇
  2003年   448篇
  2002年   413篇
  2001年   423篇
  2000年   406篇
  1999年   394篇
  1998年   177篇
  1997年   162篇
  1996年   130篇
  1995年   139篇
  1994年   143篇
  1993年   121篇
  1992年   265篇
  1991年   277篇
  1990年   225篇
  1989年   240篇
  1988年   229篇
  1987年   184篇
  1986年   172篇
  1985年   171篇
  1984年   145篇
  1983年   117篇
  1982年   70篇
  1981年   88篇
  1979年   90篇
  1978年   75篇
  1977年   84篇
  1976年   64篇
  1975年   82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.
24.
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   
25.
26.
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   
27.
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   
28.
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   
29.
Experiments were performed to determine whether bacterial translocation (BT) after hemorrhagic shock is due to a reperfusion injury mediated by xanthine oxidase-derived oxidants. Rats were subjected to 30 minutes of shock (30 mm Hg) followed by reinfusion of shed blood. Twenty-four hours after hemorrhage and reinfusion, the mesenteric lymph node, liver, and spleen were harvested from each animal for bacterial culture, and the ileum and cecum were examined histologically. Sham-shocked (control) rats were instrumented, but blood was not withdrawn. The incidence of BT was higher in the shocked rats (61%) than in the sham-shocked animals (7%) (p less than 0.01). Allopurinol (50 mg/kg, administered orally), a competitive inhibitor of xanthine oxidase, reduced the incidence of shock-induced BT to 14% (p = 0.02). Similarly, rats fed a tungsten-supplemented molybdenum-free diet, which inactivates xanthine oxidase, reduced shock-induced BT to 10% (p = 0.02). The histologic damage cause by hemorrhagic shock was prevented by blocking xanthine oxidase activity. Thus hemorrhagic shock-induced bacterial translocation from the gut appears to be mediated by oxidants generated by activation of the xanthine oxidase system.  相似文献   
30.
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   
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