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   137443篇
  免费   7308篇
  国内免费   222篇
耳鼻咽喉   2057篇
儿科学   5752篇
妇产科学   4553篇
基础医学   19531篇
口腔科学   3141篇
临床医学   10369篇
内科学   26023篇
皮肤病学   3902篇
神经病学   11174篇
特种医学   6141篇
外国民族医学   40篇
外科学   21998篇
综合类   1762篇
一般理论   40篇
预防医学   7266篇
眼科学   3895篇
药学   9516篇
中国医学   380篇
肿瘤学   7433篇
  2019年   917篇
  2018年   1267篇
  2017年   1075篇
  2016年   1504篇
  2015年   1632篇
  2014年   2106篇
  2013年   2970篇
  2012年   4093篇
  2011年   4204篇
  2010年   2533篇
  2009年   2465篇
  2008年   4100篇
  2007年   4423篇
  2006年   4586篇
  2005年   4665篇
  2004年   4538篇
  2003年   4347篇
  2002年   4280篇
  2001年   7708篇
  2000年   7581篇
  1999年   6452篇
  1998年   1874篇
  1997年   1755篇
  1996年   1506篇
  1995年   1379篇
  1994年   1239篇
  1993年   1277篇
  1992年   4102篇
  1991年   3914篇
  1990年   3941篇
  1989年   3684篇
  1988年   3293篇
  1987年   3246篇
  1986年   3112篇
  1985年   2924篇
  1984年   2180篇
  1983年   1790篇
  1982年   1061篇
  1981年   1023篇
  1979年   2055篇
  1978年   1528篇
  1977年   1277篇
  1976年   1077篇
  1975年   1323篇
  1974年   1378篇
  1973年   1362篇
  1972年   1239篇
  1971年   1144篇
  1970年   1019篇
  1969年   944篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Sticky platelet syndrome (SPS) leads to hyperaggregabilty of platelets in response to physiologic stimuli. In this report we describe three patients with clinical symptoms of SPS after renal transplantation. The first patient developed an infarction of her transplant kidney with additional, subsequent renal microinfarctions. The second patient suffered multiple strokes and deep vein thrombosis with episodes of pulmonary embolism and ischemic bowel disease due to colonic microinfarctions. The third patient experienced a long episode of unexplained respiratory and graft dysfunction immediately after transplantation until therapy for SPS was initiated, at which point symptoms resolved quickly. Kidney transplant recipients with SPS may be at increased risk of developing thrombosis, given that most immunosuppressive drugs are known to induce either endothelial cell damage or augment platelet aggregation. All patients awaiting renal transplantation should be screened for a history of thrombosis and, if appropriate, tested for SPS. Affected patients should receive dose-adjusted acetylsalicylic acid.  相似文献   
93.
94.
HYPOTHESIS: Based on recent findings on the association between vascular risk factors and hippocampal atrophy, we hypothesized that hypertension and diabetes mellitus (DM) are associated with medial temporal lobe atrophy (MTA) in subjects without disability, independent of the severity of white matter hyperintensities. METHODS: In the Leukoaraiosis And DISability in the elderly (LADIS) study, we investigated the relationships between DM, hypertension, blood pressure and MTA in 582 subjects, stratified by white matter hyperintensity severity, using multinomial logistic regression. MTA was visually scored for the left and right medial temporal lobe (score 0-4), and meaned. RESULTS: Mean age was 73.5 years (sd 5.1), 54% was female. Of the subjects, 15% had DM, and 70% had a history of hypertension. The likelihood of having MTA score 3 was significantly higher in subjects with DM (OR 2.9; 95% CI: 1.1-7.8) compared with an MTA score of 0 (no atrophy). The odds ratio for MTA score 2 was not significantly increased (OR 1.8; CI: 0.9-4). Systolic and diastolic blood pressure and a history of hypertension were not associated with MTA. There was no interaction between DM and hypertension. Stratification on white matter hyperintensities (WMH) did not alter the associations. CONCLUSION: Our study strengthens the observation that MTA is associated with DM, independently of the amount of small vessel disease as reflected by WMH.  相似文献   
95.
This study examined the structure and symptom correlates of perfectionism in a sample of 6th-grade, urban, African American children using the Child and Adolescent Perfectionism Scale (CAPS; Flett, Hewitt, Boucher, Davidson, & Munro, 2000). Confirmatory factor analysis showed inadequate fit of the original subscales. Exploratory factor analysis suggested 3 dimensions of perfectionism: A Socially Prescribed and a Self-Oriented-Critical factor were described as maladaptive, whereas a Self-Oriented-Striving factor was proposed as adaptive. Cross-sectional correlations among the perfectionism dimensions and symptoms of psychopathology fit well with the adaptive versus maladaptive model. In addition, Socially Prescribed Perfectionism showed a robust predictive relation to 7th-grade internalizing symptoms, especially depression, in boys. Results are discussed in the context of the cultural and socioeconomic characteristics of this African American sample and suggestions for future research are provided.  相似文献   
96.
Presented in this work is a rare injury of a blunt abdominal trauma in a child. Besides a partial rupture of the kidney and a retro-/intraperitoneal haematoma, a further injury occurred from the accident: an initially clinically indetectable tear of the A. iliaca communis which was found intraoperatively and with systematic CT analysis. Traumatic blood vessel lesions of the abdominal aorta and in particular the iliac blood vessels are very rare in children. By such violent impact injuries, it is therefore vital to perform a clinical examination of the foot pulse, systematic analysis of radiology diagnostics, and intraoperative exploration. The growth phase should be considered for therapy of the blood vessels depending on the child's age group. As the long-term results of graft implants are practically unknown, if possible a primary suture or vein patch should be performed.  相似文献   
97.
98.
By oxygen concentration measurements (Oximeter Oxydig Dräger, Lübeck) in the EC 145 helicopter two oxygen transport and application systems were compared. The new liquid oxygen system (LOX) for the oxygen therapy was assessed in an application observation. For physical reasons fluid oxygen evaporates during the stand-by phase and an increased concentration (22.8% O2) in the exhaust valve of LOX arises. On the other hand a high oxygen concentration (22.7% O2) was measured in the operation mode of the conventional pressure flask gas system (GAS). No increased concentration could be measured within the helicopter cabin (HEMS, PAX) comparing both oxygen systems. For transport and application of oxygen with a very big reserve for the air dependent intensive transport the results show that LOX is a sure low pressure system (3.4 bar).  相似文献   
99.
Objective To describe the clinical presentation of acute diverticulitis in an emergency department and to characterize the natural history of diverticulitis in the short perspective. Comparisons are made with an important differential diagnosis, nonspecific abdominal pain (NSAP). Method Patients admitted to our hospital with abdominal pain of up to 7 days’ duration were registered prospectively using a detailed schedule for history, symptoms and signs, from 1 February 1997 to 1 June 2000. Of 3349 patients initially included, 3073 (92%) were eligible for follow up after 1–3 years. Results Acute diverticulitis was the final diagnosis in 145 patients and NSAP in 1142 patients. The incidence of hospitalized patients with diverticulitis was 47 per year and 100 000 population, with a mean hospital stay of 3.3 days. Patients with diverticulitis, more frequently than NSAP, had a longer history and laboratory signs of inflammatory activity. Isolated left abdominal tenderness was more common in diverticulitis, whereas isolated right abdominal tenderness was more common in NSAP. Duration of symptoms on arrival was independent of age and was not correlated to C‐reactive protein, leucocytes or body temperature. Sensitivity of diverticulitis as primary diagnosis was 64% and specificity 97%. Corresponding figures for NSAP were 43% and 90% respectively. Age and gender did not influence diagnostic accuracy or risk of surgery. Conclusion Diverticulitis differs significantly from NSAP in clinical presentation and laboratory parameters. Sensitivity of primary diagnosis for diverticulitis and NSAP was low.  相似文献   
100.
BACKGROUND: Fractures of the mandible are a common form of facial injury. The aetiological factors associated with mandibular fractures and the trends in these factors over a 10-year period are reported. METHODS: A retrospective survey was carried out of 724 patients presenting with a fracture of the mandible over the 10-year-period 1994-2003. Patients; records were reviewed and analyzed according to age, sex, cause of injury, anatomic site of fracture, treatment and postoperative complications. RESULTS: Over the 10-year-period the rate of mandibular fractures remained constant (mean 40,7%). There were no changes in the age group (mean 33,3 years) or in the higher prevalence in male (male-female-ratio 2,3 : 1). The major causes of fractures were assaults (38,6%) and accidental fall (27,3%). The most common fracture site was the condylar region (47,0%) followed by the angle (29,4%). Most fractures were treated by closed reduction until 2002, thereafter surgical treatment increased noticeable. The complication rate was 8,9% and the most common complications were hardware exposure and infection. CONCLUSION: Fractures of the mandible are a prevalent form of facial injury. Aetiological factors show no significant change over the 10-year-period. Complication-rate is low and will support the tendency towards surgical treatment.  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