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   180929篇
  免费   12410篇
  国内免费   1255篇
耳鼻咽喉   2354篇
儿科学   3849篇
妇产科学   4448篇
基础医学   26774篇
口腔科学   3648篇
临床医学   18018篇
内科学   34129篇
皮肤病学   4610篇
神经病学   14516篇
特种医学   8367篇
外科学   23524篇
综合类   2401篇
现状与发展   5篇
一般理论   127篇
预防医学   12488篇
眼科学   4653篇
药学   15039篇
中国医学   1625篇
肿瘤学   14019篇
  2023年   934篇
  2022年   2297篇
  2021年   5277篇
  2020年   2801篇
  2019年   4113篇
  2018年   4973篇
  2017年   3682篇
  2016年   4648篇
  2015年   6153篇
  2014年   7667篇
  2013年   9442篇
  2012年   14180篇
  2011年   13894篇
  2010年   8116篇
  2009年   6899篇
  2008年   10576篇
  2007年   10578篇
  2006年   9825篇
  2005年   9324篇
  2004年   8451篇
  2003年   7399篇
  2002年   6503篇
  2001年   4545篇
  2000年   4150篇
  1999年   3416篇
  1998年   1533篇
  1997年   1181篇
  1996年   1093篇
  1995年   997篇
  1994年   854篇
  1993年   769篇
  1992年   1652篇
  1991年   1646篇
  1990年   1417篇
  1989年   1300篇
  1988年   1208篇
  1987年   1081篇
  1986年   1053篇
  1985年   932篇
  1984年   697篇
  1983年   632篇
  1982年   474篇
  1981年   440篇
  1980年   408篇
  1979年   562篇
  1978年   447篇
  1977年   427篇
  1976年   387篇
  1974年   397篇
  1973年   371篇
排序方式: 共有10000条查询结果,搜索用时 750 毫秒
61.
62.
63.
Sometimes the clinical differentiation between verruca plana (VP) and VP‐like seborrheic keratosis (SK) could be challenged. However, there have been no studies on this issue to date. The aim of this study was to elucidate clinical and dermoscopic differences between these two diseases, and also to suggest a diagnostic algorithm of VP and VP‐like SK without skin biopsy. The patients who had lesions clinically considered as VP or VP‐like SK were the target of our study. We took clinical and dermoscopic photos with informed consent and conducted a questionnaire. All patients had their diagnoses confirmed by biopsy. Thirty‐three patients were enrolled in our study. Seventeen patients were finally diagnosed with VP (51.5%) and 16 patients with VP‐like SK (48.5%). In clinical findings, VP‐like SK showed significantly more scattered distribution than VP (P = 0.039), which exhibited more clustered or grouped distribution (P = 0.039). In dermoscopic findings, brain‐like appearance was more commonly observed in VP‐like SK (P = 0.003) whereas VP showed more red dots or globular vessels (P = 0.017) and even‐colored light brown to yellow patch (P < 0.001). Sex, onset age, the size of each lesion, location, color and shape showed no significant differences between them (P > 0.05). Based on our results, we suggest a diagnostic algorithm using Koebner's phenomenon, dermoscopic findings, distribution of each lesion and biopsy for multiple VP‐like lesions in adults, and we think it will be a very useful diagnostic tool in daily clinical dermatological practice.  相似文献   
64.
65.
66.
Fluid is usually restricted during thoracic surgery, and vasoactive agents are often administered to maintain blood pressure. One-lung ventilation (OLV) decreases arterial oxygenation; thus oxygen delivery to the brain can be decreased. In this study, we compared phenylephrine and dopamine with respect to maintaining cerebral oxygenation during OLV in major thoracic surgery.Sixty-three patients undergoing lobectomies were randomly assigned to the dopamine (D) or phenylephrine (P) group. The patients’ mean arterial pressure was maintained within 20% of baseline by a continuous infusion of dopamine or phenylephrine. Maintenance fluid was kept at 5 mL/kg/h. The depth of anesthesia was maintained with desflurane 1MAC and remifentanil infusion under bispectral index guidance. Regional cerebral oxygen saturation (rScO2) and hemodynamic variables were recorded using near-infrared spectroscopy and esophageal cardiac Doppler.The rScO2 was higher in the D group than the P group during OLV (OLV 60 min: 71 ± 6% vs 63 ± 12%; P = 0.03). The number of patients whose rScO2 dropped more than 20% from baseline was 0 and 6 in the D and P groups, respectively (P = 0.02). The D group showed higher cardiac output, but lower mean arterial pressure than the P group (4.7 ± 1.0 vs 3.9 ± 1.2 L/min; 76.7 ± 8.1 vs 84.5 ± 7.5 mm Hg; P = 0.02, P = 0.02). Among the variables, age, hemoglobin concentration, and cardiac output were associated with rScO2 by correlation analysis.Dopamine was superior to phenylephrine in maintaining cerebral oxygenation during OLV in thoracic surgery.  相似文献   
67.
68.
69.
Recent studies have reported an association between gastroesophageal reflux disease (GERD) and atrial fibrillation (AF). The objective of the present study was to evaluate whether AF is one of the risk factors for GERD occurrence.In this hospital-based, retrospective, case–control study, the patients were classified into 2 groups. The patients diagnosed with new AF were assigned to the AF group (n = 1612); those diagnosed without AF and GERD were assigned to the control group (n = 1612). The subjects in the control group were selected from outpatients of total healthcare center without a history of AF or GERD, and matched for age and gender. We evaluated the incidence of GERD and risk factors for GERD occurrence between the 2 groups.The number of patients experiencing occurrence of GERD during the follow-up period was significantly higher in the AF group than those in the control group, respectively (129 patients vs 98 subjects, P = 0.037). The incidence of GERD was significantly higher in the AF group than in the control group by Kaplan–Meier analysis with log-rank test (P = 0.008). The AF group''s adjusted hazard ratio of GERD occurrence against that of the control group was 1.37 (95% confidence interval [CI]: 1.16–1.57; P = 0.009) according to Cox''s proportional hazard model.The presence of AF appears to increase the incidence of GERD and may be considered a risk factor for the development of GERD. Further, large prospective and cohort studies will be required to better establish the correlation of GERD with AF.  相似文献   
70.
The cingulum, connecting the orbitofrontal cortex to the medial temporal lobe, involves in diverse cognition functions including attention, memory, and motivation. To investigate the relationship between the cingulum injury and cognitive impairment in patients with chronic mild traumatic brain injury, we evaluated the integrity between the anterior cingulum and the basal forebrain using diffusion tensor tractography in 73 patients with chronic mild traumatic brain injury(39 males, 34 females, age 43.29 ± 11.42 years) and40 healthy controls(22 males, 18 females, age 40.11 ± 16.81 years). The patients were divided into three subgroups based on the integrity between the anterior cingulum and the basal forebrain on diffusion tensor tractography: subgroup A(n = 19 patients)-both sides of the anterior cingulum were intact; subgroup B(n= 36 patients)-either side of the anterior cingulum was intact; and subgroup C(18 patients)-both sides of the anterior cingulum were discontinued. There were significant differences in total Memory Assessment Scale score between subgroups A and B and between subgroups A and C. There were no significant differences in diffusion tensor tractography parameters(fractional anisotropy, apparent diffusion coefficient, and fiber volume) between patients and controls. These findings suggest that the integrity between the anterior cingulum and the basal forebrain, but not diffusion tensor tractography parameter, can be used to predict the cognitive function of patients with chronic mild traumatic brain injury. This study was approved by Yeungnam University Hospital Institutional Review Board(approval No. YUMC-2014-01-425-010) on August 16, 2017.  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