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   3445篇
  免费   206篇
  国内免费   30篇
耳鼻咽喉   20篇
儿科学   152篇
妇产科学   51篇
基础医学   402篇
口腔科学   104篇
临床医学   268篇
内科学   904篇
皮肤病学   236篇
神经病学   230篇
特种医学   190篇
外科学   500篇
综合类   17篇
预防医学   256篇
眼科学   16篇
药学   202篇
中国医学   2篇
肿瘤学   131篇
  2023年   20篇
  2022年   24篇
  2021年   56篇
  2020年   30篇
  2019年   59篇
  2018年   80篇
  2017年   45篇
  2016年   72篇
  2015年   66篇
  2014年   106篇
  2013年   162篇
  2012年   155篇
  2011年   155篇
  2010年   116篇
  2009年   127篇
  2008年   128篇
  2007年   138篇
  2006年   138篇
  2005年   122篇
  2004年   106篇
  2003年   107篇
  2002年   99篇
  2001年   63篇
  2000年   80篇
  1999年   94篇
  1998年   93篇
  1997年   72篇
  1996年   75篇
  1995年   66篇
  1994年   69篇
  1993年   50篇
  1992年   95篇
  1991年   50篇
  1990年   70篇
  1989年   68篇
  1988年   77篇
  1987年   54篇
  1986年   55篇
  1985年   28篇
  1984年   48篇
  1983年   27篇
  1982年   24篇
  1981年   29篇
  1980年   24篇
  1978年   16篇
  1977年   15篇
  1976年   15篇
  1973年   15篇
  1966年   14篇
  1964年   14篇
排序方式: 共有3681条查询结果,搜索用时 15 毫秒
91.
92.
The authors hypothesized that age, body mass index (BMI), and medical comorbidities (graded with the Charleson Comorbidiy index [CCI]) could be used to predict early complications after TSA. The authors performed a retrospective review of primary TSAs with a minimum of 90-day follow-up. One hundred twenty-seven patients met the inclusion criteria. Complications occurred in 12 (9.4%) of patients. Major complications occurred in 1 patient (0.8%), medical in 8 (6.3%), and surgical in 4 (3.1%). CCI significantly correlated with complication rates and multivariate regression analysis demonstrated CCI to be the only significant determinant of overall complication rates (P = 0.005) and medical complication rates (P = 0.015). While BMI subgroup did not affect complication rates, transfusion rates, intra-operative blood loss, or operative time, our study may have been underpowered for this variable.  相似文献   
93.

Introduction

Laparoscopic Heller-Dor surgery is the current treatment of choice for patients with esophageal achalasia, but elderly patients are generally referred for less invasive treatments (pneumatic dilations or botulinum toxin injections).

Aim

To assess the effect of age on the surgical outcome of patients receiving laparoscopic Heller-Dor as primary treatment.

Methods

Demographic and clinical findings were prospectively collected on patients undergoing laparoscopic Heller-Dor from 1992 to 2012. Patients were classified in three age brackets: group A (≤45 years), group B (45–70), and group C (≥70). Treatment was defined as a failure if the postoperative symptom score was >10th percentile of the preoperative score (i.e., >8). We consecutively performed the Heller-Dor in 571 achalasia patients, 305 (53.4 %) in group A, 226 (39.6 %) in group B, and 40 (7 %) in group C.

Results

The mortality was nil; the conversion and morbidity rates were both 1.1 %. Group C patients had higher preoperative symptom scores (p?=?0.02), while the symptom duration was similar in all three groups. Mucosal tears occurred in 17 patients (3 %): 6 (2 %) in group A, 8 (3.5 %) in group B, and 3 (7.5 %) in group C (p?=?0.09). The postoperative hospital stay was slightly longer for group C (p?=?0.06).

Discussion

The treatment failure rate was quite similar: 31 failures in group A (10.1 %), 19 in group B (8.4 %), and 3 in group C (7.5 %; p?=?0.80). These failures were seen more in manometric pattern III (22.2 %, p?=?0.002). Laparoscopic Heller-Dor can be used as the first therapeutic approach to achalasia even in elderly patients with an acceptable surgical risk.  相似文献   
94.
BackgroundIt is unclear whether patients with inflammatory bowel disease (IBD) are at increased risk of COVID-19.ObjectivesThis observational study compared the prevalence of COVID-19 symptoms, diagnosis and hospitalization in IBD patients with a control population with non-inflammatory bowel disorders.MethodsThis multicentre study, included 2733 outpatients (1397 IBD patients and 1336 controls), from eight major gastrointestinal centres in Lombardy, Italy. Patients were invited to complete a web-based questionnaire regarding demographic, historical and clinical features over the previous 6 weeks. The prevalence of COVID-19 symptoms, diagnosis and hospitalization for COVID-19 was assessed.Results1810 patients (64%) responded to the questionnaire (941 IBD patients and 869 controls). IBD patients were significantly younger and of male sex than controls. NSAID use and smoking were more frequent in controls. IBD patients were more likely treated with vitamin-D and vaccinated for influenza. Highly probable COVID-19 on the basis of symptoms and signs was less frequent in the IBD group (3.8% vs 6.3%; OR:0.45, 95%CI:0.28–0.75). IBD patients had a lower rate of nasopharyngeal swab-PCR confirmed diagnosis (0.2% vs 1.2%; OR:0.14, 95%CI:0.03–0.67). There was no difference in hospitalization between the groups (0.1% vs 0.6%; OR:0.14, 95%CI:0.02–1.17).ConclusionIBD patients do not have an increased risk of COVID-19 specific symptoms or more severe disease compared with a control group of gastroenterology patients.  相似文献   
95.
Romeo  V.  Sarno  L.  Volpe  A.  Ginocchio  M. I.  Esposito  R.  Mainenti  P. P.  Petretta  M.  Liuzzi  R.  D’Armiento  M.  Martinelli  P.  Brunetti  A.  Maurea  S. 《Abdominal imaging》2019,44(10):3398-3407
Purpose

To compare the performance US and MR in identifying placental adhesion spectrum (PAS) in placenta previa (PP) and to establish a potential method of image interpretation.

Methods

US and MR examinations of 51 patients with PP were selected. The presence of imaging signs commonly used to detect PAS was assessed. Penalized logistic regression was performed considering histology as standard of reference; only signs statistically significant (p < 0.05) were considered for ROC and multivariate analysis. The probability of PAS according to the presence of US and/or MR signs was then assessed.

Results

At univariate analysis, loss of retroplacental clear space, myometrial thinning (MT) and placenta lacunar spaces on US, intraplacental dark bands (IDBs), focal interruption of myometrial border (FIMB) and abnormal vascularity (AV) on MR were statistically significant (p < 0.01). Three diagnostic methods for PAS were then developed for both US and MR when at least one (Method 1), two (Method 2) or three (Method 3) imaging signs occurred, respectively. Method 2 for MR showed a significantly (p < 0.05) higher accuracy (91%) compared to the other methods. When MR IDBs and AV as well as IDBs and FIMB were present in combination with US MT the probability of PAS increased from 75 to 90% and from 80 to 91%, respectively.

Conclusion

MR demonstrated a higher diagnostic accuracy than US to detect PAS. However, since the combination of MR and US signs could improve the probability to detect PAS, a complementary diagnostic role of these techniques could be considered.

  相似文献   
96.
97.
A human-hamster cell hybrid carrying a single copy of chromosome 16 as the only human genetic material was irradiated with a single dose of gamma-rays (7000 rads; 1 rad = 0.01 Gy) and then fused with a thymidine kinase-deficient hamster cell line (RJKM) to generate radiation hybrids retaining unselected fragments of this human chromosome. In two experiments, 223 hybrids were isolated in hypoxanthine/aminopterine/thymidine (HAT) medium and screened with 38 DNA probes, corresponding to anonymous DNA or gene sequences localized on chromosome 16. The most likely order and location of the 38 DNA sequences were established by multiple pairwise analysis and scaled to estimate physical distance in megabases. The order and the distances thus obtained are mostly consistent with available data on genetic and physical mapping of these markers, illustrating the usefulness of radiation hybrids for mapping.  相似文献   
98.
99.
100.
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