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   21580篇
  免费   1402篇
  国内免费   280篇
耳鼻咽喉   311篇
儿科学   321篇
妇产科学   250篇
基础医学   3447篇
口腔科学   260篇
临床医学   1874篇
内科学   4450篇
皮肤病学   759篇
神经病学   1654篇
特种医学   1742篇
外科学   2804篇
综合类   138篇
一般理论   13篇
预防医学   692篇
眼科学   616篇
药学   1800篇
中国医学   265篇
肿瘤学   1866篇
  2024年   14篇
  2023年   164篇
  2022年   511篇
  2021年   771篇
  2020年   398篇
  2019年   573篇
  2018年   712篇
  2017年   578篇
  2016年   866篇
  2015年   1245篇
  2014年   1406篇
  2013年   1540篇
  2012年   2118篇
  2011年   2067篇
  2010年   1326篇
  2009年   1071篇
  2008年   1348篇
  2007年   1282篇
  2006年   1148篇
  2005年   1055篇
  2004年   845篇
  2003年   708篇
  2002年   608篇
  2001年   107篇
  2000年   109篇
  1999年   70篇
  1998年   92篇
  1997年   73篇
  1996年   62篇
  1995年   41篇
  1994年   33篇
  1993年   32篇
  1992年   33篇
  1991年   41篇
  1990年   18篇
  1989年   16篇
  1988年   15篇
  1987年   13篇
  1986年   23篇
  1985年   10篇
  1984年   8篇
  1983年   20篇
  1982年   21篇
  1981年   9篇
  1980年   6篇
  1978年   4篇
  1976年   6篇
  1973年   6篇
  1972年   9篇
  1971年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Conclusion: The results of the present investigation suggest that modification of HA could improve efficiency and durability in augmentation laryngoplasty. Objectives: Injection laryngoplasty (IL) is one of the most suitable options for treatment of glottic insufficiency, which is caused by vocal fold (VF) paralysis, atrophy, or scarring. Hyaluronic acid (HA) is a widely used material for VF injection. This study was intended to evaluate the durability and efficiency of HA of different particle sizes for VF augmentation. Methods: Three types of HA, Restylane®, monophasic low-viscosity, and unequal particle-sized middle-viscosity HA were injected into the left VF of three groups with eight rabbits each. Results: After 6 and 10 weeks, the injected site was evaluated endoscopically, histologically, radiologically, and functionally. None of the 24 rabbits showed any signs of respiratory distress. Computed tomography (CT) images and endoscopic evaluation revealed sufficient augmented volume of the injected VF in all treated groups 6 weeks after the injection. Histological data at week 10 showed that unequal particle-sized HA did not migrate from its original injection site, while other HAs migrated to the periphery of the arytenoid cartilage. Videokymographic analysis showed more favorable vibrations of unequal particle-sized HA injected VF mucosa 10 weeks post-injection, compared to the other treatment groups.  相似文献   
62.
63.
Vanadium dioxide (VO2) is one of the extensively studied strongly correlated oxides due to its intriguing insulator–metal transition near room temperature. In this work, we investigated temperature-dependent nanoscale conduction in an epitaxial VO2 film grown on an Al2O3 substrate using conductive-atomic force microscopy (C-AFM). We observed that only the regions near the grain boundaries are conductive, producing intriguing donut patterns in C-AFM images. Such donut patterns were observed in the entire measured temperature range (300–355 K). The current values near the grain boundaries increased by approximately two orders of magnitude with an increase in the temperature, which is consistent with the macroscopic transport data. The spatially-varied conduction behavior is ascribed to the coexistence of different monoclinic phases, i.e., M1 and M2 phases, based on the results of temperature-dependent Raman spectroscopy. Furthermore, we investigated the conduction mechanism in the relatively conductive M1 phase regions at room temperature using current–voltage (IV) spectroscopy and deep data analysis. Bayesian linear unmixing and k-means clustering showed three distinct types of conduction behavior, which classical C-AFM cannot resolve. We found that the conduction in the M1 phase regions can be explained by the Poole–Frenkel mechanism. This work provides deep insight into IMT behavior in the epitaxial VO2 thin film at the nanoscale, especially the coexistence and evolution of the M1 and M2 phases. This work also highlights that IV spectroscopy combined with deep data analysis is very powerful in investigating local transport in complex oxides and various material systems.

We investigated temperature-dependent nanoscale conduction in an epitaxial VO2 film grown on an Al2O3 substrate using conductive-atomic force microscopy and deep data analysis.  相似文献   
64.
65.
STUDY OBJECTIVE: To examine the incidence, characteristics, and treatment of ureteral injuries during classic intrafascial supracervical hysterectomy for benign gynecologic diseases. DESIGN: Retrospective study (Canadian Task Force classification II-3). SETTING: Department of obstetrics and gynecology, university teaching hospital. PATIENTS: A total of 1163 women with benign gynecologic diseases. INTERVENTIONS: Classic intrafascial supracervical hysterectomy. MEASUREMENTS AND MAIN RESULTS: A retrospective chart review was conducted to determine the rate of ureteral injury. Four cases of ureteral injuries occurred among the 1163 classic intrafascial supracervical hysterectomy procedures (0.34%). Ureteral injury occurred during peritoneal dissection in 1 case, which was treated immediately with laparoscopy. In 2 cases, ureteral injuries were recognized by watery vaginal discharge several days after the operation and were treated with laparotomy procedures. Ureteral injury was not detected postoperatively in another case, resulting in a laparoscopic nephrectomy caused by a nonfunctioning kidney 3 years after the initial operation. The predisposing factors for ureteral injury were adhesion as a result of endometriosis, and earlier surgery in which the normal pelvic anatomy was distorted. CONCLUSION: The incidence of ureteral injury during classic intrafascial supracervical hysterectomy as noted in this study is 0.34%. Postoperative cases were associated with high morbidity. Early detection of ureteral injury is crucial for appropriate management as intraoperative diagnosis and repair of the injury then has fewer consequences and less serious complications than postoperative cases.  相似文献   
66.
67.
68.
69.
70.
The incidence of gastric cancer is high in Korea, and dietary factors are important risk factors for gastric cancer. This study examined whether gastric cancer risk was related to dietary factors that directly irritate the stomach wall. This case–control study consisted of 308 matched pairs of gastric cancer cases and controls recruited from 2002 to 2006 at two hospitals in Korea. Dietary assessments were completed using a food frequency questionnaire and a dietary habit questionnaire. Gastric cancer risk was increased for high meal frequency of >3 vs. low meal frequency of ≤3 times per day, overeating vs. not overeating, and preferred vs. not preferred spicy or salty foods. Furthermore, participants with dietary factors of high meal frequency, overeating, and preference for spicy or salty foods elevated the risk of gastric cancer compared to those with low meal frequency, not overeating, and not preferring spicy or salty foods, simultaneously. In conclusion, gastric cancer risk was significantly increased in people with dietary factors that irritate the stomach wall, such as high meal frequency, overeating, and preference for spicy or salty foods.  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