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   6850篇
  免费   1331篇
  国内免费   20篇
耳鼻咽喉   158篇
儿科学   35篇
妇产科学   34篇
基础医学   86篇
口腔科学   6574篇
临床医学   162篇
内科学   198篇
皮肤病学   72篇
神经病学   74篇
特种医学   27篇
外科学   506篇
综合类   8篇
预防医学   98篇
眼科学   24篇
药学   30篇
中国医学   5篇
肿瘤学   110篇
  2024年   28篇
  2023年   347篇
  2022年   25篇
  2021年   42篇
  2020年   127篇
  2019年   52篇
  2018年   249篇
  2017年   342篇
  2016年   380篇
  2015年   462篇
  2014年   464篇
  2013年   463篇
  2012年   264篇
  2011年   255篇
  2010年   350篇
  2009年   552篇
  2008年   247篇
  2007年   195篇
  2006年   195篇
  2005年   146篇
  2004年   136篇
  2003年   191篇
  2002年   146篇
  2001年   184篇
  2000年   157篇
  1999年   170篇
  1998年   232篇
  1997年   203篇
  1996年   196篇
  1995年   176篇
  1994年   169篇
  1993年   126篇
  1992年   139篇
  1991年   85篇
  1990年   92篇
  1989年   55篇
  1988年   84篇
  1987年   78篇
  1986年   37篇
  1985年   60篇
  1984年   59篇
  1983年   57篇
  1982年   51篇
  1981年   32篇
  1978年   11篇
  1977年   10篇
  1976年   11篇
  1975年   15篇
  1974年   12篇
  1972年   11篇
排序方式: 共有8201条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
The National Collegiate Athletic Association (NCAA) mandates the use of brightly colored, intraoral mouth- guards by football players to reduce the frequency and severity of craniofacial and intraoral morbidity and mortality, and to enhance the ability of officials to observe player compliance. The purpose of this 12-question mail survey was to determine the attitudes of on-Held game officials regarding current NCAA mouthguard regulations and patterns of utilization by college football players. The sample consisted of all 50 Big East Football Conference officials; a response rate of 100 percent was achieved. Only 42 percent of the officials reported observing all players in compliance, and quarterbacks were identified by others as the least compliant group (52%). The majority (88%) indicated that the 1990 rule for brightly colored mouthguards had been beneficial to them in determining player compliance, and 52 percent reported that this rule had resulted in more frequent use by these athletes. Nearly all officials (96%) indicated that they would issue a warning for noncompliance to the player or coach, rather than charging a timeout for a violation as prescribed by NCAA regulations. The majority (70%) believe current enforcement is appropriate, but expressed the opinion that coaches should be held more accountable for player compliance.  相似文献   
85.
86.
In Vitro Wear of Nano-Composite Denture Teeth   总被引:2,自引:0,他引:2  
PURPOSE: Few laboratory tests have been able to substantiate and quantify the wear resistances of polymeric denture teeth. This study evaluated the relative wear resistance of several types of denture teeth using an in vitro wear testing device. MATERIAL AND METHODS: Four different types of denture teeth [nano-filled (Veracia) and micro-filled composites (SR-Orthosit, Endura, Duradent, Surpass), cross-linked acrylic (SR-Postaris, Genios-P, Creapearl, Vitapan Physiodens, Premium 8, Integral), and a conventional acrylic (Biotone)] were used. The flattened buccal surface of each denture tooth was subjected to the evaluation of Knoop hardness (n=5) and localized wear for 100,000 cycles (n=10). Wear values were determined in micrometers using a profilometer. The data for the hardness, wear depth, and worn surface areas were individually analyzed by one-way ANOVA. RESULTS: Knoop hardness values (KHN) ranged from 28.2 to 29.8 for micro-filled composite, 18.9 to 21.6 for cross-linked acrylic, 22.7 for nano-composite, and 18.6 for conventional acrylic teeth. All micro-filled composite teeth were significantly harder than other teeth (p <0.0001). The wear depth values were 90.5 microm for the nano-composite, 69.8 to 93.0 microm for the micro-filled composite, 80.8 to 104.0 microm for the cross-linked acrylic, and 162.5 microm for conventional acrylic teeth. The worn surface areas were 5.1 mm2 for the nano-composite, 2.6 to 3.6 mm2 for the micro-filled composite, 4.4 to 5.7 mm2 for the cross-linked acrylic, and 10.1 mm2 for conventional acrylic teeth. The wear values of the acrylic control were significantly different from all other denture teeth (p <0.001). CONCLUSION: The nano-composite tooth was harder and more wear resistant than the acrylic teeth but not significantly different from most of the cross-linked and micro-filled composite teeth tested.  相似文献   
87.
88.
89.
90.
Problems that can occur when single implants are utilized to restore first molar teeth include the frequent loosening of screws, as well as screws and/or implant breakage. These may result from torquing and rotational movements of the prosthesis during masticatory and parafunctional mandibular movements. When sufficient bone and mesio-distal restorative space is present, the placement of two implants should be considered.  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