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   17259篇
  免费   1452篇
  国内免费   171篇
耳鼻咽喉   63篇
儿科学   64篇
妇产科学   20篇
基础医学   425篇
口腔科学   14689篇
临床医学   408篇
内科学   590篇
皮肤病学   170篇
神经病学   69篇
特种医学   172篇
外科学   423篇
综合类   927篇
预防医学   583篇
眼科学   7篇
药学   203篇
  6篇
中国医学   26篇
肿瘤学   37篇
  2023年   470篇
  2022年   425篇
  2021年   751篇
  2020年   763篇
  2019年   829篇
  2018年   718篇
  2017年   732篇
  2016年   722篇
  2015年   708篇
  2014年   1009篇
  2013年   1058篇
  2012年   799篇
  2011年   813篇
  2010年   614篇
  2009年   624篇
  2008年   635篇
  2007年   606篇
  2006年   553篇
  2005年   501篇
  2004年   435篇
  2003年   429篇
  2002年   376篇
  2001年   330篇
  2000年   270篇
  1999年   231篇
  1998年   245篇
  1997年   260篇
  1996年   245篇
  1995年   193篇
  1994年   163篇
  1993年   170篇
  1992年   208篇
  1991年   164篇
  1990年   147篇
  1989年   159篇
  1988年   165篇
  1987年   137篇
  1986年   134篇
  1985年   143篇
  1984年   106篇
  1983年   97篇
  1982年   85篇
  1981年   83篇
  1980年   97篇
  1979年   81篇
  1978年   67篇
  1977年   80篇
  1976年   68篇
  1975年   57篇
  1974年   65篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
人龋病牙髓中神经肽与抗原呈递细胞的动态研究   总被引:1,自引:0,他引:1  
目的 :研究人龋病牙髓中降钙素基因相关肽 (Calicitoningene -relatedpeptide,CGRP)和树突状细胞(Dendriticcells,DC)、P物质 (SubstanceP,SP)和血管内皮细胞(Endothelialcells,EC)之间的空间变化特点 ,以探明牙髓病理状态下神经免疫间的相互作用。方法:采用免疫组化法观察龋病不同阶段牙髓中上述物质的变化 ,并对前、后两种物质分别进行双标免疫组化染色。结果:(1)4个指标的数量在不同组间比较差别有统计学意义 (P<0.05)。 (2)双标染色显示 :龋病牙髓中神经肽与抗原呈递细胞共聚集在龋坏相应冠髓的造牙本质细胞层下 ,CGRP接触或包绕树突状细胞 ;而SP随龋坏深入逐渐接近血管并与管壁接触。结论:龋源性刺激引起牙髓中CGRP、SP、DC、EC的局部相互作用加强共同调节牙髓免疫反应  相似文献   
62.
顺丁烯二酸酐改性环氧二甲基丙烯酸酯的合成与应用   总被引:2,自引:0,他引:2  
为了合成顺丁烯二酸酐改性的环氧二甲基丙烯酸酯树脂及其物理机械性能。按量取E51环氧树脂、甲基丙烯酸、顺丁烯二酸酐,与催化剂N,N-二甲基苄胺一起进行反应。检测了由合成EAM单体或EMA单体配制复合树脂的压缩强度、径向拉伸强度、表面硬度、固化深度、吸水值和水溶解值。与EMA单体比较,含EAM单体的复合树脂明显增强了压缩强度、径向拉伸强度、表面硬度、固化深度值,降低了吸水值和水溶解值。  相似文献   
63.
一种简易净水装置,解决没有配备滤水装置的牙科综合治疗机经常出现的手机脏堵问题。  相似文献   
64.
牙乳头细胞来源于外胚间充质,具有多向分化潜能,是体内唯一分化为成牙本质细胞的前体细胞。该细胞在牙发育和牙体牙髓损伤修复过程中起重要作用。牙乳头细胞相关的组织工程化研究是近年来的热点。下面就牙乳头细胞的形态及其功能特征、三维细胞培养、组织工程化牙研究进展等方面的研究作一综述。  相似文献   
65.
Osseodensification is a new method of bone instrumentation for dental implant placement that preserves bulk bone and increases primary implant stability, and may accelerate the implant rehabilitation treatment period and provide higher success and survival rates than conventional methods. The aim of this retrospective study was to evaluate and discuss results obtained on immediate implant placement with immediate and delayed loading protocols under Osseodensification bone instrumentation. This study included private practice patients that required dental implant rehabilitation, between February 2017 and October 2019. All implants were placed under Osseodensification and had to be in function for at least 12 months to be included on the study. A total of 211 implants were included in the study, with a 98.1% total survival rate (97.9% in the maxilla and 98.5% in the mandible). For immediate implants with immediate load, 99.2% survival rate was achieved, and 100% survival rate for immediate implant placement without immediate load cases. A total of four implants were lost during this period, and all of them were lost within two months after placement. Within the limitations of this study, it can be concluded that Osseodensification bone instrumentation provided similar or better results on survival rates than conventional bone instrumentation.  相似文献   
66.
目的 比较牙体牙髓治疗中常用的骨水泥材料Biodentine与三氧化矿物凝聚体(mineral trioxide ag-gregrate,MTA)在与血液接触条件下的颜色稳定性,并探讨其可能的变色原因.方法 制备直径5 mm、高3 mm的Biodentine和MTA圆盘,将每种材料的24个圆盘随机分配到去离子水组和脱纤...  相似文献   
67.
In the study the influence of different dental technical tools on the surface temperature and phase composition of fixed dental prostheses (FDPs) made of yttria-partially stabilized zirconia polycrystals (3Y-/4Y-/5Y-PSZ) was investigated. FDPs were fabricated by using computer-aided manufacturing (CAM). The FDPs were treated with a contra-angle handpiece equipped with different burs and polishers. The resulting surface temperatures were measured with a thermographic camera, and the resulting phase transformations were investigated by X-ray diffraction and quantified by Rietveld refinement. Processing with burs resulted in no phase transformation, but a preferred orientation shift. Using coarse polisher induced a phase transformation to the rhombohedral phase, while fine polishers produced no relevant phase transformations and no preferred orientation shift. Compared to the monoclinic phase (ca. 9% theoretical volume increase), which is associated with low-temperature degradation (LTD), the rhombohedral phase is much more voluminous (ca. 15% theoretical volume increase) and distorted and, therefore, has a greater degradation potential.  相似文献   
68.
Extraction of teeth without adequate prosthetic rehabilitation frequently can lead to overeruption of opposing teeth, which may cause occlusal disturbances and complicate dental restoration. Equilibration with consequent need of endodontic treatment, surgical intrusion or extraction are often indicated as a remedy in such cases. The article proposes a method of orthodontic intrusion with the use of temporary anchorage devices as a predictable and less invasive option. Important clinical aspects of molar intrusion with respect to surrounding anatomical structures are also discussed.  相似文献   
69.
Alloplastic and xenogeneic bone grafting materials are frequently used for bone augmentation. The effect of these materials on precursor cells for bone augmentation is yet to be determined. The aim of this study was to ascertain, in vitro, how augmentation materials influence the growth rates and viability of human unrestricted somatic stem cells. The biocompatibility of two xenogeneic and one alloplastic bone graft was tested using human unrestricted somatic stem cells (USSCs). Proliferation, growth, survival and attachment of unrestricted somatic stem cells were monitored after 24 h, 48 h and 7 days. Furthermore, cell shape and morphology were evaluated by SEM. Scaffolds were assessed for their physical properties by Micro-CT imaging. USSCs showed distinct proliferation on the different carriers. Greatest proliferation was observed on the xenogeneic carriers along with improved viability of the cells. Pore sizes of the scaffolds varied significantly, with the xenogeneic materials providing greater pore sizes than the synthetic inorganic material. Unrestricted somatic stem cells in combination with a bovine collagenous bone block seem to be very compatible. A scaffold’s surface morphology, pore size and bioactive characteristics influence the proliferation, attachment and viability of USSCs.  相似文献   
70.
目的 评估Demirjian法测定天津地区儿童的牙龄的适用性.方法 运用Demirjian法测定天津地区替牙早期前牙反合患者治疗期间牙龄的变化量,并与实际年龄的变化量进行比较分析.结果 Demirjian法测定的牙龄变化量无论男性组还是女性组与实际年龄变化量均无显著性差异.结论 Demirjian法适用于中国天津地区替牙前期前牙反合患者牙龄的测定.  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