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   89926篇
  免费   8390篇
  国内免费   6334篇
耳鼻咽喉   715篇
儿科学   940篇
妇产科学   1066篇
基础医学   10983篇
口腔科学   1665篇
临床医学   12348篇
内科学   13523篇
皮肤病学   838篇
神经病学   4910篇
特种医学   3246篇
外国民族医学   61篇
外科学   8840篇
综合类   15163篇
现状与发展   30篇
一般理论   3篇
预防医学   5315篇
眼科学   2597篇
药学   9164篇
  95篇
中国医学   4923篇
肿瘤学   8225篇
  2025年   23篇
  2024年   1205篇
  2023年   2137篇
  2022年   3987篇
  2021年   4789篇
  2020年   3720篇
  2019年   3097篇
  2018年   3157篇
  2017年   2927篇
  2016年   2652篇
  2015年   4157篇
  2014年   4939篇
  2013年   4197篇
  2012年   6329篇
  2011年   7136篇
  2010年   4280篇
  2009年   3262篇
  2008年   4205篇
  2007年   4491篇
  2006年   4420篇
  2005年   4546篇
  2004年   2789篇
  2003年   2547篇
  2002年   2223篇
  2001年   1914篇
  2000年   2152篇
  1999年   2508篇
  1998年   1666篇
  1997年   1589篇
  1996年   1213篇
  1995年   1059篇
  1994年   886篇
  1993年   604篇
  1992年   714篇
  1991年   609篇
  1990年   552篇
  1989年   474篇
  1988年   392篇
  1987年   352篇
  1986年   247篇
  1985年   190篇
  1984年   92篇
  1983年   76篇
  1982年   41篇
  1981年   45篇
  1980年   29篇
  1979年   30篇
  1965年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Functional data analysis, which analyzes data that can be represented by curves or images, has many potential applications in clinical trials. Motivated by a real example, this study constructs a functional mixed effects model for analyzing a clinical outcome that is observed continuously over a long period of time. A penalized spline (P-spline)-based method is applied to obtain the estimators of the mean function and the time-varying coefficients. Simulation studies are conducted to investigate the consistency, efficiency, and robustness of the method. To illustrate the use of the method, a real data analysis is performed and produces interpretable results.  相似文献   
32.
33.
34.
OBJECTIVE: The aims of this study were to investigate the colonisation of Streptococcus mutans and to determine the possibility of horizontal transmission in Chinese nursery children. DESIGN: Fifty-six children aged between 3 and 4 years old from a nursery were included in this study. Twenty-four children were from the day and night nursery class, the others were from the day nursery class. Dental plaque samples were collected with sterile toothpicks and cultured on S. mutans-selective tryptone-yeast-cystine agar supplemented with 0.2U/ml bacitracin and 15% sucrose. The typical isolates of S. mutans were identified by classical microbiological methods and genotyped by arbitrarily primed PCR (AP-PCR) and restriction fragment length polymorphism analysis. RESULTS: S. mutans was isolated from 41 of the 56 children. The prevalence of S. mutans was higher in the children from day nursery class, compared with the children from day and night nursery class (P<0.05). A total of 140 S. mutans isolates from 41 children were analysed by AP-PCR, and 88 different amplitypes were identified. Of 41 children with S. mutans isolates, 82.9% carried two or more genotypes. Two genotypes of S. mutans were repeatedly isolated among 13 children in the day and night nursery class, and one genotype was isolated from two children in the day nursery class. CONCLUSION: The presence of matching genotypes of S. mutans among children attending the same nursery suggests the possibility of horizontal transmission.  相似文献   
35.
目的探讨Simodont虚拟仿真系统中虚拟涡轮机机头的辅助光照对实际操作的影响,为口腔临床技能训练提供指导。 方法选取四川大学华西口腔医学院口腔医学专业本科生56人为研究对象,按随机数表法随机分为两组,实验组(虚拟仿真牙科训练机的涡轮机头的辅助灯处于打开状态)和对照组(虚拟仿真牙科训练机的涡轮机头的辅助灯处于关闭状态)的学生分别使用Simodont虚拟仿真系统在不同辅助光照情况下进行练习和考核,并在临床冷光灯条件下使用玻璃板模拟临床操作,采用t检验对比分析两组的得分。并通过问卷调查了解学生的使用体验。 结果不同辅助光照条件下,Simodont虚拟训练机操作总分(t = 1.342,P = 0.181)和临床冷光灯条件下玻璃板的操作结果(t = -0.585,P = 0.561)差异均无统计学意义;但Simodont总分构成项中"Leeway sides(洞缘偏差)"项有光组学生分数为5.38 ± 4.69,大于无光组分数(4.32 ± 2.92),差异有统计学意义(t = 2.252,P = 0.025)。 结论尚不能认为Simodont系统在有辅助灯的条件下可以影响医学生的培训效果,但在有辅助照明的情况下操作可能更容易误碰到规定区域边界的侧方。问卷结果显示,Simodont虚拟仿真系统是一种值得推广的教学模式。  相似文献   
36.
目的 :总结和评价Branemark种植体支持Nobelpharma杆状种植覆盖义齿的应用经验和效果。方法 :将种植体与Nobelpharma杆卡式附着体结合 ,为13例患者制作种植覆盖义齿 ,随访观察1~4年 ,定期拍X线片了解种植体骨结合情况。结果 :种植体稳固 ,X线片未见种植体周有异常骨吸收 ;患者对义齿的固位力十分满意 ,咀嚼效率和舒适性较原有的传统活动义齿有显著的改善 ,提高患者的生活自信心和生命质量。结论 :Branemark种植体支持Nobelphar ma杆状覆盖义齿稳固、美观、易于维护口腔卫生、手术简单和损伤较小 ,对牙槽嵴严重萎缩者尤为适宜 ;采用两个固位卡即可使种植覆盖义齿获得足够的固位力。  相似文献   
37.

Introduction

This study examined the identity of the microbiome of deep dentinal caries and its correlation with the inflammation status of caries-induced pulpitis.

Methods

Seventy-five cases were diagnosed based on the American Association of Endodontics's diagnostic criteria and divided into 4 groups: normal pulp with deep caries (NP; n = 13), reversible pulpitis with only cold-evoked pain (CRP; n = 17), reversible pulpitis with both cold/heat-evoked pain (CHRP; n = 24), and symptomatic irreversible pulpitis (SIP; n = 21). Samples were sequenced by 16S rDNA. Alpha and beta diversity were determined. Linear discriminant analysis effect size (LEfSe) analysis was used to detect intergroup differences, and receiver operating characteristic (ROC) curves were generated to assess the role of the caries microbiome in caries-induced pulpitis.

Results

The 16S rDNA sequencing yielded 9100 operational taxonomic units. Lactobacillus had the highest relative abundance at the genus level among the 4 groups. There were significant differences in the distribution of the microbiome among the groups. In an alpha diversity analysis, species richness differed between the CRP group and the other groups. In a beta diversity analysis, the distribution of microorganisms in the SIP group was significantly different from those in the other 3 groups. LEfSe analysis indicated substantial differences in the microbiome among the groups, and the areas under the ROC curves (AUC) were all high (AUC: 0.734–0.952).

Conclusions

Characterization of the caries microbiome has the potential to become an auxiliary method for the diagnosis of pulpitis. This finding may prompt new research on diagnostic strategies for caries-induced pulpitis.  相似文献   
38.
This article describes the use of SLS to produce a wax prototype for the fabrication of a partial nasal prosthesis. This technique may be an alternative to more conventional laboratory techniques for facial prosthesis fabrication and allows direct generation of definitive wax patterns. With the satisfying effect of nasal defect restoration, patients may be effectively rehabilitated and derive emotional and physical benefit from the treatment provided.  相似文献   
39.
In the third degree of cleft palate, the palate bones are short, the cleft is wide, the degree of palatal tissue atrophy and the anterior displacement of the muscles are great. It is difficult to repair satisfactorily. We carried out a treatment plan by pushing the soft palate and posterior part of the palatal bone fully back to the physiological closure position by surgical means without cutting through the palatal aponeurosis. By using a palatal plate with pharyngeal prong immediately after operation to fix the composite flap posteriorly and restore the defect of the hard palate. The palatal palate is changed with a silicon obturator or performed secondary operation to repair the perforation of the hard palate after the primary wound is well healed. 24 cases have been performed by this means since 1984. The outcomes are good. It is well conditioned for surgical orthodontics of severe crossbite which results from undeveloped maxilla also.  相似文献   
40.
本文根据作者经治发生于下颌骨的4个恶性血管内皮与外皮瘤病例,结合文献复习,探讨其临床病理特点、诊断治疗与预后等问题。发现该病发生于颌骨者十分罕见,临床易发生误诊,因此,临床医生遇有颌骨肿块生长迅速,疼痛呈持续性且逐渐加重,X线片提示有溶骨性破坏,诊断也应考虑患本病的可能,尽早手术治疗,并于术中行冰冻活检协诊。一般认为本病预后差,但如组织学形态分化较好,治疗及时,切除范围适当,也可获得较佳疗效。  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