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   5475篇
  免费   377篇
  国内免费   180篇
耳鼻咽喉   19篇
儿科学   28篇
妇产科学   5篇
基础医学   297篇
口腔科学   2169篇
临床医学   116篇
内科学   196篇
皮肤病学   257篇
神经病学   97篇
特种医学   82篇
外科学   465篇
综合类   808篇
预防医学   121篇
眼科学   14篇
药学   643篇
中国医学   684篇
肿瘤学   31篇
  2024年   20篇
  2023年   112篇
  2022年   101篇
  2021年   198篇
  2020年   133篇
  2019年   156篇
  2018年   127篇
  2017年   142篇
  2016年   163篇
  2015年   194篇
  2014年   343篇
  2013年   397篇
  2012年   368篇
  2011年   424篇
  2010年   306篇
  2009年   259篇
  2008年   308篇
  2007年   288篇
  2006年   285篇
  2005年   205篇
  2004年   201篇
  2003年   172篇
  2002年   152篇
  2001年   125篇
  2000年   94篇
  1999年   91篇
  1998年   86篇
  1997年   73篇
  1996年   55篇
  1995年   52篇
  1994年   52篇
  1993年   41篇
  1992年   40篇
  1991年   40篇
  1990年   31篇
  1989年   33篇
  1988年   21篇
  1987年   23篇
  1986年   21篇
  1985年   17篇
  1984年   17篇
  1983年   10篇
  1982年   8篇
  1981年   5篇
  1980年   11篇
  1979年   9篇
  1978年   11篇
  1977年   4篇
  1975年   2篇
  1974年   3篇
排序方式: 共有6032条查询结果,搜索用时 98 毫秒
1.
《Dental materials》2020,36(1):119-134
ObjectiveThe aim of this systematic review and meta-analysis was to evaluate the effect of surface conditioning methods on the bond strength of industrial indirect composite blocks (ICs).MethodsBased on the PICOS strategy, the Medline via PubMed, Embase and Web of Science (ISI – Web of Knowledge) electronic databases were searched for peer-reviewed articles in both English and Chinese, with no publication year limit. In vitro studies evaluating the effects of surface conditioning on the bond strength of ICs were selected. The meta-analysis was conducted to calculate the mean difference between surface-conditioned ICs and unconditioned controls. Subgroup analysis was performed to evaluate the different surface conditioning methods, separately for polymer-infiltrated ceramic network (PICN) material and the ICs with dispersed fillers (ICDFs). Meta-analyses were performed with a random-effects model at a significance level of 0.05.Results and SignificanceFrom 802 relevant studies, 25 were selected for full-text analysis. Nineteen studies were eligible for inclusion in this systematic review, whereas 9 studies were included in the meta-analysis. A manual search of the principal periodicals specific to the area resulted in no additional articles. The meta-analysis indicated a significant difference in bond strength between the surface-conditioned ICs and controls under both non-aged and aged conditions. The combination of mechanical and chemical conditioning yielded the highest bond strength of ICs. This meta-analysis suggests that chemical etching followed by a universal primer and alumina air abrasion followed by a silane coupling agent could be considered the best strategy for optimizing the bond strength of PICN materials and ICDFs under aged conditions, respectively.  相似文献   
2.
While decreasing trend in gender differences in alcohol use disorders was reported in Western countries, the change in Asian countries is unknown. This study aims to explore the shifts in gender difference in alcohol abuse (AA) and dependence (AD) in Korea. We compared the data from two nation-wide community surveys to evaluate gender differences in lifetime AA and AD by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Face-to-face interviews using the Composite International Diagnostic Interview (CIDI) were applied to all subjects in 2001 (n=6,220) and 2011 (n=6,022). Male-to-female ratio of odds was decreased from 6.41 (95% CI, 4.81-8.54) to 4.37 (95% CI, 3.35-5.71) for AA and from 3.75 (95% CI, 2.96-4.75) to 2.40 (95% CI, 1.80-3.19) for AD. Among those aged 18-29, gender gap even became statistically insignificant for AA (OR, 1.59; 95% CI, 0.97-2.63) and AD (OR, 1.18; 95% CI, 0.80-2.41) in 2011. Men generally showed decreased odds for AD (0.55; 95% CI, 0.45-0.67) and women aged 30-39 showed increased odds for AA (2.13; 95% CI 1.18-3.84) in 2011 compared to 2001. Decreased AD in men and increased AA in women seem to contribute to the decrease of gender gap. Increased risk for AA in young women suggests needs for interventions.  相似文献   
3.
4.
大孔吸附树脂分离纯化何首乌有效成分二苯乙烯苷的研究   总被引:2,自引:0,他引:2  
目的研究不同型号大孔吸附树脂纯化何首乌中二苯乙烯苷的工艺条件及参数。方法以静态饱和吸附量、洗脱量、静态洗脱率为考察指标,比较了7种大孔树脂,并对HPD500树脂的动态比上柱量、比吸附量、比洗脱量进行了考察,以二苯乙烯苷转移率和纯度为指标对树脂吸附工艺条件进行了筛选。结果所比较的7种树脂中,HPD500型树脂具有最佳的吸附及洗脱参数,其动态饱和吸附量达到151.7mg·g-1干树脂,其最佳工艺为以6倍柱体积去离子水、4倍柱体积10%乙醇、6倍柱体积60%乙醇依次洗脱,二苯乙烯苷转移率为95%,其纯度为75.3%。结论HPD500树脂吸附性能较好,适合于何首乌中二苯乙烯苷的纯化。  相似文献   
5.
异体甘油保存皮与自体微粒皮复合移植的临床应用   总被引:1,自引:0,他引:1  
目的:寻找深度大面积\烧伤的早期治疗方法。方法:大面积深度烧伤于4-5天即行切痂,以异体甘油皮为支架,将有限的自体皮制作成微粒皮后均匀地复合植于创面。结果:对5例共12个肢体2个躯干进行早期切痂后异体甘油皮+自体微粒皮的复合移植,成活后的创面平堤,外观平整,颜色淡红或近拟正常皮肤,触饮,收缩少,结论:异体甘油保存皮+自体微粒皮复合移植是大面积深度烧伤较理想的治疗方法。  相似文献   
6.
7.
碳纤维根管桩的研制   总被引:1,自引:0,他引:1  
目的研究高强度碳纤维增强复合树脂根管桩的加工成型工艺.方法用湿法制备碳纤维预浸料,在预成型模具中预成型,然后在成型模具中经特殊的工艺进行成型,最后用车床加工成预定形状的桩钉;并测试其弯曲强度、剪切强度和碳纤维含量.结果随着碳纤维含量的增加,根管桩的弯曲强度和剪切强度均逐渐增加.碳纤维含量达到67.13%时,弯曲强度和剪切强度分别达到406MPa和653.86MPa.结论高强度的碳纤维根管桩可以满足临床需要.  相似文献   
8.
嵌体与全冠治疗牙间食物嵌塞的临床应用比较   总被引:3,自引:0,他引:3  
目的:比较嵌体与全冠治疗牙间食物嵌塞的临床操作及修复效果.方法:对纳入标准的78例患者随机分组,分别用嵌体和全冠进行修复并进行随访观察,并对两种方法的临床应用效果进行比较.结果:在对牙龈及牙周保护方面,嵌体与全冠有显著性差异;在边缘密合、重塑邻接关系及牙齿敏感方面,二者无显著性差异.结论:嵌体较全冠修复牙间食物嵌塞临床操作简便省时,更有利于保护牙髓及牙周组织健康,美观经济.  相似文献   
9.
目的探讨复方丹参注射液联合干扰素治疗慢性乙肝患者的疗效。方法110例慢性乙肝患者,按随机方法分成①对照组30例,应用普通保肝药物治疗,疗程6个月;②丹参组30例,应用复方丹参注射液(每ml含丹参、降香各1g)30ml加入10%葡萄糖溶液300ml中静脉注射1个月;③IFN组30例,应用IFN—α 3MU,隔日一次肌内注射,3个月;④联合组20例,应用复方丹参注射液30ml加10%葡萄糖溶液300ml静脉注射1个月,IFN-α 3MU,隔日一次肌内注射,3个月。丹参组,IFN组和联合组保肝药物治疗同对照组。四组病例在性别、年龄、病程,治疗前肝功能等方面均无统计学差异。治疗前检测肝功能,肝炎病毒标志,血清HA、IV—C、PCI—Ⅱ,部分病例进行肝穿病理检查。治疗开始后每月检测肝功能,3个月(治疗后)和6个月(随访时)时检测血清HA、IV—C、PCⅢ及乙肝病毒标志,治疗后1年行肝穿病理检查。结果治疗前四组患者血清HA、PCⅢ、IV—C水平无统计学差异;治疗后丹参组、IFN组、联合组血清HA、FCⅢ、IV—C水平较治疗前及对照组有不同程度的降低。结论复方丹参注射液联合IFN治疗可使血清HA、PCⅢ、IV—C有明显下降,肝组织病理改变明显改善,为目前有效的慢性乙肝治疗措施。  相似文献   
10.
OBJECTIVE: Tubularized incised plate urethroplasty has become a popular technique for repairing distal and proximal hypospadias in many institutions. Dorsal inlay graft urethroplasty has been used in our institution since 2003 to reduce the risk of meatal stenosis. In the present study, we evaluated the results of the dorsal inlay graft procedure. METHODS: A total of 28 patients with no deep groove and no severe curvature underwent one-stage urethroplasty using an inner preputial-based dorsal inlay graft. The medical records of all patients were retrospectively reviewed with regard to complication rate and cosmetic appearance. RESULTS: Mean patient age at surgery was 21 months (range, 14 months to 4.6 years). Preoperatively the urethral meatus was coronal in two cases, distal shaft in 17, proximal shaft in six and penoscrotal in three. Nine patients required testosterone therapy before surgery. Mean operative time was 200 min (range, 154-249 min). Mean length of inlay graft was 20.9 mm (range, 12-30 mm). In all patients, a straight penis was achieved without dorsal plication of the corposa cavernosa, and the neomeatus with a slit-like appearance was positioned at the glans tip. At a mean of 22 months of follow up, a urethrocutaneous fistula developed in only one patient (3.6%), requiring repair surgery 6 months after urethroplasty. No patient had meatal stenosis, neourethral stricture or urethral diverticulum along the inlay graft. CONCLUSION: Dorsal inlay graft urethroplasty is an effective method for hypospadiac repair and leads to good cosmetic outcome with low risk of complications.  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