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   5641篇
  免费   327篇
  国内免费   37篇
耳鼻咽喉   65篇
儿科学   127篇
妇产科学   280篇
基础医学   656篇
口腔科学   145篇
临床医学   438篇
内科学   1204篇
皮肤病学   69篇
神经病学   319篇
特种医学   203篇
外国民族医学   4篇
外科学   984篇
综合类   100篇
一般理论   3篇
预防医学   375篇
眼科学   276篇
药学   381篇
中国医学   11篇
肿瘤学   365篇
  2023年   46篇
  2022年   133篇
  2021年   251篇
  2020年   135篇
  2019年   192篇
  2018年   262篇
  2017年   193篇
  2016年   166篇
  2015年   165篇
  2014年   259篇
  2013年   306篇
  2012年   414篇
  2011年   439篇
  2010年   259篇
  2009年   201篇
  2008年   301篇
  2007年   293篇
  2006年   250篇
  2005年   255篇
  2004年   211篇
  2003年   209篇
  2002年   180篇
  2001年   75篇
  2000年   75篇
  1999年   57篇
  1998年   27篇
  1997年   22篇
  1996年   33篇
  1995年   28篇
  1994年   19篇
  1993年   17篇
  1992年   58篇
  1991年   53篇
  1990年   51篇
  1989年   49篇
  1988年   29篇
  1987年   29篇
  1986年   34篇
  1985年   30篇
  1984年   24篇
  1983年   16篇
  1982年   14篇
  1981年   9篇
  1979年   21篇
  1978年   11篇
  1976年   10篇
  1974年   10篇
  1973年   11篇
  1971年   10篇
  1970年   9篇
排序方式: 共有6005条查询结果,搜索用时 15 毫秒
81.
82.
83.
Visceral basidiobolomycosis is an unusual fungal infection of viscera caused by saprophyte Basidiobolus ranarum. It is very rare in healthy children and poses a diagnostic challenge due to the non-specific clinical presentation and the absence of predisposing factors. We report a case of gastrointestinal basidiobolomycosis in a 4-year-old healthy girl who presented with a short history of abdominal pain, bleeding per rectum, fever, and weight loss. The diagnosis was based on high eosinophilic count, classical histopathology findings of fungal hyphae (the Splendore-Hoeppli phenomenon), and positive fungal culture from a tissue biopsy. Fungal infection was successfully eradicated with a combined approach of surgical resection of the infected tissue and a well-monitored course of antifungal therapy. The atypical clinical presentation, diagnostic techniques, and the role of surgery in the management of a rare and lethal fungal disease in an immunocompetent child are discussed.Key words: Basidiobolomycosis, child, fungal infection, gastrointestinal, immunocompetent  相似文献   
84.
A prenatally diagnosed fetus with hypoplastic left heart syndrome and intact atrial septum was delivered in the cardiac catheterization suite. Using radio frequency energy, a transseptal perforation of the thickened and intact atrial septum was immediately performed following transcatheter cannulation of the right atrium via the umbilical vein. Serial cutting balloon septostomies followed by static balloon septostomies resulted in effective left atrial decompression, atrial mixing, and optimal pulmonary and systemic perfusion. The child is now thriving after both stage I Norwood and bidirectional Glenn procedures.  相似文献   
85.
CASE: A 40-year-old female presented with primary amenorrhoea at 17 years of age. She was tall at 98th centile for height with eunuchoidal body habitus. Her breast development was Tanner stage 3, pubic and axillary hair Tanner stage 4 with normal external genitalia. Her bone age was 13.4 years at a chronological age of 17.8 years. Gonadotrophins were elevated indicating primary ovarian failure. A diagnostic laparotomy revealed hypoplastic, infantile uterus with bilateral streak gonads. Chromosomal analysis showed a balanced reciprocal translocation 46X, t(X; 2) (q22 p13). She became pregnant by in vitro fertilization with egg donation at the age of 36 years. At 13 weeks of gestation, she presented with intractable vomiting. She had raised corrected serum calcium and parathyroid hormone concentrations consistent with the diagnosis of primary hyperparathyroidism (PHPT). She underwent parathyroidectomy at 24 weeks of gestation with removal of a large left inferior parathyroid adenoma which normalized her serum calcium. Multipoint linkage from a genome-wide screen has identified a region of suggestive linkage on chromosome 2p13.3-14 in some cases of familial isolated hyperparathyroidism (FIHP). CONCLUSION: To our knowledge, this is the first case of primary amenorrhoea due to reciprocal translocation involving chromosome 2 and the X chromosome associated with PHPT. PHPT in this case is most likely to be as a result of chromosome 2 involvement where a locus for FIHP has been identified. Identification of the gene involved on chromosome 2p13.3-14 will be of considerable interest.  相似文献   
86.
Introduction: Prevalence of pulmonary hypertension (PH) and its influence on survival in chronic obstructive pulmonary disease (COPD) are not well studied in the lung allocation score (LAS) era.

Methods: The UNOS database was queried from 2005 to 2013 to identify first-time adult lung transplant candidates with COPD who were tracked from wait list entry date until death or censoring to determine both prevalence and influence of PH. Using right heart catheterization measurements, mild PH was defined as mean pulmonary artery pressure (mPAP) ≥ 25 mmHg and severe ≥ 35 mmHg.

Results: Of 1315 COPD candidates not transplanted, 1243 were used for survival analysis using Cox proportional hazards models, and 1010 (mild PH) and 244 (severe PH) were used for propensity score matching, respectively. A total of 52% (652) of subjects had PH mPAP ≥ 25 mmHg. Univariate analysis revealed significant differences in survival for mild PH (HR = 1.769; 95% CI: 1.331, 2.351; p < 0.001) and severe PH (HR = 3.271; 95% CI: 2.311, 4.630; p < 0.001). Kaplan–Meier survival function demonstrated significant disparities for mild PH (Log-rank test: Chi-square1: 15.87, p < 0.0001) and severe PH (Log-rank test: Chi-square1: 50.13, p < 0.0001). Multivariate Cox models identified significant risk for death for mild PH (HR = 1.987; 95% CI: 1.484, 2.662; p < 0.001) and severe PH (HR = 3.432; 95% CI: 2.410, 4.888; p < 0.001). Propensity score matching confirmed increased mortality hazard associated with mild PH (HR = 2.280; 95% CI: 1.425, 3.649; p = 0.001) and severe PH (HR = 7.000; 95% CI: 2.455, 19.957; p < 0.001).

Conclusions: PH is highly prevalent in advanced COPD and associated with a significantly higher risk for mortality.  相似文献   
87.
88.
Objective:To evaluate the effect of a light-emitting diode (LED) and/or low-level laser (LLL) with or without the use of anterior bite jumping appliances (also known as functional appliances [FAs]) on mandibular growth in rats.Materials and Methods:Thirty-six 8-week-old male Sprague-Dawley rats weighing 200 g were obtained from Charles River Canada (St. Constant, QC, Canada) and were divided into six groups of six animals each. Groups were as follows: group 1: LLL; group 2: LLL + FA; group 3: LED; group 4: LED + FA; group 5: FA; and group 6: control (no treatment). Mandibular growth was evaluated by histomorphometric and micro computed tomographic (microCT) analyses.Results:The LED and LED + FA groups showed an increase in all condylar tissue parameters compared with other groups.Conclusion:The LED-treated groups showed more mandibular growth stimulation compared with the laser groups.  相似文献   
89.
90.

Objective

This study aimed to evaluate stress patterns generated within implant-supported mandibular overdentures retained by two different attachment types: ball and socket and locator attachments.

Materials and methods

Commercial CAD/CAM and finite element analysis software packages were utilized to construct two 3D finite element models for the two attachment types. Unilateral masticatory compressive loads of 50, 100, and 150 N were applied vertically to the overdentures, parallel to the longitudinal axes of the implants. Loads were directed toward the central fossa in the molar region of each overdenture, that linear static analysis was carried out to find the generated stresses and deformation on each part of the studied model.

Results

According to FEA results the ball attachment neck is highly stressed in comparison to the locator one. On the other hand mucosa and cortical bone received less stresses under ball and socket attachment.

Conclusions

Locator and ball and socket attachments induce equivalent stresses on bone surrounding implants. Locator attachment performance was superior to that of the ball and socket attachment in the implants, nylon caps, and overdenture. Locator attachments are highly recommended and can increase the interval between successive maintenance sessions.  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