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   6756篇
  免费   709篇
  国内免费   7篇
耳鼻咽喉   174篇
儿科学   424篇
妇产科学   251篇
基础医学   608篇
口腔科学   584篇
临床医学   678篇
内科学   1315篇
皮肤病学   175篇
神经病学   491篇
特种医学   270篇
外科学   1432篇
综合类   32篇
一般理论   1篇
预防医学   265篇
眼科学   179篇
药学   347篇
中国医学   9篇
肿瘤学   237篇
  2024年   12篇
  2023年   140篇
  2022年   87篇
  2021年   221篇
  2020年   183篇
  2019年   227篇
  2018年   424篇
  2017年   334篇
  2016年   414篇
  2015年   406篇
  2014年   431篇
  2013年   830篇
  2012年   362篇
  2011年   371篇
  2010年   421篇
  2009年   228篇
  2008年   153篇
  2007年   76篇
  2006年   207篇
  2005年   150篇
  2004年   68篇
  2003年   62篇
  2002年   82篇
  2001年   142篇
  2000年   112篇
  1999年   134篇
  1998年   139篇
  1997年   103篇
  1996年   131篇
  1995年   85篇
  1994年   93篇
  1993年   80篇
  1992年   57篇
  1991年   59篇
  1990年   43篇
  1989年   26篇
  1988年   33篇
  1987年   15篇
  1986年   23篇
  1985年   21篇
  1984年   27篇
  1983年   21篇
  1982年   25篇
  1981年   26篇
  1980年   22篇
  1979年   17篇
  1978年   8篇
  1977年   9篇
  1976年   11篇
  1974年   8篇
排序方式: 共有7472条查询结果,搜索用时 15 毫秒
991.
992.

Background

Genetic polymorphisms of the renin-angiotensin system (RAS) have been reported to play an important role in the pathogenesis of diabetes mellitus and hypertension. In addition, a close association has been reported between RAS and the progression of both diabetes and hypertension. But the role of RAS on the development of posttransplantation diabetes mellitus (PTDM) is not known. For this purpose we investigated the association of polymorphisms in the genes for angiotensin-converting enzyme (ACE) and angiotensinogen (AGT) with the development of PTDM.

Methods

Genotyping for ACE insertion/deletion (I/D) and AGT M235T polymorphisms was performed in 50 patients who underwent renal transplantation during a 5-year period. Group 1 consisted of 23 recipients who developed PTDM and group 2 consisted of 27 recipients that did not have PTDM.

Results

Of 50 patients, 13 (26%) showed the ACE DD, 21 (42%) the ACE ID, and 16 the ACE II genotype. The frequencies of AGT MM, AGT MT, and AGT TT were 0, 54%, and 46%, respectively. Compared with group 2, there were high frequencies of the AGT TT genotype in group 1 recipients (P < .001). In addition the ACE DD genotype was found significantly higher in group 1 patients compared with group 2 patients (P = .001).

Conclusion

The high frequencies of the AGT TT genotype and ACE DD genotype in recipients may contribute to the high prevalence of PTDM. Our data suggest a synergistic effect between the ACE and AGT polymorphism in the risk of PTDM, but to support this theory a larger patient group must be studied.  相似文献   
993.
Rapamycin (RPM) has antiangiogenic and antiproliferative effects on cells. The aim of this study was to evaluate the mechanism of RPM as a novel antifibrotic agent by assessing its effect on interstitial fibrosis (IF). Among 60 renal transplant recipients, group 1 patients (n = 20) were treated with RPM and group 2 (n = 40), with cyclosporine. The proportions of infiltrating macrophages and lymphocytes in the interstitium were evaluated in 1-year biopsies. The microvessels were highlightened with CD34. After an initial biopsy, the development of diffuse IF over 18 months was evaluated by follow-up biopsies. The mean microvessel density (MVD) was significantly lower among group 1 (69.3 ± 16) versus group 2 (96.5 ± 30; P < .001). The proportions of macrophages and lymphocytes were lower in group 1 compared to group 2 biopsies (P < .001 for both). Fourteen (35%) group 2 and only 2 (10%) group 1 cases developed IF over 18 months (P < .05). The mean MVD in the initial biopsy was 75.6 ± 18 in cases that did not versus 120 ± 28 among those who did develop IF (P < .001). The amount of interstitial inflammation was greater among patients who did compared with cases who did not develop IF (P < .01). The overall 1-, 3-, and 5-year graft survival rates for group 1 were 95%, 95%, and 89% versus 95%, 65%, and 45% for group 2 patients, respectively (P < .001). RPM-treated patients showed a lower incidence of diffuse IF, which can be explained by antiproliferative and antiangiogenic effects of RPM. In conclusion, RPM therapy displayed an independently positive impact on long-term graft survival.  相似文献   
994.
Zou  Ding  Wennman  Heini  Ekblom  Örjan  Grote  Ludger  Arvidsson  Daniel  Blomberg  Anders  Torén  Kjell  Bergström  Göran  Börjesson  Mats  Hedner  Jan 《Sleep & breathing》2019,23(1):319-326
Sleep and Breathing - The relationship between insomnia and cardiorespiratory fitness (CRF), a well-established risk factor for cardiovascular disease, has not been extensively studied. We aimed to...  相似文献   
995.

Aim

The aim of this study was to compare conventional radiography, storage phosphor plate, and cone beam computed tomography for in vitro determination of occlusal and approximal caries.

Methods

A total of 72 extracted human premolar and molar teeth were selected. Teeth were radiographed with conventional intraoral radiography, a storage phosphor plate system, and cone beam computed tomography and evaluated by two observers. The teeth were then separated and examined with a stereomicroscope and a scanner at approximately 8× magnification.

Results

CBCT was statistically superior to conventional radiography and phosphor plate for determining occlusal caries. No significant difference from CBCT, conventional radiography and the phosphor plate system for determining approximal caries was found.

Conclusion

The CBCT system may be used as an auxiliary method for the detection of caries.  相似文献   
996.
This article presents a case with nevoid basal cell carcinoma syndrome (NBCCS) and an elongated styloid process. Basal cell carcinoma syndrome, also known as Gorlin-Goltz syndrome, is an autosomal dominant inherited syndrome manifested by multiple defects involving the skin, nervous system, eyes, endocrine system, and bones. Elongated styloid process or calcified stylohyoid ligament cause craniofacial or cervical pain. The actual cause of elongation of the styloid process or the calcification of the stylohyoid ligament is unclear. The cause of elongation of styloid process in this case may be the calcification induced by NBCCS. This report is the first case presentation of NBCCS with elongated styloid process. Elongated styloid process might be described as an anomaly of an NBCCS.  相似文献   
997.
Langerhans cell histiocytosis is a collective term used to describe a group of enigmatic proliferative disorders. Three disease variants include eosinophilic granuloma, Letterer-Siwe disease, and Hand-Schuller-Christian syndrome. Eosinophilic granuloma is reported to be the most benign type of the triad. In this report, a 7-year-old child with an eosinophilic granuloma of the left side of her mandible is presented. There was a painless, hard, tender mass arising from the left side of the molar region. Panoramic radiographs showed a radiolucent area at the molar region. The lesion was resolved 2 weeks after the biopsy. The 1.5 years of radiographic and clinical follow-up was satisfactory.  相似文献   
998.
999.
1000.
This study investigated the effect of surface treatments on the retentive strength of zirconia posts and cores to root canals. Maxillary central incisors (n = 40) were treated endodontically, obturated, and post spaces were prepared. Zirconia posts and cores (n = 40) were obtained and assigned randomly to four groups (n = 10 per group; control, sandblasting, tribochemical silica coating, and tribochemical silica coating + silanization). Posts were cemented adhesively, and tensile force was applied. All treatment methods increased the tensile strength of zirconia posts and cores compared to the control group (P = .034). No significant difference was found between treatment methods. Failure types varied depending on the surface treatment method.  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