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   385篇
  免费   23篇
  国内免费   2篇
耳鼻咽喉   1篇
儿科学   17篇
妇产科学   8篇
基础医学   44篇
口腔科学   48篇
临床医学   34篇
内科学   47篇
皮肤病学   2篇
神经病学   22篇
特种医学   15篇
外科学   39篇
综合类   17篇
预防医学   43篇
眼科学   20篇
药学   17篇
中国医学   2篇
肿瘤学   34篇
  2024年   1篇
  2023年   6篇
  2022年   10篇
  2021年   20篇
  2020年   11篇
  2019年   15篇
  2018年   21篇
  2017年   18篇
  2016年   7篇
  2015年   15篇
  2014年   18篇
  2013年   16篇
  2012年   31篇
  2011年   35篇
  2010年   12篇
  2009年   13篇
  2008年   24篇
  2007年   20篇
  2006年   22篇
  2005年   12篇
  2004年   12篇
  2003年   5篇
  2002年   9篇
  2001年   5篇
  2000年   6篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1992年   3篇
  1991年   7篇
  1990年   4篇
  1989年   6篇
  1988年   2篇
  1987年   4篇
  1986年   2篇
  1985年   3篇
  1984年   4篇
  1983年   1篇
  1982年   1篇
  1979年   2篇
  1975年   1篇
排序方式: 共有410条查询结果,搜索用时 31 毫秒
31.
32.
The selective use of prenatal screening by Bedouin women attending Ministry of Health, maternal and child health clinics in Israel is examined. The data consist of a review of 537 prenatal care records, 16 in depth interviews with mothers, and four interviews with health personnel. These data are part of a larger study that took place between 1994-99 amongst Negev Bedouin women, part of the Palestinian Arab minority within Israel. The record review shows that the majority of women who attend prenatal care do not take up referrals for Maternal Serum Alpha Feto Protein (MSAFP) testing or for amniocentesis tests. Although many women interviewed talked about the value of prenatal screening, they also spoke of 'false alarms' that may result from testing. Similarly, women were aware that the socially preferred pattern of consanguinity in marriage amongst the Bedouin may cause medical problems, however test uptake was unrelated to consanguinity. There was a variety of views concerning the permissibility of terminating a pregnancy. This study shows that women use prenatal screening selectively in a way that helps them to balance social and medical risk.  相似文献   
33.
34.
35.
OBJECTIVES: The aim of this prospective study was to document, radiographically, changes in the apical bone levels on microthreaded implants placed in subsinus residual bone height, according to a bone-added osteotome sinus floor elevation technique with platelet-rich fibrin (PRF) as grafting material. STUDY DESIGN: Implants were placed using PRF as grafting material in the bone-added osteotome sinus floor elevation (BAOSFE) technique. The survival rate at abutment tightening (6 to 12 weeks of healing) and at 1 year was calculated. The radiographic analysis determined on consecutive radiographs: 1) the mean residual bone height (RBH) under the maxillary sinus at implant placement; and 2) the change in endosinus bone level. Mean and standard deviation were used to assess the endosinus bone changes in the mesial and distal implant sides at 1 year. RESULTS: Between December 2004 and June 2005, 20 consecutive patients were included in the study after bone height measurement by periapical radiographs. Patients included 14 women (70%) and 6 men (30%) with a mean age of 54.8 +/- 11.1 years, range 35 to 73 years; they were treated with 35 Astra Tech implants (Astra Tech Dental Implant System; Astra Tech, M?lndal, Sweden) fulfilling the inclusion criteria. The mean healing time before abutment tightening was 8.3 +/- 1.4 weeks (range 6-12 weeks); by this time, 1 implant was mobile and was removed. At 1 year, all implants were clinically stable and the definitive prostheses were in function, resulting in a survival rate of 97.1%. Nineteen implants (55%) were 11 mm long, 6 implants (17%) were 9 mm, 5 implants (14%) were 8 mm, and 5 implants (14%) were 13 mm. The RBH was measured after implant placement on the radiographs on both implant sides. The mean RBH was 6.5 +/- 1.7 mm: 6.3 +/- 1.3 on the mesial side and 6.7 +/- 2.0 mm on the distal side. Measurements of the changes in the endosinus level on the mesial and distal sides showed that all implants gained endosinus bone. The mean endosinus gain was 3.2 +/- 1.5 mm: 3.5 +/- 1.4 mm on the mesial side and 2.9 +/- 1.6 mm on the distal side. The lowest bone gain was 0.9 mm and 0.1 mm on the mesial and distal sides, respectively. The highest gain was 5.8 mm and 5.2 mm on the mesial and distal sides, respectively. CONCLUSIONS: The BAOSFE procedure with PRF as grafting material can lead to an endosinus bone gain. Despite a limited RBH, a healing period of 2-3 months was found to be sufficient to resist a torque of 25 N.cm applied during abutment tightening. At 1 year, formation of a new recognizable bone structure delimiting the sinus floor was identified radiologically and led to a predictable implant function.  相似文献   
36.
37.
38.
39.
Programmed death ligand-1 (PD-L1) plays a critical role in T-cell regulatory function. Here, we report a newly discovered effect of PD-L1 on angiogenesis. We demonstrate that PD-L1 and its receptor CD80, but not PD-1, are expressed by primary murine lung and heart vascular endothelial cells and the miscrovascular endothelial cell line (MS1) at both the mRNA and protein levels in vitro. The inhibition of PD-L1 or CD80 expression in MS1 cells, by small-interfering RNA transfection, led to a significant up-regulation of vascular endothelial growth factor receptor 2 expression and cell proliferation levels in MS1 cells. Furthermore, MS1 cells were found to have a significantly lower proliferation and vascular endothelial growth factor receptor 2 expression levels when they were co-cultured with PD-L1-expressing normal corneal epithelial cells, as compared to MS1 cells co-cultured with PD-L1(-/-) corneal epithelial cells. In a suture-induced corneal angiogenesis model, we observed a significantly higher level of angiogenic response in PD-L1(-/-) knockout mice as compared to wild-type mice, although there was no significant difference in the expression of inflammatory cytokines (interleukin-1α, interleukin-1β, or tumor necrosis factor-α) or the infiltration of innate immune cells (neutrophils and macrophages) between the two groups. We conclude that the expression of PD-L1 in both vascular endothelial cells and corneal epithelial cells regulates corneal angiogenesis.  相似文献   
40.
INTRODUCTION AND OBJECTIVES: Brain tumorigenesis is a complex process involving multiple genetic alterations. Cyclin D1 and BAX genes are two of the most important regulators in controlling the normal proliferation and apoptosis of cells, respectively. In this study, we analysed the possibilities of involvement of cyclin D1 and BAX genes in the gliomagenesis. METHODS AND RESULTS: In determining gene alterations of exon 4 of cyclin D1 gene and exon 6 of BAX gene, all samples were amplified by polymerase chain reaction (PCR) and subsequently by direct sequencing. Our results showed a frameshift mutation (G base deletion) at nucleotide 82 of codon 28 in exon 4 of the cyclin D1 gene and another frameshift mutation with a deletion of C base at nucleotide 153 of exon 6 of the BAX gene in two separate cases of a glioblastoma multiform (WHO Grade IV) sample. CONCLUSION: These findings suggest that both cyclin D1 and BAX genes alteration are rarely found in brain tumors. However, the alteration might cause a significant effect of the normal protein production and this might contribute to the development of brain tumorigenesis in Malaysian patients.  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