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   14518篇
  免费   1002篇
  国内免费   49篇
耳鼻咽喉   79篇
儿科学   411篇
妇产科学   396篇
基础医学   1683篇
口腔科学   187篇
临床医学   2277篇
内科学   2976篇
皮肤病学   179篇
神经病学   1394篇
特种医学   250篇
外科学   1343篇
综合类   391篇
一般理论   18篇
预防医学   2022篇
眼科学   261篇
药学   697篇
中国医学   15篇
肿瘤学   990篇
  2023年   72篇
  2022年   35篇
  2021年   238篇
  2020年   153篇
  2019年   243篇
  2018年   286篇
  2017年   222篇
  2016年   230篇
  2015年   294篇
  2014年   433篇
  2013年   702篇
  2012年   984篇
  2011年   1133篇
  2010年   600篇
  2009年   526篇
  2008年   1018篇
  2007年   1063篇
  2006年   1012篇
  2005年   1014篇
  2004年   980篇
  2003年   906篇
  2002年   854篇
  2001年   127篇
  2000年   109篇
  1999年   130篇
  1998年   163篇
  1997年   133篇
  1996年   110篇
  1995年   121篇
  1994年   109篇
  1993年   96篇
  1992年   84篇
  1991年   72篇
  1990年   76篇
  1989年   77篇
  1988年   63篇
  1987年   58篇
  1986年   58篇
  1985年   57篇
  1984年   68篇
  1983年   89篇
  1982年   77篇
  1981年   75篇
  1980年   62篇
  1979年   49篇
  1978年   52篇
  1977年   42篇
  1976年   40篇
  1975年   32篇
  1974年   30篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
2.
3.
Societal concerns about the effects of the COVID-19 pandemic have largely focussed on the social groups most directly affected, such as the elderly and health workers. However, less focus has been placed on understanding the effects on other collectives, such as children. While children’s physical health appears to be less affected than the adult population, their mental health, learning and wellbeing is likely to have been significantly negatively affected during the pandemic due to the varying policy restrictions, such as withdrawal from face to face schooling, limited peer-to-peer interactions and mobility and increased exposure to the digital world amongst other things. Children from vulnerable social backgrounds, and especially girls, will be most negatively affected by the impact of COVID-19, given their different intersecting realities and the power structures already negatively affecting them. To strengthen the understanding of the social determinants of the COVID-19 crisis that unequally influence children’s health and wellbeing, this article presents a conceptual framework that considers the multiple axes of inequalities and power relations. This understanding can then be used to inform analyses and impact assessments, and in turn inform the development of effective and equitable mitigation strategies as well as assist to be better prepared for future pandemics.  相似文献   
4.
BACKGROUND Acute pancreatitis(AP) is a sudden inflammatory process of the pancreas that may also involve surrounding tissues and/or remote organs. Inflammation and parenchymal cell death are common pathological features of this condition and determinants of disease severity. Polyethylene glycols(PEGs) are nonimmunogenic, non-toxic water-soluble polymers widely used in biological, chemical, clinical and pharmaceutical settings.AIM To evaluate the protective effect of a 35-k Da molecular weight PEG(PEG35) on the pancreatic damage associated to cerulein-induced acute pancreatitis in vivo and in vitro.METHODS Wistar rats were assigned at random to a control group, a cerulein–induced AP group and a PEG35 treatment group. AP was induced by five hourly intraperitoneal injections of cerulein(50 μg/kg/bw), while the control animals received saline solution. PEG35 was administered intraperitoneally 10 minutes before each cerulein injection in a dose of 10 mg/kg. After AP induction, samples of pancreatic tissue and blood were collected for analysis. AR42 J pancreatic acinar cells were treated with increasing concentrations of PEG35 prior to exposure with tumor necrosis factor α(TNFα), staurosporine or cerulein. The severity of AP wasdetermined on the basis of plasma levels of lipase, lactate dehydrogenase activity, pancreatic edema and histological changes. To evaluate the extent of the inflammatory response, the gene expression of inflammation-associated markers was determined in the pancreas and in AR42 J-treated cells. Inflammation-induced cell death was also measured in models of in vivo and in vitro pancreatic damage.RESULTS Administration of PEG35 significantly improved pancreatic damage through reduction on lipase levels and tissue edema in cerulein-induced AP rats. The increased associated inflammatory response caused by cerulein administration was attenuated by a decrease in the gene expression of inflammation-related cytokines and inducible nitric oxide synthase enzyme in the pancreas. In contrast, pancreatic tissue m RNA expression of interleukin 10 was markedly increased. PEG35 treatment also protected against inflammation-induced cell death by attenuating lactate dehydrogenase activity and modulating the pancreatic levels of apoptosis regulator protein BCL-2 in cerulein hyperstimulated rats. Furthermore, the activation of pro-inflammatory markers and inflammationinduced cell death in pancreatic acinar cells treated with TNFα, cerulein or staurosporine was significantly reduced by PEG35 treatment, in a dose-dependent manner.CONCLUSION PEG35 ameliorates pancreatic damage in cerulein-induced AP and AR42 J-treated cells through the attenuation of the inflammatory response and associated cell death. PEG35 may be a valuable option in the management of AP.  相似文献   
5.
6.
7.
Journal of Neuro-Oncology - Patients diagnosed with primary central nervous system lymphoma (PCNSL) often face dismal outcomes due to the limited availability of therapeutic options. PCNSL cells...  相似文献   
8.
Identification of high-risk human papillomavirus genotypes causing cervical precancer is crucial for informing HPV vaccine development and efficacy studies, and for determining which types to include in next-generation genotyping assays. Co-occurrence of hrHPV infections is common and complicates carcinogenicity assessment; accurate attribution requires tissue-based genotyping of precancers. We included all women with cervical intraepithelial neoplasia Grade 2 or worse (CIN2+) from the Biopsy Study, an observational study of 690 women enrolled between 2009 and 2012 at the University of Oklahoma. Tissue-based genotyping, including whole tissue sections (WTS) and laser-capture microdissection (LCM), was performed on all precancers with multiple hrHPV infections detected in cytology, totaling over 1,800 HPV genotyping assays. Genotype attribution was compared to hierarchical and proportional hrHPV-type attribution models. Of 276 women with CIN2+, 122 (44.2%) had multiple hrHPV genotypes in cytology. Of 114 women with genotyping data, 94 had one or more hrHPV detected in tissue. Seventy-one women (75.5%) had a single causal hrHPV genotype, while 23 women had multiple hrHPV genotypes causing CIN2+. Ten women had multiple causal infections in a single biopsy, contrary to the previous notion that each lesion is caused by a single type only. While HPV16 was the predominant causal hrHPV genotype using all approaches, the hierarchical model overattributed HPV16, whereas other causal hrHPV genotypes, particularly HPV18 and HPV35, were underattributed. Understanding true causal genotypes is important for the evaluation of vaccine efficacy, to estimate the extent of unmasking, and for type-specific risk assessment in screening and management.  相似文献   
9.
10.

Introduction

INFIX and Pelvic Bridge are two new minimally invasive surgical techniques for unstable pelvic ring injuries, and they have demonstrated early clinical success in small, single-center case-series. The primary objective of this study is to gather evidence speaking to the biomechanical stability of internal bridging methods relative to external fixation, with the expectation of biomechanical equivalence.

Methods

Ten human cadaveric pelvic specimens were dissected free of all skin, fat, organs, and musculature and were prepared with a partially unstable pelvic ring injury (OTA/AO 61-B). The specimens were randomized to two groups and were repaired and tested with anterior pelvic external fixation (APEF) and INFIX sequentially, or APEF and Pelvic Bridge sequentially. Testing was performed with each specimen mounted onto a servo-hydraulic testing frame with axial compression applied to the superior base of the sacrum under five axial loading/unloading sinusoidal cycles between 10?N and 1000?N at 0.1?Hz. Relative translational motion and rotation across the osteotomy site was reported as our primary outcome measures. Outcome measures were further analyzed using a Wilcoxon signed-rank test to determine differences between non-parametric data sets with significance defined as a p value < 0.05.

Results

We found no statistical difference in translation (p?=?0.237, 0.228) or rotation (p?=?0.278, 0.873) at the fracture site when comparing both new constructs to external fixation. Under the imposed loading protocol, no episodes of implant failure or failure at the bone-implant interface occurred.

Discussion

Our study provides the biomechanical foundation necessary to support future clinical trial implementation for pelvic fracture patients. While biomechanical stability of these newer, subcutaneous techniques is equivalent to APEF, the surgeon must take into account their technical abilities and knowledge of pelvic anatomy, patient-specific factors including body habitus, and the potential complications associated with each implant and the ability to avoid them.  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