全文获取类型
收费全文 | 2085篇 |
免费 | 98篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 39篇 |
妇产科学 | 82篇 |
基础医学 | 362篇 |
口腔科学 | 14篇 |
临床医学 | 204篇 |
内科学 | 402篇 |
皮肤病学 | 19篇 |
神经病学 | 201篇 |
特种医学 | 80篇 |
外科学 | 362篇 |
综合类 | 8篇 |
预防医学 | 109篇 |
眼科学 | 45篇 |
药学 | 113篇 |
中国医学 | 19篇 |
肿瘤学 | 107篇 |
出版年
2022年 | 19篇 |
2021年 | 49篇 |
2020年 | 24篇 |
2019年 | 36篇 |
2018年 | 52篇 |
2017年 | 33篇 |
2016年 | 26篇 |
2015年 | 59篇 |
2014年 | 60篇 |
2013年 | 73篇 |
2012年 | 121篇 |
2011年 | 125篇 |
2010年 | 49篇 |
2009年 | 47篇 |
2008年 | 98篇 |
2007年 | 103篇 |
2006年 | 116篇 |
2005年 | 112篇 |
2004年 | 105篇 |
2003年 | 103篇 |
2002年 | 99篇 |
2001年 | 47篇 |
2000年 | 48篇 |
1999年 | 39篇 |
1998年 | 20篇 |
1997年 | 14篇 |
1996年 | 16篇 |
1995年 | 18篇 |
1992年 | 28篇 |
1991年 | 38篇 |
1990年 | 27篇 |
1989年 | 32篇 |
1988年 | 35篇 |
1987年 | 35篇 |
1986年 | 21篇 |
1985年 | 37篇 |
1984年 | 21篇 |
1983年 | 24篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 31篇 |
1977年 | 8篇 |
1975年 | 7篇 |
1974年 | 11篇 |
1973年 | 8篇 |
1972年 | 14篇 |
1970年 | 8篇 |
1969年 | 9篇 |
1968年 | 9篇 |
排序方式: 共有2195条查询结果,搜索用时 0 毫秒
31.
32.
33.
34.
Danuta M. Bukowska Avenell L. Chew Emily Huynh Irwin Kashani Sue Ling Wan Pak Ming Wan Fred K Chen 《Biomedical optics express》2015,6(12):4676-4693
A large number of human retinal diseases are characterized by a progressive loss of cones, the photoreceptors critical for visual acuity and color perception. Adaptive Optics (AO) imaging presents a potential method to study these cells in vivo. However, AO imaging in ophthalmology is a relatively new phenomenon and quantitative analysis of these images remains difficult and tedious using manual methods. This paper illustrates a novel semi-automated quantitative technique enabling registration of AO images to macular landmarks, cone counting and its radius quantification at specified distances from the foveal center. The new cone counting approach employs the circle Hough transform (cHT) and is compared to automated counting methods, as well as arbitrated manual cone identification. We explore the impact of varying the circle detection parameter on the validity of cHT cone counting and discuss the potential role of using this algorithm in detecting both cones and rods separately.OCIS codes: (100.0100) Image processing, (170.3880) Medical and biological imaging, (110.1080) Active or adaptive optics, (170.4470) Ophthalmology 相似文献
35.
36.
Rong Liu Stephanie Curry Patricia McMonagle Wendy W. Yeh Steven W. Ludmerer Patricia A. Jumes William L. Marshall Stephanie Kong Paul Ingravallo Stuart Black Irene Pak Mark J. DiNubile Anita Y. M. Howe 《Antimicrobial agents and chemotherapy》2015,59(11):6922-6929
Elbasvir is an investigational NS5A inhibitor with in vitro activity against multiple HCV genotypes. Antiviral activity of elbasvir was measured in replicons derived from wild-type or resistant variants of genotypes 1a, 1b, and 3. The barrier to resistance was assessed by the number of resistant colonies selected by exposure to various elbasvir concentrations. In a phase 1b dose-escalating study, virologic responses were determined in 48 noncirrhotic adult men with chronic genotype 1 or 3 infections randomized to placebo or elbasvir from 5 to 50 mg (genotype 1) or 10 to 100 mg (genotype 3) once daily for 5 days. The NS5A gene was sequenced from plasma specimens obtained before, during, and after treatment. Elbasvir suppressed the emergence of resistance-associated variants (RAVs) in vitro in a dose-dependent manner. Variants selected by exposure to high elbasvir concentrations typically encoded multiple amino acid substitutions (most commonly involving loci 30, 31, and 93), conferring high-level elbasvir resistance. In the monotherapy study, patients with genotype 1b had greater reductions in HCV RNA levels than patients with genotype 1a at all elbasvir doses; responses in patients with genotype 3 were generally less pronounced than for genotype 1, particularly at lower elbasvir doses. M28T, Q30R, L31V, and Y93H in genotype 1a, L31V and Y93H in genotype 1b, and A30K, L31F, and Y93H in genotype 3 were the predominant RAVs selected by elbasvir monotherapy. Virologic findings in patients were consistent with the preclinical observations. NS5A-RAVs emerged most often at amino acid positions 28, 30, 31, and 93 in both the laboratory and clinical trial. (The MK-8742 P002 trial has been registered at ClinicalTrials.gov under identifier .) NCT01532973相似文献
37.
In Woong Han Kyeongwon Cho Youngju Ryu Sang Hyun Shin Jin Seok Heo Dong Wook Choi Myung Jin Chung Oh Chul Kwon Baek Hwan Cho 《World journal of gastroenterology : WJG》2020,26(30):4453-4464
BACKGROUND Despite advancements in operative technique and improvements in postoperative managements,postoperative pancreatic fistula(POPF) is a life-threatening complication following pancreatoduodenectomy(PD).There are some reports to predict POPF preoperatively or intraoperatively,but the accuracy of those is questionable.Artificial intelligence(AI) technology is being actively used in the medical field,but few studies have reported applying it to outcomes after PD.AIM To develop a risk prediction platform for POPF using an AI model.METHODS Medical records were reviewed from 1769 patients at Samsung Medical Center who underwent PD from 2007 to 2016.A total of 38 variables were inserted into AI-driven algorithms.The algorithms tested to make the risk prediction platform were random forest(RF) and a neural network(NN) with or without recursive feature elimination(RFE).The median imputation method was used for missing values.The area under the curve(AUC) was calculated to examine the discriminative power of algorithm for POPF prediction.RESULTS The number of POPFs was 221(12.5%) according to the International Study Group of Pancreatic Fistula definition 2016.After median imputation,AUCs using 38 variables were 0.68 ± 0.02 with RF and 0.71 ± 0.02 with NN.The maximal AUC using NN with RFE was 0.74.Sixteen risk factors for POPF were identified by AI algorithm:Pancreatic duct diameter,body mass index,preoperative serum albumin,lipase level,amount of intraoperative fluid infusion,age,platelet count,extrapancreatic location of tumor,combined venous resection,co-existing pancreatitis,neoadjuvant radiotherapy,American Society of Anesthesiologists' score,sex,soft texture of the pancreas,underlying heart disease,and preoperative endoscopic biliary decompression.We developed a web-based POPF prediction platform,and this application is freely available at http://popfrisk.smchbp.org.CONCLUSION This study is the first to predict POPF with multiple risk factors using AI.This platform is reliable(AUC 0.74),so it could be used to select patients who need especially intense therapy and to preoperatively establish an effective treatment strategy. 相似文献
38.
Tang KH Ma S Lee TK Chan YP Kwan PS Tong CM Ng IO Man K To KF Lai PB Lo CM Guan XY Chan KW 《Hepatology (Baltimore, Md.)》2012,55(3):807-820
A novel theory in the field of tumor biology postulates that cancer growth is driven by a population of stem-like cells, called tumor-initiating cells (TICs). We previously identified a TIC population derived from hepatocellular carcinoma (HCC) that is characterized by membrane expression of CD133. Here, we describe a novel mechanism by which these cells mediate tumor growth and angiogenesis by systematic comparison of the gene expression profiles between sorted CD133 liver subpopulations through genome-wide microarray analysis. A significantly dysregulated interleukin-8 (IL-8) signaling network was identified in CD133(+) liver TICs obtained from HCC clinical samples and cell lines. IL-8 was found to be overexpressed at both the genomic and proteomic levels in CD133(+) cells isolated from HCC cell lines or clinical samples. Functional studies found enhanced IL-8 secretion in CD133(+) liver TICs to exhibit a greater ability to self-renew, induce tumor angiogenesis, and initiate tumors. In further support of these observations, IL-8 repression in CD133(+) liver TICs by knockdown or neutralizing antibody abolished these effects. Subsequent studies of the IL-8 functional network identified neurotensin (NTS) and CXCL1 to be preferentially expressed in CD133(+) liver TICs. Addition of exogenous NTS resulted in concomitant up-regulation of IL-8 and CXCL1 with simultaneous activation of p-ERK1/2 and RAF-1, both key components of the mitogen-activated protein kinase (MAPK) pathway. Enhanced IL-8 secretion by CD133(+) liver TICs can in turn activate an IL-8-dependent feedback loop that signals through the MAPK pathway. Further, in its role as a liver TIC marker CD133 also plays a functional part in regulating tumorigenesis of liver TICs by way of regulating NTS, IL-8, CXCL1, and MAPK signaling. CONCLUSION: CD133(+) liver TICs promote angiogenesis, tumorigenesis, and self-renewal through NTS-induced activation of the IL-8 signaling cascade. 相似文献
39.
40.