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   1117532篇
  免费   78624篇
  国内免费   4926篇
耳鼻咽喉   15486篇
儿科学   34951篇
妇产科学   29080篇
基础医学   157577篇
口腔科学   30296篇
临床医学   100612篇
内科学   208666篇
皮肤病学   24753篇
神经病学   83309篇
特种医学   44929篇
外国民族医学   223篇
外科学   168079篇
综合类   32067篇
现状与发展   7篇
一般理论   268篇
预防医学   77772篇
眼科学   25773篇
药学   91492篇
  66篇
中国医学   6270篇
肿瘤学   69406篇
  2021年   9412篇
  2019年   9547篇
  2018年   13224篇
  2017年   10677篇
  2016年   11846篇
  2015年   13891篇
  2014年   18507篇
  2013年   25300篇
  2012年   35251篇
  2011年   37102篇
  2010年   22369篇
  2009年   20526篇
  2008年   32930篇
  2007年   34962篇
  2006年   35342篇
  2005年   33409篇
  2004年   31244篇
  2003年   29827篇
  2002年   28516篇
  2001年   60757篇
  2000年   62061篇
  1999年   51439篇
  1998年   12266篇
  1997年   10813篇
  1996年   10686篇
  1995年   10572篇
  1994年   9574篇
  1993年   8970篇
  1992年   37922篇
  1991年   36406篇
  1990年   35861篇
  1989年   34373篇
  1988年   30945篇
  1987年   30057篇
  1986年   28278篇
  1985年   26496篇
  1984年   19213篇
  1983年   16114篇
  1982年   8808篇
  1979年   17005篇
  1978年   11389篇
  1977年   10196篇
  1976年   8822篇
  1975年   10052篇
  1974年   11640篇
  1973年   11264篇
  1972年   10747篇
  1971年   10086篇
  1970年   9248篇
  1969年   8932篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Modified-release opioids are often prescribed for the management of moderate to severe acute pain following total hip and knee arthroplasty, despite recommendations against their use due to increasing concerns regarding harm. The primary objective of this multicentre study was to examine the impact of modified-release opioid use on the incidence of opioid-related adverse events compared with immediate-release opioid use, among adult inpatients following total hip or knee arthroplasty. Data for total hip and knee arthroplasty inpatients receiving an opioid analgesic for postoperative analgesia during hospitalisation were collected from electronic medical records of three tertiary metropolitan hospitals in Australia. The primary outcome was the incidence of opioid-related adverse events during hospital admission. Patients who received modified with or without immediate-release opioids were matched to those receiving immediate-release opioids only (1:1) using nearest neighbour propensity score matching with patient and clinical characteristics as covariates. This included total opioid dose received. In the matched cohorts, patients given modified-release opioids (n = 347) experienced a higher incidence of opioid-related adverse events overall, compared with those given immediate-release opioids only (20.5%, 71/347 vs. 12.7%, 44/347; difference in proportions 7.8% [95%CI 2.3–13.3%]). Modified-release opioid use was associated with an increased risk of harm when used for acute pain during hospitalisation after total hip or knee arthroplasty.  相似文献   
2.
Colorectal cancer (CRC) is the third most diagnosed cancer and the second leading cause of cancer-related mortality in the United States. Across the globe, people in the age group older than 50 are at a higher risk of CRC. Genetic and environmental risk factors play a significant role in the development of CRC. If detected early, CRC is preventable and treatable. Currently, available screening methods and therapies for CRC treatment reduce the incidence rate among the population, but the micrometastasis of cancer may lead to recurrence. Therefore, the challenge is to develop an alternative therapy to overcome this complication. Nanotechnology plays a vital role in cancer treatment and offers targeted chemotherapies directly and selectively to cancer cells, with enhanced therapeutic efficacy. Additionally, nanotechnology elevates the chances of patient survival in comparison to traditional chemotherapies. The potential of nanoparticles includes that they may be used simultaneously for diagnosis and treatment. These exciting properties of nanoparticles have enticed researchers worldwide to unveil their use in early CRC detection and as effective treatment. This review discusses contemporary methods of CRC screening and therapies for CRC treatment, while the primary focus is on the theranostic approach of nanotechnology in CRC treatment and its prospects. In addition, this review aims to provide knowledge on the advancement of nanotechnology in CRC and as a starting point for researchers to think about new therapeutic approaches using nanotechnology.  相似文献   
3.
Pancreatic cancer (PC) is a cancer of the digestive system, and pancreatic ductal adenocarcinoma (PDAC) accounts for approximately 90% of all PC cases. Exosomes derived from PDAC (PDAC-exosomes) promote PDAC development and metastasis. Exosomes are nanoscale vesicles secreted by most cells, which can carry biologically active molecules and mediate communication and cargo transportation among cells. Recent studies have focused on transforming exosomes into good drug delivery systems (DDSs) to improve the clinical treatment of PDAC. This review considers PDAC as the main research object to introduce the role of PDAC-exosomes in PDAC development and metastasis. This review focuses on the following two themes: (a) the great potential of PDAC-exosomes as new diagnostic markers for PDAC, and (b) the transformation of exosomes into potential DDSs.  相似文献   
4.
Objective: Cancer is a huge problem of disease globally. Today, the percentage of people die from cancer is more than a combination of various diseases. In females, most common types of malignancies that occur are breast and cervical. The present focus has been shifted on medicinal plants as a form of therapy and there is a constant need to identify new therapeutic agents. Choerospondias axillaris (C. axillaris), an underutilized fruit, has been used in the remedy of various diseases. In the present communication, we evaluated the molecular mechanism of C. axillaris methanol extract in regulating cell death in human breast cancer cells (MDA-MB-231). Methods: Methanol extract of C. axillaris was prepared and compounds were screened by Gas chromatography-mass spectrometry. The effect of fruit extract was determined on MDA-MB-231 cells by MTT ((3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay and to analyse the molecular mechanism of human breast cancer cells after treating with fruit extract, protein profiling study was performed by two-dimensional gel electrophoresis. Results: A total 9 differentially expressed proteins were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS/MS) analysis. Among 9 identified proteins, synphilin-1 protein was found to be significantly downregulated, validated by western blot and RT-qPCR analysis. Possible interacting partners of synphilin-1 (SNCAIP) were analyzed for their possible role in cancer by the in-silico method. Conclusion: Our data implicate that the presence of bioactive compound(s) in C. axillaris fruits might play an important role in inhibiting the proliferation of breast carcinoma cells and Synphilin-1 protein may play a role of apoptotic function.  相似文献   
5.
Microbial co-infections are another primary concern in patients with coronavirus disease 2019 (COVID-19), yet it is an untouched area among researchers. Preliminary data and systematic reviews only show the type of pathogens responsible for that, but its pathophysiology is still unknown. Studies show that these microbial co-infections are hospital-acquired/nosocomial infections, and patients admitted to intensive care units with invasive mechanical ventilation are highly susceptible to it. Patients with COVID-19 had elevated inflammatory cytokines and a weakened cell-mediated immune response, with lower CD4+ T and CD8+ T cell counts, indicating vulnerability to various co-infections. Despite this, there are only a few studies that recommend the management of co-infections.  相似文献   
6.
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - Heavy metal concentrations in surface soils of Reserved Forests (RFs) have a significant impact on...  相似文献   
7.
Clinical Rheumatology - Aimed to evaluate the time elapsed between the onset of early symptoms and the diagnosis of fibromyalgia syndrome (FMS), the delays in diagnosis and frequent physician...  相似文献   
8.
目的观察分析眼球钝挫伤合并外伤性晶状体脱位患者周边隐匿性视网膜病变的临床特点及预后。 方法本研究纳入2013年1月至2020年1月在柳州市人民医院眼科住院诊断为眼球钝挫伤合并外伤性晶状体脱位,并行23G微创玻璃体切割联合白内障摘除手术的72例(72眼)患者。根据裂隙灯和超声生物显微镜(UBM)检查,将患者分为晶状体不全脱位组和全脱位组,详细记录2组患者的术中周边视网膜病变情况,并分析其临床特征及疗效。 结果眼球钝挫伤合并外伤性晶状体脱位患者中有周边隐匿性视网膜病变的占72.22%,其中晶状体不全脱位组发生率高达80.95%,显著大于晶状体全脱位组的60.00%(P<0.05)。2组患者的周边隐匿性视网膜病变均以隐匿性视网膜裂孔、变性和出血为最常见。所有患者术后视网膜情况稳定,视力预后较好。 结论眼球钝挫伤合并外伤性晶状体脱位患者常出现周边隐匿性视网膜病变,最常见的是视网膜裂孔、出血、变性。23G微创玻璃体切割联合白内障摘除手术是有效治疗手段,具有创伤小、并发症少的优势。  相似文献   
9.
Maternal and Child Health Journal - Early life exposures can have an impact on a child’s developmental trajectory and children born late preterm (34–36 weeks gestational age)...  相似文献   
10.
【目的】 通过比较2019年获得“中国科技期刊卓越行动计划”领军期刊项目资助的期刊(以下简称“领军期刊”)与其对标期刊,探索我国科技期刊缩小与世界顶级期刊差距的对策,为我国一流科技期刊建设提供参考和借鉴。【方法】 利用Web of Science (WoS) 数据库和期刊官网,检索并总结领军期刊与其对标期刊的各项指标数据,分析领军期刊最近5年来的发展情况。【结果】 22种领军期刊的主要指标数据明显上升。2020年领军期刊共发表Article 和Review文章4025篇,比2019年的2630篇增长53.0%,2020年刊均载文量为183篇,比2019年的120篇增长53.0%;领军期刊总被引频次由2019年的99767 次大幅增长至2020年的153610次,增幅达54.0%;2020年领军期刊的平均被引半衰期为3.73年,而对标期刊的平均被引半衰期为9.35年。2020年,16种领军期刊跻身JCR学科排名前10%,10种领军期刊跻身JCR学科排名前5%。【结论】 领军期刊应构建良性的期刊发展生态、动态调整期刊的发展目标、紧扣国家战略和重大需求布局期刊发展方向、重视人才发展与储备、构建自主可控的国际传播平台与渠道,以完成引领行业发展的使命任务,实现可持续发展,从而带动我国期刊行业的整体发展与进步。  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