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   2943篇
  免费   156篇
  国内免费   4篇
耳鼻咽喉   32篇
儿科学   228篇
妇产科学   65篇
基础医学   349篇
口腔科学   43篇
临床医学   229篇
内科学   490篇
皮肤病学   68篇
神经病学   162篇
特种医学   83篇
外科学   383篇
综合类   99篇
预防医学   137篇
眼科学   54篇
药学   367篇
中国医学   18篇
肿瘤学   296篇
  2023年   14篇
  2022年   57篇
  2021年   91篇
  2020年   35篇
  2019年   68篇
  2018年   82篇
  2017年   57篇
  2016年   96篇
  2015年   89篇
  2014年   128篇
  2013年   137篇
  2012年   158篇
  2011年   212篇
  2010年   116篇
  2009年   81篇
  2008年   134篇
  2007年   149篇
  2006年   157篇
  2005年   118篇
  2004年   122篇
  2003年   111篇
  2002年   88篇
  2001年   52篇
  2000年   50篇
  1999年   52篇
  1998年   25篇
  1997年   14篇
  1996年   23篇
  1995年   18篇
  1994年   23篇
  1992年   31篇
  1991年   20篇
  1990年   33篇
  1989年   33篇
  1988年   36篇
  1987年   30篇
  1986年   32篇
  1985年   30篇
  1984年   25篇
  1983年   26篇
  1981年   12篇
  1979年   27篇
  1977年   14篇
  1976年   12篇
  1974年   23篇
  1972年   16篇
  1971年   17篇
  1970年   12篇
  1968年   16篇
  1967年   15篇
排序方式: 共有3103条查询结果,搜索用时 15 毫秒
91.
92.
93.
Metal sulfides are gaining prominence as conversion anode materials for lithium/sodium ion batteries due to their higher specific capacities but suffers from low stability and reversibility issues. In this work, the electrochemical properties of CuS anode material has been successfully enhanced by its composite formation using graphitic carbon nitride (g-C3N4). The CuS nanoparticles are distributed evenly in the exfoliated g-C3N4 matrix rendering higher electronic conductivity and space for volume alterations during the repeated discharge/charge cycles. The 0.8CuS:0.2g-C3N4 composite when used as an anode for lithium ion coin cell exhibits a reversible capacity of 478.4 mA h g−1 at a current rate of 2.0 A g−1 after a run of 1000 cycles which is better than that reported for CuS composites with any other carbon-based matrix. The performance is equally impressive when 0.8CuS:0.2g-C3N4 composite is used as an anode in a sodium ion coin cell and a reversible capacity of 408 mA h g−1 is obtained at a current rate of 2.0 A g−1 after a run of 800 cycles. A sodium ion full cell with NVP cathode and 0.8CuS:0.2g-C3N4 composite anode has been fabricated and cycled for 100 runs at a current rate of 0.1 A g−1. It can be inferred that the g-C3N4 matrix improves the ion transfer properties, alleviates the volume alteration happening in the anode during the discharge/charge process and also helps in preventing the leaching of polysulfides generated during the electrochemical process.

Metal sulfides are gaining prominence as conversion anode materials for lithium/sodium ion batteries due to their higher specific capacities but suffers from low stability and reversibility issues.  相似文献   
94.
The human medulloblastoma cell line, D283 Med, appears to be cytogenetically stable even after passage 121. Stem line number was determined to be 46, with intact X and Y chromosomes. The cell line is characterized by the presence of four marker chromosomes (M1 to M4).  相似文献   
95.
Background: Glyphosate is the most commonly used herbicide in the world and is purported to have a variety of health effects, including endocrine disruption and an elevated risk of several types of cancer. Blood DNA methylation has been shown to be associated with many other environmental exposures, but to our knowledge, no studies to date have examined the association between blood DNA methylation and glyphosate exposure.Objective: We conducted an epigenome-wide association study to identify DNA methylation loci associated with urinary glyphosate and its metabolite aminomethylphosphonic acid (AMPA) levels. Secondary goals were to determine the association of epigenetic age acceleration with glyphosate and AMPA and develop blood DNA methylation indices to predict urinary glyphosate and AMPA levels.Methods: For 392 postmenopausal women, white blood cell DNA methylation was measured using the Illumina Infinium MethylationEPIC BeadChip array. Glyphosate and AMPA were measured in two urine samples per participant using liquid chromatography–tandem mass spectrometry. Methylation differences at the probe and regional level associated with glyphosate and AMPA levels were assessed using a resampling-based approach. Probes and regions that had an false discovery rate q<0.1 in 90% of 1,000 subsamples of the study population were considered differentially methylated. Differentially methylated sites from the probe-specific analysis were combined into a methylation index. Epigenetic age acceleration from three epigenetic clocks and an epigenetic measure of pace of aging were examined for associations with glyphosate and AMPA.Results: We identified 24 CpG sites whose methylation level was associated with urinary glyphosate concentration and two associated with AMPA. Four regions, within the promoters of the MSH4, KCNA6, ABAT, and NDUFAF2/ERCC8 genes, were associated with glyphosate levels, along with an association between ESR1 promoter hypomethylation and AMPA. The methylation index accurately predicted glyphosate levels in an internal validation cohort. AMPA, but not glyphosate, was associated with greater epigenetic age acceleration.Discussion: Glyphosate and AMPA exposure were associated with DNA methylation differences that could promote the development of cancer and other diseases. Further studies are warranted to replicate our results, determine the functional impact of glyphosate- and AMPA-associated differential DNA methylation, and further explore whether DNA methylation could serve as a biomarker of glyphosate exposure. https://doi.org/10.1289/EHP10174  相似文献   
96.
97.
Carfilzomib is a second-in class Proteosome Inhibitor and has been approved for Relapsed/Refractory Multiple Myeloma (RRMM). We retrospectively retrieved and analyzed data of KPd combination both biweekly and weekly regimens at our centre from 1 st August 2017 and 31 st May 2020. Sixty-nine patients were treated with KPd with median age of 58 years. Median prior lines of chemotherapy were 2(1-15). Twenty-eight (40.5%) patients underwent autoSCT. Median no. of cycles was 4(1-12) and 3(1-13) with median time to response of 4(2-12) and 2(2-6) months in biweekly and once weekly regimen cohorts respectively. At last follow-up, overall response rate (ORR) was 65.2%{CR-n = 10 (14.5%), VGPR-n = 19 (27.5%), PR-n = 16 (23.2%)} with n = 13(18.8%) patients had PD and relapse was observed in n = 24(34.8%). Thirty (43.4%) patients received maintenance therapy {n = 21(70%)} or autoSCT {n = 9(30%)}. Common toxicities were anemia {n = 11(15.9 %)}, thrombocytopenia (n = 15(21.7%) and neutropenia (n = 16 (23.2%)}, hypertension {n = 28(40.5%)}, peripheral neuropathy (grade1/2) {n = 15(21.7%)}, infections [n = 18(26%) {bacterial [n = 9(13%),viral n = 7(10.1%), fungal n = 8(11.6%)}]. At a median follow-up of 18 months, the estimated median PFS was 11.3 months (95%C.I. 8.3– 14.2) whereas the estimated median OS was 28 months (95%C.I. 20.4-35.5) for the entire cohort. Mortality rate of 2.5% and 10% in two cohorts respectively. Commonest cause of death was PD and sepsis. KPD is a well-tolerated regimen for RRMM, which can be a bridge to ASCT, however with significant side effects.  相似文献   
98.
An 85 years old female presented with acute pain and weakness in left lower extremity and doppler evidence of femoropopliteal block was made which subsequently proved fatal. Necropsy revealed extensive amyloid deposition in the heart and amyloid angiopathy in rest of the organs.  相似文献   
99.
Journal of Digital Imaging - Cardiovascular diseases (CVDs) are the top ten leading causes of death worldwide. Atherosclerosis disease in the arteries is the main cause of the CVD, leading to...  相似文献   
100.
Blood pressure disorders are highly prevalent in the course of Parkinson's disease (PD). They relate to autonomic failure and are frequently associated with orthostatic hypotension, postprandial hypotension and supine hypertension. Supine hypertension, which may concern up to 50% of patients with PD and autonomic failure, is driven by residual sympathetic activity and changes in sensitivity of vascular adrenergic receptors. It can also be induced or worsened by antihypotensive drugs. Even if little data is available, a set of arguments suggests that supine hypertension sometimes requires treatment. This review will focus on recent data on the pathophysiology and the management of supine hypertension in the context of its association with orthostatic hypotension.  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