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   343383篇
  免费   28717篇
  国内免费   4121篇
耳鼻咽喉   3785篇
儿科学   9232篇
妇产科学   9412篇
基础医学   94007篇
口腔科学   11609篇
临床医学   24925篇
内科学   54600篇
皮肤病学   11748篇
神经病学   18041篇
特种医学   10537篇
外国民族医学   75篇
外科学   44435篇
综合类   10893篇
现状与发展   19篇
一般理论   21篇
预防医学   6919篇
眼科学   3838篇
药学   10268篇
  25篇
中国医学   564篇
肿瘤学   51268篇
  2023年   5963篇
  2022年   8526篇
  2021年   11005篇
  2020年   10969篇
  2019年   7995篇
  2018年   9896篇
  2017年   10081篇
  2016年   10519篇
  2015年   12100篇
  2014年   21197篇
  2013年   19214篇
  2012年   15149篇
  2011年   16184篇
  2010年   16923篇
  2009年   15911篇
  2008年   12577篇
  2007年   12824篇
  2006年   11736篇
  2005年   10931篇
  2004年   9949篇
  2003年   9436篇
  2002年   9226篇
  2001年   9243篇
  2000年   8851篇
  1999年   8384篇
  1998年   5128篇
  1997年   4292篇
  1996年   4329篇
  1995年   3764篇
  1994年   3349篇
  1993年   3097篇
  1992年   6464篇
  1991年   6350篇
  1990年   6218篇
  1989年   5865篇
  1988年   5703篇
  1987年   3092篇
  1986年   1542篇
  1985年   1981篇
  1984年   1909篇
  1983年   1674篇
  1982年   1585篇
  1981年   1389篇
  1980年   1319篇
  1979年   1251篇
  1978年   1182篇
  1977年   943篇
  1976年   847篇
  1974年   870篇
  1973年   849篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
11.
《Clinical breast cancer》2022,22(8):e850-e862
BackgroundBreast cancer, an emerging global challenge, is evidenced by recent studies of miRNAs involvement in DNA repair gene variants (MRE11, RAD50, and NBN as checkpoint sensor genes (CSG) – MRN-CSG). The identification of various mutations in MRN-CSG and their interactions with miRNAs is still not understood. The emerging studies of miR-2909 involvement in other cancers led us to explore its role as molecular mechanistic marker in breast cancer.Materials and MethodsThe genomic and proteomic data of MRN-CSG of breast cancer patients (8426 samples) was evaluated to identify the mutation types linked with the patient's survival rate. Additionally, molecular, 3D-structural and functional analysis was performed to identify miR-2909 as regulator of MRN-CSG.ResultsThe genomic and proteomic data analysis shows genetic alterations with majority of missense mutations [RAD50 (0.7%), MRE11 (1.5%), and NBN (11%)], though with highest MRE11 mRNA expression in invasive ductal breast carcinoma as compared to other breast cancer types. The Kaplan–Meier survival curves suggest higher survival rate for unaltered groups as compared to the altered group. Network analysis and disease association of miR-2909 and MRN-CSG shows strong interactions with other partners. The molecular hybridization between miR-2909-RAD50 and miR-2909-MRE11 complexes showed thermodynamically stable structures. Further, argonaute protein, involved in RNA silencing, docking studies with miR-MRE11-mRNA and miR-RAD50-mRNA hybridized complexes showed strong binding affinity.ConclusionThe results suggest that miR-2909 forms strong thermodynamically stable molecular hybridized complexes with MRE11 and RAD50 mRNAs which further strongly interacts with argonaute protein to show potential molecular mechanistic role in breast cancer.  相似文献   
12.
《Cancer cell》2022,40(3):318-334.e9
  1. Download : Download high-res image (268KB)
  2. Download : Download full-size image
  相似文献   
13.
14.
15.
In forensic medicine, although various alcohols have been reported as indicators of decomposition in collected blood, no studies have examined short-chain fatty acids as indicators. In this study, the blood n-butyric acid concentration was quantified, and the association between n-butyric acid and decomposition was investigated to determine whether the detection of n-butyric acid could be a new indicator of decomposition. Among the forensic autopsies performed from 2016 to 2018 in our laboratory, the cases were divided into decomposed (n = 20) and non-decomposed (n = 20) groups based on macroscopic findings. Blood samples collected at the time of autopsy were derivatized with 3-nitrophenylhydrazine hydrochloride after solid-phase extraction. The n-butyric acid concentration was measured using liquid chromatography–tandem mass spectrometry. In addition, ethanol and n-propanol were measured using a gas chromatography-flame ionization detector. There was a significant difference (p < 0.01) in the concentrations of n-butyric acid between the decomposed and non-decomposed groups (0.343 ± 0.259 [0.030–0.973] and 0.003 ± 0.002 [0.001–0.007] mg/mL, respectively). In the decomposed group, n-butyric acid was detected at high concentrations, even in cases where n-propanol was low. These results suggest that n-butyric acid is more likely to be an indicator of blood decomposition than n-propanol.  相似文献   
16.
Intratumor heterogeneity is a main cause of the dismal prognosis of glioblastoma (GBM). Yet, there remains a lack of a uniform assessment of the degree of heterogeneity. With a multiscale approach, we addressed the hypothesis that intratumor heterogeneity exists on different levels comprising traditional regional analyses, but also innovative methods including computer-assisted analysis of tumor morphology combined with epigenomic data. With this aim, 157 biopsies of 37 patients with therapy-naive IDH-wildtype GBM were analyzed regarding the intratumor variance of protein expression of glial marker GFAP, microglia marker Iba1 and proliferation marker Mib1. Hematoxylin and eosin stained slides were evaluated for tumor vascularization. For the estimation of pixel intensity and nuclear profiling, automated analysis was used. Additionally, DNA methylation profiling was conducted separately for the single biopsies. Scoring systems were established to integrate several parameters into one score for the four examined modalities of heterogeneity (regional, cellular, pixel-level and epigenomic). As a result, we could show that heterogeneity was detected in all four modalities. Furthermore, for the regional, cellular and epigenomic level, we confirmed the results of earlier studies stating that a higher degree of heterogeneity is associated with poorer overall survival. To integrate all modalities into one score, we designed a predictor of longer survival, which showed a highly significant separation regarding the OS. In conclusion, multiscale intratumor heterogeneity exists in glioblastoma and its degree has an impact on overall survival. In future studies, the implementation of a broadly feasible heterogeneity index should be considered.  相似文献   
17.
《Autoimmunity reviews》2022,21(9):103143
Autoimmune diseases (AID) are increasingly prevalent conditions which comprise more than 100 distinct clinical entities that are responsible for a great disease burden worldwide. The early recognition of these diseases is key for preventing their complications and for tailoring proper management. In most cases, autoantibodies, regardless of their potential pathogenetic role, can be detected in the serum of patients with AID, helping clinicians in making a definitive diagnosis and allowing screening strategies for early -and sometimes pre-clinical- diagnosis. Despite their undoubted crucial role, in a minority of cases, patients with AID may not show any autoantibody, a condition that is referred to as seronegative AID. Suboptimal accuracy of the available laboratory tests, antibody absorption, immunosuppressive therapy, immunodeficiencies, antigen exhaustion, and immunosenescence are the main possible determinants of seronegative AID. Indeed, in seronegative AID, the diagnosis is more challenging and must rely on clinical features and on other available tests, often including histopathological evaluation and radiological diagnostic tests. In this review, we critically dissect, in a narrative fashion, the possible causes of seronegativity, as well as the diagnostic and management implications, in several AID including autoimmune gastritis, celiac disease, autoimmune liver disease, rheumatoid arthritis, autoimmune encephalitis, myasthenia gravis, Sjögren’s syndrome, antiphospholipid syndrome, and autoimmune thyroid diseases.  相似文献   
18.
《Cancer cell》2022,40(2):153-167.e11
  1. Download : Download high-res image (229KB)
  2. Download : Download full-size image
  相似文献   
19.
《Mucosal immunology》2022,15(5):896-907
Environmental microbial triggers shape the development and functionality of the immune system. Alveolar macrophages (AMs), tissue-resident macrophages of the lungs, are in constant and direct contact with inhaled particles and microbes. Such exposures likely impact AM reactivity to subsequent challenges by immunological imprinting mechanisms referred to as trained immunity. Here, we investigated whether a ubiquitous microbial compound has the potential to induce AM training in vivo. We discovered that intranasal exposure to ambient amounts of lipopolysaccharide (LPS) induced a pronounced AM memory response, characterized by enhanced reactivity upon pneumococcal challenge. Exploring the mechanistic basis of AM training, we identified a critical role of type 1 interferon signaling and found that inhibition of fatty acid oxidation and glutaminolysis significantly attenuated the training effect. Notably, adoptive transfer of trained AMs resulted in increased bacterial loads and tissue damage upon subsequent pneumococcal infection. In contrast, intranasal pre-exposure to LPS promoted bacterial clearance, highlighting the complexity of stimulus-induced immune responses, which likely involve multiple cell types and may depend on the local immunological and metabolic environment. Collectively, our findings demonstrate the profound impact of ambient microbial exposure on pulmonary immune memory and reveal tissue-specific features of trained immunity.  相似文献   
20.
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