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   2566篇
  免费   219篇
  国内免费   19篇
耳鼻咽喉   12篇
儿科学   70篇
妇产科学   63篇
基础医学   334篇
口腔科学   105篇
临床医学   302篇
内科学   559篇
皮肤病学   78篇
神经病学   245篇
特种医学   65篇
外科学   278篇
综合类   16篇
一般理论   1篇
预防医学   254篇
眼科学   13篇
药学   199篇
中国医学   5篇
肿瘤学   205篇
  2024年   5篇
  2023年   67篇
  2022年   94篇
  2021年   140篇
  2020年   118篇
  2019年   106篇
  2018年   130篇
  2017年   101篇
  2016年   109篇
  2015年   124篇
  2014年   135篇
  2013年   165篇
  2012年   193篇
  2011年   212篇
  2010年   107篇
  2009年   112篇
  2008年   169篇
  2007年   145篇
  2006年   117篇
  2005年   110篇
  2004年   99篇
  2003年   72篇
  2002年   71篇
  2001年   7篇
  2000年   5篇
  1999年   10篇
  1998年   14篇
  1997年   9篇
  1996年   6篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   5篇
  1991年   6篇
  1990年   8篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   3篇
  1985年   1篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1976年   2篇
  1974年   1篇
  1969年   1篇
  1922年   1篇
排序方式: 共有2804条查询结果,搜索用时 13 毫秒
51.
Background Campylobacter is one of the most frequent causes of bacterial gastroenteritis. Campylobacter outbreaks are rarely reported, which could be a reflection of a surveillance without routine molecular typing. We have previously shown that numerous small outbreak-like clusters can be detected when whole genome sequencing (WGS) data of clinical Campylobacter isolates was applied.AimTyping-based surveillance of Campylobacter infections was initiated in 2019 to enable detection of large clusters of clinical isolates and to match them to concurrent retail chicken isolates in order to react on ongoing outbreaks.MethodsWe performed WGS continuously on isolates from cases (n = 701) and chicken meat (n = 164) throughout 2019. Core genome multilocus sequence typing was used to detect clusters of clinical isolates and match them to isolates from chicken meat.ResultsSeventy-two clusters were detected, 58 small clusters (2–4 cases) and 14 large clusters (5–91 cases). One third of the clinical isolates matched isolates from chicken meat. One large cluster persisted throughout the whole year and represented 12% of all studied Campylobacter cases. This cluster type was detected in several chicken samples and was traced back to one slaughterhouse, where interventions were implemented to control the outbreak.ConclusionOur WGS-based surveillance has contributed to an improved understanding of the dynamics of the occurrence of Campylobacter strains in chicken meat and the correlation to clusters of human cases.  相似文献   
52.
53.
OBJECTIVE: To evaluate hypothalamic-pituitary-adrenal (HPA) axis function in patients with recent onset polymyalgia rheumatica (PMR) not previously treated with glucocorticoids; and to detect possible correlations between adrenal hormone levels, interleukin 6 (IL-6), and other acute phase reactants at baseline and during 12 months of glucocorticoid treatment. METHODS: Forty-one PMR patients of both sexes with recent onset disease and healthy sex and age matched controls were enrolled into a longitudinal study. Patients were monitored for serum cortisol, dehydroepiandrosterone sulfate (DHEAS), androstenedione (ASD), and clinical and laboratory measures of disease activity such as C-reactive protein and IL-6 concentrations at baseline and after 1, 3, 6, 9 and 12 months of glucocorticoid treatment. To assess dynamic HPA axis function, serum cortisol and plasma adrenocorticotropic hormone (ACTH) levels were evaluated in another 8 patients with recent onset PMR not treated with glucocorticoid in comparison to controls after challenge with ovine corticotropin releasing hormone (oCRH) test. In addition, serum cortisol and 17-hydroxyprogesterone (17-OHP) levels were evaluated after stimulation with low dose (1 microg) intravenous ACTH. RESULTS: Serum cortisol and ASD levels of all PMR patients at baseline did not differ from controls. During followup, cortisol levels dipped at one and 3 months. Serum DHEAS levels in all patients were significantly lower than in controls at baseline. In female PMR patients a significant correlation was found at baseline between cortisol levels and duration of disease. Serum concentrations of IL-6 at baseline were significantly higher in PMR patients than in controls. During 12 months of glucocorticoid treatment IL-6 levels dropped significantly at one month; thereafter they remained stable and did not increase again despite tapering of the glucocorticoid dose. After oCRH stimulation, a similar cortisol response was found in patients and controls. After ACTH administration, a significant cortisol peak was detected in patients and controls, whereas no significant difference in cortisol area-under-the-curve (AUC) was found between the groups. In contrast, ACTH induced a significantly higher (p < 0.05) peak of 17-OHP and AUC in PMR patients than in controls. CONCLUSION: This study found reduced production of adrenal hormones (cortisol, DHEAS) at baseline in patients with active and untreated PMR. The defect seems mainly related to altered adrenal responsiveness to the ACTH stimulation (i.e., increased 17-OHP), at least in untreated patients. The 12 month glucocorticoid treatment of patients reduced the production of inflammatory mediators (i.e., IL-6) in a stable manner that persisted after glucocorticoids were tapered.  相似文献   
54.
CONTEXT: Hepatic lipase plays a pivotal role in the metabolism of high-density lipoprotein (HDL) and low-density lipoprotein by involvement in reverse cholesterol transport and the formation of atherogenic small dense low-density lipoprotein. OBJECTIVES: The objective was to investigate the impact of variants in LIPC on metabolic traits and type 2 diabetes in a large sample of Danes. Because behavioral factors influence hepatic lipase activity, we furthermore examined possible gene-environment interactions in the population-based Inter99 study. DESIGN: The LIPC -250G>A (rs2070895) variant was genotyped in the Inter99 study (n = 6070), the Anglo-Danish-Dutch Study of Intensive Treatment in People with Screen Detected Diabetes in Primary Care Denmark screening cohort of individuals with risk factors for undiagnosed type 2 diabetes (n = 8662), and in additional type 2 diabetic patients (n = 1,064) and glucose-tolerant control subjects (n = 360). RESULTS: In the Inter99 study, the A allele of rs2070895 associated with a 0.057 mmol/liter [95% confidence interval (CI) 0.039-0.075] increase in fasting serum HDL-cholesterol (HDL-c) (P = 8 x 10(-10)) supported by association in the Anglo-Danish-Dutch Study of Intensive Treatment in People with Screen Detected Diabetes in Primary Care study [0.038 mmol/liter per allele (95% CI 0.024-0.053); P = 2 x 10(-7)). The allelic effect on HDL-c was modulated by interaction with self-reported physical activity (P(interaction) = 0.002) because vigorous physically active homozygous A-allele carriers had a 0.30 mmol/liter (95% CI 0.22-0.37) increase in HDL-c compared with homozygous G-allele carriers. CONCLUSIONS: We validate the association of LIPC promoter variation with fasting serum HDL-c and present data supporting an interaction with physical activity implying an increased effect on HDL-c in vigorous physically active subjects carrying the -250 A allele. This interaction may have potential implications for public health and disease prevention.  相似文献   
55.
Genome-wide association studies have identified a number of susceptibility loci in sporadic Parkinson's disease (PD). Recent larger studies and meta-analyses have greatly expanded the list of proposed association signals. We performed a case-control replication study in a Scandinavian population, analyzing samples from 1345 unrelated PD patients and 1225 control subjects collected by collaborating centers in Norway and Sweden. Single-nucleotide polymorphisms representing 18 loci previously reported at genome-wide significance levels were genotyped, as well as 4 near-significant, suggestive, loci. We replicated 11 association signals at p < 0.05 (SNCA, STK39, MAPT, GPNMB, CCDC62/HIP1R, SYT11, GAK, STX1B, MCCC1/LAMP3, ACMSD, and FGF20). The more recently nominated susceptibility loci were well represented among our positive findings, including 3 which have not previously been validated in independent studies. Conversely, some of the more well-established loci failed to replicate. While future meta-analyses should corroborate disease associations further on the level of common markers, efforts to pinpoint functional variants and understand the biological implications of each risk locus in PD are also warranted.  相似文献   
56.
In pathogenic simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infections, the translocation of microbial products from the gastrointestinal (GI) tract to portal and systemic circulation has been proposed as a major driver of the chronic immune activation that is associated with disease progression. Consistently, microbial translocation is not present in nonpathogenic SIV infections of natural host species. In vivo studies demonstrated that HIV/SIV-associated microbial translocation results from a series of immunopathological events occurring at the GI mucosa: (i) early and severe mucosal CD4+ depletion, (ii) mucosal immune hyperactivation/persistent inflammation; (iii) damage to the integrity of the intestinal epithelium with enterocyte apoptosis and tight junction disruption; and (iv) subverted the gut microbiome, with a predominance of opportunistic bacteria. Direct in situ evidence of microbial translocation has been provided for SIV-infected rhesus macaques showing translocated microbial products in the intestinal lamina propria and distant sites. While the mechanisms by which microbial translocation causes immune activation remain controversial, a key pathogenic event appears to be innate immunity activation via Toll-like receptors and other pathogen recognition receptors. Accumulating clinical observations suggest that microbial translocation might affect HIV disease progression, response to therapy, and non-AIDS comorbidities. Given its detrimental effect on overall immunity, several interventions to prevent/block microbial translocation are currently under investigation as novel therapeutic agents for HIV/AIDS.  相似文献   
57.
58.
European Journal of Clinical Microbiology & Infectious Diseases - We aimed to describe the microbiology of parapharyngeal abscess (PPA) and point out the likely pathogens using the following...  相似文献   
59.
Clinical and Experimental Medicine - The aim of the study is to evaluate the prognostic value of early PCSK9 levels in non-intubated septic patients admitted to the emergency department. This...  相似文献   
60.
The purpose of the current study was twofold (a) to examine elite female athletes’ experiences of their menstrual cycle, with a focus upon the impact on training and competition performance and (b) the openness of conversation pertaining to the menstrual cycle with coaching and support staff. Following receipt of institutional ethical approval, individual semi‐structured interviews were conducted with 17 elite female athletes (25.5 ± 4.7 years) from multiple sports. Results revealed athletes’ experiencing a natural menstrual cycle reported physical symptoms alongside mood disturbances and reduced motivation to train. The decision to actively control the menstrual cycle was often triggered by a desire to reduce the effect on competition, to lessen anxieties about making required weight or reduce distraction to manage during competition. Athletes indicated an openness to talk about the menstrual cycle to other females, however, there was variation in the comfort athletes experienced regarding talking to male coaches. Overall, the findings highlight the need to educate elite athletes and coaches on the menstrual cycle, considering it in the same light as other physiological functions in sport to improve health, well‐being, and performance. Furthermore, providing education on how to construct positive conversations, equipping individuals with the correct terminology, and confidence to talk about the menstrual cycle will reduce some reservations identified through improved knowledge and understanding.  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