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   373588篇
  免费   24719篇
  国内免费   8616篇
耳鼻咽喉   4653篇
儿科学   10446篇
妇产科学   7134篇
基础医学   31177篇
口腔科学   8599篇
临床医学   40597篇
内科学   47395篇
皮肤病学   6314篇
神经病学   21543篇
特种医学   8719篇
外国民族医学   32篇
外科学   37813篇
综合类   55671篇
现状与发展   15篇
一般理论   29篇
预防医学   38194篇
眼科学   5661篇
药学   35836篇
  398篇
中国医学   32289篇
肿瘤学   14408篇
  2023年   5604篇
  2022年   8860篇
  2021年   14318篇
  2020年   13208篇
  2019年   18930篇
  2018年   16708篇
  2017年   13677篇
  2016年   11250篇
  2015年   10676篇
  2014年   21804篇
  2013年   23739篇
  2012年   20309篇
  2011年   21955篇
  2010年   17640篇
  2009年   16218篇
  2008年   15911篇
  2007年   16490篇
  2006年   14297篇
  2005年   12569篇
  2004年   10237篇
  2003年   8979篇
  2002年   7041篇
  2001年   6410篇
  2000年   5300篇
  1999年   4671篇
  1998年   3773篇
  1997年   3645篇
  1996年   3160篇
  1995年   3065篇
  1994年   2914篇
  1993年   2318篇
  1992年   2395篇
  1991年   2082篇
  1990年   1829篇
  1989年   1668篇
  1988年   1589篇
  1987年   1378篇
  1985年   4020篇
  1984年   4982篇
  1983年   3494篇
  1982年   3972篇
  1981年   3672篇
  1980年   3267篇
  1979年   2988篇
  1978年   2604篇
  1977年   1960篇
  1976年   2192篇
  1975年   1665篇
  1974年   1450篇
  1973年   1300篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.

Background

Resistin is an immunometabolic mediator that is elevated in several inflammatory disorders. A ligand for Toll-like receptor 4, resistin modulates the recruitment and activation of myeloid cells, notably neutrophils. Neutrophils are major drivers of cystic fibrosis (CF) lung disease, in part due to the release of human neutrophil elastase- and myeloperoxidase-rich primary granules, leading to tissue damage. Here we assessed the relationship of resistin to CF lung disease.

Methods

Resistin levels were measured in plasma and sputum from three retrospective CF cohorts spanning a wide range of disease. We also assessed the ability of neutrophils to secrete resistin upon activation in vitro. Finally, we constructed a multivariate model assessing the relationship between resistin levels and lung function.

Results

Plasma resistin levels were only marginally higher in CF than in healthy control subjects. By contrast, sputum resistin levels were very high in CF, reaching 50–100 fold higher levels than in plasma. Among CF patients, higher plasma resistin levels were associated with allergic bronchopulmonary aspergillosis, and higher sputum resistin levels were associated with CF-related diabetes. Mechanistically, in vitro release of neutrophil primary granules was concomitant with resistin secretion. Overall, sputum resistin levels were negatively correlated with CF lung function, independently of other variables (age, sex, and genotype).

Conclusions

Our data establish relationships between resistin levels in the plasma and sputum of CF patients that correlate with disease status, and identify resistin as a novel mechanistic link between neutrophilic inflammation and lung disease in CF.  相似文献   
93.
94.
95.
当代社会,老年人口比例呈现不断上升的趋势,老龄化问题日益严峻。因此,如何有效地延缓衰老不仅成为了世界医学研究的热点,也成为了全球亟待解决的问题。中医药在延缓衰老方面经验丰富,而滋阴药在此类研究中效果显著。本文通过整理滋阴药抗衰老作用机制的若干文献,对滋阴复方六味地黄丸、二至丸、左归丸及其他滋阴中药延缓衰老的机制研究进展进行综述。  相似文献   
96.
《Australian critical care》2019,32(6):540-559
ObjectivesThe objective of this review was to describe cardiovascular risk (CVR) assessment methods and to identify evidence-based practice recommendations when dealing with population at risk of developing cardiovascular diseases.Review methods and data sourcesA literature review following the Arksey and O'Malley scoping review methodology was conducted. By using appropriate key terms, literature searches were conducted in PubMed, SciELO, Cochrane Library, Dialnet, ENFISPO, Medigraphic, ScienceDirect, Cuiden, and Lilacs databases. A complementary search on websites related to the area of interest was conducted. Articles published in English or Spanish in peer-review journals between 2010 and 2017. Critical appraisal for methodological quality was conducted. Data was extracted using ad-hoc tables and qualitatively synthesized.ResultsAfter eliminating duplicates, 55 325 records remained, and 1432 records were selected for screening. Out of these, 88 full-text articles were selected for eligibility criteria, and finally, 67 studies were selected for this review, and 25 studies were selected for evidence synthesis. In total, 23 CVR assessment tools have been identified, pioneered by the Framingham study. Qualitative findings were grouped into four thematic areas: assessment tools and scores, CVR indicators, comparative models, and evidence-based recommendations.ConclusionsIt is necessary to adapt the instruments to the epidemiological reality of the population. The most appropriate way to estimate CVR is to choose the assessment tool that best suits individual conditions, accompanied by a comprehensive assessment of the patient. More research is required to determine a single, adequate, and reliable tool.  相似文献   
97.
《The ocular surface》2020,18(1):108-113
PurposeAromatase inhibitors (AIs) limit the synthesis of oestrogen in peripheral tissues thus lowering levels of oestrogen. The primary aim was to evaluate whether women treated with AIs have altered dry eye symptoms and signs. A sub-aim was to investigate whether symptoms of dry eye in postmenopausal women were associated with symptoms of non-eye pain, ocular pain and self-rated pain perception.MethodsThis cross-sectional, observational, single visit study recruited 56 postmenopausal women (mean age 64.1 + 7.9 years) and 52 undergoing AI treatment (mean age 66.6 + 9.0). Ocular symptoms (OSDI, MGD14) and pain questionnaires (PSQ, OPAS) were administered and signs of dry eye and meibomian gland dysfunction were evaluated.ResultsAlmost half of each group reported dry eye symptoms, defined as OSDI>12 (48% control, 46% AI). The PSQ score was significantly higher in the AI group (p = 0.04). Neither frequency or severity of dry eye (or MGD) symptoms scores were significantly different between groups. In the AI group, meibomian gland expressibility score was worse (p = 0.003); there were no differences in any other signs. Higher OSDI scores were associated with higher OPAS eye-pain scores (r = 0.49, p < 0.001), but not OPAS non-eye pain (r = 0.09, p = 0.35). Pain perception (PSQ) showed a moderate positive association with OPAS eye-pain (r = 0.30, p = 0.003).ConclusionsIn this study elevated ocular symptoms were observed in both the AI treated and the untreated groups, with no difference between the groups. Women undergoing AI treatment for early stage breast cancer had worse meibum expressibility score and increased pain perception compared to an untreated group of women.  相似文献   
98.
99.
BackgroundSome chronic obstructive pulmonary disease (COPD) patients develop hypoxemia with disease progression, with some even requiring long-term oxygen therapy (LTOT). Lung function, especially diffusing capacity, and the annual decline in PaO2, are reported to be predictive factors of chronic respiratory failure. However, the association between lung morphometry evaluated using computed tomography (CT) images and LTOT initiation is unknown.MethodsWe retrospectively evaluated the relationship between clinical indices, including pulmonary function, body mass index (BMI), and CT parameters, at baseline and LTOT initiation in two prospective COPD cohorts. In the Nara Medical University cohort (n = 76), the low attenuation area (LAA) and its fractal dimension (fractal D) were adapted as the indices for parenchymal destruction in CT images. The association between these CT measurements and LTOT initiation was replicated in the Kyoto University cohort (n = 130).ResultsIn the Nara Medical University cohort, lower BMI (hazard ratio [HR]:0.70, p = 0.006), lower % diffusing capacity (%DLCO) (HR: 0.92, p = 0.006), lower %DLCO/VA (HR, 0.90, p = 0.008), higher RV/TLC (HR, 1.26, p = 0.012), higher LAA% (HR: 1.18, p = 0.001), and lower fractal D (HR: 3.27 × 10?8, p < 0.001) were associated with LTOT initiation. Multivariate analysis in the Kyoto University cohort confirmed that lower %DLCO and lower fractal D were independently associated with LTOT initiation, whereas LAA% was not.ConclusionFractal D, which is the index for morphometric complexity of LAA in CT analysis, is predictive of LTOT initiation in COPD patients.  相似文献   
100.
《Vaccine》2022,40(11):1594-1605
In addition to providing pathogen-specific immunity, vaccines can also confer nonspecific effects (NSEs) on mortality and morbidity unrelated to the targeted disease. Immunisation with live vaccines, such as the BCG vaccine, has generally been associated with significantly reduced all-cause infant mortality. In contrast, some inactivated vaccines, such as the diphtheria, tetanus, whole-cell pertussis (DTPw) vaccine, have been controversially associated with increased all-cause mortality especially in female infants in high-mortality settings. The NSEs associated with BCG have been attributed, in part, to the induction of trained immunity, an epigenetic and metabolic reprograming of innate immune cells, increasing their responsiveness to subsequent microbial encounters. Whether non-live vaccines such as DTPw induce trained immunity is currently poorly understood. Here, we report that immunisation of mice with DTPw induced a unique program of trained immunity in comparison to BCG immunised mice. Altered monocyte and DC cytokine responses were evident in DTPw immunised mice even months after vaccination. Furthermore, splenic cDCs from DTPw immunised mice had altered chromatin accessibility at loci involved in immunity and metabolism, suggesting that these changes were epigenetically mediated. Interestingly, changing the order in which the BCG and DTPw vaccines were co-administered to mice altered subsequent trained immune responses. Given these differences in trained immunity, we also assessed whether administration of these vaccines altered susceptibility to sepsis in two different mouse models. Immunisation with either BCG or a DTPw-containing vaccine prior to the induction of sepsis did not significantly alter survival. Further studies are now needed to more fully investigate the potential consequences of DTPw induced trained immunity in different contexts and to assess whether other non-live vaccines also induce similar changes.  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