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   9834篇
  免费   558篇
  国内免费   87篇
耳鼻咽喉   163篇
儿科学   107篇
妇产科学   116篇
基础医学   1554篇
口腔科学   220篇
临床医学   700篇
内科学   1951篇
皮肤病学   361篇
神经病学   619篇
特种医学   515篇
外科学   1480篇
综合类   36篇
一般理论   3篇
预防医学   385篇
眼科学   207篇
药学   852篇
中国医学   143篇
肿瘤学   1067篇
  2024年   10篇
  2023年   81篇
  2022年   235篇
  2021年   415篇
  2020年   149篇
  2019年   265篇
  2018年   301篇
  2017年   233篇
  2016年   378篇
  2015年   462篇
  2014年   541篇
  2013年   557篇
  2012年   891篇
  2011年   796篇
  2010年   478篇
  2009年   388篇
  2008年   575篇
  2007年   521篇
  2006年   473篇
  2005年   462篇
  2004年   379篇
  2003年   322篇
  2002年   249篇
  2001年   258篇
  2000年   218篇
  1999年   154篇
  1998年   71篇
  1997年   54篇
  1996年   41篇
  1995年   50篇
  1994年   37篇
  1993年   31篇
  1992年   72篇
  1991年   52篇
  1990年   40篇
  1989年   36篇
  1988年   37篇
  1987年   31篇
  1986年   25篇
  1985年   23篇
  1984年   9篇
  1983年   9篇
  1981年   6篇
  1980年   6篇
  1979年   8篇
  1978年   5篇
  1976年   7篇
  1974年   4篇
  1973年   6篇
  1968年   6篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
41.
Abstinence from prolonged psychostimulant use prompts stimulant withdrawal syndrome. Molecular adaptations within the dorsal striatum have been considered the main hallmark of stimulant abstinence. Here we explored striatal miRNA–target interaction and its impact on circulating miRNA marker as well as behavioral dysfunctions in methamphetamine (MA) abstinence. We conducted miRNA sequencing and profiling in the nonhuman primate model of MA abstinence, followed by miRNA qPCR, LC–MS/MS proteomics, immunoassays, and behavior tests in mice. In nonhuman primates, MA abstinence triggered a lasting upregulation of miR-137 in the dorsal striatum but a simultaneous downregulation of circulating miR-137. In mice, aberrant increase in striatal miR-137-dependent inhibition of SYNCRIP essentially mediated the MA abstinence-induced reduction of circulating miR-137. Pathway modeling through experimental deduction illustrated that the MA abstinence-mediated downregulation of circulating miR-137 was caused by reduction of SYNCRIP-dependent miRNA sorting into the exosomes in the dorsal striatum. Furthermore, diminished SYNCRIP in the dorsal striatum was necessary for MA abstinence-induced behavioral bias towards egocentric spatial learning. Taken together, our data revealed circulating miR-137 as a potential blood-based marker that could reflect MA abstinence-dependent changes in striatal miR-137/SYNCRIP axis, and striatal SYNCRIP as a potential therapeutic target for striatum-associated cognitive dysfunction by MA withdrawal syndrome.  相似文献   
42.
ContextThe sleep-promoting activity of Nelumbo nucifera Gaertn. (Nymphaeaceae) alkaloids in leaves or seeds are well known. However, the sleep-promoting activity of the lotus rhizome (LE), which is used mainly as food, has not yet been evaluated.ObjectiveWe investigated the sleep-promoting activity of LE water extract.Materials and methodsInstitute of Cancer Research (ICR) mice (n = 8) were subject to a pentobarbital-induced sleep test to assess changes in sleep latency and duration following the administration of LE (80–150 mg/kg). In addition, electroencephalography analysis was performed to determine the sleep quality after LE treatment as well as the sleep recovery effect of LE using a caffeine-induced insomnia SD rat model. Real-time PCR and western blot analysis were performed to investigate the expression of neurotransmitter receptors, and the GABAA receptor antagonists were used for receptor binding analysis.ResultsAn oral administration of 150 mg/kg LE significantly increased sleep duration by 24% compared to the control. Furthermore, LE increased nonrapid eye movement (NREM) sleep by increasing theta and delta powers. In the insomnia model, LE increased sleep time by increasing NREM sleep. Moreover, treatment with picrotoxin and flumazenil decreased the sleep time by 33% and 23%, respectively, indicating an involvement of the GABAA receptor in the sleep-enhancing activity of LE. The expression of GABAA receptors and the concentration of GABA in the brain were increased by LE.Discussion and conclusionsThe results suggest that the sleep-promoting activity of LE was via the GABAA receptor. Collectively, these data show that LE may promote sleep.  相似文献   
43.
BackgroundThis study investigated whether the empirical dietary inflammatory index (eDII) score is associated with the inflammatory burden as well as the depressive status in patients with antineutrophil cytoplasmic antibody‐associated vasculitis (AAV).MethodsEighty‐four patients with AAV participated in this study. Birmingham vasculitis activity score (BVAS) and short‐form 36‐item Health Survey mental component summary (SF‐36 MCS) were considered as indices assessing the inflammatory burden and depressive status, respectively. The eDII includes 16 food components and consists of three groups: −9 to −2, the low eDII group; −1 to +1, the moderate eDII group; and +2 to +10, the high eDII group. Furthermore, the lower eDII group includes both the low and moderate eDII groups.ResultsThe median age was 64.5 years (36 men). The eDII scores inversely correlated with SF‐36 MCS (r = −0.298, p = 0.006) but not with BVAS. SF‐36 MCS significantly differ between the lower and higher eDII groups (69.7 vs. 56.7, p = 0.016), but not among the low, moderate and high eDII groups. Additionally, when patients with AAV were divided into two groups according to the upper limit of the lowest tertile of SF‐36 MCS of 55.31, patients in the higher eDII group exhibited a significantly higher risk for the lowest tertile of SF‐36 MCS than those in the lower eDII group (RR 3.000).ConclusionWe demonstrated for the first time that the eDII could predict the depressive status by estimating SF‐36 MCS without utilising K‐CESD‐R ≥ 16 in patients with AAV.  相似文献   
44.
Sex impacts the development of the brain and cognition differently across individuals. However, the literature on brain sex dimorphism in humans is mixed. We aim to investigate the biological underpinnings of the individual variability of sexual dimorphism in the brain and its impact on cognitive performance. To this end, we tested whether the individual difference in brain sex would be linked to that in cognitive performance that is influenced by genetic factors in prepubertal children (N = 9,658, ages 9–10 years old; the Adolescent Brain Cognitive Development study). To capture the interindividual variability of the brain, we estimated the probability of being male or female based on the brain morphometry and connectivity features using machine learning (herein called a brain sex score). The models accurately classified the biological sex with a test ROC–AUC of 93.32%. As a result, a greater brain sex score correlated significantly with greater intelligence (p fdr < .001, ηp2 = .011–.034; adjusted for covariates) and higher cognitive genome‐wide polygenic scores (GPSs) (p fdr < .001, ηp2 < .005). Structural equation models revealed that the GPS‐intelligence association was significantly modulated by the brain sex score, such that a brain with a higher maleness score (or a lower femaleness score) mediated a positive GPS effect on intelligence (indirect effects = .006–.009; p = .002–.022; sex‐stratified analysis). The finding of the sex modulatory effect on the gene–brain–cognition relationship presents a likely biological pathway to the individual and sex differences in the brain and cognitive performance in preadolescence.  相似文献   
45.
BackgroundThe rapid urease test (RUT) is a major diagnostic tool for detecting Helicobacter pylori infection. This study aimed to establish an objective method for measuring the color changes in the RUT kit to improve the test’s diagnostic accuracy.MethodsA UV-visible spectrophotometer was selected as the colorimeter; experiments were conducted in three stages to objectively identify the color changes in the RUT kit.ResultsFirst, the urea broth solution showed an identifiable color change from yellow to red as the pH increased by 0.2. The largest transmittance difference detected using the UV-visible spectrophotometer was observed at a 590-nm wavelength. Second, the commercialized RUT kit also showed a gradual color change according to the pH change detected using the UV-visible spectrophotometer. Third, 13 cases of negative RUT results with a biopsy specimen and 16 of positive RUT results were collected. The transmittance detected using the UV-visible spectrophotometer showed a clear division between the positive and negative RUT groups; the largest difference was observed at a 559-nm wavelength. The lowest transmittance in the negative RUT group was 64, while the highest in the positive RUT group was 56, at the 559-nm wavelength. The UV-visible spectrophotometry reading showed a consistency of 92.7% compared with that of manual reading.ConclusionA transmittance of 60 at a 559-nm wavelength detected using UV-visible spectrophotometer can be used as a cutoff value for interpreting RUT results; this will help develop an automatic RUT kit reader with a high accuracy.  相似文献   
46.
Phloroglucinol (PG), a polyphenol compound of Eckloniacava known as brown algae abundant in Jeju island, has been proposed to exert the antioxidative and cytoprotective effects against oxidative stress. In this study, we confirmed that PG protected mice from damages caused by ionizing radiation and investigated its protection mechanism in detail. The result showed that PG increased the viability of splenocytes without cytotoxicity. Also, PG significantly enhanced the proliferation of splenocytes by limiting the increment of sub-G1 DNA contents via the inhibition of reactive oxygen species production in 2 Gy-irradiated splenocytes. In addition, PG significantly decreased DNA damage and the number of apoptotic fragments in lymphocytes against oxidative stress. Also, PG increased the counts of endogenous spleen CFUs, compared with only ionizing radiation-irradiated mice. These results demonstrate the multi-faceted protection mechanisms of PG in mice against oxidative stress caused by ionizing radiation, providing the benefit of inhibiting apoptosis and strengthening hematopoiesis.  相似文献   
47.
48.
Efforts have been made for sustainable development of adsorbents to purify organic contaminants from wastewater. In this study, a MIL-100(Fe) based textile that acts as a reusable adsorbent and photocatalytic agent was developed by synthesizing MIL-100(Fe) onto a cotton fabric by the layer-by-layer (LBL) process using water-based solutions. As the number of LBL cycles increased, the add-on''s of MIL-100(Fe) showed a drastic increase up to 8 cycles, then showed gradual increases with further treatments. The overall adsorption performance was enhanced with the increased MIL-100(Fe) add-on''s, but the specific adsorption efficiency per unit mass of MIL-100(Fe) was reduced as the LBL cycles increased, implying the reduced average adsorption efficiency with a thicker coating. To examine the reusability of the adsorbent, desorption efficiency of RhB was measured. The desorption after the first-time adsorption was not efficient due to the strong binding inside the pores. For the later cycles of adsorption–desorption, desorption occurred more efficiently, probably because RhB molecules were adhered mostly at the outer surface of the MOF layer. Simultaneously, MIL-100(Fe)@cotton demonstrated the photocatalytic degradation performance against RhB in the presence of H2O2 by the Fenton reaction. With the combined effect of adsorption and photodegradation, the developed fabric attained 96% removal efficiency for RhB dissolved in water. This study demonstrates an environmentally responsible process of developing a MIL-100(Fe) coated fabric that is readily available for effective removal of organic foulants in water. This fabrication method can be applied as a scalable manufacturing of metal–organic framework-based photocatalytic adsorbent textiles.

A MIL-100(Fe)-based water purifying textile that functions by dual action of adsorption and photocatalytic activity is designed via a layer-by-layer process without using toxic organic solvents.  相似文献   
49.
BackgroundThe Korea National Antimicrobial Use Analysis System (KONAS), a benchmarking system for antimicrobial use in hospitals, provides Korean Standardized Antimicrobial Administration Ratio (K-SAAR) for benchmarking. This article describes K-SAAR predictive models to enhance the understanding of K-SAAR, an important benchmarking strategy for antimicrobial usage in KONAS.MethodsWe obtained medical insurance claims data for all hospitalized patients aged ≥ 28 days in all secondary and tertiary care hospitals in South Korea (n = 347) from January 2019 to December 2019 from the Health Insurance Review & Assessment Service. Modeling was performed to derive a prediction value for antimicrobial use in each institution, which corresponded to the denominator value for calculating K-SAAR. The prediction values of antimicrobial use were modeled separately for each category, for all inpatients and adult patients (aged ≥ 15 years), using stepwise negative binomial regression.ResultsThe final models for each antimicrobial category were adjusted for different significant risk factors. In the K-SAAR models of all aged patients as well as adult patients, most antimicrobial categories included the number of hospital beds and the number of operations as significant factors, while some antimicrobial categories included mean age for inpatients, hospital type, and the number of patients transferred from other hospitals as significant factors.ConclusionWe developed a model to predict antimicrobial use rates in Korean hospitals, and the model was used as the denominator of the K-SAAR.  相似文献   
50.
BackgroundPityriasis rosea (PR) is a papulosquamous eruption with generally unknown origin but suspected to be related to viral etiologies. The clinicopathological spectrum of several disorders with viral etiologies has been altered after the coronavirus disease 2019 (COVID-19) pandemic. The author group could experience coherent histological alterations in PR after the COVID-19 pandemic. This study aimed to investigate how the clinicopathological findings of PR were changed after the COVID-19 pandemic.MethodsPatients (n = 11) diagnosed with PR based on the clinical manifestations and skin biopsies between February 2018 and October 2019 and 11 patients in February 2020 and October 2021 were retrospectively analyzed by investigating the medical records.ResultsThe patients with PR during the COVID-19 pandemic demonstrated statistically significant histopathological alterations from classic brisk and dense infiltration pattern to dormant and sparse infiltration and psoriasiform-dominant patterns (P = 0.019). PR was associated with more frequent pruritus during the pandemic period (P = 0.027).ConclusionIn conclusion, PR demonstrated a significant histopathological alteration with more frequent pruritus during the COVID-19 pandemic. The comparative results about clinicopathological findings of PR will provide a useful reference for dermatologists in the diagnostic process of PR in the COVID-19 pandemic.  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