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   21233篇
  免费   1376篇
  国内免费   97篇
耳鼻咽喉   223篇
儿科学   556篇
妇产科学   432篇
基础医学   3332篇
口腔科学   532篇
临床医学   2077篇
内科学   4651篇
皮肤病学   531篇
神经病学   2488篇
特种医学   626篇
外科学   1803篇
综合类   109篇
一般理论   13篇
预防医学   1840篇
眼科学   417篇
药学   1336篇
中国医学   78篇
肿瘤学   1662篇
  2024年   36篇
  2023年   208篇
  2022年   410篇
  2021年   693篇
  2020年   465篇
  2019年   657篇
  2018年   697篇
  2017年   532篇
  2016年   631篇
  2015年   742篇
  2014年   881篇
  2013年   1097篇
  2012年   1768篇
  2011年   1884篇
  2010年   1001篇
  2009年   905篇
  2008年   1479篇
  2007年   1478篇
  2006年   1391篇
  2005年   1304篇
  2004年   1206篇
  2003年   1085篇
  2002年   926篇
  2001年   113篇
  2000年   73篇
  1999年   117篇
  1998年   180篇
  1997年   154篇
  1996年   111篇
  1995年   87篇
  1994年   68篇
  1993年   48篇
  1992年   31篇
  1991年   22篇
  1990年   34篇
  1989年   21篇
  1988年   15篇
  1987年   18篇
  1986年   7篇
  1985年   11篇
  1984年   12篇
  1983年   14篇
  1982年   11篇
  1981年   9篇
  1980年   15篇
  1979年   9篇
  1978年   7篇
  1977年   8篇
  1975年   6篇
  1973年   7篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
941.
Aims

We aimed to analyze prevalence and predictors of NOAC off-label under-dosing in AF patients before and after the index stroke.

Methods

The post hoc analysis included 1080 patients of the investigator-initiated, multicenter prospective Berlin Atrial Fibrillation Registry, designed to analyze medical stroke prevention in AF patients after acute ischemic stroke.

Results

At stroke onset, an off-label daily dose was prescribed in 61 (25.5%) of 239 NOAC patients with known AF and CHA2DS2-VASc score ≥ 1, of which 52 (21.8%) patients were under-dosed. Under-dosing was associated with age ≥ 80 years in patients on rivaroxaban [OR 2.90, 95% CI 1.05–7.9, P = 0.04; n = 29] or apixaban [OR 3.24, 95% CI 1.04–10.1, P = 0.04; n = 22]. At hospital discharge after the index stroke, NOAC off-label dose on admission was continued in 30 (49.2%) of 61 patients. Overall, 79 (13.7%) of 708 patients prescribed a NOAC at hospital discharge received an off-label dose, of whom 75 (10.6%) patients were under-dosed. Rivaroxaban under-dosing at discharge was associated with age ≥ 80 years [OR 3.49, 95% CI 1.24–9.84, P = 0.02; n = 19]; apixaban under-dosing with body weight ≤ 60 kg [OR 0.06, 95% CI 0.01–0.47, P < 0.01; n = 56], CHA2DS2-VASc score [OR per point 1.47, 95% CI 1.08–2.00, P = 0.01], and HAS-BLED score [OR per point 1.91, 95% CI 1.28–2.84, P < 0.01].

Conclusion

At stroke onset, off-label dosing was present in one out of four, and under-dosing in one out of five NOAC patients. Under-dosing of rivaroxaban or apixaban was related to old age. In-hospital treatment after stroke reduced off-label NOAC dosing, but one out of ten NOAC patients was under-dosed at discharge.

Clinical trial registration

NCT02306824.

  相似文献   
942.
Posttraumatic stress disorder (PTSD) is associated with an enhanced susceptibility to various somatic diseases. However, the exact mechanisms linking traumatic stress to subsequent physical health problems have remained unclear. This study investigated peripheral T lymphocyte differentiation subsets in 19 individuals with war and torture related PTSD compared to 27 non-PTSD controls (n = 14 trauma-exposed controls; n = 13 non-exposed controls). Peripheral T cell subpopulations were classified by their characteristic expression of the lineage markers CD45RA and CCR7 into: naïve (CD45RA+ CCR7+), central memory (TCM: CD45RA? CCR7+) and effector memory (TEM: CD45RA? CCR7? and TEMRA: CD45RA? CCR7?) cells. Furthermore, we analyzed regulatory T cells (CD4+CD25+FoxP3+) and ex vivo proliferation responses of peripheral blood mononuclear cells after stimulation with anti-CD3 monoclonal antibody. Results show that the proportion of naïve CD8+ T lymphocytes was reduced by 32% (p = 0.01), whereas the proportions of CD3+ central (p = 0.02) and effector (p = 0.01) memory T lymphocytes were significantly enhanced (+22% and +34%, respectively) in PTSD patients compared to non-PTSD individuals. To a smaller extent, this effect was also observed in trauma-exposed non-PTSD individuals, indicating a cumulative effect of traumatic stress on T cell distribution. Moreover, PTSD patients displayed a 48% reduction in the proportion of regulatory T cells (p < 0.001). Functionally, these alterations were accompanied by a significantly enhanced (+34%) ex vivo proliferation of anti-CD3 stimulated T cells (p = 0.05). The profoundly altered composition of the peripheral T cell compartment might cause a state of compromised immune responsiveness, which may explain why PTSD patients show an increased susceptibility to infections, and inflammatory and autoimmune diseases.  相似文献   
943.
The aim of this study was to compare the results of the day-to-day self-evaluation of sleep quality by sleep logs with Parkinson’s disease sleep scale (PDSS) in Parkinson’s disease (PD) patients. Actigraphy was used as an independent analysis of nighttime activity interfering with sleep. A total of 71 idiopathic PD patients and 21 age- and sex-matched normal individuals lacking any type of sleep disturbance were recruited. Sleep was evaluated by PDSS, 7-d sleep log and actigraphy. Sleep logs and PDSS showed reduced sleep quality and daytime somnolence scores in moderate/severe PD patients as compared to healthy controls. Significant correlations were found between sleep quality in sleep logs and all domains of PDSS sleep quality, except for the presence of nocturia, which correlated with nocturnal activity. PD severity and depression were the only predictors of reduced sleep quality. The retrospective and day-to-day sleep self-evaluations were coincident. Reduced sleep quality was related to increased PD severity and depression scores.  相似文献   
944.
CD4+ CD25+ regulatory T cells (Tregs) strongly influence the early and late autoimmune responses to meiotic germ cell antigens (MGCA) and the gonadal immunopathology in vasectomized mice. This is supported by the published and recently acquired information presented here. Within 24 h of unilateral vasectomy (uni-vx) the ipsilateral epididymis undergoes epithelial cell apoptosis followed by necrosis, severe inflammation, and granuloma formation. Unexpectedly, vasectomy alone induced MGCA-specific tolerance. In contrast, uni-vx plus simultaneous Treg depletion resulted in MGCA-specific autoimmune response and bilateral autoimmune orchitis. Both tolerance and autoimmunity were strictly linked to the early epididymal injury. We now discovered that testicular autoimmunity in uni-vx mice did not occur when Treg depletion was delayed by one week. Remarkably, this delayed Treg depletion also prevented tolerance induction. Therefore, tolerance depends on a rapid de novo Treg response to MGCA exposed after vasectomy. Moreover, tolerance was blunted in mice genetically deficient in PD-1 ligand, suggesting the involvement of induced Treg. We conclude that pre-existing natural Treg prevents post-vasectomy autoimmunity, whereas vasectomy-induced Treg maintains post-vasectomy tolerance. We further discovered that vasectomized mice were still resistant to autoimmune orchitis induction for at least 12–16 months; thus, tolerance is long-lasting. Although significant sperm autoantibodies of low titers became detectable in uni-vx mice at 7 months, the antibody titers fluctuated over time, suggesting a dynamic “balance” between the autoimmune and tolerance states. Finally, we observed severe epididymal fibrosis and hypo-spermatogenesis at 12 months after uni-vx: findings of highly critical clinical significance.  相似文献   
945.

Objective

Pregnancies complicated by intrauterine growth restriction (IUGR) are at increased risk for neonatal morbidity and mortality. The Dutch nationwide disproportionate intrauterine growth intervention trial at term (DIGITAT trial) showed that induction of labour and expectant monitoring were comparable with respect to composite adverse neonatal outcome and operative delivery. In this study we compare the costs of both strategies.

Study design

A cost analysis was performed alongside the DIGITAT trial, which was a randomized controlled trial in which 650 women with a singleton pregnancy with suspected IUGR beyond 36 weeks of pregnancy were allocated to induction or expectant management. Resource utilization was documented by specific items in the case report forms. Unit costs for clinical resources were calculated from the financial reports of participating hospitals. For primary care costs Dutch standardized prices were used. All costs are presented in Euros converted to the year 2009.

Results

Antepartum expectant monitoring generated more costs, mainly due to longer antepartum maternal stays in hospital. During delivery and the postpartum stage, induction generated more direct medical costs, due to longer stay in the labour room and longer duration of neonatal high care/medium care admissions. From a health care perspective, both strategies generated comparable costs: on average €7106 per patient for the induction group (N = 321) and €6995 for the expectant management group (N = 329) with a cost difference of €111 (95%CI: €−1296 to 1641).

Conclusion

Induction of labour and expectant monitoring in IUGR at term have comparable outcomes immediately after birth in terms of obstetrical outcomes, maternal quality of life and costs. Costs are lower, however, in the expectant monitoring group before 38 weeks of gestation and costs are lower in the induction of labour group after 38 weeks of gestation. So if induction of labour is considered to pre-empt possible stillbirth in suspected IUGR, it is reasonable to delay until 38 weeks, with watchful monitoring.  相似文献   
946.

The possible uniqueness of social stimuli constitutes a key topic for cognitive neuroscience. Growing evidence highlights graded contributions to their semantic processing by the anterior temporal lobe (ATL), where the omni-category response displayed by its ventrolateral sector might reflect the integration of information relayed from other regions. Among these, the superior polar ATL was specifically associated with representing social concepts. However, most previous studies neglected the close relationship between social and emotional semantic features, which might confound interpreting the degree of overlap vs. specificity of social and emotional conceptual processing. We addressed this issue via two activation-likelihood-estimation meta-analyses of neuroimaging studies reporting brain structures associated with processing social or emotional concepts. Alongside a common involvement of the ventromedial prefrontal cortex, we found social and emotional concepts to be specifically associated with lateral temporal areas (including the superior polar ATL) and the amygdala, respectively. These results support the specialization of distinct sectors of the fronto-temporo-limbic circuitry for processing social vs. emotional concepts, and the integration of their output in medial prefrontal regions underlying the regulation of social behavior. These results pave the way for further studies addressing the neural bases of conceptual knowledge, its impairment after fronto-temporal brain damage, and the effect of rehabilitative interventions targeting its main functional modules.

  相似文献   
947.
Evidence indicates that experience-dependent cortical plasticity underlies post-stroke motor recovery of the impaired upper extremity. Motor skill learning in neurologically intact individuals is thought to involve the primary motor cortex, and the majority of studies in the animal literature have studied changes in the primary sensorimotor cortex with motor rehabilitation. Whether changes in engagement in the sensorimotor cortex occur in humans after stroke currently is an area of much interest. The present study conducted a meta-analysis on stroke studies examining changes in neural representations following therapy specifically targeting the upper extremity to determine if rehabilitation-related motor recovery is associated with neural plasticity in the sensorimotor cortex of the lesioned hemisphere. Twenty-eight studies investigating upper extremity neural representations (e.g., TMS, fMRI, PET, or SPECT) were identified, and 13 met inclusion criteria as upper extremity intervention training studies. Common outcome variables representing changes in the primary motor and sensorimotor cortices were used in calculating standardized effect sizes for each study. The primary fixed effects model meta-analysis revealed a large overall effect size (ES=0.84, S.D.=0.15, 95% CI=0.76-0.93). Moreover, a fail-safe analysis indicated that 42 null effect studies would be necessary to lower the overall effect size to an insignificant level. These results indicate that neural changes in the sensorimotor cortex of the lesioned hemisphere accompany functional paretic upper extremity motor gains achieved with targeted rehabilitation interventions.  相似文献   
948.
BackgroundGenetic variation in the guidance cue DCC gene is linked to psychopathologies involving dysfunction in the prefrontal cortex. We created an expression-based polygenic risk score (ePRS) based on the DCC coexpression gene network in the prefrontal cortex, hypothesizing that it would be associated with individual differences in total brain volume.MethodsWe filtered single nucleotide polymorphisms (SNPs) from genes coexpressed with DCC in the prefrontal cortex obtained from an adult postmortem donors database (BrainEAC) for genes enriched in children 1.5 to 11 years old (BrainSpan). The SNPs were weighted by their effect size in predicting gene expression in the prefrontal cortex, multiplied by their allele number based on an individual’s genotype data, and then summarized into an ePRS. We evaluated associations between the DCC ePRS and total brain volume in children in 2 community-based cohorts: the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) and University of California, Irvine (UCI) projects. For comparison, we calculated a conventional PRS based on a genome-wide association study of total brain volume.ResultsHigher ePRS was associated with higher total brain volume in children 8 to 10 years old (β = 0.212, p = 0.043; n = 88). The conventional PRS at several different thresholds did not predict total brain volume in this cohort. A replication analysis in an independent cohort of newborns from the UCI study showed an association between the ePRS and newborn total brain volume (β = 0.101, p = 0.048; n = 80). The genes included in the ePRS demonstrated high levels of coexpression throughout the lifespan and are primarily involved in regulating cellular function.LimitationsThe relatively small sample size and age differences between the main and replication cohorts were limitations.ConclusionOur findings suggest that the DCC coexpression network in the prefrontal cortex is critically involved in whole brain development during the first decade of life. Genes comprising the ePRS are involved in gene translation control and cell adhesion, and their expression in the prefrontal cortex at different stages of life provides a snapshot of their dynamic recruitment.  相似文献   
949.
To validate a simultaneous analysis tool for the brain and cervical cord embedded in the statistical parametric mapping (SPM) framework, we compared trauma‐induced macro‐ and microstructural changes in spinal cord injury (SCI) patients to controls. The findings were compared with results obtained from existing processing tools that assess the brain and spinal cord separately. A probabilistic brain‐spinal cord template (BSC) was generated using a generative semi‐supervised modelling approach. The template was incorporated into the pre‐processing pipeline of voxel‐based morphometry and voxel‐based quantification analyses in SPM. This approach was validated on T1‐weighted scans and multiparameter maps, by assessing trauma‐induced changes in SCI patients relative to controls and comparing the findings with the outcome from existing analytical tools. Consistency of the MRI measures was assessed using intraclass correlation coefficients (ICC). The SPM approach using the BSC template revealed trauma‐induced changes across the sensorimotor system in the cord and brain in SCI patients. These changes were confirmed with established approaches covering brain or cord, separately. The ICC in the brain was high within regions of interest, such as the sensorimotor cortices, corticospinal tracts and thalamus. The simultaneous voxel‐wise analysis of brain and cervical spinal cord was performed in a unique SPM‐based framework incorporating pre‐processing and statistical analysis in the same environment. Validation based on a SCI cohort demonstrated that the new processing approach based on the brain and cord is comparable to available processing tools, while offering the advantage of performing the analysis simultaneously across the neuraxis.  相似文献   
950.
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