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   45952篇
  免费   4936篇
  国内免费   1799篇
耳鼻咽喉   367篇
儿科学   361篇
妇产科学   418篇
基础医学   5804篇
口腔科学   1332篇
临床医学   4374篇
内科学   4877篇
皮肤病学   409篇
神经病学   3310篇
特种医学   1560篇
外国民族医学   1篇
外科学   4182篇
综合类   7982篇
现状与发展   4篇
预防医学   6817篇
眼科学   774篇
药学   5102篇
  73篇
中国医学   2827篇
肿瘤学   2113篇
  2024年   176篇
  2023年   957篇
  2022年   1412篇
  2021年   2448篇
  2020年   2083篇
  2019年   1625篇
  2018年   1582篇
  2017年   1770篇
  2016年   1655篇
  2015年   1812篇
  2014年   2984篇
  2013年   3438篇
  2012年   2774篇
  2011年   3163篇
  2010年   2428篇
  2009年   2534篇
  2008年   2512篇
  2007年   2504篇
  2006年   2126篇
  2005年   1902篇
  2004年   1512篇
  2003年   1328篇
  2002年   1001篇
  2001年   894篇
  2000年   827篇
  1999年   698篇
  1998年   541篇
  1997年   506篇
  1996年   427篇
  1995年   394篇
  1994年   374篇
  1993年   285篇
  1992年   278篇
  1991年   210篇
  1990年   216篇
  1989年   181篇
  1988年   150篇
  1987年   148篇
  1986年   106篇
  1985年   150篇
  1984年   111篇
  1983年   71篇
  1982年   75篇
  1981年   70篇
  1980年   60篇
  1979年   53篇
  1978年   34篇
  1977年   28篇
  1976年   27篇
  1974年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Understanding the constraints, including biological ones, that may influence mathematical development is of great importance because math ability is a key predictor of career success, income and even psychological well-being. While research in developmental cognitive neuroscience of mathematics has extensively studied the key functional regions for processing numbers, particularly the horizontal segment of intraparietal sulcus (HIPS), few studies have investigated the effects of early cerebral constraints on later mathematical abilities. In this pre-registered study, we investigated whether variability of the sulcal pattern of the HIPS, a qualitative feature of the brain determined in-utero and not affected by brain maturation and learning, accounts for individual difference in symbolic and non-symbolic number abilities. Seventy-seven typically developing school-aged children and 21 young adults participated in our study. We found that the HIPS sulcal pattern, (a) explains part of the variance in participant’s symbolic number comparison and math fluency abilities, and (b) that this association between HIPS sulcal pattern and symbolic number abilities was found to be stable from childhood to young adulthood. However, (c) we did not find an association between participant’s non-symbolic number abilities and HIPS sulcal morphology. Our findings suggest that early cerebral constraints may influence individual difference in math abilities, in addition to the well-established neuroplastic factors.  相似文献   
992.
《Brain stimulation》2021,14(3):643-651
BackgroundEvidence suggests that schizophrenia constitutes a neurodevelopmental disorder, characterized by a gradual emergence of behavioral and neurobiological abnormalities over time. Therefore, applying early interventions to prevent later manifestation of symptoms is appealing.ObjectiveThis review focuses on the use of cortical neuromodulation in schizophrenia and its potential as a preventive treatment approach. We present clinical and preclinical findings investigating the use of neuromodulation in schizophrenia, including the current research focusing on cortical non-invasive stimulation and its possibility as a future preventive treatment.MethodsWe performed a search in Medline (PubMed) in September 2020 using a combination of relevant medical subject headings (MeSH) and text words. The search included human and preclinical trials as well as existing systematic reviews and meta-analysis. There were no restrictions on language or the date of publication.ResultsNeurodevelopmental animal models may be used to investigate how the disease progresses and thus which brain areas ideally should be targeted at a given time point. Here, abnormalities of the prefrontal cortex have been often identified as an early and persistent impairment in schizophrenia. Currently there is insufficient evidence to either support or refute the use of neuromodulation to the cortex in adult patients with already manifested symptoms. However, preclinical results show that early non-invasive neuromodulation to the prefrontal cortex of adolescent animals, sufficiently prevents later psychosis-relevant abnormalities in adulthood. This points to the promising potential of cortical non-invasive neuromodulation as a preventive treatment when applied early in the course of the disease.ConclusionPreclinical translational-oriented findings indicate, that neuromodulation to cortical areas offers the possibility of targeting early neuropathology and through this diminish the progression of a later schizophrenic profile. Further studies are needed to investigate whether such early cortical stimulation may serve as a future preventive treatment in schizophrenia.  相似文献   
993.
ObjectiveNeuropsychiatric lupus (NPSLE), a manifestation of the autoimmune disease systemic lupus erythematosus (SLE), is characterized by psychiatric symptoms including anxiety and depression and upregulated autoantibodies. The B6.Nba2 spontaneous mouse model develops SLE, but has not previously been tested for NPSLE.MethodsWe investigated the NPSLE phenotype in male and female B6.Nba2 mice (n = 12 each) and age- and sex-matched B6 controls (n = 10 each) via behavioral assessments for anxiety, depression, and memory deficits. Serum anti-dsDNA, anti-nRNP, anti-DWEYS peptide reactive IgG autoantibody levels and soluble TWEAK levels were determined by ELISA. Hippocampal regions were stained for activated microglia and neurons.ResultsBoth male and female B6.Nba2 mice showed elevated anti-dsDNA IgG, anti-nRNP IgG and anti-DWEYS reactive antibodies, elevated serum soluble TWEAK levels, and a strong anxiety and depression phenotype (p < 0.05–0.0001). Male B6.Nba2 mice developed this phenotype at a slightly older age than females. Female B6.Nba2 mice displayed reduced numbers of neurons in the hippocampal region compared to female B6 controls (p < 0.05).ConclusionThe B6.Nba2 mouse model recapitulates many known NPSLE phenotypes, making it a promising model to investigate the development of NPSLE in the context of SLE.  相似文献   
994.
995.
996.
997.
Abstract

Treatment of chronic skin wound such as diabetic ulcers, burns, pressure wounds are challenging problems in the medical area. The aim of this study was to design a bilayer skin equivalent mimicking the natural one to be used as a tissue engineered skin graft for use in the treatments of problematic wounds, and also as a model to be used in research related to skin, such as determination of the efficacy of transdermal bioactive agents on skin cells and treatment of acute skin damages that require immediate response. In this study, the top two layers of the skin were mimicked by producing a multilayer construct combining two different porous polymeric scaffolds: as the dermis layer a sodium carboxymethyl cellulose (NaCMC) hydrogel on which fibroblasts were added, and as the epidermis layer collagen (Coll) or chondroitin sulfate-incorporated collagen (CollCS) on which keratinocytes were added. The bilayer construct was designed to allow cross-talk between the two cell populations in the subsequent layers and achieves paracrine signalling. It had interconnected porosity, high water content, appropriate stability and elastic moduli. Expression of vascular endothelial growth factor (VEGF), basic-fibroblast growth factor (bFGF) and Interleukin 8 (IL-8), and the production of collagen I, collagen III, laminin and transglutaminase supported the attachment and proliferation of cells on both layers of the construct. Attachment and proliferation of fibroblasts on NaCMC were lower compared to performance of keratinocyte on collagen where keratinocytes created a dense and a stratified layer similar to epidermis. The resulting constructs succesfully mimicked in vitro the natural skin tissue. They are promising as grafts for use in the treatment of deep wounds and also as models for the study of the efficacy of bioactive agents on the skin.  相似文献   
998.
Blast injuries affect millions of lives across the globe due to its traumatic after effects on the brain and the whole body. To date, military grade armour materials are designed to mitigate ballistic and shrapnel attacks but are less effective in resisting blast impacts. In order to improve blast absorption characteristics of armours, the first key step is thoroughly understands the effects of blasts on the human body itself. In the last decade, a plethora of experimental and computational work has been carried out to investigate the mechanics and pathophysiology of Traumatic Brain Injury (TBI). However, very few attempts have been made so far to study the effect of blasts on the various other parts of the body such as the sensory organs (eyes and ears), nervous system, thorax, extremities, internal organs (such as the lungs) and the skeletal system. While an experimental evaluation of blast effects on such physiological systems is difficult, developing finite element (FE) models could allow the recreation of realistic blast scenarios on full scale human models and simulate the effects. The current article reviews the state-of-the-art in computational research in blast induced whole-body injury modelling, which would not only help in identifying the areas in which further research is required, but would also be indispensable for understanding body location specific armour design criteria for improved blast injury mitigation.  相似文献   
999.
1000.
介绍数据监管的内涵,阐述加州州立理工大学图书馆数据监管需求评估项目,分析项目成果,指出该项目对国内图书馆的启示,即开展科研数据服务营销推广、数据监管培训服务、通过合作实现高质量的数据监管服务等。  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