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   11001篇
  免费   1194篇
  国内免费   492篇
耳鼻咽喉   98篇
儿科学   95篇
妇产科学   113篇
基础医学   2851篇
口腔科学   199篇
临床医学   738篇
内科学   1730篇
皮肤病学   240篇
神经病学   885篇
特种医学   480篇
外国民族医学   3篇
外科学   536篇
综合类   1446篇
现状与发展   7篇
预防医学   431篇
眼科学   183篇
药学   1277篇
  2篇
中国医学   474篇
肿瘤学   899篇
  2024年   17篇
  2023年   178篇
  2022年   246篇
  2021年   372篇
  2020年   325篇
  2019年   301篇
  2018年   284篇
  2017年   342篇
  2016年   387篇
  2015年   409篇
  2014年   611篇
  2013年   760篇
  2012年   673篇
  2011年   743篇
  2010年   696篇
  2009年   721篇
  2008年   675篇
  2007年   670篇
  2006年   639篇
  2005年   572篇
  2004年   502篇
  2003年   469篇
  2002年   408篇
  2001年   302篇
  2000年   228篇
  1999年   177篇
  1998年   149篇
  1997年   152篇
  1996年   116篇
  1995年   116篇
  1994年   87篇
  1993年   76篇
  1992年   58篇
  1991年   40篇
  1990年   24篇
  1989年   23篇
  1988年   13篇
  1987年   10篇
  1986年   14篇
  1985年   23篇
  1984年   13篇
  1983年   12篇
  1982年   9篇
  1981年   8篇
  1980年   11篇
  1979年   6篇
  1977年   2篇
  1976年   6篇
  1973年   7篇
  1972年   2篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
21.
β-arrestin1(ARRB1)作为β-arrestin(ARRB)家族成员,是一类具有多种生物学功能的细胞内支架蛋白。其参与调控G蛋白偶联受体(G protein-coupled receptor,GPCR)和非GPCR介导的信号通路。ARRB1与炎症和癌症密切相关,不仅参与炎症形成,而且通过多种方式调节炎癌转化的进程。因此对ARRB1的生物学特性及其在炎癌转化中作用的研究,将有助于揭示其对人类肿瘤进程干预的潜在价值。  相似文献   
22.
The interaction of CD47 and signal-regulatory protein alpha (SIRPα) induces “don't eat me signal”, leading suppression of phagocytosis. This signal can affect the clinical course of malignant disease. Although CD47 and SIRPα expression are associated with clinicopathological features in several neoplasms, the investigation for adult T-cell leukemia/lymphoma (ATLL) has not been well-documented. This study aimed to declare the association between CD47 and SIRPα expression and clinicopathological features in ATLL. We performed immunostaining on 73 biopsy samples and found that CD47 is primarily expressed in tumor cells, while SIRPα is expressed in non-neoplastic stromal cells. CD47 positive cases showed significantly higher FoxP3 (P = .0232) and lower CCR4 (P = .0214). SIRPα positive cases presented significantly better overall survival than SIRPα negative cases (P = .0132). SIRPα positive cases showed significantly HLA class I (P = .0062), HLA class II (P = .0133), microenvironment PD-L1 (miPD-L1) (P = .0032), and FoxP3 (P = .0229) positivity. In univariate analysis, SIRPα expression was significantly related to prognosis (Hazard ratio [HR] 0.470; 95% confidence interval [CI] 0.253-0.870; P = .0167], although multivariate analysis did not show SIPRα as an independent prognostic factor. The expression of SIRPα on stromal cells reflects activated immune surveillance mechanism in tumor microenvironment and induce good prognosis in ATLL. More detailed studies for gene expression or genomic abnormalities will disclose clinical and biological significance of the CD47 and SIRPα in ATLL.  相似文献   
23.
24.
Stopping, or inhibition, is a form of self‐control that is a core element of flexible and adaptive behavior. Its neural origins remain unclear. Some views hold that inhibition decisions reflect the aggregation of widespread and diverse pieces of information, including information arising in ostensible core reward regions (i.e., outside the canonical executive system). We recorded activity of single neurons in the orbitofrontal cortex (OFC) of macaques, a region associated with economic decisions, and whose role in inhibition is debated. Subjects performed a classic inhibition task known as the stop signal task. Ensemble decoding analyses reveal a clear firing rate pattern that distinguishes successful from failed inhibition and that begins after the stop signal and before the stop signal reaction time (SSRT). We also found a different and orthogonal ensemble pattern that distinguishes successful from failed stopping before the beginning of the trial. These signals were distinct from, and orthogonal to, value encoding, which was also observed in these neurons. The timing of the early and late signals was, respectively, consistent with the idea that neuronal activity in OFC encodes inhibition both proactively and reactively.  相似文献   
25.
摘要:目的 基于Hippo信号通路核心基因mRNA表达,探索具有补肾填精壮骨之效的金刚丸治疗去卵巢(ovariectomized,OVX)大鼠骨质疏松症的疗效机制。方法 通过OVX法建立绝经后骨质疏松症(postmenopausal osteoporosis,PMOP)大鼠模型,分正常组、假手术组、模型组、金刚丸高剂量组、金刚丸中剂量组、金刚丸低剂量组、仙灵骨葆对照组、骨化三醇对照组。灌胃12周后,通过X射线骨密度仪检测骨密度、镜下观察股骨头显微形态结构、ELISA法检测血清ALP、实时定量RT-PCR检测骨组织Mst2、Lats1、Taz mRNA表达。结果 ①与正常组比较,模型组股骨骨密度显著降低(P<0.01)、骨微结构显著破坏、血清ALP显著降低(P<0.01)、骨组织Mst2、Lats1 mRNA表达显著升高(P<0.01)、Taz mRNA表达显著降低(P<0.01);②与模型组比较,除金刚丸低剂量组外,各给药组的骨密度均显著升高(P<0.01),各给药组骨微结构破坏均得到改善、血清ALP均显著升高(P<0.01)、骨组织Mst2、Lats1 mRNA表达均显著降低(P<0.01)、Taz mRNA表达均显著升高(P<0.01),均以金刚丸高剂量组最为显著。结论 骨组织Hippo信号通路核心基因Mst2、Lats1 mRNA表达上调,Taz mRNA表达下调可能是PMOP的发病机制之一;金刚丸可能通过下调骨组织Hippo信号通路核心基因Mst2、Lats1 mRNA表达、上调Taz mRNA表达的机制,有效防治PMOP。  相似文献   
26.
27.
目的:探讨口服蛋氨酸饲料致大鼠心力衰竭模型的机制,及程序性死亡因子4(PDCD4)通路在此过程中的作用。方法:5周龄健康Wistar雄性大鼠30只,适应性喂养1周后,随机分为实验组与对照组,实验组给予3%蛋氨酸饲料喂养,对照组标准饲料喂养。12周后进行血流动力学检测,采用酶联免疫法测定血清同型半胱氨酸(HCY)及N端前脑钠肽(NT-proBNP)水平,心脏彩超进行心功能评估,病理染色明确有无细胞肥大、纤维化,Western blot检测心肌组织中PDCD4蛋白的表达。结果:3%蛋氨酸饲料喂养组HCY水平较对照组升高(均P<0.05),心脏彩超提示3%蛋氨酸饲料喂养组大鼠左室射血分数、缩短分数、室间隔厚度显著减低(均P<0.05),左室收缩末内径及舒张末内径较对照组显著增加(均P<0.05),Western blot结果显示, PDCD4蛋白表达降低(P<0.05)。结论:通过口服蛋氨酸饲料造成大鼠高HCY血症可导致大鼠出现心室重塑,并造成心功能受损,其机制可能与PDCD4信号通路的下调有关。  相似文献   
28.
The mucosal glycocalyx of the ocular surface constitutes the point of interaction between the tear film and the apical epithelial cells. Membrane-associated mucins (MAMs) are the defining molecules of the glycocalyx in all mucosal epithelia. Long recognized for their biophysical properties of hydration, lubrication, anti-adhesion and repulsion, MAMs maintain the wet ocular surface, lubricate the blink, stabilize the tear film and create a physical barrier to the outside world. However, it is increasingly appreciated that MAMs also function as cell surface receptors that transduce information from the outside to the inside of the cell. A number of excellent review articles have provided perspective on the field as it has progressed since 1987, when molecular cloning of the first MAM was reported. The current article provides an update for the ocular surface, placing it into the broad context of findings made in other organ systems, and including new genes, new protein functions and new biological roles. We discuss the epithelial tissue-equivalent with mucosal differentiation, the key model system making these advances possible. In addition, we make the first systematic comparison of MAMs in human and mouse, establishing the basis for using knockout mice for investigations with the complexity of an in vivo system. Lastly, we discuss findings from human genetics/genomics, which are providing clues to new MAM roles previously unimagined. Taken together, this information allows us to generate hypotheses for the next stage of investigation to expand our knowledge of MAM function in intracellular signaling and roles unique to the ocular surface.  相似文献   
29.
PurposeThe purpose of this study was to identify in the EPIRMEX cohort the correlations between MRI brain metrics, including diffuse excessive high signal intensities (DEHSI) obtained with an automated quantitative method and neurodevelopmental outcomes at 2 years.Materials and methodsA total of 390 very preterm infants (gestational age at birth  32 weeks) who underwent brain MRI at term equivalent age at 1.5T (n = 338) or 3T (n = 52) were prospectively included. Using a validated algorithm, automated metrics of the main brain surfaces (cortical and deep gray matter, white matter, cerebrospinal fluid) and DEHSI with three thresholds were obtained. Linear adjust regressions were performed to assess the correlation between brain metrics with the ages and stages questionnaire (ASQ) score at 2 years.ResultsBasal ganglia and thalami, cortex and white matter surfaces positively and significantly correlated with the global ASQ score. For all ASQ sub-domains, basal ganglia and thalami surfaces significantly correlated with the scores. DEHSI was present in 289 premature newborns (74%) without any correlation with the ASQ score. Metrics of DEHSI were greater at 3T than at 1.5T.ConclusionBrain MRI metrics obtained in our multicentric cohort correlate with the neurodevelopmental outcome at 2 years of age. The quantitative detection of DEHSI is not predictive of adverse outcomes. Our automated algorithm might easily provide useful predictive information in daily practice.  相似文献   
30.
IntroductionSingle cochlear implantation usually provides substantial speech intelligibility benefits but bilaterally deaf, unilaterally implanted subjects will continue to experience limitations due to the head shadow effect, like single-sided deaf individuals. In the treatment of individuals with single-sided deafness one option is contralateral routing of signal (CROS) devices, which constitute a non-surgical intervention of the second ear in unilaterally implanted individuals.MethodTwelve experienced adult cochlear implant users with Naída Q70 processor and the CROS device used in combination participated in the study. For the study 3 conditions were provided: cochlear implant only, omnidirectional microphone mode (CROS deactivated); cochlear implant plus CROS activated, omnidirectional microphone mode and cochlear implant plus CROS activated, UltraZoom mode. Speech reception thresholds were determined in quiet and noise. Subjective feedback regarding the practical usability of the CROS device and the perceived benefit were collected.ResultsThere was a 27.6% improvement in speech understanding in quiet and 32.5% improvement in noise when CROS device was activated. Using advanced directional microphones, a statistically significant benefit of 35% was obtained. The responses to the questionnaires revealed that the subjects perceived benefit in their everyday lives when using the CROS device with their cochlear implants.ConclusionThe investigated CROS device used by unilateral CI recipients in cases where bilateral implantation is not an option provides both subjective and objective speech recognition benefit when the signal is directed to the CROS device. Unfavourable conditions where speech is presented from the cochlear implant side and noise from the CROS side or diffusely were not included in this evaluation since the CROS device adds additional noise and performance is expected to decrease as has previously been shown.  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