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   7182篇
  免费   589篇
  国内免费   42篇
耳鼻咽喉   72篇
儿科学   216篇
妇产科学   167篇
基础医学   1165篇
口腔科学   202篇
临床医学   741篇
内科学   1362篇
皮肤病学   220篇
神经病学   733篇
特种医学   207篇
外科学   653篇
综合类   114篇
一般理论   5篇
预防医学   624篇
眼科学   192篇
药学   612篇
中国医学   44篇
肿瘤学   484篇
  2023年   50篇
  2022年   134篇
  2021年   234篇
  2020年   121篇
  2019年   190篇
  2018年   165篇
  2017年   134篇
  2016年   179篇
  2015年   182篇
  2014年   266篇
  2013年   356篇
  2012年   551篇
  2011年   581篇
  2010年   322篇
  2009年   237篇
  2008年   459篇
  2007年   467篇
  2006年   427篇
  2005年   399篇
  2004年   363篇
  2003年   344篇
  2002年   293篇
  2001年   64篇
  2000年   49篇
  1999年   64篇
  1998年   69篇
  1997年   48篇
  1996年   42篇
  1995年   33篇
  1994年   38篇
  1993年   28篇
  1992年   25篇
  1991年   37篇
  1990年   39篇
  1989年   22篇
  1988年   30篇
  1986年   34篇
  1985年   35篇
  1984年   33篇
  1983年   38篇
  1982年   42篇
  1981年   44篇
  1980年   38篇
  1979年   35篇
  1978年   36篇
  1977年   31篇
  1976年   34篇
  1975年   28篇
  1974年   27篇
  1973年   23篇
排序方式: 共有7813条查询结果,搜索用时 15 毫秒
101.

Background

Guided internet-delivered cognitive behaviour therapy (ICBT) has been found to be effective in the treatment of mild to moderate depression, but there have been no direct comparisons with the more established group-based CBT with a long-term follow-up.

Method

Participants with mild to moderate depression were recruited from the general population and randomized to either guided ICBT (n=33) or to live group treatment (n=36). Measures were completed before and after the intervention to assess depression, anxiety, and quality of life. Follow-ups were conducted at one-year and three-year after the treatment had ended.

Results

Data were analysed on an intention-to-treat basis using linear mixed-effects regression analysis. Results on the self-rated version of the Montgomery–Åsberg Depression Scale showed significant improvements in both groups across time indicating non-inferiority of guided ICBT, and there was even a tendency for the guided ICBT group to be superior to group-based CBT at three year follow-up. Within-group effect sizes for the ICBT condition at post-treatment showed a Cohen′s d=1.46, with a similar large effect at 3-year follow-up, d=1.78. For the group CBT the corresponding within-group effects were d=0.99 and d=1.34, respectively.

Limitations

The study was small with two active treatments and there was no placebo or credible control condition.

Conclusions

Guided ICBT is at least as effective as group-based CBT and long-term effects can be sustained up to 3 years after treatment.  相似文献   
102.
103.
104.
Protein aggregation and ordered fibrillar amyloid deposition inside and outside of the central nervous system cells is the common pathologic hallmark of most aging-related neurodegenerative disorders. Dominant mutations in the gene encoding superoxide dismutase 1 (SOD1) protein are linked to familial amyotrophic lateral sclerosis (ALS), a neurodegenerative disease characterized by progressive degeneration of motor neurons, leading to muscle paralysis and death. The major histochemical hallmark in the remaining motor neurons of ALS is the intracellular accumulation of ubiquitinated inclusions consisting of insoluble aberrant protein aggregates. However, the molecular pathomechanisms underlying the process have been elusive. Here for the first time, we report that E6-AP, a homologous to E6-AP C terminus-type E3 ubiquitin ligase depleted in ALS mouse models before neurodegeneration. E6-AP coimmunoprecipitates with the SOD1 protein and is predominantly mislocalized in mutant SOD1-containing inclusion bodies. Overexpression of E6-AP increases the ubiquitination and facilitates degradation of SOD1 proteins. Finally, we show that the overexpression of E6-AP suppresses the aggregation and cell death mediated by mutated SOD1 proteins and cellular protective effect is more prominent when E6-AP is overexpressed along with Hsp70. These data suggest that enhancing the activity of E6-AP ubiquitin ligase might be a viable therapeutic strategy to eliminate mutant SOD1-mediated toxicity in ALS.  相似文献   
105.
Inhibitory interneurons expressing parvalbumin (PV) are central to cortical network dynamics, generation of γ oscillations, and cognition. Dysfunction of PV interneurons disrupts cortical information processing and cognitive behavior. Brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase B (trkB) signaling regulates the maturation of cortical PV interneurons but is also implicated in their adult multidimensional functions. Using a novel viral strategy for cell-type-specific and spatially restricted expression of a dominant-negative trkB (trkB.DN), we show that BDNF/trkB signaling is essential to the integrity and maintenance of prefrontal PV interneurons in adult male and female mice. Reduced BDNF/trkB signaling in PV interneurons in the medial prefrontal cortex (mPFC) resulted in deficient PV inhibition and increased baseline local field potential (LFP) activity in a broad frequency band. The altered network activity was particularly pronounced during increased activation of the prefrontal network and was associated with changed dynamics of local excitatory neurons, as well as decreased modulation of the LFP, abnormalities that appeared to generalize across stimuli and brain states. In addition, our findings link reduced BDNF/trkB signaling in prefrontal PV interneurons to increased aggression. Together our investigations demonstrate that BDNF/trkB signaling in PV interneurons in the adult mPFC is essential to local network dynamics and cognitive behavior. Our data provide direct support for the suggested association between decreased trkB signaling, deficient PV inhibition, and altered prefrontal circuitry.SIGNIFICANCE STATEMENT Brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase B (trkB) signaling promotes the maturation of inhibitory parvalbumin (PV) interneurons, neurons central to local cortical dynamics, γ rhythms, and cognition. Here, we used a novel viral approach for reduced BDNF/trkB signaling in PV interneurons in the medial prefrontal cortex (mPFC) to establish the role of BDNF/trkB signaling in adult prefrontal network activities. Reduced BDNF/trkB signaling caused pronounced morphologic alterations, reduced PV inhibition, and deficient prefrontal network dynamics. The altered network activity appeared to manifest across stimuli and brain states and was associated with aberrant local field potential (LFP) activities and increased aggression. The results demonstrate that adult BDNF/trkB signaling is essential to PV inhibition and prefrontal circuit function and directly links BDNF/trkB signaling to network integrity in the adult brain.  相似文献   
106.
Small, non-enveloped RNA viruses belonging to the genera Sapovirus, Kobuvirus, and Mamastrovirus are usually associated with gastroenteritis in humans and animals. These enteric pathogens are considered potential zoonotic agents. In this study, the prevalence and genetic diversity of sapoviruses (SaVs), kobuviruses (KoVs), and astroviruses (AstVs) in asymptomatic pigs were investigated using a PCR approach. KoV was found to be the most prevalent virus (87.3 %), followed by AstV (34.2 %) and SaV (10.2 %). Interestingly, the intra- and inter-cluster distances between porcine SaV capsid sequences revealed one strain (P38/11/CZ) that formed a new genotype within genogroup III of porcine SaVs, and it is tentatively called “P38/11-like” genotype. Moreover, this is the first report of porcine kobuvirus detection on Czech pig farms. The high prevalence rate of gastroenteritis-producing viruses in clinically healthy pigs represents a continuous source of infection of pigs, and possibly to humans.  相似文献   
107.
108.
Chelicerata, the second largest subphylum of Arthropoda, includes invertebrates with a wide range of body size. Pseudoscorpions are among small or miniature chelicerates which exhibit several morphological, anatomical, and developmental features related to miniaturization, e.g., replacement of book lungs by tracheae, unpaired gonads, and matrotrophic development of the embryos outside the female body, in the brood sac. In this paper, we show the ovary structure of two pseudoscorpion species, Cheiridium museorum and Apocheiridium ferum (Cheiridiidae). Both cheiridiids are one of the smallest pseudoscorpions. The results of our observations conducted in light, transmission electron, and confocal microscopy demonstrate that the ovary of C. museorum and A. ferum, displays a significant structural difference that is unusual for chelicerates. The difference concerns the spatially restricted position of the germarium. We show that such ovary architecture results in a significantly reduced number of growing oocytes and in consequence a reduced number of deposited eggs. A centrally located germarium implies also a modified pattern of ovary development during oocyte growth due to long distance migration of the germline and the accompanying somatic cells. Herein, we postulate that such an ovary structure is related to the pseudoscorpion's small body size and it is a step towards miniaturization in the smaller pseudoscorpions species.  相似文献   
109.
Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases leading to pruritic skin lesions. A subset of AD patients exhibits a disseminated severe HSV infection called eczema herpeticum (EH) that can cause life-threatening complications. This review gives an overview of the clinical picture, and characteristics of the patients as well as the diagnosis and therapy of EH. A special focus lies on the pathophysiological hallmarks identified so far that predispose for EH. This aspect covers genetic aberrations, immunological changes, and environmental influences displaying a complex multifactorial situation, which is not completely understood. Type 2 skewing of virus-specific T cells in ADEH+ patients has been implicated in immune profile abnormalities, along with impaired functions of dendritic cells and natural killer cells. Furthermore, aberrations in interferon pathway-related genes such as IFNG and IFNGR1 have been identified to increase the risk of EH. IL-4, IL-25, and thymic stromal lymphopoietin (TSLP) are overexpressed in EH, whereas antimicrobial peptides like human β-defensins and LL-37 are reduced. Concerning the epidermal barrier, single nucleotide polymorphisms (SNPs) in skin barrier proteins such as filaggrin were identified in ADEH+ patients. A dysbalance of the skin microbiome also contributes to EH due to an increase of Staphylococcus aureus, which provides a supporting role to the viral infection via secreted toxins such as α-toxin. The risk of EH is reduced in AD patients treated with dupilumab. Further research is needed to identify and specifically target risk factors for EH in AD patients.  相似文献   
110.
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