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   2432篇
  免费   173篇
  国内免费   17篇
耳鼻咽喉   12篇
儿科学   63篇
妇产科学   63篇
基础医学   410篇
口腔科学   17篇
临床医学   253篇
内科学   516篇
皮肤病学   35篇
神经病学   259篇
特种医学   49篇
外科学   288篇
综合类   21篇
一般理论   3篇
预防医学   204篇
眼科学   70篇
药学   182篇
中国医学   12篇
肿瘤学   165篇
  2023年   9篇
  2022年   41篇
  2021年   56篇
  2020年   35篇
  2019年   68篇
  2018年   63篇
  2017年   44篇
  2016年   44篇
  2015年   46篇
  2014年   74篇
  2013年   116篇
  2012年   170篇
  2011年   169篇
  2010年   90篇
  2009年   91篇
  2008年   157篇
  2007年   187篇
  2006年   165篇
  2005年   157篇
  2004年   162篇
  2003年   133篇
  2002年   155篇
  2001年   18篇
  2000年   17篇
  1999年   15篇
  1998年   23篇
  1997年   21篇
  1996年   13篇
  1995年   16篇
  1994年   9篇
  1993年   11篇
  1992年   7篇
  1991年   8篇
  1990年   7篇
  1989年   6篇
  1988年   12篇
  1987年   14篇
  1985年   13篇
  1984年   7篇
  1982年   7篇
  1981年   18篇
  1980年   11篇
  1979年   9篇
  1978年   10篇
  1976年   6篇
  1974年   7篇
  1973年   9篇
  1972年   6篇
  1958年   6篇
  1954年   5篇
排序方式: 共有2622条查询结果,搜索用时 0 毫秒
81.
We examined the association between household food insecurity and early child development and whether or not maternal depression and anxiety modifies this association. The cross‐sectional study included 468 mother–infant pairs recruited at primary health centers of the Federal District, Brazil. Mothers answered a questionnaire that evaluated early child development (outcome), household food insecurity (independent variable), maternal depression and trait anxiety (effect modifiers). Variables were collected with validated questionnaires for the Brazilian population. Pearson's χ2 test and logistic regression analyses were conducted. Infants who lived in a moderate or severe food insecure household had 2.52 times (95% confidence interval [CI] [1.13, 5.65]) the odds of having early child development delays compared with infants in secure households. Maternal depression and anxiety modified the strength of association between household food insecurity and early child development, which is an innovative finding. Among infants with depressed mothers, those experiencing mild (adjusted odds ratio [aOR] 3.33, 95% CI [1.17, 9.46]) and moderate/severe household food insecurity (aOR 10.13, 95% CI [2.18, 47.10]) had higher odds of having early child development delays, compared with infants in food secure households. Among infants with both anxious and depressed mothers, these associations were even stronger for mild (aOR 4.69, 95% CI [1.41, 15.59]) and moderate/severe household food insecurity (aOR 16.07, 95% CI [2.70, 95.66]). In conclusion, household food insecurity is a risk factor for early child development delays, and this association is modified by maternal depression and anxiety. Future studies should evaluate the impact of intervention packages that address maternal depression and anxiety and household food insecurity on preventing early child development delays.  相似文献   
82.
Mild-traumatic brain injury (mTBI) represents ~80% of all emergency room visits and increases the probability of developing long-term cognitive disorders in children. To date, molecular and cellular mechanisms underlying post-mTBI cognitive dysfunction are unknown. Astrogliosis has been shown to significantly alter astrocytes' properties following brain injury, potentially leading to significant brain dysfunction. However, such alterations have never been investigated in the context of juvenile mTBI (jmTBI). A closed-head injury model was used to study jmTBI on postnatal-day 17 mice. Astrogliosis was evaluated using glial fibrillary acidic protein (GFAP), vimentin, and nestin immunolabeling in somatosensory cortex (SSC), dentate gyrus (DG), amygdala (AMY), and infralimbic area (ILA) of prefrontal cortex in both hemispheres from 1 to 30 days postinjury (dpi). In vivo T2-weighted-imaging (T2WI) and diffusion tensor imaging (DTI) were performed at 7 and 30 dpi to examine tissue level structural alterations. Increased GFAP-labeling was observed up to 30 dpi in the ipsilateral SSC, the initial site of the impact. However, vimentin and nestin expression was not perturbed by jmTBI. The morphology of GFAP positive cells was significantly altered in the SSC, DG, AMY, and ILA up to 7 dpi that some correlated with magnetic resonance imaging changes. T2WI and DTI values were significantly altered at 30 dpi within these brain regions most prominently in regions distant from the impact site. Our data show that jmTBI triggers changes in astrocytic phenotype with a distinct spatiotemporal pattern. We speculate that the presence and time course of astrogliosis may contribute to pathophysiological processes and long-term structural alterations following jmTBI.  相似文献   
83.
Objective: This study analyzed the health-seeking behavior of Filipinos using Google Trends tool to quantify relative search volume by term . Oral cancer, mouth cancer, tongue cancer, gum cancer, and lip cancer were used as predetermined search terms. Material and method: Comma-separated values file containing relative search volumes of search trends pertaining to oral cancer from 2009 to 2019 were assessed. Brown-Forsythe one-way ANOVA was used to measure differences with respect to oral cancer across different years and months. Two-way repeated measures ANOVA was applied to detect differences regarding mouth cancer, tongue cancer, gum cancer, and lip cancer across the years. Time series models were fitted and used to forecast search interests. Results: The results revealed that interest in oral cancer was significantly higher in 2019 (43.75±5.5, p <0.05) compared to 2009 (29.0 ± 6.7). In terms of months, searches were higher in February (45.0 ± 6.6) compared to May (24.8 ± 3.4, p=0.015), June (25.3 ± 4.4, p=0.020), and December (26.5 ± 4.0, p=0.038). Search interests for gum cancer and lip cancer remained significantly lower from 2011 to 2019, and tongue cancer from 2016 to 2018 but approximated mouth cancer in 2019. The forecast showed that mouth cancer (31.67%), tongue cancer (23.75%), and lip cancer (3.83%) would fluctuate through time pass, while gum cancer (8%) would remain steady in 2020. Conclusion: Health-seeking behavior through search trends showed an increased interest in oral cancer in 2019 and during February. It was anticipated that search interests would fluctuate in 2020, but at the end of the year would decrease for mouth cancer and tongue cancer, increase for lip cancer, and remain steady for gum cancer.  相似文献   
84.
In recent years, the advancement of technology brought the laser powder bed fusion process to its industrialisation step. Despite all the advancements in process repeatability and general quality control, many challenges remain unsolved due to the intrinsic difficulties of the process, notably the residual stresses issue. This work aimed to assess the usability of Barkhausen noise analysis (BNA) for the residual stress in situ monitoring of laser powder bed fusion on Maraging steel 300 (18Ni-300/1.2709). After measuring the evolution of grain size distribution over process parameter changes, two series of experiments were designed. First, a setup with an external force allows to validate the working principle of BNA on the chosen material processed using LPBF. The second experiment uses on-plates samples with different residual stress states. The results show a good stability in microstructure, a prerequisite for BNA. In addition, the external load setup acknowledges that signal variation correlates with the induced stress state. Finally, the on-plate measurement shows a similar signal variation to what has been observed in the literature for residual stress variation. It is shown that BNA is a suitable method for qualitative residual stresses variation monitoring developed during the LPBF process and underlines that BNA is a promising candidate as an in situ measurement method.  相似文献   
85.
86.
87.
Acute graft-versus-host disease (aGVHD) is a severe complication of allogeneic hematopoietic stem cell transplantation. The role of Th17 cells in its pathophysiology remains a matter of debate. In this study, we assessed whether enrichment of human peripheral blood mononuclear cells (PBMCs) with in vitro Th17-polarized CD4+ T cells would exacerbate xenogeneic GVHD (xGVHD) into NOD-scid IL-2Rγ null (NSG) mice. Naive human CD4+ T cells were stimulated under Th17-skewing conditions for 8 to 10 days and then coinjected in NSG mice with fresh PBMCs from the same donor. We observed that Th17-polarized cells engrafted and migrated toward xGVHD target organs. They also acquired a double-expressing IL-17A+IFNγ+ profile in vivo. Importantly, cotransfer of Th17-polarized cells (1?×?106) with PBMCs (1?×?106) exacerbated xGVHD compared with transplantation of PBMCs alone (2?×?106). Furthermore, PBMC cotransfer with Th17-polarized cells was more potent for xGVHD induction than cotransfer with naive CD4+ T cells stimulated in nonpolarizing conditions (Th0 cells, 1?×?106?+?1?×?106 PBMCs) or with Th1-polarized cells (1?×?106?+?1?×?106 PBMCs). In summary, our results suggest that human Th17-polarized cells can cooperate with PBMCs and be pathogenic in the NSG xGVHD model.  相似文献   
88.
Objectives: To evaluate the effect of high‐dose chemotherapy (HDT) followed by autologous stem cell transplantation (ASCT) on bone turnover and bone mineral density in a cohort of 39 consecutive patients with multiple myeloma (MM). Methods: Phosphorus and calcium parameters, bone turnover markers, and bone mineral density were studied. Timepoints were diagnosis (T1), just before ASCT (T2), 6 months (T3) after ASCT, and 1 yr (T4) after ASCT. Results: No bone mineral loss was shown on dual‐energy X‐ray absorptiometry (DXA) at T1 (lumbar Z‐score ?0.02, femoral neck Z‐score 0.77) or during follow‐up. Chronic vitamin D deficiency (25OHD3 11.7 ± 7.7 ng/mL at T1) and relative hyperparathyroidism from T2 to T4 were observed. In spite of this moderate hyperparathyroidism, serum C‐telopeptide of type I collagen (CTX) decreased significantly between T1 and T4. Bone alkaline phosphatase levels were low at diagnosis and showed no significant change after ASCT, unlike DKK1 levels that were high at diagnosis and decreased 6 months after ASCT in patients not previously treated with bisphosphonates. Conclusion: Bone demineralization is moderate in multiple myeloma. ASCT induces a decrease in bone resorption but no changes in bone formation, remaining low despite the decrease in DKK1. Bone mineral loss, evaluated by DXA, is moderate in multiple myeloma. High‐dose chemotherapy followed by ASCT leads to decreased bone resorption but osteoblastic bone formation remains low, in spite of reduced circulating DKK1.  相似文献   
89.
90.
Adequate use of Information and Communication Technologies (ICTs) in health has been shown to save the patient and caregiver time, improve access to the health system, improve diagnosis and control of disease or treatment. All this results in cost savings, and more importantly, they help improve the quality of service and the lives of patients. The purpose of this study is to analyse the differences in the uses of this ICTs between those physicians that belong to Pain Treatment Units (PU) and other physicians that work in pain not linked to these PUs. An online survey, generated by Netquest online survey tool, was sent to both groups of professionals and the data collected was statistical analysed through a logistic regression methodology which is the Logit binomial model. Our results show that those physicians that belong to PUs use ICTs more frequently and consider it more relevant to their clinical practice.  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