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   1256篇
  免费   76篇
  国内免费   5篇
耳鼻咽喉   5篇
儿科学   30篇
妇产科学   15篇
基础医学   202篇
口腔科学   20篇
临床医学   144篇
内科学   265篇
皮肤病学   28篇
神经病学   180篇
特种医学   33篇
外科学   114篇
综合类   11篇
一般理论   3篇
预防医学   72篇
眼科学   41篇
药学   104篇
肿瘤学   70篇
  2024年   2篇
  2023年   12篇
  2022年   24篇
  2021年   48篇
  2020年   28篇
  2019年   40篇
  2018年   44篇
  2017年   35篇
  2016年   40篇
  2015年   42篇
  2014年   60篇
  2013年   70篇
  2012年   92篇
  2011年   91篇
  2010年   81篇
  2009年   59篇
  2008年   95篇
  2007年   72篇
  2006年   72篇
  2005年   60篇
  2004年   50篇
  2003年   45篇
  2002年   42篇
  2001年   7篇
  2000年   11篇
  1999年   10篇
  1998年   10篇
  1997年   3篇
  1996年   8篇
  1995年   2篇
  1994年   2篇
  1993年   5篇
  1992年   6篇
  1991年   3篇
  1988年   5篇
  1987年   4篇
  1986年   3篇
  1985年   4篇
  1983年   2篇
  1978年   2篇
  1977年   2篇
  1976年   3篇
  1975年   4篇
  1974年   5篇
  1973年   3篇
  1972年   8篇
  1970年   2篇
  1968年   2篇
  1967年   4篇
  1966年   2篇
排序方式: 共有1337条查询结果,搜索用时 15 毫秒
61.
Studies have shown that the predictive value of “clinical diagnoses” of influenza and other respiratory viral infections is low, especially in children. In routine care, pediatricians often resort to clinical diagnoses, even in the absence of robust evidence‐based criteria. We used a dual approach to identify clinical characteristics that may help to differentiate infections with common pathogens including influenza, respiratory syncytial virus, adenovirus, metapneumovirus, rhinovirus, bocavirus‐1, coronaviruses, or parainfluenza virus: (a) systematic review and meta‐analysis of 47 clinical studies published in Medline (June 1996 to March 2017, PROSPERO registration number: CRD42017059557) comprising 49 858 individuals and (b) data‐driven analysis of an inception cohort of 6073 children with ILI (aged 0‐18 years, 56% male, December 2009 to March 2015) examined at the point of care in addition to blinded PCR testing. We determined pooled odds ratios for the literature analysis and compared these to odds ratios based on the clinical cohort dataset. This combined analysis suggested significant associations between influenza and fever or headache, as well as between respiratory syncytial virus infection and cough, dyspnea, and wheezing. Similarly, literature and cohort data agreed on significant associations between HMPV infection and cough, as well as adenovirus infection and fever. Importantly, none of the abovementioned features were unique to any particular pathogen but were also observed in association with other respiratory viruses. In summary, our “real‐world” dataset confirmed published literature trends, but no individual feature allows any particular type of viral infection to be ruled in or ruled out. For the time being, laboratory confirmation remains essential. More research is needed to develop scientifically validated decision models to inform best practice guidelines and targeted diagnostic algorithms.  相似文献   
62.
2B4 (CD244), a member of the SLAM‐related receptor family, has important immuno‐regulatory functions including coactivating the cytotoxicity and cytokine secretion of NK cells. Immune modulation by 2B4 is dependent on the small intracellular signaling molecule SAP. In patients suffering from X‐linked lymphoproliferative disease (XLP1), SAP is nonfunctional, not only abolishing the activating function of 2B4, but rendering this receptor inhibitory. In this issue of European Journal of Immunology, Meazza et al. [Eur. J. Immunol. 2014. 44: 1526–1534.] demonstrate that 2B4‐mediated inhibition in NK cells from XLP1 patients is selective. While the activation of NK cells via ITAM‐based receptors is blocked by inhibitory 2B4, DNAM‐1, and NKG2D‐dependent NK‐cell activation is not affected by SAP deficiency. These findings provide an important insight into the different defective NK‐cell functions in XLP1 patients and demonstrate the differential integration of redundant receptor signaling pathways in NK cells.  相似文献   
63.
PURPOSE: We examined the performance of a familial risk assessment method that stratifies risk for early-onset coronary heart disease by considering the number of relatives with coronary disease, degree of relationship, lineage, and age at diagnosis. METHODS: By using data from the HealthStyles 2003 survey, we assessed the associations between familial risk and early-onset coronary heart disease, diabetes, hypercholesterolemia, hypertension, and obesity. By using area under the curve statistics, we evaluated the discriminatory ability of various risk assessment models. RESULTS: Of 4,035 respondents, 60% were female and 72% were white, with a mean age of 48.8 years. After adjustment for demographics, strong and moderate risk were significantly associated with approximately a five- and twofold risk of early-onset coronary disease, respectively. After adjustment for demographics and personal history of cardiovascular disease, strong familial risk was also significantly associated with diabetes, hypercholesterolemia, hypertension, and obesity. A risk assessment model that included familial risk, demographics, and personal history of diabetes, hypercholesterolemia, hypertension, and obesity was most optimal with an area under the curve statistic of 87.2% CONCLUSIONS: Familial risk assessment can stratify risk for early-onset coronary heart disease. Several conditions associated with increased familial risk can be prevented. These results have important implications for risk assessment and risk-reducing interventions.  相似文献   
64.
65.
The practice of weaning premature infants from continuous positive airway pressure (CPAP) varies considerably and is usually performed without written standards. In this study, the feasibility of a standardized weaning approach was evaluated. In a quasi-experimental design, data from a prospective, post-intervention cohort (n=41) were compared to data from a pre-intervention cohort (n=36). Standardized weaning was feasible but no significant differences in short-term respiratory outcomes were observed. Weaning from CPAP was achieved at 32.1?±?1.6 (post-intervention) versus 32.5?±?2.3 weeks (pre-intervention) postmenstrual age. More rigorous, large-scale clinical trials are necessary before firm recommendations on distinct weaning regimens can be made.  相似文献   
66.
67.
During Alzheimer’s disease (AD) progression, microglial cells play complex roles and have potentially detrimental as well as beneficial effects. The use of appropriate model systems is essential for characterizing and understanding the roles of microglia in AD pathology. Here, we used organotypic hippocampal slice cultures (OHSCs) to investigate the impact of microglia on amyloid beta (Aβ)‐mediated toxicity. Neurons in OHSCs containing microglia were not vulnerable to cell death after 7 days of repeated treatment with Aβ1‐42 oligomer‐enriched preparations. However, when clodronate was used to remove microglia, treatment with Aβ1‐42 resulted in significant neuronal death. Further investigations indicated signs of endoplasmic reticulum stress and caspase activation after Aβ1‐42 challenge only when microglia were absent. Interestingly, microglia provided protection without displaying any classic signs of activation, such as an amoeboid morphology or the release of pro‐inflammatory mediators (e.g., IL‐6, TNF‐α, NO). Furthermore, depleting microglia or inhibiting microglial uptake mechanisms resulted in significant more Aβ deposition compared to that observed in OHSCs containing functional microglia, suggesting that microglia efficiently cleared Aβ. Because inhibiting microglial uptake increased neuronal cell death, the ability of microglia to engulf Aβ is thought to contribute to its protective properties. Our study argues for a beneficial role of functional ramified microglia whereby they act against the accumulation of neurotoxic forms of Aβ and support neuronal resilience in an in situ model of AD pathology.  相似文献   
68.

Objective

To examine how type and severity of patients’ negative emotions influence oncologists’ responses and subsequent conversations.

Methods

We analyzed 264 audio-recorded conversations between advanced cancer patients and their oncologists. Conversations were coded for patients’ expressions of negative emotion, which were categorized by type of emotion and severity. Oncologists’ responses were coded as using either empathic language or blocking and distancing approaches.

Results

Patients presented fear more often than anger or sadness; severity of disclosures was most often moderate. Oncologists responded to 35% of these negative emotional disclosures with empathic language. They were most empathic when patients presented intense emotions. Responding empathically to patients’ emotional disclosures lengthened discussions by an average of only 21 s.

Conclusion

Greater response rates to severe emotions suggest oncologists may recognize negative emotions better when patients express them more intensely. Oncologists were least responsive to patient fear and responded with greatest empathy to sadness.

Practice implications

Oncologists may benefit from additional training to recognize negative emotions, even when displayed without intensity. Teaching cancer patients to better articulate their emotional concerns may also enhance patient–oncologist communication.  相似文献   
69.
Adolescence is a transition period that is assumed to be characterized by increased sensitivity to reward. While there is growing research on reward processing in adolescents, investigations into the engagement of brain regions under different reward-related conditions in one sample of healthy adolescents, especially in a target age group, are missing. We aimed to identify brain regions preferentially activated in a reaction time task (monetary incentive delay (MID) task) and a simple guessing task (SGT) in a sample of 14-year-old adolescents (N?=?54) using two commonly used reward paradigms. Functional magnetic resonance imaging was employed during the MID with big versus small versus no win conditions and the SGT with big versus small win and big versus small loss conditions. Analyses focused on changes in blood oxygen level?Cdependent contrasts during reward and punishment processing in anticipation and feedback phases. We found clear magnitude-sensitive response in reward-related brain regions such as the ventral striatum during anticipation in the MID task, but not in the SGT. This was also true for reaction times. The feedback phase showed clear reward-related, but magnitude-independent, response patterns, for example in the anterior cingulate cortex, in both tasks. Our findings highlight neural and behavioral response patterns engaged in two different reward paradigms in one sample of 14-year-old healthy adolescents and might be important for reference in future studies investigating reward and punishment processing in a target age group.  相似文献   
70.
Lynch syndrome is the most common cause of inherited colorectal cancer, accounting for approximately 3% of all colorectal cancer cases in the United States. In 2009, an evidence-based review process conducted by the independent Evaluation of Genomic Applications in Practice and Prevention Working Group resulted in a recommendation to offer genetic testing for Lynch syndrome to all individuals with newly diagnosed colorectal cancer, with the intent of reducing morbidity and mortality in family members. To explore issues surrounding implementation of this recommendation, the Centers for Disease Control and Prevention convened a multidisciplinary working group meeting in September 2010. This article reviews background information regarding screening for Lynch syndrome and summarizes existing clinical paradigms, potential implementation strategies, and conclusions which emerged from the meeting. It was recognized that widespread implementation will present substantial challenges, and additional data from pilot studies will be needed. However, evidence of feasibility and population health benefits and the advantages of considering a public health approach were acknowledged. Lynch syndrome can potentially serve as a model to facilitate the development and implementation of population-level programs for evidence-based genomic medicine applications involving follow-up testing of at-risk relatives. Such endeavors will require multilevel and multidisciplinary approaches building on collaborative public health and clinical partnerships.  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