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   22659篇
  免费   1716篇
  国内免费   32篇
耳鼻咽喉   172篇
儿科学   754篇
妇产科学   615篇
基础医学   2971篇
口腔科学   239篇
临床医学   2920篇
内科学   4198篇
皮肤病学   278篇
神经病学   2231篇
特种医学   436篇
外科学   2256篇
综合类   379篇
一般理论   81篇
预防医学   3421篇
眼科学   242篇
药学   1298篇
中国医学   17篇
肿瘤学   1899篇
  2024年   41篇
  2023年   299篇
  2022年   467篇
  2021年   969篇
  2020年   606篇
  2019年   926篇
  2018年   932篇
  2017年   696篇
  2016年   743篇
  2015年   766篇
  2014年   991篇
  2013年   1358篇
  2012年   2081篇
  2011年   2009篇
  2010年   1053篇
  2009年   848篇
  2008年   1491篇
  2007年   1407篇
  2006年   1399篇
  2005年   1272篇
  2004年   1099篇
  2003年   906篇
  2002年   795篇
  2001年   105篇
  2000年   99篇
  1999年   120篇
  1998年   172篇
  1997年   98篇
  1996年   72篇
  1995年   60篇
  1994年   41篇
  1993年   49篇
  1992年   30篇
  1991年   25篇
  1990年   30篇
  1989年   18篇
  1988年   18篇
  1987年   17篇
  1986年   17篇
  1985年   28篇
  1984年   29篇
  1983年   24篇
  1982年   30篇
  1981年   38篇
  1980年   17篇
  1979年   10篇
  1978年   14篇
  1977年   10篇
  1975年   9篇
  1973年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
The bone marrow is the site of neutrophil production, a process that is regulated by the cytokine granulocyte colony‐stimulating factor (G‐CSF). Mature neutrophils are continually released into the circulation, with an estimated 10 11 neutrophils exiting the bone marrow daily under basal conditions. These leucocytes have a short half‐life in the blood of ~6·5 hr, and are subsequently destroyed in the spleen, liver and indeed the bone marrow itself. Additionally, mature neutrophils are retained in the bone marrow by the stromal cell‐derived factor (SDF‐1α)/chemokine (C‐X‐C motif) receptor 4 (CXCR4) chemokine axis and form the bone marrow reserve. Following infection or inflammatory insult, neutrophil release from the bone marrow reserve is substantially elevated and this process is mediated by the co‐ordinated actions of cytokines and chemokines. In this review we discuss the factors and molecular mechanisms regulating the neutrophil mobilization and consider the mechanisms and functional significance of neutrophil clearance via the bone marrow.  相似文献   
33.
The Valsalva maneuver, a test frequently used to evaluate autonomic function, recruits discrete neural sites. The time courses of neural recruitment relative to accompanying cardiovascular and breathing patterns are unknown. We examined functional magnetic resonance imaging signal changes within the brain to repeated Valsalva maneuvers and correlated these changes with physiological trends. In 12 healthy subjects (age, 30-58 yr), a series of 25 volumes (20 gradient echo echo-planar image slices per volume) was collected using a 1.5-Tesla scanner during a 60-s baseline and 90-s challenge period consisting of three Valsalva maneuvers. Regions of interest were examined for signal intensity changes over baseline and challenge conditions in cardiorespiratory-related regions. In addition, whole brain correlations between signal intensity and heart rate and airway load pressure were performed on a voxel-by-voxel basis. Significant signal changes, correlated with the time course of load pressure and heart rate, emerged within multiple areas, including the amygdala and hippocampus, insular and lateral frontal cortices, dorsal pons, dorsal medulla, lentiform nucleus, and fastigial and dentate nuclei of the cerebellum. Signal intensities peaked early in the Valsalva maneuver within the hippocampus and amygdala, later within the dorsal medulla, pons and midbrain, and deep cerebellar nuclei, and last within the lentiform nuclei and the lateral prefrontal cortex. The ventral pontine signals increased during the challenge, but not in a fashion correlated to load pressure or heart rate. Sites showing little or no correlation included the vermis and medial prefrontal cortex. These data suggest an initiating component arising in rostral brain areas, a later contribution from cerebellar nuclei, basal ganglia, and lateral prefrontal cortex, and a role for the ventral pons in mediating longer term processes.  相似文献   
34.
Quality of Life Research - Quality of life can be negatively impacted by the formation of a stoma and is influenced by a number of factors. Research to date treats people with a stoma as a...  相似文献   
35.
Maternal and Child Health Journal - This study assessed whether the use of a peer-to-peer educational book, written and illustrated by women who experienced common mental disorders (CMDs) in the...  相似文献   
36.
Maternal and Child Health Journal - Understand whether and how Black adolescent daughters’ relationships with their single mothers could be strengthened through an intervention to address...  相似文献   
37.
Maternal and Child Health Journal - Perinatal mood and anxiety disorders can have far reaching negative impact on both maternal mental health and child growth and development. Multimodal group...  相似文献   
38.
IntroductionDetermining the efficacy of anti-scar technologies can be difficult as qualitative, subjective assessments are often utilized instead of systematic, objective measures. Perceptions regarding the reliability of instruments for quantitative measurements along with their high cost and increased data collection time may discourage their use, leading to use of scar scales which are relatively quick and low-cost. To directly evaluate the reliability of instruments for quantitative measurements of scar properties, instruments and two qualitative scales were compared by assessing a variety of cutaneous scars.MethodsScar height and surface texture were evaluated using a 3D scanner and a mold/cast technique. Scar color was evaluated by using a spectroscopy-based tool, the Mexameter®, and digital photography with image analysis. Scar biomechanics were evaluated using the BTC-2000?, Dermal Torque Meter (DTM®), and ballistometer®. The Vancouver Scar Scale (VSS) and Patient and Observer Scar Assessment Scale (POSAS) were used to qualitatively evaluate the same scar properties. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-user reliability (poor, moderate, good, excellent) with all instruments and the kappa reliability statistic was used to asses inter-user reliability (poor, fair, moderate, good, very good) for VSS and POSAS. Time for measurement collection and after collection analysis was also recorded.ResultsThe Mexameter® was the most reliable method for evaluating erythema and pigmentation compared to digital photography and image processing, POSAS and VSS. Digital photography and analysis was more reliable than POSAS and VSS. Assessment of scar height was significantly more reliable when using a 3D scanner versus VSS and POSAS. The 3D scanner and mold-cast techniques also offered an additional benefit of providing an absolute value of scar height relative to the surrounding tissue. Intra-user reliability for all mechanical tests was moderate to good. Inter-user reliability was greater when using the BTC-2000? and ballistometer® versus the DTM®. All quantitative measurements took less than 90 s for collection, with the exception of the mold/cast technique.ConclusionNon-invasive instruments allow scar properties to be quantitatively assessed with high sensitivity and as a function of time and/or treatment without the need for biopsy collection. Overall, the reliability of scar assessments was significantly improved when quantitative instruments were utilized versus scar scales. Quantitative assessment of color and biomechanics were swift, requiring less than 90 s per measurement while assessments of texture and height required additional analysis time after collection. With proper training of clinical staff and well-defined protocols for measurement collection, reliable, quantitative assessments of scar properties can be collected with little disruption to the clinical workflow.  相似文献   
39.
Diabetic foot ulcers (DFUs) are a common but highly morbid complication of long-standing diabetes, carrying high rates of associated major amputation and mortality. As the global incidence of diabetes has increased, along with the lifespan of the diabetic patient, the worldwide burden of DFUs has grown steadily. Outcomes in diabetes and DFUs are known to depend strongly on social determinants of health, with worse outcomes noted in minority and socioeconomically disadvantaged populations. Effective treatment of DFUs is complex, requiring considerable expenditure of resources and significant cost to the health care system. Comprehensive care models with multidisciplinary teams have proven effective in the treatment of DFUs by decreasing barriers to care and increasing access to the multiple specialists required to provide timely and effective DFU procedural intervention, surveillance, and preventative care. Vascular surgeons are an integral part throughout the cycle of care for DFUs and should be involved early in the course of such patients to maximize their contributions to a multidisciplinary care model.  相似文献   
40.
We present a case of a neonate with trisomy 21, ductal-dependent aortic coarctation, and severe respiratory failure secondary to coronavirus disease 2019 (COVID-19) pneumonia. The neonate was managed with venoarterial extracorporeal membrane oxygenation (VA ECMO), palliative stenting of the coarctation, and a vascular plug occlusion of a large patent ductus arteriosus. The patient was successfully weaned off extracorporeal membrane oxygenation (ECMO). The patient is currently awaiting a definitive surgical repair in the near future.  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