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   7228篇
  免费   590篇
  国内免费   7篇
耳鼻咽喉   90篇
儿科学   220篇
妇产科学   198篇
基础医学   906篇
口腔科学   120篇
临床医学   821篇
内科学   1511篇
皮肤病学   48篇
神经病学   746篇
特种医学   174篇
外科学   834篇
综合类   156篇
一般理论   11篇
预防医学   943篇
眼科学   134篇
药学   541篇
中国医学   3篇
肿瘤学   369篇
  2023年   69篇
  2022年   130篇
  2021年   233篇
  2020年   154篇
  2019年   225篇
  2018年   249篇
  2017年   191篇
  2016年   203篇
  2015年   210篇
  2014年   300篇
  2013年   433篇
  2012年   552篇
  2011年   555篇
  2010年   253篇
  2009年   234篇
  2008年   374篇
  2007年   363篇
  2006年   342篇
  2005年   329篇
  2004年   238篇
  2003年   273篇
  2002年   231篇
  2001年   109篇
  2000年   92篇
  1999年   107篇
  1998年   74篇
  1997年   44篇
  1996年   55篇
  1995年   58篇
  1994年   53篇
  1993年   35篇
  1992年   67篇
  1991年   69篇
  1990年   52篇
  1989年   66篇
  1988年   53篇
  1987年   54篇
  1986年   47篇
  1985年   36篇
  1984年   40篇
  1983年   32篇
  1982年   31篇
  1981年   29篇
  1979年   34篇
  1978年   34篇
  1977年   26篇
  1976年   32篇
  1974年   30篇
  1972年   33篇
  1967年   30篇
排序方式: 共有7825条查询结果,搜索用时 10 毫秒
901.
Purpose: the purpose of this study is to identify risk factors for familial, likely genetically-determined, preterm birth.

Materials and methods: We performed a case–control study, enrolling 211 patients (103 cases and 108 controls). Cases delivered between 20 and 35 weeks gestation, with a prior preterm birth or first-degree relative born prematurely. Controls delivered between 37–42 weeks. Groups were compared using a comprehensive questionnaire validated by medical record. Multivariate logistic regression assessed risk factor associations.

Results: Of cases, 30% reported bleeding during pregnancy compared with 5% of controls, adjusted odds ratio (adjOR) 9.0, 95%CI 3.31–24.47. Of cases that delivered at 20–28 weeks, 44.8% reported bleeding during pregnancy compared with 24.6% at 29–35 weeks, p?=?.04. Other associations were prior first-trimester miscarriage adjOR 2.55 (CI 1.21–5.35) or second-trimester miscarriage, adjOR 6.3 (CI 1.76–22.56).

Conclusions: Bleeding during pregnancy and prior miscarriage were significantly associated with familial preterm birth. The magnitude of effect for bleeding in pregnancy was higher with earlier preterm births. These associations warrant further investigation.  相似文献   
902.
A 9-year-old girl developed Reye's syndrome. On admission to the hospital on the fourth day of illness, responses for verbal stimuli had been absent, but were present for painful stimuli. Coma developed on the fourth day and was present until death ten days later. The fundus of both internal meatus showed vascular congestion of nerves with evidence of repeated hemorrhages. All structures within the endolymphatic system showed advanced degeneration, with exception of the tectorial membrane and cupulae. One ear showed vascular congestion, formation of thrombi, and free hemorrhage within the modiolus and spiral ganglion. In the other ear, congested vessels in nerves in the meatus were obstructed by swelling at the cribriform area. The degenerative changes corresponded closely to those produced experimentally in guinea pigs by interruption of arterial circulation to the inner ear.  相似文献   
903.
904.
905.
906.
The global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the disparity between developed and developing countries for infectious disease surveillance and the sequencing of pathogen genomes. The majority of SARS-CoV-2 sequences published are from Europe, North America, and Asia. Between April 2020 and January 2022, 795 SARS-CoV-2-positive nares swabs from individuals in the U.S. Navy installation Camp Lemonnier, Djibouti, were collected, sequenced, and analyzed. In this study, we described the results of genomic sequencing and analysis for 589 samples, the first published viral sequences for Djibouti, including 196 cases of vaccine breakthrough infections. This study contributes to the knowledge base of circulating SARS-CoV-2 lineages in the under-sampled country of Djibouti, where only 716 total genome sequences are available at time of publication. Our analysis resulted in the detection of circulating variants of concern, mutations of interest in lineages in which those mutations are not common, and emerging spike mutations.  相似文献   
907.
BackgroundAs we enter the fifth decade of the AIDS epidemic, health researchers and AIDS activists reflect both on the progress that has been made and the importance of continued prevention efforts for those most at risk. As HIV infection rates continue to fluctuate across communities, a trend has emerged with new HIV infections becoming increasingly concentrated—with cascading effects—among people aged <30 years, from marginalized racial and ethnic groups, and who are sexual or gender minorities.ObjectiveIn this paper, we discuss the renewal of the Healthy Young Men’s (HYM) Cohort Study and the addition of a subcohort—TRUTH: A Transgender Youth of Color Study. The overarching aim of our renewed study was to inform new intervention strategies; understand linkage to care; and examine changes over time with respect to minority-related stress and intersectional identities and their relationship with substance use, mental health, and HIV risk. Findings from this study will help to inform the development of new interventions designed to engage African American and Black and Latino young men who have sex with men (YMSM) and transgender and gender minority youth in the HIV prevention and care continua and to reduce risk by addressing pathways of minority-related stress and intersectional stigma.MethodsLongitudinal study (baseline and follow-up assessments every 6 months for a total of 8 waves of data collection) is ongoing with reconsented cohort from the last iteration of HYM Cohort Study. This study protocol includes self-report survey, collection of urine to assess recent use of illicit drugs, and collection of blood and rectal and throat swabs to test for current sexually transmitted infection and HIV infection. An additional sample of blood and plasma (10 mL for 4 aliquots and 1 pellet) is also collected and stored in the HYM Cohort Study biorepository for future studies. This mixed methods study design includes collection of triangulated analysis of quantitative, qualitative, and biological measures (ie, drug use, sexually transmitted infection and HIV testing, and adherence to antiretroviral therapy among participants who are HIV+) at baseline and every 6 months.ResultsAs of February 2022, participants from the past 4 years of the HYM Cohort Study and TRUTH: A Transgender Youth of Color Study Cohort have been reconsented and enrolled into the renewal period of longitudinal data collection, which is projected from summer of 2020 until summer of 2025. Recruitment is ongoing to reach our target enrollment goal of YMSM and transgender minority youth.ConclusionsThe findings from this study are being used to inform the development of new, and adaptation of existing, evidence-based HIV prevention interventions designed to engage populations of transgender and gender minority youth and YMSM in the HIV prevention and care continua.International Registered Report Identifier (IRRID)DERR1-10.2196/39232  相似文献   
908.
Lesion localization is the basis for understanding neurologic disease, which is predicated on neuroanatomical knowledge carefully cataloged from histology and imaging atlases. However, it is often difficult to correlate clinical images of brainstem injury obtained by MRI scans with the details of human brainstem neuroanatomy represented in atlases, which are mostly based on cytoarchitecture using Nissl stain or a single histochemical stain, and usually do not include the cerebellum. Here, we report a high-resolution (200 μm) 7T MRI of a cadaveric male human brainstem and cerebellum paired with detailed, coregistered histology (at 2 μm single-cell resolution) of the immunohistochemically stained cholinergic, serotonergic, and catecholaminergic (dopaminergic, noradrenergic, and adrenergic) neurons, in relationship to each other and to the cerebellum. These immunohistochemical findings provide novel insights into the spatial relationships of brainstem cell types and nuclei, including subpopulations of melanin and TH+ neurons, and allows for more informed structural annotation of cell groups. Moreover, the coregistered MRI-paired histology helps validate imaging findings. This is useful for interpreting both scans and histology, and to understand the cell types affected by lesions. Our detailed chemoarchitecture and cytoarchitecture with corresponding high-resolution MRI builds on previous atlases of the human brainstem and cerebellum, and makes precise identification of brainstem and cerebellar cell groups involved in clinical lesions accessible for both laboratory scientists and clinicians alike.SIGNIFICANCE STATEMENT Clinicians and neuroscientists frequently use cross-sectional anatomy of the human brainstem from MRI scans for both clinical and laboratory investigations, but they must rely on brain atlases to neuroanatomical structures. Such atlases generally lack both detail of brainstem chemical cell types, and the cerebellum, which provides an important spatial reference. Our current atlas maps the distribution of key brainstem cell types (cholinergic, serotonergic, and catecholaminergic neurons) in relationship to each other and the cerebellum, and pairs this histology with 7T MR images from the identical brain. This atlas allows correlation of the chemoarchitecture with corresponding MRI, and makes the identification of cell groups that are often discussed, but rarely identifiable on MRI scan, accessible to clinicians and clinical researchers.  相似文献   
909.
910.
In this personal view article, I discuss a formative experience I had during an Urban Indigenous Health elective in which I participated while in my final year of medical school. The elective was developed on the foundation of an experiential learning model, which is central to Indigenous pedagogy and emphasizes learning through experience and narrative reflection. By transforming medical education into a place where such concepts are integrated and valued, I argue that we will create physicians who are self-aware, compassionate and able to provide culturally safe care to all patient populations they will serve in their future practices.  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