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   18337篇
  免费   1339篇
  国内免费   46篇
耳鼻咽喉   177篇
儿科学   632篇
妇产科学   500篇
基础医学   2503篇
口腔科学   195篇
临床医学   2202篇
内科学   3427篇
皮肤病学   323篇
神经病学   1932篇
特种医学   492篇
外国民族医学   5篇
外科学   1967篇
综合类   139篇
一般理论   14篇
预防医学   2249篇
眼科学   270篇
药学   1190篇
中国医学   13篇
肿瘤学   1492篇
  2024年   34篇
  2023年   244篇
  2022年   457篇
  2021年   835篇
  2020年   443篇
  2019年   797篇
  2018年   864篇
  2017年   607篇
  2016年   651篇
  2015年   701篇
  2014年   936篇
  2013年   1078篇
  2012年   1673篇
  2011年   1662篇
  2010年   823篇
  2009年   699篇
  2008年   1143篇
  2007年   1127篇
  2006年   1016篇
  2005年   947篇
  2004年   866篇
  2003年   676篇
  2002年   613篇
  2001年   63篇
  2000年   66篇
  1999年   62篇
  1998年   131篇
  1997年   88篇
  1996年   69篇
  1995年   52篇
  1994年   52篇
  1993年   41篇
  1992年   25篇
  1991年   21篇
  1990年   8篇
  1989年   13篇
  1988年   17篇
  1987年   12篇
  1986年   9篇
  1985年   9篇
  1984年   9篇
  1983年   10篇
  1982年   8篇
  1981年   8篇
  1980年   11篇
  1978年   5篇
  1977年   5篇
  1976年   13篇
  1972年   3篇
  1971年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
PurposeThis study examines sociodemographic patterns of exclusive/dual/polytobacco use among U.S. high school students using multiple national surveys.MethodsUsing three national youth surveys (Population Assessment of Tobacco and Health [PATH] Wave 4 [2016–2017], 2017 Youth Risk Behavior Survey, and 2017 National Youth Tobacco Survey), we classified tobacco products into four groups: (1) electronic nicotine delivery systems (ENDS), (2) conventional cigarettes (CCs), (3) other combustible tobacco products, and (4) smokeless tobacco products. We created 16 categories of non/exclusive/dual/polytobacco use within the past 30 days using the four product groups and calculated weighted population prevalence by sex and race/ethnicity (all surveys) and parental education and income (PATH), based on variable availability.ResultsThe results from 9,331, 12,407, and 9,699 high school students in PATH, Youth Risk Behavior Survey, and National Youth Tobacco Survey, respectively, largely agreed and pointed to similar conclusions. ENDS was the most prevalent exclusive use product (3.8%–5.2% across surveys), with CCs falling to second or third (1.2%–2.0% across surveys). By sex, exclusive, dual, and poly smokeless tobacco product use were more common for males, whereas exclusive CC use was more common for females. By race/ethnicity, non-Hispanic Whites had a higher prevalence of exclusive ENDS use and ENDS/CC dual use than non-Hispanic Blacks. As income and parental education levels increased from low to high, the prevalence of exclusive CC use decreased, whereas the prevalence of exclusive ENDS use increased.ConclusionUnderstanding sociodemographic patterns of tobacco use can help identify groups who may be at greater risk for tobacco-related health outcomes.  相似文献   
73.
PurposeTexting is used by many adolescents and has the potential to improve well-being, as youth can reach out for support immediately after experiencing a stressful situation. Many studies have examined whether texting is associated with well-being, but few have used experimental designs, preventing causal claims.MethodsIn this experimental study, 130 adolescents (Mage = 12.41) participated with a same-gender friend whom they texted regularly. Both adolescents completed a task that elicited stress and then engaged in one of the following randomly assigned activities: texting their friend, watching a video on a cellphone (passive-phone condition), or sitting quietly (no activity condition). Participants reported their mood and stress levels after the stress task and again after the activity. Heart rate variability was measured throughout.ResultsParticipants who texted their friend reported higher moods (b = ?.80, standard error [SE] = .24, p < .001, ηp2 = .09) and lower stress at the end of the study than those in the no activity condition (b = .51, SE = .25, p = .046, ηp2 = .04) and higher moods than adolescents in the passive-phone condition (b = ?.74, SE = .25, p = .004, ηp2 = .08). No differences were noted between the passive-phone and no activity conditions. There were no differences in heart rate variability between the three conditions. The effects of texting on mood, self-reported stress, and heart rate variability did not differ by gender.ConclusionsBoth boys and girls may benefit from texting a friend after experiencing a stressful event.  相似文献   
74.
We report molecular evidence of Tula virus infection in an immunocompetent patient from Germany who had typical signs of hantavirus disease. Accumulating evidence indicates that Tula virus infection, although often considered nonpathogenic, represents a threat to human health.  相似文献   
75.
Parathyroid hormone (PTH) is produced by the parathyroid glands in response to low serum calcium concentrations where it targets bones, kidneys, and indirectly, intestines. The N-terminus of PTH has been investigated for decades for its ability to stimulate bone formation when administered intermittently (iPTH) and is used clinically as an effective anabolic agent for the treatment of osteoporosis. Despite great interest in iPTH and its clinical use, the mechanisms of PTH action remain complicated and not fully defined. More than 70 gene targets in more than 90 murine models have been utilized to better understand PTH anabolic actions. Because murine studies utilized wild-type mice as positive controls, a variety of variables were analyzed to better understand the optimal conditions under which iPTH functions. The greatest responses to iPTH were in male mice, with treatment starting later than 12 weeks of age, a treatment duration lasting 5–6 weeks, and a PTH dose of 30–60 μg/kg/day. This comprehensive study also evaluated these genetic models relative to the bone formative actions with a primary focus on the trabecular compartment revealing trends in critical genes and gene families relevant for PTH anabolic actions. The summation of these data revealed the gene deletions with the greatest increase in trabecular bone volume in response to iPTH. These included PTH and 1-α-hydroxylase (Pth;1α(OH)ase, 62-fold), amphiregulin (Areg, 15.8-fold), and PTH related protein (Pthrp, 10.2-fold). The deletions with the greatest inhibition of the anabolic response include deletions of: proteoglycan 4 (Prg4, −9.7-fold), low-density lipoprotein receptor-related protein 6 (Lrp6, 1.3-fold), and low-density lipoprotein receptor-related protein 5 (Lrp5, −1.0-fold). Anabolic actions of iPTH were broadly affected via multiple and diverse genes. This data provides critical insight for future research and development, as well as application to human therapeutics. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).  相似文献   
76.
Background/PurposeThis study aimed to compare preoperative management strategies for patients undergoing trephination for pilonidal disease and evaluate risk factors for recurrence.MethodsA retrospective review was performed of children undergoing index surgical treatment with trephination for pilonidal disease between September 2017 and April 2019. Intraoperative and postoperative management were standardized. Demographic and perioperative data were collected and analyzed.ResultsOne-hundred twenty patients were identified with a median follow-up time of 7.5 months (interquartile range 4.1–13.2 months). Overall, 24 (20%) patients had a postoperative recurrence of pilonidal disease. Patients with multiple preoperative surgery clinic visits were less likely to have recurrent disease compared to those seen only once preoperatively (11% vs 26%, p = 0.040). Compared to patients without recurrence, those who recurred went to the operating room sooner from the time of initial surgical consultation (32 days vs 54 days, p < 0.001). Perioperative antibiotics, history of acute infection, and prior drainage procedures were not risk factors for recurrence.ConclusionsMultiple preoperative clinic visits are associated with a lower recurrence rate in children undergoing trephination for pilonidal disease. An increased duration of preoperative medical management may be responsible for this finding. Prospective study is needed to confirm these findings and identify additional factors that influence recurrence.Type of StudyTreatment Study.Level of EvidenceIII (Retrospective Comparative).  相似文献   
77.
For women with breast cancer in whom multiple Oncotype DX® Recurrence Scores (RS) are obtained, RS concordance utilizing current NCCN recommendations has not been evaluated. Patients with two or more RS were identified. RS were stratified by NCCN guidelines and compared for concordance. Twenty-four patients were evaluated. RS concordance varied by tumor type: 100% in the same tumor, 91.7% in multiple ipsilateral tumors, 71.4% in contralateral tumors, and 66.7% in in-breast recurrent tumors. RS concordance for multiple assays in the same patient is not high enough to omit Oncotype DX® testing for each tumor.  相似文献   
78.
BackgroundA psychosocial evaluation is an important component of the preoperative assessment process for people seeking metabolic and bariatric surgery (MBS), and is required for accreditation of MBS programs. Recently, independent companies without affiliations with MBS programs have been marketing remotely administered, unaffiliated psychosocial evaluations for MBS (RUS), and American Society for Metabolic and Bariatric Surgery (ASMBS) members have raised concerns about these evaluations.ObjectivesTo explore ASMBS members’ beliefs about RUS.SettingOnline survey.MethodsWe developed a survey to evaluate ASMBS members’ opinions, experiences, and/or concerns about in-person and RUS psychosocial evaluations for MBS.ResultsIn total, 635 ASMBS members responded to the online survey and 156 responded to an open-ended question on RUS. Responses were coded based on a manual developed for this study, yielding themes of concerns about the quality of RUS, lack of ongoing relationships in RUS, and conditions under which/reasons why RUS evaluations could be acceptable.ConclusionRespondents expressed both interest in and concerns about RUS in pre-MBS psychosocial evaluations. Use of RUS has the potential to improve access to MBS by providing a convenient and efficient means of completing the psychosocial evaluation. Conversely, respondents expressed concerns about the background and training of RUS providers, the quality of the reports, and the limited relationships between the RUS provider and both the MBS patient and the MBS team. We discuss the clinical and research implications of response themes, particularly for patients in rural areas or those who have other barriers to care.  相似文献   
79.
ObjectivesThe objective of this study was to assess the performance of models of primary healthcare (PHC) delivered in First Nation and adjacent communities in Manitoba, using hospitalization rates for ambulatory care sensitive conditions (ACSC) as the primary outcome.MethodsWe used generalized estimating equation logistic regression on administrative claims data for 63 First Nations communities from Manitoba (1986–2016) comprising 140,111 people, housed at the Manitoba Centre for Health Policy. We controlled for age, sex, and socio-economic status to describe the relationship between hospitalization rates for ACSC and models of PHC in First Nation communities.ResultsHospitalization rates for acute, chronic, vaccine-preventable, and mental health-related ACSCs have decreased over time in First Nation communities, yet remain significantly higher in First Nations and remote non-First Nations communities as compared with other Manitobans. When comparing different models of care, hospitalization rates were historically higher in communities served by health centres/offices, whether or not supplemented by itinerant medical services. These rates have significantly declined over the past two decades.ConclusionLocal access to a broader complement of PHC services is associated with lower rates of avoidable hospitalization in First Nation communities. The lack of these services in many First Nation communities demonstrates the failure of the current Canadian healthcare system to meet the need of First Nation peoples. Improving access to PHC in all 63 First Nation communities can be expected to result in a reduction in ACSC hospitalization rates and reduce healthcare cost.  相似文献   
80.
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