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   6401篇
  免费   551篇
  国内免费   22篇
耳鼻咽喉   59篇
儿科学   262篇
妇产科学   217篇
基础医学   875篇
口腔科学   92篇
临床医学   643篇
内科学   1300篇
皮肤病学   102篇
神经病学   713篇
特种医学   228篇
外科学   558篇
综合类   100篇
一般理论   9篇
预防医学   840篇
眼科学   151篇
药学   377篇
中国医学   8篇
肿瘤学   440篇
  2024年   22篇
  2023年   175篇
  2022年   250篇
  2021年   515篇
  2020年   286篇
  2019年   352篇
  2018年   322篇
  2017年   234篇
  2016年   246篇
  2015年   266篇
  2014年   309篇
  2013年   364篇
  2012年   490篇
  2011年   398篇
  2010年   245篇
  2009年   188篇
  2008年   267篇
  2007年   314篇
  2006年   241篇
  2005年   214篇
  2004年   178篇
  2003年   145篇
  2002年   121篇
  2001年   35篇
  2000年   29篇
  1999年   41篇
  1998年   69篇
  1997年   57篇
  1996年   55篇
  1995年   38篇
  1994年   42篇
  1993年   35篇
  1992年   21篇
  1991年   30篇
  1990年   19篇
  1989年   31篇
  1988年   33篇
  1987年   35篇
  1986年   19篇
  1985年   24篇
  1984年   12篇
  1983年   16篇
  1982年   20篇
  1981年   14篇
  1980年   22篇
  1977年   19篇
  1976年   16篇
  1975年   11篇
  1972年   8篇
  1968年   7篇
排序方式: 共有6974条查询结果,搜索用时 18 毫秒
41.
42.
Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.   相似文献   
43.
A model for concordance in a binary measure that does not rely on the assumption of an underlying latent liability dichotomized about a threshold has been demonstrated for twin pairs [Hannah et al, 1983]. It is extended here to pedigrees of arbitrary structure by making an assumption that is, for small incidence rates, almost equivalent to postulating that relative risks are multiplicative. The model is applied to the workshop data to determine the extent to which the known structure of the simulated models can be recovered.  相似文献   
44.
Journal of Public Health - The purpose of this paper is to investigate the implementation of value-based care principles in the context of frailty in the perioperative process, highlighting the...  相似文献   
45.
Maternal and Child Health Journal - Adverse childhood experiences (ACEs) are associated with poor physical and mental health outcomes in pregnancy, prompting many care agencies to ask about ACEs as...  相似文献   
46.
BackgroundA growing number of states are turning to managed care arrangements to provide care to senior and disabled Medicaid beneficiaries. Despite their complex care needs, very little is known about the experience of these individuals in managed care.ObjectiveTo document experiences of a sample of aged and disabled Medicaid beneficiaries receiving long-term services and supports through managed care in Iowa and to assess whether these experiences changed over time.MethodsA purposive sample of 49 aged and disabled beneficiaries enrolled in one of seven HCBS waivers in Iowa was recruited in 2017. Telephone surveys were conducted in 2017 and 2019. A conventional content analysis was used to generate themes, which were then ranked by frequency proportions. Thematic frequencies were compared across waves among repeat respondents.ResultsContent analysis yielded seven themes in the following areas: system navigation; service approvals; provider relations; customer service; case management; perception of Iowa’s transition to managed care; and oversight. Concerns with service approvals was the most frequently reported theme and within this, issues related to changes in approved services or hours and quality of newly approved services comprised the largest number of references. Beneficiary concerns appeared to grow over time among respondents participating in both survey interview waves.ConclusionThe results of this study point to serious and persistent concerns related to access and quality of care under managed care for at least some HCBS waiver participants in Iowa, underscoring the need for a comprehensive evaluation of the program.  相似文献   
47.
ObjectiveTo measure the association between nursing home (NH) characteristics and Coronavirus Disease 2019 (COVID-19) prevalence among NH staff.DesignRetrospective cross-sectional study.Setting and ParticipantsCenters for Disease Control and Prevention COVID-19 database for US NHs between March and August 2020, linked to NH facility characteristics (LTCFocus database) and local COVID-19 prevalence (USA Facts).MethodsWe estimated the associations between NH characteristics, local infection rates, and other regional characteristics and COVID-19 cases among NH staff (nursing staff, clinical staff, aides, and other facility personnel) measured per 100 beds, controlling for the hospital referral regions in which NHs were located to account for local infection control practices and other unobserved characteristics.ResultsOf the 11,858 NHs in our sample, 78.6% reported at least 1 staff case of COVID-19. After accounting for local COVID-19 prevalence, NHs in the highest quartile of confirmed resident cases (413.5 to 920.0 cases per 1000 residents) reported 18.9 more staff cases per 100 beds compared with NHs that had no resident cases. Large NHs (150 or more beds) reported 2.6 fewer staff cases per 100 beds compared with small NHs (<50 beds) and for-profit NHs reported 0.8 fewer staff cases per 100 beds compared with nonprofit NHs. Higher occupancy and more direct-care hours per day were associated with more staff cases (0.4 more cases per 100 beds for a 10% increase in occupancy, and 0.7 more cases per 100 beds for an increase in direct-care staffing of 1 hour per resident day, respectively). Estimates associated with resident demographics, payer mix, or regional socioeconomic characteristics were not statistically significant.Conclusions and ImplicationsThese findings highlight the urgent need to support facilities with emergency resources such as back-up staff and protocols to reduce resident density within the facility, which may help stem outbreaks.  相似文献   
48.
We developed an assay that detects minus-strand RNA as a surrogate for actively replicating severe acute respiratory syndrome coronavirus 2. We detected minus-strand RNA in 41 persons with coronavirus disease up to 30 days after symptom onset. This assay might inform clinical decision-making about patient infectiousness.  相似文献   
49.
The coronavirus disease pandemic has highlighted the key role epidemiologic models play in supporting public health decision-making. In particular, these models provide estimates of outbreak potential when data are scarce and decision-making is critical and urgent. We document the integrated modeling response used in the US state of Utah early in the coronavirus disease pandemic, which brought together a diverse set of technical experts and public health and healthcare officials and led to an evidence-based response to the pandemic. We describe how we adapted a standard epidemiologic model; harmonized the outputs across modeling groups; and maintained a constant dialogue with policymakers at multiple levels of government to produce timely, evidence-based, and coordinated public health recommendations and interventions during the first wave of the pandemic. This framework continues to support the state’s response to ongoing outbreaks and can be applied in other settings to address unique public health challenges.  相似文献   
50.

It is critical to understand what happens when PrEP patients are lost-to-follow-up (LTFU) and, where appropriate, attempt to re-engage them in care with the goal of preventing future human immunodeficiency virus (HIV) acquisition. We evaluated the benefits and limitations of using text-based outreach to re-engage with LTFU PrEP patients and offer re-initiation of PrEP care. Using text-messaging, we surveyed San Francisco City Clinic patients who started PrEP from January 2015 to October 2019 and were LTFU by October 1, 2020. Our goals were to better understand (1) whether our patients remained on PrEP through another provider or source, (2) why patients choose to discontinue PrEP, and (3) whether text-based outreach could successfully re-engage such patients in care. Multiple-choice survey questions were analyzed quantitatively to determine the proportion of respondents selecting each option; free-text responses were analyzed qualitatively using an inductive approach to identify any additional recurring themes. Of 846 eligible survey recipients, 130 responded (overall response rate 15.4%). Forty-two respondents (32.3%) were still on PrEP through another provider while 88 (67.7%) were not. Common reasons for stopping PrEP included: COVID-19–related changes in sex life (32.3% of responses), concerns regarding side effects (17.7%), and the need to take a daily pill (8.3%). Free text responses revealed additional concerns regarding risk compensation. While 32 participants agreed to be contacted by City clinic staff for PrEP counseling, only 6 were reached by phone and none of the six subsequently restarted PrEP. We learned that text messaging is a possible approach to survey certain PrEP program participants to determine who is truly LTFU and off PrEP, and to better understand reasons for PrEP discontinuation. While such information could prove valuable as programs seek to address barriers to PrEP retention, efforts to improve acceptability and increase response rates would be necessary. We were less successful in re-engaging LTFU patients in PrEP care, suggesting that text-messaging may not be the optimal strategy for this purpose.

  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