首页 | 官方网站   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   24427篇
  免费   2415篇
  国内免费   308篇
医药卫生   27150篇
  2024年   24篇
  2023年   340篇
  2022年   531篇
  2021年   948篇
  2020年   1151篇
  2019年   857篇
  2018年   763篇
  2017年   836篇
  2016年   931篇
  2015年   971篇
  2014年   2090篇
  2013年   2215篇
  2012年   2024篇
  2011年   2041篇
  2010年   1572篇
  2009年   1308篇
  2008年   1435篇
  2007年   1305篇
  2006年   1169篇
  2005年   948篇
  2004年   730篇
  2003年   632篇
  2002年   442篇
  2001年   337篇
  2000年   312篇
  1999年   190篇
  1998年   173篇
  1997年   153篇
  1996年   113篇
  1995年   76篇
  1994年   83篇
  1993年   58篇
  1992年   38篇
  1991年   51篇
  1990年   33篇
  1989年   31篇
  1988年   33篇
  1987年   35篇
  1986年   13篇
  1985年   23篇
  1984年   21篇
  1983年   25篇
  1982年   13篇
  1981年   14篇
  1980年   11篇
  1979年   13篇
  1978年   8篇
  1976年   9篇
  1975年   5篇
  1974年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
ABSTRACT

The Dominican Republic is thought to have significant epidemics of illicit drug use but lacks surveillance and formal analyses of the policy context of drug prevention and treatment services. We conducted an institutional ethnography of 15 drug service organisations in Santo Domingo and Boca Chica, Dominican Republic, to explore barriers and resources for drug abuse prevention and treatment. Here, we present a typology of drug service organisations based on their services, methods, and approach. We then draw on interviews with representatives of drug service institutions to describe the primary barriers to drug treatment and prevention services for drug users. We conclude with a focus on the policy priorities that could improve the conditions of health care for marginalised drug users in the Dominican Republic.  相似文献   
92.
ABSTRACT

Objectives: This paper is an examination of cancer/health communication factors (i.e. cancer/health information seeking, patient-provider communication (PPC), cancer screening information from providers) and screening for breast and cervical cancer among Asian Americans and five Asian ethnic groups (Chinese, Filipinos, Japanese, Koreans, Vietnamese) in comparison to Whites. Additionally, the relationship between cancer/health communication disparity and cancer screening gaps between Asian Americans and Whites was investigated.

Design: Data comes from a nationally representative sample of 2011–2014 Health Information National Trends Surveys (HINTS).

Results: Asian Americans and most Asian ethnic-groups reported significantly lower rates of cancer/health information seeking and lower evaluations for PPC as compared to Whites, though differences within Asian ethnic groups were observed (Koreans’ greater cancer/health information seeking, Japanese’ higher PPC evaluation). When the cancer/health communication factors were controlled, Asian Americans’ odds of cancer screening were increased. Especially, Asian Americans’ odds of adhering to the breast cancer screening guideline became nearly 1.4 times greater than Whites.

Conclusion: This research demonstrates that health organizations, providers, and Asian American patients’ collaborative efforts to increase the access to quality cancer information, to make culturally competent but straightforward screening recommendations, and to practice effective communication in medical encounters will contribute to diminishing cancer disparities among Asian Americans.  相似文献   
93.
随着我军新时期积极防御军事战略的实行,未来战争战场环境将愈发复杂与多样,部队所面临的饮用水水源与水质将更加复杂。我军现有饮用水安全检测、净化技术与装备还存在信息化、一体化程度不高,新型制取饮用水技术研究深度不够,以及对涉及国家安全的重要战略要地水资源现状有待进一步调研等情况。为能在各种特殊和恶劣条件下确保作战人员的饮水用安全,应建立国家战略水资源安全防护体系,加快水安全卫生装备信息化和全天候适应性研究,深入开展特殊环境下饮用水保障新技术研究。  相似文献   
94.
95.
Objective Many tasks in natural language processing utilize lexical pattern-matching techniques, including information extraction (IE), negation identification, and syntactic parsing. However, it is generally difficult to derive patterns that achieve acceptable levels of recall while also remaining highly precise.Materials and Methods We present a multiple sequence alignment (MSA)-based technique that automatically generates patterns, thereby leveraging language usage to determine the context of words that influence a given target. MSAs capture the commonalities among word sequences and are able to reveal areas of linguistic stability and variation. In this way, MSAs provide a systemic approach to generating lexical patterns that are generalizable, which will both increase recall levels and maintain high levels of precision.Results The MSA-generated patterns exhibited consistent F1-, F.5-, and F2- scores compared to two baseline techniques for IE across four different tasks. Both baseline techniques performed well for some tasks and less well for others, but MSA was found to consistently perform at a high level for all four tasks.Discussion The performance of MSA on the four extraction tasks indicates the method’s versatility. The results show that the MSA-based patterns are able to handle the extraction of individual data elements as well as relations between two concepts without the need for large amounts of manual intervention.Conclusion We presented an MSA-based framework for generating lexical patterns that showed consistently high levels of both performance and recall over four different extraction tasks when compared to baseline methods.  相似文献   
96.
97.
《Vaccine》2016,34(32):3663-3669
ObjectiveTo evaluate the potential impact and value of applications (e.g. adjusting ordering levels, storage capacity, transportation capacity, distribution frequency) of data from demand forecasting systems implemented in a lower-income country's vaccine supply chain with different levels of population change to urban areas.Materials and MethodsUsing our software, HERMES, we generated a detailed discrete event simulation model of Niger's entire vaccine supply chain, including every refrigerator, freezer, transport, personnel, vaccine, cost, and location. We represented the introduction of a demand forecasting system to adjust vaccine ordering that could be implemented with increasing delivery frequencies and/or additions of cold chain equipment (storage and/or transportation) across the supply chain during varying degrees of population movement.ResultsImplementing demand forecasting system with increased storage and transport frequency increased the number of successfully administered vaccine doses and lowered the logistics cost per dose up to 34%. Implementing demand forecasting system without storage/transport increases actually decreased vaccine availability in certain circumstances.DiscussionThe potential maximum gains of a demand forecasting system may only be realized if the system is implemented to both augment the supply chain cold storage and transportation. Implementation may have some impact but, in certain circumstances, may hurt delivery. Therefore, implementation of demand forecasting systems with additional storage and transport may be the better approach. Significant decreases in the logistics cost per dose with more administered vaccines support investment in these forecasting systems.ConclusionDemand forecasting systems have the potential to greatly improve vaccine demand fulfilment, and decrease logistics cost/dose when implemented with storage and transportation increases. Simulation modeling can demonstrate the potential health and economic benefits of supply chain improvements.  相似文献   
98.
The production of medical imaging is a continuing trend in healthcare institutions. Quality assurance for planned radiation exposure situations (e.g. X-ray, computer tomography) requires examination-specific set-ups according to several parameters, such as patient’s age and weight, body region and clinical indication. These data are normally stored in several formats and with different nomenclatures, which hinder the continuous and automatic monitoring of these indicators and the comparison between several institutions and equipment. This article proposes a framework that aggregates, normalizes and provides different views over collected indicators. The developed tool can be used to improve the quality of radiologic procedures and also for benchmarking and auditing purposes. Finally, a case study and several experimental results related to radiation exposure and productivity are presented and discussed.  相似文献   
99.
The spatial distribution of enteroparasitosis in an indigenous village from Paraná was evaluated to identify areas of risk for these infections. A cross-sectional study (from November 2010 to June 2011) was performed using Three Faecal Test® and Kato &; Katz method and a questionnaire on housing and hygiene conditions was administered. Local geostatistical analyses were performed to determine the spatial distribution of intestinal parasitic infections. The overall prevalence of enteroparasites was 67.2?% (457/680), and the most prevalent taxa were Ascaris lumbricoides (48.8?%) and Trichuris trichiura (44.7?%). The prevalence of heavy infection by soil-transmitted helminths was 3.6?% and the families lived in houses with an average of 5.1 residents and < 2 bedrooms per household. The average number of species per individual present spatial heterogeneity with the highest values (≥0.8) in areas with high clustering of residences. The visualization of the spatial distribution of intestinal parasites in this indigenous village is an important contribution to determining health risk areas and planning decisions and services.  相似文献   
100.
ObjectivesThe aim of this study was to investigate whether perceptions of the neighbourhood environment (NE) and objective measures of the NE were associated with frailty in older adults.MethodsA cross-sectional study in Adelaide, Australia, recruited a sample of 115 community-dwelling adults aged ≥60 years. Respondents’ perceptions of their NEs were assessed using the Neighbourhood Environment Walkability Scale (NEWS). An objective assessment of these NEWS survey questions was conducted using seven variables: residential density, land use mix diversity, street connectivity, accessibility, seasonal persistent green cover, road crash density and crime rate. Frailty was evaluated using the FRAIL (fatigue, resistance, ambulation, illnesses and loss of weight) scale. Multivariable linear regression analyses were employed to assess the associations between NEWS and frailty, and to assess the associations between objective neighbourhood variables and frailty.ResultsFrail and pre-frail older adults were more likely to live in areas with lower residential density, lower density of road crashes, and higher accessibility than robust participants. Additionally, a poorer perception of the overall environment, worse land-use mix and accessibility and worse crime safety were associated with frailty and pre-frailty after adjustment of covariates and objective GIS variables.DiscussionNeighbourhood characteristics, both objective and perceived, are associated with frailty levels in older adults, and that strategies to tackle frailty must consider the impact of the neighbourhood environment.  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-23

京公网安备 11010802026262号