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   890篇
  免费   82篇
  国内免费   5篇
耳鼻咽喉   7篇
儿科学   31篇
妇产科学   32篇
基础医学   75篇
口腔科学   3篇
临床医学   159篇
内科学   165篇
皮肤病学   15篇
神经病学   86篇
特种医学   7篇
外科学   122篇
综合类   5篇
预防医学   125篇
眼科学   4篇
药学   65篇
肿瘤学   76篇
  2023年   9篇
  2022年   8篇
  2021年   45篇
  2020年   18篇
  2019年   41篇
  2018年   39篇
  2017年   42篇
  2016年   28篇
  2015年   34篇
  2014年   48篇
  2013年   59篇
  2012年   86篇
  2011年   83篇
  2010年   47篇
  2009年   37篇
  2008年   58篇
  2007年   57篇
  2006年   47篇
  2005年   45篇
  2004年   54篇
  2003年   26篇
  2002年   34篇
  2001年   5篇
  2000年   2篇
  1999年   3篇
  1998年   2篇
  1997年   2篇
  1996年   3篇
  1995年   3篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1985年   1篇
  1983年   1篇
  1981年   1篇
  1980年   1篇
排序方式: 共有977条查询结果,搜索用时 15 毫秒
91.
92.
INTRODUCTION: The purpose of this study was to allow mothers who are at high risk for abusing their child to describe how they manage when their infant cries. METHOD: This phenomenologic qualitative study used a focus group design and semi-structured interview format. Participants were seven low-income women with a child enrolled in an urban day care facility, which provided the setting for data collection. RESULTS: Analyses of the data revealed three themes: (a) activities done to pacify the infant, (b) coping mechanism, and (c) social support available. DISCUSSION: The results of this study indicate that activities (a) may include the infant, such as holding and singing, or (b) may be directed toward the mother, such as using headphones or leaving the room. These activities follow the guidelines of the American Academy of Pediatrics and are not unique. Social support primarily was provided at the day care facility, supplemented with personal relationships that are tentative. Valued informal and formal interactions with supportive persons provide the emotional and psychosocial support for this at-risk population.  相似文献   
93.
A retrospective study to determine the relationship between early microporous membrane oxygenator (MMO) failure and blood pressure at the MMO outlet (Pmo) was conducted using data collected with 19 dogs (22 +/- 1 kg, mean +/- SEM) undergoing routine normothermic cardiopulmonary bypass. Because gas flow was maintained at a high level, it could not be used to control CO2 exchange. Instead, blood PCO2 was controlled by adding CO2 to the sweep gas. Blood PO2 was controlled as suggested by the manufacturer, by adjusting the %O2 in the gas phase (g). Blood flow was 2575 +/- 54 ml/min; Pmo ranged from 173 to 790 mm Hg; and hematocrit was 33 +/- 1%. O2 exchange was calculated from blood gas parameters. Changes in the diffusion potential of O2 (delta PO2) and CO2 (delta PCO2) and MMO performance (P, taken as oxygen exchange normalized to a diffusion potential of 100 mm Hg) indicated MMO failure. Initial values, taken within 60 min of bypass initiation, were compared to final values taken at 226 +/- 9 min of bypass. Despite higher final delta PO2 (411 +/- 9 vs. 538 +/- 19 mm Hg, p less than 0.0001 paired t-test) and delta PCO2 (18.6 +/- 2.4 vs. 30.5 +/- 4.7 mm Hg, p less than 0.0017), arterial blood PO2 decreased (159 +/- 15 to 89 +/- 6 mm Hg, p less than 0.0005) and PCO2 increased (36.4 +/- 1.5 to 46.1 +/- 3.0 mm Hg, p less than 0.0039), and the performance decreased [24.5 +/- 1.1 to 20.1 +/- 0.7 (ml/min)/(100 mm Hg), p less than 0.0001].(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
94.
Neonates have a higher prevalence of bacterial sepsis and have greater morbidity and mortality from sepsis than other infants and children. Our understanding of the inflammatory and immunological responses to sepsis is hampered by the lack of appropriate neonatal murine models. In the present report, we have developed a cecal slurry model of generalized peritonitis in neonatal mice (age range, 5-7 days) and compared the outcome and the innate and adaptive cellular responses of these animals with those of the young adult animals (age range, 7-10 weeks) with sepsis induced either by cecal slurry administration or by cecal ligation and puncture. Neonatal mice were more susceptible to sepsis and mounted a markedly attenuated systemic inflammatory response compared with young adult animals (specifically, decreased plasma interferon gamma; interleukins 1alpha and 1beta; regulated on activation, normal T expressed and secreted (RANTES); and tumor necrosis factor alpha concentrations). Compared with young adult animals, septic neonatal mice did not lose significant percentage or absolute number of splenic CD4+ T cells. These findings suggest that the cecal slurry model of generalized peritonitis can produce sepsis in neonatal mice with dose-dependent lethality. Inherent differences in the host response to polymicrobial sepsis between neonatal and young adult animals may explain the increased sensitivity of the neonatal mouse to generalized peritonitis.  相似文献   
95.
BACKGROUND: Women in Canada, as in the rest of the world, represent an increasing proportion of new HIV positive cases. In 2002, women accounted for 25% of all positive HIV tests reported in Canada; with the majority being in their childbearing years (15 to 39 years), perinatal transmission of HIV in Canada is cause for concern. Following the development of interventions that can effectively reduce vertical transmission rate, prenatal screening of HIV has become the first and most pivotal step in the prevention of mother-to-child HIV transmission. The purpose of this study was to assess how women's knowledge and attitudes regarding HIV and HIV screening in pregnancy influence screening rates. METHOD: A prospective anonymous survey of 231 women attending antenatal care clinics at a teaching university hospital or in a community clinic was conducted. RESULTS: In general, pregnant women supported universal HIV screening in the prenatal period. Women who previously had been tested for HIV and who did not perceive that they were at risk for contracting HIV were more likely to decline HIV testing in their current pregnancy. Overall knowledge regarding HIV and its transmission is less than optimal, particularly among those women who declined HIV testing. CONCLUSION: Knowledge gaps exist between women accepting and declining prenatal HIV screening, particularly relating to benefits of screening. These results suggest that efforts have to continue to be put into educating the public but also, importantly, into changing current attitudes.  相似文献   
96.
The Australian National Poliovirus Reference Laboratory (NPRL), located within the Victorian Infectious Diseases Reference Laboratory, is the national laboratory for Australia, the Pacific Islands and Brunei Darussalam, and is accredited by the World Health Organization (WHO) as the Regional Reference Laboratory for the WHO Western Pacific Region. The NPRL, in collaboration with the Australian Paediatric Surveillance Unit, co-ordinates surveillance for acute flaccid paralysis (AFP), the major clinical presentation of poliovirus infection. After classification of AFP cases by the Polio Expert Committee, the non-polio AFP rate for Australia in 2006 was 1.1, meeting the WHO surveillance requirement of detecting more than one AFP case per 100,000 children aged less than 15 years. During 2006, 80 specimens were referred to the NPRL, 59 from AFP cases and 21 from other sources. Poliovirus type 3 was isolated from two patients without AFP and the isolates were characterised as Sabin-like using WHO accredited methodologies. Echovirus 30 was isolated from two cases of AFP and coxsackievirus B5 and adenovirus were isolated from individual cases. During 2006, 1,998 cases of poliomyelitis due to wild poliovirus infection were reported world-wide, of which, only 6.8% (127) were due to importation of wild poliovirus.  相似文献   
97.
The present study examined the influence of maternal and child characteristics on parenting behaviors in a genetically informative study. The participants were 976 twins and their mothers from the Colorado Longitudinal Twin Study and the Twin Infant Project. Indicators of positive parenting were coded during parent–child interactions when twins were 7–36 months old. Child cognitive abilities and affection were independent correlates of positive parenting. There were significant gender differences in the magnitude of genetic and environmental influences on positive parenting, with shared environmental influences on parenting of girls and additive genetic influences on parenting of boys. Girls received significantly more positive parenting than boys. Differences in etiology of positive parenting may be explained by developmental gender differences in child cognitive abilities and affection, such that girls may have more rewarding interactions with parents, evoking more positive parenting.  相似文献   
98.
99.

Background

The relationship between physical heart failure (HF) symptoms and pathophysiological mechanisms is unclear.

Objective

To quantify the relationship between plasma β-adrenergic receptor kinase-1 (βARK1) and physical symptoms among adults with HF.

Methods

We performed a secondary analysis of data collected from two studies of adults with HF. Plasma βARK1 was quantified using an enzyme-linked immunosorbent assay. Physical symptoms were measured with the HF Somatic Perception Scale (HFSPS). Generalized linear modeling was used to quantify the relationship between βARK1 and HFSPS scores.

Results

The average age (n = 94) was 54.5 ± 13.1 years, 76.6% were male, and a majority (83.0%) had Class III or IV HF. βARK1 was significantly associated with HFSPS scores (β = 0.22 ± 0.10, p = 0.038), adjusting for other predictors of physical symptoms (model R2 = 0.250, F(7, 70) = 3.34, p = 0.004).

Conclusions

Higher βARK1 is associated with worse physical HF symptoms, pinpointing a potential pathophysiologic underpinning.  相似文献   
100.

Background

In spring 2020, U.S. universities closed campuses to limit the transmission of COVID-19, resulting in an abrupt change in residence, reductions in social interaction, and in many cases, movement away from a heavy drinking culture. The present mixed-methods study explores COVID-19-related changes in college student drinking. We characterize concomitant changes in social and location drinking contexts and describe reasons attributed to changes in drinking.

Methods

We conducted two studies of the impact of the COVID-19 pandemic on drinking behavior, drinking context, and reasons for both increases and decreases in consumption among college students. Study 1 (qualitative) included 18 heavy-drinking college students (Mage = 20.2; 56% female) who completed semi-structured interviews. Study 2 (quantitative) included 312 current and former college students who reported use of alcohol and cannabis (Mage = 21.3; 62% female) and who completed an online survey.

Results

In both studies, COVID-19-related increases in drinking frequency were accompanied by decreases in quantity, heavy drinking, and drunkenness. Yet, in Study 2, although heavier drinkers reduced their drinking, among non-heavy drinkers several indices of consumption increased or remained stable . Both studies also provided evidence of reductions in social drinking with friends and roommates and at parties and increased drinking with family. Participants confirmed that their drinking decreased due to reduced social opportunities and/or settings, limited access to alcohol, and reasons related to health and self-discipline. Increases were attributed to greater opportunity (more time) and boredom and to a lesser extent, lower perceived risk of harm and to cope with distress.

Conclusion

This study documents COVID-19-related changes in drinking among college student drinkers that were attributable to changes in context, particularly a shift away from heavy drinking with peers to lighter drinking with family. Given the continued threat of COVID-19, it is imperative for researchers, administrators, and parents to understand these trends as they may have lasting effects on college student drinking behaviors.
  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