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   3445篇
  免费   353篇
  国内免费   8篇
耳鼻咽喉   19篇
儿科学   186篇
妇产科学   73篇
基础医学   439篇
口腔科学   60篇
临床医学   377篇
内科学   532篇
皮肤病学   34篇
神经病学   200篇
特种医学   74篇
外科学   585篇
综合类   365篇
一般理论   3篇
预防医学   425篇
眼科学   40篇
药学   226篇
肿瘤学   168篇
  2021年   50篇
  2020年   40篇
  2019年   61篇
  2018年   74篇
  2017年   59篇
  2016年   56篇
  2015年   58篇
  2014年   81篇
  2013年   122篇
  2012年   162篇
  2011年   151篇
  2010年   72篇
  2009年   91篇
  2008年   127篇
  2007年   159篇
  2006年   145篇
  2005年   140篇
  2004年   151篇
  2003年   145篇
  2002年   164篇
  2001年   124篇
  2000年   175篇
  1999年   120篇
  1998年   61篇
  1997年   32篇
  1996年   35篇
  1995年   45篇
  1994年   50篇
  1993年   31篇
  1992年   63篇
  1991年   69篇
  1990年   55篇
  1989年   64篇
  1988年   65篇
  1987年   57篇
  1986年   40篇
  1985年   56篇
  1984年   29篇
  1983年   38篇
  1982年   25篇
  1979年   28篇
  1978年   30篇
  1977年   42篇
  1976年   27篇
  1975年   34篇
  1974年   33篇
  1973年   29篇
  1972年   26篇
  1971年   25篇
  1968年   21篇
排序方式: 共有3806条查询结果,搜索用时 375 毫秒
921.
Objectives. We assessed the relation of childhood sexual abuse (CSA), intimate partner violence (IPV), and depression to HIV sexual risk behaviors among Black men who have sex with men (MSM).Methods. Participants were 1522 Black MSM recruited from 6 US cities between July 2009 and December 2011. Univariate and multivariable logistic regression models were used.Results. Participants reported sex before age 12 years with someone at least 5 years older (31.1%), unwanted sex when aged 12 to 16 years (30%), IPV (51.8%), and depression (43.8%). Experiencing CSA when aged 12 to 16 years was inversely associated with any receptive condomless anal sex with a male partner (adjusted odds ratio [AOR] = 0.50; 95% confidence interval [CI] = 0.29, 0.86). Pressured or forced sex was positively associated with any receptive anal sex (AOR = 2.24; 95% CI = 1.57, 3.20). Experiencing CSA when younger than 12 years, physical abuse, emotional abuse, having been stalked, and pressured or forced sex were positively associated with having more than 3 male partners in the past 6 months. Among HIV-positive MSM (n = 337), CSA between ages 12 and 16 years was positively associated with having more than 3 male partners in the past 6 months.Conclusions. Rates of CSA, IPV, and depression were high, but associations with HIV sexual risk outcomes were modest.Despite significant medical advances, the HIV epidemic remains a health crisis in Black communities. The Black population represents only 14% of the total US population but accounted for 44% of all new HIV infection (68.9 of 100 000) in 2010.1 Black men who have sex with men (MSM) are disproportionately impacted by HIV compared with other racial/ethnic groups of MSM.1,2 Male-to-male sexual contact accounted for 72% of new infections among all Black men.1 Young Black MSM (aged 13–24 years) have a greater number of new infections than any other age or racial group among MSM.1 Researchers have been challenged with developing HIV prevention strategies for Black MSM.3–7 Higher frequencies of sexual risk behaviors, substance use, and nondisclosure of sexual identities do not adequately explain this disparity.8,9 High rates of sexually transmitted infections (STIs), which facilitate HIV transmission, and undetected or late diagnosis of HIV infection only partially explain disproportionate HIV rates.8Researchers have begun to examine a constellation of health factors that may contribute to HIV among MSM. For example, syndemic theory or the interaction of epidemics synergistically, such as intimate partner violence (IPV) and depression, may help explain HIV-related sexual risk behaviors among Black MSM.9 Childhood sexual abuse (CSA), IPV, and mental health disorders including depression may comprise such a constellation and warrant further exploration.Experiences of CSA have been identified as being associated with negative sexual health outcomes, with MSM reporting higher CSA rates than the general male population.10–12 Men with CSA experiences are more likely than men without CSA experiences to engage in high-risk sexual behaviors,13–21 have more lifetime sexual partners,13–16 use condoms less frequently,13,14,16 and have higher rates of STIs,13,14,17 exchanging sex for drugs or money,13,14,17 HIV,13,14 alcohol and substance use,13–21 and depression.13–15,18,21 Such findings suggest that sexual risk reduction counseling may need to be tailored for MSM with CSA experiences.15Childhood sexual abuse histories have also been correlated with sexual revictimization, including IPV.22–24 One study with population-based estimates of CSA found that gay and bisexually identified men had higher odds of reporting CSA (9.5 and 12.8, respectively) compared with heterosexual men.25 For sexual minority men, CSA histories were associated with higher HIV and STI incidence.25 However, research examining CSA, revictimization, and sexual risk behaviors is lacking among Black MSM.In one existing study, Black and Latino MSM with CSA histories identified their trauma experiences as influencing their adult sexual decision-making.26 Among Black MSM in 2 additional studies, emotional distress and substance use were attributed to having CSA experiences (Leo Wilton, PhD, written communication, October 2, 2013).27 In an ethnically diverse sample of 456 HIV-positive MSM, CSA was associated with insertive and receptive condomless anal sex.19Similar to CSA, IPV has not been extensively examined among MSM or Black MSM,28 but may be associated with sexual risk behaviors. Intimate partner violence is defined as a pattern of controlling, abusive behavior within an intimate relationship that may include physical, psychological or emotional, verbal, or sexual abuse.29 Little research exists on IPV among same-sex couples despite incidence rates being comparable to or greater than that of heterosexual women.28,30–34 Important IPV information comes from the National Intimate Partner and Sexual Violence Survey, a nationally representative survey for experiences of sexual violence, stalking, and IPV among men and women in the United States.28 Among men who experienced rape, physical violence, or stalking by an intimate partner, perpetrator differences by gender were found among gay, bisexual, and heterosexual men; 78% of bisexual and 99.5% of heterosexual men reported having only female perpetrators, and 90.7% of gay men reported having only male perpetrators.28 Being slapped, pushed, or shoved by an intimate partner during their lifetime was reported by gay (24%), bisexual (27%), and heterosexual (26.3%) men.28Intimate partner violence has been linked to condomless anal sex, HIV infection, substance use, CSA, and depression.35–37 Being an HIV-positive MSM has been linked with becoming a victim of IPV.38,39 Welles et al. found that being an African American MSM who initially disclosed having male partners and early life sexual abuse experiences was associated with IPV victimization.39 Wilton found that a high percentage of Black MSM reported IPV histories: emotional abuse (48.3%), physical abuse (28.3%), sexual abuse (21.7%), and stalking abuse (29.2%; Leo Wilton, PhD, written communication, October 2, 2013). Such findings lend to the importance of exploring, both independently and together, the association of CSA and IPV with sexual risk behaviors.Some studies have reported the influence of mental health (e.g., depression) on sexual risk behaviors among MSM,9,40,41 whereas others have not corroborated such findings.42 Greater rates of depression among MSM than among non-MSM samples43–45 and elevated rates of depression and anxiety among Black MSM have been reported.46 The Urban Men’s Health Study, a cross-sectional sample of MSM in 4 US cities, did not find a significant relationship between high depressive symptoms and condomless anal sex.42 However, the EXPLORE study, a randomized behavioral intervention for MSM in 6 US cities, supported the association between moderate depressive symptoms and an increased risk for HIV infection.47 Moderate levels of depression and higher rates of sexual risk were also reported for HIV-infected MSM over time.48 Another study conducted with 197 Black MSM found that moderate depressive symptoms were associated with having condomless anal sex with a serodiscordant casual partner.49 These mixed findings support the need to better understand the relationship between the severity of depression (i.e., moderate vs severe) and HIV risk behaviors.The HIV Prevention Trials Network 061 study, also known as the BROTHERS (Broadening the Reach of Testing, Health Education, Resources, and Services) Project, was a multisite study to determine the feasibility and acceptability of a multicomponent intervention for Black MSM. The current analysis aims to assess the prevalence of CSA, IPV, and depressive symptomology, and examine the relationships between these factors and insertive and receptive condomless anal sex and number of sexual partners in a large cohort of Black MSM.  相似文献   
922.

Objective

Economic measures such as unemployment and gross domestic product are correlated with changes in health outcomes. We aimed to examine the effects of changes in government healthcare spending, an increasingly important measure given constrained government budgets in several European Union countries.

Design

Multivariate regression analysis was used to assess the effect of changes in healthcare spending as a proportion of total government expenditure, government healthcare spending as a proportion of gross domestic product and government healthcare spending measured in purchasing power parity per capita, on five mortality indicators. Additional variables were controlled for to ensure robustness of data. One to five year lag analyses were conducted.

Setting and Participants

European Union countries 1995–2010.

Main outcome measures

Neonatal mortality, postneonatal mortality, one to five years of age mortality, under five years of age mortality, adult male mortality, adult female mortality.

Results

A 1% decrease in government healthcare spending was associated with significant increase in all mortality metrics: neonatal mortality (coefficient −0.1217, p = 0.0001), postneonatal mortality (coefficient −0.0499, p = 0.0018), one to five years of age mortality (coefficient −0.0185, p = 0.0002), under five years of age mortality (coefficient −0.1897, p = 0.0003), adult male mortality (coefficient −2.5398, p = 0.0000) and adult female mortality (coefficient −1.4492, p = 0.0000). One per cent decrease in healthcare spending, measured as a proportion of gross domestic product and in purchasing power parity, was both associated with significant increases (p < 0.05) in all metrics. Five years after the 1% decrease in healthcare spending, significant increases (p < 0.05) continued to be observed in all mortality metrics.

Conclusions

Decreased government healthcare spending is associated with increased population mortality in the short and long term. Policy interventions implemented in response to the financial crisis may be associated with worsening population health.  相似文献   
923.
The Australian health system is generally well prepared for mass casualty events. Fortunately, there have been very few terrorist attacks and these have involved low numbers of casualties compared with events overseas. Nevertheless, Australian health professionals need to be prepared to treat mass casualties with blast and ballistic trauma. The US military and its allies including Australia have had extensive experience with mass casualty management in the Middle East and Afghanistan wars for more than a decade. To define their experience, they developed the Tactical Combat Casualty Care Guidelines that have saved many lives. It is now prudent to incorporate this knowledge and experience into civilian practice in Australia.  相似文献   
924.

Background

Gay, bisexual, and other men who have sex with men (MSM) account for a disproportionate burden of new HIV infections in the United States. Mobile technology presents an opportunity for innovative interventions for HIV prevention. Some HIV prevention apps currently exist; however, it is challenging to encourage users to download these apps and use them regularly. An iterative research process that centers on the community’s needs and preferences may increase the uptake, adherence, and ultimate effectiveness of mobile apps for HIV prevention.

Objective

The aim of this paper is to provide a case study to illustrate how an iterative community approach to a mobile HIV prevention app can lead to changes in app content to appropriately address the needs and the desires of the target community.

Methods

In this three-phase study, we conducted focus group discussions (FGDs) with MSM and HIV testing counselors in Atlanta, Seattle, and US rural regions to learn preferences for building a mobile HIV prevention app. We used data from these groups to build a beta version of the app and theater tested it in additional FGDs. A thematic data analysis examined how this approach addressed preferences and concerns expressed by the participants.

Results

There was an increased willingness to use the app during theater testing than during the first phase of FGDs. Many concerns that were identified in phase one (eg, disagreements about reminders for HIV testing, concerns about app privacy) were considered in building the beta version. Participants perceived these features as strengths during theater testing. However, some disagreements were still present, especially regarding the tone and language of the app.

Conclusions

These findings highlight the benefits of using an interactive and community-driven process to collect data on app preferences when building a mobile HIV prevention app. Through this process, we learned how to be inclusive of the larger MSM population without marginalizing some app users. Though some issues in phase one were able to be addressed, disagreements still occurred in theater testing. If the app is going to address a large and diverse risk group, we cannot include niche functionality that may offend some of the target population.  相似文献   
925.
926.
Pancreatic surgery is still associated with a relatively high morbidity and mortality compared with other specialties. This is a result of the complex nature of the organ, the difficult access as a result of the retroperitoneal position and the number of technically challenging anastomoses required. Nevertheless, the past two decades have witnessed a steady improvement in morbidity and a decrease in mortality achieved through alterations of technique (particularly relating to the pancreatic anastomoses) together with hormonal manipulation to decrease pancreatic secretions.Recently minimally invasive pancreatic surgery has been attempted by several centres around the world which has stimulated considerable interest in this approach. The majority of the cases attempted have been distal pancreatectomies, because of the more straightforward nature of the resection and the lack of a pancreatic ductal anastomosis, but more recently reports of laparoscopic pancreaticoduodenectomy have started to appear.The reports of the series to date have been difficult to interpret and although the results are claimed to be equivalent or better than those associated with a traditional approach a careful examination of the literature and comparison with the best results previously reported does not presently support this. In the present review we examined all the reports of pancreatic procedures performed laparoscopically and compared the results with those previously achieved at open surgery.  相似文献   
927.
Pancreatic exocrine insufficiency (PEI) occurs when the amounts of enzymes secreted into the duodenum in response to a meal are insufficient to maintain normal digestive processes. The main clinical consequence of PEI is fat maldigestion and malabsorption, resulting in steatorrhoea. Pancreatic exocrine function is commonly assessed by conducting a 3-day faecal fat test and by measuring levels of faecal elastase-1 and serum trypsinogen. Pancreatic enzyme replacement therapy is the mainstay of treatment for PEI. In adults, the initial recommended dose of pancreatic enzymes is 25,000 units of lipase per meal, titrating up to a maximum of 80,000 units of lipase per meal. In infants and children, the initial recommended dose of pancreatic enzymes is 500 units of lipase per gram of dietary fat; the maximum daily dose should not exceed 10,000 units of lipase per kilogram of bodyweight. Oral pancreatic enzymes should be taken with meals to ensure adequate mixing with the chyme. Adjunct therapy with acid-suppressing agents may be useful in patients who continue to experience symptoms of PEI despite high-dose enzyme therapy. A dietitian experienced in treating PEI should be involved in patient management. Dietary fat restriction is not recommended for patients with PEI. Patients with PEI should be encouraged to consume small, frequent meals and to abstain from alcohol. Medium-chain triglycerides do not provide any clear nutritional advantage over long-chain triglycerides, but can be trialled in patients who fail to gain or to maintain adequate bodyweight in order to increase energy intake.  相似文献   
928.
Couples-based voluntary HIV counseling and testing (CVCT) allows couples to receive their HIV test results together and has been demonstrated to be effective in reducing HIV transmission, increasing and sustaining condom use, and reducing sexual risk-taking among at-risk heterosexual couples. However, the acceptability of CVCT among MSM has yet to be evaluated in an African setting. The results from seven focus group discussions and 29 in-depth interviews conducted in Cape Town, South Africa exhibit overwhelmingly high acceptance of CVCT. Participants were attracted to the counseling components of the service, stating that these would allow for the couple to increase their commitment and to explore methods of how to effectively reduce their risk of acquiring or transmitting HIV in the presence of a trained counselor. These results suggest CVCT would be highly welcomed and could work to fill the significant lack of services available and accessible to MSM couples in Cape Town.  相似文献   
929.
930.
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