全文获取类型
收费全文 | 2823篇 |
免费 | 275篇 |
国内免费 | 264篇 |
专业分类
3362篇 |
出版年
2024年 | 28篇 |
2023年 | 105篇 |
2022年 | 151篇 |
2021年 | 182篇 |
2020年 | 200篇 |
2019年 | 196篇 |
2018年 | 159篇 |
2017年 | 182篇 |
2016年 | 169篇 |
2015年 | 171篇 |
2014年 | 152篇 |
2013年 | 201篇 |
2012年 | 175篇 |
2011年 | 126篇 |
2010年 | 100篇 |
2009年 | 119篇 |
2008年 | 125篇 |
2007年 | 130篇 |
2006年 | 104篇 |
2005年 | 123篇 |
2004年 | 90篇 |
2003年 | 59篇 |
2002年 | 59篇 |
2001年 | 60篇 |
2000年 | 20篇 |
1999年 | 37篇 |
1998年 | 17篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 17篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有3362条查询结果,搜索用时 0 毫秒
91.
目的:评估财经类院校贫困生心理状况,探讨财经类院校贫困生的心理状况与述情障碍的关系,为更好解决贫困生的心理问题提供依据。方法:对298名贫困学生进行症状自评量表(SymptomChecklist-90,SCL-90)多伦多述情障碍量表(Twenty-ItemTorontoAlexithymiaScale,TAS.20)的测量并与320名非贫困生对照组的结果进行比较。结果:①贫困生组的抑郁、焦虑、人际关系敏感、精神病性、偏执因子分及SCL.90总分因子高于对照组,贫困生组的F1因子明显高于对照组;②述情障碍组SCL-90总分和各因子得分明显高于非述情组;③述情量表总分及各因子分与症状自评量表总分及各因子分显著相关(P〈0.01或P〈0.05)。结论:①与非贫困学生相比,贫困生具有较多的心身症状,主要表现在抑郁、焦虑、人际关系敏感、精神病性、偏执。②述情障碍与心理健康密切相关,述情障碍个体倾向于更容易出现心身症状。③F1(缺乏识别情感的能力)是一个较其它因子更敏感的述情障碍的鉴定指标。 相似文献
92.
Iodine deficiency is a factor that may compromise child development, but is not the only one. Other health determinants, some of them outside the healthcare system, are able to influence development. Fighting iodine deficiency may be a pragmatic and useful strategy if it is found to be not maleficent, beneficial to health, and cost-effective, and does not make us lose the notion that child development goes beyond psychomotor or cognitive performance. This article analyzes such constraints from a critical point of view. 相似文献
93.
目的:调查入伍新兵心理卫生服务状况及对心理卫生服务的需求。方法:采用质性研究和量性研究相结合的方法,对42名入伍新兵作半结构性访谈,编制《部队心理卫生服务状况和需求》调查表,采用调查表对1609名新兵进行调查。结果:9.4%的新兵心理健康知识比较了解;接近半数新兵(43.5%)对心理健康知识很感兴趣;新兵获取心理知识的途径依次为网络、心理知识讲座、报刊杂志、广播电视、面对面咨询;新兵最期望获得的心理知识依次为如何调节自己的情绪、如何建立良好的人际关系、如何塑造自己的个性和常见的心理障碍表现;新兵认为最有帮助的心理服务形式依次为一对一心理咨询、心理知识讲座、心理测验和团体心理活动;只有7.7%的新兵接受过心理卫生服务。结论:新兵对心理健康知识感兴趣,但认知度和利用度均较低,应通过网络、心理知识讲座等方式普及新兵需要的心理健康知识。 相似文献
94.
Synthetic biology (SynBio) is a global endeavour with research and development programs in many countries, and due (in part) to its multi-use characteristics it has potential to improve global health in the area of vaccine development, diagnostics, drug synthesis, and the detection and remediation of environmental toxins. However, SynBio will also concurrently require global governance. Here we present what we have learnt from the articles in this Special Issue, and the workshop we hosted in The Hague in February of 2012 on SynBio, global health, and global governance that generated many of the papers appearing here. Importantly we take the notion of ‘responsible research and innovation’ as a guiding perspective. In doing so our understanding of governance is one that shifts its focus from preventing risks and other potential negative implications, and instead is concerned with institutions and practices involved in the inclusive steering of science and technology towards socially desirable outcomes. We first provide a brief overview of the notion of global health, and SynBio’s relation to global health issues. The core of the paper explores some of the dynamics involved in fostering SynBio’s global health pursuits; paying particular attention to of intellectual property, incentives, and commercialization regimes. We then examines how DIYbio, Interactive Learning and Action, and road-mapping activities can be seen as positive and productive forms of governance that can lead to more inclusive SynBio global health research programs. 相似文献
95.
《Revista espa?ola de geriatría y gerontología》2020,55(5):272-278
ObjectivesTo analyze differences by age group in anxiety, depression, loneliness and comorbid anxiety and depression in young people, middle aged adults and older adults during the lock-down period at home due to the COVID-19 pandemic, and to explore the association between negative self-perceptions of aging and psychological symptoms controlling by age group.MethodParticipants are 1501 people (age range 18 to 88 years). Anxiety, sadness, loneliness and self-perceptions of aging were assessed. The sample was divided according to the age group and quartiles (lower, intermediate levels, and higher) of anxiety, sadness, loneliness and self-perceptions of aging.ResultsOlder adults reported lower levels of anxiety and sadness than middle aged adults, and middle aged adults reported lower levels than younger participants. Middle aged adults reported the lowest loneliness, followed by older adults and younger participants. For each age group, those with more negative self-perceptions of aging reported higher anxiety, sadness and loneliness. More comorbid anxiety and sadness was found in younger adults and less in older adults; more depressed participants in the middle aged group, and more older adults and less younger participants were found in the group with the lowest levels of anxiety and sadness. For all the age groups, participants with high levels of comorbid anxiety and sadness are those who report the highest scores in negative self-perceptions of aging.ConclusionsOlder adults reported lower psychological anxiety, sadness and loneliness than the other age groups. Having negative self-perceptions of aging damage psychological health irrespective of the chronological age. 相似文献
96.
1. The ideal conditions for a parasite are typically found with its preferred host. However, prior to transmission to a naïve host and successful infection, a parasite may have to withstand extrinsic environmental conditions. Some parasites have adapted to time away from hosts, for example, by co-opting vectors or by having drought-resistant growth stages. However, other parasites may have no obvious adaptations to persist during prolonged transmission cycles. Consequently, the environment may detrimentally impact parasite fitness and ultimately epidemiology. 2. Here, we investigate the impact of nectar-realistic sugar concentrations on the ability of the trypanosome parasite Crithidia bombi, which may be transmitted between conspecifics at flowers, to infect its bumblebee host Bombus terrestris and to reproduce during the infection (parasitaemia). Our results show, following 30 min exposure to our experimental nectars that as sugar concentration increases, infection prevalence and parasitaemia decrease. This is likely due to the increased osmotic stress C. bombi experiences in high sugar, aqueous environments. 3. Consequently, if C. bombi transmission is facilitated by nectar or a high-sugar environment, it may have a negative impact on parasite fitness. 相似文献
97.
Nour Makarem Jacob Paul Elsa-Grace V. Giardina Ming Liao 《Chronobiology international》2020,37(5):673-685
ABSTRACT Chronotype reflects time of day preferences for performing daily activities. Previous research within Asian and European cohorts indicates evening chronotype is associated with elevated cardiometabolic risk. However, evidence is limited from population-based US cohorts, particularly among women in whom evening chronotype prevalence may become higher after middle-age, coinciding with life stages associated with higher cardiovascular disease (CVD) risk. This cross-sectional study evaluated associations of chronotype with overall cardiovascular health (CVH), health behaviors, and cardiometabolic risk factors among 506 women (mean age = 37 ± 16y, 62% racial/ethnic minority) in the American Heart Association (AHA)’s Go Red for Women Strategically-Focused Research Network cohort at Columbia University (New York City, NY, USA). Chronotype was assessed using the validated Morningness-Eveningness Questionnaire (MEQ) and categorized as “evening”, “intermediate”, and “morning” chronotypes. Health behaviors (diet, physical activity, and sleep) were assessed using validated questionnaires. Anthropometrics, clinical blood pressure, and blood biomarkers were assessed at the clinic visit. CVH was evaluated using the AHA Life’s Simple 7 (LS7) metrics; LS7 scores of 0–8 and 9–14 were considered indicative of poor and moderate-to-high CVH, respectively. Linear and logistic regression models adjusted for age, race/ethnicity, education, health insurance, and menopausal status were used to examine associations of MEQ scores and chronotype categories with overall CVH, clinical cardiometabolic risk factors, and health behaviors. Overall, 13% of women identified as evening chronotypes, while 55% and 32% reported being intermediate and morning types. In linear models, higher MEQ scores were associated with higher AHA LS7 scores (β(SE) = 0.02(0.01); p = .014), indicative of more favorable CVH, and with health behaviors not included in the LS7. Higher MEQ scores were also associated with lower Pittsburgh Sleep Quality Index, i.e. better sleep quality, (β(SE) = ?0.07(0.02), p < .0001), lower insomnia severity (β(SE) = ?0.14(0.01), p < .0001), shorter time to fall asleep (β(SE) = ?0.28(0.14), p = .044), and less sedentary time (β(SE) = ?0.11(0.03), p = .001). In logistic regression models, evening chronotype, compared to intermediate/morning type, was associated with higher odds of having poor CVH (OR(95%CI):2.41(1.20–4.85)), not meeting AHA diet (OR(95%CI):2.89(1.59–5.23)) and physical activity guidelines (OR(95%CI):1.78(1.03–3.07)), and having short sleep (OR(95%CI):2.15(1.24–3.73)) or insomnia (OR(95%CI):2.69(1.53–4.75)). The evening type compared to morning type was also associated with being a current smoker (OR(95%CI):2.14(1.02–4.52)) and having poor sleep quality (OR(95%CI:2.35(1.27–4.37)) and long sleep onset latency (OR(95%CI:1.89(1.00–3.56)). In our cohort of women, evening chronotype was related to poor CVH, likely driven by its influence on health behaviors. These findings, although warranting confirmation prospectively in other populations, suggest chronotype is an important factor to consider and possibly target when designing lifestyle interventions for CVD prevention. 相似文献
98.
Cristiane V. C. Nobre Ana M. M. Gomes Ana P. M. Gomes Antonio A. Gomes Ana P. C. Nascimento 《Gerodontology》2020,37(3):297-302
Objective: To evaluate the efficacy of electric and conventional toothbrushes for a group of elderly individuals. Background: Although the electric toothbrush has been recommended for elderly individuals, there had previously never been a study regarding its efficacy. Material and methods: Sixty independent elders of both genders with different oral conditions from the Center Adult Day Vitória, Espírito Santo, Brazil, were randomly divided into two groups of 30 individuals. One group received the Oral B CrossAction Power electric toothbrush, whereas the other received a conventional Bitufo Class 32 soft toothbrush to perform oral hygiene. The bacterial plaque index (O’Leary Plaque Index) and DMFT index were assessed as a measure of oral hygiene and oral health. The data were analysed using the Shapiro–Wilk, Mann–Whitney and Wilcoxon tests. Results: The results of the efficacy of the Oral B Cross Action Power electric toothbrush demonstrated that on the 7th and 15th days, the bacterial plaque indexes were 24.91 ± 12.81 and 22.11 ± 14.46, respectively, which corresponds to a 50.24% removal of bacterial plaque on the 7th and 55.83% on the 15th days. Although the electric toothbrush removed more bacterial plaque than the conventional toothbrush, the difference was not statistically significant. Conclusion: Both the conventional and the electric toothbrushes were effective in removing bacterial plaque within the elderly group. More studies are necessary to test the efficacy of electric toothbrushes in relation to conventional toothbrushes for elderly patients. 相似文献
99.