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   2586篇
  免费   154篇
  2024年   7篇
  2023年   44篇
  2022年   36篇
  2021年   58篇
  2020年   86篇
  2019年   67篇
  2018年   146篇
  2017年   146篇
  2016年   135篇
  2015年   82篇
  2014年   101篇
  2013年   329篇
  2012年   211篇
  2011年   247篇
  2010年   136篇
  2009年   52篇
  2008年   199篇
  2007年   141篇
  2006年   146篇
  2005年   68篇
  2004年   61篇
  2003年   44篇
  2002年   37篇
  2001年   16篇
  2000年   28篇
  1999年   17篇
  1998年   8篇
  1997年   10篇
  1996年   5篇
  1994年   5篇
  1993年   5篇
  1992年   5篇
  1991年   4篇
  1990年   11篇
  1989年   6篇
  1988年   5篇
  1987年   5篇
  1986年   2篇
  1985年   3篇
  1982年   2篇
  1981年   2篇
  1978年   2篇
  1974年   3篇
  1973年   1篇
  1971年   2篇
  1969年   1篇
  1968年   3篇
  1967年   1篇
  1966年   3篇
  1965年   1篇
排序方式: 共有2740条查询结果,搜索用时 15 毫秒
171.
The European Union (EU) is strategically committed to the development of nanotechnology and its industrial exploitation. However, nanotechnology also has the potential to disrupt human health and the environment. The EU claims to be committed to the safe and responsible development of nanotechnology. In this sense, the EU has become the first governing body in the world to develop nanospecific regulations, largely due to legislative action taken by the European Parliament, which has compensated for the European Commission’s reluctance to develop special regulations for nanomaterials. Nevertheless, divergences aside, political bodies in the EU assume that nanotechnology development is controllable and take for granted that both the massive industrial use of nanomaterials and a high level of environmental and health protection are compatible. However, experiences such as the European controversy over agri-food biotechnology, which somewhat delegitimized the regulatory authority of the EU over technological safety and acceptability, arguably show that controllability assumptions are contestable on the grounds of alternative socio-economic and cultural preferences and values. Recently developed inclusive governance models on safety and innovation, such as “Responsible Research and Innovation” (RRI), widely claim that a diversity of considerations and issues are integrated into R&D processes. Even so, the possibility of more radically alternative constitutions of socio-technical safety seems to be seriously limited by the current ideology of innovation and economic imperatives of the global, knowledge-based, capitalist economy.  相似文献   
172.
The purpose of this longitudinal study is to examine the relationship between teen sexting and offline sexual behavior. Using a sample of 1134 Czech adolescents aged 10–18 (Mage = 13.84, SD = 1.94, girls = 58.8%) from 55 schools, the latent growth model of offline sexual behavior with sexting as a time-varying covariate was employed. Participants differed at baseline for offline sexual behavior at both individual and school levels, and they varied in the growth rate of offline sexual behavior at the individual level. Only age and sensation seeking explained the variability at baseline of offline sexual behavior. The positive association between sexting and offline sexual behavior was not constant across time. However, sexting at baseline predicted offline sexual behavior a half year and one year later. Sexting may be treated as a precursor of offline sexual behavior.  相似文献   
173.
Frontostriatal networks play critical roles in grounding action semantics and syntactic skills. Indeed, their atrophy distinctively disrupts both domains, as observed in patients with Huntington's disease (HD) and Parkinson's disease, even during early disease stages. However, frontostriatal degeneration in these conditions may begin up to 15 years before the onset of clinical symptoms, opening avenues for pre‐clinical detection via sensitive tasks. Such a mission is particularly critical in HD, given that patients’ children have 50% chances of inheriting the disease. Against this background, we assessed whether deficits in the above‐mentioned domains emerge in subjects at risk to develop HD. We administered tasks tapping action semantics, object semantics, and two forms of syntactic processing to 18 patients with HD, 19 asymptomatic first‐degree relatives, and sociodemographically matched controls for each group. The patients evinced significant deficits in all tasks, but only those in the two target domains were independent of overall cognitive state. More crucially, relative to controls, the asymptomatic relatives were selectively impaired in action semantics and in the more complex syntactic task, with both patterns emerging irrespective of the subjects’ overall cognitive state. Our findings highlight the relevance of these dysfunctions as potential prodromal biomarkers of HD. Moreover, they offer theoretical insights into the differential contributions of frontostriatal hubs to both domains while paving the way for innovations in diagnostic procedures.  相似文献   
174.
HIV testing is important in terms of prevention and treatment. However, HIV testing rates in the Spanish general population remains low. Therefore, HIV testing promotion constitutes a key issue. A high level of knowledge about HIV/AIDS is associated with having been tested for HIV. The general aim of this study was to determine the prevalence of people who had ever been tested for HIV in Spain. The sample consisted of 1,106 participants from the general population — 60.0% females and 40.0% males — aged between 17 and 55 years old. The assessment instruments were a questionnaire on sociodemographic data and HIV testing, a scale of knowledge about STIs and HIV/AIDS, and a scale of concern about STIs/HIV. Results showed that greater knowledge about STIs and HIV was associated with a greater likelihood of being tested for HIV (OR = .77; 95.0% CI = .73–.82; p < .05). In addition, higher concern about HIV/AIDS decreased the likelihood of not having been tested for HIV (OR = .87; 95.0% CI = .83–.92; p < .05). In fact, the higher participants concern about STIs was, the lower their likelihood of not having been tested for HIV was (OR = .87; 95.0% CI = .83–.91; p < .05). It is necessary to promote HIV testing in the general population as well as to consider their socio-demographic and psychological characteristics.  相似文献   
175.
The purpose of this study was to analyse the relationship between high social anxiety, academic goals and learning strategies in a sample of 2,022 (51.1% male) Spanish adolescents aged 12–16. The Social Phobia and Anxiety Inventory (SPAI), Achievement Goal Tendencies Questionnaire (AGTQ) and Learning and Studies Skills Strategies Inventory — High School Version (LASSI-HS) were used to assess the variables. The results showed no statistically significant differences in goal orientations between students with and without high social anxiety. However, students with high social anxiety used learning strategies significantly less. In addition, the logistic regression results indicated that high social anxiety acts as a significant predictor for setting social reinforcement goals and learning and study strategies.  相似文献   
176.
This article presents a brief history of the development of the Western university and the individuation of disciplines. It discusses the phenomenal specialization that has occurred since the 19th century, and the lack of correlative synthesis of the disparate fields of knowledge, which increasingly has come under critique. We explore the transdisciplinary experience that has been developing over the last few years in the University of Veracruz, in particular with regards to the Program for Transdisciplinarity, Dialogue of Knowing Styles and Sustainability, a co-construction of a set of actions that foster a transformation of university academics by means of deep dialogue and a transdisciplinary re-learning process.  相似文献   
177.
178.
179.
Work psychology has noted the importance of considering the temporal dimension of behavior in organizations. Given that society widely operates on a 24-hr schedule, it is important to know how circadian typologies are distributed in the general population. In this study, diurnal preference was analyzed among 4,175 Spanish participants (61.3% women), 12–59 years old, who completed the Composite Scale of Morningness (Smith, Reilly, & Midkiff, 1989). Several measurement models of the CSM were analyzed using exploratory structural equation modeling and confirmatory factor analysis. The bifactor model showed the best fit, with a general factor (morningness/eveningness) and three subfactors (morningness, morning affect, and time of retiring). The age and sex factorial invariance of the bifactor model were tenable at the latent variance-covariance level. Next, age and sex differences analysis indicated a progressive increase in morningness with age, but over 40 years old, men were more morningness oriented than women were. These results indicate that morningness/eveningness can be considered a multidimensional construct and that psychosocial factors must be considered when estimating the prevalence of morningness/eveningness in different populations or countries.  相似文献   
180.
The aim of this study was to describe civic patterns of engagement of Latino first- and secondgeneration (immigrant-origin) young adults and to provide insights into what differentiates these patterns. Based on 58 in-depth interviews with 18- to 25-year-olds of Dominican, Mexican, and Central American origin, the authors first established variations in different levels of civic engagement profiles. The authors then analyzed the characteristics that distinguish these civic profiles, considering demographic variables (generation, gender, education level, and undocumented status) as well as motivations for civic engagement. Two thirds of first- and second-generation participants were actively engaged, though variations in patterns emerged across civic profiles; undocumented status appeared a particularly salient driver of engagement. The authors found that rather than being instrumentally and individually motivated, Latino immigrant-origin young adults were primarily motivated to be civically engaged by social responsibility as well as by social (in)justices.  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