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   3131882篇
  免费   242260篇
  国内免费   5221篇
耳鼻咽喉   45651篇
儿科学   98681篇
妇产科学   83191篇
基础医学   440635篇
口腔科学   90160篇
临床医学   284707篇
内科学   605158篇
皮肤病学   65988篇
神经病学   256694篇
特种医学   124641篇
外国民族医学   1082篇
外科学   474024篇
综合类   72340篇
现状与发展   2篇
一般理论   1231篇
预防医学   245850篇
眼科学   74179篇
药学   239026篇
  13篇
中国医学   6392篇
肿瘤学   169718篇
  2018年   32064篇
  2017年   24792篇
  2016年   27558篇
  2015年   31000篇
  2014年   44210篇
  2013年   66717篇
  2012年   90286篇
  2011年   95453篇
  2010年   56368篇
  2009年   53512篇
  2008年   89947篇
  2007年   96161篇
  2006年   97453篇
  2005年   94215篇
  2004年   90818篇
  2003年   87509篇
  2002年   86054篇
  2001年   149464篇
  2000年   154809篇
  1999年   130583篇
  1998年   36578篇
  1997年   32962篇
  1996年   32725篇
  1995年   31354篇
  1994年   29318篇
  1993年   27401篇
  1992年   104246篇
  1991年   100546篇
  1990年   97421篇
  1989年   94077篇
  1988年   87036篇
  1987年   85353篇
  1986年   80960篇
  1985年   77131篇
  1984年   57739篇
  1983年   49119篇
  1982年   29133篇
  1981年   25775篇
  1979年   53773篇
  1978年   37330篇
  1977年   32089篇
  1976年   29451篇
  1975年   31707篇
  1974年   38614篇
  1973年   36723篇
  1972年   34575篇
  1971年   32133篇
  1970年   30167篇
  1969年   28304篇
  1968年   25597篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.

Researchers have highlighted numerous sociocultural factors that have been shown to underpin human appearance enhancement practices, including the influence of peers, family, the media, and sexual objectification. Fewer scholars have approached appearance enhancement from an evolutionary perspective or considered how sociocultural factors interact with evolved psychology to produce appearance enhancement behavior. Following others, we argue that evidence from the field of evolutionary psychology can complement existing sociocultural models by yielding unique insight into the historical and cross-cultural ubiquity of competition over aspects of physical appearance to embody what is desired by potential mates. An evolutionary lens can help to make sense of reliable sex and individual differences that impact appearance enhancement, as well as the context-dependent nature of putative adaptations that function to increase physical attractiveness. In the current review, appearance enhancement is described as a self-promotion strategy used to enhance reproductive success by rendering oneself more attractive than rivals to mates, thereby increasing one’s mate value. The varied ways in which humans enhance their appearance are described, as well as the divergent tactics used by women and men to augment their appearance, which correspond to the preferences of opposite-sex mates in a heterosexual context. Evolutionarily relevant individual differences and contextual factors that vary predictably with appearance enhancement behavior are also discussed. The complementarity of sociocultural and evolutionary perspectives is emphasized and recommended avenues for future interdisciplinary research are provided for scholars interested in studying appearance enhancement behavior.

  相似文献   
102.
BackgroundSecond-hand smoking or environmental tobacco smoke is a critical health risk. Children are the most vulnerable to second-hand smoking because of their small bronchial ducts, less developed immunity, and low-physical activity.ObjectivesThe purpose of this study was to ascertain the effects of second-hand smoking on lung functions in athlete and non-athlete school-aged children.MethodsThis observational study included forty-six school-aged children, their age was 8–15 years, assigned to three groups; 2 study groups and 1 control group (n=15). The study groups comprised of 16 football players, and of 15 cyclists. Lung functions were evaluated recording forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow using digital spirometer.ResultsAll measures were recorded in definite values and the children were also classified into second-hand smoking (SH), or non-exposed to tobacco smoking (NE). The findings presented a significant increase (p<0.05) of the study groups in forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow solely for the non-exposed children. However, there were non-significant differences between the cyclists and football players or between the passive smoking children and non-exposed children in any of the two study groups (p>0.05).ConclusionThe outcomes of this study suggest beneficial influences of the sports activity on the lung functions, without different influences of the cyclists and football players on the lung functions.  相似文献   
103.
The Yakima Valley Farm Workers Clinic (YVFWC) is one of the largest community health centers in the country with clinics throughout south-central Washington and northern Oregon. Its dental program consists of 14 dental clinics providing general and specialty services to the low-income populations it serves. Modeling itself after the YVFWC medical managed care program; the Dental program recently added value-based metrics to its dental practice after Oregon offered a value-based dental reimbursement plan in 2019. This is the first-step YVFWC's dental program that has taken to prepare for value-based reimbursement and transform its dental practice in order to reduce the disease burden in its patient population. The purpose of this article is to describe the processes YVFWC undertook to prepare itself for the new reimbursement model, which included the development of metrics, a metric validation process, a clinical dashboard, and a method for improving metrics. It also outlines its medical/dental integration improvement brought about by embedding hygienists into the medical primary care teams.  相似文献   
104.
105.
As millions of people turn to social media for health information, better understanding the factors that guide health-related judgments and perceptions in this context is imperative. We report on two Web experiments (n > 400 total) examining the power of society’s widespread weight bias and related stereotypes to influence nutrition judgments in social media spaces. In Experiment 1, meals were judged as lower in nutritional quality when the person who recommended them (the source) was depicted as obese rather than of normal weight, an effect mediated by stereotypic beliefs about the source as a generally unhealthy person. Experiment 2 replicated this effect, which—notably—remained significant when controlling for objective nutritional information (calories and fat content). Results highlight spillover effects of weight bias that extend beyond person perception to color impressions of objects (here, food) that are associated with stigmatized attributes. Implications for everyday nutrition judgments and public health are considered.  相似文献   
106.
107.
108.
Red cell exchange (RCE) is a common procedure in adults with sickle cell disease (SCD). Implantable dual lumen Vortex (DLV) ports can be used for RCE in patients with poor peripheral venous access. We performed a retrospective cohort study of RCE procedures performed in adults with SCD. The main objective of the study was to compare the inlet speed, duration of procedures and rate of complications performed through DLV ports to those performed through temporary central venous and peripheral catheters. Twenty‐nine adults with SCD underwent a total of 318 RCE procedures. Twenty adults had DLV ports placed and 218 procedures were performed using DLV ports. Mean length of follow‐up after DLV port placement was 397 ± 263 days. Six DLV ports were removed due to infection and 1 for malfunction after a mean of 171 ± 120 days. Compared to temporary central venous and peripheral catheters, DLV port procedures had a greater rate of procedural complications, a longer duration, and a lower inlet speed (all P < 0.01). When accounting for the maximum allowable inlet speed to avoid citrate toxicity, 40% of DLV port procedures were greater than 10% below maximum speed, compared to 7 and 14% of procedures performed through temporary central venous and peripheral catheters (P < 0.0001). In conclusion, DLV ports can be used for RCE in adults with SCD, albeit with more procedural complications and longer duration. The smaller internal diameter and longer catheter of DLV ports compared to temporary central venous catheters likely accounts for the differences noted. J. Clin. Apheresis 30:353–358, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   
109.
110.
The catechol-O-methyltransferase (COMT) enzyme is a major determinant of prefrontal dopamine levels. The Val158Met polymorphism affects COMT enzymatic activity and has been associated with variation in executive function and affective processing. This study investigated the effect of COMT genotype on the flexible modulation of the balance between processing self-generated and processing stimulus-oriented information, in the presence or absence of affective distractors. Analyses included 124 healthy adult participants, who were also assessed on standard working memory (WM) tasks. Relative to Val carriers, Met homozygotes made fewer errors when selecting and manipulating self-generated thoughts. This effect was partly accounted for by an association between COMT genotype and visuospatial WM performance. We also observed a complex interaction between the influence of affective distractors, COMT genotype and sex on task accuracy: male, but not female, participants showed a sensitivity to the affective distractors that was dependent on COMT genotype. This was not accounted for by WM performance. This study provides novel evidence of the role of dopaminergic genetic variation on the ability to select and manipulate self-generated thoughts. The results also suggest sexually dimorphic effects of COMT genotype on the influence of affective distractors on executive function.  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