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   13369篇
  免费   907篇
  国内免费   26篇
耳鼻咽喉   83篇
儿科学   441篇
妇产科学   284篇
基础医学   1594篇
口腔科学   170篇
临床医学   1486篇
内科学   2343篇
皮肤病学   154篇
神经病学   1708篇
特种医学   614篇
外科学   2195篇
综合类   144篇
一般理论   22篇
预防医学   1275篇
眼科学   119篇
药学   928篇
中国医学   28篇
肿瘤学   714篇
  2023年   71篇
  2022年   106篇
  2021年   279篇
  2020年   176篇
  2019年   294篇
  2018年   334篇
  2017年   244篇
  2016年   276篇
  2015年   276篇
  2014年   466篇
  2013年   643篇
  2012年   983篇
  2011年   1058篇
  2010年   565篇
  2009年   529篇
  2008年   898篇
  2007年   855篇
  2006年   874篇
  2005年   917篇
  2004年   834篇
  2003年   782篇
  2002年   729篇
  2001年   152篇
  2000年   123篇
  1999年   129篇
  1998年   156篇
  1997年   119篇
  1996年   113篇
  1995年   107篇
  1994年   83篇
  1993年   61篇
  1992年   89篇
  1991年   66篇
  1990年   54篇
  1989年   63篇
  1988年   70篇
  1987年   64篇
  1986年   50篇
  1985年   44篇
  1984年   52篇
  1983年   59篇
  1982年   53篇
  1981年   38篇
  1980年   54篇
  1979年   33篇
  1978年   32篇
  1977年   25篇
  1976年   25篇
  1975年   18篇
  1971年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
In the present study, the requirements and characteristics forthe production of IL-13 by human T cells, T cell clones andB cells were determined and compared with those of IL-4. IL-13was produced by human CD4+ and CD8+ T lymphocyte subsets isolatedfrom peripheral blood mononuclear cells and by CD4+ and CD8+T cell clones. CD4+ T cell clones belonging to Th0, Th1-likeand Th2-like subsets produced IL-13 following antigen-specificor polyclonal activation. In addition, EBV-transformed B celllines expressed IL-13 mRNA and produced small amounts of IL-13protein. Expression of IL-13 mRNA and production of IL-13 proteinby peripheral blood T cells and T cell clones was induced rapidlyand was relatively long lasting, whereas IL-4 production bythese cells was transient In addition, IL-13 mRNA expressionwas induced by modes of activation that failed to induce IL-4mRNA expression. IL-13 shares many biological activities withIL-4 which Is compatible with the notion that the IL-13 andIL-4 receptors share a common component required for signaltransduction. However, IL-13 lacks the T cell-activating propertiesof IL-4. Here we have shown that this is related to the factthat T cells fall to bind radiolabeled IL-13 and do not expressthe IL-13-speclflc receptor component Taken together, theseresults indicate that the differences In expression and biologicalactivities of IL-4 and IL-13 on T cells may have consequencesfor the relative roles of these cytokines In the immune response.  相似文献   
53.
Inhibition of return (IOR) refers to an increase in time to react to a target in a previously attended location. Children with spina bifida meningomyelocele (SBM) and hydrocephalus have congenital dysmorphology of the midbrain, a brain region associated with the control of covert orienting in general and with IOR in particular. The authors studied exogenously cued covert orienting in 8- to 19-year-old children and adolescents (84 with SBM and 37 age-matched, typically developing controls). The exogenous cue was a luminance change in a peripheral box that was 50% valid for the upcoming target location. Compared with controls, children with SBM showed attenuated IOR in the vertical plane, a deficit that was associated with midbrain dysmorphology in the form of tectal beaking but not with posterior brain volume loss. The data add to the emerging evidence for SBM deficits in attentional orienting to salient information.  相似文献   
54.
55.
Data are presented on the family distribution of nearsightedness, including the frequency of the disorder in the children of two myopes. The previous literature is reviewed, embracing several quantitative family or population studies in addition to extensive pedigree material. It is concluded that there is substantial evidence that recessive inheritance is the principal mechanism of transmission, and that most instances of myopia probably fall into that category.  相似文献   
56.
We measured brain activity using magnetoencephalography in five participants during ongoing tasks that included prospective memory, retrospective memory, and oddball trials. Sources were identified in the hippocampal formation and posterior parietal and frontal lobes. Posterior parietal cortex activation had an earlier onset in the prospective memory condition than retrospective memory or oddball conditions, a higher level of theta activity in the retrospective condition, and higher levels of upper alpha in the prospective and oddball conditions. Activation of the hippocampal formation had a longer duration in the retrospective memory and prospective memory conditions than the oddball condition, but prominent alpha and theta band activity was present in all three conditions. We interpret the early (87 ms) onset of activity in parietal cortex as evidence for an initial noticing of appropriate conditions for a PM response. Hippocampal activity may reflect a subsequent memory search for the intended action.  相似文献   
57.
Periodontal status was studied at the mesiobuccal, midbuccal and distobuccal aspects of contralateral pairs of canines in 22 postorthodontic patients aged 30 to 51 years with a mean time of 26.4 years (SD, 5.6) out of active treatment. The pretreatment models showed one canine erupting severely to the labial ("ectopic") with a contralateral canine in good arch alignment (control). None of the patients experienced relapse of the "ectopic" canine in a labial direction, and none had missing teeth, malalignment, overhanging restorations or open tooth contacts adjacent to the canines evaluated. Periodontal parameters were examined using a Michigan #0 probe with Williams markings. A nonstandardized light force was used and the measurements were rounded to the nearest millimeter. The results demonstrated statistically significant differences between the canines in probing attachment and bone levels (mean, 0.75; SD, 0.92; P less than 0.01) and width of attached gingiva (mean, 0.50; SD, 1.07; p less than 0.05) at the midbuccal aspects. The reason for these differences could only be speculated upon.  相似文献   
58.
Advances in Health Sciences Education - Background: Despite being a mandated, foundational value in healthcare, research on compassion remains limited. Studying the individual, patient, clinical,...  相似文献   
59.
Suboptimal understanding of concepts related to hygiene by the general public, clinicians and researchers is a persistent problem in health and medicine. Although hygiene is necessary to slow or prevent deadly pandemics of infectious disease such as coronavirus disease 2019 (COVID-19), hygiene can have unwanted effects. In particular, some aspects of hygiene cause a loss of biodiversity from the human body, characterized by the almost complete removal of intestinal worms (helminths) and protists. Research spanning more than half a century documents that this loss of biodiversity results in an increased propensity for autoimmune disease, allergic disorders, probably neuropsychiatric problems and adverse reactions to infectious agents. The differences in immune function between communities with and communities without helminths have become so pronounced that the reduced lethality of severe acute respiratory syndrome coronavirus 2 in low-income countries compared to high-income countries was predicted early in the COVID-19 pandemic. This prediction, based on the maladaptive immune responses observed in many cases of COVID-19 in high-income countries, is now supported by emerging data from low-income countries. Herein, hygiene is subdivided into components involving personal choice versus components instituted by community wide systems such as sewage treatment facilities and water treatment plants. The different effects of personal hygiene and systems hygiene are described, and appropriate measures to alleviate the adverse effects of hygiene without losing the benefits of hygiene are discussed. Finally, text boxes are provided to function as stand-alone, public-domain handouts with the goal of informing the public about hygiene and suggesting solutions for biomedical researchers and policy makers.Lay Summary: Hygiene related to sewer systems and other technology can have adverse effects on immune function, and is distinct from personal hygiene practices such as hand washing and social distancing. Dealing with the drawbacks of hygiene must be undertaken without compromising the protection from infectious disease imposed by hygiene.  相似文献   
60.
Medicine, Health Care and Philosophy - Biomedical innovations are making possible the enhancement of human capabilities. There are two philosophical stances on the role that medicine should play in...  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