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   5517篇
  免费   387篇
  国内免费   31篇
耳鼻咽喉   58篇
儿科学   269篇
妇产科学   119篇
基础医学   663篇
口腔科学   170篇
临床医学   560篇
内科学   1254篇
皮肤病学   69篇
神经病学   452篇
特种医学   309篇
外国民族医学   1篇
外科学   557篇
综合类   63篇
一般理论   2篇
预防医学   456篇
眼科学   71篇
药学   467篇
  1篇
中国医学   8篇
肿瘤学   386篇
  2023年   25篇
  2022年   82篇
  2021年   124篇
  2020年   106篇
  2019年   147篇
  2018年   142篇
  2017年   110篇
  2016年   135篇
  2015年   144篇
  2014年   192篇
  2013年   251篇
  2012年   349篇
  2011年   329篇
  2010年   205篇
  2009年   229篇
  2008年   316篇
  2007年   283篇
  2006年   255篇
  2005年   256篇
  2004年   245篇
  2003年   191篇
  2002年   197篇
  2001年   91篇
  2000年   75篇
  1999年   90篇
  1998年   130篇
  1997年   118篇
  1996年   109篇
  1995年   76篇
  1994年   80篇
  1993年   72篇
  1992年   58篇
  1991年   53篇
  1990年   48篇
  1989年   67篇
  1988年   53篇
  1987年   60篇
  1986年   32篇
  1985年   52篇
  1984年   42篇
  1983年   28篇
  1982年   27篇
  1981年   33篇
  1980年   17篇
  1979年   24篇
  1978年   16篇
  1977年   15篇
  1976年   21篇
  1975年   19篇
  1972年   12篇
排序方式: 共有5935条查询结果,搜索用时 31 毫秒
101.
In Huntington disease (HD), immune cells are activated before symptoms arise; however, it is unclear how the expression of mutant huntingtin (htt) compromises the normal functions of immune cells. Here we report that primary microglia from early postnatal HD mice were profoundly impaired in their migration to chemotactic stimuli, and expression of a mutant htt fragment in microglial cell lines was sufficient to reproduce these deficits. Microglia expressing mutant htt had a retarded response to a laser-induced brain injury in vivo. Leukocyte recruitment was defective upon induction of peritonitis in HD mice at early disease stages and was normalized upon genetic deletion of mutant htt in immune cells. Migration was also strongly impaired in peripheral immune cells from pre-manifest human HD patients. Defective actin remodeling in immune cells expressing mutant htt likely contributed to their migration deficit. Our results suggest that these functional changes may contribute to immune dysfunction and neurodegeneration in HD, and may have implications for other polyglutamine expansion diseases in which mutant proteins are ubiquitously expressed.  相似文献   
102.
103.
The role of serology in the setting of PCR-based diagnosis of acute respiratory infections (ARIs) is unclear. We found that acute- and convalescent-phase paired-sample serologic testing increased the diagnostic yield of naso/oropharyngeal swabs for influenza virus, respiratory syncytial virus (RSV), human metapneumovirus, adenovirus, and parainfluenza viruses beyond PCR by 0.4% to 10.7%. Although still limited for clinical use, serology, along with PCR, can maximize etiologic diagnosis in epidemiologic studies.  相似文献   
104.
We examined the impact of acute noise stress on the feedback-related negativity (FRN) and whether this effect depended on stressor predictability. Participants performed a gambling task in a silence and a noise condition with either predictable or unpredictable noise. FRN amplitude was measured in three ways, either neglecting (mean amplitude) or correcting for overlap with other components (base-to-peak; mean amplitude minus average mean amplitude of surrounding peaks). Notably, results differed between measures. Valence and magnitude both affected the FRN. These effects were additive on the mean amplitude and base-to-peak measures, but interactive on the mean amplitude corrected for both peaks measure. Acute noise stress specifically modulated valence and magnitude effects on the FRN, although evidence differed between measures as to whether valence and/or magnitude were processed differently. These findings indicate that acute stress impairs cognitive control by the anterior cingulate cortex. Stressor predictability added little to the explanation of effects.  相似文献   
105.
The aim of this study was to evaluate the usefulness of spectrometrically measured colour parameters of teeth for age estimation in living adults. A total of 329 teeth were selected (162 upper central incisors and 167 upper canines) from 52 men and 50 women aged between 20 and 86 years. Colour measurements were performed in vivo on the vestibular surface of the teeth using a portable contact Spectro-color device. Colorimetric variables (L*, a*, b*), chromaticity coordinates (x, y, z), and indexes of whiteness (WIC, Z%, WI) and yellowness (YI) were calculated. The accuracy of colour values to estimate the age was determined by Receiver Operating Characteristic analysis. A more powerful age discrimination was obtained with upper incisors than with upper canines. Areas under the ROC curve ranged from 0.7 to 0.8 for all dental colour parameters measured in upper central incisors except for the variables L* and Z%, with sensitivity values ranging from 56% to 93% and specificity values from 38% to 92%. We conclude that spectrophotometric dental colour measurement may be an objective and useful tool to estimate age and meets medical ethical standards for application in living adults. However, further research is needed to study the effect of ethnicity and other factors on tooth colour.  相似文献   
106.
In tumours, hypoxia—a condition in which the demand for oxygen is higher than its availability—is well known to be associated with reduced sensitivity to radiotherapy and chemotherapy, and with immunosuppression. The consequences of hypoxia on tumour biology and patient outcomes have therefore led to the investigation of strategies that can alleviate hypoxia in cancer cells, with the aim of sensitising cells to treatments. An alternative therapeutic approach involves the design of prodrugs that are activated by hypoxic cells. Increasing evidence indicates that hypoxia is not just clinically significant in adult cancers but also in paediatric cancers. We evaluate relevant methods to assess the levels and extent of hypoxia in childhood cancers, including novel imaging strategies such as oxygen-enhanced magnetic resonance imaging (MRI). Preclinical and clinical evidence largely supports the use of hypoxia-targeting drugs in children, and we describe the critical need to identify robust predictive biomarkers for the use of such drugs in future paediatric clinical trials. Ultimately, a more personalised approach to treatment that includes targeting hypoxic tumour cells might improve outcomes in subgroups of paediatric cancer patients.Subject terms: Tumour biomarkers, Paediatric cancer, Cancer microenvironment, Cancer therapy  相似文献   
107.
ObjectiveTo determine whether adolescents with polycystic ovary syndrome (PCOS) are more depressed than adolescent girls in the community and to examine factors associated with depression.DesignAn observational study comparing clinical and community samples.SettingTwo specialist reproductive endocrine clinics in Auckland, New Zealand.Participants102 girls aged 14-19 presenting for clinical assessment, fulfilling the Rotterdam consensus for PCOS. The comparison group was 1349 girls from a school-based survey of New Zealand youth.InterventionsClinically significant depression was identified by the long and short form Reynolds Adolescent Depression Scale. BMI, androgen levels, oral contraceptive use, objective symptom severity, age, ethnicity, and socioeconomic grouping were recorded.Main Outcome MeasuresClinically significant depression in the PCOS and community samples. Potential determinants of depression.ResultsClinically significant depression in adolescent girls with PCOS was not increased compared with the community sample (OR 1.3; 95%CI 0.7-2.7, P = .42). Within the PCOS cohort, depression was correlated with increased BMI (P = .01) and possibly acne (P = .08).ConclusionsLean adolescent girls with PCOS did not have more clinically significant depression than girls in the community. Within the PCOS cohort, however, there was a clear association between higher depression scores and elevated BMI. There is a potentially important interaction between obesity and depression in PCOS.  相似文献   
108.
109.
The importance of self-awareness in counselling education is widely recognized; however, strengthening this vital aspect is often left to educators’ discretion. The author addresses this deficiency by first exploring four theoretical constructs: mindfulness, emotional regulation, death anxiety, and relationship dynamics. Then, she outlines a practical learning activity on the topic of death. The main exercise involves a guided meditation in which students imagine both a worst-case and best-case scenario of their own death, while practicing mindfulness, followed by a debriefing period and a written self-reflection. This activity can be used by educators to promote greater self-awareness in master’s level counselling students.  相似文献   
110.
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