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   5283篇
  免费   323篇
  国内免费   24篇
耳鼻咽喉   77篇
儿科学   137篇
妇产科学   82篇
基础医学   667篇
口腔科学   576篇
临床医学   408篇
内科学   1166篇
皮肤病学   104篇
神经病学   382篇
特种医学   120篇
外科学   591篇
综合类   22篇
预防医学   614篇
眼科学   90篇
药学   373篇
中国医学   31篇
肿瘤学   190篇
  2023年   54篇
  2022年   160篇
  2021年   238篇
  2020年   171篇
  2019年   189篇
  2018年   230篇
  2017年   154篇
  2016年   157篇
  2015年   217篇
  2014年   293篇
  2013年   285篇
  2012年   428篇
  2011年   520篇
  2010年   277篇
  2009年   169篇
  2008年   319篇
  2007年   320篇
  2006年   226篇
  2005年   243篇
  2004年   167篇
  2003年   133篇
  2002年   131篇
  2001年   85篇
  2000年   81篇
  1999年   63篇
  1998年   17篇
  1997年   13篇
  1996年   27篇
  1995年   12篇
  1994年   13篇
  1993年   10篇
  1992年   37篇
  1991年   31篇
  1990年   18篇
  1989年   16篇
  1988年   13篇
  1987年   8篇
  1986年   12篇
  1985年   17篇
  1984年   9篇
  1983年   11篇
  1982年   5篇
  1979年   4篇
  1978年   4篇
  1977年   4篇
  1976年   5篇
  1971年   5篇
  1969年   4篇
  1968年   3篇
  1967年   4篇
排序方式: 共有5630条查询结果,搜索用时 15 毫秒
31.
Increasing epidemiological evidence suggests that optimal diet quality helps to improve preservation of lung function and to reduce chronic obstructive pulmonary disease (COPD) risk, but no study has investigated the association of food insecurity (FI) and lung health in the general population. Using data from a representative sample of US adults who participated in the National Health and Nutrition Examination Survey (NHANES) 2007–2012 cycles, we investigated the association between FI with lung function and spirometrically defined COPD in 12,469 individuals aged ≥ 18 years of age. FI (high vs. low) was defined using the US Department of Agriculture’s Food Security Scale). Population-weighted adjusted regression models were used to investigate associations between FI, and forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), their ratio, and spirometrically defined restriction (FVC below the lower limit of normal) and airflow obstruction (COPD). The prevalence of household FI was 13.2%. High household FI was associated with lower FVC (adjusted β-coefficient −70.9 mL, 95% CI −116.6, −25.3), and with higher odds (OR) of spirometric restriction (1.02, 95% CI 1.00, 1.03). Stratified analyses showed similar effect sizes within specific ethnic groups. High FI was associated with worse lung health in a nationally representative sample of adults in the US.  相似文献   
32.
The association between obesity and vitamin A has been studied. Some studies point to the anti-obesity activity related to this vitamin, carotenoids with provitamin A activity, and carotenoid conversion products. This performance has been evaluated in respect of adipogenesis, metabolic activity, oxidation processes, secretory function, and oxidative stress modulation, showing a new property attributed to vitamin A in preventing and treating obesity. However, vitamin A and its precursors are highly sensitive and easily degraded when subjected to heat, the presence of light, and oxygen, in addition to losses related to the processes of digestion and absorption. In this context, encapsulation presents itself as an alternative capable of increasing vitamin A’s stability in the face of unfavorable conditions in the environment, which can reduce its functionality. Considering that vitamin A’s status shows a strong correlation with obesity and is an innovative theme, this article addresses the associations between vitamin A’s consumption and its precursors, encapsulated or not, and its physiological effects on obesity. The present narrative review points out those recent studies that demonstrate that vitamin A and its encapsulated precursors have the most preserved functionality, which guarantees better effects on obesity therapy.  相似文献   
33.
Lasers in Medical Science - The aim of the present study was to investigate the effects of photobiomodulation (PBM) therapy on the expression of heat shock protein 70 (HSP70) and tissue repair in...  相似文献   
34.
Lasers in Medical Science - Physical activity raises body temperature. However, the literature does not contain studies about whether the employment of hotobiomodulation (PMB) could significantly...  相似文献   
35.
Background/PurposeThe aim of the study was to evaluate the postoperative quality of life (QoL) of patients who underwent minimally invasive repair of pectus excavatum (MIRPE) with a newly designed bar and bar stabilizers.MethodsWe conducted a prospective randomized study in which patients were operated either with standard perpendicular stabilizers (control group) or with the newly designed oblique stabilizers (intervention group). All patients were evaluated 6 months after the operation with the Pectus Excavatum Evaluation Questionnaire (PEEQ).ResultsThere were 16 patients in the control group and 14 in the intervention group. Mean age was 17 (SD: 3.3, range 14–27) years. There were no demographic differences between groups. Two patients in the control group and one in the intervention group were repaired with two bars instead of one. There was one reoperation in each group. There was a significant difference between the pre- and postoperative scores, in both groups, in the patient body image domain (control group: 9.5 to 3; p < 0.01; intervention group 10 to 3; p < 0.01), as well as in the psychosocial domain (control group: 13.5 to 24, p < 0.01; intervention group: 15 to 24, p < 0.01). With regards to the patients' perception of physical difficulties before and after MIRPE, the difference between pre- and postoperative scores was greater in the intervention group (8 to 12, p < 0.01) than in the control group (10 to 11, p = 0.04). The mean length of stay was 4.5 and 5 days in the intervention group and the control group, respectively.ConclusionOur study showed that patients who underwent MIRPE with the newly designed bars and stabilizers had non-inferior outcomes than patients reported in the literature who underwent MIRPE with standard bars and stabilizers. We found slightly better outcomes in patients in the intervention group compared to the control group, but larger studies will be needed to confirm if those differences are statistically significant.Level of evidenceII  相似文献   
36.
37.
38.
Vaccine adjuvants are compounds that enhance/prolong the immune response to a co-administered antigen. Saponins have been widely used as adjuvants for many years in several vaccines – especially for intracellular pathogens – including the recent and somewhat revolutionary malaria and shingles vaccines. In view of the immunoadjuvant potential of Q. brasiliensis saponins, the present study aimed to characterize the QB-80 saponin-rich fraction and a nanoadjuvant prepared with QB-80 and lipids (IMXQB-80). In addition, the performance of such adjuvants was examined in experimental inactivated vaccines against Zika virus (ZIKV). Analysis of QB-80 by DI-ESI-ToF by negative ion electrospray revealed over 29 saponins that could be assigned to known structures existing in their congener Q. saponaria, including the well-studied QS-21 and QS-7. The QB-80 saponins were a micrOTOF able to self-assembly with lipids in ISCOM-like nanoparticles with diameters of approximately 43 nm, here named IMXQB-80. Toxicity assays revealed that QB-80 saponins did present some haemolytical and cytotoxic potentials; however, these were abrogated in IMXQB-80 nanoparticles. Regarding the adjuvant activity, QB-80 and IMXQB-80 significantly enhanced serum levels of anti-Zika virus IgG and subtypes (IgG1, IgG2b, IgG2c) as well as neutralized antibodies when compared to an unadjuvanted vaccine. Furthermore, the nanoadjuvant IMXQB-80 was as effective as QB-80 in stimulating immune responses, yet requiring fourfold less saponins to induce the equivalent stimuli, and with less toxicity. These findings reveal that the saponin fraction QB-80, and particularly the IMXQB-80 nanoadjuvant, are safe and capable of potentializing immune responses when used as adjuvants in experimental ZIKV vaccines.  相似文献   
39.
In order to better understand the natural history of chronic functional constipation, a questionnaire was applied to 163 children and infants, before beginning standardized treatment. Median age (range) at start was 3 mo(0-108 mo) but age at arrival at the Pediatric Gastroenterology Unit was 53 mo(2-146 mo). In 62.4% of the cases symptoms began before or up to 3 mo after cow's milk introduction and rarely around (-/+ 6 mo) toilet training. Possible complications appeared progressively, often at preschool or school age or as the first noticeable manifestation: recurrent abdominal pain (61.1%), fecal soiling (45.4%), fecal blood (35%), enuresis (23.3%), vomiting (19%), urinary infection (17.9%), urinary retention (8.6%). Abdominal distension was rarely detected on physical examination and was usually discrete. In conclusion, children attended in Botucatu begin their constipation at an early age, frequently associated with weaning,and important complications may ensue along years. This evolution should be avoided by prevention and early treatment of constipation.  相似文献   
40.
In developing countries, lead-acid battery factories are one of the heaviest consumers of lead. Due to lead's toxicological properties and prevalent working conditions in such factories, workers are subject to high exposure and health risk. This study discusses results obtained by lead exposure assessment of workers from a Rio de Janeiro battery factory, in light of Brazilian legislation and recent scientific data. Evaluation methods used were environmental (personal air sampling) and biological (determination of lead in blood, Pb-B) monitoring, showing a high personal exposure both in air (>0.1 mg/m3) and blood (55% of Pb-B >25 microg/dl). These results confirmed the inefficiency of current control measures, with a possible 46% of workers presenting a Pb-B range of 25-60 microg/dl in risk areas. Recent data suggest that Pb-B levels above 25 microg/dl are related to subclinical alterations in human body that should be investigated during clinical examination. Finally, we propose a strategy based on environmental and biological monitoring to prevent both clinical and subclinical effects.  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