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   2688篇
  免费   349篇
  国内免费   231篇
耳鼻咽喉   21篇
儿科学   27篇
妇产科学   7篇
基础医学   312篇
口腔科学   35篇
临床医学   125篇
内科学   231篇
皮肤病学   19篇
神经病学   92篇
特种医学   43篇
外科学   112篇
综合类   366篇
预防医学   248篇
眼科学   35篇
药学   560篇
中国医学   1009篇
肿瘤学   26篇
  2024年   23篇
  2023年   69篇
  2022年   122篇
  2021年   136篇
  2020年   96篇
  2019年   124篇
  2018年   93篇
  2017年   130篇
  2016年   129篇
  2015年   127篇
  2014年   176篇
  2013年   229篇
  2012年   222篇
  2011年   208篇
  2010年   157篇
  2009年   112篇
  2008年   126篇
  2007年   126篇
  2006年   115篇
  2005年   92篇
  2004年   68篇
  2003年   71篇
  2002年   62篇
  2001年   60篇
  2000年   37篇
  1999年   31篇
  1998年   34篇
  1997年   31篇
  1996年   15篇
  1995年   12篇
  1994年   22篇
  1993年   16篇
  1992年   28篇
  1991年   13篇
  1990年   17篇
  1989年   18篇
  1988年   11篇
  1987年   11篇
  1986年   6篇
  1985年   13篇
  1984年   15篇
  1983年   16篇
  1982年   12篇
  1981年   6篇
  1980年   8篇
  1979年   4篇
  1978年   4篇
  1977年   3篇
  1976年   4篇
  1973年   3篇
排序方式: 共有3268条查询结果,搜索用时 15 毫秒
71.
《Vaccine》2022,40(48):6931-6938
BackgroundInfluenza increases stillbirth risk, morbidity and mortality in pregnant women. Vaccination protects pregnant women against severe disease and indirectly protects their infants, but coverage among pregnant women remains low worldwide. We aimed to describe knowledge, attitudes, and practices (KAP) regarding seasonal influenza vaccination among postpartum women and prenatal care physicians in Costa Rica.MethodsWe conducted cross-sectional KAP surveys to women one to three days after childbirth at Costa Rican Social Security Fund maternity hospitals, and obstetricians and general practitioners who provided prenatal care in 2017. Principal components analysis, multiple imputation, and logistic regression were used to examine associations between influenza vaccination and demographics, prenatal care, and sources of information—separately for postpartum women and physicians. We also held two focus groups of six healthcare workers each to further describe vaccination KAP.ResultsWe surveyed 642 postpartum women and 146 physicians in maternity hospitals in five Costa Rican provinces of whom 85.5 % (95 % CI: 82.6 %-88.0 %) and 57.9 % (95 % CI: 49.6 %-65.7 %) were vaccinated for influenza, respectively. Factors associated with influenza vaccination for postpartum women included tetanus vaccination (aOR: 3.62, 95 % CI: 1.89–6.92); received vaccination recommendations from clinicians during prenatal check-ups (aOR: 3.39, 95 % CI: 2.06–5.59); had other children in household vaccinated for influenza (aOR: 2.25, 95 % CI: 1.08–4.68); and secondary/university education (aOR: 0.15–0.31) with no formal education as reference. For postpartum women, reasons for vaccination were perceived benefits for mother and infant, whereas not being offered vaccines was most cited for non-vaccination. Most prenatal care physicians recommended influenza vaccines during prenatal check-ups but believed vaccination causes flu-like symptoms.ConclusionVaccination campaigns and provisions of free vaccines effectively increased knowledge and coverage among women in Costa Rica. To improve access, women should be offered vaccines during prenatal care appointments. Educating healthcare workers about vaccine benefits for themselves and patients is needed to mitigate safety concerns.  相似文献   
72.
Background: Growing evidence indicates that toxicity of fine particulate matter ≤ 2.5 μm in diameter (PM2.5) differs by chemical component. Exposure to components may differ by population.Objectives: We investigated whether exposures to PM2.5 components differ by race/ethnicity, age, and socioeconomic status (SES).Methods: Long-term exposures (2000 through 2006) were estimated for 215 U.S. census tracts for PM2.5 and for 14 PM2.5 components. Population-weighted exposures were combined to generate overall estimated exposures by race/ethnicity, education, poverty status, employment, age, and earnings. We compared population characteristics for tracts with and without PM2.5 component monitors.Results: Larger disparities in estimated exposures were observed for components than for PM2.5 total mass. For race/ethnicity, whites generally had the lowest exposures. Non-Hispanic blacks had higher exposures than did whites for 13 of the 14 components. Hispanics generally had the highest exposures (e.g., 152% higher than whites for chlorine, 94% higher for aluminum). Young persons (0–19 years of age) had levels as high as or higher than other ages for all exposures except sulfate. Persons with lower SES had higher estimated exposures, with some exceptions. For example, a 10% increase in the proportion unemployed was associated with a 20.0% increase in vanadium and an 18.3% increase in elemental carbon. Census tracts with monitors had more non-Hispanic blacks, lower education and earnings, and higher unemployment and poverty than did tracts without monitors.Conclusions: Exposures to PM2.5 components differed by race/ethnicity, age, and SES. If some components are more toxic than others, certain populations are likely to suffer higher health burdens. Demographics differed between populations covered and not covered by monitors.  相似文献   
73.
74.
Home literacy environment (HLE) is one of most important modifiable risk factors to dyslexia. With the development in technology, we include the electronic devices usage at home, such as computers and televisions, to the definition of HLE and investigate its impact on dyslexia based on the on-going project of Tongji's Reading Environment and Dyslexia Study. The data include 5063 children, primary school students (grade 3–grade 6), from a middle-sized city in China. We apply the principal component analysis (PCA) to reduce the large dimension of variables in HLE, and find the first three components, denoted as PC1, PC2 and PC3, can explain 95.45% of HLE information. PC1 and PC2 demonstrate strong positive association with ‘total time spending on electronic devices’ and ‘literacy-related activity’, respectively. PC3 demonstrates strong negative association with ‘restrictions on using electronic devices’. From the generalized linear model, we find that PC1 significantly increases the risk of dyslexia (OR = 1.043, 95% CI: 1.018–1.070), while PC2 significantly decreases the risk of dyslexia (OR = 0.839, 95% CI: 0.795–0.886). Therefore, reducing the total time spending on electronic devices and increasing the literacy-related activity would be the potential protective factors for dyslexic children in China.  相似文献   
75.
《Seminars in immunology》2016,28(4):384-393
Efforts to reverse the pathologic consequences of vulnerable plaques are often stymied by the complex treatment resistant pro-inflammatory environment within the plaque. This suggests that pro-atherogenic stimuli, such as LDL cholesterol and high fat diets may impart longer lived signals on (innate) immune cells that persist even after reversing the pro-atherogenic stimuli. Recently, a series of studies challenged the traditional immunological paradigm that innate immune cells cannot display memory characteristics. Epigenetic reprogramming in these myeloid cell subsets, after exposure to certain stimuli, has been shown to alter the expression of genes upon re-exposure. This phenomenon has been termed trained innate immunity or innate immune memory. The changed responses of ‘trained’ innate immune cells can confer nonspecific protection against secondary infections, suggesting that innate immune memory has likely evolved as an ancient mechanism to protect against pathogens. However, dysregulated processes of immunological imprinting mediated by trained innate immunity may also be detrimental under certain conditions as the resulting exaggerated immune responses could contribute to autoimmune and inflammatory diseases, such as atherosclerosis. Pro-atherogenic stimuli most likely cause epigenetic modifications that persist for prolonged time periods even after the initial stimulus has been removed. In this review we discuss the concept of trained innate immunity in the context of a hyperlipidemic environment and atherosclerosis. According to this idea the epigenome of myeloid (progenitor) cells is presumably modified for prolonged periods of time, which, in turn, could evoke a condition of continuous immune cell over-activation.  相似文献   
76.
77.
78.

Aims

This study aimed to investigate the relationship between the total antioxidant capacity (TAC) and Malondialdehyde (MDA) with number of metabolic syndrome (Mets) components on the personnel working in Shahroud University of Medical Sciences.

Methods

This cross-sectional study was conducted on 167 personnel aged 30–60 years old. ATP III criteria were used to diagnose patients with MetS. Oxidative stress indicators were measured. The data was analyzed via one-way ANOVA, and Pearson and Spearman correlation coefficients.

Results

The result showed that TAC had a significant positive correlation with HDL and a significant negative correlation with abdominal obesity. In addition, there was a significant positive association between the level of MDA and age, BMI, abdominal obesity, diastolic blood pressure, triglycerides, and LDL; however, it had a negative significant correlation with HDL.

Conclusions

The measurement of TAC and MDA biomarkers can increase the early diagnosis of patients at risk of developing Mets.  相似文献   
79.
摘 要 分泌性腹泻威胁着全球健康,是儿童发病和死亡的主要原因之一。肠上皮细胞腔内Cl-通道激活导致肠道液体过度分泌是肠毒素引起腹泻的主要原因。在霍乱及其他细菌肠毒素引发的腹泻中,囊性纤维化跨膜传导调节因子(cystic fibrosis transmembrane conductance regulator, CFTR)是主要的cAMP-调节Cl 通道,其主要功能是促进上皮细胞液体分泌。利用肠上皮细胞CFTR抑制药抗分泌性腹泻是一种新途径。已有的CFTR抑制药有噻唑啉酮类、甘氨酸酰肼类和喹喔啉二酮等。同时,从天然植物中提取分离的一些成分也具有CFTR抑制作用,但研究还不够深入。因此,对CFTR抑制药的研究进展进行了综述。  相似文献   
80.
目的:探究和验证黄金菊中抗炎镇痛的药效组分,比较注射用黄金菊粉针剂与口服黄金菊药效组分在抗炎镇痛上的生物等效性。方法:通过小鼠血管通透性试验、二甲苯致小鼠耳缘肿胀、醋酸扭体和热板实验,比较黄金菊药效组分对口服组和注射组抗炎镇痛的生物等效性,确定黄金菊的抗炎镇痛药效组分。结果:小鼠血管通透性实验中,阳性组的伊文思兰含量为(4.823±0.158)μg/mL,黄金菊口服组和注射用黄金菊组分别为(6.323±0.172)μg/mL和(5.959±0.134)μg/mL,两组间比较(P>0.05),其与阳性组相比(P<0.05);二甲苯致小鼠耳缘肿胀实验中,阳性组肿胀度为(0.8125±0.5489)mg,黄金菊口服组和注射用黄金菊组分别为(1.05±0.466)mg和(1.3±1.234)mg,两组间比较(P>0.05),其与阳性组相比(P<0.05);醋酸扭体实验中,阳性组扭体次数为(33.5±2.121)次,黄金菊口服组和注射用黄金菊组分别为(35.5±3.535)次和(29±1.421)次,两组间比较(P>0.05),其与阳性组相比(P<0.05);热板实验中,阳性组的痛阈提高百分率为(56.38±1.418)%,黄金菊口服组和注射用黄金菊组分别为(64.92±2.421)%和(78.85±3.682)%,两组间比较(P>0.05),其与阳性组相比(P<0.01)。结论:黄金菊的药效组分中黄芩苷、绿原酸、荭草苷和牡荆苷可以作为黄金菊的抗炎镇痛有效组分,注射用黄金菊粉针剂与口服黄金菊的药效组分中抗炎和镇痛作用上具有生物等效性。  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