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   3090篇
  免费   193篇
  国内免费   23篇
耳鼻咽喉   15篇
儿科学   71篇
妇产科学   52篇
基础医学   490篇
口腔科学   70篇
临床医学   332篇
内科学   668篇
皮肤病学   40篇
神经病学   347篇
特种医学   97篇
外科学   332篇
综合类   21篇
预防医学   235篇
眼科学   43篇
药学   193篇
中国医学   2篇
肿瘤学   298篇
  2023年   43篇
  2022年   26篇
  2021年   77篇
  2020年   70篇
  2019年   95篇
  2018年   94篇
  2017年   86篇
  2016年   88篇
  2015年   86篇
  2014年   155篇
  2013年   184篇
  2012年   234篇
  2011年   292篇
  2010年   152篇
  2009年   140篇
  2008年   252篇
  2007年   242篇
  2006年   191篇
  2005年   179篇
  2004年   131篇
  2003年   121篇
  2002年   95篇
  2001年   11篇
  2000年   13篇
  1999年   20篇
  1998年   19篇
  1997年   13篇
  1996年   17篇
  1995年   19篇
  1994年   14篇
  1993年   13篇
  1992年   12篇
  1991年   4篇
  1989年   3篇
  1988年   6篇
  1987年   11篇
  1986年   12篇
  1985年   6篇
  1984年   13篇
  1983年   7篇
  1982年   10篇
  1981年   4篇
  1979年   10篇
  1978年   3篇
  1977年   3篇
  1975年   3篇
  1972年   2篇
  1969年   2篇
  1968年   2篇
  1955年   2篇
排序方式: 共有3306条查询结果,搜索用时 31 毫秒
1.
Harinakshi Sanikini  David C. Muller  Marisa Sophiea  Sabina Rinaldi  Antonio Agudo  Eric J. Duell  Elisabete Weiderpass  Kim Overvad  Anne Tjønneland  Jytte Halkjær  Marie-Christine Boutron-Ruault  Franck Carbonnel  Iris Cervenka  Heiner Boeing  Rudolf Kaaks  Tilman Kühn  Antonia Trichopoulou  Georgia Martimianaki  Anna Karakatsani  Valeria Pala  Domenico Palli  Amalia Mattiello  Rosario Tumino  Carlotta Sacerdote  Guri Skeie  Charlotta Rylander  María-Dolores Chirlaque López  Maria-Jose Sánchez  Eva Ardanaz  Sara Regnér  Tanja Stocks  Bas Bueno-de-Mesquita  Roel C.H. Vermeulen  Dagfinn Aune  Tammy Y.N. Tong  Nathalie Kliemann  Neil Murphy  Marc Chadeau-Hyam  Marc J. Gunter  Amanda J. Cross 《International journal of cancer. Journal international du cancer》2020,146(4):929-942
Obesity has been associated with upper gastrointestinal cancers; however, there are limited prospective data on associations by subtype/subsite. Obesity can impact hormonal factors, which have been hypothesized to play a role in these cancers. We investigated anthropometric and reproductive factors in relation to esophageal and gastric cancer by subtype and subsite for 476,160 participants from the European Prospective Investigation into Cancer and Nutrition cohort. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox models. During a mean follow-up of 14 years, 220 esophageal adenocarcinomas (EA), 195 esophageal squamous cell carcinomas, 243 gastric cardia (GC) and 373 gastric noncardia (GNC) cancers were diagnosed. Body mass index (BMI) was associated with EA in men (BMI ≥30 vs. 18.5–25 kg/m2: HR = 1.94, 95% CI: 1.25–3.03) and women (HR = 2.66, 95% CI: 1.15–6.19); however, adjustment for waist-to-hip ratio (WHR) attenuated these associations. After mutual adjustment for BMI and HC, respectively, WHR and waist circumference (WC) were associated with EA in men (HR = 3.47, 95% CI: 1.99–6.06 for WHR >0.96 vs. <0.91; HR = 2.67, 95% CI: 1.52–4.72 for WC >98 vs. <90 cm) and women (HR = 4.40, 95% CI: 1.35–14.33 for WHR >0.82 vs. <0.76; HR = 5.67, 95% CI: 1.76–18.26 for WC >84 vs. <74 cm). WHR was also positively associated with GC in women, and WC was positively associated with GC in men. Inverse associations were observed between parity and EA (HR = 0.38, 95% CI: 0.14–0.99; >2 vs. 0) and age at first pregnancy and GNC (HR = 0.54, 95% CI: 0.32–0.91; >26 vs. <22 years); whereas bilateral ovariectomy was positively associated with GNC (HR = 1.87, 95% CI: 1.04–3.36). These findings support a role for hormonal pathways in upper gastrointestinal cancers.  相似文献   
2.
3.

Objectives

To investigate whether the exercise performance benefits with neck cooling in the heat are attributable to neck-specific cooling, general body cooling, a cooler site-specific thermal perception or a combination of the above.

Design

Counter-balanced crossover design.

Methods

Twelve healthy participants cycled in the heat (34 °C, 30% relative humidity), at a power output (PO) self-selected to maintain a fixed rating of perceived exertion (RPE) of 16. Each participant underwent four experimental trials: no cooling (CON), neck cooling (NEC), abdominal cooling (ABD), or neck cooling with menthol (MEN). Participants cycled for 90 min or until their workload reduced by <70% of their initial PO. Changes in PO, rectal temperature (Tre), mean skin temperature (Tsk), whole-body thermal sensation (TSwb) and thermal sensation of the neck (TSneck) were recorded throughout.

Results

The mean reduction in PO throughout exercise was similar (p = 0.431) for CON (175 ± 10 W), NEC (176 ±12 W), ABD (172 ± 13 W) and MEN (174 ± 12 W). The ΔTre at the end of exercise was similar (p = 0.874) for CON (0.83 ± 0.5 °C), NEC (0.85 ± 0.5 °C), ABD (0.82 ± 0.5 °C) and MEN (0.81 ± 0.5 °C). TSwb was cooler (p < 0.013) in MEN (125 ± 8 mm) compared to CON (146 ± 19 mm), NEC (135 ± 11 mm) and ABD (141 ± 16 mm).

Conclusions

No differences in exercise performance or thermal strain were observed in any of the cooling trials compared to the CON trial, despite significantly cooler TSwb values in the MEN and NEC trials compared to the CON trial. These findings differ from previous observations and highlight that the benefit of neck cooling may be situation dependent.  相似文献   
4.
Lasers in Medical Science - The aim of this study was to investigate the effect of red laser (660 nm) photobiomodulation (PBM) with different energies on tumor necrosis factor-alpha(TNF-α)...  相似文献   
5.
6.
Among the numerous signaling pathways involved in tumorigenesis, PI3K‐AKT‐mTOR is a key one that regulates diverse cellular functions. However, its prognostic value in esophageal carcinoma remains unclear. In our study, we examined the immunohistochemical expression of phosphorylated (p‐) AKT, mTOR, p70S6K and 4E‐BP1 along with the mutational status of PIK3CA and AKT1 genes by High Resolution Melting Analysis and Pyrosequencing in 44 esophageal carcinomas. The results were correlated with the clinicopathological characteristics of the patients in an effort to define their possible prognostic significance. Total p‐mTOR cytoplasmic expression, assessed in 10 random areas, was positively correlated with tumor stage (Kruskal–Wallis ANOVA, I/II vs III/IV, p = 0.0500). Μoreover, maximum p‐mTOR cytoplasmic immunoexpression, estimated in hot spot areas, was positively associated with tumor grade (Mann–Whitney U test, I/II vs III, p = 0.0565). Interestingly, p‐4E‐BP1 immunoreactivity was negatively correlated with tumor histological grade (Mann–Whitney U test, I/II vs III, p = 0.0427). No mutation was observed in exons 9 and 20 of PIK3CA gene and in exon 4 of AKT1 gene. In conclusion, our findings depict the presence of activated PI3K/AKT/mTOR pathway in esophageal cancer bringing forward p‐mTOR and p‐4E‐BP1 for their potential role in esophageal carcinogenesis. Additional studies are warranted to validate our findings.  相似文献   
7.
Amyotrophic lateral sclerosis (ALS) is a rare and fatal neurodegenerative disorder. Two forms are recognized, familial (FALS) that accounts for 5–10% of ALS cases, and sporadic (SALS) that accounts for the rest. Early diagnosis of ALS is important because it improves their therapeutic efficacy. Current diagnosis is based on clinical assessment and requires approximately 12 months, leading to a significant delay in drug administration. Therefore, new methods are required for the earlier diagnosis of ALS. Screening for pathogenic variants in known ALS‐associated genes is already exploited as a diagnostic tool in ALS but cannot be applied for population‐based screening. New circulating biomarkers (proteins or small molecules) are needed for initial screening, whereas specific diagnostic methods can be applied to confirm the presence of pathogenic variants in the selected population subgroup. Lipids appear as promising biomarkers for population‐based screening and for monitoring disease progression. Genetic analysis can also assist in the prediction of disease progression by analyzing disease‐modifying genes, for example, EPHA4 and CHGB. Furthermore, molecular diagnosis will aid the stratification of ALS patients for improved pharmacological approaches. Here, we discuss current and novel diagnostic strategies and how they can be applied to revolutionize the field of ALS molecular diagnosis.  相似文献   
8.
9.
Enteroviral meningitis in infants and children commonly leads to hospital admission. Diagnosing viral meningitis can be difficult clinically. We examined the usefulness of enteroviral polymerase chain reaction (PCR) testing using cerebrospinal fluid (CSF) samples on clinical practice by comparing positive enteroviral CSF PCR cases (n = 39/136) to negative controls using both clinical outcomes and laboratory parameters. A positive result correlated with a reduced admission to high dependency unit, reduced the duration of antibiotics and a shorter length of stay (P < .05). Adjusted CSF white cell count > 5/μL correlated with positive PCR (P < .05) but would have missed 32% of cases of enteroviral meningitis. Following these findings, an algorithm for the management of suspected viral meningitis has been introduced.  相似文献   
10.

Dirofilaria immitis (heartworm) is enzootic in many areas of the world and quite prevalent in southern European countries. Although dogs are the main host of the parasite, cats may also be infected, and the prevalence of feline dirofilariosis is associated with the respective prevalence of canine infection in any given area. The aim of the present study was to investigate the proportion of D. immitis infection among dogs and cats that were not under any kind of prophylactic treatment and were living in a heartworm enzootic area. In total, 180 stray animals (148 dogs and 32 cats) living in a shelter in Northern Greece were examined for heartworm infection by the Knott’s test and serology (antigen and in cats also antibody detection), and additionally echocardiography in the infected cats. Thirty-seven (25%, CI 18.7–32.5%) of the dogs and 3 (9.4%, CI 3.2–24.2%) of cats were found to be positive, by at least one of the tests applied. In 2 of the infected cats, the parasites were also detected by echocardiography. One of the positive cats died suddenly 1 year after diagnosis and at necropsy two decomposing D. immitis were found in the right ventricle and pulmonary artery. This is the first report of confirmed feline dirofilariosis in Greece. The detected proportion of infection in cats was 38% of the respective canine infection in the examined shelter. The results of the present study underline the high risk of infection of cats living in enzootic areas and the imperative character of preventive measures in such conditions.

  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