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   31857篇
  免费   1982篇
  国内免费   185篇
耳鼻咽喉   301篇
儿科学   735篇
妇产科学   649篇
基础医学   4713篇
口腔科学   1363篇
临床医学   2917篇
内科学   7388篇
皮肤病学   818篇
神经病学   2804篇
特种医学   800篇
外科学   3345篇
综合类   100篇
一般理论   14篇
预防医学   2744篇
眼科学   638篇
药学   2306篇
中国医学   131篇
肿瘤学   2258篇
  2024年   43篇
  2023年   318篇
  2022年   740篇
  2021年   1197篇
  2020年   727篇
  2019年   977篇
  2018年   1078篇
  2017年   807篇
  2016年   944篇
  2015年   1037篇
  2014年   1391篇
  2013年   1691篇
  2012年   2693篇
  2011年   2806篇
  2010年   1475篇
  2009年   1252篇
  2008年   2157篇
  2007年   2086篇
  2006年   1936篇
  2005年   1829篇
  2004年   1586篇
  2003年   1402篇
  2002年   1240篇
  2001年   191篇
  2000年   130篇
  1999年   158篇
  1998年   218篇
  1997年   183篇
  1996年   157篇
  1995年   120篇
  1994年   106篇
  1993年   92篇
  1992年   83篇
  1991年   84篇
  1990年   67篇
  1989年   78篇
  1988年   59篇
  1987年   50篇
  1986年   52篇
  1985年   47篇
  1984年   58篇
  1983年   48篇
  1982年   46篇
  1981年   38篇
  1979年   23篇
  1977年   18篇
  1967年   15篇
  1934年   16篇
  1933年   20篇
  1932年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The purpose of this article is to overview vector-borne rickettsioses in North Africa, focusing on epidemiologic aspects, clinical features, diagnosis procedures, and treatment. The protective measures, the exposure to risk, and the dynamics of endemic emerging and re-emerging diseases in the region are detailed to minimize the risk when traveling in this area. In addition, the article describes the scientific contribution on the rickettsial field of North-African researchers from the beginning of the 20th century until today.  相似文献   
992.
AIM: To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice.METHODS: Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe2+) iron salt or ferric (Fe3+) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated using quantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria.RESULTS: Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg protein vs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po - 6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po - 6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood.CONCLUSION: Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.  相似文献   
993.
Background: Upper aerodigestive symptoms (UADS) have been reported by patients who have had thyroidectomies. This study evaluated the long-term prevalence of UADS after thyroidectomy in patients who did and who did not have intraoperative neuromonitoring (IONM). Methods: This was a cross-sectional study of patients with normal vocal fold mobility who had a thyroidectomy. It included patients who did and did not have this surgery with IONM. All patients answered a questionnaire regarding UADS occurring one or more years after thyroidectomy. The questionnaire dealt with UADS relating to voice and swallowing symptoms and sought to quantify their severity. The 208 patients who underwent thyroidectomy without IONM were designated the control group (CG). The 100 patients who underwent thyroidectomy with IONM were designated the neuromonitored group (NMG). Results: The proportion of patients in the CG who reported UADS was 45%; 25.9% of these patients reported voice symptoms, and 33.6% reported swallowing symptoms. The proportion of patients in the NMG who reported UADS was 39%; 27% of these patients reported voice symptoms, and 22% reported swallowing symptoms. Thus, patients in the CG had more swallowing symptoms and a greater severity of UADS-related symptoms than patients in the NMG. Conclusions: In this study, IONM had a favorable effect in terms of decreasing the prevalence and severity of UADS occurring one year or more after thyroidectomy.  相似文献   
994.
Background: Epidemiological studies have shown a higher risk of thyroid cancer among individuals who have a relative with papillary thyroid cancer (PTC) compared to those without a family history. This study evaluated the prevalence of thyroid cancer among subjects with only one first-degree relative (sibling) with PTC who had no palpable nodules, factors predictive of this malignancy, and the characteristics of tumors discovered during ultrasonographic screening. Methods: A total of 757 siblings of 447 patients with apparently sporadic PTC were examined. Nodules were palpable in 34 subjects (excluded). The 723 individuals without palpable abnormalities were submitted to thyroid ultrasonography and comprised the study group. The control group, consisting of 241 volunteers without a family history of thyroid cancer matched for gender and age to the study group, was also submitted to thyroid ultrasonography. All nodules ≥5?mm were examined by fine-needle aspiration cytology. Subjects with benign cytology were not submitted to surgery, whereas the subjects having malignant, suspicious for a malignancy, indeterminate, or inadequate cytology were referred for thyroidectomy. Results: Ultrasonography detected nodules in 303 (41.9%) study subjects. PTC was observed in 5.94% of the 723 subjects studied (8% women and 3.75% men, p=0.017) and in 14.2% of the 303 subjects with nonpalpable nodular disease. In the control group, 80 (33.2%) of the volunteers had nodules. PTC was observed in 1.2% of them and in 3.8% of those with nodular disease. In addition, 7.17% of the 447 patients had siblings with PTC detected only by ultrasonography. Multicentricity of the tumor was the main predictor of the presence of malignancy in siblings of patients with PTC. Twenty-two subjects (3% of those screened) had tumors that were not intrathyroid microcarcinomas (whereas all three tumors detected in controls were intrathyroid microcarcinomas). Screening permitted an earlier diagnosis of the disease when compared to siblings with a spontaneous diagnosis. Conclusions: The present results favor ultrasonographic screening of first-degree relatives of patients with apparently sporadic multicentric PTC, especially among women.  相似文献   
995.
996.
997.
998.
999.
1000.
We have investigated whether the quality of dietary fat and supplementation with coenzyme Q(10) (CoQ) modifies expression of genes related with inflammatory response and endoplasmic reticulum stress in elderly persons. Twenty participants received three diets for 4 weeks each: Mediterranean diet + CoQ (Med + CoQ), Mediterranean diet (Med), and saturated fatty acid-rich diet (SFA). After 12-hour fast, volunteers consumed a breakfast with a fat composition similar to that consumed in each of the diets. Med and Med + CoQ diets produced a lower fasting calreticulin, IL-1b, and JNK-1 gene expression; a lower postprandial p65, IKK-b, MMP-9, IL-1b, JNK-1, sXBP-1, and BiP/Grp78 gene expression; and a higher postprandial IkB-a gene expression compared with the SFA diet. Med + CoQ diet produced a lower postprandial decrease p65 and IKK-b gene expression compared with the other diets. Our results support the anti-inflammatory effect of Med diet and that exogenous CoQ supplementation in synergy with a Med diet modulates the inflammatory response and endoplasmic reticulum stress.  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