首页 | 官方网站   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   2364篇
  免费   202篇
  国内免费   54篇
医药卫生   2620篇
  2023年   29篇
  2022年   58篇
  2021年   78篇
  2020年   61篇
  2019年   81篇
  2018年   54篇
  2017年   60篇
  2016年   85篇
  2015年   74篇
  2014年   135篇
  2013年   145篇
  2012年   168篇
  2011年   186篇
  2010年   154篇
  2009年   99篇
  2008年   84篇
  2007年   134篇
  2006年   116篇
  2005年   111篇
  2004年   111篇
  2003年   96篇
  2002年   78篇
  2001年   56篇
  2000年   63篇
  1999年   43篇
  1998年   42篇
  1997年   31篇
  1996年   19篇
  1995年   19篇
  1994年   26篇
  1993年   14篇
  1992年   17篇
  1991年   11篇
  1990年   20篇
  1989年   15篇
  1988年   10篇
  1987年   6篇
  1986年   8篇
  1985年   4篇
  1983年   2篇
  1982年   1篇
  1981年   4篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
排序方式: 共有2620条查询结果,搜索用时 507 毫秒
21.
目的 研究含不同浓度碘(I-)的乳过氧化物酶-过氧化氢-硫氰化物系统(LPO-H2O2-SCN-)对变异链球菌生长、黏附、产水不溶性细胞外多糖以及葡萄糖基转移酶(GTF)活性的影响。方法 选用 S.mutans ATCC 25175为实验菌株。采用菌落形成单位(CFU)计数法进行生长实验;用分光光度计法测定细菌的黏附抑制率;用蒽酮法测定水不溶性细胞外多糖的质量浓度;用蒽酮法测定还原糖量,计算 GTF活性。结果 随着 I-浓度的增高,含I-的 LPO-H2O2-SCN-抗菌系统对 S.mutans致龋力的抑制作用增强。当I-≥100 μmol•L-1时,对 S.mutans的生长抑制明显高于对照组( P<0.05);且当I-≥1 000 μmol•L-1时,对S.mutans的生长抑制显著高于以硫氰酸盐(SCN-)为单底物的实验组(P<0.05);当I-≥100 μmol•L-1时,对S.mutans的黏附抑制率达到50%以上,水不溶性细胞外多糖生成量明显减少( P<0.05), GTF活性也明显降低(P<0.05)。结论 通过增加 I-的浓度,可以抵消生理浓度的 SCN-的抑制作用,使含I-的LPO-H2O2-SCN-系统能显著抑制变异链球菌的生长、黏附、水不溶性细胞外多糖生成和GTF活性。  相似文献   
22.
PURPOSE: Our objective was to establish thyroid volume by sonography in Brazilian schoolchildren and to correlate thyroid volume with anthropometric characteristics. METHODS: Sonographic studies of thyroid volume were conducted in 1,977 schoolchildren (6-14 years old) from 21 villages and towns in Central Brazil. Iodine concentration was analyzed in urine specimens and in salt samples obtained from the children's homes. Thyroid volumes were also compared with volumes reported for other countries. RESULTS: Age, height, and weight correlated with thyroid volume. Thyroid volumes for boys and girls were generally lower than those obtained in Europe and comparable to those obtained in Malaysia and Iran. Urinary iodine excretion was considered elevated in about half of the Brazilian schoolchildren, and the iodine content of salt samples was more than 50 ppm in 58%. CONCLUSIONS: We observed relatively smaller thyroid gland volumes in Brazilian schoolchildren as compared with those reported in Europe. This was apparently due to a higher iodine intake in our population.  相似文献   
23.
含碘清洗消毒剂的研究   总被引:7,自引:2,他引:7  
试验表明,以有效碘浓度为250mg/L的含碘清洗消毒剂溶液作用10分钟,可将大肠杆菌与金黄色葡萄球菌杀灭99.9%以上。该清洗消毒剂无毒,无刺激,对铝有轻度腐蚀,除油效果与洗洁精相似.  相似文献   
24.
Background: The histological characteristics of follicular thyroid carcinomas (FTCs) are important predictors of prognosis, and lesions can be classified as either minimally invasive follicular carcinoma (MIFC) or widely invasive follicular carcinoma (WIFC) based on histopathological characteristics. There has been controversy surrounding the histological classification of FTC, which can present challenges to clinicians attempting to deliver accurate prognostic information to their patients. The aim of the present study was to examine cases of metastatic FTC for characteristics that may predict aggressive tumour behaviour. Methods: The Monash University Endocrine Surgery Unit database was searched for patients with FTC. The histopathology reports were collated for these patients to confirm the diagnosis of FTC, classify patients into MIFC versus WIFC, and examine for key characteristics such as the capsular and/or vascular invasion. The thyroid specimens from patients with metastatic FTC were examined by reviewing pathologists. It was hypothesized that patients with metastatic disease would likely have WIFC as their primary lesion. Results: There were 64 patients with FTC identified during the period of 1997–2009. Of these, 10 patients were found to have metastatic disease. On review of the histopathology, three patients were found to have WIFC,four patients had MIFC and three patients did not have definite features of FTC found in the thyroid gland. Conclusion: Currently accepted histological classification of FTC is inadequate and fails to accurately predict patients with distant metastatic disease and a more aggressive clinical course. It is thus the policy of our unit to recommend total thyroidectomy and radioactive iodine ablation for all patients with FTC.  相似文献   
25.
BACKGROUND: Iodine 123-metaiodobenzylguanidine (MIBG) imaging has been used to assess cardiac sympathetic nerve abnormalities. To determine the role of MIBG imaging as a measure of generalized sympathetic nerve activity, MIBG imaging was evaluated with muscle sympathetic nerve activity (MSNA) and plasma norepinephrine (noradrenaline) level in patients with old myocardial infarction. METHODS: Myocardial MIBG scintigraphy, MSNA and plasma norepinephrine measurement were performed within 3 days in 35 patients with old myocardial infarction. Patients were divided into three groups according to their ejection fraction (EF); preserved (EF > or = 50%, 12 patients), intermediate (35% < EF < 50%, 13 patients), or depressed (EF < or = 35%, 10 patients).The heart to mediastinum (H/M) ratio was obtained 4 h after tracer injection from the chest anterior view image. MIBG washout rate was calculated from the early and delayed images. MSNA was recorded by microneurography. RESULTS: Plasma norepinephrine level had weak negative correlations with early H/M ratio (r = 0.37, P<0.05) and delayed H/M ratio (r = 0.33, P<0.05), and a positive correlation with MIBG washout rate (r = 0.54, P<0.01). MSNA had weak negative correlations with early H/M ratio (r = 0.51, P<0.05) and delayed H/M ratio (r = 0.52, P<0.05). However, a strong correlation was found between MSNA and MIBG washout rate (r = 0.88, P<0.001). Despite no significant differences in plasma norepinephrine level and H/M ratio, patients with intermediate and depressed EF had higher MIBG washout rate and MSNA compared with those with preserved EF. CONCLUSIONS: Increased in cardiac sympathetic nerve activity was associated with augmented sympathetic outflow of the skeletal muscle and hence, MIBG washout rate allow the assessment of general sympathetic nerve activity.  相似文献   
26.
[目的]研究比较纳米硒和亚硒酸钠对高碘致小鼠部分组织氧化损伤的干预作用。[方法]将48只雄性昆明小鼠被随机分为适碘组[50μg/L碘酸钾(KIO3)]、高碘组(3 000μg/L KIO3)、亚硒酸钠组(3 000μg/L KIO3+0.193 mg/kg硒)、纳米硒组(3 000μg/L KIO3+0.193 mg/kg硒),每组12只。4周后处死小鼠,测定血清、肝脏、肾脏组织的谷胱甘肽过氧化物酶(GSH-Px)活力、以及丙二醛(MDA)水平。观察甲状腺病理变化。[结果]与适碘组相比,高碘组血清、肝脏和肾脏中GSH-Px活力均明显下降,差异有统计学意义(P<0.05);肝脏中MDA含量下降,差异有统计学意义(P<0.05);肝脏和肾脏脏器系数均增加,差异有统计学意义(P<0.05)。与高碘组相比,亚硒酸钠组血清和肝脏中GSH-Px活力均明显升高,差异有统计学意义(P<0.05);肾脏中MDA含量增加,差异有统计学意义(P<0.05);肝脏脏器系数下降,差异有统计学意义(P<0.05);血清和肝脏中MDA含量均下降。纳米硒组血清、肝脏和肾脏中GSH-Px活力均明显增加,差异有统计学意义(P<0.05);血清和肝脏中MDA含量均明显下降,在肾脏中增加,差异有统计学意义(P<0.05);肾脏脏器系数下降,差异有统计学意义(P<0.05)。高碘组甲状腺组织出现弥漫胶质性甲状腺肿。[结论]高碘摄入可致小鼠氧化性损伤,补硒有一定干预作用,纳米硒的干预效果优于亚硒酸钠。  相似文献   
27.

Background

Thyroid cancer is the most common malignancy of the endocrine system, representing 3.8% of all new cancer cases in the United States and is the ninth most common cancer overall. The American Cancer Society estimates that 62,450 people in the United States will be diagnosed with thyroid cancer in 2015, and 1950 deaths will result from the disease.

Objective

To review the current approach to the diagnosis and treatment of patients with thyroid cancer.

Discussion

Over the past 3 decades, there has been a dramatic increase in the number of people diagnosed with thyroid cancer, which may be attributable to the wide use of imaging studies, including ultrasounds, computed tomography, magnetic resonance imaging, and positron emission tomography scans that incidentally detect thyroid nodules. Thyroid cancer is divided into several main types, with papillary thyroid cancer being the most common. The treatment options for patients with thyroid cancer include the surgical removal of the entire thyroid gland (total thyroidectomy), radioactive iodine therapy, and molecular-targeted therapies with tyrosine kinase inhibitors. This article summarizes the diagnosis and treatment of thyroid cancer, with recommendations from the American Thyroid Association regarding thyroid nodules and differentiated thyroid cancer. Recently approved drugs and treatment trends are also explored.

Conclusion

The prognosis and treatment of thyroid cancer depend on the tumor type and its stage at the time of diagnosis. Many thyroid cancers remain stable, microscopic, and indolent. The increasing treatment options for patients with thyroid cancer, including therapies that were recently approved by the US Food and Drug Administration, have kept the mortality rate from this malignancy low, despite the increase in its incidence. Early diagnosis and appropriate treatment can improve prognosis and reduce mortality.  相似文献   
28.
29.
Polythiophenes bearing a bornyl group as a side chain are synthesized. The polymers, which consist of multiple thiophenes and a substituted aromatic ring in the repeat unit, demonstrate right‐handed helicity in the film state. Results of energy level measurements show good agreement with the density functional theory calculation results for the model compounds. In situ electron spin resonance (ESR) studies indicate that increasing the number of unsubstituted thiophene units in the repeat unit increases susceptibility for the dopants. The chiral charge carriers are confirmed with ESR and circular dichroism spectroscopy measurements.

  相似文献   

30.
目的探讨碘代谢检测指标在甲状腺疾病手术治疗患者碘营养状况评估中的应用价值。方法收集31名健康志愿者和30例甲状腺疾病手术患者术前、术后血清、晨尿和24 h尿标本,应用电感耦合等离子体质谱法检测样本中的碘浓度,比较健康者和患者术前、术后血清碘、晨尿碘、晨尿碘/晨尿肌酐、24 h尿碘和24 h尿碘排泄量的差异,并分析健康者碘代谢检测指标的测定值对世界卫生组织、美国梅奥医学中心和奎斯特诊断公司提供的参考范围的验证率。结果甲状腺疾病术前组的晨尿碘/晨尿肌酐比值显著低于健康对照组(P<0.05),两组其他指标的差异无统计学意义(P均>0.05);患者经手术治疗后血清碘、晨尿碘和24 h尿碘水平均显著高于术前水平(P<0.05);健康对照组各项碘代谢指标的中位数均在3个实验室提供的参考范围内,但仅有血清碘、晨尿碘及41~70岁人群的晨尿碘/晨尿肌酐比值与美国梅奥医学中心提供的参考范围的验证率大于90%;晨尿碘/晨尿肌酐比值的受试者工作特征曲线下面积最大,为0.737。结论晨尿碘/晨尿肌酐比值可能用于甲状腺疾病手术治疗患者碘营养状况的评估。  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-23

京公网安备 11010802026262号