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   18827篇
  免费   2195篇
  国内免费   776篇
耳鼻咽喉   108篇
儿科学   318篇
妇产科学   280篇
基础医学   1901篇
口腔科学   559篇
临床医学   1723篇
内科学   2787篇
皮肤病学   106篇
神经病学   1061篇
特种医学   861篇
外国民族医学   6篇
外科学   4235篇
综合类   2814篇
现状与发展   3篇
预防医学   1642篇
眼科学   423篇
药学   1308篇
  3篇
中国医学   734篇
肿瘤学   926篇
  2024年   18篇
  2023年   236篇
  2022年   395篇
  2021年   731篇
  2020年   662篇
  2019年   645篇
  2018年   631篇
  2017年   555篇
  2016年   553篇
  2015年   583篇
  2014年   1122篇
  2013年   1264篇
  2012年   1027篇
  2011年   1175篇
  2010年   956篇
  2009年   1045篇
  2008年   1077篇
  2007年   1074篇
  2006年   989篇
  2005年   1004篇
  2004年   865篇
  2003年   747篇
  2002年   620篇
  2001年   553篇
  2000年   496篇
  1999年   398篇
  1998年   305篇
  1997年   309篇
  1996年   234篇
  1995年   213篇
  1994年   161篇
  1993年   151篇
  1992年   137篇
  1991年   105篇
  1990年   88篇
  1989年   58篇
  1988年   63篇
  1987年   54篇
  1986年   42篇
  1985年   77篇
  1984年   67篇
  1983年   63篇
  1982年   49篇
  1981年   55篇
  1980年   44篇
  1979年   25篇
  1978年   21篇
  1977年   20篇
  1976年   11篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
1.
阿尔茨海默病是一种进行性且不可逆转的神经系统疾病,由于视网膜和中枢神经系统有相似的胚胎起源和生理特征,眼科检查可提供简单无创的诊断方法。光学相干断层扫描技术(OCT)能够精确地测量视网膜各个组织层面的厚度,以评估视网膜的退行性改变,光学相干断层扫描血管成像(OCTA)可以提供高分辨率三维成像,从而更直观地检测视网膜血管的变化,间接地反映脑神经元和血管的病理特征。就OCT测量视网膜厚度及OCTA测量视网膜血流变化在阿尔茨海默病诊断中的研究进展进行综述。  相似文献   
2.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
3.
《Pancreatology》2022,22(8):1175-1180
BackgroundHepatic steatosis has been described as a common finding in adults following total pancreatectomy with islet autotransplantation (TPIAT) but it is unknown if this occurs in children and adolescents.ObjectivesTo define the frequency of post-TPIAT hepatic steatosis in a sample of children and adolescents and to identify clinical predictors of incident steatosis post-TPIAT.MethodsIn this prospective study, consecutive participants at least 1-month post-TPIAT underwent a liver MRI with proton density fat fraction (PDFF) and blood draw at our pediatric academic medical center between April 2021 and January 2022. Comparison clinical pre-TPIAT liver MRI or ultrasound and insulin use and graft function data were extracted from the medical record. T-tests were used for the comparison of means across continuous variables between participants with and without post-TPIAT steatosis.ResultsA total of 20 participants (mean: 13 ± 4 years; 12 female) were evaluated. Mean liver PDFF at research MRI was 7.4 ± 6.2% (range: 2–25%). Seven participants (35%) had categorical hepatic steatosis (PDFF>5%) post-TPIAT, five of whom had pre-TPIAT steatosis, reflecting a 13% (2/15; 95% CI: 2–40%) incidence of post-TPIAT steatosis. Participant characteristics were not significantly different between subgroups with and without post-TPIAT steatosis. Mean PDFF at research MRI was not different between graft function subgroups (7.5% optimal/good vs. 7.3% marginal/failure; p = .96).ConclusionOur study shows a moderate prevalence but low incidence of hepatic steatosis in a small sample of children and adolescents post-TPIAT. This study raises questions about a causal relationship between TPIAT and hepatic steatosis.  相似文献   
4.
5.
6.
7.
目的:探究复方丹参滴丸对老年冠心病患者血流变学、血脂及炎性反应递质的影响。方法:选取2015年1月至2017年12月海南省人民医院收治的老年冠心病患者154例作为研究对象,按照随机数字表法随机分为对照组和观察组,每组77例。对照组采用常规西药治疗,观察组在此基础上加服复方丹参滴丸。比较治疗前后2组患者的血流变学、血脂、炎性反应递质和疗效。结果:观察组治疗有效率为92.21%,明显高于对照组治疗有效率79.22%,差异有统计学意义(P<0.05)。治疗后,2组总胆固醇(TC)、三酰甘油(TG)和低密度脂蛋白(LDL)水平均升高,差异有统计学意义(P<0.05),且观察组高于对照组,2组差异有统计学意义(P<0.05)。2组血流变学指标、高密度脂蛋白(HDL)、IL-6和TNF-α水平治疗后均降低(P<0.05),且观察组降低更明显,差异有统计学意义(P<0.05)。结论:复方丹参滴丸联合常规西药治疗冠心病患者,能够调节脂代谢,降低炎性反应,改善血流变学。  相似文献   
8.
目的探索白藜芦醇对酒精诱导雄性大鼠骨量减少和骨强度降低的影响。方法 30只12周雄性大鼠随机分为对照组、模型组和治疗组3组,每组10只。模型组和治疗组大鼠给予0.4 mL/100 g的20%乙醇溶液,每周3次。治疗组接受白藜芦醇40 mg/kg治疗,每日一次,治疗为期12周。治疗结束时收集血清和股骨对治疗结果进行评价。结果治疗12周后,治疗组的股骨骨密度较模型组显著升高,差异有统计学意义(P0.05);Mircro-CT显示治疗组大鼠股骨干骺端较模型组具有更多骨小梁以及更佳的骨微观参数,差异有统计学意义(P0.05);生物力学结果显示治疗组股骨的极限载荷和峰值负荷较模型组显著升高,差异有统计学意义(P0.05);而血清检测结果表明治疗组的碱性磷酸酶和骨钙素较模型组明显降低,差异有统计学意义(P0.05)。结论白藜芦醇对酒精诱导雄性大鼠骨量减少和骨强度降低有一定的保护作用。  相似文献   
9.
目的:探讨MRI在浸润性小叶癌(ILC)术前诊断中的应用价值,并评估乳腺密度对其影响。方法:选取75例术前30天内行MRI检查的I-Ⅲ期ILC患者列入本项研究,根据腺体含量评估乳腺密度,在MRI下测量肿瘤大小,并对比其与病理大小的一致性。结果:75例入组患者中26例(34.7%)患者经MRI评估发现新的可疑病灶,20例(26.7%)患者改变了手术方式。高密度乳腺型患者额外病灶检出率明显高于低密度乳腺型患者(51.6% vs 22.7%,P=0.010)。MRI评估肿瘤大小在低密度乳腺型患者中容易被低估(36.4% vs 12.9%,P=0.024),在高密度乳腺型患者中容易被高估(6.8% vs 29.0%,P=0.010),但两组患者与病理大小一致性的比例无明显差异。结论:ILC患者术前乳腺MRI检查能够提高额外恶性肿瘤的检出率,而乳腺密度是影响MRI评估的重要因素。  相似文献   
10.
PurposeEffective written communication directly affects health care outcomes. Since 2016, the complex language of state-mandated breast density notifications (BDNs) has been challenged, because it is perceived to be beyond the comprehension of most patients. The aim of this study was to assess whether a revised BDN written at a lower reading grade level improves understanding compared with the current state-mandated BDN.MethodsA revised notification with similar content to the current state-mandated BDN was developed. Both notifications were presented to patients for direct comparison, using a paper survey asking questions that evaluated patients’ perceptions and convictions associated with breast density. Surveys were distributed at four outpatient imaging centers to screening mammography patients.ResultsThe current BDN’s mean readability metric was 13.4, and that of the revised BDN was 6.6. Five hundred surveys were analyzed. Survey data demonstrated that 56.6% of all women perceived that dense breast tissue results indicated a “high” associated lifetime breast cancer risk from the current state-mandated BDN compared with only 2.2% with the revised notification (P < .001). Nearly all women were more likely to initiate discussions with their providers regarding their breast tissue density after reading the revised notification (96.0%) as opposed to the current state-mandated BDN (32.8%; P < .001).ConclusionsA significant portion of women misinterpret the intended messages of the current state-mandated BDN. Thus, a revised notification at a lower reading grade level may improve understanding of breast density, leading to improved individualized breast cancer screening for women with dense breasts.  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