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   231588篇
  免费   21124篇
  国内免费   7997篇
耳鼻咽喉   1392篇
儿科学   6119篇
妇产科学   3759篇
基础医学   42077篇
口腔科学   4872篇
临床医学   14844篇
内科学   41001篇
皮肤病学   3844篇
神经病学   18737篇
特种医学   5524篇
外国民族医学   59篇
外科学   19618篇
综合类   26168篇
现状与发展   32篇
预防医学   11271篇
眼科学   2664篇
药学   28655篇
  48篇
中国医学   7442篇
肿瘤学   22583篇
  2023年   3345篇
  2022年   6542篇
  2021年   9618篇
  2020年   8026篇
  2019年   9948篇
  2018年   9480篇
  2017年   8645篇
  2016年   8109篇
  2015年   9533篇
  2014年   13623篇
  2013年   15025篇
  2012年   13363篇
  2011年   15673篇
  2010年   13253篇
  2009年   12729篇
  2008年   12004篇
  2007年   10731篇
  2006年   9749篇
  2005年   8251篇
  2004年   7241篇
  2003年   6232篇
  2002年   4807篇
  2001年   4135篇
  2000年   3475篇
  1999年   3149篇
  1998年   2673篇
  1997年   2441篇
  1996年   2097篇
  1995年   1751篇
  1994年   1534篇
  1993年   1268篇
  1992年   1059篇
  1991年   959篇
  1990年   795篇
  1989年   678篇
  1988年   588篇
  1986年   478篇
  1985年   1728篇
  1984年   2517篇
  1983年   1615篇
  1982年   1817篇
  1981年   1638篇
  1980年   1375篇
  1979年   1202篇
  1978年   1035篇
  1977年   878篇
  1976年   975篇
  1975年   683篇
  1974年   585篇
  1973年   605篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
31.
目的:观察电针双侧"足三里"穴对脾气虚模型大鼠小肠黏膜上皮组织内的钠依赖葡萄糖转运体(SGLT1),葡萄糖运载蛋白2(GLUT2)的基因及蛋白表达的影响。方法:将40只SD雄性大鼠随机分为正常组、脾气虚组、足三里组、非经非穴组,每组10只。所有大鼠均在SPF级动物实验中心饲养。除正常组外,其余3组均采用劳倦过度和不规则饮食复合法建立脾气虚证的大鼠模型。造模成功之后,对足三里组、非经非穴组大鼠分别进行电针"足三里"穴、非经非穴点干预处理7天。采用HE染色方法观察各组大鼠小肠黏膜组织形态变化;采用荧光定量PCR法检测大鼠小肠黏膜上皮的SGLT1和GLUT2的mRNA表达水平;采用蛋白质免疫印迹法(WB)检测大鼠小肠黏膜上皮组织内的SGLT1和GLUT2的蛋白含量变化。结果:脾气虚组大鼠小肠黏膜组织部分损伤,足三里组的小肠黏膜组织有一定程度的恢复;脾气虚组和非经非穴组大鼠小肠黏膜组织内的SGLT1和GLUT2蛋白和基因表达水平均明显低于正常组(P 0. 05);足三里组大鼠小肠黏膜组织内的SGLT1和GLUT2蛋白和基因表达水平相比于脾气虚组有所升高(P 0. 05),非经非穴组未见显著性差异(P 0. 05)。结论:电针"足三里"穴可以调节脾气虚大鼠小肠黏膜上皮组织内的SGLT1和GLUT2基因及蛋白的异常表达,参与小肠对葡萄糖的吸收作用进而改善脾气虚证。  相似文献   
32.
33.
孤独症谱系障碍(ASD)是影响儿童健康的严重公共问题之一,以社交沟通障碍、兴趣或活动范围狭窄以及重复刻板行为为特征。近年来越来越多的研究显示,ASD患儿维生素D(VitD)水平明显低于同龄健康儿童,VitD缺乏可能与ASD的发病机制相关。本文就VitD与ASD的相关研究进行综述。  相似文献   
34.
35.
目的:探讨D6S1043、D12S391基因座的基因多态性对主动攻击行为的影响。方法:应用聚合酶链反应技术结合毛细管电泳法对114例男性主动攻击行为者(研究组)及120名健康男性(对照组)进行D6S1043、D12S391基因座的基因型及等位基因检测,分析D6S1043、D12S391基因座多态性与主动攻击行为的相关性。结果:研究组D6S1043基因座中12~19基因型频率(13.16%)明显高于对照组(1.67%)(P0.05);两组等位基因频率差异无统计学意义;两组D12S391基因座的基因型及等位基因频率差异无统计学意义。结论:D6S1043基因座中12~19基因型可能主动攻击行为有关。  相似文献   
36.
《Vaccine》2016,34(39):4724-4731
Human papillomavirus (HPV) infection is the most common sexually transmitted disease worldwide. HPVs are oncogenic small double-stranded DNA viruses that are the primary causal agent of cervical cancer and other types of cancers, including in the anus, oropharynx, vagina, vulva, and penis. Prophylactic vaccination against HPV is an attractive strategy for preventing cervical cancer and some other types of cancers. However, there are few safe and effective vaccines against HPV infections. Current first-generation commercial HPV vaccines are expensive to produce and deliver.The goal of this study was to develop an alternate potent HPV recombinant L1-based vaccines by producing HPV virus-like particles into a vaccine that is currently used worldwide. Live attenuated measles virus (MV) vaccines have a well-established safety and efficacy record, and recombinant MV (rMV) produced by reverse genetics may be useful for generating candidate HPV vaccines to meet the needs of the developing world.We studied in non-human primate rMV-vectored HPV vaccine in parallel with a classical alum adjuvant recombinant HPV16L1 and 18L1 protein vaccine produced in Pichia pastoris. A combined prime-boost approach using both vaccines was evaluated, as well as immune interference due to pre-existing immunity against the MV.The humoral immune response induced by the MV, Pichia-expressed vaccine, and their combination as priming and boosting approaches was found to elicit HPV16L1 and 18L1 specific total IgG and neutralizing antibody titres. Pre-existing antibodies against measles did not prevent the immune response against HPV16L1 and 18L1.  相似文献   
37.
There is an increasing number of effective therapies for fracture prevention in adults at risk of osteoporosis. However, shortcomings in the evidence underpinning our management of osteoporosis still exist. Evidence of antifracture efficacy in the groups of patients who most commonly use calcium and vitamin D supplements is lacking, the safety of calcium supplements is in doubt, and the safety and efficacy of high doses of vitamin D give cause for concern. Alendronate, risedronate, zoledronate and denosumab have been shown to prevent spine, nonspine and hip fractures; in addition, teriparatide and strontium ranelate prevent both spine and nonspine fractures, and raloxifene and ibandronate prevent spine fractures. However, most trials provide little information regarding long‐term efficacy or safety. A particular concern at present is the possibility that oral bisphosphonates might cause atypical femoral fractures. Observational data suggest that the incidence of this type of fracture increases steeply with duration of bisphosphonate use, resulting in concern that the benefit–risk balance may become negative in the long term, particularly in patients in whom the osteoporotic fracture risk is not high. Therefore, reappraisal of ongoing use of bisphosphonates after about 5 years is endorsed by expert consensus, and ‘drug holidays’ should be considered at this time. Further studies are needed to guide clinical practice in this area.  相似文献   
38.
BACKGROUND Metabolic disturbances including changes in serum calcium,magnesium or phosphate(P) influence the prevalence of type 2 diabetes mellitus(DM).We assessed the importance of serum P in elderly patients with type 2 DM vs nondiabetes mellitus(non-DM) in relation to renal function.AIM To determine the association between serum P and serum glucose or insulin resistance in diabetic and non-diabetic patients.METHODS One hundred-ten subjects with a mean age of 69.02±14.3 years were enrolled.Twenty-nine of the participants had type 2 DM(26.4%).The incidence of hypertension,smoking and receiving vitamin D(vitD) derivates were recorded.The participants were classified by both estimated glomerular filtration rate(eGFR) and albuminuria categories according to the Kidney Disease Improving Global Outcomes 2012 criteria.RESULTS We divided the patients in two groups according to the P cut-off point related to DM value.A comparison between high and low P showed that body mass index30.2±6.3 vs 28.1±4.6(P=0.04),mean glucose 63.6 vs 50.2(P=0.03),uric acid 6.7±1.6 vs 6.09±1.7(P=0.05),mean intact-parathyroid hormone 68.06 vs 47.4(P=0.001),systolic blood pressure 147.4±16.7 vs 140..2±16.1(P=0.02),mean albuminuria 63.2 vs 50.6(P=0.04) and eGFR 45.6±22.1 vs 55.4±21.5(P=0.02)were significantly different.χ~2 tests showed a significant association between high P and DM,hypertension,receiving vitD,smoking and eGFR stage(χ~2=6.3,P=0.01,χ~2=3.9,P=0.03,χ~2=6.9,P=0.009,χ~2=7.04,P=0.01 and χ~2=7.36,P=0.04,respectively).The adjusted model showed that older age,female gender and increased body mass index were significant predictors of type 2 DM when entering the covariates.CONCLUSION High serum P contributes to vascular and metabolic disturbances in elderly patients with type 2 DM and renal impairment.  相似文献   
39.
文题释义:股骨头坏死中日友好医院分型的有限元分析:根据李子荣等提出的中日友好医院分型,建立股骨头坏死三维模型,分为 M型(内侧型)、C型(中央型)和 L型(外侧型),其中 L型包括L1型(次外侧型)、L2型(极外侧型)和 L3型(全头型)。通过对建立的模型进行有限元分析,为该分型的保髋治疗提供了一定力学依据,显示外侧柱的存留是精准预防塌陷的重要因素,为进一步实现个体化治疗提供力学基础。 腓骨支撑坏死股骨头保髋手术:是对于早中期股骨头坏死需要保留股骨头患者进行的一种手术方式。首先需对股骨头进行髓芯减压,清除一定坏死骨,空腔填塞松质骨(髂骨为主),打压结实后植入腓骨(异体或自体)支撑,给坏死区的提供力学支撑及生物学修复,预防股骨头进一步坏死及塌陷。 背景:研究报道股骨头坏死的保髋疗效与外侧柱存留密切相关,中日友好医院分型是根据三柱结构确立的,对股骨头塌陷的预测准确性高。 目的:建立股骨头坏死中日友好医院分型各分型仿真的三维有限元模型,通过有限元分析各分型腓骨植入的力学变化,探讨外侧柱存留对保髋疗效的意义,为该分型的塌陷精准预测提供基础。 方法:建立正常股骨头、中日友好医院分型(M型、C型、L1型、L2型、L3型)股骨头坏死及其腓骨植入3组11种三维有限元模型,运用ANSYS软件进行有限元分析计算,观察各组模型的最大应力值、最大位移值及股骨头内部载荷传递模式。 结果与结论:①坏死组位移最大,应变最大,且因坏死分型不同而位移不同,位移变化如下:M型相似文献   
40.
BackgroundGrowth hormone (GH)-producing pituitary tumors account for 10 to 15% of pituitary tumors. The hypersecretion of GH may induce changes in the airway anatomy through the activation of Insulin-like Growth factor 1(IGF-1) pathway. We sought investigate the role IGF-1 as a potential predictive factor of difficult laryngoscopy in patients with GH-producing pituitary adenoma.MethodsThis study was a single center retrospective study. We included 33 patients undergoing transsphenoidal resection of GH-producing pituitary. We recorded demographic data, el-Ganzouri risk index (EGRI) and modified Look-Evaluate-Mallampati-Obstruction-Neck mobility (mLEMON) score, and pituitary hormone plasma levels. We performed ordinal logistic regression to analyze the relationship between IGF-1 and EGRI, mLEMON, and Cormack-Lehane Grade score and a multiple logistic regression to test the capability of EGRI, mLEMON and IGF-1 levels to predict Cormack-Lehane score. Receiver operating curve (ROC), area under the curve (AUC), and cut-off value of IGF-1 were calculated.ResultsOnly 14 (42.8%) and 12 (36.36%) patients showed predictive factors of difficult intubation according to EGRI and mLEMON score, respectively. IGF-1 significantly correlated with Cormack-Lehane (p = 0.005879) but not with mLEMON and EGRI (p = 0.3080 and 0.4146, respectively). In multiple regression model IGF-1 correlated only with Cormack-Lehane grade (p = 0.0089). Area under ROC was 0.8571 and cut-off value of IGF-1 was 186.15 ng/ml.ConclusionHigher IGF-1 levels correlate with the probability of having a higher Cormack-Lehane score; classical bedside scores, such as mLEMON and EGRI, were not able to predict difficult laryngoscopy in our population.  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