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   39716篇
  免费   3797篇
  国内免费   1079篇
耳鼻咽喉   238篇
儿科学   1474篇
妇产科学   858篇
基础医学   4182篇
口腔科学   509篇
临床医学   3480篇
内科学   7394篇
皮肤病学   433篇
神经病学   1591篇
特种医学   1190篇
外国民族医学   5篇
外科学   3585篇
综合类   4105篇
预防医学   4204篇
眼科学   440篇
药学   6245篇
  13篇
中国医学   1998篇
肿瘤学   2648篇
  2024年   33篇
  2023年   970篇
  2022年   1355篇
  2021年   2095篇
  2020年   2079篇
  2019年   2011篇
  2018年   1803篇
  2017年   1639篇
  2016年   1523篇
  2015年   1583篇
  2014年   2852篇
  2013年   3110篇
  2012年   2305篇
  2011年   2586篇
  2010年   2027篇
  2009年   1999篇
  2008年   2047篇
  2007年   1923篇
  2006年   1523篇
  2005年   1421篇
  2004年   1160篇
  2003年   952篇
  2002年   792篇
  2001年   684篇
  2000年   538篇
  1999年   469篇
  1998年   352篇
  1997年   321篇
  1996年   265篇
  1995年   246篇
  1994年   244篇
  1993年   199篇
  1992年   174篇
  1991年   183篇
  1990年   149篇
  1989年   108篇
  1988年   92篇
  1987年   78篇
  1986年   72篇
  1985年   119篇
  1984年   94篇
  1983年   88篇
  1982年   68篇
  1981年   74篇
  1980年   43篇
  1979年   48篇
  1978年   31篇
  1977年   18篇
  1976年   18篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
目的:探索体重指数(BMI)对不孕女性夫精宫腔内人工授精(IUI)周期妊娠结局的影响。方法:回顾性分析2015 年1 月—2020 年6 月于天津市中心妇产科医院生殖中心施行IUI 治疗的3 707 例患者的周期资料,按照BMI 分为3 组,A 组(正常 体质量组18.5 kg/m2≤BMI<23.0 kg/m2)、B 组(超重组23.0 kg/m2≤BMI<25.0 kg/m2)、C 组(肥胖组BMI≥25.0 kg/m2),比较各组间 一般资料以及妊娠结局。结果:在方案中,3 组间自然周期方案占比差异均有统计学意义(P<0.01),口服药物联合肌注促排药物 方案差异均有统计学意义(P<0.01);BMI 与活产率无关,B 组(OR=1.161,95% CI:0.861~1.565,P=0.328)以及C 组(OR=1.003, 95% CI=0.761~1.322,P=0.948)与A 组活产率差异无统计学意义;肌注促排药物(OR=1.425,95% CI:1.026~1.980,P=0.035) 以及口服药物联合肌注促排药物(OR=1.366,95% CI:1.038~1.796,P=0.026)是影响活产率的独立因素。肥胖(OR=2.784,95% CI:1.471~5.267,P=0.002)以及继发性不孕(OR=3.048,95% CI=1.454~6.389,P=0.003)是早期流产的危险因素。结论:肥胖以及继 发性不孕为早期流产的危险因素,促排药物可提高不孕患者IUI 活产率。  相似文献   
2.
燕霞  张慧  罗轶 《中国医院药学杂志》2022,42(20):2127-2131
目的: 建立气相色谱-三重四极杆质谱(GC-MS/MS)同时测定宽胸气雾剂中桉油精、龙脑、甲基丁香酚、异龙脑、α-红没药醇、榄香素、反式橙花叔醇、石竹烯、α-葎草烯、β-蒎稀、α-蒎稀、左旋樟脑等12种指标性成分方法。方法: 采用内标法,样品经乙醇稀释,GC-MS/MS测定,程序升温,MRM模式检测;并使用热图聚类和主成分分析法对数据进行统计分析。结果: 12种指标成分分别在1~10 ng·mL-1和50~1 000 ng·mL-1两个量级内呈线性;回收率为97.5%~104.8%,RSD为1.14%~2.89%(n=3);8批样品中上述成分含量分别为22.24~26.79,22.22~26.88,20.74~22.99,13.72~16.78,10.25~11.23,5.25~5.81,4.60~4.78,2.63~3.06,2.18~2.47,1.92~2.18,1.55~1.94,1.02~1.07 mg·mL-1;热图聚类分析结果表明同一企业不同批次样品整体质量一致性较好。结论: 该方法专属性强、灵敏度高、测定方法简便结果准确,可为宽胸气雾剂的质量控制提供检验依据。  相似文献   
3.
4.
AimThis review aims to summarize and discuss some of the most relevant clinical trials in epidemiology, diagnostics, and treatment of hypertension published in 2020 and 2021.Data synthesisThe trials included in this review are related to hypertension onset age and risk for future cardiovascular disease, reliability of different blood pressure monitoring methods, role of exercise-induced hypertension, treatment of hypertension in patients with SARS-CoV-2 infection, management of hypertension high-risk patient groups, e.g., in the elderly (≥80 years) and patients with atrial fibrillation, and the interplay between nutrition and hypertension, as well as recent insights into renal denervation for treatment of hypertension.ConclusionsHypertension onset age, nighttime blood pressure levels and a riser pattern are relevant for the prognosis of future cardiovascular diseases. The risk of coronary heart disease appears to increase linearly with increasing exercise systolic blood pressure. Renin-angiotensin system blockers are not associated with an increased risk for a severe course of COVID-19. In elderly patients, a risk-benefit assessment of intensified blood pressure control should be individually evaluated. A J-shaped association between cardiovascular disease and achieved blood pressure could also be demonstrated in patients with atrial fibrillation on anticoagulation. Salt restriction and lifestyle modification remain effective options in treating hypertensive patients at low cardiovascular risk. Sodium glucose co-transporter 2 inhibitors and Glucagon-like peptide-1 receptor agonists show BP-lowering effects. Renal denervation should be considered as an additional or alternative treatment option in selected patients with uncontrolled hypertension.  相似文献   
5.
6.
目的基于UHPLC-Q-Exactive-Orbitrap-MS技术阐明树舌灵芝主要成分,结合网络药理学探讨其防治新型冠状病毒肺炎的作用机制。方法采用UHPLC-Q-Exactive-Orbitrap-MS技术鉴定树舌灵芝的主要成分;采用Swiss Target Prediction数据平台对鉴定成分进行靶点预测,对核心靶基因进行GO和KEGG富集分析,运用Cytoscape 3.8.0绘制关联网络图,同时通过分子对接评价树舌灵芝核心成分与血管紧张素转化酶Ⅱ(ACE2)及3种新型冠状病毒(SARS-CoV-2)蛋白的结合作用。结果该研究从树舌灵芝中鉴定化合物62个;30个活性化合物主要作用在IL-6、PTGS2和MAPK1等32个核心靶点,通过PI3K/Akt、TNF及肺结核等多条与肺损伤保护相关通路,发挥防治COVID-19的作用;分子对接显示小白菊内酯、1,4-二羟基-2-萘甲酸和瑞香素等核心成分与ACE2及3种SARS-CoV-2蛋白的亲和作用较好。结论该研究初步阐明树舌灵芝的化学成分及潜在作用机制,为筛选树舌灵芝防治COVID-19的药效成分及深入阐明作用机制提供了科学的理论依据。  相似文献   
7.
Metastatic brain disease frequently complicates extra central nervous system (CNS) neoplastic disease, with an increase in reported incidence over time. Brain parenchyma is the commonest anatomical site, with other lesions involving the spinal cord, dura and tissues surrounding the CNS. Metastases are usually characterised by a well-defined border with surrounding brain, although some can show an infiltrative edge. The use of appropriate immunohistochemical panels can help identify the origin of most tumours, and molecular testing should be performed according to the site of origin even if performed on a previous specimen due to potential changes in molecular characteristics. Reliable detection of leptomeningeal metastasis using CSF cytology relies on examination of an adequate volume of fluid; immunocytochemistry and flow cytometry can also be useful in the correct settings. Advances in the field include liquid biopsies, where circulating biomarkers are examined, and the use of methylation profiling to identify primary tumours.  相似文献   
8.
Tsukamurella species are obligate aerobic, gram-positive, weak acid-fast, nonmotile bacilli. They are found in various environments, such as soil, water, sludge, and petroleum reservoir wastewater, and belong to the order Actinomycetales. In 2016, there was a reclassification of species within the genus Tsukamurella, merging the species Tsukamurella tyrosinosolvens (T. tyrosinosolvens) and Tsukamurella carboxydivorans. Tsukamurella species are clinically considered to be a rare opportunistic pathogen, because most reported cases have been related to bacteremia and intravascular prosthetic devices and immunosuppression. To date, it has been isolated only from human specimens, and has always been associated with clinical disease; human infections are very rare. Reported infections have included pneumonia, brain abscesses, catheter-related bloodstream infections, ocular infections, bacteremia, and sepsis presenting with septic pulmonary emboli in patients who are immunocompromised. To date, there is no commercially available test for identification. On the other hand, sequence-based identification, including matrix-assisted laser desorption ionization time-of-flight mass spectrometry, is an alternative method for identifying clinical isolates that are either slow growers or difficult to identify through biochemical profiling. The golden standards for diagnosis and optimal management still remain to be determined. However, newer molecular biological techniques can provide accurate identification, and contribute to the appropriate selection of definitive therapy for infections caused by this organism. Combinations of several antimicrobial agents have been proposed for treatment, though the length of treatment for infections has yet to be determined, and should be individualized according to clinical response. Immunocompromised patients often experience severe cases due to infection, and life-threatening T. tyrosinosolvens events associated with dissemination and/or failure of source control have occurred. Favorable prognoses can be achieved through earlier identification of the cause of infection, as well as successful management, including appropriate antibiotic therapy together with source control. Further analyses of similar cases are required to establish the most adequate diagnostic methods and treatment regimens for infections.  相似文献   
9.
AimsThis review aims to provide an update of available methods for imaging calcification activity and potential therapeutic options.Data SynthesisAortic valve calcification represents the most common heart valve condition requiring treatment among adults in Western societies. No medical therapies are proven to be effective in treating symptoms or reducing disease progression. Therefore, surgical or transcatheter aortic valve replacement remains the only available treatment option. Elevated circulating concentrations of lipoprotein(a) is strongly associated with degenerative aortic stenosis. This relationship was first observed in prospective observational studies, and the causal relationship was confirmed in genetic studies.ConclusionsNew therapeutic targets have been identified and new imaging techniques could be used to test the effectiveness of new agents and further clarify the pathophysiology of AVS. No therapy that specifically lowers Lp (a) levels has been approved for clinical use.  相似文献   
10.
目的 基于网络药理学方法和分子对接技术探究冬虫夏草抗肿瘤的作用机制。方法 利用TCMSP、CNKI、PubMed、Drugbank、Stitch和Swiss target prediction等平台检索冬虫夏草的化学成分和作用靶点;通过GeneCards、OMIM等数据库筛选肿瘤相关基因,运用Cytoscape 3.7.2构建冬虫夏草活性成分-靶点网络,通过String数据库对关键靶点构建网络互作(PPI)网络,并进行基因本体(GO)基因和京都基因和基因组百科全书(KEGG)通路富集分析,最后利用AutoDock Vina软件和Pymol软件对药物有效活性成分和关键靶点进行分子对接验证。结果 共得到冬虫夏草22个化合物,86个抗肿瘤共同靶点,主要包括环加氧酶(PTGS)2、丝裂原活化蛋白激酶3(MAPK3)、过氧化物酶体增生激活受体γ(PPARG)、胱天蛋白酶3(CASP3)、JUN基因等关键靶点。GO分析与KEGG通路结果显示,冬虫夏草抗肿瘤涉及到多种生物学过程以及PPAR、花生四烯代谢、5-羟色胺信号通路等多种信号通路。将关键化合物和靶点进行分子对接,提示冬虫夏草抗肿瘤可能的前5个主要活性成分11,14-二十碳二烯酸、花生四烯酸、黄豆黄素、胆甾醇和豆甾醇与关键靶点PTGS2、PTGS1、PGR、HMGCR和CNR1均能自发结合。结论 初步探讨了冬虫夏草抗肿瘤的主要活性成分、相关靶点及相关通路,发现冬虫夏草可以通过多成分、多靶点、多通路抗肿瘤,为后期实验验证提供了参考依据。  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