全文获取类型
收费全文 | 97993篇 |
免费 | 8615篇 |
国内免费 | 4811篇 |
专业分类
耳鼻咽喉 | 718篇 |
儿科学 | 2075篇 |
妇产科学 | 1637篇 |
基础医学 | 11288篇 |
口腔科学 | 2164篇 |
临床医学 | 9760篇 |
内科学 | 15859篇 |
皮肤病学 | 1414篇 |
神经病学 | 7618篇 |
特种医学 | 1829篇 |
外国民族医学 | 31篇 |
外科学 | 7891篇 |
综合类 | 16715篇 |
现状与发展 | 13篇 |
预防医学 | 8635篇 |
眼科学 | 2853篇 |
药学 | 9311篇 |
31篇 | |
中国医学 | 3488篇 |
肿瘤学 | 8089篇 |
出版年
2024年 | 276篇 |
2023年 | 1209篇 |
2022年 | 2676篇 |
2021年 | 3523篇 |
2020年 | 3142篇 |
2019年 | 2886篇 |
2018年 | 2853篇 |
2017年 | 3259篇 |
2016年 | 3543篇 |
2015年 | 3479篇 |
2014年 | 6160篇 |
2013年 | 6769篇 |
2012年 | 6341篇 |
2011年 | 7005篇 |
2010年 | 5875篇 |
2009年 | 5489篇 |
2008年 | 5713篇 |
2007年 | 5695篇 |
2006年 | 5121篇 |
2005年 | 4540篇 |
2004年 | 3844篇 |
2003年 | 3317篇 |
2002年 | 2749篇 |
2001年 | 2369篇 |
2000年 | 1991篇 |
1999年 | 1711篇 |
1998年 | 1464篇 |
1997年 | 1253篇 |
1996年 | 1128篇 |
1995年 | 1025篇 |
1994年 | 835篇 |
1993年 | 653篇 |
1992年 | 576篇 |
1991年 | 442篇 |
1990年 | 411篇 |
1989年 | 310篇 |
1988年 | 245篇 |
1987年 | 193篇 |
1986年 | 160篇 |
1985年 | 253篇 |
1984年 | 205篇 |
1983年 | 126篇 |
1982年 | 177篇 |
1981年 | 100篇 |
1980年 | 113篇 |
1979年 | 65篇 |
1978年 | 43篇 |
1977年 | 33篇 |
1976年 | 27篇 |
1975年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
KILL AND CURE THE HOPE AND REALITY OF VIRUS INACTIVATION 总被引:2,自引:0,他引:2
CHRISTOPHER PROWSE 《Vox sanguinis》1994,67(S3):191-196
102.
103.
104.
A recent large increase in Caesarean section (CS) in Italy was the initial stimulus for a study to identify risk factors for CS and, if possible, to suggest strategies to counteract the rise. The study was conducted in three hospitals where a wide range of individual variables was collected from the clinical records and from personal interviews. Crude CS rates and odds ratios were evaluated for each single variable while logistic regression has been used to investigate possible confounding factors. The study involved 1316 consecutive deliveries. Crude CS rates were 29.4%, 15.7% and 16.1%. Variables identified as high risk factors were pre-eclampsia, previous CS, breech and other non-vertex presentations. Antenatal care under an obstetrician working in the same hospital, a low number of antenatal consultations, previous miscarriages, offer (by obstetrician) and request (by women) for CS showed significantly high odds ratios (ORs). Previous live births was strongly negatively associated with CS. No relationship between type of delivery and social status was observed while a physician factor was detected in all three hospitals where rates for different physicians ranged from 0% to 52.8%. Apart from the main medical indications for Caesarean section (previous CS, breech presentation), the results seem to indicate that individual practice style may be an important determinant of the wide variation in the rates of Caesarean delivery. While this may have been suspected before this study, these results are the first hard data to indicate that, in Italy, CS is widely performed for non-medical reasons. 相似文献
105.
农村健康保险的精算体系 总被引:5,自引:0,他引:5
本文提出了我国农村健康保险的精算体系和测算保险费、管理费、储备金、预防保健费、保险因子、增加系数、医药费及其补偿比的实用方法。 相似文献
106.
Summary. Platelet membranes provide procoagulant surfaces for the assembly and expression of the factor X-activating complex and promote the proteolytic activation and assembly of the prothrombinase complex resulting in normal hemostasis. Recent studies from our laboratory and others indicate that platelets possess specific, high-affinity, saturable, receptors for factors XI, XIa, IX, IXa, X, VIII, VIIIa, V, Va and Xa, prothrombin, and thrombin. Studies described in this review support the hypothesis that the factor X-activating complex on the platelet surface consists of three receptors (for the enzyme, factor IXa; the substrate, factor X; and the cofactor, factor VIIIa), the colocalization of which results in a 24 million-fold acceleration of the rate of factor X activation. Whether the procoagulant surface of platelets is defined exclusively by procoagulant phospholipids, or whether specific protein receptors exist for the coagulant factors and proteases, is currently unresolved. The interaction between coagulation proteins and platelets is critical to the maintenance of normal hemostasis and is pathogenetically important in human disease. 相似文献
107.
目的研究托吡酯(TPM)对慢性癫痫大鼠海马碱性成纤维细胞生长因子(bFGF)表达的影响。方法制作戊四氮(PTZ)慢性癫痫点燃大鼠模型,分为PTZ组、TPM组及正常对照组,每组又以5d、10d、15d3个时间点各分为3小组。免疫组化法观察各组海马CAl、CA3区及齿状回bFGF表达,HE染色观察病理形态学改变。结果(1)行为学观察:PTZ组和TPM组在癫痫发作上无明显差别。(2)bFGF表达:①各组齿状回区bFGF表达:PTZ组和TPM组各时点表达不断增高,与正常对照组比较差异有统计学意义(均P〈0.01),尤以10d及15d时增高更明显,与5d时比较差异有统计学意义(均P〈0.05)。②各组CAl区bFGF表达:PTZ组各时点均有明显表达,且随时间延长而表达不断增高,各时点比较差异有统计学意义(均P〈0.01),与正常对照组比较差异有统计学意义(均P〈0.01);TPM组在5d时与正常对照组比较差异有统计学意义(P〈0.01),而10d、15d时逐渐下降,接近正常对照组水平。③各组CA3区bFGF表达:5d时3组比较差异无统计学意义。但PTZ组和TPM组在10d时与正常对照组比较差异有统计学意义(P〈0.01),PTZ组在15d时和TPM组及正常对照组比较差异有统计学意义(均P〈0.01)。(3)病理形态学改变:PTZ组和TPM组的海马CAl、CA3区尤其是CAl区可见较多神经元发生变性和坏死,PTZ组更显著。结论PTZ点燃过程中海马bF-GF表达增高,尤其在CAl区,且随时间延长有表达不断增高的趋势。TPM可能通过减少海马神经元损伤而明显下调海马CAl、CA3区bFGF的表达。 相似文献
108.
重度妊娠高血压综合征患者胎盘表皮生长因子受体的表达 总被引:1,自引:1,他引:0
目的:研究胎盘表皮生长因子受体(EGFR)蛋白及基因的表达在置度妊娠高血压综合征(妊高征)发病中的作用以及对妊高征胎儿生长发育的影响。方法:采用免疫组织化学法和逆转录-聚合酶链反应(RT-PCR)技术测定21例重度妊高征患者[分2组,重度妊高征合并胎儿宫内发育迟缓(IUGR)组9例和重度妊高征未合并IUGR组12例]胎盘EGFR的表达,并与15例正常妊娠者(对照组)比较。结果:与对照组相比,重度妊高征患者胎盘EGFR蛋白及其mRNA的表达显著降低(P<0.01),重度妊高征合并EGFR组与重度妊高征未合并IUGR组之间胎盘EGFR的表达差异无显著性(P>0.05)。结论:胎盘滋养层细胞EGFR表达显著降低,可能是重度妊高征发病的重要因素;如果EGFR的低表达发生较早,容易发生IUGR。 相似文献
109.
幕上星形细胞肿瘤MRI表现与VEGF、P16、Ki-67相关性研究 总被引:1,自引:0,他引:1
探讨星形细胞肿瘤MRI表现与P16、Ki—67、血管内皮生长因子(vascular endothelial growth factor,VEGF)表达的相关性。材料和方法:收集我院术前经MRI诊断并经手术病理证实的幕上星形细胞肿瘤53例,行常规平扫描后静脉注射Gd—DTPA增强成像;同时采用HE染色及链菌素生物素—过氧化酶连接法进行VEGF、Ki—67、P16的免疫组织化学染色,测定它们的表达指数。结果:星形细胞肿瘤的信号不均匀性、坏死、水肿、占位效应、强化程度与VEGF、Ki—67、P16的表达相关,且随着星形细胞肿瘤恶性程度的增高VEGF、Ki—67的表达增加;P16的表达率降低。结论:星形细胞肿瘤的MRI表现与VEGF、Ki—67、P16的表达密切相关,MRI可以间接判断星形细胞肿瘤的某些生物学行为。 相似文献
110.
D. E. Aguilar León V. Novelo Retana† E. Martínez-Cordero‡ 《Clinical and experimental allergy》2003,33(2):226-232
BACKGROUND: Although several immunological abnormalities may be present in pigeon hypersensitivity pneumonitis (HP), few specific hallmarks have been described. OBJECTIVE: To determine whether the presence of rheumatoid factor (RF) could be useful to discriminate pigeon HP from asymptomatic breeders (AB) and other interstitial lung diseases. METHODS: Fifty-three patients with pigeon HP, 47 AB, 31 idiopathic pulmonary fibrosis (IPF) patients and a rheumatoid arthritis (RA) group were studied. IgM RF was determined through enzyme-linked immunosorbent assay (ELISA) and western blot using human IgG and IgG Fc fragment as antigens. IgG and IgA anti-avian antibodies (AA) against pigeon serum antigen were also measured. The use of F(ab')2 fraction of peroxidase-labelled anti-human immunoglobulins prevented endogenous interferences. Possible cross-binding of RF with avian antigens and the reactivity against human IgG by AA were studied. RESULTS: RF tests were frequently positive in HP (52.8%) in comparison to AB (4.2%) and IPF (12.9%; P = 2.6 x 10-10 and 4.1 x 10-5). Therefore, the presence of RF in pigeon HP showed a sensitivity of 52% and was highly specific considering the results of AB and IPF (95 and 87%, respectively). The RA group revealed positive RF but negative AA tests. RF activity was confirmed through western blot using purified IgG Fc fragment. Overlapping levels of IgG and IgA AA were found in HP and AB. The frequency of AA was low in IPF. The cross-reaction of RF with avian antigens was excluded, and no reactivity against human IgG by AA was detected. Other endogenous interferences were ruled out. CONCLUSION: No single immunological test may definitively distinguish pigeon HP from AB and other interstitial lung disorders; however, positive RF, together with high AA levels, seems to be useful in differentiating the diagnosis. 相似文献