全文获取类型
收费全文 | 12450篇 |
免费 | 1069篇 |
国内免费 | 439篇 |
专业分类
耳鼻咽喉 | 86篇 |
儿科学 | 155篇 |
妇产科学 | 427篇 |
基础医学 | 1673篇 |
口腔科学 | 219篇 |
临床医学 | 1177篇 |
内科学 | 2025篇 |
皮肤病学 | 100篇 |
神经病学 | 589篇 |
特种医学 | 326篇 |
外国民族医学 | 3篇 |
外科学 | 1645篇 |
综合类 | 1375篇 |
现状与发展 | 3篇 |
预防医学 | 550篇 |
眼科学 | 124篇 |
药学 | 810篇 |
8篇 | |
中国医学 | 332篇 |
肿瘤学 | 2331篇 |
出版年
2024年 | 24篇 |
2023年 | 136篇 |
2022年 | 271篇 |
2021年 | 408篇 |
2020年 | 396篇 |
2019年 | 361篇 |
2018年 | 355篇 |
2017年 | 415篇 |
2016年 | 491篇 |
2015年 | 498篇 |
2014年 | 959篇 |
2013年 | 973篇 |
2012年 | 653篇 |
2011年 | 850篇 |
2010年 | 657篇 |
2009年 | 721篇 |
2008年 | 766篇 |
2007年 | 791篇 |
2006年 | 693篇 |
2005年 | 568篇 |
2004年 | 476篇 |
2003年 | 397篇 |
2002年 | 299篇 |
2001年 | 274篇 |
2000年 | 208篇 |
1999年 | 174篇 |
1998年 | 156篇 |
1997年 | 102篇 |
1996年 | 114篇 |
1995年 | 100篇 |
1994年 | 101篇 |
1993年 | 62篇 |
1992年 | 62篇 |
1991年 | 51篇 |
1990年 | 44篇 |
1989年 | 50篇 |
1988年 | 35篇 |
1987年 | 41篇 |
1986年 | 26篇 |
1985年 | 44篇 |
1984年 | 35篇 |
1983年 | 29篇 |
1982年 | 25篇 |
1981年 | 22篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 562 毫秒
51.
52.
W. Schwizer R. Fraser H. Maecke K. Siebold R. Funck M. Fried 《Magnetic resonance in medicine》1994,31(4):388-393
Current MR meal markers may interfere with gastric motility and secretion restricting the use of MRI in the measurement of gastric physiology. We therefore evaluated Gd-DOTA as a liquid phase marker, in vitro by determining dissociation, and adherence to the solids, and in vivo by simultaneous MRI (0.35 T scanner, multiple T1-weighted sections of the upper abdomen) and double indicator (perfusion marker PEG 4000, meal marker 99mTc-DTPA) measurements of emptying and secretion, following ingestion of 500 ml 10% glucose. In vitro Gd-DOTA was stable at a pH > 2 with < 2% dissociation at 24 h during incubation with HCI. Dissociation during incubation with HCI was linearly dependent on H+ concentration (0.77 < pH < 2.02). Less Gd-DOTA was absorbed onto the solid phase than 99mTc-DTPA (25% cf 36%). in vivo Gd-DOTA marked gastric contents provided strong positive contrast. Similar emptying curves were observed with both MRI and double-indicator techniques (r = 0.987, P < 0.001). Gd-DOTA has the potential to be a useful liquid phase contrast agent in MR studies on gastric function. 相似文献
53.
中期因子在胰腺癌组织中的定位与表达特点 总被引:1,自引:1,他引:0
目的 探讨中期因子(MK)的mRNA及其蛋白在胰腺癌(PC)组织中的定位与表达特点。方法采用原位杂交和免疫组织化学方法检测52例PC、12例慢性胰腺炎及6例正常胰腺组织中MK mRNA及蛋白的定位与表达水平。结果MK mRNA及蛋白水平在PC组织均呈过度表达,表达阳性率分别为71.2%和73.1%,都定位于PC细胞质,有淋巴结转移和Ⅱ-Ⅳ期的患者,MK阳性表达率明显高于无淋巴结转移和Ⅰ期患者(P<0.01)。在PC细胞外组织中也有MK表达,尤其在血管密集处明显。而在慢性胰腺炎及正常胰腺组织中MK表达阴性。结论 MK mR-NA及其蛋白在PC组织中呈过度表达,并可能与促进PC血管生成和转移有关。检测MK表达情况可作为PC的辅助诊断指标之一。 相似文献
54.
环氧合酶-2和血管内皮生长因子共表达与肝细胞癌血管形成的关系 总被引:7,自引:6,他引:1
目的 探讨环氧合酶 (COX) 2与肝细胞癌血管形成的关系。方法 利用免疫组织化学、Westernblot方法检测 48例肝癌组织中COX 2和血管内皮生长因子 (VEGF)蛋白及逆转录 聚合酶链反应法 (RT PCR)检测COX 2和VEGFmRNA的共表达 ,对共表达COX 2和VEGF蛋白和mRNA的肝癌组织进行微血管记数。结果 免疫组织化学检测中 ,48例肝癌组织 3 6例共表达COX 2和VEGF蛋白。类似结果见于蛋白电泳分析。RT PCR显示 ,48例肝癌组织 3 6例共表达COX 2mRNA和VEGFmRNA。两者之间的表达明显相关 (γ =0 .845 )。共表达COX 2和VEGF蛋白和mRNA的肝癌组织中 ,平均微血管数 (5 6.8± 17.5 )个 ,明显高于阴性表达组。结论 COX 2可能与肝细胞癌的血管形成有关 ,且其作用之一可能是通过上调VEGF通道来发挥的 相似文献
55.
功能性便秘患儿胃肠传输时间的测定 总被引:1,自引:0,他引:1
目的 :采用不透X线标志物测定功能性便秘患儿和正常儿童全胃肠传输时间口 盲传输时间 ,结肠传输时间及分段结肠传输时间的正常值 .方法 :通过口服不透X线标志物 ,用X线拍片法分别于 12 ,2 4和 4 8h摄腹部平片 ,测定 6 8名正常儿童全胃肠传输时间 (totalgastrointestinaltransittime,TGITT)、口 盲时间 (mouth intestinetransittime ,M ITT)和结肠传输时间 (colonictransittime ,CTT) .结果 :正常儿童及FC患儿的 5 0 %全胃肠、口 盲、全结肠传输时间分别为 (2 3.6± 1.6 )h ,(9.9± 1.4 )h ,(14 .8± 1.8)和 (80 .4± 2 .1)h ,(2 0 .7± 0 .6 )h ,(5 9.9± 2 .3)h .节段性结肠传输时间包括 :右半结肠传输时间 (rightcolonictransittime,RCTT) ;左半结肠传输时间 (leftcolonictransittime ,LCTT)和直肠乙状结肠传输时间 (rectosigmoidcolonictransittime,RSTT)分别为 (7.3± 1.1)h ,(3.4± 0 .8)h ,(4 .1± 1.2 )和 (2 0 .3± 1.2 )h ,(12 .8± 1.7)h ,(2 6 .8± 1.4 )h .结论 :正常儿童胃肠传输时间与正常成人和功能性便秘患儿比较有显著差异 (P <0 .0 1) .胃肠传输时间测定可了解全胃肠及各段的动力情况 ,对功能性便秘的诊断及评估治疗效果有实用意义 相似文献
56.
T. WROBEL G. MAZUR D. WOLOWIEC B. JAZWIEC E. SOWINSKA K. KULICZKOWSKI 《International journal of laboratory hematology》2006,28(1):36-39
The role of angiogenesis in multiple myeloma (MM) pathogenesis is well established. Angiogenesis is linked to the functional state of endothelial junctions that are modulated by the growth and activation of endothelial cells. CD146 and vascular endothelial‐cadherin (VE‐cadherin) are cell adhesion molecules localized at the endothelial junction. The aim of the study was to assess sVE‐cadherin and sCD146 serum levels in MM patients. Forty‐six untreated patients with MM were included in this study. In addition, 23 of 46 patients were analyzed again in partial remission after initial chemotherapy. Twenty‐two samples from healthy volunteers were evaluated as the control. There was no significant difference in sCD146 level between MM patients and the control (511 ± 177.2 vs. 460.9 ± 156.9 ng/ml respectively). In untreated MM patients, sVE‐cadherin level was significantly higher than in the control (1.36 ± 0.55 vs. 0.63 ± 0.56 ng/ml respectively; P < 0.05). In untreated MM patients, sVE‐cadherin level was significantly higher than in MM patients in partial remission (1.36 ± 0.55 vs. 0.5 ± 0.33 respectively; P < 0.05). sVE‐cadherin but not sCD146 serum level was increased in untreated MM patients and decreases after chemotherapy in patients in partial remission. VE‐cadherin may reflect intensity of angiogenesis in MM and may be useful in prognosis of response to treatment. 相似文献
57.
MMP-2、TIMP-2、VEGF和bFGF在血管瘤增生及消退过程中的变化 总被引:1,自引:0,他引:1
目的 探讨基质金属蛋白酶-2(MMP-2)及其抑制剂(TIMP-2)、血管内皮生长因子(VEGF)和碱性成纤维细胞生长因子(bFGF)在血管瘤增生、消退过程中的变化。方法 采用免疫组织化学链霉亲和素-过氧化酶(SP)法,检测增生期血管瘤32例、消退期血管瘤10例、血管畸形17例及小儿正常皮肤10例标本中MMP-2、TIMP-2、VEGF及bFGF的表达。结果 MMP-2、VEGF及bFGF在增生期血管瘤中的表达明显高于消退期血管瘤、血管畸形和正常皮肤,其差异有统计学意义;TIMP-2在消退期血管瘤中的表达明显高于增生期血管瘤、血管畸形和正常皮肤,其差异有统计学意义。结论 MMP-2、VEGF及bFGF可能促进血管瘤血管生成,从而促进血管瘤增生,而TIMP-2可能促进血管瘤消退。 相似文献
58.
59.
Cristina Antúnez María Jose Torres Cristobalina Mayorga José L. Corzo Antonio Jurado Luis F. Santamaría-Babi Angel Vera Miguel Blanca 《Pediatric allergy and immunology》2006,17(3):166-174
T cells are known to develop a critical role in the pathogenesis of atopic dermatitis (AD) and bronchial asthma. T cells involved in AD express the skin homing receptor CLA, but no lung homing receptor has been identified in bronchial asthma. We compared different cell markers and the cytokine production in T cells from children with AD or bronchial asthma. We studied the involvement of CLA+ and CLA- T-cell subpopulations in these diseases. We studied 20 children with acute AD lesions, 15 with mild persistent asthma, and 15 non-atopic controls. All patients were sensitized to house dust mite (DP) and evaluated during the acute phase. Total and specific IgE were measured by immunoassay and the expression of different cell markers and the cytokine production was analyzed by flow cytometry in peripheral blood mononuclear cells. Total IgE was significantly higher in AD children and IgE to DP in the asthmatic children. There was a significant increase in CD25+ CD4+ cells in asthmatic children and in HLA-DR+ CD4+ and HLA-DR+ CD8+ cells in AD. In the CD4+ subsets, there was an increase in IL-13, IL-5 and TNF-alpha in AD compared to controls, a decrease in IFN-gamma in asthmatic children compared to controls, and an increase in IL-13, IL5, IL2, TNF-alpha, and IFN-gamma in the AD compared to asthmatic children. Changes in cytokine production were mainly detected in CLA+ cells in AD and in CLA- cells in asthma. Differences exist in total and specific IgE, activation markers, and cytokine patterns between AD children and children with asthma, with the former expressing a Th2 pattern whereas in asthmatic children we only detected a decrease in IFN-gamma. Moreover, the subpopulations (CLA+ vs. CLA-) expressing these changes were different, indicating that the underlying mechanisms in the two diseases are not exactly the same. 相似文献
60.
TNP-470对裸鼠体内人结肠癌细胞增殖和凋亡的影响 总被引:1,自引:0,他引:1
目的 研究TNP-470对裸鼠体内人结肠癌细胞增殖和凋亡的影响。方法 将16只人结肠癌皮下移植瘤裸鼠随机分成实验组和对照组,实验组隔日予以TNP-47030mg/kg,皮下注射,对照组予以相同体积的生理盐水,4周后处死,应用免疫组织化学法(免疫组化)和图象分析技术检测肿瘤细胞中增殖细胞核抗原(PCNA)的表达,TdT介导的dUTP缺口末端标记(TUNEL)法检测肿瘤细胞的凋亡,透射电镜观察凋亡细胞的超微结构。结果 TNP-470明显抑制了肿瘤的生长,抑瘤率为45.53%。实验组肿瘤中PCNA的表达显低于对照组,凋亡指数上升,电镜下可见典型的细胞凋亡形态学变化。结论 TNP-470除了通过抗血管生成作用抑制肿瘤生长外,还可通过抑制LOVO细胞本身的增殖和诱导凋亡发挥抗肿瘤作用。 相似文献