全文获取类型
收费全文 | 29080篇 |
免费 | 2768篇 |
国内免费 | 2326篇 |
专业分类
耳鼻咽喉 | 205篇 |
儿科学 | 353篇 |
妇产科学 | 321篇 |
基础医学 | 3777篇 |
口腔科学 | 491篇 |
临床医学 | 4005篇 |
内科学 | 4738篇 |
皮肤病学 | 269篇 |
神经病学 | 1451篇 |
特种医学 | 1286篇 |
外国民族医学 | 21篇 |
外科学 | 2958篇 |
综合类 | 4440篇 |
现状与发展 | 9篇 |
一般理论 | 4篇 |
预防医学 | 1745篇 |
眼科学 | 718篇 |
药学 | 2917篇 |
31篇 | |
中国医学 | 1491篇 |
肿瘤学 | 2944篇 |
出版年
2024年 | 108篇 |
2023年 | 497篇 |
2022年 | 1279篇 |
2021年 | 1637篇 |
2020年 | 1222篇 |
2019年 | 967篇 |
2018年 | 1072篇 |
2017年 | 913篇 |
2016年 | 878篇 |
2015年 | 1380篇 |
2014年 | 1695篇 |
2013年 | 1343篇 |
2012年 | 2017篇 |
2011年 | 2254篇 |
2010年 | 1383篇 |
2009年 | 1105篇 |
2008年 | 1416篇 |
2007年 | 1525篇 |
2006年 | 1397篇 |
2005年 | 1538篇 |
2004年 | 902篇 |
2003年 | 808篇 |
2002年 | 751篇 |
2001年 | 632篇 |
2000年 | 626篇 |
1999年 | 702篇 |
1998年 | 582篇 |
1997年 | 539篇 |
1996年 | 444篇 |
1995年 | 421篇 |
1994年 | 320篇 |
1993年 | 198篇 |
1992年 | 241篇 |
1991年 | 185篇 |
1990年 | 160篇 |
1989年 | 169篇 |
1988年 | 186篇 |
1987年 | 124篇 |
1986年 | 122篇 |
1985年 | 114篇 |
1984年 | 59篇 |
1983年 | 46篇 |
1982年 | 53篇 |
1981年 | 35篇 |
1980年 | 34篇 |
1979年 | 22篇 |
1978年 | 9篇 |
1977年 | 16篇 |
1976年 | 16篇 |
1975年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
目的分析超声介入医师行实时影像虚拟导航系统(RVS)辅助肝癌消融的学习曲线。 方法回顾性分析2018年10月至2019年9月就诊于浙江中医药大学附属杭州市西溪医院的,由同一名具有5年以上超声引导下肝癌消融经验的医师,行RVS引导下辅助肝癌消融的第1~60例肝癌患者资料。按照治疗顺序分为A、B、C组,每组各20例。采用方差分析比较各组间RVS术前融合时间和肿瘤消融时间的差异,组间两两比较采用LSD-t检验;采用Fisher确切概率法分析患者组间肿瘤1次性消融成功率和术后1个月肿瘤的完全灭活率的差异。绘制RVS辅助肝癌消融的术前融合时间曲线图。 结果A组的RVS术前融合时间、肿瘤消融时间明显大于B组及C组[(20.9±6.7)min vs (9.7±1.2)min vs (9.6±2.7)min;(23.1±7.9)min vs (19.6±5.0)min vs (19.2±3.7)min],差异具有统计学意义(t=7.4,P<0.001;t=1.9,P=0.035),B组与C组之间比较,差异均无统计学意义(P均>0.05);A组的肿瘤1次性消融成功率[74.1%(20/27)]小于B组[96.4%(27/28)]和C组[96.4%(27/28)],差异具有统计学意义(P均=0.025),B组与C组之间比较,差异无统计学意义(P>0.05)。3组RVS辅助肝癌消融术后1个月肿瘤完全灭活率比较[92.6%(25/27) vs 92.9%(26/28) vs 92.9%(26/28)],差异均无统计学意义(P均>0.05)。操作者积累约20例患者后,术前融合时间趋于稳定,学习进入平台期。 结论对于期望熟练掌握RVS辅助肝癌消融的介入医师,操作者积累约20例患者RVS辅助肝癌消融可以明显缩短术前融合时间和肿瘤消融时间,提高融合精准度、团队契合度及肿瘤1次性消融成功率,之后学习曲线进入平台期。 相似文献
992.
Petri M. Leukkunen Ekta Rani Assa Aravindh Sasikala Devi Harishchandra Singh Graham King Matti Alatalo Wei Cao Marko Huttula 《RSC advances》2020,10(60):36930
P25 comprising of mixed anatase and rutile phases is known to be highly photocatalytically active compared to the individual phases. Using a facile wet chemical method, we demonstrate a ternary nanocomposite consisting of Ni and Ag nanoparticles, decorated on the surface of XTiO2 (X: P25, rutile (R)) as an efficient visible-light-driven photocatalyst. Contrary to the current perspective, RTiO2-based Ni–Ag–RTiO2 shows the highest activity with the H2 evolution rate of ∼86 μmol g−1 W−1 h−1@535 nm. Together with quantitative assessment of active Ni, Ag and XTiO2 in these ternary systems using high energy synchrotron X-ray diffraction, transmission electron microscopy coupled energy dispersive spectroscopy mapping evidences the metal to semiconductor contact via Ag. The robust photocatalytic activity is attributed to the improved visible light absorption, as noted by the observed band edge of ∼2.67 eV corroborating well with the occurrence of Ti3+ in Ti 2p XPS. The effective charge separation due to intimate contact between Ni and RTiO2via Ag is further evidenced by the plasmon loss peak in Ag 3d XPS. Moreover, density functional theory calculations revealed enhanced adsorption of H2 on Ti8O16 clusters when both Ag and Ni are simultaneously present, owing to the hybridization of the metal atoms with d orbitals of Ti and p orbitals of O leading to enhanced bonding characteristics, as substantiated by the density of states. Additionally, the variation in the electronegativity in Bader charge analysis indicates the possibility of hydrogen evolution at the Ni sites, in agreement with the experimental observations.Robust photocatalytic activity of Ni–Ag–RTiO2 is attributed to the improved visible light absorption and effective charge separation due to intimate contact between Ni and RTiO2via Ag, as evidenced by Ti3+ in Ti 2p XPS and energy dispersive mapping. 相似文献
993.
Zhimin Dong Zhibin Zhang Runze Zhou Yayu Dong Yuanyuan Wei Zhijian Zheng Youqun Wang Ying Dai Xiaohong Cao Yunhai Liu 《RSC advances》2020,10(57):34859
In this work, nitrogen and phosphorus co-doped magnetic carbon spheres encapsulating well-dispersed active Fe nanocrystals (Fe/P-CN) were fabricated via a simple copolymer pyrolysis strategy. Benefiting from heteroatoms doping, Fe/P-CN could primarily adsorb soluble U(vi) ions through abundant functional groups, and subsequently, the adsorbed U(vi) could be reduced to insoluble U(iv) by Fe nanocrystals. Fe/P-CN pyrolyzed at 800 °C (Fe/P-CN-800) exhibited excellent U(vi) removal capacity of 306.76 mg g−1, surpassing nitrogen and phosphorus co-doped carbon spheres and nano zero-valent iron. In addition, the magnetic separation and thermal reactivation properties endow Fe/P-CN-800 with excellent reusability. This research, especially, provides a promising synergistic adsorption and reduction strategy to effectively remove U(vi) using heteroatom-doped composites.The constructed novel magnetic carbon sphere co-doped by N, P, Fe (Fe/P-CN) exhibits high U(vi) removal efficiency, excellent magnetic separation and reusability, evidencing the potential practical applications in environmental remediation. 相似文献
994.
Jing Zhang Shui Hu Yi Du Ding Cao Guirong Wang Zhiqin Yuan 《Yao wu shi pin fen xi = Journal of food and drug analysis.》2020,28(4):622
Improper use of food additives may lead to potential threat to human health, making it important to develop sensitive and selective method for their detection. Nanomaterials with unique chemical and electrochemical properties show extensive applications in the design of food additive sensing systems. In this review, we summarize the recently adopted electrochemical and optical analysis of food additives based on nanomaterials. Detection of typical food additives (colorants and preservatives) by using different sensing mechanisms and strategies are provided. In addition, determination of illegal food additives is also briefly introduced. Finally, this review highlights the challenges and future trend of nanomaterial-based food analysis system. 相似文献
995.
Xiangyu Cao Siqi Tian Mingyang Fu Yanmei Li Yueling Sun Jianli Liu Yue Liu 《Environmental toxicology》2020,35(5):609-618
Nickel is a common environmental pollutant that can impair the lung, but the underlying mechanisms have not yet been fully elucidated. Furthermore, natural products are generally used to inhibit cell damage induced by heavy metal. Resveratrol possesses wide biological activities, including anti‐inflammation and antioxidative stress. This study was conducted to explore the toxicity of nickel on human bronchial epithelial (BEAS‐2B) cells and evaluate the protective effect of resveratrol. The results showed that nickel could induce cell apoptosis, increase oxidative stress, and promote the expression of pro‐inflammatory cytokines, including tumor necrosis factor‐α, interleukin (IL)‐1β, IL‐6, IL‐8, C‐reaction protein. Western blot analysis showed that nickel activated p38 mitogen‐activated protein kinase (MAPK), nuclear factor‐kappa B, and nucleotide‐binding oligomerization domain‐like receptor pyrin‐domain‐containing protein 3 pathways, while resveratrol could reverse these effects. Our results suggested that resveratrol could protect BEAS‐2B cells from nickel‐induced cytotoxicity. Therefore, resveratrol is a potential chemopreventive agent against nickel‐induced lung disease. 相似文献
996.
目的 探索腹盆腔放疗照射对肠道微生态的影响及其与肠源性感染的关系。方法 模拟腹盆腔放疗照射BALB/c小鼠,2.0 Gy/d,连续照射5 d/周,分别于照射3周、5周和6周后停照1周的时间点收集回肠组织及其内容物样本。用实时定量RT-PCR检测抗菌肽和促炎性因子的表达;用PCR检测细菌在小鼠体内的移位情况;用变性梯度凝胶电泳技术检测分析肠道微生态的特征。结果 腹盆腔照射诱发了肠道潘氏细胞隐窝素-1和-4表达紊乱,照射3周或照射6周后停照1周,小鼠回肠隐窝素-1和-4均呈现显著性降低(t=-7.43、-3.54、-4.72、-4.27,P<0.05);而照射5周小鼠回肠隐窝素-1和-4表达明显升高(t=6.15、5.75,P<0.05)。放疗模拟照射3和5周时小鼠肠道微生物区系多样性指数和丰富度显著降低(t=-3.49、-4.19、-3.44、-4.97,P<0.05),呈现以乳酸杆菌等益生菌减少,大肠杆菌和弗氏志贺氏菌等条件致病菌增多为特征的微生态失调。受照小鼠肠系膜淋巴结和血液中的细菌DNA阳性率明显增高。照射3和5周后回肠组织IL-1β、IL-6和TNF-α显著性高表达(t=4.85、6.16、7.71、4.60、4.86、5.97,P<0.05);照射6周后停照1周时,肠道促炎性因子的表达量有所回落,但IL-1β和TNF-α的表达量仍显著性高表达(t=3.67、5.88,P<0.05)。结论 腹盆腔放疗可诱发肠道抗菌肽表达紊乱,引起肠道微生态失调,进而导致肠源性细菌移位及感染性炎症的发生。微生态可能成为减轻放疗患者消化道不良反应的有效干预靶点。 相似文献
997.
998.
999.
目的探讨2型糖尿病(T2DM)患者血清胰岛素样生长因子-1(IGF-1)水平与双侧颈动脉粥样硬化斑块的相关性。方法应用超声检测186例患者双侧颈动脉内膜-中膜厚度,根据超声检查结果将其分为:(1)A组(颈动脉粥样硬化斑块阳性的T2DM患者)96例;(2)B组(颈动脉粥样硬化斑块阴性的T2DM患者)90例。并采用免疫放射分析法检测两组患者的血清IGF-1水平。结果 A组患者的血清IGF-1水平与B组比较显著降低,差异有显著统计学意义(P<0.01);T2DM患者血清IGF-1水平与双侧颈动脉粥样斑块的程度呈显著负相关(r=0.649,P<0.01)。结论 IGF-1参与了T2DM大血管病变的发生、发展,IGF-1水平与颈动脉粥样斑块程度密切相关。 相似文献
1000.
Heather-Marie P. Wilson Robert E. Welikson Jun Luo Thomas J. Kean Baohong Cao James E. Dennis Margaret D. Allen 《Clinical orthopaedics and related research》2015,473(9):2908-2919