全文获取类型
收费全文 | 63242篇 |
免费 | 6680篇 |
国内免费 | 4793篇 |
专业分类
耳鼻咽喉 | 492篇 |
儿科学 | 611篇 |
妇产科学 | 598篇 |
基础医学 | 7407篇 |
口腔科学 | 1217篇 |
临床医学 | 8487篇 |
内科学 | 9936篇 |
皮肤病学 | 614篇 |
神经病学 | 3555篇 |
特种医学 | 2249篇 |
外国民族医学 | 52篇 |
外科学 | 6438篇 |
综合类 | 11144篇 |
现状与发展 | 19篇 |
一般理论 | 5篇 |
预防医学 | 4430篇 |
眼科学 | 1872篇 |
药学 | 6894篇 |
39篇 | |
中国医学 | 3432篇 |
肿瘤学 | 5224篇 |
出版年
2024年 | 266篇 |
2023年 | 1174篇 |
2022年 | 2728篇 |
2021年 | 3413篇 |
2020年 | 2605篇 |
2019年 | 2242篇 |
2018年 | 2254篇 |
2017年 | 2088篇 |
2016年 | 1977篇 |
2015年 | 2979篇 |
2014年 | 3700篇 |
2013年 | 3162篇 |
2012年 | 4894篇 |
2011年 | 5274篇 |
2010年 | 3134篇 |
2009年 | 2421篇 |
2008年 | 3345篇 |
2007年 | 3211篇 |
2006年 | 3162篇 |
2005年 | 3114篇 |
2004年 | 2031篇 |
2003年 | 1974篇 |
2002年 | 1630篇 |
2001年 | 1393篇 |
2000年 | 1430篇 |
1999年 | 1638篇 |
1998年 | 999篇 |
1997年 | 966篇 |
1996年 | 699篇 |
1995年 | 643篇 |
1994年 | 644篇 |
1993年 | 394篇 |
1992年 | 564篇 |
1991年 | 426篇 |
1990年 | 389篇 |
1989年 | 326篇 |
1988年 | 318篇 |
1987年 | 257篇 |
1986年 | 217篇 |
1985年 | 181篇 |
1984年 | 98篇 |
1983年 | 60篇 |
1982年 | 45篇 |
1981年 | 41篇 |
1980年 | 19篇 |
1979年 | 42篇 |
1978年 | 15篇 |
1977年 | 14篇 |
1964年 | 7篇 |
1936年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
目的 研究基于英国国家早期预警评分(NEWS)构建的防控管理模型在致命性出血介入治疗患者中的应用效果。方法 选取2019年6月至2020年6月湖南省某三甲医院收治的200例致命性出血介入治疗患者作为研究对象,将其随机分为观察组(n=100)和对照组(n=100)。对照组实施常规干预措施及流程,观察组在对照组基础上实施基于NEWS评分的防控管理,比较两组患者介入治疗急救时长、并发症发生率、死亡率和休克分期等情况。结果 观察组患者的预检分诊时间、多学科小组接诊时间、入院至B超出报告时间、入院至实验室出报告时间、急诊滞留时间、入院至到达手术室时间短于对照组,差异有统计学意义(P <0.05)。观察组患者多器官功能障碍综合征(MODS)、感染、心跳骤停等并发症发生率和死亡率低于对照组,差异有统计学意义(P <0.05)。观察组患者术后4 h休克分期情况优于对照组,差异有统计学意义(P <0.05)。结论 基于NEWS评分的致命性出血防控管理模型有助于临床医护人员早期识别致命性出血的风险,通过评分值采取相应的急救防控措施能显著缩短介入治疗患者的急救时长,降低术后并发症的发生率及... 相似文献
953.
To improve the flexural properties of cemented soils reinforced with fibers and avoid their brittle failure when subjected to complex loading conditions, a simple and cost-effective technique was explored to facilitate their application in retaining walls. In this study, how different fiber surface modifications, i.e., alkali treatment, acid treatment and silane coupling agent treatment, as well as different fiber contents, i.e., 0%, 0.25%, 0.5% and 1%, affect the bending properties of cemented soils was investigated by conducting three-point bending tests on notched beams. The digital image correlation (DIC) technology was used to examine the crack propagation process and the strain field distribution of cracks in specimens in the flexural tests. The results show that all fiber surface modifications increased peak strength and fracture energy, for example, the fracture energy of specimens AN1, AH1 and AK1 was increased by 180.4%, 121.5% and 155.4%, respectively, compared to PVA1. In addition, the crack tip strain, crack propagation rate and the initial crack width of the modified specimens were lower than those before modification. Lastly, scanning electron microscope (SEM) and mercury intrusion porosimetry tests were adopted to reveal the mechanism of bending performance in cemented soils reinforced by fiber surface modifications. 相似文献
954.
955.
Jianian Hu Ye Tan Xuemei Li Youlin Zhu Guoqiang Luo Jian Zhang Ruizhi Zhang Yi Sun Qiang Shen Lianmeng Zhang 《Materials》2022,15(14)
With the need of developing new materials, exploring new phenomenon, and discovering new mechanisms under extreme conditions, the response of materials to high-pressure compression attract more attention. However, the high-pressure state deviating from the Hugoniot line is difficult to realize by conventional experiments. Gas gun launching graded materials could reach the state. In our work, the corresponding Al-Cu composites and graded materials are prepared by tape casting and hot-pressing sintering. The microstructure and the acoustic impedance of the corresponding Al-Cu composites are analyzed to explain the impact behavior of Al-Cu graded materials. Computed tomographic testing and three-dimension surface profilometry machine results demonstrated well-graded structure and parallelism of the graded material. Al-Cu GMs with good parallelism are used to impact the Al-LiF target at 2.3 km/s using a two-stage light-gas gun, with an initial shock impact of 20.6 GPa and ramping until 27.2 GPa, deviating from the Hugoniot line. 相似文献
956.
Dongtong Yang Sen Tang Yongtao Hu Alexander Nikitin Qingyuan Wang Yongjie Liu Lang Li Chao He Yan Li Bo Xu Chong Wang 《Materials》2022,15(14)
The very high cycle fatigue (VHCF) failure of in-service components is mainly caused by the vibration of thin-wall elements at a high frequency. In this work, a novel model of ultrasonic fatigue test was developed to test thin-wall material in bending up to VHCF with an accelerated frequency. The theoretical principle and finite element analysis were introduced for designing a sample that resonated at the frequency of 20 kHz in flexural vibration. In the advantage of the second-order flexural vibration, the gauge section of the sample was in the pure bending condition which prevented the intricate stress condition for thin-wall material as in the root of cantilever or the contact point of three points bending. Moreover, combining the constraint and the loading contact in one small section significantly reduced heating that originated from the friction at an ultrasonic frequency. Both strain gauge and deflection angle methods were applied to verify the controlling of stress amplitude. The fractography observation on Ti6Al4V samples indicated that the characterized fracture obtained from the novel model was the same as that from the conventional bending test. 相似文献
957.
Zheng Chen Xifeng Hu Xiangdong Wu Yu Li Zhen Ding Qinghua Zeng Tong Wan Jingyi Yin Huansheng Wu 《Viruses》2022,14(7)
Porcine circovirus-like virus (PCLV) is a member of circovirus that contains a single-strand DNA genome, which may be one of the pathogens that causes diarrheal symptoms in pigs. The Rep protein encoded by the genome of PCLV may be responsible for viral genome replication. The development of serological detection methods for PCLV is of great necessity for clinical diagnosis, as well as epidemiological investigations. Therefore, this study attempted to build an indirect enzyme-linked immunosorbent assay (ELISA) to examine antibodies against PCLV based on the His-tagged recombinant Rep protein. Full-length PCLV Rep protein was induced and expressed in E. coli and was purified as an antigen to establish an ELISA detection kit. The purified Rep protein was used to inject into mice to produce specific antibodies. There was no cross-reaction of Rep-based ELISA with antisera against other porcine viruses. The intra-assay and inter-assay coefficient variations (CVs) were 0.644–8.211% and 0.859–7.246%, respectively, indicating good repeatability. The non-cross-reaction with TGEV, PRRSV and PCV2 testing showed high sensitivity and high specificity for this ELISA assay. A total of 1593 serum samples collected from different pig farms in Jiangxi Province were tested for anti-PCLV Rep antibodies, and 284 (17.83%) of the 1593 samples were Rep antibody positive. Altogether, the indirect ELISA detection tool developed in this study could be applied to examine serum of PCLV antibodies with good repeatability, high sensitivity and high specificity. In addition, field sample detection results suggested that the PCLV antibody has a low prevalence in pig populations in Jiangxi Province of China. 相似文献
958.
目的研究培哚普利对阵发性心房颤动(PAF)导管射频消融术患者血清可溶型基质裂解素2(sST2)、半乳糖凝聚素3(galectin-3)水平的影响。方法选取2018年1月至2020年1月重庆医科大学附属第三医院收治的112例PAF导管射频消融术患者,随机数字表法分为试验组(培哚普利联合常规治疗方案)和对照组(常规治疗方案)各56例。比较两组治疗前及治疗3个月后心功能指标[左心房内径(LAD)、左室射血分数(LVEF)]、炎症因子[超敏C反应蛋白(hs-CRP)、血管紧张素Ⅱ(AngⅡ)]和疾病相关因子(sST2、galectin-3),比较两组复发情况及不良反应发生情况。结果治疗3个月后,试验组LAD、hs-CRP、AngⅡ、sST2、galectin-3水平明显低于治疗前及同期对照组,LVEF水平明显高于治疗前及同期对照组(P<0.05)。试验组早、晚期复发率均明显低于对照组(P<0.05)。两组恶心、呕吐、咳嗽、心脏压塞发生情况比较,差异无统计学意义(P>0.05)。结论培哚普利能够改善PAF导管射频消融术患者心功能,降低血清炎性因子、疾病相关因子水平及术后复发率。 相似文献
959.
960.
混合探针底物法测定五味子成分对大鼠肝脏细胞色素P450同工酶的影响 总被引:2,自引:0,他引:2
研究大鼠多次口服五味子成分和体外对肝脏细胞色素P450酶(CYP450)6种同工酶的影响。采用超速离心法制备正常及多次口服五味子醇/水提物的大鼠肝微粒体并与探针药进行体外温孵,应用液相色谱?串联质谱分析方法测定CYP450的6种同工酶特异性探针底物非那西丁(CYP1A2)、右美沙芬(CYP2D2)、双氯芬酸钠(CYP2C6)、美芬妥英(CYP2C11)、氯唑沙宗(CYP2E1)、咪达唑仑(CYP3A1/2)在大鼠肝微粒体的代谢产物生成(对乙酰氨基酚、右啡烷、4-羟基双氯芬酸钠、4-羟基美芬妥英、6-羟基氯唑沙宗、1-羟基咪达唑仑)以反映各CYP450同工酶活性。五味子醇提物(28~120μg.mL-1)体外对大鼠肝微粒体CYP450的6个同工酶均有不同程度的抑制作用。大鼠多次口服五味子醇提物(1.5 g.kg-1,qd×7d)对肝脏CYP3A1/2和CYP2E1有显著诱导作用,对CYP2D2和CYP2C11有明显抑制作用,而对CYP2C6和CYP1A2无明显影响。五味子水提物(100~500μg.mL-1)体外对大鼠肝脏CYP450同工酶亦有抑制作用;体内多次给药(1.5 g.kg-1,qd×7d)对肝脏CY... 相似文献