全文获取类型
收费全文 | 428篇 |
免费 | 48篇 |
国内免费 | 3篇 |
学科分类
医药卫生 | 479篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 8篇 |
2015年 | 12篇 |
2014年 | 34篇 |
2013年 | 19篇 |
2012年 | 25篇 |
2011年 | 30篇 |
2010年 | 27篇 |
2009年 | 22篇 |
2008年 | 24篇 |
2007年 | 15篇 |
2006年 | 23篇 |
2005年 | 27篇 |
2004年 | 24篇 |
2003年 | 21篇 |
2002年 | 16篇 |
2001年 | 16篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有479条查询结果,搜索用时 31 毫秒
1.
Ofer Shamni Bruno Nebeling Hilbert Grievink Eyal Mishani 《Journal of labelled compounds & radiopharmaceuticals》2019,62(6):252-258
Radiolabeled prostate‐specific membrane antigen (PSMA) targeting PET‐tracers have become desirable radiopharmaceuticals for the imaging of prostate cancer (PC). Recently, the PET radiotracer [18F]PSMA‐1007 was introduced as an alternative to [68Ga]Ga‐PSMA‐11, for staging and diagnosing biochemically recurrent PC. We incorporated a one‐step procedure for [18F]PSMA‐1007 radiosynthesis, using both Synthra RNplus and GE TRACERlab FxFN automated modules, in accordance with the recently described radiolabeling procedure. Although the adapted [18F]PSMA‐1007 synthesis resulted in repeatable radiochemical yields (55 ± 5%, NDC), suboptimal radiochemical purities of 87 ± 8% were obtained using both modules. As described here, modifications made to the radiolabeling and the solid‐phase extraction purification steps reduced synthesis time to 32 minutes and improved radiochemical purity to 96.10%, using both modules, without shearing the radiochemical yield. 相似文献
2.
目的 优化18F-FHBG的合成方法,并评估合成18F-FHBG的质量稳定性。方法 自行设计18F-FHBG自动化合成流程,待前体N2-(对甲氧苯基二苯基甲基)-9-[(4-甲苯磺酰基)-3-对甲氧苯基二苯基甲氧基-甲基丁基]鸟嘌呤与18F-发生亲核取代反应后,经洗脱、纯化获得18F-FHBG。记录合成时间,评估合成效率,测定产品放射化学纯度及其体外稳定性,观察其生物分布及PET/CT显像特征。结果 18F-FHBG的合成时间为19~25 min,未校正合成效率为(19.00±5.00)%(n>10);室温放置5、30、60、90、120 min及6 h后,放射化学纯度均>97%。生物分布实验结果显示,18F-FHBG主要分布于正常昆明小鼠的肝脏、胃肠道及肾脏,脑组织内摄取较少。PET/CT显像结果显示,对新西兰大白兔注射18F-FHBG后,放射性分布遍及全身较快,注射60 min时显像效果较好。结论 优化的全自动合成方法能快速、高效合成纯度高、稳定性好的18F-FHBG,适用于PET/CT全身显像。 相似文献
3.
Emeline Darot Jrme Yerly Tom Hilbert Roberto Colotti Elena Najdenovska Tobias Kober Matthias Stuber Ruud B. van Heeswijk 《NMR in biomedicine》2021,34(1)
Fluorine‐19 (19F) MRI of injected perfluorocarbon emulsions (PFCs) allows for the non‐invasive quantification of inflammation and cell tracking, but suffers from a low signal‐to‐noise ratio and extended scan time. To address this limitation, we tested the hypotheses that a 19F MRI pulse sequence that combines a specific undersampling regime with signal averaging has both increased sensitivity and robustness against motion artifacts compared with a non‐averaged fully sampled pulse sequence, when both datasets are reconstructed with compressed sensing. As a proof of principle, numerical simulations and phantom experiments were performed on selected variable ranges to characterize the point spread function of undersampling patterns, as well as the vulnerability to noise of undersampling and reconstruction parameters with paired numbers of x signal averages and acceleration factor x (NAx ‐AFx ). The numerical simulations demonstrated that a probability density function that uses 25% of the samples to fully sample the k‐space central area allowed for an optimal balance between limited blurring and artifact incoherence. At all investigated noise levels, the Dice similarity coefficient (DSC) strongly depended on the regularization parameters and acceleration factor. In phantoms, the motion robustness of an NA8‐AF8 undersampling pattern versus NA1‐AF1 was evaluated with simulated and real motion patterns. Differences were assessed with the DSC, which was consistently higher for the NA8‐AF8 compared with the NA1‐AF1 strategy, for both simulated and real cyclic motion patterns (P < 0.001). Both strategies were validated in vivo in mice (n = 2) injected with perfluoropolyether. Here, the images displayed a sharper delineation of the liver with the NA8‐AF8 strategy than with the NA1‐AF1 strategy. In conclusion, we validated the hypotheses that in 19F MRI the combination of undersampling and averaging improves both the sensitivity and the robustness against motion artifacts. 相似文献
4.
Boron–18F containing positron emission tomography radiotracers: advances and opportunities 下载免费PDF全文
Benjamin P. Burke Gonçalo S. Clemente Stephen J. Archibald 《CONTRAST MEDIA & MOLECULAR IMAGING》2015,10(2):96-110
Standard [18F]fluorination methods to form carbon–fluorine bonds can have some limitations such as low yield and the requirement for harsh reaction conditions. Inorganic approaches include the formation of boron–[18F]fluorine bonds and have the potential to give high specific activities at room temperature forming a bond that is stable in vivo. There is considerable potential in future applications, particularly in relation to multimodal imaging and the provision of rapid efficient labelling protocols. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
5.
6.
目的 研究氟涂层镁铝合金的体外生物相容性。方法实验分为空白对照组(N组)、镁铝合金组(M组)、氟涂层镁铝合金组(F组)和阳性对照组(P组)4组。细胞毒性实验:将L929细胞在各组的DMEM浸提液中培养,光学显微镜下观察细胞生长状况。应用WST-1法测量光密度(OD)值。溶血实验:按GB-T16175-2008《医用有机硅材料生物学评价实验方法》第13部分《溶血试验》进行实验。测量各样本的OD值,计算溶血率。豚鼠最大剂量致敏实验,按照GBJ16886.10-2005((医疗器械生物学评价》第10部分《刺激与迟发型超敏反应试验》进行实验。观察激发阶段去除贴附片后24、48、72h豚鼠皮肤致敏情况。结果各观察期F组的形态分级为0级,M组为4级。各组各观察期内OD值差异均有统计学意义(F=312.96,P=0.000)。第3天,实验组OD值均高于P组(1.050±0.065 vs 0.292±0.010)(P〈0.05)。第5天、第7天,F组与N组OD值(1.429±0.096 vs 1.622±0.156,0.928±0.040 vs 50.995±0.070)处于同一水平(P〉0.05),均高于P组(0.270±0.015,0.281±0.006)(P〈0.05)。M组溶血率为68.3%,F组为0.8%。24h、48h和72h后N组、M组、F组皮肤均无红斑。结论氟涂层镁铝合金体外实验显示具有良好的生物相容性。 相似文献
7.
Daniel P. Holt Hayden T. Ravert Robert F. Dannals 《Journal of labelled compounds & radiopharmaceuticals》2016,59(10):411-415
The detailed synthesis and quality control of [18F]T807, radiotracer for tau protein aggregate imaging, are described. The radiotracer synthesis was accomplished in an average of 48 min with an average specific activity at end‐of‐synthesis of over 4.4 TBq/µmole (120 Ci/µmole) and an average radiochemical yield of 32%. Compliance with all standard US Pharmacopeia Chapter <823> acceptance tests was observed. 相似文献
8.
Synthesis and evaluation of a 18F‐labeled 4‐phenylpiperidine‐4‐carbonitrile radioligand for σ1 receptor imaging 下载免费PDF全文
Jiajun Ye Xia Wang Winnie Deuther‐Conrad Jinming Zhang Jianzhou Li Xiaojun Zhang Liang Wang Jörg Steinbach Peter Brust Hongmei Jia 《Journal of labelled compounds & radiopharmaceuticals》2016,59(9):332-339
We report the design and synthesis of several 4‐phenylpiperidine‐4‐carbonitrile derivatives as σ1 receptor ligands. In vitro radioligand competition binding assays showed that all the ligands exhibited low nanomolar affinity for σ1 receptors (Ki(σ1) = 1.22–2.14 nM) and extremely high subtype selectivity (Ki(σ2) = 830–1710 nM; Ki(σ2)/Ki(σ1) = 680–887). [18F]9 was prepared in 42–46% isolated radiochemical yield, with a radiochemical purity of >99% by HPLC analysis after purification, via nucleophilic 18F‐ substitution of the corresponding tosylate precursor. Biodistribution studies in mice demonstrated high initial brain uptakes and high brain‐to‐blood ratios. Administration of SA4503 or haloperidol 5 min prior to injection of [18F]9 significantly reduced the accumulation of radiotracers in organs known to contain σ1 receptors. Two radioactive metabolites were observed in the brain at 30 min after radiotracer injection. [18F]9 may serve as a lead compound to develop suitable radiotracers for σ1 receptor imaging with positron emission tomography. 相似文献
9.
背景:改性玻璃离子水门汀提高了玻璃离子水门汀的机械性能、耐磨性和美观性,被逐渐应用于口腔临床的诸多方面,但对改性玻璃离子水门汀的氟释放行为和溶解特性尚不明确。目的:考察FujiⅡ传统型玻璃离子水门汀、Fuji Plus羟基磷灰石改性型玻璃离子水门汀、FujiⅨ金属增强型玻璃离子水门汀及FujiⅡLC光固化树脂改性型玻璃离子水门汀在人工唾液中的氟释放行为与溶解特性。方法:将4种玻璃离子水门汀试样浸没在人工唾液中,采用氟离子选择性电极测定试样浸泡0-28 d的氟释放量;利用分析天平测定试样浸泡3,7,14,28 d的质量,以算溶解率,采用SPSS软件和Origin软件分别进行氟释放量统计学分析和非线性拟合回归分析。结果与结论:各玻璃离子水门汀均在第1天达到最高的氟释放量,在随后几天迅速下降,之后保持稳定,其中FujiⅡLC光固化树脂改性型玻璃离子水门汀的氟释放单日量与累积量,以及溶解率显著高于其他3种玻璃离子水门汀(P &lt;0.01)。方程Y=a+b*t0.5+c*t可较好模拟氟释放累积量变化过程,氟释放累积量与溶解率近似呈正比例关系。FujiⅡLC光固化树脂改性型玻璃离子水门汀达到最高的氟释放累积量与溶解率比值。 相似文献
10.
Tsuneo Saga Yuji Nakamoto Takayoshi Ishimori Takahiro Inoue Yoichi Shimizu Hiroyuki Kimura Shusuke Akamatsu Takayuki Goto Hiroyuki Watanabe Kosuke Kitaguchi Masao Watanabe Masahiro Ono Hideo Saji Osamu Ogawa Kaori Togashi 《Cancer science》2019,110(2):742-750
This first‐in‐man study was carried out to evaluate the safety, whole‐body distribution, dose estimation, and lesion accumulation of 18F‐FSU‐880, a newly developed probe targeting prostate‐specific membrane antigen. Six prostate cancer patients with known metastatic lesions underwent serial whole‐body PET/computed tomography (CT) with 18F‐FSU‐880. Blood and urine were analyzed before and after PET/CT. Accumulation of 18F‐FSU‐880 in organs and metastatic lesions in serial PET images were evaluated by measuring the standardized uptake values. From the biodistribution data, the organ doses and whole‐body effective dose were calculated using OLINDA/EXM software was developed by Dr. Michael Stabin of Vanderbilt University, Nashville, Tennessee, USA. 18F‐FSU‐880 PET/CT could be carried out without significant adverse effects. High physiological uptake was observed in the salivary/lachrymal glands and kidneys. The effective dose was calculated to be 0.921 × 10?2 mSv/MBq. Known metastatic lesions were clearly visualized with high image contrast that increased with time, except in 1 patient, whose bone metastases were well‐controlled and inactive. The PET/CT with 18F‐FSU‐880 could be carried out safely and could clearly visualize active metastatic lesions. The present results warrant further clinical studies with a larger number of cases to verify the clinical utility of 18F‐FSU‐880 PET/CT in the management of prostate cancer patients. 相似文献