全文获取类型
收费全文 | 19860篇 |
免费 | 1890篇 |
国内免费 | 944篇 |
专业分类
耳鼻咽喉 | 86篇 |
儿科学 | 216篇 |
妇产科学 | 178篇 |
基础医学 | 1423篇 |
口腔科学 | 406篇 |
临床医学 | 2061篇 |
内科学 | 1271篇 |
皮肤病学 | 255篇 |
神经病学 | 779篇 |
特种医学 | 656篇 |
外科学 | 934篇 |
综合类 | 3665篇 |
现状与发展 | 2篇 |
一般理论 | 7篇 |
预防医学 | 3889篇 |
眼科学 | 378篇 |
药学 | 3067篇 |
36篇 | |
中国医学 | 2896篇 |
肿瘤学 | 489篇 |
出版年
2024年 | 26篇 |
2023年 | 304篇 |
2022年 | 424篇 |
2021年 | 621篇 |
2020年 | 737篇 |
2019年 | 675篇 |
2018年 | 632篇 |
2017年 | 784篇 |
2016年 | 868篇 |
2015年 | 767篇 |
2014年 | 1306篇 |
2013年 | 1620篇 |
2012年 | 1293篇 |
2011年 | 1395篇 |
2010年 | 1004篇 |
2009年 | 986篇 |
2008年 | 992篇 |
2007年 | 1079篇 |
2006年 | 915篇 |
2005年 | 712篇 |
2004年 | 623篇 |
2003年 | 572篇 |
2002年 | 472篇 |
2001年 | 422篇 |
2000年 | 376篇 |
1999年 | 334篇 |
1998年 | 233篇 |
1997年 | 229篇 |
1996年 | 190篇 |
1995年 | 212篇 |
1994年 | 195篇 |
1993年 | 136篇 |
1992年 | 151篇 |
1991年 | 154篇 |
1990年 | 144篇 |
1989年 | 138篇 |
1988年 | 118篇 |
1987年 | 99篇 |
1986年 | 125篇 |
1985年 | 80篇 |
1984年 | 86篇 |
1983年 | 78篇 |
1982年 | 84篇 |
1981年 | 63篇 |
1980年 | 60篇 |
1979年 | 58篇 |
1978年 | 34篇 |
1977年 | 20篇 |
1976年 | 25篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Species identification of unknown biological samples is crucial for forensic applications, especially in cases of explosion, disaster accidents, and body mutilation after murdering, as well as poaching, illegal trade in endangered animals, and meat food fraud. In this study, we identified 60 volatile organic compounds (VOCs) in fresh skeletal muscle tissues of seven different animal species (cattle, sheep, pigs, rabbits, rats, chickens and carp) and a human dead body by headspace-gas-chromatography ion-mobility spectrometry (HS-GC-IMS), and compared their differences by retention time, drift time and molecular weight. The results showed that these VOCs formed different gallery plot fingerprints in the skeletal muscle tissues of the human dead body and seven animal species. Principal component analysis (PCA) showed significantly different fingerprints between these species, and these fingerprints maintained good stability between the species and within the same species. Some VOCs have high species specificity, while VOCs of human fresh muscle tissues from different individual sources have little difference, demonstrating that all tested muscle tissue samples could be distinguished based on different VOCs. HS-GC-IMS has proved to be a rapid, high-throughput, highly sensitive and specific species identification method, which can be used for forensic species identification in criminal cases and disaster accidents, as well as detection in the field of food safety, such as meat fraud and adulteration. 相似文献
2.
蕲蛇是《中国药典》收载的三种蛇类药材(含蕲蛇、乌梢蛇、金钱白花蛇)之一,具有祛风、通络、定惊止痉等功效,其药用价值和经济价值较高,市场需求量较大,为贵细药材。近年来,由于野生资源逐渐匮乏,在经济利益驱使下,蕲蛇商品普遍存在着伪品、混淆品、掺假品,这种质量不一、以次充好、以假代真的情况容易导致用药安全问题。本文通过总结蕲蛇的性状鉴别、显微鉴别、理化鉴别和分子鉴别,以期为蕲蛇等蛇类药材的真伪鉴别和质量的优劣检测提供思路,为进一步鉴别研究、制剂开发提供参考依据,确保用药质量。 相似文献
3.
4.
目的 建立一种能够快速鉴定人参和西洋参的双重实时荧光PCR方法。方法 通过对人参属及其近似种基因序列的分析比对,设计特异性的引物探针,建立双重实时荧光PCR检测方法。PCR反应体系为Premix Ex Taq (Probe qPCR) 10 μL,人参上下游引物各0.5 μL,西洋参上下游引物各0.3 μL,人参与西洋参特异性探针各0.4 μL,DNA模板2 μL,灭菌去离子水补至20 μL。反应条件为95℃预变性30 s;然后以95℃变性5 s,60℃退火延伸30 s进行40个循环。应用该方法测试了27份DNA样品,包括7份人参、6份西洋参、4份人参与西洋参混合样、10份其他人参属样品及其他常见中药材样品的DNA,以确定该方法的特异性。将人参与西洋参样品DNA混合后10倍稀释成不同浓度后进行检测,用以确定该方法的灵敏度。结果 人参及西洋参样品均在特定的荧光通道下出现典型的阳性扩增曲线,人参与西洋参混合样品均同时出现两条阳性扩增曲线,其它对照样品及空白对照均没有出现阳性扩增曲线。灵敏度检测结果显示该方法检测人参及西洋参的最低检测限均为2 pg DNA/反应。结论 本实验建立的双重实时荧光PCR方法能够同时快速、准确、灵敏地鉴别出人参和西洋参。 相似文献
5.
Arterial spin labeling (ASL) imaging is a powerful magnetic resonance imaging technique that allows to quantitatively measure blood perfusion non-invasively, which has great potential for assessing tissue viability in various clinical settings. However, the clinical applications of ASL are currently limited by its low signal-to-noise ratio (SNR), limited spatial resolution, and long imaging time. In this work, we propose an unsupervised deep learning-based image denoising and reconstruction framework to improve the SNR and accelerate the imaging speed of high resolution ASL imaging. The unique feature of the proposed framework is that it does not require any prior training pairs but only the subject's own anatomical prior, such as T1-weighted images, as network input. The neural network was trained from scratch in the denoising or reconstruction process, with noisy images or sparely sampled k-space data as training labels. Performance of the proposed method was evaluated using in vivo experiment data obtained from 3 healthy subjects on a 3T MR scanner, using ASL images acquired with 44-min acquisition time as the ground truth. Both qualitative and quantitative analyses demonstrate the superior performance of the proposed txtc framework over the reference methods. In summary, our proposed unsupervised deep learning-based denoising and reconstruction framework can improve the image quality and accelerate the imaging speed of ASL imaging. 相似文献
6.
Previous event-related potential (ERP) studies show that a salient lateral sound activates the visual cortex more strongly contralateral to the sound, observed as an auditory-evoked contralateral occipital positivity (ACOP). Studies showed that this activation enhances the early cortical processing of co-localized visual stimuli presented after, reflected by better detection rates, better discrimination, and sharper perceived contrast. We replicated the ACOP, using earphones, and tested whether auditory cuing can influence temporal order judgments (TOJ) for two visual stimuli (horizontal arrangement) as well as if the ACOP would predict the amplitude of this influence. A lateral salient sound was followed, after 150 or 630 ms, by the visual presentation of a pair of disks, one in left and one in right hemifield, with variable SOA. The TOJ task was to indicate which disk appeared first or which disk appeared second (controlling for response bias). We observed an ACOP at posterior electrode sites and confirmed our hypothesis that the lateral sound influenced TOJ by accelerating the perception of the disk presented on the cued side, even though the sound was irrelevant to the task. Furthermore, the ACOP amplitude was correlated to this visual perceptual change, indicating that a larger change in brain activity was associated with a faster processing of co-localized visual stimuli. 相似文献
7.
摘要:目的以分子测序为参考 ,评估形态学、基质辅助激光解吸电离飞行时间质谱对毛霉目真菌的鉴定能力,分析毛霉目真菌对两性霉素B、泊沙康唑的体外药敏特点。方法收集 2018年1月-2022年2月广东省人民医院25例毛霉病住院患者标
本,进行镜检并对培养的茵落行形态学鉴定、质谱鉴定、分子测序和体外药敏试验。结果KOH 湿片法阳性率(76%)高于革兰染色法(32%),差异有统计学意义(P<0.05);形态学鉴定可将68%的菌株鉴定到属水平,3株鉴定错误,2株无法鉴定;将所
有菌株进行质谱鉴定,单用IVD和RUO数据库鉴定率分别为56%和44%,两库联合可将鉴定率提高为64%。毛霉目真菌对两性霉素B的抑制50%菌株生长的最小抑菌浓度(MIC3o)为1μg/mL,根霉属相比其他属对两性霉素B表现出较高的MIC
值,其中2株MIC>32 μg/mL,另2株MIC为8 μg/mL;根霉属对泊沙康唑的MICso为0.5 μg/mL,横梗霉属MICgo为4 μg/ mL,小克银汉霉属MICg0为2 μg/mL,有部分菌株表现出较低MIC值,同样亦有部分菌株对泊沙康唑表现出较高的MIC 值。结论
将传统镜检、培养与质谱技术和分子技术相结合,尽量将毛霉目真菌准确鉴定到种,并积极开展毛霉体外药敏试验,可为临床治疗提供参考依据。 相似文献
8.
9.
《Research in social & administrative pharmacy》2022,18(2):2345-2349
This commentary looks at the process of conducting a systematic review of surveys and validated questionnaires. Surveys and other questionnaire style tools are often used in the field of social and administrative pharmacy, to capture beliefs, attitudes and experiences of patients and healthcare professionals (including pharmacists). Currently, there is little guidance available on how to conduct a systematic review of these types of studies. Considerations related to the process of a systematic review are highlighted, including identification of articles, data extraction, assessing quality of articles and synthesis and analysis of data. 相似文献
10.
Loren Saulsberry PhD Ankur Bhargava MD MPH Sharon Zeng BA Jason B. Gibbons PhD Cody Brannan MS Diane S. Lauderdale PhD Robert D. Gibbons PhD 《Health services research》2023,58(4):873-881