全文获取类型
收费全文 | 17321篇 |
免费 | 1425篇 |
国内免费 | 314篇 |
学科分类
医药卫生 | 19060篇 |
出版年
2024年 | 23篇 |
2023年 | 331篇 |
2022年 | 429篇 |
2021年 | 830篇 |
2020年 | 755篇 |
2019年 | 666篇 |
2018年 | 660篇 |
2017年 | 629篇 |
2016年 | 653篇 |
2015年 | 628篇 |
2014年 | 1134篇 |
2013年 | 1378篇 |
2012年 | 1062篇 |
2011年 | 1093篇 |
2010年 | 814篇 |
2009年 | 789篇 |
2008年 | 781篇 |
2007年 | 757篇 |
2006年 | 675篇 |
2005年 | 581篇 |
2004年 | 500篇 |
2003年 | 441篇 |
2002年 | 311篇 |
2001年 | 300篇 |
2000年 | 292篇 |
1999年 | 248篇 |
1998年 | 239篇 |
1997年 | 222篇 |
1996年 | 196篇 |
1995年 | 255篇 |
1994年 | 152篇 |
1993年 | 128篇 |
1992年 | 135篇 |
1991年 | 135篇 |
1990年 | 116篇 |
1989年 | 87篇 |
1988年 | 104篇 |
1987年 | 78篇 |
1986年 | 77篇 |
1985年 | 83篇 |
1984年 | 67篇 |
1983年 | 41篇 |
1982年 | 36篇 |
1981年 | 27篇 |
1980年 | 30篇 |
1979年 | 22篇 |
1978年 | 22篇 |
1977年 | 16篇 |
1975年 | 10篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Stuart A. Batterman Alfred Franzblau Nanzheng Zhou 《International archives of occupational and environmental health》1996,68(4):268-274
Dermal exposures of methanol were administered in a clinical study designed to compare several biological indicators. Four
subjects were exposed in five exposure sessions of varying length. In each session, a sequence of measurements of methanol
concentrations in blood, breath, and headspace samples of air at exposed and unexposed skin were collected before and after
dermal exposures. Skin headspace samples, collected in gas sampling bags, were designed to reflect equilibrium skin: air partitioning.
At exposed skin, headspace samples were highly elevated for at least 8 h following exposure, indicating the presence of a
methanol reservoir in skin. After exposure, methanol concentrations at exposed skin showed a rapid initial decline, then a
slower first-order decrease. Methanol concentrations were clearly detectable in headspace samples at unexposed skin. Substantial
transfer from exposed skin occurred due to mechanical contact and washing. When transfer was restricted, surface concentrations
at unexposed skin were similar to levels in breath and were strongly correlated to methanol concentrations in blood. While
results are preliminary due to the small sample sizes and several unresolved experimental issues, the simple, rapid, and noninvasive
skin headspace measurements appear useful as a biological exposure indicator that clearly shows the presence and site of a
dermal exposure, and measurements at unexposed skin reflect concentrations in blood.
Received: 14 March 1995/Accepted: 3 November 1995 相似文献
62.
63.
Little is known about whether patients with photosensitive disorders exhibit a different ultraviolet erythema time course from subjects with a normal response to sunlight. We have described the application of an instrument for ambulatory monitoring of the development of ultraviolet erythema by a reflectance method in a group of patients with chronic actinic dermatitis (CAD) and in a group of normal subjects. Investigations of the time course have been reported previously but the techniques used relied upon manual measurement. Consequently sampling frequencies have been considerably lower than the one-minute sample rate used here. We have not demonstrated any difference in the rate at which erythema develops and peaks between patients with CAD and subjects with a normal response to sunlight. 相似文献
64.
Hans-Günter Neumann 《International archives of occupational and environmental health》1988,60(3):151-155
Summary Analysis of hemoglobin adducts in blood samples is suitable for the biological monitoring of genotoxic chemicals. The method is specific because the compound to which the individual was exposed is identified. The sensitivity of the method depends on the analytical procedure applied, but is hardly limiting since large amounts of the protein can be obtained. The method provides not only information about the internal exposure to the environmental chemical, but also about the individual's capacity to generate ultimate genotoxic metabolites from it. Since macromolecular damage in blood cells is correlated to that in potential target tissues, this information is relevant to risk assessment, insofar as macromolecular damage produced by a specific chemical can be correlated with the development of tumors. 相似文献
65.
急性心肌梗死再灌注期间的心电变化特征 总被引:1,自引:1,他引:0
目的 探讨急性心肌梗死 (AMI)再灌注期间的心电变化特征。方法 46例经急诊冠状动脉造影明确为成功再灌注的AMI,其中 2 4例接受溶栓治疗和 2 2例接受直接经皮腔内冠状动脉成形 ,于发病的 6小时内以动态心电图技术持续2 4小时监测心电图变化 ,并与 1 5例无灌注者进行对比。结果 ①再灌注发生后 ,相应导联ST段迅速下降 ,约 2小时达较低水平 ;同时 ,T波正向振幅进行性降低 ,距再灌注 0~ 2 2 (2 7± 4 5)小时呈现T波倒置并逐渐加深。②再灌注后的 1小时内 ,室性心律失常明显增加 ,6~ 8小时后显著减少。结论 AMI早期再灌注发生后呈现特征性心电变化 ,及时识别这些特征将有助于临床评估再灌注状态和危险度分层 相似文献
66.
The authors present the third installment of the guidelines and recommendations from the Safety Committee of the Society for Magnetic Resonance Imaging (now the Society of Magnetic Resonance) concerning various issues related to the safety and management of patients undergoing magnetic resonance (MR) procedures. This document was developed to provide standardized and consistent information for use by health practitioners involved in screening patients or other individuals for MR procedures. 相似文献
67.
Tommi Sukuvaara Erkki M. J. Koski Aki Mäkivirta Aarno Kari 《Journal of clinical monitoring and computing》1994,10(2):117-126
A knowledge-based alarm system for intensive care monitoring was designed, built, tested on-line, and evaluated. The system is a functional prototype of a highly specific patient monitor providing alarms on hypovolemia, hyperdynamic state, left ventricular failure and hypoventilation. These intelligent alarm functions aim to maintain the quality of patient monitoring even if nurses' attention is temporarily reduced or focused elsewhere. The alarm system has an electronic access to data available in a multichannel patient monitor and the patient data management system of the intensive care unit. Median filtering, trend estimation, and rule-based reasoning are applied when processing the measured variables and estimating the patient's state. 相似文献
68.
微型无线收发器在中央监护系统中的应用 总被引:3,自引:0,他引:3
中央监护系统能够实现对病人的生理或生化参数连续、长时间、自动、实时监测,并经分析、处理后实现多类别自动报警、自动记录及对诊断结果进行综合判断等。传统的多参数生理监护系统主要是通过各种专用电缆来实现网络化,在增加产品成本的同时也加大了施工的难度。本文在分析了无线收发芯片XE1201的工作原理基础上,重点介绍了应用其开发无线收发模块的原理和方法,并利用此模块构建了无线中央监护系统,继而对整个系统的性能进行了测试。该系统已在实验室中实现,并对心电(ECG)、无创血压、血氧饱和度(SPO2)等多生理参数进行实时监护,将信息提供给医院内的网络,以供访问使用。 相似文献
69.
1999~2001年全国治疗药物监测室间质评结果 总被引:1,自引:0,他引:1
目的:通过开展室间质量评价活动提高临床实验室的检验结果质量。方法:每年向参加治疗药物监测(TDM)室间质量评价活动的单位发放质控品10个批号,测定项目包括茶碱、地高辛、苯妥英、苯巴比妥、卡马西平和环孢菌素A,实验室用常规方法测定并回报测定结果,经计算机软件对全部结果进行统计分析。结果:2001年参加TDM室间质评的实验室数为48家,测定结果的平均及格率分别为茶碱94.2%、地高辛82.6%、苯妥英83.8%、苯巴比妥88.4%、卡马西平94.2和环孢菌素A92.4%。1999~2001年全国TDM室间质评的年平均及格率分别为78.7%、84.7%和89.3%。不同测定方法的精密度分别为茶碱4.4%~14.2%、地高辛11.5%~21.9%、苯妥英8.5%~29.5%、苯巴比妥8.2%~13.9%、卡马西平10.8%~12.6%和环孢菌素A15.5%~16.6%。结论:多数参加TDM室间质评实验室的测定结果有较好的一致性,及格率逐年上升,但参加TDM室间质评的实验室数占开展TDM的实验室总数的比例较低,在不同的测定方法间还存在较大的差异。 相似文献
70.
Bente E. Moen Bjrg E. Hollund Morten Berntsen Ragnar Flo Knut Rasmus Kyvik Trond Riise 《American journal of industrial medicine》1995,27(4):555-564
Occupational exposure to carcinogenic agents on the decks on six Norwegian crude oil tankers was examined in five harbors. The purpose of the study was to evaluate the need for improving the working environment on deck on these tankers. Technical arrangments and the work itself on the deck were observed during loading or unloading. Occupational monitoring was performed by active sampling of benzene, polyaromatic hydrocarbons, and some aldehydes. The crew answered a questionnaire concerning their work, use of protective equipment, and occurrence of acute symptoms. The levels of air-borne carcinogenic agents were low, probably due to closed loading systems on all tankers. However, the seamen reported discomfort during the work that may be related to other chemical agents in the cargo. The seamen were frequently painting with lead chromate paint without using personal protective equipment. This type of chemical exposure should be evaluated. 相似文献