全文获取类型
收费全文 | 6660篇 |
免费 | 495篇 |
国内免费 | 82篇 |
专业分类
耳鼻咽喉 | 44篇 |
儿科学 | 88篇 |
妇产科学 | 116篇 |
基础医学 | 460篇 |
口腔科学 | 172篇 |
临床医学 | 447篇 |
内科学 | 1489篇 |
皮肤病学 | 22篇 |
神经病学 | 254篇 |
特种医学 | 45篇 |
外科学 | 248篇 |
综合类 | 347篇 |
预防医学 | 1759篇 |
眼科学 | 25篇 |
药学 | 1311篇 |
中国医学 | 17篇 |
肿瘤学 | 393篇 |
出版年
2024年 | 3篇 |
2023年 | 73篇 |
2022年 | 112篇 |
2021年 | 180篇 |
2020年 | 181篇 |
2019年 | 220篇 |
2018年 | 225篇 |
2017年 | 210篇 |
2016年 | 206篇 |
2015年 | 226篇 |
2014年 | 456篇 |
2013年 | 654篇 |
2012年 | 377篇 |
2011年 | 487篇 |
2010年 | 353篇 |
2009年 | 359篇 |
2008年 | 493篇 |
2007年 | 413篇 |
2006年 | 372篇 |
2005年 | 233篇 |
2004年 | 194篇 |
2003年 | 169篇 |
2002年 | 119篇 |
2001年 | 114篇 |
2000年 | 99篇 |
1999年 | 71篇 |
1998年 | 55篇 |
1997年 | 67篇 |
1996年 | 57篇 |
1995年 | 57篇 |
1994年 | 57篇 |
1993年 | 40篇 |
1992年 | 45篇 |
1991年 | 44篇 |
1990年 | 36篇 |
1989年 | 22篇 |
1988年 | 21篇 |
1987年 | 20篇 |
1986年 | 11篇 |
1985年 | 22篇 |
1984年 | 19篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1973年 | 5篇 |
1971年 | 4篇 |
排序方式: 共有7237条查询结果,搜索用时 15 毫秒
1.
Smoking and raven IQ 总被引:1,自引:0,他引:1
Nicotine has recently been shown to enhance measures of information processing speed including the decision time (DT) component of simple and choice reaction time and the string length measure of evoked potential waveform complexity. Both (DT and string length) have been previously demonstrated to correlate with performance on standard intelligence tests (IQ). We therefore hypothesised that nicotine is acting to improve intellectual performance on the elementary information processing correlates of IQ. In the current experiment we tested this hypothesis using the Raven Advanced Progressive Matrices (APM) test. APM scores were significantly higher in the smoking session compared to the non-smoking session, suggesting that nicotine acts to enhance physiological processes underlying performance on intellectual tasks. 相似文献
2.
Effects of smoking and drinking on excretion of hippuric acid among toluene-exposed workers 总被引:1,自引:1,他引:0
Osamu Inoue Kazunori Seiji Takao Watanabe Haruo Nakatsuka Chui Jin Shi-Jie Liu Masayuki Ikeda 《International archives of occupational and environmental health》1993,64(6):425-430
Summary In order to investigate possible effects of smoking and drinking on the metabolism of toluence in occupational settings, 206 toluene-exposed men (mean age: 31.4 years) in shoemaking, painting, or surface-coating workshops together with 246 nonexposed control men (36.8 years) were studied for the time-weighted average intensities of exposure to toluene, hippuric acid concentration in shift-end urine samples, and the two social habits of smoking and drinking. The mean daily consumptions of cigarettes and ethanol were about 20 pieces and 10 g among smokers and drinkers, respectively. The geometric mean toluene concentration among the exposed subjects was about 20 ppm, with a maximum of 521 ppm. Regression analysis after classification of the subjects by smoking and drinking clearly demonstrated that the two social habits, when combined, markedly reduce the hippuric acid level in the urine of workers exposed to was a significant association between smoking and drinking habits, which hindered separate evaluation of the effects of the two habits on toluene metabolism. Comparison of the present results with the findings reported in the literature, however, suggested that the observed effects may be attributable to smoking rather than to drinking habits. 相似文献
3.
本文报道对59例健康吸烟者血液流变学9项指标的观察,并与非吸烟组进行比较。吸烟组的血小板粘附率、红细胞压积和全血粘度均较非吸烟组升高,差异非常显著(P<0.001)血浆比粘度在大量吸烟组升高,差异有显著性(P<0.05)说明吸烟使部份血粘滞因素升高,给血液的流变性带来不利影响。不同吸烟量的两组之间各项指标变化无显著差异。本文对发生机制及临床意义略加讨论。 相似文献
4.
Smoking habits in insulin-treated diabetics in Nottinghamshire (UK) and clinic-attending diabetics in Nottingham have been analysed. Compared with the general population, the prevalence of current cigarette smoking is significantly less (p less than 0.001) in both diabetic men and women older than 50 years. Fewer diabetic men over 60 years have ever smoked than in the general population (p less than 0.001) but this finding does not apply to diabetic women. While intervention probably plays some part in this lower prevalence, the most likely explanation is the multiplicative effect of both smoking and diabetes to produce high mortality risks. Actuarial analysis of insulin-treated clinic attenders diagnosed after 1970 showed that at most 14% (95% confidence interval [Cl] 9-18%) of the 183 who smoked at diagnosis had given up 5 years later while a minimum of 8% (95% Cl, 6-11%) of the 313 who were non-smokers had started smoking. Information about the patterns of smoking in patients with chronic disease is incomplete and it appears that too little is being done in clinical services which provide long-term management for these patients to either discourage smoking or determine why some patients give up smoking but others do not. 相似文献
5.
Jason T. Siegel M.A. Eusebio M. Alvaro PhD. M.P.H. Michael Burgoon PhD. 《The Journal of adolescent health》2003,33(6):458-461
This research is supported in part by Arizona Disease Control and Research Commission (ADCRC), Grant #9904 (M. Burgoon, PI). This study assesses how adolescent nonsmokers, at-risk smokers, and smokers differ in perceptions of smoking harms, benefits, and safety. While small differences exist when comparing attitudes and knowledge concerning short- and long-term benefits of smoking, large differences arise when attitudes and knowledge concerning the short-term benefits and the safety of casual smoking are compared. 相似文献
6.
Kathleen M Grant Stephanie Sinclair Kelley Lynette M Smith Sangeeta Agrawal James R Meyer Debra J Romberger 《Alcohol》2007,41(5):381-391
This is a double-blind placebo-controlled study of sustained-release bupropion as a smoking cessation aid in alcoholics undergoing treatment for their alcoholism. Participants (N=58) were enrolled within 1 week of entry into alcohol treatment from community and Veterans Affairs Substance Use Disorder programs. All participants received nicotine patch and were invited to attend a smoking cessation lecture and group. Cigarette smoking and alcohol outcomes were measured at 6 months. Bupropion when added to nicotine patch did not improve smoking outcomes. One third of participants on bupropion reported discontinuing the drug during weeks 1-4. Participants reported cigarette outcomes with nicotine patch that are similar to those seen in the general population. All study participants significantly reduced cigarette use. Comorbid affective disorder or antipersonality disorder did not affect outcomes. Alcohol outcomes were improved in those who discontinued cigarettes. 相似文献
7.
小学生吸烟行为健康教育干预实验 总被引:4,自引:2,他引:2
本文报告了自1991年以来在四川省什邡县所进行的小学生吸烟行为健康教育干预实验。结果显示,实验达到了预期目的。根据基线调查资料对对象儿童吸烟行为影响因素所作的分析以及在此基础上所采取的干预策略是正确的,干预方法是有效的。从而证明了在一个成人吸烟占主流的社会环境中通过健康教育劝阻儿童吸烟尽管是很困难的,但却是完全有成功把握的。 相似文献
8.
Smoking in Pregnancy and Parenthood: What is the Role of Depression, Anxiety and Nicotine Addiction?
Leona Bull Ronan Burke Siobhan Walsh Emma Whitehead 《Early child development and care》2003,173(2):349-356
This paper presents some of the findings from the Smoking in Pregnancy study of attitudes towards smoking among pregnant women, mothers of young children and their partners in East Surrey. As part of the study, respondents completed a General Health Questionnaire to identify mental health difficulties and, if they were smoking at the time of the study, they also completed the Fagerstrom nicotine addiction test. Eleven female respondents had high scores on the General Health Questionnaire, suggesting symptoms of depression, anxiety and/or social dysfunction for these women. There was no evidence that smokers were suffering from greater mental health difficulties than ex-smokers or non-smokers. However, the General Health Questionnaire scores of smokers were positively associated with their level of nicotine dependence. Furthermore, when General Health Questionnaire scores of all respondents were compared with self-reported health status there was a marked discrepancy suggesting under-reporting of symptoms by women. 相似文献
9.
10.
Nicotine discrimination and self-administration in humans as a function of smoking status 总被引:2,自引:2,他引:0
Nicotine’s discriminative stimulus effects may be critical to understanding reinforcement of tobacco smoking. It is not known
whether regular nicotine exposure produces tolerance or sensitivity to these effects. In this study, male and female smokers
(n = 11) and never-smokers (n = 10) were trained to discriminate 20 μg/kg nicotine by nasal spray from placebo (0) on day 1. On day 2, both groups were
tested on generalization of this discrimination across intermittent presentations of 0, 3, 6, 12, and 20 μg/kg nicotine in
random order. Quantitative and quantal behavioral discrimination tasks, used in previous research, were employed. On day 3,
subjects were instructed to self-administer sprays from the 20 μg/kg nicotine versus 0 bottles in a concurrent-choice procedure.
All but one subject (female smoker) learned reliably to discriminate 20 μg/kg nicotine from placebo (≥ 80% correct) on day 1. Nicotine-appropriate responding on day 2 was attenuated in smokers versus never-smokers at 20 μg/kg
on the quantitative task and at 12 μg/kg on the quantal task, suggesting tolerance. There was no difference in responding
at other doses. Smokers also showed attenuated responses on the subjective measure of “head rush”, which was associated with
discrimination responding in both groups. Nicotine self-administration was significantly greater in smokers versus never-smokers,
who self-administered nicotine below chance levels, and was inversely related to discrimination behavior in never-smokers
but unrelated in smokers. Women smokers showed less change in nicotine-appropriate responding across generalization doses,
reported less confidence in discriminating training doses during acquisition on day 1, and tended to self-administer less
nicotine on day 3. These results indicate that smokers may become tolerant to the discriminative stimulus effects of nicotine,
perhaps promoting increased use.
Received: 1 October 1996/Final version: 28 January 1997 相似文献