全文获取类型
收费全文 | 919篇 |
免费 | 70篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 18篇 |
妇产科学 | 58篇 |
基础医学 | 138篇 |
口腔科学 | 11篇 |
临床医学 | 45篇 |
内科学 | 131篇 |
皮肤病学 | 14篇 |
神经病学 | 104篇 |
特种医学 | 33篇 |
外科学 | 117篇 |
综合类 | 2篇 |
一般理论 | 2篇 |
预防医学 | 40篇 |
眼科学 | 16篇 |
药学 | 68篇 |
中国医学 | 5篇 |
肿瘤学 | 188篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 26篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 18篇 |
2017年 | 19篇 |
2016年 | 19篇 |
2015年 | 21篇 |
2014年 | 36篇 |
2013年 | 43篇 |
2012年 | 64篇 |
2011年 | 66篇 |
2010年 | 41篇 |
2009年 | 31篇 |
2008年 | 53篇 |
2007年 | 48篇 |
2006年 | 50篇 |
2005年 | 50篇 |
2004年 | 34篇 |
2003年 | 35篇 |
2002年 | 19篇 |
2001年 | 25篇 |
2000年 | 18篇 |
1999年 | 21篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 13篇 |
1995年 | 5篇 |
1993年 | 7篇 |
1992年 | 20篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1978年 | 3篇 |
1919年 | 3篇 |
1909年 | 2篇 |
1908年 | 2篇 |
1903年 | 2篇 |
1901年 | 2篇 |
1900年 | 6篇 |
1882年 | 2篇 |
排序方式: 共有991条查询结果,搜索用时 15 毫秒
71.
72.
Clare E Collins Philip J Morgan Pennie Jones Kate Fletcher Julia Martin Elroy J Aguiar Ashlee Lucas Melinda Neve Patrick McElduff Robin Callister 《BMC public health》2010,10(1):669
Background
Obesity rates in adults continue to rise and effective treatment programs with a broad reach are urgently required. This paper describes the study protocol for a web-based randomized controlled trial (RCT) of a commercially available program for overweight and obese adult males and females. The aim of this RCT was to determine and compare the efficacy of two web-based interventions for weight loss and maintenance of lost weight. 相似文献73.
Katja Reuter Melissa L Wilson Meghan Moran NamQuyen Le Praveen Angyan Anuja Majmundar Elsi M Kaiser Jennifer B Unger 《JMIR Public Health and Surveillance》2021,7(2)
BackgroundPublic health organizations have begun to use social media to increase awareness of health harm and positively improve health behavior. Little is known about effective strategies to disseminate health education messages digitally and ultimately achieve optimal audience engagement.ObjectiveThis study aims to assess the difference in audience engagement with identical antismoking health messages on three social media sites (Twitter, Facebook, and Instagram) and with a referring link to a tobacco prevention website cited in these messages. We hypothesized that health messages might not receive the same user engagement on these media, although these messages were identical and distributed at the same time.MethodsWe measured the effect of health promotion messages on the risk of smoking among users of three social media sites (Twitter, Facebook, and Instagram) and disseminated 1275 health messages between April 19 and July 12, 2017 (85 days). The identical messages were distributed at the same time and as organic (unpaid) and advertised (paid) messages, each including a link to an educational website with more information about the topic. Outcome measures included message engagement (ie, the click-through rate [CTR] of the social media messages) and educational website engagement (ie, the CTR on the educational website [wCTR]). To analyze the data and model relationships, we used mixed effects negative binomial regression, z-statistic, and the Hosmer-Lemeshow goodness-of-fit test.ResultsComparisons between social media sites showed that CTRs for identical antitobacco health messages differed significantly across social media (P<.001 for all). Instagram showed the statistically significant highest overall mean message engagement (CTR=0.0037; 95% CI 0.0032-0.0042), followed by Facebook (CTR=0.0026; 95% CI 0.0022-0.0030) and Twitter (CTR=0.0015; 95% CI 0.0013-0.0017). Facebook showed the highest as well as the lowest CTR for any individual message. However, the message CTR is not indicative of user engagement with the educational website content. Pairwise comparisons of the social media sites differed with respect to the wCTR (P<.001 for all). Messages on Twitter showed the lowest CTR, but they resulted in the highest level of website engagement (wCTR=0.6308; 95% CI 0.5640-0.6975), followed by Facebook (wCTR=0.2213; 95% CI 0.1932-0.2495) and Instagram (wCTR=0.0334; 95% CI 0.0230-0.0438). We found a statistically significant higher CTR for organic (unpaid) messages (CTR=0.0074; 95% CI 0.0047-0.0100) compared with paid advertisements (CTR=0.0022; 95% CI 0.0017-0.0027; P<.001 and P<.001, respectively).ConclusionsOur study provides evidence-based insights to guide the design of health promotion efforts on social media. Future studies should examine the platform-specific impact of psycholinguistic message variations on user engagement, include newer sites such as Snapchat and TikTok, and study the correlation between web-based behavior and real-world health behavior change. The need is urgent in light of increased health-related marketing and misinformation on social media. 相似文献
74.
Geert M Villeirs Koenraad L Verstraete Wilfried J De Neve Gert O De Meerleer 《Radiotherapy and oncology》2005,76(1):99-106
Magnetic resonance imaging (MRI) offers superb soft tissue contrast on T2-weighted images and allows direct multiplanar image acquisition. It can show the internal prostatic anatomy, prostatic margins, and the extent of prostatic tumors in much more detail than computed tomography (CT) images. The present article reviews some key prostatic and periprostatic radiologic landmarks that can be helpful for the radiotherapist using T2-weighted MRI as an adjunct to CT in treatment planning for prostate cancer. 相似文献
75.
76.
Valérie Fonteyne Wilfried De Neve Geert Villeirs Carlos De Wagter Gert De Meerleer 《Radiotherapy and oncology》2007,84(2):156-163
PURPOSE: To report on: 1. Late radiotherapy-induced lower intestinal toxicity (RILIT) after intensity-modulated radiotherapy (IMRT) for prostate cancer. 2. The correlation between late RILIT and volume parameters of the rectum, sigmoid colon and small bowel. MATERIALS AND METHODS: We included 241 patients with a follow-up of >or=18 months for this analysis. Late RILIT consisted of 8 different symptoms, comprising the 5 symptoms from the RTOG toxicity score supplemented with urgency, fecal incontinence and anal pain. Late RILIT and late RTOG toxicity were scored prospectively and correlated with: 1. Different rectum, sigmoid colon and small bowel volume parameters. 2. Patient-related morbidity. We calculated the median, quartile and percentiles for the different volume parameters and correlated them with grade 1-3 late RILIT. RESULTS: Median follow-up was 42 months. Three patients developed grade 3 red blood loss. We registered grade 2 RILIT and RTOG toxicity in 13% and 10%, respectively, the most frequent grade 1 symptom being fecal urgency. The intermediate rectal volume parameters were significantly correlated with late RILIT. We were able to calculate cut-off dose-volume histograms (DVHs) that predict for grade 0-2 RILIT. CONCLUSIONS: After IMRT for prostate cancer, the overall incidence of grade >or=2 RILIT is low. Cut-off DVHs can be used for patient counseling. 相似文献
77.
Comparison of effects of chronic inflammation and long-term prednisolone administration on zinc metabolism in rats 总被引:1,自引:0,他引:1
J Fontaine J Neve A Peretz F Pelen J P Famaey 《International journal of tissue reactions》1989,11(5):253-259
It is well known that plasma zinc is depressed in animals following administration of endotoxin, endogenous pyrogen, interleukin-1, and glucocorticoids. The modification is related to an induction of liver metallothionein causing an accumulation of the element in this organ. The changes in zinc metabolism induced by adjuvant arthritis in rats evidenced a redistribution of body zinc with a rapid and sustained decrease in plasma zinc that occurred simultaneously with an increase in liver zinc levels, and slower modification in erythrocyte and femur zinc concentrations. These effects were compared to those induced by a long-term corticosteroid administration in healthy rats. Male Wistar rats received either a commercially available complete maintenance diet or the same diet enriched with prednisolone at a level providing 1 mg prednisolone/kg body weight. Groups of animals were sacrificed after 3 or 5 weeks' treatment. Ingested food quantity, total body weight, total serum proteins and serum albumin were similar in treated and control rats. No significant modifications in parameters of zinc status could be observed after 3 weeks of treatment. However after 5 weeks, plasma zinc was significantly lower in treated rats as compared to controls, but modifications in liver, erythrocyte and femur zinc did not reach statistical significance. Changes induced by long-term corticosteroid administration are therefore less intense than those due to the inflammatory process of adjuvant arthritis. 相似文献
78.
79.
Van Sassenbroeck DK De Neve N De Paepe P Belpaire FM Verstraete AG Calle PA Buylaert WA 《Clinical toxicology (Philadelphia, Pa.)》2007,45(5):533-538
Case reports mention a sudden awakening from GHB-associated coma but do not specify its time course. The aim of the present case series was to investigate the time course of the awakening from GHB intoxication and the relationship to plasma concentrations of GHB and the presence of other drugs. Unconscious (GCS or=12 was 30 minutes (range 10 to 50 minutes). A subgroup of five patients had a GCS of 3 upon arrival and remained at 3 for a median time of 60 minutes (range 30 to 110 minutes), while the median time for the transition between the last point with GCS 3 and the first with GCS 15 was 30 minutes (range 20 to 60 minutes). This case series illustrates that patients with GHB intoxications remain in a deep coma for a relatively long period of time, after which they awaken over about 30 minutes. This awakening is accompanied by a small change in GHB concentrations. A confounding factor in these observations is co-ingested illicit drugs. 相似文献
80.
Laurent Coque Shibani Mukherjee Jun-Li Cao Sade Spencer Marian Marvin Edgardo Falcon Michelle M Sidor Shari G Birnbaum Ami Graham Rachael L Neve Elizabeth Gordon Angela R Ozburn Matthew S Goldberg Ming-Hu Han Donald C Cooper Colleen A McClung 《Neuropsychopharmacology》2011,36(7):1478-1488
Lithium has been used extensively for mood stabilization, and it is particularly efficacious in the treatment of bipolar mania. Like other drugs used in the treatment of psychiatric diseases, it has little effect on the mood of healthy individuals. Our previous studies found that mice with a mutation in the Clock gene (ClockΔ19) have a complete behavioral profile that is very similar to human mania, which can be reversed with chronic lithium treatment. However, the cellular and physiological effects that underlie its targeted therapeutic efficacy remain unknown. Here we find that ClockΔ19 mice have an increase in dopaminergic activity in the ventral tegmental area (VTA), and that lithium treatment selectively reduces the firing rate in the mutant mice with no effect on activity in wild-type mice. Furthermore, lithium treatment reduces nucleus accumbens (NAc) dopamine levels selectively in the mutant mice. The increased dopaminergic activity in the Clock mutants is associated with cell volume changes in dopamine neurons, which are also rescued by lithium treatment. To determine the role of dopaminergic activity and morphological changes in dopamine neurons in manic-like behavior, we manipulated the excitability of these neurons by overexpressing an inwardly rectifying potassium channel subunit (Kir2.1) selectively in the VTA of ClockΔ19 mice and wild-type mice using viral-mediated gene transfer. Introduction of this channel mimics the effects of lithium treatment on the firing rate of dopamine neurons in ClockΔ19 mice and leads to a similar change in dopamine cell volume. Furthermore, reduction of dopaminergic firing rates in ClockΔ19 animals results in a normalization of locomotor- and anxiety-related behavior that is very similar to lithium treatment; however, it is not sufficient to reverse depression-related behavior. These results suggest that abnormalities in dopamine cell firing and associated morphology underlie alterations in anxiety-related behavior in bipolar mania, and that the therapeutic effects of lithium come from a reversal of these abnormal phenotypes. 相似文献