全文获取类型
收费全文 | 3082篇 |
免费 | 225篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 65篇 |
妇产科学 | 46篇 |
基础医学 | 553篇 |
口腔科学 | 103篇 |
临床医学 | 281篇 |
内科学 | 849篇 |
皮肤病学 | 27篇 |
神经病学 | 280篇 |
特种医学 | 78篇 |
外科学 | 331篇 |
综合类 | 34篇 |
一般理论 | 3篇 |
预防医学 | 225篇 |
眼科学 | 53篇 |
药学 | 194篇 |
中国医学 | 8篇 |
肿瘤学 | 160篇 |
出版年
2023年 | 18篇 |
2022年 | 53篇 |
2021年 | 95篇 |
2020年 | 43篇 |
2019年 | 81篇 |
2018年 | 80篇 |
2017年 | 62篇 |
2016年 | 79篇 |
2015年 | 90篇 |
2014年 | 102篇 |
2013年 | 174篇 |
2012年 | 229篇 |
2011年 | 246篇 |
2010年 | 114篇 |
2009年 | 122篇 |
2008年 | 165篇 |
2007年 | 160篇 |
2006年 | 137篇 |
2005年 | 152篇 |
2004年 | 127篇 |
2003年 | 108篇 |
2002年 | 89篇 |
2001年 | 66篇 |
2000年 | 56篇 |
1999年 | 53篇 |
1998年 | 30篇 |
1997年 | 29篇 |
1996年 | 15篇 |
1995年 | 17篇 |
1994年 | 21篇 |
1993年 | 13篇 |
1992年 | 49篇 |
1991年 | 42篇 |
1990年 | 34篇 |
1989年 | 33篇 |
1988年 | 38篇 |
1987年 | 21篇 |
1986年 | 19篇 |
1985年 | 23篇 |
1984年 | 21篇 |
1979年 | 14篇 |
1978年 | 19篇 |
1977年 | 11篇 |
1976年 | 16篇 |
1975年 | 14篇 |
1974年 | 14篇 |
1973年 | 11篇 |
1971年 | 13篇 |
1969年 | 12篇 |
1967年 | 10篇 |
排序方式: 共有3312条查询结果,搜索用时 0 毫秒
81.
Juliane H. Fröhner Stephan Ripke Sarah Jurk Shu-Chen Li Tobias Banaschewski Arun L.W. Bokde Erin Burke Quinlan Sylvane Desrivières Herta Flor Antoine Grigis Hugh Garavan Andreas Heinz Rüdiger Brühl Jean-Luc Martinot Marie-Laure Paillère Martinot Eric Artiges Frauke Nees Dimitri Papadopoulos Orfanos Luise Poustka Sarah Hohmann Henrik Walter Robert Whelan Gunter Schumann Michael N. Smolka the IMAGEN Consortium 《Alcoholism, clinical and experimental research》2022,46(4):667-681
Background
While drinking alcohol, one must choose between the immediate rewarding effects and the delayed reward of a healthier lifestyle. Individuals differ in their devaluation of a delayed reward based on the time required to receive it, i.e., delay discounting (DD). Previous studies have shown that adolescents discount more steeply than adults and that steeper DD is associated with heavier alcohol use in both groups.Methods
In a large-scale longitudinal study, we investigated whether higher rates of DD are an antecedent or a consequence of alcohol use during adolescent development. As part of the IMAGEN project, 2220 adolescents completed the Monetary Choice Questionnaire as a DD measure, the Alcohol Use Disorders Identification Test, and the Timeline Follow Back interview at ages 14, 16, 18, and 22. Bivariate latent growth curve models were applied to investigate the relationship between DD and drinking. To explore the consequences of drinking, we computed the cumulative alcohol consumption and correlated it with the development of discounting. A subsample of 221 participants completed an intertemporal choice task (iTeCh) during functional magnetic resonance imaging at ages 14, 16, and 18. Repeated-measures ANOVA was used to differentiate between high-risk and low-risk drinkers on the development of neural processing during intertemporal choices.Results
Overall, high rates of DD at age 14 predicted a greater increase in drinking over 8 years. In contrast, on average, moderate alcohol use did not affect DD from ages 14 to 22. Of note, we found indicators for less brain activity in top-down control areas during intertemporal choices in the participants who drank more.Conclusions
Steep DD was shown to be a predictor rather than a consequence of alcohol use in low-level drinking adolescents. Important considerations for future longitudinal studies are the sampling strategies to be used and the reliability of the assessments.82.
83.
Proliferation of totipotent hematopoietic stem cells in vitro with retention of long-term competitive in vivo reconstituting ability. 下载免费PDF全文
C C Fraser S J Szilvassy C J Eaves R K Humphries 《Proceedings of the National Academy of Sciences of the United States of America》1992,89(5):1968-1972
Marrow cells from male mice pretreated with 5-fluorouracil were infected with helper-free neomycin-resistant (neor) recombinant retrovirus and then used to initiate long-term cultures (LTC) on irradiated adherent marrow feeder layers. Four weeks later LTC cells were harvested and injected into lethally irradiated female recipients either alone or together with 2 x 10(5) female marrow cells with selectively compromised long-term repopulating potential to assay for totipotent and competitive repopulating units (CRU), respectively. A total of 46 unique clones were detected in recipients 5 wk to 7 mo after transplant. Half of these clones (22 of 46) included both lymphoid and myeloid progeny. Eight of the 22 lympho-myeloid clones were represented in multiple recipients, in some cases after injection of limiting numbers of CRU, thus indicating repopulation from sibling totipotent stem cells generated during the initial 4-wk period in LTC. Serial analysis of cells released into the nonadherent fraction of LTC for up to 7 wk provided additional evidence of the continuing proliferation in LTC of totipotent stem cells with long-term repopulating potential. The frequency of CRU determined from limiting-dilution analyses of LTC-derived cells was the same for recipients analyzed at 5 wk or 7 mo after transplantation and was also the same whether marrow or thymus repopulation was assessed. These assays showed that concurrent with the expansion of some totipotent cells revealed by retroviral marking, there was a slow but net 6.5-fold decrease in total CRU numbers after 4 wk in LTC. These results show the capacity of some totipotent hematopoietic stem cells to be maintained and amplified over extensive time periods in vitro without diminution of their long-term in vivo repopulating potential. These results also set the stage for analogous studies of human stem cell selection and expansion in vitro, which may be important for future gene therapy protocols. 相似文献
84.
Kyra J. Becker Dorender Dankwa Richard Lee Juliane Schulze Dannielle Zierath Patricia Tanzi Kevin Cain Alexander Dressel Dean Shibata Jonathan Weinstein 《Neurocritical care》2014,21(1):140-146
Background
Infection is a common phenomenon following stroke, and adversely affects outcome. Previous studies suggest that interleukin-1 receptor antagonist (IL-1ra) and single nucleotide polymorphisms (SNPs) in the IL1RN gene might influence the risk of post-stroke infection and outcome. In this study, we addressed the effects of the rs4251961 SNP in IL1RN on infection risk and outcome.Methods
Subjects with acute ischemic stroke were enrolled within 72 h of symptom onset and followed up to 1 year. Plasma IL-1ra was measured at multiple time points and outcome assessed at 1, 3, 6, and 12 months. Active surveillance for infection occurred while subjects were hospitalized. Subjects were genotyped for the IL1RN rs4251961 polymorphism.Results
In the population of 113 subjects for this study, those with the minor C allele of rs4251961 polymorphism in IL1RN were more likely to be Caucasian, hypertensive, and to be afflicted with coronary heart disease. Higher plasma IL-1ra was associated with an increased risk of infection (other than pneumonia), and the minor C allele of rs4251961 was independently associated with a decreased risk of infection (other than pneumonia). Initial plasma IL-1ra was not predictive of long-term outcome, but patients with the minor C allele of rs4251961 were more likely to experience good (modified Rankin Score <2) long-term outcome.Conclusions
These data indicate that IL-1ra and IL1RN may influence the risk of infection after stroke, but this influence seems limited to infections other than pneumonia. Further studies are needed to better understand the complexities of immune regulation on infection and outcome after stroke. 相似文献85.
Quality of life before and after total laryngectomy: Results of a multicenter prospective cohort study 下载免费PDF全文
86.
87.
Mona Izadnegahdar Colleen Norris Padma Kaul Louise Pilote Karin H. Humphries 《The Canadian journal of cardiology》2014
This review aims to provide new insights into the basis for sex differences in acute coronary syndrome (ACS). Sex differences in mortality after ACS depend on age and the type of ACS, with the greatest gap being observed among younger adults and patients with ST-segment elevation myocardial infarction (STEMI). The sex gap diminishes with increasing age and does not appear to exist to the same extent among patients with non–STEMI or unstable angina. Although it is clear that younger women with acute myocardial infarction have higher mortality than do men in the short term; whether this difference is present in the long term remains unclear. Furthermore, women with ACS face delays in diagnosis and treatment, undergo less invasive management, have more bleeding complications, and receive less evidence-based medical therapy than do their male counterparts. Finally, women with ACS consistently report lower health-related quality of life than do men. To date, our understanding of the sex differences in ACS remains limited. The impact of biological factors and nonbiological factors (especially gender roles) need to be explored to elucidate the disparities in health outcomes between men and women. 相似文献
88.
89.
Michael V. Holmes Ruth Frikke-Schmidt Daniela Melis Robert Luben Folkert W. Asselbergs Jolanda M.A. Boer Jackie Cooper Jutta Palmen Pia Horvat Jorgen Engmann Ka-Wah Li N. Charlotte Onland-Moret Marten H. Hofker Meena Kumari Brendan J. Keating Jaroslav A. Hubacek Vera Adamkova Ruzena Kubinova Martin Bobak Kay-Tee Khaw Børge G. Nordestgaard Nick Wareham Steve E. Humphries Claudia Langenberg Anne Tybjaerg-Hansen Philippa J. Talmud 《Atherosclerosis》2014
Background
Conflicting evidence exists on whether smoking acts as an effect modifier of the association between APOE genotype and risk of coronary heart disease (CHD).Methods and results
We searched PubMed and EMBASE to June 11, 2013 for published studies reporting APOE genotype, smoking status and CHD events and added unpublished data from population cohorts. We tested for presence of effect modification by smoking status in the relationship between APOE genotype and risk of CHD using likelihood ratio test.In total 13 studies (including unpublished data from eight cohorts) with 10,134 CHD events in 130,004 individuals of European descent were identified. The odds ratio (OR) for CHD risk from APOE genotype (ε4 carriers versus non-carriers) was 1.06 (95% confidence interval (CI): 1.01, 1.12) and for smoking (present vs. past/never smokers) was OR 2.05 (95%CI: 1.95, 2.14). When the association between APOE genotype and CHD was stratified by smoking status, compared to non-ε4 carriers, ε4 carriers had an OR of 1.11 (95%CI: 1.02, 1.21) in 28,789 present smokers and an OR of 1.04 (95%CI 0.98, 1.10) in 101,215 previous/never smokers, with no evidence of effect modification (P-value for heterogeneity = 0.19). Analysis of pack years in individual participant data of >60,000 with adjustment for cardiovascular traits also failed to identify evidence of effect modification.Conclusions
In the largest analysis to date, we identified no evidence for effect modification by smoking status in the association between APOE genotype and risk of CHD. 相似文献90.
Edjair V. Cabral Leucio D. Vieira Bruna R. M. Sant'Helena Valdilene S. Ribeiro Juliane S. Farias Regina S. Aires Silvania T. Paz Humberto Muzi‐Filho Ana D. Paixo Adalberto Vieyra 《Clinical and experimental pharmacology & physiology》2019,46(12):1151-1165
Maternal salt overload programs cardiovascular and renal alterations in the offspring. However, beneficial and harmful effects of high dose vitamin E supplementation have been described in humans and animals. We investigated the hypothesis as to whether cardiac and renal alterations can be programmed by gestational salt overload, and can become further modified during lactation and after weaning. Male Wistar rats were used, being the offspring of mothers that drank either tap water or 0.3 mol/L NaCl for 20 days before and during pregnancy. α‐Tocopherol (0.35 g/kg) was administered to mothers daily during lactation or to their offspring for 3 weeks post‐weaning. Systolic blood pressure (tcSBP) was measured in juvenile rats aged 210 days. The response of mean arterial pressure (MAP) and heart rate (HR) to intravenous infusion of angiotensin II (Ang II) was also examined. Left ventricle plasma membrane (PMCA) and sarcoplasmic reticulum Ca2+‐ATPase (SERCA) activities, and certain parameters of renal function, were measured. Maternal saline programmed for increased body mass and kidney mass/body mass ratio, increased tcSBP, increased mean arterial pressure and heart rate with anomalous response to infused Ang II. In the heart, saline increased PMCA and α‐Tocopherol per se increased PMCA/SERCA. In the kidney, the most remarkable result was the silent saline programming of CrCl, which was sensitized for a sharp decrease after α‐Tocopherol. In conclusion, the combination of maternal saline overload and high α‐Tocopherol immediately after birth leads to simultaneous cardiovascular and renal alterations in the young offspring, like those encountered in type V cardiorenal syndrome. 相似文献