全文获取类型
收费全文 | 1324篇 |
免费 | 107篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 6篇 |
妇产科学 | 18篇 |
基础医学 | 102篇 |
口腔科学 | 28篇 |
临床医学 | 37篇 |
内科学 | 287篇 |
皮肤病学 | 3篇 |
神经病学 | 56篇 |
特种医学 | 13篇 |
外科学 | 38篇 |
综合类 | 53篇 |
预防医学 | 233篇 |
眼科学 | 6篇 |
药学 | 437篇 |
中国医学 | 10篇 |
肿瘤学 | 113篇 |
出版年
2023年 | 10篇 |
2022年 | 18篇 |
2021年 | 31篇 |
2020年 | 40篇 |
2019年 | 34篇 |
2018年 | 26篇 |
2017年 | 61篇 |
2016年 | 51篇 |
2015年 | 40篇 |
2014年 | 86篇 |
2013年 | 129篇 |
2012年 | 48篇 |
2011年 | 83篇 |
2010年 | 79篇 |
2009年 | 77篇 |
2008年 | 86篇 |
2007年 | 78篇 |
2006年 | 61篇 |
2005年 | 40篇 |
2004年 | 34篇 |
2003年 | 33篇 |
2002年 | 26篇 |
2001年 | 22篇 |
2000年 | 18篇 |
1999年 | 23篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 16篇 |
1993年 | 12篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有1445条查询结果,搜索用时 15 毫秒
1.
《Journal of thoracic oncology》2019,14(8):1360-1369
IntroductionInherited susceptibility to lung cancer risk in never-smokers is poorly understood. The major reason for this gap in knowledge is that this disease is relatively uncommon (except in Asians), making it difficult to assemble an adequate study sample. In this study we conducted a genome-wide association study on the largest, to date, set of European-descent never-smokers with lung cancer.MethodsWe conducted a two-phase (discovery and replication) genome-wide association study in never-smokers of European descent. We further augmented the sample by performing a meta-analysis with never-smokers from the recent OncoArray study, which resulted in a total of 3636 cases and 6295 controls. We also compare our findings with those in smokers with lung cancer.ResultsWe detected three genome-wide statistically significant single nucleotide polymorphisms rs31490 (odds ratio [OR]: 0.769, 95% confidence interval [CI]: 0.722–0.820; p value 5.31 × 10-16), rs380286 (OR: 0.770, 95% CI: 0.723–0.820; p value 4.32 × 10-16), and rs4975616 (OR: 0.778, 95% CI: 0.730–0.829; p value 1.04 × 10-14). All three mapped to Chromosome 5 CLPTM1L-TERT region, previously shown to be associated with lung cancer risk in smokers and in never-smoker Asian women, and risk of other cancers including breast, ovarian, colorectal, and prostate.ConclusionsWe found that genetic susceptibility to lung cancer in never-smokers is associated to genetic variants with pan-cancer risk effects. The comparison with smokers shows that top variants previously shown to be associated with lung cancer risk only confer risk in the presence of tobacco exposure, underscoring the importance of gene-environment interactions in the etiology of this disease. 相似文献
2.
3.
4.
Summary The prevalence of smoking, hypertension and diabetes mellitus was assessed in 221 patients suffering from internal carotid stenosis and compared with the prevalences in two sex- and age-matched control groups composed of subjects having normal Doppler findings and from non-neurological outpatients. Of the subjects with carotid stenosis 27.6% were hypertensive smokers in comparison with 9.5% and 17.2% in the two control groups. The difference of the stenosis cohort from the two control groups was significant (P<0.01 and P=0.016 respectively). There was no statistically significant differences between the occurrence of diabetes and hypertension in non-smokers and patients who smoked. In 394 investigated patients suffering from carotid stenosis or occlusion an obstruction index, based on the Doppler shift frequency, was calculated. This index was lowest in the normotentive non-smokers. It was only insignificantly higher in the hypertensive non-smokers but significantly so in the normotensive smokers. The index was highest in the hypertensive non-smokers. It was concluded that cigarette smoking, especially if associated with hypertension, is a determinant risk factor for carotid stenosis and occlusion. 相似文献
5.
6.
R. Bendayan G. Kennedy R. C. Frecker E. M. Sellers 《European journal of clinical pharmacology》1993,44(1):51-55
Summary The efficacy of cimetidine as a treatment that could reduce smoking in heavily dependent smokers has been determined. In a randomised, double-blind, double-crossover experiment, 43 heavy smokers were divided into two groups, one receiving cimetidine 400 mg orally three times a day, and the other receiving placebo for two weeks followed by the alternative treatment (placebo or cimetidine).No significant difference in the mean alveolar carbon monoxide, nicotine or cotinine levels was found between the two treatment groups compared to baseline. Since the alveolar carbon monoxide level reflects the intensity of smoking behaviour, the results suggest that no change in smoking behaviour occurred in the subjects.Contrary to our previous findings that cimetidine decreased the total body clearance of nicotine by 30% in a population of non-smokers, in the heavily dependent smokers, cimetidine did not appear to alter nicotine elimination. One possible explanation for the discrepancy is that tobacco smoking is known to induce nicotine metabolism and the induction might have offset any effect of cimetidine on nicotine elimination.Cimetidine does not appear to be a useful treatment leading to a reduction or cessation of cigarette smoking. 相似文献
7.
100mg香烟烟油,多氯联苯诱导大鼠肝S_9组分中芳香烃羟化酶代谢B[a]P为3-OH-B[a]P的活性分别升高约40,20倍,而代谢B[a] P生成6-OXY-B [a]P自由基产物却仅由多氯联苯诱导的S_9组分作用中才被观察到。 相似文献
8.
Yuan Xue Tracy L. Williams Ting Li Joshua Umbehr Liang Fang Weiqun Wang Richard C. Baybutt 《Toxicology in vitro》2005,19(8):1061-1069
This study was to evaluate the effects of cigarette smoke constituents upon type II pneumocyte surfactant production in vitro, and how vitamins A and E may alter the response. Freshly isolated type II pneumocytes from Sprague–Dawley rats were incubated 20 h in medium with fetal bovine serum that was or was not treated with cigarette smoke. The number of adherent cells was inversely related to the dose of smoke or benzo(a)pyrene. Despite the decreased number of treated cells, the total amount of surfactant per culture well was unchanged, whereas surfactant production per cell was significantly increased (P < 0.05). Vitamin A concentration was significantly (P < 0.05) lower in the smoke-treated serum compared with untreated serum. When vitamin A or E was added to the cigarette smoke-treated serum, cell adherence and surfactant production returned to control values. In conclusion, cigarette smoke constituents or benzo(a)pyrene alone decreased the number of adherent type II pneumocytes, but did not alter surfactant amounts because of an increased production of surfactant per cell. Type II pneumocytes seem to adjust surfactant production dependent upon the number of type II pneumocytes to produce it and vitamin A or E enhance cell attachment in the presence of the smoke toxins. 相似文献
9.
G. Sutherland M. A. H. Russell J. Stapleton C. Feyerabend O. Ferno 《Psychopharmacology》1992,108(4):512-518
Plasma nicotine concentrations following administration by two types of nasal nicotine spray were compared in ten subjects. Absorption was particularly rapid during the first 2.5 min, the average rise in blood nicotine concentrations during this time being 8.6 ng/ml for the two products, followed by a small further rise to an average peak increase of 10.5 ng/ml 5 min after the dose of 2 mg nicotine base (mean 27.8 micrograms/kg). Despite a four-fold Cmax variation between subjects, the levels of individual subjects were fairly consistent across the two products. There were no significant differences between the two products in blood nicotine concentrations or cardiovascular responses, and the correlation between the AUCs from the two products was 0.68 (P = 0.01). Eight subjects reported subjective feelings of light-headedness or slight dizziness, which are not typical after slower absorption from nicotine gum or skin patches. Blood nicotine levels within the smoking range were soon built up with repeated doses, even in the subject with the least efficient nasal absorption. In a second study of ad libitum use under clinical conditions both products appeared sufficiently acceptable for therapeutic use as an aid to smoking cessation. There was no tendency to escalate to excessive use over 4 weeks, and blood nicotine concentrations in nine subjects averaged only 44% of their prior smoking levels. Only one subject had levels equivalent to prior smoking and possible reasons why this was not more common are discussed. 相似文献
10.
实验研究表明,氧化剂氯胺T、过氧化氢可抑制人血清抗弹性酶的能力。新鲜烟液可抑制人、犬、兔血清对弹性酶的抑制能力,人血清对烟液的敏感性大于犬和免。从而提示,吸烟是肺气肿的病因之一。 相似文献