全文获取类型
收费全文 | 1767篇 |
免费 | 125篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 94篇 |
妇产科学 | 48篇 |
基础医学 | 267篇 |
口腔科学 | 18篇 |
临床医学 | 199篇 |
内科学 | 346篇 |
皮肤病学 | 11篇 |
神经病学 | 189篇 |
特种医学 | 57篇 |
外科学 | 221篇 |
综合类 | 6篇 |
预防医学 | 159篇 |
眼科学 | 10篇 |
药学 | 172篇 |
中国医学 | 1篇 |
肿瘤学 | 90篇 |
出版年
2023年 | 11篇 |
2022年 | 27篇 |
2021年 | 47篇 |
2020年 | 25篇 |
2019年 | 42篇 |
2018年 | 33篇 |
2017年 | 46篇 |
2016年 | 57篇 |
2015年 | 46篇 |
2014年 | 56篇 |
2013年 | 79篇 |
2012年 | 112篇 |
2011年 | 133篇 |
2010年 | 86篇 |
2009年 | 86篇 |
2008年 | 105篇 |
2007年 | 105篇 |
2006年 | 126篇 |
2005年 | 127篇 |
2004年 | 113篇 |
2003年 | 108篇 |
2002年 | 107篇 |
2001年 | 16篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1970年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有1897条查询结果,搜索用时 0 毫秒
81.
Human longevity is an extremely complex trait with various genetic, epigenetic and environmental factors acting upon the longevity phenotype. It is now becoming evident that whilst the genetic differences contribute only modestly to life expectancy before the age of 60 years, their impact on survival becomes more prominent at the extreme ages. Several longevity gene candidates have emerged during the past decade; the majority of them are related either to inflammatory functions, stress response or to lipid and glucose metabolism. The variants of inflammatory and immune response genes are of special interest since advancing ages is accompanied by a decline in several immune functions—a phenomenon called immunosenescence. Paradoxically, ageing is also characterised by chronic low-grade inflammation termed “inflammaging”, which manifests as a two- to fourfold increase in the production of proinflammatory cytokines and acute phase proteins. These contrasting phenomena provide a functional rationale of how the genetic differences in inflammatory mediators may modify the life span of the elderly. Besides describing the pre-existing inflammatory and immune-related longevity gene variants, in this review, we also explain some of the theoretical and practical challenges that genetic longevity studies often encounter. 相似文献
82.
83.
Proteomic-Based Detection of a Protein Cluster Dysregulated during Cardiovascular Development Identifies Biomarkers of Congenital Heart Defects
下载免费PDF全文
![点击此处可从《PLoS Clinical Trials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
84.
Tuija H. Nieminen Nora M. Hagelberg Teijo I. Saari Mikko Neuvonen Kari Laine Pertti J. Neuvonen Klaus T. Olkkola 《European Journal of Pain》2010,14(8):854-859
Background: Chronic pain is associated with depression. Self‐treatment of depression with herbal over‐the‐counter medicine St John's wort makes pain patients prone to drug interactions. Aims: The aim of this study was to assess the potential of St John's wort to alter the CYP3A‐mediated metabolism of a μ‐opioid receptor agonist, oxycodone. Methods: The study design was placebo‐controlled, randomized, cross‐over with two phases at intervals of 4 weeks and was conducted with 12 healthy participants. St John's wort (Jarsin®) or placebo was administered t.i.d. for 15 days and oral oxycodone hydrochloride 15 mg on day 14. Oxycodone pharmacokinetics and pharmacodynamics were compared after St John's wort or placebo. Behavioural and analgesic effects were assessed with subjective visual analogue scales and cold pressor test. Plasma drug concentrations were measured from 0 to 48 h, behavioural and analgesic effects from 0 to 12 h. Results: Following St John's wort administration the oxycodone AUC decreased 50% (p < 0.001). Oxycodone elimination half‐life shortened from a mean ± SD 3.8 ± 0.7 to 3.0 ± 0.4 h (p < 0.001). The self‐reported drug effect of oxycodone as measured by AUEC0–12 decreased significantly (p = 0.004). Differences between St John's wort and placebo phases in cold pain threshold and intensity AUEC0–12 were not observed. Conclusions: St John's wort greatly reduced the plasma concentrations of oral oxycodone. The self‐reported drug effect of oxycodone decreased significantly. This interaction may potentially be of some clinical significance when treating patients with chronic pain. 相似文献
85.
86.
Juha P. Ahtiainen Merja Hoffren Juha J. Hulmi Mikko Pietikäinen Antti A. Mero Janne Avela Keijo Häkkinen 《European journal of applied physiology》2010,108(2):273-279
The purpose of this study was to examine the reliability and validity of the “panoramic” brightness mode ultrasonography (US)
method to detect training-induced changes in muscle cross-sectional area (CSA) by comparison with results obtained using magnetic
resonance imaging (MRI). Out of 27 young male volunteers, 20 subjects were assigned to training group and seven to non-training
control group. Muscle CSAs of vastus lateralis were analyzed by MRI and US before and after 21 weeks of either heavy resistance
training or control period. Measured by both the US and MRI, the resistance training induced significant increases (~13–14%,
P < 0.001) in muscle CSA, whereas no changes were observed in control group. A high repeatability was found between the two
consequent US measurements (intraclass correlation coefficient, ICC of 0.997) with standard error of measurement (SEM) of
0.38 cm2 and smallest detectable difference of 1.1 cm2. Validity of the US method against MRI in assessing CSA of VL produced ICC of 0.905 and SEM of 0.87 cm2 with high limits of agreement analyzed by Bland and Altman method. However, the MRI produced systematically (10 ± 4%, P < 0.01) larger CSA values than the US method. The US showed high agreement against MRI in detecting changes in muscle CSA
(ICC of 0.929, SEM of 0.94 cm2). The results of this study showed that the panoramic US method provides repeatable measures of a muscle CSA although MRI
produced larger absolute CSA values. Moreover, this US method detects training-induced changes in muscle CSA with a comparable
degree of precision to MRI. 相似文献
87.
Klas Linderborg Jean Pierre Joly Jukka-Pekka Visapää Mikko Salaspuro 《Food and chemical toxicology》2008
The old Normandian habit of consumption of hot Calvados is associated with an increased risk of oesophageal cancer compared to other alcoholic beverages. The role of alcohol consumption in the risk of oesophageal cancer is well established. The first metabolite of alcohol, acetaldehyde is a potential local carcinogen in humans. Accordingly, different acetaldehyde concentrations in different beverages could account for some of the variations in cancer risk with regard to the type of alcoholic beverage. Eighteen samples of farm-made Calvados were collected in Normandy. Samples of commercially available beverages were purchased, including factory-made Calvados, other spirits, wines, beer and cider. The samples were analysed gas-chromatically for acetaldehyde and ethanol concentrations. All results are expressed as mean ± SD. The mean acetaldehyde concentration of all Calvados samples (1781 ± 861 μM, n = 25) differed highly significantly (p < 0.001) from that of all wine samples (275 ± 236 μM), from all other spirits samples (1251 ± 1155 μM, p < 0.05), and from all beer and cider samples (233 ± 281 μM, p < 0.001). Farm-made Calvados and farm-made cognac had the highest mean acetaldehyde concentration of the measured beverages. The high concentration of acetaldehyde combined with possible effects of the high temperature at which Calvados is consumed could account for the increased risk of Calvados-related oesophageal cancer. 相似文献
88.
Mikko Tenhunen Juhani Collan Mauri Kouri Aki Kangasmki Jorma Heikkonen Kalevi Kairemo Antti Mkitie Heikki Joensuu Kauko Saarilahti 《Radiotherapy and oncology》2008,87(2):260-267
BACKGROUND AND PURPOSE: To evaluate salivary gland scintigraphy in prediction of salivary flow following radiation therapy. PATIENTS AND METHODS: Twenty patients diagnosed with head and neck cancer were treated with intensity modulated radiation therapy with an intention to spare the salivary gland function. The total quantitative saliva secretion was measured prior to and 6 and 12 months after therapy, and the function of the major salivary glands was monitored using Tc-99m-pertechnetate scintigraphy. Two models were designed for prediction of the post-treatment salivary flow: an average model, based on the average proportions of saliva produced by each of the four major glands in healthy subjects, and an individual model, based on saliva produced by each gland as measured by scintigraphy prior to therapy. These models were compared with volume-based (Lyman) normal tissue complication probability models using two published sets of model parameters. RESULTS: The D(50) for the parotid and the submandibular gland function assessed at 6 and 12 months after radiotherapy was approximately 39Gy. The scintigraphy-based individual model predicted well the measured post-treatment saliva flow rates. The correlation coefficient between the predicted stimulated and the measured saliva flow rate was 0.77 (p<0.0001) at 6 months and 0.55 (p=0.034) at 12 months after completion of radiotherapy. The relative changes in unstimulated and stimulated salivary flow rates showed similar dependency on the cumulative radiation dose. CONCLUSIONS: Salivary gland function assessed by scintigraphy prior to radiotherapy is useful in prediction of the residual salivary flow after radiotherapy. 相似文献
89.
Sampsa Matikainln Mikko Hurme 《International journal of cancer. Journal international du cancer》1994,57(1):98-103
Several human myeloid leukemia cell lines growing in vitro can be induced to differentiate to more mature monocyteJ. macrophage-like cells by treatment with protein kinase C-activating phorbol esters, such as PMA. In addition to PMA, cells of the THP-I myeloid leukemia cell line acquire macro-phage-like characteristics after treatment with all-trans retinoic acid (RA). To analyze the signal transduction mechanisms induced by RA, we first compared the effects of PMA and RA on the expression of genes which are known to be regulated during monocytic differentiation. Both RA and PMA effectively down-regulated c-myc expression, while c-myb expression decreased only after PMA treatment. Expression of the β2-integrin genes. CDIIa and CDIIb, was clearly increased after both of these treatments. Their effects on the src-family tyrosine kinase genes were different: hck expression was similarly induced by these agents but lyn expression was stronger and more rapid after RA treatment. RA also enhanced lyn mRNA production rapidly in HL-60, indicating that the activation of lyn gene expression is common in monocytic and granulocytic maturation of myeloid leukemia cells. To examine whether the AP-1 enhancer activity is involved in RA-induced monocytic differentiation, THP-1 cells were transiently transfected with a chloramphenicol acetyi transferase (CAT)-reporter gene containing S copies of the AP-1 binding sites. In contrast to PMA, RA did not induce any CAT activity in these cells, thus suggesting that the RA-induced changes in the expression of those genes described above were not dependent on the AP-1 enhancer activity. © Wiley-Liss, Inc. 相似文献
90.
Zidi SH Linderborg K Väkeväinen S Salaspuro M Jokelainen K 《Alcoholism, clinical and experimental research》2003,27(9):1459-1462
BACKGROUND: Normal colonic bacteria possessing alcohol dehydrogenase activity can oxidize ethanol to acetaldehyde. Acetaldehyde recently has been shown to be a local carcinogen in humans. The aim of the study was to examine the effect of lactulose feeding on fecal and cecal pH, intracolonic acetaldehyde concentration, and total ethanol elimination rate in rats. METHODS: Sixty Wistar rats were divided into four groups. Groups 2 and 4 received lactulose daily (11 g/kg body weight for 14 days). On days 7 and 14, groups 1 and 2 received ethanol (1.5 g/kg body weight) intraperitoneally, whereas groups 3 and 4 received saline. RESULTS: Fecal and cecal pH values decreased significantly after lactulose treatment compared with the controls. Lactulose feeding reduced the total ethanol elimination rate by 13.8% (257 +/- 0.008 mg/kg/hr vs. 298 +/- 0.003 mg/kg/hr, p < 0.001) and the intracecal acetaldehyde concentration by 66.2% after ethanol (49 +/- 29 microM vs. 145 +/- 47 microM, p = 0.03) compared with the controls. CONCLUSION: Lactulose feeding to rats significantly reduces ethanol elimination rate and intraluminal acetaldehyde concentration in the colon after ethanol administration. This prebiotic thus could be used as an effective agent to block the microbial production of carcinogenic acetaldehyde in the large intestine. 相似文献