全文获取类型
收费全文 | 650篇 |
免费 | 33篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 25篇 |
儿科学 | 7篇 |
妇产科学 | 13篇 |
基础医学 | 99篇 |
口腔科学 | 18篇 |
临床医学 | 35篇 |
内科学 | 107篇 |
皮肤病学 | 12篇 |
神经病学 | 94篇 |
特种医学 | 29篇 |
外科学 | 69篇 |
预防医学 | 45篇 |
眼科学 | 2篇 |
药学 | 54篇 |
中国医学 | 1篇 |
肿瘤学 | 76篇 |
出版年
2022年 | 6篇 |
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 16篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 11篇 |
2015年 | 23篇 |
2014年 | 29篇 |
2013年 | 49篇 |
2012年 | 36篇 |
2011年 | 43篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 37篇 |
2007年 | 32篇 |
2006年 | 32篇 |
2005年 | 27篇 |
2004年 | 29篇 |
2003年 | 18篇 |
2002年 | 17篇 |
2001年 | 26篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 8篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 5篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1962年 | 1篇 |
排序方式: 共有686条查询结果,搜索用时 0 毫秒
61.
Overweight and obesity have reached epidemic dimensions worldwide, mainly due to consumption of high energy diets and increased sedentary behaviour. Overweight and insufficient physical activity are clearly associated with cardiovascular diseases and type 2 diabetes. Evidence is also accumulating that they may also increase cancer risk, particularly in the colon, breast and endometrium. This effect seems to be mediated by alterations in the metabolism of endogenous hormones, including sex steroids and insulin, and levels of insulin‐like growth factor(IGF)‐I and IGF‐binding proteins. In light of the beneficial effects of weight control and physical activity for cancer prevention, a healthy lifestyle, keeping a low body weight and exercising most days of the week, is recommended. 相似文献
62.
Giuseppe Mascellani Lino Liverani Agnese Prete Pier Angelo Guppola Gianluca Bergonzini Pietro Bianchini 《Thrombosis research》1994,74(6):605-615
Besides the major monosulphated disaccharide sequences (IdoA-GalNAc4SO3), dermatan sulphates (DS) contain the oversulphated sequences (IdoA2SO3-GalNAc4SO3) and (IdoA-GalNAc4,6SO3), the concentration of which is correlated with the HCII-mediated inhibition of thrombin by DS. The effect of the chemical removal of the sulphate groups on the HCII-mediated activity was studied. The base-catalyzed sulphate group displacement from IdoA2SO3 residues, leading to formation of the epoxyde aGulA, is a 1st order reaction. When the content of sequences (IdoA-GalNAc4,6SO3) is higher than that of sequences (IdoA2SO3-GalNAc4SO3), removal of the sulphate groups from Ido2SO3 reduces the HCII activity less than when the latter sequences prevail. (IdoA-GalNAc4,6SO3) cooperates with (IdoA2SO3-GalNAc4SO3) in the activation of the HCII. Also the removal of 6-SO3 groups from GalNAc4,6SO3, in absence of IdoA2SO3-GalNAc4SO3, considerably reduces the activity. A low molecular mass natural fraction rich in IdoA2SO3 as well as glucuronic acid, having higher electrophoretic mobility than the higher molecular mass DS which contains less glucuronic acid, is remarkably active. 相似文献
63.
Danusa Leidens Adalto Bianchini Antonio Sergio Varela Junior Indianara Fernanda Barcarolli Carlos Eduardo Rosa Josiane Bonnel Cecilia Perez Calabuig Carine Dahl Corcini 《Bulletin of environmental contamination and toxicology》2018,100(3):324-330
Lead (Pb) effects on testis histology, as well as sperm quality and oxidative status were evaluated in male Chestnut Capped Blackbird (Chrysomus ruficapillus). Wild blackbirds were captured, immediately sampled (field group) or kept in captivity and treated with a single intraperitoneal injection of saline solution (control) or saline solution with Pb acetate (50 or 100 mg/kg Pb). Seven days after injection, whole blood, ductus deferens and testis samples were collected. Increased Pb concentrations were observed in whole blood and testis of Pb-exposed blackbirds with respect to those from field and control blackbirds. Sperm cells of Pb-exposed blackbirds showed loss of membrane integrity, mitochondrial functionality, and DNA integrity. Also, oxidative damage was observed in testis of blackbirds injected with 100 mg/kg Pb. These findings indicate that Pb is accumulated in testis of C. ruficapillus, inducing severe morphological and biochemical injury that can compromise the reproductive performance of male blackbirds. Although the exposure scenario (Pb acetate, high dosage and intraperitoneal injection) tested in the present study would likely not occur in the wild, it was adequate to show potential and relevant toxic effects of Pb in wild birds. 相似文献
64.
Pedroso MS Bersano JG Bianchini A 《Environmental toxicology and chemistry / SETAC》2007,26(10):2158-2165
The euryhaline copepod Acartia tonsa was exposed to silver (AgNO(3)) in either the absence or the presence of food (diatom Thalassiosira weissflogii; 2 x 10(4) cells/ml). Standard static-renewal toxicity tests that included a fixed photoperiod of 16: 8 h light:dark and temperature (20 degrees C) were run in three different salinities (5, 15, and 30 ppt) together with measurements of pH, ions (Na(+), Cl(-), K(+), SO(4)(2-), Mg(2+), and Ca(2+)), alkalinity, dissolved organic carbon, and total and dissolved (0.45 microm) silver concentrations in the experimental media. In the absence of food, the 48-h EC50 (concentration causing effect to 50% of the individuals tested) values based on total and dissolved silver concentrations were 11.6, 87.2, and 163.2 microg Ag/L and 7.1, 79.2, and 154.6 microg Ag/L at salinities 5, 15, and 30 ppt, respectively. In the presence of food, they were 62.1, 98.5, and 238.4 microg Ag/L and 48.4, 52.3, and 190.9 microg Ag/L, respectively. In all experimental conditions, most of the toxic silver fraction was in the dissolved phase, regardless of salinity or the presence of food in the water. In either the absence or the presence of food, acute silver toxicity was salinity dependent, decreasing as salinity increased. Data indicate that changes in water chemistry can account for the differences in acute silver toxicity in the absence of food, but not in the presence of food, suggesting that A. tonsa requires extra energy to cope with the stressful conditions imposed by acute silver exposure and ionoregulatory requirements in low salinities. These findings indicate the need for incorporation of both salinity and food (organic carbon) in a future biotic ligand model (BLM) version for estuarine and marine conditions, which could be validated and calibrated using the euryhaline copepod A. tonsa. 相似文献
65.
66.
Lithium modulates the production of peripheral and cerebral cytokines in an animal model of mania induced by dextroamphetamine 下载免费PDF全文
67.
Giorgio Grani Mimma D’Alessandri Giovanni Carbotta Angela Nesca Marianna Del Sordo Stefania Alessandrini Carmela Coccaro Roberta Rendina Marta Bianchini Natalie Prinzi Angela Fumarola 《Medicine》2015,94(27)
Ultrasonography is the main imaging method for the workup of thyroid nodules. However, interobserver agreement reported for echogenicity and echotexture is quite low. The aim of this study was to perform quantitative measurements of the degree of echogenicity and heterogeneity of thyroid nodules, to develop an objective and reproducible method to stratify these features to predict malignancy.A retrospective study of patients undergoing ultrasonography-guided fine-needle aspiration was performed in an University hospital thyroid center. From January 2010 to October 2012, 839 consecutive patients (908 nodules) underwent US-guided fine-needle aspiration. In a single ultrasound image, 3 regions of interest (ROIs) were drawn: the first including the nodule; the second including a portion of the adjacent thyroid parenchyma; the third, the strap muscle. Histogram analysis was performed, expressing the median, mean, and SD of the gray levels of the pixels comprising each region. Echogenicity was expressed as a ratio: the nodule/parenchyma, the nodule/muscle, and parenchyma/muscle median gray ratios were calculated. The heterogeneity index (HI) was calculated as the coefficient of variation of gray histogram for each of the 3 ROIs. Cytology and histology reports were recorded.Nodule/parenchyma median gray ratio was significantly lower (more hypoechoic) in nodules found to be malignant (0.45 vs 0.61; P = 0.002) and can be used as a continuous measure of hypoechogenicity (odds ratio [OR] 0.12; 95% confidence interval [CI] 0.03–0.49). Using a cutoff derived from ROC curve analysis (<0.46), it showed a substantial inter-rater agreement (k = 0.74), sensitivity of 56.7% (95% CI 37.4–74.5%), specificity of 72.0% (67.8–75.9%), positive likelihood ratio (LR) of 2.023 (1.434–2.852), and negative LR of 0.602 (0.398–0.910) in predicting malignancy (diagnostic odds ratio 3.36; 1.59–7.10). Parenchymal HI was associated with anti-thyroperoxidase positivity (OR 19.69; 3.69–105.23). The nodule HI was significantly higher in malignant nodules (0.73 vs 0.63; P = 0.03) and, if above the 0.60 cutoff, showed sensitivity of 76.7% (57.7–90.1%), specificity of 46.8% (42.3–51.4%), positive LR of 1.442 (1.164–1.786), and negative LR of 0.498 (0.259–0.960).Evaluation of nodule echogenicity and echotexture according to a numerical estimate (nodule/parenchyma median gray ratio and nodule HI) allows for an objective stratification of nodule echogenicity and internal structure. 相似文献
68.
Susanna Esposito Paola Marchisio Annalisa Orenti Silvia Spena Sonia Bianchini Erica Nazzari Chiara Rosazza Alberto Zampiero Elia Biganzoli Nicola Principi 《Medicine》2015,94(42)
Evaluation of the genetic contribution to the development of recurrent acute otitis media (rAOM) remains challenging. This study aimed to evaluate the potential association between single nucleotide polymorphisms (SNPs) in selected genes and rAOM and to analyze whether genetic variations might predispose to the development of complicated recurrent cases, such as those with tympanic membrane perforation (TMP).A total of 33 candidate genes and 47 SNPs were genotyped in 200 children with rAOM (116 with a history of TMP) and in 200 healthy controls.INFγ rs 12369470CT was significantly less common in the children with rAOM than in healthy controls (odds ratio [OR] 0.5, 95% confidence interval [CI] 0.25–1, P = 0.04). Although not significant, interleukin (IL)-1β rs 1143627G and toll-like receptor (TLR)-4 rs2737191AG were less frequently detected in the children with rAOM than in controls. The opposite was true for IL-8 rs2227306CT, which was found more frequently in the children with rAOM than in healthy controls. The IL-10 rs1800896TC SNP and the IL-1α rs6746923A and AG SNPs were significantly more and less common, respectively, among children without a history of TMP than among those who suffered from this complication (OR 2.17, 95% CI 1.09–4.41, P = 0.02, and OR 0.42, 95% CI 0.21–0.84, P = 0.01).This study is the first report suggesting an association between variants in genes encoding for factors of innate or adaptive immunity and the occurrence of rAOM with or without TMP, which confirms the role of genetics in conditioning susceptibility to AOM. 相似文献
69.
Pledget-assisted hemostasis to fix residual access-site bleedings after double pre-closure technique
70.
The aims of this study were to: (a) examine the consistency of the published Wisconsin Card Sorting Test (WCST) factor structures; (b) determine the factor structure of the WCST in a large, heterogeneous sample; and (c) compare the WCST factor analytically with other neuropsychological procedures. Two WCST factors (concept formation/perseveration and Failure-to-Maintain-Set [FMS]) were consistently reported in the literature. Our analysis of data from 473 clinical cases replicated the two factors previously reported and revealed a third on which nonperseverative errors (NPE) was the sole salient variable. This pattern was maintained in three of four diagnostically distinct subgroups. These factors are potentially clinically meaningful, with each seeming to reflect one of three qualitatively different performance styles. In the construct validation factor analysis, WCST scores loaded independently of other neuropsychological variables, indicating that the WCST contributes uniquely to neuropsychological evaluation. Nevertheless, despite the rational interpretation of the factors, the cognitive processes underlying WCST performance remain poorly understood. Future directions for the application of these factor analytic findings are discussed. 相似文献