全文获取类型
收费全文 | 1177篇 |
免费 | 95篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 33篇 |
妇产科学 | 38篇 |
基础医学 | 112篇 |
口腔科学 | 13篇 |
临床医学 | 116篇 |
内科学 | 192篇 |
皮肤病学 | 11篇 |
神经病学 | 142篇 |
特种医学 | 113篇 |
外科学 | 170篇 |
综合类 | 46篇 |
预防医学 | 94篇 |
眼科学 | 12篇 |
药学 | 64篇 |
中国医学 | 1篇 |
肿瘤学 | 118篇 |
出版年
2023年 | 15篇 |
2021年 | 12篇 |
2020年 | 18篇 |
2019年 | 22篇 |
2018年 | 20篇 |
2017年 | 27篇 |
2016年 | 24篇 |
2015年 | 27篇 |
2014年 | 33篇 |
2013年 | 55篇 |
2012年 | 55篇 |
2011年 | 40篇 |
2010年 | 49篇 |
2009年 | 41篇 |
2008年 | 39篇 |
2007年 | 42篇 |
2006年 | 66篇 |
2005年 | 37篇 |
2004年 | 67篇 |
2003年 | 40篇 |
2002年 | 30篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 23篇 |
1998年 | 28篇 |
1997年 | 31篇 |
1996年 | 30篇 |
1995年 | 34篇 |
1994年 | 18篇 |
1993年 | 13篇 |
1992年 | 23篇 |
1991年 | 19篇 |
1990年 | 19篇 |
1989年 | 28篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 21篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1983年 | 15篇 |
1982年 | 5篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1978年 | 21篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1974年 | 4篇 |
1968年 | 4篇 |
1963年 | 4篇 |
排序方式: 共有1278条查询结果,搜索用时 15 毫秒
51.
Ishiguro A; Spirin KS; Shiohara M; Tobler A; Gombart AF; Israel MA; Norton JD; Koeffler HP 《Blood》1996,87(12):5225-5231
52.
Tina Harmer Lassen Hanne Frederiksen Tina Kold Jensen J?rgen Holm Petersen Ulla N. Joensen Katharina M. Main Niels E. Skakkebaek Anders Juul Niels J?rgensen Anna-Maria Andersson 《Environmental health perspectives》2014,122(5):478-484
Background: Few human studies have examined bisphenol A (BPA) exposure in relation to semen quality and reproductive hormones in men, and results are divergent.Objectives: We examined associations between urinary BPA concentration and reproductive hormones, as well as semen quality, in young men from the general population.Methods: Our study population consisted of 308 young men from the general population. Urinary BPA concentration was measured by isotope dilution TurboFlow-liquid chromatography–tandem mass spectrometry. We used multiple linear regression analysis to estimate associations between BPA concentration and reproductive hormones and semen quality, adjusting for confounding factors.Results: We found that 98% of the men had detectable urinary levels of BPA. Median (5th–95th percentiles) BPA concentration was 3.25 ng/mL (0.59–14.89 ng/mL). Men with BPA concentrations above the lowest quartile had higher concentrations of serum testosterone, luteinizing hormone (LH), estradiol, and free testosterone compared with the lowest quartile (ptrend ≤ 0.02). Men in the highest quartile of BPA excretion had on average 18% higher total testosterone (95% CI: 8, 28%), 22% higher LH (95% CI: 6, 39%), and 13% higher estradiol (95% CI: 4, 24%) compared with lowest quartile. Men in the highest quartile of BPA also had significantly lower percentage progressive motile spermatozoa compared with men in the lowest quartile (–6.7 percentage points, 95% CI: –11.76, –1.63). BPA was not associated with other semen parameters. Adjusting for dietary patterns did not influence the results.Conclusions: The pattern of associations between BPA and reproductive hormones could indicate an antiandrogenic or antiestrogenic effect, or both, of BPA on the hypothalamic–pituitary–gonadal hormone feedback system, possibly through a competitive inhibition at the receptor level. However, additional research is needed to confirm our findings and to further test the suggested potential mechanisms.Citation: Lassen TH, Frederiksen H, Jensen TK, Petersen JH, Joensen UN, Main KM, Skakkebaek NE, Juul A, Jørgensen N, Andersson AM. 2014. Urinary bisphenol A levels in young men: association with reproductive hormones and semen quality. Environ Health Perspect 122:478–484; http://dx.doi.org/10.1289/ehp.1307309 相似文献
53.
Tjalf Ziemssen Ovidiu A. Bajenaru Adriana Carrá Nina de Klippel João C. de Sá Astrid Edland Jette L. Frederiksen Olivier Heinzlef Klimentini E. Karageorgiou Rafael H. Lander Delgado Anne-Marie Landtblom Miguel A. Macías Islas Niall Tubridy Yossi Gilgun-Sherki 《Journal of neurology》2014,261(11):2101-2111
Studies suggest that patients with relapsing-remitting multiple sclerosis (RRMS) who do not benefit from other disease-modifying treatments (DMTs) may benefit from converting to glatiramer acetate (GA). COPTIMIZE was a 24-month observational study designed to assess the disease course of patients converting to GA 20 mg daily from another DMT. Eligible patients had converted to GA and had received prior DMT for 3–6 months, depending on the reasons for conversion. Patients were assessed at baseline and at 6, 12, 18, and 24 months. In total, 672 patients from 148 centers worldwide were included in the analysis. Change of therapy to GA was prompted primarily by lack of efficacy (53.6 %) or intolerable adverse events (AEs; 44.8 %). Over a 24-month period, 72.7 % of patients were relapse free. Mean annual relapse rate decreased from 0.86 [95 % confidence interval (CI) 0.81–0.91] before the change to 0.32 (95 % CI 0.26–0.40; p < 0.0001) at last observation, while the progression of disability was halted, as the Kurtzke Expanded Disability Status Scale (EDSS) scores remained stable. Patients improved significantly (p < 0.05) on measures of fatigue, quality of life, depression, and cognition; mobility scores remained stable. The results indicate that changing RRMS patients to GA is associated with positive treatment outcomes. 相似文献
54.
Spread of X inactivation on chromosome 15 is associated with a more severe phenotype in a girl with an unbalanced t(X; 15) translocation
下载免费PDF全文
![点击此处可从《American journal of medical genetics. Part A》网站下载免费的PDF全文](/ch/ext_images/free.gif)
55.
56.
C. Frederiksen J. Lykke Ib J. Christensen N. Brünner H. J. Nielsen 《Scandinavian journal of clinical and laboratory investigation》2013,73(5):545-552
Objective. Tissue inhibitor of metalloproteinase‐1 (TIMP‐1) plays a major role in the regulation of tissue growth, including cancer growth. The TIMP‐1 protein can be determined in plasma, and increased plasma levels of TIMP‐1 are associated with a poor prognosis of colorectal cancer patients. The aim of the present study was to evaluate whether tumour tissue release of the TIMP‐1 protein contributes to the increased plasma levels of TIMP‐1 observed in patients with colorectal cancer. Material and methods. Preoperative blood samples from a peripheral vein and intraoperative blood samples from a tumour artery, a tumour vein and from a peripheral vein were drawn from 24 patients undergoing elective, intended curative surgery for primary rectal cancer. TIMP‐1 levels were determined concurrently in plasma from all samples using a validated ELISA method. Counts of white blood cells and platelets were also carried out. Results. No significant differences between plasma TIMP‐1 levels could be demonstrated in any compartment. In particular, there was no significant difference in TIMP‐1 levels in plasma from tumour arteries and tumour veins. However, there was a significant decrease in neutrophil cell counts from tumour arteries to tumour veins (p<0.001). Conclusions. The present results do not support the current hypothesis that tumour cells contribute substantially to increased plasma TIMP‐1 levels observed in patients with colorectal cancer. 相似文献
57.
58.
Lisa J Frederiksen Richard Sullivan Lori R Maxwell Shannyn K Macdonald-Goodfellow Michael A Adams Brian M Bennett D Robert Siemens Charles H Graham 《Clinical cancer research》2007,13(7):2199-2206
PURPOSE: Hypoxia contributes to drug resistance in solid cancers, and studies have revealed that low concentrations of nitric oxide (NO) mimetics attenuate hypoxia-induced drug resistance in tumor cells in vitro. Classic NO signaling involves activation of soluble guanylyl cyclase, generation of cyclic GMP (cGMP), and activation of cGMP-dependent protein kinase. Here, we determined whether chemosensitization by NO mimetics requires cGMP-dependent signaling and whether low concentrations of NO mimetics can chemosensitize tumors in vivo. EXPERIMENTAL DESIGN: Survival of human prostate and breast cancer cells was assessed by clonogenic assays following exposure to chemotherapeutic agents. The effect of NO mimetics on tumor chemosensitivity in vivo was determined using a mouse xenograft model of human prostate cancer. Drug efflux in vitro was assessed by measuring intracellular doxorubicin-associated fluorescence. RESULTS: Low concentrations of the NO mimetics glyceryl trinitrate (GTN) and isosorbide dinitrate attenuated hypoxia-induced resistance to doxorubicin and paclitaxel. Similar to hypoxia-induced drug resistance, inhibition of various components of the NO signaling pathway increased resistance to doxorubicin, whereas activation of the pathway with 8-bromo-cGMP attenuated hypoxia-induced resistance. Drug efflux was unaffected by hypoxia and inhibitors of drug efflux did not significantly attenuate hypoxia-induced chemoresistance. Compared with mice treated with doxorubicin alone, tumor growth was decreased in mice treated with doxorubicin and a transdermal GTN patch. The presence of GTN and GTN metabolites in plasma samples was confirmed by gas chromatography. CONCLUSION: Tumor hypoxia induces resistance to anticancer drugs by interfering with endogenous NO signaling and reactivation of NO signaling represents a novel approach to enhance chemotherapy. 相似文献
59.
Background
Despite extensive research, the five-year survival rate of oral squamous cell carcinoma (OSCC) patients has not improved. Effective treatment of OSCC requires the identification of molecular targets and signaling pathways to design appropriate therapeutic strategies. Several genes from the mTOR signaling pathway are known to be dysregulated in a wide spectrum of cancers. However, not much is known about the involvement of this pathway in tumorigenesis of OSCC. We therefore investigated the role of the tumor suppressor genes, TSC1 and TSC2, and other members of this pathway in tumorigenesis of OSCC. 相似文献60.
Effects of positive and negative pressure ventilation on cerebral blood volume of newborn infants 总被引:3,自引:0,他引:3
KS Palmer SA Spencer YABD Wickramasinghe T Wright DP Southall P Rolfe 《Acta paediatrica (Oslo, Norway : 1992)》1995,84(2):132-139
The effects of intermittent positive airway and continuous negative extrathoracic pressure ventilation on cerebral blood volume in preterm infants were studied using near infrared spectroscopy. In 12 infants continuous negative extrathoracic pressure caused a median decrease in cerebral blood volume of 0.14ml/100ml brain (95% confidence intervals (CI) 0.035–0.280) compared with no respiratory support. Oxygenated and deoxygenated haemoglobin also decreased, implying increased venous drainage as the main effect. In 17 infants intermittent positive pressure ventilation also caused a median reduction in cerebral blood volume of 0.06 ml/100 ml brain (95% CI 0.010–0.115) compared with endotracheal positive airway pressure. Deoxygenated haemoglobin increased by 0.07 ml/100 ml brain (95% CI 0.010–0.100) while oxygenated haemoglobin decreased by O.lOml/lOOml brain (95% CI 0.005–0.175). The increase in deoxygenated haemoglobin implies decreased venous drainage and the decrease in oxygenated haemoglobin implies that other factors may also be significant. Heart rate, blood pressure and oxygen saturation were monitored continuously and remained stable. 相似文献