全文获取类型
收费全文 | 2189篇 |
免费 | 187篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 35篇 |
儿科学 | 88篇 |
妇产科学 | 55篇 |
基础医学 | 252篇 |
口腔科学 | 26篇 |
临床医学 | 237篇 |
内科学 | 507篇 |
皮肤病学 | 16篇 |
神经病学 | 111篇 |
特种医学 | 163篇 |
外科学 | 245篇 |
综合类 | 143篇 |
一般理论 | 1篇 |
预防医学 | 246篇 |
眼科学 | 38篇 |
药学 | 99篇 |
中国医学 | 1篇 |
肿瘤学 | 117篇 |
出版年
2023年 | 19篇 |
2022年 | 27篇 |
2021年 | 54篇 |
2020年 | 39篇 |
2019年 | 50篇 |
2018年 | 72篇 |
2017年 | 42篇 |
2016年 | 48篇 |
2015年 | 47篇 |
2014年 | 49篇 |
2013年 | 108篇 |
2012年 | 89篇 |
2011年 | 98篇 |
2010年 | 66篇 |
2009年 | 72篇 |
2008年 | 85篇 |
2007年 | 110篇 |
2006年 | 87篇 |
2005年 | 81篇 |
2004年 | 67篇 |
2003年 | 53篇 |
2002年 | 37篇 |
2001年 | 63篇 |
2000年 | 74篇 |
1999年 | 58篇 |
1998年 | 34篇 |
1997年 | 31篇 |
1996年 | 25篇 |
1995年 | 15篇 |
1994年 | 26篇 |
1993年 | 20篇 |
1992年 | 46篇 |
1991年 | 35篇 |
1990年 | 31篇 |
1989年 | 23篇 |
1988年 | 39篇 |
1987年 | 51篇 |
1986年 | 26篇 |
1985年 | 18篇 |
1984年 | 24篇 |
1983年 | 20篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 17篇 |
1979年 | 17篇 |
1977年 | 16篇 |
1973年 | 21篇 |
1969年 | 17篇 |
1968年 | 16篇 |
1967年 | 17篇 |
排序方式: 共有2380条查询结果,搜索用时 15 毫秒
41.
Non-invasive detection of fecal protein kinase C betaII and zeta messenger RNA: putative biomarkers for colon cancer 总被引:2,自引:0,他引:2
Davidson LA; Aymond CM; Jiang YH; Turner ND; Lupton JR; Chapkin RS 《Carcinogenesis》1998,19(2):253-257
We have developed a non-invasive method utilizing feces, containing
sloughed colonocytes, as a sensitive technique for detecting diagnostic
colonic biomarkers. In this study, we used the rat colon carcinogenesis
model to determine if changes in fecal protein kinase C (PKC) expression
have predictive value in monitoring the neoplastic process. Weanling rats
were injected with saline or azoxymethane (AOM) and 36 weeks later fecal
samples and mucosa were collected, poly A+ RNA isolated, and quantitative
RT-PCR performed using primers to PKC betaII and zeta. Fecal PKC betaII and
zeta mRNA levels were altered by the presence of a tumor, with
tumor-bearing animals having a 3-fold higher (P < 0.05) PKC betaII
expression as compared with animals without tumors. In addition,
AOM-injection increased mucosal PKC betaII mRNA expression compared with
saline controls. No effect of tumor incidence on mucosal PKC betaII
expression was observed. In contrast, fecal PKC zeta expression was
2.5-fold lower (P < 0.05) in animals injected with azoxymethane versus
saline. Since tumor incidence exerts a reciprocal effect on fecal PKC
betaII and zeta mRNA expression, data were also expressed as the ratio
between PKC betaII and zeta. The isozyme ratio was strongly related to
tumor incidence, i.e. ratio for animals with tumors was 2.18 +/- 1.25,
animals without tumors was 0.50 +/- 0.16, P = 0.025. We demonstrate that
the expression of fecal PKC betaII and zeta may serve as a noninvasive
marker for development of colon tumors. A sensitive technique for the
detection of colon cancer is of importance since early diagnosis can
substantially reduce mortality.
相似文献
42.
43.
Collison M Glazier AM Graham D Morton JJ Dominiczak MH Aitman TJ Connell JM Gould GW Dominiczak AF 《Diabetes》2000,49(12):2222-2226
Insulin resistance is of pathogenic importance in several common human disorders including type 2 diabetes, hypertension, obesity and hyperlipidemia, but the underlying mechanisms are unknown. The spontaneously hypertensive rat (SHR) is a model of these human insulin resistance syndromes. Quantitative trait loci (QTLs) for SHR defects in glucose and fatty acid metabolism, hypertriglyceridemia, and hypertension map to a single region on rat chromosome 4. Genetic analysis of an SHR derived from a National Institutes of Health colony led to the identification of a causative mutation in the SHR Cd36. We have investigated glucose and fatty acid metabolism in the stroke-prone SHR (SHRSP). We demonstrate defects in insulin action on 2-deoxy-D-glucose transport (SHRSP 3.3 +/- 1.5 vs. 21.0 +/- 7.4 pmol x min(-1) x [20 microl packed cells](-1), SHRSP vs. WKY, respectively, P = 0.01) and inhibition of catecholamine-stimulated lipolysis (P < 0.05 at all concentrations of insulin) in adipocytes isolated from SHRSP. In contrast, basal levels of catecholamine-stimulated nonesterified free fatty acid (NEFA) release and plasma levels of NEFA are similar in SHRSP and WKY. These results are in agreement with the data on the SHR.4 congenic strain, which suggested that the QTL containing Cd36 mutations accounted for the entire defect in basal catecholamine action but only for approximately 40% of the SHR defect in insulin action. In the SHR, both abnormalities appear consequent of defective Cd36 expression. Because Cd36 sequence and expression are apparently normal in SHRSP, it is likely that the molecular mechanism for defective insulin action in this strain is caused by a gene(s) different than Cd36. 相似文献
44.
Kevin P. Fennelly Amy L. Davidow Shelly L. Miller Nancy Connell Jerrold J. Ellner 《Emerging infectious diseases》2004,10(6):996-1001
The lack of identified exposures in 2 of the 11 cases of bioterrorism-related inhalation anthrax in 2001 raised uncertainty about the infectious dose and transmission of Bacillus anthracis. We used the Wells-Riley mathematical model of airborne infection to estimate 1) the exposure concentrations in postal facilities where cases of inhalation anthrax occurred and 2) the risk for infection in various hypothetical scenarios of exposure to B. anthracis aerosolized from contaminated mail in residential settings. These models suggest that a small number of cases of inhalation anthrax can be expected when large numbers of persons are exposed to low concentrations of B. anthracis. The risk for inhalation anthrax is determined not only by bacillary virulence factors but also by infectious aerosol production and removal rates and by host factors. 相似文献
45.
BackgroundSmall bowel involvement of Clostridium difficile is increasingly encountered. Data on many management aspects are lacking.AimTo synthesis existing reports and assess the frequency, pathophysiology, outcomes, risk factors, diagnosis and management of C. difficle enteritis.MethodsA systematic review of the literature was conducted to evaluate evidence regarding frequency, pathophysiology, risk factors, optimal diagnosis, management and outcomes for C. difficle enteritis. Three major databases (PubMed, MEDLINE and the Cochrane Library) were searched. The review included original articles reporting C. difficle enteritis from January 1950 to December 2012.ResultsC. difficle enteritis is rare but increasingly encountered. Presentation is variable and distinct predisposing factors include emergency surgery, white race and increased age. Diagnosis generally involves a sensitive but often non specific screening test for C. difficile antigens. Oral metronidazole represents first line therapy and surgery may be required for complications. Outcomes are inconsistent but may be improving.ConclusionsA high index of clinical suspicion, early diagnosis and treatment are vital. Further prospective studies are needed to determine the significance of asymptomatic small bowel C. difficile infections. 相似文献
46.
47.
48.
49.
50.