全文获取类型
收费全文 | 620篇 |
免费 | 48篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 30篇 |
妇产科学 | 14篇 |
基础医学 | 74篇 |
口腔科学 | 5篇 |
临床医学 | 121篇 |
内科学 | 105篇 |
皮肤病学 | 13篇 |
神经病学 | 25篇 |
特种医学 | 64篇 |
外科学 | 48篇 |
综合类 | 5篇 |
预防医学 | 57篇 |
眼科学 | 6篇 |
药学 | 46篇 |
中国医学 | 2篇 |
肿瘤学 | 46篇 |
出版年
2023年 | 12篇 |
2022年 | 28篇 |
2021年 | 51篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 24篇 |
2017年 | 16篇 |
2016年 | 20篇 |
2015年 | 27篇 |
2014年 | 36篇 |
2013年 | 38篇 |
2012年 | 45篇 |
2011年 | 35篇 |
2010年 | 12篇 |
2009年 | 23篇 |
2008年 | 28篇 |
2007年 | 28篇 |
2006年 | 25篇 |
2005年 | 20篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 6篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有671条查询结果,搜索用时 15 毫秒
1.
2.
BACKGROUND: Chronic renal failure (CRF) is associated with an atherogenic
lipid profile and an increased risk of ischaemic cardiovascular disease.
The associated hyperlipidaemia is reportedly ameliorated by erythropoietin
(Epo) therapy. According to a recent report, rats studied 3 weeks after 5/6
nephrectomy and fed a high- protein diet exhibited increased activities of
hepatic HMG-CoA reductase (HMG-CoAR) and cholesterol 7 alpha-hydroxylase
(Ch-7 alpha- H), despite normal corresponding mRNA values. DESIGN AND
METHODS: This study was designed to examine the effects of naturally
progressing CRF of longer duration as well as those of Epo therapy on gene
expressions of the key factors involved in hepatic cholesterol metabolism,
i.e., LDL receptor (LDLR), HMG-CoAR, and Ch-7 alpha-H. Sprague-Dawley rats
were randomized to the CRF group (5/6 nephrectomy), Epo-treated CRF group
(given Epo 150 U/kg/twice weekly) and sham-operated, placebo- treated
normal controls. They were allowed free access to regular rat chow and
studied 6 weeks after surgery. Liver mRNAs and protein mass or activities
of the above factors were studied. RESULTS: Plasma cholesterol
concentration was significantly increased in the CRF group (P < 0.001)
and was modestly lowered (P < 0.05) by Epo therapy. However, microsomal
cholesterol concentration and LDLR, HMG-CoAR, and Ch-7 alpha-H mRNA as well
as HMG-CoAR activity, and Ch-7 alpha-H and LDLR protein mass measurements
were virtually identical in the three groups. Thus, hepatic LDLR, HMG-CoAR,
and Ch-7 alpha-H mRNA and protein measurements in rats with CRF were
similar to those of the normal control group representing an inappropriate
response to the associated hypercholesterolemia. Epo therapy led to partial
amelioration of CRF- associated hypercholesterolaemia with no discernible
effect on hepatic tissue expression of the above factors.
相似文献
3.
4.
Raymond E. Sicard PhD ; Linh M. P. Nguyen BS ; Jonathan D. Witzke BA 《Wound repair and regeneration》1997,5(1):39-46
Repair and regeneration are mutually exclusive responses to injury. Previous studies have shown that wound fluids promote proliferation, but not differentiation, of myoblasts in vitro. This study explored the ability of the repair environment within polyvinyl alcohol sponges to support cellular events of skeletal muscle regeneration in vivo. Neonatal rat L8 myoblasts were modified to express beta-galactosidase then inoculated into plain sponges or sponges containing minced muscle. Labeled myoblasts were found in myotubes within minced muscle. In contrast, myoblasts inoculated into sponges lacking muscle remained mononucleate. Occurrence of labeled myoblasts within myotubes, which required fusion, represents differentiation of inoculated myoblasts to participate in regeneration. Failure of myoblasts to form myotubes in sponges lacking muscle suggests that this wound repair environment cannot support morphologic differentiation of myoblasts. Although this repair environment can support the survival of myoblasts, it did not support myogenesis, an event necessary to complete skeletal muscle regeneration. Data from this study reinforce earlier studies in vitro and suggest that the properties attributed to wound fluids are inherent in the wound environment. Whether the inability of this environment to support myogenesis is the consequence of the absence of essential factors or the presence of inhibitors remains to be determined. 相似文献
5.
6.
Linh Luong James Lachaud Fiona G. Kouyoumdjian Stephen W. Hwang Cilia Mejia-Lancheros 《Canadian journal of public health. Revue canadienne de santé publique》2021,112(2):270
ObjectiveTo examine the effect of a Housing First (HF) intervention and health-related risk factors on incarceration among adults with experiences of homelessness and mental illness.MethodsParticipants (N = 508) were recruited at the Toronto site of the At Home/Chez Soi study. The outcome was incarceration in Ontario from 2009 to 2014. Exposures were intervention group (HF vs. treatment as usual), Axis I mental health diagnoses, emergency department (ED) visit, and history of traumatic brain injury (TBI). Logistic regression was used to examine the association between exposures and incarceration.ResultsOf 508 participants, 220 (43.3%) were incarcerated at least once during the study period. Among those incarcerated, 81.9% were male, 52.7% had been diagnosed with alcohol dependence/abuse, 60.9% had been diagnosed with substance dependence/abuse, 65.1% reported having visited an ED within the last 6 months, and 66.4% had a history of TBI. After adjusting for demographic covariates, substance dependence/abuse (aOR: 2.06; 95% CI: 1.40, 3.03), alcohol dependence/abuse (aOR: 1.52, 95% CI: 1.04, 2.22), ED visit (aOR: 1.54; 95% CI: 1.02, 2.32), and history of TBI (aOR: 2.60; 95% CI: 1.75, 3.85) were associated with incarceration. We found no significant effect of the HF intervention on incarceration outcome (aOR: 1.08; 95% CI: 0.76, 1.55).ConclusionsAmong adults with experiences of homelessness and severe mental illness, those with substance and alcohol dependence/abuse disorders, history of TBI, and recent ED visits were at increased odds of incarceration. Strategies are needed to prevent and reduce incarceration for this population, including treatment of mental illness in the community.Supplementary InformationThe online version of this article (10.17269/s41997-020-00433-z) contains supplementary material, which is available to authorized users. 相似文献
7.
Rene E Sotomayor Melissa Washington Linh Nguyen Rahma Nyang'anyi Dennis M Hinton Ming Chou 《Toxicological sciences》2003,73(2):329-338
We studied the effects of intermittent exposure to aflatoxin B1 (AFB1) on hepatic DNA and RNA adduct formation. Fisher-344 male rats were fed 0.01, 0.04, 0.4, or 1.6 ppm of AFB1 intermittently for 8, 12, 16, and 20 weeks, alternating with 4 weeks of dosing and 4 weeks of rest. Other groups of rats were fed 1.6 ppm of AFB1 continuously for 4, 8, 12, and 16 weeks. Control rats received AFB1-free NIH-31 meal diet. AFB1-DNA and -RNA adducts were measured by HPLC with fluorescence detection. The data are presented as total DNA or RNA adducts. The DNA and RNA adduct levels increased or decreased depending on the cycles of dosing and rest. Rats removed from treatment 1 month after 1 or 2 dosing cycles (8 and 16 weeks of intermittent exposure) showed approximately a twofold decrease in DNA adduct levels and a two- to elevenfold decrease in RNA adduct levels compared with rats euthanized immediately after the last dosing cycle (12 and 20 weeks of intermittent exposure). Our data indicate that DNA and RNA adducts increased linearly, from 0.01 ppm to 1.6 ppm of AFB1 after 12 and 20 weeks of intermittent treatment. A linear dose response was also apparent for DNA but not for RNA adducts after 8 and 16 weeks of treatment. As biomarkers of exposure, AFB1-RNA adducts were three to nine times more sensitive than AFB1-DNA adducts but showed greater variability. These results suggest that binding of AFB1 to hepatic DNA is a linear function of the dose, regardless of the way this is administered. The dose-response relationship for RNA adducts depends on the length of the no-dosing cycles and on the turnover rate of RNA. 相似文献
8.
Abstract: Haemoptysis in otherwise healthy children is an uncommon event. Two cases of massive haemoptysis, subsequently requiring lobectomy, are discussed. In each case, foreign vegetable matter was identified despite previously normal bronchoscopy and minimal changes on chest radiograph. 相似文献
9.
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
10.