全文获取类型
收费全文 | 524篇 |
免费 | 40篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 29篇 |
妇产科学 | 13篇 |
基础医学 | 52篇 |
口腔科学 | 13篇 |
临床医学 | 54篇 |
内科学 | 154篇 |
皮肤病学 | 6篇 |
神经病学 | 33篇 |
特种医学 | 47篇 |
外科学 | 39篇 |
综合类 | 41篇 |
预防医学 | 20篇 |
眼科学 | 6篇 |
药学 | 34篇 |
肿瘤学 | 48篇 |
出版年
2022年 | 7篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 18篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 23篇 |
2009年 | 19篇 |
2008年 | 23篇 |
2007年 | 32篇 |
2006年 | 27篇 |
2005年 | 17篇 |
2004年 | 22篇 |
2003年 | 17篇 |
2002年 | 8篇 |
2001年 | 21篇 |
2000年 | 7篇 |
1999年 | 13篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 21篇 |
1995年 | 12篇 |
1994年 | 23篇 |
1993年 | 15篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 22篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有591条查询结果,搜索用时 15 毫秒
11.
Coexpression of the genes for platelet-derived growth factor and its receptor in human T-cell lines infected with HTLV-I 总被引:2,自引:0,他引:2
A S Goustin T Galanopoulos V S Kalyanaraman P Pantazis 《Growth factors (Chur, Switzerland)》1990,2(2-3):189-195
Several HTLV-I-infected T-cell lines express the two genes encoding platelet-derived growth factor (PDGF). Therefore, we examined the question of a possible self-stimulatory mechanism of proliferation involving PDGF in these cells. Using a nucleic acid probe and an antibody specific for the PDGF-B receptor (PDGFR-B), we examined four established human T-cell lines infected with HTLV-I, as well as several noninfected T-cell lines for expression of the PDGF-B receptor. Previous reports indicate that lymphocytes do not display receptors for PDGF; our results show that two noninfected T-cell lines (HUT-78, CCRF-HSB-2) expressed the canonical 5.5-kb PDGFR mRNA, and two HTLV-I-infected T-cell lines (C10/MJ, MT-2) expressed a novel PDGFR mRNA of 4.8 kb. Concomitantly, the cell lines expressing PDGFR mRNA also synthesize PDGFR proteins immunoprecipitated by the antibody to PDGFR-B. Differences were observed in the molecular weight of PDGFR molecules immunoprecipitated from uninfected and HTLV-infected T-cells. Immunofluorescence studies demonstrated that the PDGFR-B proteins are localized primarily on the cell external membrane. The results suggest that the HTLV-I-infected T-cells acquire an autostimulatory mechanism of cell proliferation that involves PDGF. 相似文献
12.
Arif JM; Gairola CG; Glauert HP; Kelloff GJ; Lubet RA; Gupta RC 《Carcinogenesis》1998,19(8):1515-1517
The present study investigated the effects of dietary oltipraz on cigarette
smoke-related lipophilic DNA adduct formation. Female Sprague- Dawley rats
were exposed daily to sidestream cigarette smoke in a whole- body exposure
chamber 6 h/day for 4 consecutive weeks. One group of rats was maintained
on control diet while another group received the same diet supplemented
with either a low (167 p.p.m.) or high (500 p.p.m.) dose of oltipraz,
starting 1 week prior to initiation of smoke exposure until the end of the
experiment. Analysis of lipophilic DNA adducts by the nuclease P1-mediated
32P-post-labeling showed up to five smoke-related adducts. Adduct no. 5
predominated in both the lung and the heart while adduct nos 3 and 2
predominated in the trachea and bladder, respectively. Quantitative
analysis revealed that the total adduct level was the highest in lungs
(270+/-68 adducts/10(10) nucleotides), followed by trachea (196+/-48
adducts/10(10) nucleotides), heart (141+/-22 adducts/10(10) nucleotides)
and bladder (85+/-16 adducts/10(10) nucleotides). High dose oltipraz
treatment reduced the adduct levels in lungs and bladder by >60%, while
the reduction in lungs in the low-dose group was approximately 35%. In
trachea, the effect of low and high dietary oltipraz on smoke DNA adduction
was equivocal, while smoke-related DNA adducts in the heart were minimally
inhibited by high-dose oltipraz. In a repeat experiment that employed a
3-fold lower dose of cigarette smoke, oltipraz (500 p.p.m.) was found to
inhibit the formation of DNA adducts in rat lungs and trachea by 80 and
65%, respectively. These data clearly demonstrate a high efficacy of
oltipraz in inhibiting the formation of cigarette smoke-induced DNA adducts
in the target tissues.
相似文献
13.
Mutation of the p53 tumor suppressor gene in spontaneously occurring osteosarcomas of the dog 总被引:8,自引:0,他引:8
Inactivation of the p53 tumor suppressor gene has been implicated in the
pathogenesis of numerous human cancers, including osteosarcomas.
Appendicular osteosarcomas of the dog appear to be a good model for their
human equivalent with regard to biologic behavior, epidemiology and
histopathology. We individually screened exons 5-8 of the p53 gene for
mutations in 15 canine appendicular osteosarcomas using 'Cold' SSCP to
compare the role of this gene in human and canine osteosarcoma
tumorigenesis. Seven of the tumors (47%) exhibited point mutations, with
one tumor possessing two mutations within different exons. Of these, seven
were missense mutations and the eighth was a 'silent' mutation potentially
affecting the exon 6-7 splicing region. Five of the missense mutations were
located in highly conserved regions IV and V, while another corresponded
with the highly conserved codon 220 mutational hotspot located outside the
conserved domains. The locations and types of mutations were nearly
identical to those reported in human cancer. These findings provide strong
evidence of the involvement of p53 mutations in the development of canine
appendicular osteosarcomas. Canine osteosarcomas appear to be a promising
model for their human equivalent on a clinical, pathologic, and molecular
level.
相似文献
14.
本文对模式产地的山药Piper haneei Maxim, var, hancei Maxim,和腺鳞蒟P. kancei Maxim var. squamiglanduferum Fan var. nov.进行了原植物形态特征和花序轴、花序梗、茎、叶的显微特征以及化学成分的TLC及UV比较。挥发油的GC—MS研究共鉴定出38个成分,其中28个是胡椒属植物中首次报道的成分。结果证明了在福建长期以来被认为是山药的腺鳞蒟与模式产地的山药有较大差别,尤其是腺鳞蒟叶上表面有腺鳞,是迄今为止第1个发现具有腺鳞的胡椒属植物。据此把腺鳞蒟作为新变种从山药中分出。腺鳞药是福建南部海风藤主要来源之一。 相似文献
15.
16.
Knowledge,attitude and practice among Health Visitors in the United Kingdom toward children's oral health
下载免费PDF全文
![点击此处可从《Public health nursing (Boston, Mass.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
17.
Pawan Sinha Margaret M. Kjelgaard Tapan K. Gandhi Kleovoulos Tsourides Annie L. Cardinaux Dimitrios Pantazis Sidney P. Diamond Richard M. Held 《Proceedings of the National Academy of Sciences of the United States of America》2014,111(42):15220-15225
A rich collection of empirical findings accumulated over the past three decades attests to the diversity of traits that constitute the autism phenotypes. It is unclear whether subsets of these traits share any underlying causality. This lack of a cohesive conceptualization of the disorder has complicated the search for broadly effective therapies, diagnostic markers, and neural/genetic correlates. In this paper, we describe how theoretical considerations and a review of empirical data lead to the hypothesis that some salient aspects of the autism phenotype may be manifestations of an underlying impairment in predictive abilities. With compromised prediction skills, an individual with autism inhabits a seemingly “magical” world wherein events occur unexpectedly and without cause. Immersion in such a capricious environment can prove overwhelming and compromise one’s ability to effectively interact with it. If validated, this hypothesis has the potential of providing unifying insights into multiple aspects of autism, with attendant benefits for improving diagnosis and therapy. 相似文献
18.
19.
20.
Styles LA; Schalkwijk CG; Aarsman AJ; Vichinsky EP; Lubin BH; Kuypers FA 《Blood》1996,87(6):2573-2578
Acute chest syndrome (ACS) is associated with significant morbidity and is the leading cause of death in patients with sickle cell disease (SCD). Recent reports suggest that bone marrow fat embolism can be detected in many cases of severe ACS. Secretory phospholipase A2 (sPLA2) is an important inflammatory mediator and liberates free fatty acids, which are felt to be responsible for the acute lung injury of the fat embolism syndrome. We measured SPLA2 levels in 35 SCD patients during 20 admissions for ACS, 10 admissions for vaso-occlusive crisis, and during 12 clinic visits when patients were at the steady state. Eleven non-SCD patients with pneumonia were also evaluated. To determine if there was a relationship between sPLA2 and the severity of ACS we correlated SPLA2 levels with the clinical course of the patient. In comparison with normal controls (mean = 3.1 +/- 1.1 ng/mL), the non- SCD patients with pneumonia (mean = 68.6 +/- 82.9 ng/mL) and all three SCD patient groups had an elevation of SPLA2 (steady state mean = 10.0 +/- 8.4 ng/mL; vaso-occlusive crisis mean = 23.7 +/- 40.5 ng/mL; ACS mean = 336 +/- 209 ng/mL). In patients with ACS sPLA2 levels were 100- fold greater than normal control values, 35 times greater than values in SCD patients at baseline, and five times greater than non-SCD patients with pneumonia. The degree of SPLA2 elevation in ACS correlated with three different measures of clinical severity and, in patients followed sequentially, the rise in SPLA2 coincided with the onset of ACS. The dramatic elevation of SPLA2 in patients with ACS but not in patients with vaso-occlusive crisis or non-SCD patients with pneumonia and the correlation between levels of SPLA2 and clinical severity suggest a role for SPLA2 in the diagnosis and, perhaps, in the pathophysiology of patients with ACS. 相似文献