全文获取类型
收费全文 | 1452篇 |
免费 | 128篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 29篇 |
妇产科学 | 51篇 |
基础医学 | 163篇 |
口腔科学 | 41篇 |
临床医学 | 164篇 |
内科学 | 371篇 |
皮肤病学 | 25篇 |
神经病学 | 70篇 |
特种医学 | 119篇 |
外科学 | 156篇 |
综合类 | 35篇 |
一般理论 | 1篇 |
预防医学 | 172篇 |
眼科学 | 51篇 |
药学 | 85篇 |
中国医学 | 2篇 |
肿瘤学 | 53篇 |
出版年
2022年 | 12篇 |
2021年 | 14篇 |
2020年 | 14篇 |
2019年 | 19篇 |
2018年 | 19篇 |
2017年 | 16篇 |
2016年 | 14篇 |
2015年 | 21篇 |
2014年 | 38篇 |
2013年 | 55篇 |
2012年 | 69篇 |
2011年 | 52篇 |
2010年 | 41篇 |
2009年 | 52篇 |
2008年 | 32篇 |
2007年 | 81篇 |
2006年 | 63篇 |
2005年 | 56篇 |
2004年 | 49篇 |
2003年 | 47篇 |
2002年 | 45篇 |
2001年 | 28篇 |
2000年 | 35篇 |
1999年 | 29篇 |
1998年 | 36篇 |
1997年 | 27篇 |
1996年 | 22篇 |
1995年 | 26篇 |
1994年 | 20篇 |
1993年 | 19篇 |
1992年 | 19篇 |
1991年 | 24篇 |
1990年 | 25篇 |
1989年 | 33篇 |
1988年 | 29篇 |
1987年 | 33篇 |
1986年 | 27篇 |
1985年 | 34篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1981年 | 18篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1975年 | 28篇 |
1974年 | 15篇 |
1973年 | 21篇 |
1969年 | 17篇 |
排序方式: 共有1599条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Repeated exposure to sham testing procedures reduces reflex withdrawal and hot-plate latencies: attenuation of tonic descending inhibition? 总被引:1,自引:0,他引:1
Five days' repeated exposure of experimentally naive rats to the experimental environment and to sham nociceptive testing procedures ('habituation') reduced the latency for reflex withdrawal of the hindpaw from hot water (49 degrees C) by 43%, to that of spinalised habituated or novice animals. Hot-plate (50 degrees C) paw lick latencies were reduced equally (40%) by habituation or parachlorophenylalanine, and were increased 32% by D,L-5-hydroxytryptophan. Neither drug affected hot-plate latencies of habituated animals. Naloxone had no effect on flexor withdrawal or hot-plate latencies in either novice or habituated animals. These results suggest that habituation substantially attenuates tonic serotonergic inhibition of spinal nociceptive transmission. 相似文献
5.
Dorit Naot Usha Bava Brya Matthews Karen E Callon Gregory D Gamble Michael Black Sarah Song Rocco P Pitto Tim Cundy Jill Cornish Ian R Reid 《Journal of bone and mineral research》2007,22(2):298-309
Paget's disease is a focal condition of bone. To study changes in cells within pagetic lesions, we cultured osteoblasts and stromal cells from 22 patients and compared gene expression in these cells to cells from healthy bone. We identified several differentially regulated genes, and we suggest that these changes could lead to the formation of the lesions. INTRODUCTION: Paget's disease is a focal condition of bone of unknown cause. Although it is regarded as primarily an osteoclast disorder, the tight coupling of the activity of osteoclasts and osteoblasts suggests that the osteoblast could play a key role in its pathogenesis. The aim of the study was to identify possible changes in pagetic osteoblasts and stromal cells that might contribute to the development of pagetic lesions. MATERIALS AND METHODS: Candidate genes were identified based on known bone cell regulators, supplemented with microarray analysis. Gene expression was determined by real-time PCR in primary cultures of osteoblasts and bone marrow stromal cells from pagetic patients and control subjects. Concentrations of secreted proteins were determined by ELISA. RESULTS: Dickkopf1 mRNA and protein levels were increased in both pagetic osteoblast and stromal cell cultures, and interleukin (IL)-1 and IL-6 were overexpressed in pagetic osteoblasts. These changes parallel recent findings in myeloma bone disease, which shares some clinical similarities with Paget's disease. Alkaline phosphatase was overexpressed, and bone sialoprotein and osteocalcin were underexpressed in pagetic osteoblasts, consistent with their circulating levels in pagetic patients. It is hypothesized that overexpression of Dickkopf1, IL-1, and IL-6 would result in stimulation of osteoclast proliferation and inhibition of osteoblast growth, leading to the development of the characteristic lytic bone lesions. By stimulating osteoblast differentiation, Dickkopf1 and IL-6 may also promote mineralization, leading to the conversion of lytic lesions to sclerotic. CONCLUSIONS: These findings suggest that dysregulated gene expression in pagetic osteoblasts could cause the changes in bone cell number and function characteristic of Paget's disease. 相似文献
6.
7.
8.
Cytotoxic T lymphocytes (CTL) induce in target cells a rapid, prelytic fragmentation of target cell DNA, accompanied by apoptosis. In contrast, complement and (with a few exceptions) chemical and physical means of inducing cytolysis induce necrosis, without DNA fragmentation. The function of the unusual DNA fragmentation induced by CTL remains to be elucidated. The major recognized function of CTL is in halting virus infections. Earlier, we proposed that CTL might halt virus infections prelytically, by fragmenting viral and cellular nucleic acids, and that in this case, cytolysis per se might be a less important function of CTL. We report here experiments designed to detect prelytic halt of virus replication. We employed in vivo-like conditions: fibroblast targets (difficult to lyse) were infected with herpes simplex virus (HSV), then incubated at low E/T cell ratios overnight. At the highest E/T ratios which produced less than 10% CTL-induced lysis, plaque-forming unit yield was reduced by about 50%. At higher E/T ratios which lysed 1/6 to 1/3 of the infected target cells, 3/4 to 9/10 of the virus production was prevented. The discrepancy between the level of lysis and the reduction in virus yield is evidence for significant CTL-induced prelytic halt of HSV replication. At present, it is unclear whether the antiviral effect observed involves an activity of CTL distinct from their lytic ability, such as their DNA fragmenting ability. 相似文献
9.
J M Morse G Ewing D Gamble P Donahue 《Canadian journal of public health. Revue canadienne de santé publique》1992,83(3):213-216
To examine the effect of increased and decreased fluids on breast milk supply, a pilot study using a cross-over design with 10 mother-infant pairs was completed. Baseline measures of milk supply were determined over a 3-day period of normal fluid intake based on body weight. Subjects were studied over 3-day periods when fluid intake was alternately 50% more and 50% less than normal level. Milk supply was calculated by averaging breast milk intake, determined by test weighing the infants with electronic scales, and milk yield, measured either by total breast expression with an electric breast pump or a combination of expression and test weighing. Although milk supply decreased with decreased fluids and increased with increased fluids, this change was not statistically significant. Recommendations for further research include replication using subjects' usual fluid intake as a baseline and replication using mothers suspected of insufficient milk syndrome. 相似文献
10.
In vitro characterization of peptide-modified p(AAm-co-EG/AAc) IPN-coated titanium implants. 总被引:1,自引:0,他引:1
Thomas A Barber Lara J Gamble David G Castner Kevin E Healy 《Journal of orthopaedic research》2006,24(7):1366-1376
Interpenetrating polymer networks (IPNs) of poly(acrylamide-co-ethylene glycol/acrylic acid) [p(AAm-co-EG/AAc)] functionalized with an -Arg-Gly-Asp- containing peptide derived from rat bone sialoprotein [bsp-RGD(15)] were grafted to titanium implants in an effort to modulate osteoblast behavior in vitro. Surface characterization data were consistent with the presence of an IPN, and ligand density measurements established that the range of peptide density on the modified implants spanned three orders of magnitude (0.01-20 pmol/cm2). In vitro biological characterization of the modified implants employing the primary rat calvarial osteoblast (RCO) model resulted in the identification of a critical ligand density (0.01相似文献