全文获取类型
收费全文 | 2341篇 |
免费 | 143篇 |
国内免费 | 80篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 108篇 |
妇产科学 | 65篇 |
基础医学 | 217篇 |
口腔科学 | 58篇 |
临床医学 | 256篇 |
内科学 | 415篇 |
皮肤病学 | 28篇 |
神经病学 | 164篇 |
特种医学 | 378篇 |
外科学 | 250篇 |
综合类 | 57篇 |
预防医学 | 226篇 |
眼科学 | 16篇 |
药学 | 148篇 |
中国医学 | 2篇 |
肿瘤学 | 153篇 |
出版年
2021年 | 24篇 |
2019年 | 18篇 |
2018年 | 26篇 |
2017年 | 21篇 |
2016年 | 32篇 |
2015年 | 30篇 |
2014年 | 36篇 |
2013年 | 55篇 |
2012年 | 86篇 |
2011年 | 74篇 |
2010年 | 58篇 |
2009年 | 58篇 |
2008年 | 65篇 |
2007年 | 118篇 |
2006年 | 65篇 |
2005年 | 77篇 |
2004年 | 62篇 |
2003年 | 64篇 |
2002年 | 54篇 |
2001年 | 52篇 |
2000年 | 56篇 |
1999年 | 65篇 |
1998年 | 77篇 |
1997年 | 84篇 |
1996年 | 66篇 |
1995年 | 81篇 |
1994年 | 49篇 |
1993年 | 50篇 |
1992年 | 55篇 |
1991年 | 57篇 |
1990年 | 42篇 |
1989年 | 74篇 |
1988年 | 67篇 |
1987年 | 62篇 |
1986年 | 52篇 |
1985年 | 66篇 |
1984年 | 37篇 |
1983年 | 30篇 |
1982年 | 35篇 |
1981年 | 20篇 |
1980年 | 32篇 |
1979年 | 23篇 |
1978年 | 19篇 |
1977年 | 26篇 |
1976年 | 30篇 |
1975年 | 22篇 |
1974年 | 23篇 |
1971年 | 27篇 |
1970年 | 21篇 |
1969年 | 18篇 |
排序方式: 共有2564条查询结果,搜索用时 156 毫秒
21.
This paper examines ethical criteria for the shaping of an emergingtechnology applied internationally in environmental regulation:quantitative risk assessment-risk management. The role of thephysician in its application, especially in the genetic testingthat will be employed, underlines the importance of understandingthe nature and prospects for reshaping of this technology toenable ethical practice. The Cartesian or mechanistic model(which currently dominates the technology) excludes factorsof emotion, making the connection between assessment and managementunfruitful functionally and ethically, and makes the model unresponsiveto human needs. The emotional factors, nested and mediated inthe organic hierarchy of the ecologically-defined community,constitute key psychological, social, cultural and politicalelements of the total burden of risk. Ethical criteria consistentwith an open society are suggested for reshaping the model toenable effective management. 相似文献
22.
23.
Abstract In this study, gingival crevicular fluid (GCF) was collected from around a canine tooth, in children, before and during orthodontic tooth movement. The aim was to identify and quantify the glycosaminoglycan (GAG) components of GCF and relate them to tooth movement, gingival inflammation, plaque accumulation, pocket probing depth and GCF volume recorded at the site of sampling. GAG in GCF samples, collected for a 15-min period into microcapillary tubes, were separated electrophoretically, stained with Alcian blue and quantified using a laser densitometer. 2 GAG components of hyaluronic acid (HA) and chondroitin sulphate (CS) were identified. The increase in GCF volume during orthodontic tooth movement was only partly due to increased gingival inflammation, GAG levels varied with different types of orthodontic tooth movement. In GCF, levels of CS, in particular, may reflect the changes in the deeper periodontal tissues which could be monitored during orthodontic tooth movements. 相似文献
24.
Samuels L Entwistle J Holmes E Eaton D Thomas MP Menzano G Promisloff R 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2004,50(3):234-236
The traditional extracorporeal membrane oxygenation circuit uses a centrifugal pump. These pumps require close monitoring and are subject to complications. In addition, they do not take advantage of the potential benefits of pulsatile flow. These extracorporeal membrane oxygenation circuits use a single pump with an inline oxygenator. If cardiac failure persists after respiratory recovery has occurred, removal of the oxygenator requires an additional procedure to convert the patient to biventricular support. This report describes a circuit in which an oxygenator is connected to a pulsatile ventricular assist device. Single and dual circuit configurations are illustrated. Recommendations for pulmonary care during support are also described. 相似文献
25.
Application of reflectance spectroscopy to the estimation of uric acid, urea and glucose: an evaluation of the Ames Seralyzer
下载免费PDF全文
![点击此处可从《Journal of clinical pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An original approach to the measurement of analytes in clinical chemistry has now become available, in which dry reagent strip technology is linked to measurement by reflectance spectroscopy. The present studies have evaluated the performance of the first of these test systems—for uric acid, urea and glucose, in serum—by comparison with conventional liquid chemistry methods. Satisfactory performance in terms of both precision and accuracy was obtained for all three test systems, the current “state-of-the-art” performance criteria being met; the Seralyzer system proved reliable and easy to use in the hands of trained operators. It should find a place as a “Stat” analyser in the laboratory, in specified wards and in Health Centres. 相似文献
26.
27.
Influence of co-culture with established human endometrial epithelial and stromal cell lines on sperm movement characteristics 总被引:2,自引:0,他引:2
The effects of co-culture of human spermatozoa with human immortalized
endometrial cells - epithelial or stromal - on sperm movement
characteristics, including hyperactivation, were studied using computer-
assisted sperm analysis (CASA). Epithelial and stromal cell types could be
separated following 8-10 days of culture of endometrial cells originating
from human biopsies. Both cell types were immortalized by the SV 40 large T
antigen. Co-incubation of sperm with epithelial and stromal monolayers
enhanced the rate of hyperactivation: 24.9% (P <0.05) and 17.8% (P =
0.05) versus 9.5% as control, respectively, whereas the majority of
motility parameters remained unchanged. Conditioned media had no effect
upon sperm parameters, including hyperactivation. Co-incubation with either
monolayer was able to maintain sperm motility over a longer period than
incubation in control medium alone. In four patients whose spermatozoa did
not exhibit hyperactivation, co-incubation with epithelial cells, but not
conditioned medium, allowed normal rates of hyperactivation (range: 6.9-
15.6%).
相似文献
28.
29.
Samuels ME Forbey KC Reid JE Abkevich V Bulka K Wardell BR Bowen BR Hopkins PN Hunt SC Ballinger DG Skolnick MH Wagner S 《Clinical genetics》2001,59(2):88-98
Defects in the lipoprotein lipase (LPL) gene are associated with dyslipidemia in the general population. Several rare mutations in the gene, as well as two common coding region polymorphisms, D9N and N291S, exhibit deleterious effects on circulating lipid levels. Using a linkage-based approach, we have identified a large Utah kindred segregating the D9N variant in the LPL gene. The kindred was ascertained for premature coronary heart disease and was expanded based on familial dyslipidemia. A genomic scan identified a region of linkage including LPL, and mutation screening identified the segregating variant. In the kindred, the variant shows high penetrance for a hypoalphalipoproteinemia phenotype, but is also associated with hypertriglyceridemia and elevated insulin levels. The strength of linkage was dependent on the combination of phenotype definition and model parameters, favoring the use of a MOD score approach. Most other studies of LPL have proceeded by mutation screening of randomly chosen individuals or selected affected probands; this is the first example identifying a segregating LPL mutation using direct linkage. 相似文献
30.
Telfer JF; Thomson AJ; Cameron IT; Greer IA; Norman JE 《Human reproduction (Oxford, England)》1997,12(10):2306-2312
Superoxide, an agent which attenuates the half-life of nitric oxide, is
metabolized and synthesized by superoxide dismutase (SOD) and xanthine
oxidase, respectively. Over the last few years much work has focused on the
role of nitric oxide in human parturition. The aim of this study was to
determine whether the onset of human parturition is associated with a
change in the expression of copper/zinc superoxide dismutase (Cu/Zn SOD),
manganese superoxide dismutase (Mn SOD) or xanthine oxidase within the
uterus. Samples of myometrium, placenta, decidua and fetal membranes were
obtained from women before and after the onset of labour at term.
Immunocytochemistry was used to localize Cu/Zn SOD, Mn SOD and xanthine
oxidase and measure SOD enzyme activity. Cu/Zn and Mn SOD-like
immunoreactivity was detected in syncytiotrophoblast cells, villous stromal
cells and endothelial cells of blood vessels in the placenta. In the
myometrium Cu/Zn and Mn SOD were localized to myocytes and endothelial
cells and to some vascular smooth muscle cells. In the fetal membranes we
observed staining for Cu/Zn SOD and Mn SOD in the amnion, chorion,
extravillous trophoblast and decidua. There was no difference in SOD enzyme
activity or staining intensity for SOD between different cell types before
and during labour. Xanthine oxidase immunoreactivity was identified in each
of the tissues examined and again there was no difference in immunostaining
in tissues obtained from women delivered before or after the onset of
labour. These results show that the pregnant uterus is capable of both
synthesizing and degrading superoxide and suggest that superoxide dismutase
and xanthine oxidase may play a role in the maintenance of uterine
quiescence during pregnancy, but not in the initiation of parturition.
相似文献