首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   960篇
  免费   103篇
  国内免费   3篇
耳鼻咽喉   2篇
儿科学   43篇
妇产科学   34篇
基础医学   124篇
口腔科学   30篇
临床医学   117篇
内科学   182篇
皮肤病学   11篇
神经病学   106篇
特种医学   35篇
外科学   144篇
综合类   14篇
一般理论   2篇
预防医学   48篇
眼科学   8篇
药学   73篇
肿瘤学   93篇
  2022年   5篇
  2021年   15篇
  2020年   15篇
  2019年   12篇
  2018年   33篇
  2017年   19篇
  2016年   13篇
  2015年   25篇
  2014年   25篇
  2013年   24篇
  2012年   49篇
  2011年   51篇
  2010年   29篇
  2009年   28篇
  2008年   54篇
  2007年   46篇
  2006年   53篇
  2005年   41篇
  2004年   32篇
  2003年   26篇
  2002年   30篇
  2001年   27篇
  2000年   38篇
  1999年   35篇
  1998年   27篇
  1997年   16篇
  1996年   20篇
  1995年   11篇
  1994年   14篇
  1993年   6篇
  1992年   25篇
  1991年   22篇
  1990年   17篇
  1989年   17篇
  1988年   15篇
  1987年   11篇
  1986年   5篇
  1985年   16篇
  1984年   14篇
  1983年   5篇
  1982年   13篇
  1981年   7篇
  1980年   9篇
  1979年   9篇
  1978年   5篇
  1973年   6篇
  1972年   11篇
  1971年   6篇
  1970年   5篇
  1967年   5篇
排序方式: 共有1066条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
5.
The aim of this study was to determine the self-reported preventive oral health related behaviours of dentally anxious schoolchildren. 1103 children participated in the study, mean age 14 years (SD 0.35 years), and the prevalence of high dental anxiety was 7.1 per cent (95 per cent confidence interval = 5.6 per cent, 8.6 per cent). Children with high self reported dental anxiety were more likely to defer, cancel and or not attend dental appointments. In addition, for this group the last dental visit was more likely to be as a result of pain and less likely to have been for a dental examination only. Overall dentally anxious children did not help themselves by keeping their teeth clean. Fluorides were infrequently used by all the children, and only 12 per cent of all who participated in the study used fluoride supplements regularly. In this context it is not surprising that no differences in present or past use of fluoride supplements could be determined between high and low/moderate dental anxiety groups. The high dental anxiety group spend significantly more (median = 50p) on sweets per day and drank more cans of fizzy drinks (median = 2) compared with the low/moderate anxiety groups. These effects were significant after taking into account social class and gender differences. It was clear from the study that even when social class and gender are taken into account the children with high dental anxiety were not helped by their relatively poor attitudes towards preventing disease in their own mouths.  相似文献   
6.
Summary A retrospective evaluation of the prognostic value of different parameters available in patients affected by glial tumours and submitted to serial stereotactic biopsy is presented. The series investigated includes thirty-three untreated patients with proven brain gliomas submitted to stereotactic biopsy. All patients have been clinically and neuroradiologically monitored for three years. The factors investigated belong either to the preoperative data (clinical history and symptomatology, CT pattern and volume of the lesion) or to histological and biological data obtained after the stereotactic biopsy. The results suggest the need of a multimodal prognostic evaluation in glial tumours and particularly stressed is the accuracy of prognostic indications derived from cell kinetic studies.Presented at the European Congress of Neurosurgery, Barcelona, September 1987.  相似文献   
7.
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   
8.
Prader–Willi syndrome and Angelman syndrome are associated with parent-of-origin-specific abnormalities of chromosome 15q11–q13, most frequently a deletion of an ~4-Mb region. Because of genomic imprinting, paternal deficiency of this region leads to PWS and maternal deficiency to AS. Additionally, this region is frequently involved in other chromosomal rearrangements including duplications, triplications, or supernumerary marker formation. A detailed physical map of this region is important for elucidating the genes and mechanisms involved in genomic imprinting, as well as for understanding the mechanism of recurrent chromosomal rearrangments. An initial YAC contig extended from D15S18 to D15S12 and was comprised of 23 YACs and 21 STSs providing an average resolution of about one STS per 200 kb. To close two gaps in this contig, YAC screening was performed using two STSs that flank the gap between D15S18 and 254B5R and three STSs located distal to the GABRA5–149A9L gap. Additionally, we developed 11 new STSs, including seven polymorphic markers. Although several groups have developed whole-genome genetic and radiation hybrid maps, the depth of coverage for 15q11–q13 has been somewhat limited and discrepancies in marker order exist between the maps. To resolve the inconsistencies and to provide a more detailed map order of STSs in this region, we have constructed an integrated YAC STS-based physical map of chromosome 15q11–q13 containing 118 YACs and 118 STSs, including 38 STRs and 49 genes/ESTs. Using an estimate of 4 Mb for the size of this region, the map provides an average STS spacing of 35 kb. This map provides a valuable resource for identification of disease genes localized to this region as well as a framework for complete DNA sequencing.  相似文献   
9.
Endothelin receptor expression in human decidua   总被引:3,自引:1,他引:3  
The endothelins are signalling peptides that act via two receptors, ET(A) and ET(B). In the human endometrium, endothelin receptors have been demonstrated in glands and stroma and have been shown to vary during the course of the menstrual cycle. The present study was undertaken to determine whether or not expression of endothelin receptors changes during pregnancy or after administration of exogenous progestagens. The expression of the receptors was correlated with the appearance of basement membrane components during decidualization of the endometrial stroma. Decidual specimens (n = 15) were obtained during the first trimester of pregnancy and 10 at term. Sixteen pairs of endometrial biopsies were obtained from women with menorrhagia before and after exposure to exogenous progestagens. A total of 15 hysterectomy specimens were used as controls for the expression of stromal basement membrane proteins in the absence of decidualization. Autoradiography was carried out with selective ligands for ET(A) ([125I]-PD 151242) and ET(B) ([125I]-BQ3020). The distribution of ligand binding was then compared with the distribution of laminin alpha2 light chain and collagen IV. ET(A), ET(B), laminin alpha2 light chain, and collagen IV were expressed in stromal decidual cells in the first trimester of pregnancy. ET(B) was also found on endometrial glandular epithelium. Quantitative macro-autoradiography and multiple regression analysis demonstrated a highly significant positive correlation (P < 0.001) between expression of ET(B) and laminin alpha2 light chain. In the third trimester qualitative examination suggested a reduction of ET(A) in the stroma. Progestagen-induced decidua exhibited a similar pattern to that found in first trimester decidua. This study has demonstrated up-regulation of ET(B) during the progesterone- dependent process of decidualization and suggests a paracrine or autocrine role for endothelins in the decidua.   相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号