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   620篇
  免费   24篇
  国内免费   20篇
儿科学   24篇
基础医学   33篇
口腔科学   35篇
临床医学   47篇
内科学   136篇
皮肤病学   4篇
神经病学   15篇
特种医学   166篇
外科学   53篇
综合类   17篇
预防医学   50篇
眼科学   2篇
药学   49篇
  2篇
肿瘤学   31篇
  2023年   1篇
  2021年   1篇
  2020年   2篇
  2019年   1篇
  2018年   5篇
  2017年   2篇
  2016年   2篇
  2015年   4篇
  2014年   5篇
  2013年   9篇
  2012年   15篇
  2011年   10篇
  2010年   7篇
  2009年   13篇
  2008年   9篇
  2007年   22篇
  2006年   16篇
  2005年   6篇
  2004年   8篇
  2003年   5篇
  2002年   14篇
  2001年   4篇
  2000年   12篇
  1999年   16篇
  1998年   29篇
  1997年   27篇
  1996年   32篇
  1995年   29篇
  1994年   23篇
  1993年   25篇
  1992年   9篇
  1991年   12篇
  1990年   17篇
  1989年   43篇
  1988年   27篇
  1987年   35篇
  1986年   21篇
  1985年   34篇
  1984年   19篇
  1983年   20篇
  1982年   10篇
  1981年   8篇
  1980年   13篇
  1979年   11篇
  1978年   9篇
  1977年   13篇
  1976年   7篇
  1973年   1篇
  1969年   1篇
排序方式: 共有664条查询结果,搜索用时 15 毫秒
81.
We describe a patient in whom multiple cavitary lung nodules developed without infectious symptoms after treatment with bleomycin, cisplatin and vinblastine combination chemotherapy for metastatic testis cancer. Open lung biopsy demonstrated extensive granuloma formation without evidence of malignancy or infection. This report extends the spectrum of bleomycin pulmonary toxicity to include cavitary pulmonary nodules associated with granuloma formation.  相似文献   
82.
Six normal and 16 neoplastic colorectal specimens were examined with 8.5-MHz ultrasound (US). An articulated system facilitated precise spatial correlation between US and histologic sections. Images were blindly interpreted and then compared with histologic results. All six normal specimen showed five distinct echo layers and were distinguished from neoplastic specimens by all the observers. The central echogenic layer, corresponding to the submucosa, is useful in determining the depth of origin of a neoplasm and the presence of submucosal invasion. US had an accuracy of 92.5% in demonstrating invasion of the submucosa and 77% for invasion of the muscularis externa. For mucosal neoplasms with invasion through the muscularis externa and extension into the subserosal tissues, nearly 90% of US interpretations were correct. High-frequency US may be useful in determining the depth of invasion of mucosal tumors with respect to the submucosa and in differentiating mucosal from extramural masses.  相似文献   
83.
Urine-compatible polymer for long-term ureteral stenting   总被引:1,自引:0,他引:1  
Internal double-J ureteral stents were designed from a urine-compatible polymer (C-Flex), and 35 stents were placed in patients. The overall patency rate for the stents was 80%, with most stent failures occurring before 2 months; the follow-up period ranged from 2 to 16 months, with a mean follow-up for all stents of 5.0 months. Stents were considered patent at last follow-up only if they had been in place for at least 2 months. No migration or fracture of the stents occurred. Physical properties of urine-exposed stents were compared with those of virgin tubing and tubing exposed for 1 year to shelf conditions. Stent patency was optimized by increasing urine flow by increasing the patient's voluntary oral intake, administering prophylactic oral antibiotics, and avoiding placement of stents into grossly bloody or infected collecting systems.  相似文献   
84.
Meniscal tears of the knee: accuracy of MR imaging   总被引:39,自引:0,他引:39  
Crues  JV  d; Mink  J; Levy  TL; Lotysch  M; Stoller  DW 《Radiology》1987,164(2):445-448
Before surgery, 277 menisci in 144 knees were examined with magnetic resonance (MR) imaging. They were then examined directly with arthroscopy or arthrotomy. Menisci were graded on a scale of 1-3 according to the character of the intrameniscal MR imaging signal. At surgery, 137 of 154 (89%) menisci exhibiting only grade 1 or grade 2 signal were found to be normal. One hundred sixteen of 123 (94%) menisci exhibiting intrameniscal signal communicating with a meniscal articular surface (grade 3 signal) had tears. If only a grade 3 signal is considered consistent with meniscal tears, then MR findings and surgical findings agreed in 91.3% of menisci. MR imaging can separate surgically significant from nonsignificant meniscal lesions and is useful in the noninvasive preoperative screening of suspected meniscal tears.  相似文献   
85.
86.
Abstract. The purpose of this study was to investigate the effect of 2 growth factors, platelet-derived growth factor-BB (PDGF-BB) and insulin-like growth factor-1 (IGF-1) alone or in combination, on the adherence of human periodontal ligament fibroblast (PDL) to tetracycline HCI (TTC) conditioned and non-conditioned periodontally involved root surfaces. There were 80 root dentine chips from 80 patients, ranging from 35 to 70 years of age, each with one periodontally involved tooth requiring extraction. A root dentine chip was obtained from the subgingival surface opposite to the periodontal pocket of each extracted tooth. The dentine chips were randomly distributed into one of 8 groups. In group 1, PDL Fibroblasts were cultured and allowed to attach on the dentine surface. In group 2, PDL fibroblasts were cultured on a PDGF-BB pre-treated dentine surface and in group 3, they were cultured on a IGF-1 pre-treated dentine surface. In group 4, PDL fibroblasts were cultured on a dentine surface pretreated with a combination of PDGF-BB and IGF-1. In group 5, PDL fibroblasts were cultured and allowed to attach on the TTC conditioned dentine surfaces. In groups 6 and 7, surface of dentine chips were conditioned with TTC and then were treated with PDGF-BB or IGF-1 respectively, followed by placement of PDL fibroblast and cultured. In group 8, dentine surfaces were conditioned with TTC and then pre-treated with a combination of PDGF-BB and IGF-1 before the fibroblasts were cultured. After 24 h of incubation, the media was removed and samples were fixed and processed for SEM at magnifications of ×34, ×750, ×2000. Photographing and evaluation of samples was performed at ×750 in which fibroblast adherence was measured by counting cells within a standard test area. The results of the non-TTC conditioned root surfaces demonstrated a significant increase in fibroblasts adherence in the PDGF-BB and combination PDGF-BB/IGF-1 treatment groups (groups 2, 4) when compared to the control (group 1) as well as the TTC control (group 5). The combination of PDGF-BB/IGF-1 (group 4) did not significantly improve the adhesion of cells compared to PDGF-BB alone (group 2), but did significantly improve adhesion when compared to IGF-1 alone (group 3). There were no significant differences in cell morphology between the growth factor groups (groups 2, 3, 4) and control (group 1). In general, the cells demonstrated a fiat, stellate-shaped morphology. The results of the TTC conditioned root surfaces, showed a statistically significant increase of cellular adherence in the PDGF-BB group (group 6) when compared to the TTC control (group 5), similar to the non-TTC group (group 2). However, the morphology of the cells in groups 5, 6, 7, and 8 demonstrated generally a rounded or oval shape with only an occasional cell exhibiting a flat form, in the experimental system of this study, the inclusion of PDGF-BB on the surface of dentine chips increased the number of adhering PDL cells, and the addition of TTC conditioning had little effect except to change the morphology of adhering cells.  相似文献   
87.
88.
The relative contribution of socioeconomic, behavioural and biological factors operating in fetal and infant life, childhood and adulthood to risk for cardiovascular disease, respiratory diseases and non-insulin-dependent diabetes in middle age has become an important research issue. All 1142 babies born in Newcastle upon Tyne in May and June 1947 were recruited into a prospective cohort study of child health (the ‘Thousand Families’ study) and followed in great detail to the age of 15 y, with a brief further follow up at age 22 y. Children from poorer families were at greatest risk of severe respiratory tract infection in infancy. Children from professional and managerial families were on average taller and heavier throughout childhood than those from semi- and unskilled manual social classes. Repeated infections in early childhood greatly increased the risk of developing chronic respiratory disease by age 15 y. This paper outlines a new investigation designed to trace surviving members of this cohort and to chart the relationships between their socioeconomic circumstances, lifestyles, experiences and health from birth through to the present day. Existing data on socioeconomic circumstances and infections in infancy and childhood, infant nutrition, birthweight and physical development to age 22 y will be linked to information gained from a new study. This comprises a postal questionnaire survey of study members' adult health, socioeconomic circumstances and lifestyle, and a hospital based clinical examination including heart and lung function, glucose tolerance, blood lipids and anthropometric measurements at age 49–51 y. Out of a target sample of 979 people for whom sufficient data are available on the first year of life, 866 (88%) have been traced and 649 are still resident in the North of England. Those study members who have been traced are highly representative of the original cohort. The Thousand Families cohort provides a unique opportunity for detailed epidemiological study because of the wealth of data available on infant and childhood socioeconomic and family circumstances, all of which was collected prospectively. In addition, there has been comparatively little loss to follow-up since 1948.  相似文献   
89.
Gelfand  DW; Chen  YM; Ott  DJ 《Radiology》1987,162(3):829-834
Multiphasic examinations of 153 gastric abnormalities observed radiologically and endoscopically were reviewed to determine the efficacy of four radiologic techniques and of several common combinations of these techniques for examining the stomach. There were 68 gastric ulcers, 12 ulcer scars, 44 cases of gastritis including 27 with erosions, 24 benign neoplasms, and five malignancies. Double-contrast, compression, mucosal relief, and full-column techniques detected 82%, 65%, 62%, and 51%, respectively, of all lesions diagnosed with the complete multiphasic examinations. Results indicate that the greater the number of techniques employed, the more accurate the examination, with biphasic and multiphasic examinations detecting 9%-18% more lesions overall than simple single- or double-contrast studies.  相似文献   
90.
This study analyzed the calcium and phosphorus content of extracted tooth roots exposed to the in vivo oral environment. 20 teeth were obtained from 16 patients and divided into two groups of 10 teeth each. In group 1, the teeth had gingival probing depths of 5 mm or more, and teeth of group 2 had gingival recessions of 3 mm or more. Prior to extraction, the gingival margin location was recorded by placing a groove on the tooth surface. After extraction, the teeth were sectioned coronal-apically, air dried and coated with carbon. Energy dispersive X-ray spectra, excited in a scanning electron microscope, were analyzed to measure relative calcium and phosphorus contents and for calculation of their ratios. X-rays were collected from two positions on the sectioned root. Experimental positions were selected within the exposed portion of the roots of groups 1 and 2, and unexposed positions were selected from that portion of the same root with attached periodontal membrane. At each position, calcium and phosphorus content was measured at 4 depths into the root surface: in cementum, in dentin three-quarters of the distance to the pulp chamber, and at 2 locations in between on either side of the cemento-dentinal junction. Analysis of data demonstrated large variations in calcium and phosphorus content from surface to surface of individual teeth and from tooth to tooth in a subject. No statistically significant differences were found between experimental and unexposed locations. Calcium and phosphorus contents were greater in roots exposed to pockets when compared to roots exposed by recession at both experimental and unexposed locations.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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