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   343篇
  免费   30篇
  国内免费   11篇
耳鼻咽喉   1篇
儿科学   8篇
妇产科学   4篇
基础医学   47篇
口腔科学   7篇
临床医学   36篇
内科学   82篇
皮肤病学   6篇
神经病学   5篇
特种医学   87篇
外科学   32篇
综合类   14篇
预防医学   13篇
眼科学   3篇
药学   24篇
肿瘤学   15篇
  2022年   3篇
  2021年   3篇
  2019年   6篇
  2018年   6篇
  2016年   8篇
  2015年   6篇
  2014年   5篇
  2013年   9篇
  2012年   16篇
  2011年   3篇
  2010年   12篇
  2009年   8篇
  2008年   10篇
  2007年   9篇
  2006年   6篇
  2005年   6篇
  2004年   11篇
  2003年   6篇
  2002年   3篇
  2001年   4篇
  2000年   9篇
  1999年   9篇
  1998年   9篇
  1997年   12篇
  1996年   9篇
  1995年   8篇
  1994年   12篇
  1993年   14篇
  1992年   6篇
  1991年   7篇
  1990年   8篇
  1989年   9篇
  1988年   12篇
  1987年   12篇
  1986年   18篇
  1985年   5篇
  1984年   3篇
  1983年   6篇
  1982年   5篇
  1981年   5篇
  1980年   6篇
  1979年   6篇
  1978年   10篇
  1977年   10篇
  1976年   3篇
  1975年   3篇
  1974年   5篇
  1973年   9篇
  1971年   4篇
  1970年   3篇
排序方式: 共有384条查询结果,搜索用时 15 毫秒
71.
The lumbar spines of 22 patients were examined for disc degeneration by magnetic resonance imaging (MRI) and by discography. The results from 50 intervertebral discs visualised by both techniques were independently assessed and graded on a five-point scale from normality to gross degeneration and then compared. In 44 discs the results agreed. Of the six discs which gave differing results, four discrepancies were due to observer error and two to incorrect placement of the discographic needle. MRI was shown to be more accurate than discography in the diagnosis of disc degeneration. It has several major advantages, which should make it the investigation of choice.  相似文献   
72.
Stahl  CP; Zucker-Franklin  D; McDonald  TP 《Blood》1986,67(2):421-428
Immune thrombocytopenias are usually associated with normal or increased numbers of megakaryocytes in the marrow. Therefore, the mechanism(s) responsible for the destruction of circulating platelets may not affect megakaryocytes in the same way. One of the possibilities which could account for the differential effect on the cells would be the development of antibodies to components of platelet membranes which are not exposed on the surface of all megakaryocytes. To investigate this possibility, a rabbit antiserum specific for mouse platelets was tested against fresh and cultured mouse megakaryocytes by indirect immunofluorescence. This antiserum cross-reacted with 46% of fresh murine megakaryocytes and 54% of cultured megakaryocytes. Phase- contrast microscopy revealed the reacting megakaryocytes to be fully granulated with irregular contours and in the process of releasing platelets. Nonreactive megakaryocytes demonstrated smooth contours and lacked morphological evidence of thrombocytopoiesis. Electron microscopy showed that only in megakaryocytes (MK) with an irregular contour had the demarcation membrane system (DMS) reached continuity with the plasma membrane. Ultrastructural analysis of megakaryocytes from patients with ITP showed approximately 25% to 50% of megakaryocytes without evidence of injury, whereas 50% to 75% had extensive damage. In undamaged cells, platelet territories had not yet reached the peripheral zone. The DMS of damaged megakaryocytes opened to the exterior elaborating platelets. The observations suggested that some platelet antibodies react only with megakaryocytes which have reached the stage of thrombocytopoiesis. Relevant target antigens may not be exposed on all megakaryocytes before cytoplasmic fragmentation occurs.  相似文献   
73.
Three commercial vessel dilators and a dilator of an improved design were tested during percutaneous catheterization in 16 mongrel dogs to evaluate arterial damage produced with their use. The results indicate that, although all dilators often produce arterial damage, the improved design produced much less damage. In addition, lesions were less severe overall. The dilator has been safely and successfully used in patients for percutaneous vessel catheterization for the past 30 years at the authors' institution.  相似文献   
74.
Synovial chondromatosis of the pisotriquetral joint.   总被引:1,自引:0,他引:1       下载免费PDF全文
  相似文献   
75.
76.
目的定期随访评价ISOLA器械治疗小儿脊柱侧凸.方法41例小儿脊柱侧凸患儿,特发性脊柱侧凸32例,神经肌肉性脊柱侧凸5例,其他类型的脊柱侧凸4例,术前、术中、术后均摄X线片,记录Cobb角,顶椎的移位及旋转,躯干偏离中线程度.结果Cobb角术前平均为66°,术后1年为36°,术后2年为36°.1年后,所有患儿的脊柱均完全融合.顶椎的偏离改善了14mm.躯干偏离改善了5mm.特发性脊柱侧凸患儿1年后有基本的正常活动.术后4例出现并发症,1例深部感染,1例骶尾部褥疮,1例横钩脱落,1例L3椎弓根螺丝钉脱落.结论目前有多种后路器械治疗小儿脊柱侧凸.严格掌握手术指征及ISOLA的原理,该术式能获得较为满意的疗效.  相似文献   
77.
This study was conducted to analyse the effect of childhood-onset diabetes mellitus on adult height. The height at time of diagnosis of 35 children with insulin-dependent diabetes mellitus (IDDM) was compared with growth reference data. Predictions of the adult height were made at the time of diagnosis using the target height and the Tanner-Whitehouse II method. The adult height was compared with both the predicted values and the height of healthy adults. The height at time of diagnosis of the prepubertal children was increased compared with growth reference data, in contrast to pubertal children who had normal heights. Only the prepubertal boys were taller at time of diagnosis. The adult height of the prepubertal patients was taller than growth reference data. The mean adult height in all patients did not differ significantly from the predicted heights. In conclusion, the increased height at the start of IDDM in prepubertal children persists until adulthood.  相似文献   
78.
Effects of short-term hypoxia on platelet counts of mice   总被引:3,自引:0,他引:3  
McDonald  TP; Cottrell  M; Clift  R 《Blood》1978,51(1):165-175
Recent studies have shown that long-term hypoxia causes decreased platelet counts in mice and short-term hypoxia increased platelet counts. In an attempt to explain the mechanism that increases platelet counts of mice after exposure to short-term hypoxia, we measured platelet counts, total circulating platelet counts (TCPC), total circulating platelet masses (TCPM), percentages of 35S incorporation, and platelet sizes. Platelet counts, as well as TCPC and TCPM of mice, increased after 1-3 days of hypoxia, but these values were decreased after 6-7 days of hypoxia. Although platelet counts were increased in hypoxic mice, the percentage 35S incorporation into platelets and platelet sizes did not show a concurrent increase. After 6 days of hypoxia, average platelet diameters began to increase as platelet counts decreased. Splenic release did not account for the increase in platelet counts of mice after short-term hypoxia. It seems possible, therefore, that megakaryocytes "shed" platelets into the circulation in response to hypoxia. The platelets that enter the circulation in response to short-term hypoxia are smaller and incorporate less 35S than platelets that are produced in response to acute thrombocytopenia.  相似文献   
79.
The growth fraction of tumors from patients with non-Hodgkin's lymphomas (NHL) has been shown to correlate with survival in retrospective studies. The growth fraction can be evaluated using immunohistochemical techniques employing the Ki-67 monoclonal antibody (MoAb) that marks a nuclear protein present in cycling cells. The purpose of this study was to evaluate the clinical utility of the Ki-67 MoAb for predicting survival. Using a prospective trial design in a multi-institutional cooperative trials group, the proliferative index, clinical outcome, and statistical correlations were independently assessed for previously untreated patients with advanced stages of intermediate- and high-grade histologies of NHL treated on Southwest Oncology Group study (SWOG 8516, Intergroup 0067). The proportion of Ki- 67-positive cells was determined on snap-frozen thin tissue sections. A proliferative index of 80% or greater, as determined from prior retrospective studies, identified a group of patients (18%) who had a poor outcome. Overall survival was significantly reduced in these patients with a high Ki-67-associated proliferative index compared with those with a low proliferative index (P = .001). One-year survival estimates were 82% (low proliferative index) versus 18% (high proliferative index). A multivariate regression analysis incorporating commonly used clinical prognostic features confirmed the independent effect of proliferation on survival (relative risk estimate 5.9; 95% confidence interval, 2.2, 16.1). The Ki-67 MoAb identifies a group of patients with rapidly fatal NHL for whom currently available chemotherapy is inadequate.  相似文献   
80.
Dynamic exercise therapy in rheumatoid arthritis: a systematic review   总被引:7,自引:2,他引:7  
The aim of this systematic review was to determine the effectiveness of dynamic exercise therapy in improving joint mobility, muscle strength, aerobic capacity and daily functioning in patients with rheumatoid arthritis (RA). In addition, possible unwanted effects such as an increase in pain, disease activity and radiological progression were studied. A computer-aided search of the MEDLINE, Embase and SCISEARCH databases was performed to identify controlled trials on the effect of exercise therapy. Randomized trials were selected on the effect of dynamic exercise therapy in RA patients with an exercise programme fulfilling the following criteria: (a) intensity level such that heart rates exceeded 60% of maximal heart rate during at least 20 min; (b) exercise frequency > or = 2 a week; and (c) duration of intervention > or = 6 weeks. Two blinded reviewers independently selected eligible studies, rated the methodological quality and extracted data. Six out of 30 identified controlled trials met the inclusion criteria. Four of the six included studies fulfilled > or = 7/10 methodological criteria. Because of heterogeneity in outcome measures, data could not be pooled. The results suggest that dynamic exercise therapy is effective in increasing aerobic capacity and muscle strength. No detrimental effects on disease activity and pain were observed. The effects of dynamic exercise therapy on functional ability and radiological progression are unclear. It is concluded that dynamic exercise therapy has a positive effect on physical capacity. Research on the long-term effect of dynamic exercise therapy on radiological progression and functional ability is needed.   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