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   710篇
  免费   55篇
  国内免费   22篇
耳鼻咽喉   1篇
儿科学   49篇
妇产科学   6篇
基础医学   83篇
口腔科学   42篇
临床医学   61篇
内科学   120篇
皮肤病学   28篇
神经病学   15篇
特种医学   218篇
外科学   29篇
综合类   34篇
预防医学   34篇
眼科学   5篇
药学   20篇
肿瘤学   42篇
  2018年   5篇
  2017年   5篇
  2016年   8篇
  2015年   8篇
  2014年   13篇
  2013年   8篇
  2012年   4篇
  2011年   7篇
  2010年   18篇
  2009年   20篇
  2008年   18篇
  2007年   12篇
  2006年   14篇
  2005年   8篇
  2004年   11篇
  2003年   9篇
  2002年   5篇
  2001年   11篇
  2000年   10篇
  1999年   13篇
  1998年   39篇
  1997年   44篇
  1996年   41篇
  1995年   37篇
  1994年   24篇
  1993年   31篇
  1992年   24篇
  1991年   17篇
  1990年   13篇
  1989年   23篇
  1988年   28篇
  1987年   44篇
  1986年   25篇
  1985年   16篇
  1984年   8篇
  1983年   12篇
  1982年   14篇
  1981年   20篇
  1980年   17篇
  1979年   8篇
  1978年   6篇
  1977年   9篇
  1976年   21篇
  1975年   10篇
  1934年   4篇
  1933年   3篇
  1932年   2篇
  1930年   3篇
  1927年   4篇
  1926年   4篇
排序方式: 共有787条查询结果,搜索用时 31 毫秒
51.
Mann  LC; Hawes  DR; Ghods  M; Bednar  EJ; Potchen  EJ 《Radiology》1987,164(1):121-122
Data obtained on 426 consecutive patients referred to a breast center by 122 physicians, including family practitioners, general surgeons, and other specialists, showed that the obstetricians-gynecologists referred the greatest average number of patients per physician, with more than 50% of these referrals for screening mammography. Internists referred fewer patients by nearly a factor of ten, with only one-third of these patients referred for screening mammography. Internists may be the weakest link in the utilization of screening mammography.  相似文献   
52.
53.
Cystic fibrosis (CF), a genetic disorder, is characterized by chronic pulmonary infection/inflammation which leads to respiratory failure. The presence of anti-neutrophil cytoplasmic autoantibodies (ANCA) has previously been observed in the sera of patients with CF. In view of the known relationship of ANCA with primary vasculitis and of their putative pathogenetic role in these disorders, we studied the presence, specificity and isotype of ANCA and their clinical associations in 66 adult CF patients. None of the 66 CF samples had autoantibodies to the major ANCA antigens, proteinase 3 or myeloperoxidase. However, 60/66 (91%) CF samples contained IgG and 55/66 (83%) IgA, autoantibodies to bactericidal/permeability increasing protein (BPI), a recently characterized ANCA specificity. All the IgA anti-BPI-positive samples were also IgG anti-BPI-positive. The autoantibody specificity was confirmed by inhibition assay and immunoblotting of CF sera against a neutrophil granule preparation. Furthermore, in this cross-sectional study, anti-BPI levels were inversely correlated with the observed reductions in FEV1 and FVC (IgA anti-BPI and FEV1: r = 0.508, <it>p</it> &lt; 0.0001), and both IgG and IgA anti-BPI levels were higher in CF patients with secondary vasculitis (<it>n</it> = 6) than in those without (<it>p</it> &lt; 0.05). ANCA with specificity for BPI were present in the majority of CF sera in this study and autoimmune processes may be associated with the development of pulmonary injury in CF.   相似文献   
54.
Felty's syndrome (FS) (rheumatoid arthritis with neutropenia and splenomegaly) has a poor prognosis, largely because of the high risk of severe infection. Granulocyte colony-stimulating factor (G-CSF) is an emerging treatment for chronic neutropenia. We prospectively monitored its use in eight patients with recurrent infections or who required joint surgery. Significant side-effects were documented in five, including nausea, malaise, generalized joint pains, and in one patient, a vasculitic skin rash. In two patients treatment had to be stopped, and in these cases G-CSF had been started at full vial dosage (300 micrograms/ml filgrastim or 263 micrograms/ml lenograstim) alternate days or daily. G-CSF treatment was continued in three patients by restarting at reduced dose, and changing the proprietary formulation. G- CSF raised the neutrophil count, reduced severe infection, and allowed surgery to be performed. A combined clinical and laboratory index suggested that long-term treatment (up to 3.5 years) did not exacerbate the arthritis. Once on established treatment, it may be possible to use smaller weekly doses of G-CSF to maintain the same clinical benefit. One of the three patients whose FS was associated with a large granular T-cell lymphocytosis showed a reduction in this subset of lymphocytes during G-CSF treatment.   相似文献   
55.
Growth factors have been identified as the primary cause of osteoinduction in bone healing. Transforming growth factor beta (TGF- beta) has been shown to promote bone formation and is present in bone in high quantities. The aims of the present study were to isolate TGF- beta from human bone, demonstrate its biologic activity, and analyze the effects of conventional sterilization techniques on activity. Bone, obtained from femoral heads of five patients (mean age, 70 years) was ground, demineralized, and freeze-dried, and samples from each patient were divided into three groups: no treatment, sterilization with 1.60 to 1.94 Mrad of 60Co irradiation, and sterilization with ethylene oxide (ETO). Carrier-free recombinant TGF-beta control was also treated and was totally inactivated by ETO but not by irradiation (p < 0.01). TGF- beta activity in demineralized bone was not significantly diminished (p > 0.1) by either sterilization procedure, and substantial amounts of active TGF-beta were recovered in all bone samples: 1.04 +/− 0.77 ng per mg of protein in irradiated samples, 0.67 +/− 0.26 ng per mg in ETO- treated samples, and 1.04 +/− 0.33 in untreated samples, respectively (mean +/− SD). Although a recent report demonstrated that the osteoinductive activity of bone morphogenetic protein in bone powder is diminished considerably by ETO and by 2.5 Mrad of irradiation sterilization of bone powder, these data demonstrate that TGF-beta activity, with its osteoinductive properties, was not destroyed in more coarsely ground, demineralized bone by ETO or by lower doses of irradiation. These findings support the use of human bone allografts in clinical instances involving impaired bone formation.  相似文献   
56.
白介素与溃疡性结肠炎   总被引:17,自引:1,他引:17  
近年来对白介素(interleukin,IL)和溃疡性结肠炎(ulcerative colitis,UC)的研究取得了很大进展,我们通过总结整理以前有关IL和UC的文献,概括出IL的产生和在UC发病及病理变化中的作用机制:IL-1直接介导了UC初期阶段炎症的发生:IL-8、IL-6直接促进炎性细胞过度分泌和/或抑制了炎性细胞的凋亡,IL-2分泌减少导致免疫系统内细胞间网络调节失衡, 使局部炎症介质和自由基释放,引起细胞毒作用,IL主要通过影响机体整体和/或局部免疫系统的功能介导UC的产生,并与UC的迁延难愈和反复发作有关.  相似文献   
57.

INTRODUCTION

Blood is a scarce and expensive product. Although it may be life-saving, in recent years there has been an increased emphasis on the potential hazards of transfusion as well as evidence supporting the use of lower transfusion thresholds. Orthopaedic surgery accounts for some 10% of transfused red blood cells and evidence suggests that there is considerable variation in transfusion practice.

PATIENTS AND METHODS

NHS Blood and Transplant, in collaboration with the Royal College of Physicians, undertook a national audit on transfusion practice. Each hospital was asked to provide information relating to 40 consecutive patients undergoing elective, primary unilateral total hip replacement surgery. The results were compared to indicators and standards.

RESULTS

Information was analysed relating to 7465 operations performed in 223 hospitals. Almost all hospitals had a system for referring abnormal pre-operative blood results to a doctor and 73% performed a group-and-save rather than a cross-match before surgery. Of hospitals, 47% had a transfusion policy. In 73%, the policy recommended a transfusion threshold at a haemoglobin concentration of 8 g/dl or less. There was a wide variation in transfusion rate among hospitals. Of patients, 15% had a haemoglobin concentration less than 12 g/dl recorded in the 28 days before surgery and 57% of these patients were transfused compared to 20% with higher pre-operative values. Of those who were transfused, 7% were given a single unit and 67% two units. Of patients transfused two or more units during days 1–14 after surgery, 65% had a post transfusion haemoglobin concentration of 10 g/dl or more.

CONCLUSIONS

Pre-operative anaemia, lack of availability of transfusion protocols and use of different thresholds for transfusion may have contributed to the wide variation in transfusion rate. Effective measures to identify and correct pre-operative anaemia may decrease the need for transfusion. A consistent, evidence-based, transfusion threshold should be used and transfusion of more than one unit should only be given if essential to maintain haemoglobin concentrations above this threshold.  相似文献   
58.
59.
60.
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