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   839篇
  免费   74篇
  国内免费   6篇
耳鼻咽喉   6篇
儿科学   50篇
妇产科学   25篇
基础医学   80篇
口腔科学   15篇
临床医学   82篇
内科学   219篇
皮肤病学   1篇
神经病学   48篇
特种医学   150篇
外科学   40篇
综合类   31篇
预防医学   57篇
眼科学   35篇
药学   25篇
中国医学   1篇
肿瘤学   54篇
  2021年   4篇
  2020年   2篇
  2019年   4篇
  2018年   13篇
  2017年   8篇
  2016年   11篇
  2015年   12篇
  2014年   21篇
  2013年   31篇
  2012年   19篇
  2011年   21篇
  2010年   19篇
  2009年   12篇
  2008年   26篇
  2007年   43篇
  2006年   37篇
  2005年   24篇
  2004年   27篇
  2003年   29篇
  2002年   29篇
  2001年   31篇
  2000年   22篇
  1999年   34篇
  1998年   33篇
  1997年   34篇
  1996年   40篇
  1995年   32篇
  1994年   37篇
  1993年   26篇
  1992年   13篇
  1991年   26篇
  1990年   23篇
  1989年   16篇
  1988年   20篇
  1987年   18篇
  1986年   19篇
  1985年   18篇
  1984年   11篇
  1983年   14篇
  1982年   4篇
  1981年   11篇
  1980年   5篇
  1979年   4篇
  1978年   2篇
  1977年   11篇
  1976年   5篇
  1975年   2篇
  1971年   2篇
  1969年   3篇
  1955年   2篇
排序方式: 共有919条查询结果,搜索用时 31 毫秒
91.
Tumor‐infiltrating lymphocytes in colorectal cancer (CRC) predict better survival. However, associations between T‐lymphocyte count in histologically normal tissues from patients with CRC and survival remain uncertain. We examined associations of CD3+ T‐cells in colorectal tumor and histologically normal tissues with CRC‐specific and all‐cause mortality in the prospective Iowa Women's Health Study. Tissue microarrays were constructed using paraffin‐embedded colorectal tissue samples from 464 women with tumor tissues and 314 women with histologically normal tissues (55–69 years at baseline) diagnosed with incident CRC from 1986 to 2002 and followed through 2014 (median follow‐up 20.5 years). Three tumor and two histologically normal tissue cores for each patient were immunostained using CD3+ antibody and quantified, and the counts were averaged across the cores in each tissue. Cox proportional hazards regression estimated hazard ratios (HR) and 95% confidence interval (CI) for CRC‐specific and all‐cause mortality. After adjustment for age at diagnosis, body mass index, smoking status, tumor grade, and stage, HRs (95% CI) for the highest versus lowest tertile of tumor CD3+ score were 0.59 (0.38–0.89) for CRC‐specific mortality and 0.82 (0.63–1.05) for all‐cause mortality; for histologically normal CD3+ score, the corresponding HRs (95% CI) were 0.47 (0.19–1.17) and 0.50 (0.27–0.90), respectively. The CD3+ score combining the tumor and histologically normal scores was inversely associated with CRC‐specific and all‐cause mortality. Although the association between tumor CD3+ score and all‐cause mortality was not significant, both higher CD3+ T‐lymphocyte counts in tumor and histologically normal scores tended to be associated with lower CRC‐specific and all‐cause mortality.  相似文献   
92.
BACKGROUND: Vascular lesions have become more evident in human immunodeficiency virus type 1 (HIV)-infected patients as the result of earlier diagnosis, improved treatment, and longer survival. Aortic root dilation in HIV-infected children has not previously been described. This study was undertaken to determine the prevalence of aortic root dilation in HIV-infected children and to evaluate some of the potential pathogenic mechanisms. METHODS: Aortic root measurements were incorporated into the routine echocardiographic surveillance of 280 children of HIV-infected women: an older cohort of 86 HIV-infected children and a neonatal cohort of 50 HIV-infected and 144 HIV-uninfected children. RESULTS: By repeated-measures analyses, mean aortic root measurements were significantly increased in HIV-infected children versus HIV-uninfected children (P values of < or =.04 and < or =.005 at 2 and 5 years of age, respectively, for aortic annulus diameter, sinuses of Valsalva, and sinotubular junction). Heart rate, systolic blood pressure, stroke volume, hemoglobin, and hematocrit were not significantly associated with aortic root size. Left ventricular dilation, increased serum HIV RNA levels, and lower CD4 cell count measurements were associated with aortic root dilation at baseline. CONCLUSIONS: Mild and nonprogressive aortic root dilation was seen in children with vertically transmitted HIV infection from 2 to 9 years of age. Aortic root size was not significantly associated with markers for stress-modulated growth; however, aortic root dilation was associated with left ventricular dilation, increased viral load, and lower CD4 cell count in HIV-infected children. As prolonged survival of HIV-infected patients becomes more prevalent, some patients may require long-term follow-up of aortic root size.  相似文献   
93.
Antineutrophil cytoplasmic autoantibodies with specificity for myeloperoxidase (MPO) were found in 53 patient sera that were routinely submitted for antineutrophil cytoplasmic antibody determination. Based on clinical and histologic criteria, 15 of these 53 patients were classified as having systemic necrotizing vasculitis of the polyarteritis group, 11 patients were classified as having Wegener's granulomatosis (WG), and 14 were classified as having idiopathic crescentic glomerulonephritis. The remaining 13 patients did not fulfill the diagnostic criteria for these disorders, although most of these patients had clinical symptoms compatible with these disorders. While all patients with WG had renal involvement, only 4 of the 15 patients with systemic necrotizing vasculitis of the polyarteritis group had glomerulonephritis. The sensitivity of autoantibodies to MPO for either systemic necrotizing vasculitis of the polyarteritis group, WG, or idiopathic crescentic glomerulonephritis was further tested in all our patients with these disorders (n = 104). Twenty-seven of 104 patients had autoantibodies to MPO. Furthermore, 69 of the remaining 77 patients had autoantibodies specific for the 29-kd serine protease, which has been reported to be specifically associated with WG. Sera from 8 patients were negative for either of these antibodies (92% sensitivity of autoantibodies to MPO and/or the 29-kd serine protease). The specificity of autoantibodies to MPO for either systemic necrotizing vasculitis of the polyarteritis group, WG, or idiopathic crescentic glomerulonephritis was also tested in selected groups of patients who had closely related diseases. Two of 144 patients had autoantibodies to MPO (specificity 99%).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
94.
BACKGROUND: IgG subclasses of autoantibodies differ in their potential to induce an inflammatory response as they interact differentially with complement and Fcgamma receptors. METHODS: The IgG subclass distribution of anti-nucleohistone and anti-dsDNA antibodies was analysed longitudinally in patients with systemic lupus erythematosus before and at the moment of an extra-renal (n=23) or a renal relapse (n=l7). Kidney biopsy specimens of patients with a renal relapse were analysed for IgG subclass deposition. RESULTS: IgG1 anti-nucleohistone and IgG1 anti-dsDNA antibodies were present in plasma of 39 out of 40 patients. At the moment of a relapse, IgG2 and IgG3 anti-nucleohistone and IgG2 anti-dsDNA antibodies were more frequently present in patients with renal disease compared with those with extra-renal disease. Increases in levels of IgG1 anti-dsDNA were observed in 10 out of 11 patients prior to a renal relapse but only 10 out of 22 patients with an extra-renal relapse (91 vs 45%, P=0.02). Rises in IgG2 anti-dsDNA occurred at an equally low rate prior to both renal and extra-renal relapses. A rise in IgG2 anti-nucleohistone antibodies preceded a renal relapse in eight of 11 patients and an extra-renal relapse in only four out of 22 patients (73 vs 18%, P=0.006). In kidney biopsies all IgG subclasses could be detected. IgG1 and IgG2 subclass antibodies to nucleohistone and to dsDNA are the predominant subclasses found in plasma of lupus patients with renal disease. CONCLUSIONS: The frequent occurrence of a rise in IgG2 anti-nucleohistone and IgG1 anti-dsDNA in patients prior to a renal relapse suggests that, besides IgG1 subclass autoantibodies, IgG2 subclass antibodies to nucleohistone have a particular pathophysiological role in lupus nephritis.  相似文献   
95.
96.
Purpose: Causes of low vision in the Netherlands may have changed over time. The purpose of this study is to assess trends over the last two decades. Methods: Socio‐demographic and medical data, including ophthalmic diagnosis and inheritance patterns for 2843 children with low vision (0–21 years; 50% representation) referred to a Dutch institute for low vision (Bartiméus) over a 21‐year period between 1988 and 2009, were included in the analysis. For the 19 most common diagnoses, inheritance and presence of mental impairment, trend analyses were performed with logistic regression models; odds ratios (OR) for a 10‐year time span were reported. Results: Cerebral visual impairment (CVI) was found in 27.2% (97% mental impairment), albinism in 8.0%. Over time, nystagmus (6.6%; OR = 1.42), retinitis pigmentosa (2.9%; OR = 1.61), cone‐rod dystrophy (2.6%; OR = 1.98) and hyperopia (2.0%; OR = 3.66) increased significantly. Cataract (4.9%; OR = 0.64), aniridia (1.6%; OR = 0.42) and retinopathy of prematurity (ROP; 2.0%; OR = 0.45) decreased significantly. There was a significant increase in genetic disorders (41.0%; OR = 1.49) and in co‐occurrence of mental impairment (52.2% OR = 1.16). Conclusion: In the last two decades, treatable or preventable disorders (such as cataract and ROP) have become a less common cause of low vision in children. However, the prevalence of complex (genetic) and untreatable disorders (CVI) has taken its place, as a result of increased survival of preterm and low birth weight children and improved diagnostic possibilities. Knowledge of the prevalence of low vision, its causes and trends over time may help policy makers to define effective intervention strategies and to monitor its impact.  相似文献   
97.
98.
99.
The involvement of the erythropoietin (EPO), plasminogen activator inhibitor type I (PAI1), and multi-drug resistance (MDR2) genes located in chromosomal region 7q21-22 was studied in patients with myeloid disorders and with or without a chromosome 7 abnormality. Separated blood mononuclear cells and granulocytes from 21 patients were used in restriction fragment length polymorphism (RFLP) studies with gene- specific DNA probes. A marked weakness of one of the allelic bands was observed in granulocyte-derived DNA from heterozygous patients with monosomy 7. In four patients with a partial deletion of chromosome 7 long arm (7q-), marked weakness of an allelic band was observed in granulocyte-derived DNA with PAI1 probe (four heterozygous patients) and MDR2 probe (one heterozygous patient), implying deletion of these genes. In contrast, the EPO gene was not deleted in these patients, as demonstrated by the presence of two allelic bands of equal strength in granulocyte-derived DNA (two patients) or by gene dosage estimation (two patients). Two allelic bands of equal strength were also observed in three heterozygous patients with an arbitrary probe (pKV13) located in 7cen-q21.3. Unexpected hemizygosity or hybridization bands were not observed in any patient. We conclude that PAI1 and MDR2 are located distally of EPO in 7q22, and that none of these genes is commonly rearranged in myeloid disorders. The chromosome 7 long arm deletion breakpoint is located in a relatively narrow segment between the PAI1 and EPO genes in different patients. The deletion may involve a specific site in DNA, since the genetic distance between the PAI1 and EPO genes is only 3 cM.  相似文献   
100.
Cutaneous T cell lymphoma: characterization by monoclonal antibodies   总被引:10,自引:0,他引:10  
Kung  PC; Berger  CL; Goldstein  G; LoGerfo  P; Edelson  RL 《Blood》1981,57(2):261-266
Monoclonal antibodies to human T cells permit the characterization of the surface phenotype of cutaneous T cell lymphoma (CTCL). The majority of CTCL cells are reactive with OKT1 and OKT3 monoclonals, which identify peripheral T cells and mature thymocytes. The neoplastic cells also react with OKT4, which recognizes the inducer T cell subset; they are, however, unreactive with OKT5 monoclonal, which identifies cytotoxic/suppressor T cell subsets. These data are in agreement with previous functional studies demonstrating that CTCL is a neoplasm of inducer (helper) T cells.  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