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   674篇
  免费   41篇
  国内免费   46篇
耳鼻咽喉   2篇
儿科学   47篇
妇产科学   20篇
基础医学   93篇
口腔科学   38篇
临床医学   95篇
内科学   165篇
皮肤病学   10篇
神经病学   23篇
特种医学   115篇
外科学   24篇
综合类   10篇
预防医学   33篇
眼科学   5篇
药学   52篇
  1篇
肿瘤学   28篇
  2023年   7篇
  2022年   5篇
  2021年   6篇
  2020年   2篇
  2019年   7篇
  2018年   10篇
  2017年   10篇
  2016年   15篇
  2015年   15篇
  2014年   21篇
  2013年   27篇
  2012年   12篇
  2011年   16篇
  2010年   22篇
  2009年   22篇
  2008年   13篇
  2007年   43篇
  2006年   19篇
  2005年   14篇
  2004年   6篇
  2003年   8篇
  2002年   10篇
  2001年   4篇
  2000年   9篇
  1999年   11篇
  1998年   45篇
  1997年   54篇
  1996年   54篇
  1995年   45篇
  1994年   30篇
  1993年   30篇
  1992年   2篇
  1991年   11篇
  1990年   7篇
  1989年   14篇
  1988年   24篇
  1987年   19篇
  1986年   14篇
  1985年   14篇
  1984年   6篇
  1983年   8篇
  1982年   9篇
  1981年   8篇
  1980年   11篇
  1978年   4篇
  1977年   8篇
  1976年   2篇
  1975年   4篇
  1967年   1篇
  1960年   1篇
排序方式: 共有761条查询结果,搜索用时 31 毫秒
31.
We describe a patient with angioimmunoblastic lymphadenopathy with dysproteinemia (AILD), who subsequently developed large-cell immunoblastic lymphoma of B-cell immunophenotype. At the time of the initial diagnosis, histologic examination of an inguinal lymph node showed typical features of AILD, and there was no evidence of a monoclonal B-cell population by immunohistochemical analysis. In situ hybridization and Southern blot analysis for Epstein-Barr virus (EBV) were negative. At autopsy 2 years later, the patient had widespread lymph node and organ involvement by large-cell immunoblastic lymphoma of B-cell immunophenotype. Southern blot analysis performed on DNA extracted from lymph nodes, liver, and spleen showed two patterns of Ig heavy chain and kappa light chain gene rearrangements. The T-cell receptor beta chain gene was in the germline configuration. Analysis with an EBV terminal repeat region probe showed two clonal populations that paralleled the Ig gene rearrangement studies. Double-labeling immunohistochemistry and in situ hybridization confirmed the presence of EBV within the neoplastic B cells. The data support the hypothesis that EBV was not etiologically related to AILD in this case, and that EBV proliferation may occur after the onset of the disease. Further, the data suggest that some B-cell lymphomas that arise in the setting of AILD resemble EBV-associated B-cell lymphomas that arise in other immunodeficiency states.  相似文献   
32.
Ley  K; Linnemann  G; Meinen  M; Stoolman  LM; Gaehtgens  P 《Blood》1993,81(1):177-185
Leukocyte rolling in venules is inhibited by several sulfated polysaccharides, by antibodies to the leukocyte adhesion receptor L- selectin (LECAM-1), and by recombinant soluble L-selectin. The sulfated fucose polymer fucoidin and the polyphosphomannan PPME bind to L- selectin and inhibit L-selectin-mediated lymphocyte adhesion to lymph node high endothelial venules (LN-HEV). We investigated whether fucoidin and PPME also inhibit leukocyte rolling. Rolling leukocyte flux was determined by intravital microscopy in 47 venules (diameter 21 to 50 microns) of the rat mesentery with and without micro-infusion of each reagent through 8-microns glass micropipettes. Micro-infusion (1 mg/mL) or intravenous (IV) injection (25 mg/kg) of fucoidin, but not vehicle, reduced leukocyte rolling by greater than 90%. The half- effective concentration was approximately 2.5 micrograms/mL. Stroboscopic fluorescence video microscopy showed that fucoidin decreased the fraction of rolling leukocytes from 44% of all leukocytes passing the venules in control to less than 1%. PPME micro-infusion (1 mg/mL) or IV injection (14 mg/kg) did not reduce leukocyte rolling. Hence, leukocyte rolling differs from lymphocyte homing with respect to the effect of PPME. This may be related to fucoidin binding to L- selectin with greater affinity than PPME. Alternatively, inflamed venular endothelium may express a ligand for L-selectin different from that constitutively expressed on LN-HEV.  相似文献   
33.
Charles Goodyear discovered the vulcanization process of natural rubber in the middle of the 19th century. In this paper, original ornaments produced by Charles Goodyear are investigated. Additionally, for comparison, a sample is produced according to Goodyear's patent (US 3633) as reference. Contrary to expectation, it is found that Charles Goodyear did not prepare the ornaments using the formulation of his patent, thus he excluded the white lead. Due to this, another reference sample is produced like the other but without white lead. It is proven that by artificial aging, natural rubber samples can get properties similar to the 150 years old rubber sample.

  相似文献   

34.
35.
36.
该文旨在介绍Beth Israel医疗中心采用大剂量术中放疗(HDR-IORT)治疗复发头颈癌的经验。对2001-2010年间头颈癌局部复发接受大剂量HDR-IORT的患者进行回顾分析。结果,76例患者的87个部位在肿瘤切除后接受了治疗。术后2年控制率为62%。平均总生存期为19个月,其中42%的患  相似文献   
37.
38.

Background

Treatment with selective vitamin D receptor activators such as paricalcitol have been shown to exert an anti-inflammatory effect in patients on hemodialysis, in addition to their action on mineral metabolism and independently of parathyroid hormone (PTH) levels. The objective of this study was to evaluate the additional antioxidant capacity of paricalcitol in a clinical setting.

Methods

The study included 19 patients with renal disease on hemodialysis, of whom peripheral blood was obtained for analysis at baseline and three months after starting intravenous paricalcitol treatment. The following oxidizing and inflammatory markers were quantified: malondialdehyde (MDA), nitrites and carbonyl groups, indoleamine 2,3-dioxygenase (IDO), tumor necrosis factor alfa (TNF-α), interleukin-6 (IL-6), interleukin-18 (IL-18) and C-reactive protein (CRP). Of the antioxidants and anti-inflammatory markers, superoxide dismutase (SOD), catalase, reduced glutathione (GSH), thioredoxin, and interleukin-10 (IL-10) levels were obtained.

Results

Baseline levels of oxidation markers MDA, nitric oxide and protein carbonyl groups significantly decreased after three months on paricalcitol treatment, while levels of GSH, thioredoxin, catalase and SOD activity significantly increased. After paricalcitol treatment, levels of the inflammatory markers CRP, TNF-α, IL-6 and IL-18 were significantly reduced in serum and the level of anti-inflammatory cytokine IL-10 was increased.

Conclusions

In renal patients undergoing hemodialysis, paricalcitol treatment significantly reduces oxidative stress and inflammation, two well known factors leading to cardiovascular damage.
  相似文献   
39.
BACKGROUND: Iron chelation therapy (ICT) with deferoxamine (DFO), the current standard for the treatment of iron overload in patients with transfusion-dependent disorders such as beta-thalassemia, requires regular subcutaneous or intravenous infusions. This can lead to reduced quality of life and poor adherence, resulting in increased morbidity and mortality in iron-overloaded patients with beta-thalassemia. Deferasirox is an orally administered iron chelator that has been approved for use in the United States, Switzerland, and other countries. OBJECTIVE: This analysis was conducted to compare patient-reported outcomes (PROs) during receipt of DFO infusions or once-daily oral therapy with deferasirox (ICL670). METHODS: PROs were prospectively evaluated as part of a randomized, Phase III study comparing the efficacy and safety profile of DFO 20 to 60 mg/kg per day with those of deferasirox 5 to 30 mg/kg per day in patients (age > or =2 years) with beta-thalassemia who were receiving regular transfusions and had a liver iron concentration of > or =2 mg/g dry weight. PRO questionnaires were completed by patients or a parent or legal guardian at baseline, week 4, week 24, and end of study (EOS). Patients assessed their level of satisfaction with study treatment (very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied) and rated its convenience (very convenient, convenient, neutral, inconvenient, or very inconvenient). Time lost from normal activities due to ICT in the previous 4 weeks was recorded using a single global assessment. At week 4, patients who had previous experience with DFO were asked to indicate their preference for treatment (ICT received before the study, ICT received during the study, no preference, or no response) and the reason for that preference. At EOS, all patients were asked if they would be willing to continue using the ICT they had received during the study. All study analyses were performed in all patients who received at least 1 dose of study medication. RESULTS: Five hundred eighty-six patients (304 females, 282 males; age range, 2-53 years) received treatment with DFO (n = 290) or deferasirox (n = 296). Significantly more patients treated with deferasirox reported being very satisfied or satisfied with treatment compared with those treated with DFO (week 4: 92.0% vs 50.4%, respectively; week 24: 89.6% vs 44.0%; EOS: 85.1% vs 38.7%; all, P < 0.001). At the same time points, the majority of those treated with deferasirox reported that treatment was very convenient or convenient compared with those treated with DFO (95.5% vs 21.3%, 91.7% vs 17.4%, and 92.7% vs 11.3%, respectively; all, P < 0.001). Among patients who had previously taken DFO and were randomized to receive deferasirox during the study, 96.9% reported a preference for deferasirox over DFO. At EOS, the proportion of patients indicating a willingness to continue study therapy was significantly greater in those receiving deferasirox than in those receiving DFO (85.8% vs 13.8%; P < 0.001). CONCLUSIONS: In this study, patient-reported satisfaction and convenience were significantly higher for the once-daily, oral ICT deferasirox than for DFO infusions. Among patients who had received DFO before the study, the majority indicated a preference for deferasirox over DFO. Most patients receiving deferasirox indicated that they would be willing to continue taking it. These results suggest that deferasirox had a positive impact on patients' daily lives.  相似文献   
40.
Even if neoplastic cells express tumor associated antigens they still may fail to function as antigen presenting cells (APC) if they lack expression of one or more molecules critical for the induction of productive immunity. These cellular defects can be repaired by physiologic activation, transfection, or fusion of tumor cells with professional APC. Although such defects can be repaired, antitumor specific T cells may still fail to respond in vivo if they may have been tolerized. Here, human pre-B cell acute lymphoblastic leukemia (pre-B ALL) was used as a model to determine if primary human tumor cells can function as alloantigen presenting cells (alloAPC) or alternatively whether they induce anergy. In the present report, we show that pre-B cell ALL express alloantigen and adhesion molecules but uniformly lack B7-1 (CD80) and only a subset express B7-2 (CD86). Pre-B ALL cells are inefficient or ineffective alloAPC and those cases that lack expression of B7-1 and B7-2 also induce alloantigen specific T- cell unresponsiveness. Under these circumstances, T-cell unresponsiveness could be prevented by physiologic activation of tumor cells via CD40, cross-linking CD28, or signaling through the common gamma chain of the interleukin-2 receptor on T cells. Taken together, these results suggest that pre-B ALL may be incapable of inducing clinically significant T-cell-mediated antileukemia responses. This defect may be not only due to their inability to function as APC, but also due to their potential to induce tolerance. Attempts to induce clinically significant antitumor immune responses may then require not only mechanisms to repair the antigen presenting capacity of the tumor cells, but also reversal of tolerance.  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