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   625篇
  免费   22篇
  国内免费   1篇
耳鼻咽喉   17篇
儿科学   15篇
妇产科学   24篇
基础医学   94篇
口腔科学   9篇
临床医学   40篇
内科学   131篇
皮肤病学   21篇
神经病学   85篇
特种医学   19篇
外科学   41篇
综合类   3篇
预防医学   28篇
眼科学   9篇
药学   43篇
肿瘤学   69篇
  2024年   1篇
  2023年   10篇
  2022年   7篇
  2021年   22篇
  2020年   23篇
  2019年   22篇
  2018年   20篇
  2017年   11篇
  2016年   23篇
  2015年   20篇
  2014年   32篇
  2013年   33篇
  2012年   56篇
  2011年   31篇
  2010年   21篇
  2009年   25篇
  2008年   32篇
  2007年   42篇
  2006年   46篇
  2005年   40篇
  2004年   39篇
  2003年   27篇
  2002年   17篇
  2001年   3篇
  2000年   1篇
  1999年   3篇
  1998年   2篇
  1997年   3篇
  1996年   10篇
  1995年   4篇
  1994年   5篇
  1993年   3篇
  1992年   2篇
  1991年   3篇
  1989年   1篇
  1988年   2篇
  1986年   1篇
  1985年   1篇
  1982年   2篇
  1978年   1篇
  1976年   1篇
排序方式: 共有648条查询结果,搜索用时 62 毫秒
1.
2.
Pancreatic metastasis of malignant melanoma is rarely diagnosed while the patient is alive. We report a case of metastatic melanoma of the pancreas in a 35-year-old woman presenting with a solid mass of the pancreas. Her past medical history included a radical hysterectomy 2 years previously for malignant melanoma of the vagina. Twelve months later, lung metastasis was also resected. EUS-guided fine needle aspiration (EUS-FNA) identified that the pancreatic tumor was histologically and immunohistochemically identical to the surgical specimen of her lung neoplasm. Imaging studies including US, CT, and MRI have limited value to distinguish the tumors from primary ductal adenocarcinoma. EUS-FNA can provide tissue diagnosis from pancreatic masses, specifically when other modalities have failed.  相似文献   
3.
4.
To determine the levels of maturation and differentiation ofmurine CD4 single-positive (SP) T cells, we compared the secondaryresponses of staphylococcal enterotoxin A (SEA)-induced neonatalthymic, adult thymic and adult splenic CD4 SP T cell blastsprepared from whole or heat-stable antigenlow CD4 SP T cells.Proliferative responses upon re-stimulation with SEA were strongin adult splenic CD4 SP T cell blasts, but quite weak in neonatalthymic and adult thymic CD4 SP T cell blasts. SEA-induced IL-2production was weaker in neonatal thymic blasts than in theadult splenic CD4 SP T cell blasts. In contrast, SEA-inducedIL-4 production was high in neonatal thymic CD4 SP T cell blasts,and low in adult splenic and thymic CD4 SP T cell blasts. Expressionof GATA-3, that directs production of IL-4 in T cells, examinedat protein and mRNA levels, was higher in neonatal thymic cellsthan in adult thymic and splenic cells. These results suggestthat neonatal and adult thymic CD4 SP T cells in the final stageof maturation are relatively immature compared with adult splenicCD4 SP T cells. The cytokine production profile of neonatalthymic CD4 SP T cells suggests that they are inclined towardsa Th2 response.  相似文献   
5.
Heparinization is believed to be one of the methods to suppress thrombus formation on blood-contacting surfaces. However, this study hypothesizes that heparinization alone might not be sufficient to provide a blood-compatible surface; that is, a surface property that resists biofouling is necessary to obtain an effective heparin-modified surface. 2-Methacryloyloxyethyl phosphorylcholine (MPC) polymers with 2-aminoethyl methacrylate (AEMA) were synthesized to immobilize heparin through ionic bonding. The primary amino groups of AEMA were considered to be the polymer surface because the zeta-potential of the surface was positive when the mole fraction of the AEMA units was above 0.2. The antithrombogenic character of the polymer surface modified with heparin was evaluated by both Lee-White and microsphere column methods. The coagulation period of human whole blood in the absence of anticoagulant in glass tubing coated with the MPC polymer was longer than that in the original glass tube. Cell adhesion was completely inhibited on the MPC polymer surface after contact with human whole blood without anticoagulant. However, many adherent blood cells were observed on poly(2-ethylhexyl methacrylate-co-AEMA) (no MPC unit) even after heparinization. These results strongly indicate that the MPC polymer is a useful substrate where the heparin works well and that the heparin-immobilized MPC polymer has superior blood compatibility to the simple MPC polymer.  相似文献   
6.
Sequential treatment with lamivudine and interferon (IFN) has induced sustained biochemical and virologic responses in the majority of patients with chronic hepatitis B in France. However, the efficacy of sequential treatment in patients with chronic hepatitis B virus (HBV) genotype C infection has not been evaluated. Twenty-four HBe antigen-positive patients were treated with 100 mg lamivudine alone for 16-32 weeks, then with both 6 MU IFN-beta and lamivudine for 4 weeks, and lastly with IFN-beta alone for 20 weeks. Sustained response was achieved in 7 (29%) patients 24 weeks after the end of therapy. No lamivudine-resistant variants emerged in any patient. Hepatitis flare occurred in 3 patients after the withdrawal of lamivudine, but none had decompensation. The patients with sustained response were significantly younger at baseline (p = 0.033) and had a significantly lower HBV DNA level at the start of IFN (p = 0.020) than those without sustained response. In conclusion, the rate of response to sequential therapy with lamivudine and IFN in HBe antigen-positive patients with HBV genotype C infection was lower than the rate reported previously. Patients who were young or who had a favorable virologic response to lamivudine were more likely to have a sustained response.  相似文献   
7.
Although there are at least 13 interferon-alpha (IFN-alpha) subtypes in humans, interactions between the subtypes remain unknown. To understand IFN-alpha interactions, we examined the antiproliferative activities and the receptor binding affinities of different combinations of IFN-alpha2 and IFN-alpha8 using six renal cell carcinoma (RCC) cell lines. Although IFN-alpha8 was the more potent subtype, synergistic and antagonistic antiproliferative effects were also observed in certain combinations of IFN-alpha2 and IFN-alpha8. To analyze the interactions between IFN-alpha2 and IFN-alpha8, the receptor-binding kinetics of different combinations of IFN-alpha2 and IFN- alpha8 to the IFN-alpha receptors, IFNAR-1 or IFNAR-2, were measured using a surface plasmon resonance-based biosensor. Unexpectedly, the receptor binding kinetics to IFNAR-2 but not to IFNAR-1 were mutually related to antiproliferative activity and increase in the binding speed (K(a)) for IFNAR-2. Moreover, we observed the increased fluorescence intensity (FI) of biotin-labeled IFN-alpha8 to IFNAR-2 by receptor binding inhibition assay with unlabeled IFN-alpha2 but not the other combinations. These findings indicate that the binding manner of IFN-alpha8 for IFNAR-2 is different from that of IFN-alpha2, suggesting that binding of IFN-alpha8 rather than binding of IFN-alpha2 to IFNAR-2 leads to activation and subsequent antiproliferative activity despite the same antiviral activity in RCC.  相似文献   
8.
We herein report a case of pigmented condyloma acuminatum in the genital region. A histopathological examination revealed keratinocyte proliferation, papillomatosis and basal pigmentation. Cellular atypia was rarely observed. The patient also had ordinary skin‐colored nodules on the coronal sulcus. Polymerase chain reaction amplification with consensus primers for human papillomavirus (HPV) and subsequent sequencing confirmed an infection of HPV type 6. Pigmented condyloma acuminatum is not rare; however, making the differential diagnosis between bowenoid papulosis and seborrheic keratosis is sometimes difficult. The mechanism of pigmentation in such cases remains unknown and requires further investigation. HPV typing is a useful method for diagnosing the disease.  相似文献   
9.
This study examined the validity of extended-field-of-view (EFOV) ultrasound imaging for evaluating the quantity (cross-sectional area [CSA]) and quality (accumulation of intramuscular fat) of trunk skeletal muscles (rectus abdominis, abdominal oblique and erector spinae) using magnetic resonance imaging (MRI) as a reference. Thirty healthy young men participated in this study. Cross-sectional images of the trunk at the height of the third lumbar vertebra were acquired and compared by EFOV ultrasound imaging and MRI. No significant differences were observed in CSAs between the two methods (0.74 ≤ R2 ≤ 0.85). Echo intensities significantly correlated with MRI-derived accumulation of intramuscular fat in each skeletal muscle group. However, the correlation coefficients were relatively low (0.37 ≤ r ≤0.47; p < 0.05). These results indicate that EFOV ultrasound imaging is a reliable method for assessing trunk skeletal muscle CSA. Further research is warranted to find the optimal ultrasound setting for evaluating muscle quality.  相似文献   
10.
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