全文获取类型
收费全文 | 250篇 |
免费 | 6篇 |
国内免费 | 12篇 |
学科分类
医药卫生 | 268篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2016年 | 1篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 10篇 |
2007年 | 15篇 |
2006年 | 7篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 15篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有268条查询结果,搜索用时 31 毫秒
61.
Wittlinger T Voigtländer T Rohr M Meyer J Thelen M Kreitner KF Kalden P 《The international journal of cardiovascular imaging》2002,18(3):203-211
Non-invasive assessment of coronary arteries is possible with magnetic resonance imaging (MRI). Respiratory gated MR coronary angiography is a new imaging technique that permits reconstruction of the coronary arteries based on a three-dimensional (3D) data set obtained from the free-breathing patient. In this study, respiratory gated MR angiography (MRA) was performed to assess coronary artery occlusions. MRI was performed in 25 patients who had been referred for conventional coronary angiography because of suspected coronary artery disease. Coronary artery occlusion was evaluated in the proximal and middle vessel segments after multiplanar coronary reconstruction of the MR images. Five patients were excluded from the study; in the remaining 20 patients 120 coronary artery segments were analyzed. Good image quality could be obtained for 85% of the segments. Eighteen of the 24 occlusions were confirmed by MRI, the overall sensitivity was 75% and the specificity was 100%. The best results were found in the proximal left anterior descending (LAD) and descending parts of the right coronary artery (RCA), where all occlusions were confirmed. These results showed that coronary artery occlusions can be detected in the proximal and middle LAD and RCA using 3D respiratory gated MRA. Further technical improvements, especially in spatial resolution, are necessary before MRA can become a reliable diagnostic tool in the non-invasive evaluation of coronary arteries. 相似文献
62.
Activation of telomerase seems to be a prerequisite for immortalization and is found in permanent cell lines and most malignant tumors. Normal somatic cells are generally telomerase negative, except for bone marrow stem cells. Weak activity is also present in peripheral blood cells. In the present study strong telomerase activity was demonstrated in vivo in normal mature cells of the immune system, as well as in malignant lymphomas. Benign lymph nodes had lower telomerase activity than benign tonsils, which exhibited intermediate to high activity comparable with findings in malignant lymphomas. In benign tonsils the activity seemed to be restricted to germinal center B cells. In benign lymphoid tissues telomerase activity correlated with B-cell numbers and cell proliferation, but this was not observed in the lymphoma group. High- grade lymphomas exhibited higher levels of telomerase compared with low- grade cases. The data showed that in vivo activation of telomerase is a characteristic feature of germinal center B cells. Different signals for activation of telomerase are likely to exist, one of them being immune stimulation. The data suggest that telomerase activity in malignant lymphomas can be explained by an "induction and retention" model, ie, transformation occurs in a normal, mature B cell with reactivated telomerase, which is retained in the neoplastic clone. 相似文献
63.
Engraftment of marrow following autologous or allogeneic bone marrow transplantation (BMT) may be influenced by quantity and function of stem cells. T lymphocytes, supporting microenvironmental cells, and hematopoietic growth factors (HGF). To elucidate the physiologic role of interleukin-3 (IL-3) in the engraftment process, serum IL-3 levels were measured in over 400 samples from 77 transplant recipients before and for up to 3 weeks following transplantation using a novel enzyme- linked immunoabsorbent assay (ELISA) with a sensitivity of > or = 78 pg/mL. Thirty-seven patients received two to three log T-cell-depleted allografts. In the remaining 40 patients (18 autologous marrow, 12 allogeneic marrow, and 10 autologous peripheral blood [PB] stem cell), T cells were not depleted (non-TCD) from the grafts. A burst of IL-3 (peak levels, 1,500 to 6,000 pg/mL) was detected in the immediate posttransplant period between day 0 and day 14 in all non-TCD recipients and in 21 of 37 (57%) of TCD recipients. A strong inverse relationship between IL-3 levels and absolute neutrophil count (ANC) was observed in both non-TCD recipients (r = -.796) and in TCD recipients (r = -.897). However, both peak IL-3 levels and mean IL-3 levels from day 0 through 14 were significantly lower in TCD recipients compared with either autologous or unmodified allogeneic marrow recipients (P < .01). The lowest peak or mean day 0 through 14 IL-3 levels were observed in matched related recipients undergoing the most aggressive (2.5 to 3.0 log) T-cell-depleted BMT. Autografted patients receiving blood stem cell transplants alone or posttransplant granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony stimulating factor (GM-CSF) also had significantly lower peak IL- 3 levels (P < .01). In patients receiving TCD grafts, administration of antithymocyte globulin (ATG) posttransplant significantly increased peak IL-3 levels compared with patients not treated with ATG (P < .04). This study shows that endogenous release of IL-3 is strongly associated with myeloid engraftment and inversely related to ANC. Removal of T lymphocytes from donor marrow or acceleration of engraftment by use of stem cells or growth factors appears to blunt the endogenous release of IL-3 whereas use of ATG posttransplant increases IL-3 release. 相似文献
64.
A 43-year-old male with a phenotypically homogeneous, expanded subset of T cells presented in 1981 with anemia and neutropenia. The surface antigen phenotype of 99% of the peripheral blood lymphocytes was T3+, T8+, T4-, and they were morphologically large granular lymphocytes (LGL). The same cells comprised 37% of the marrow nucleated cells. Eight months after he presented, the peripheral blood T8+, LGL diminished spontaneously, and the anemia and neutropenia completely resolved. The patient remains hematologically normal as of October 1984. To determine if the T8+, LGL represented a clonal expansion, DNA from peripheral blood lymphocytes collected and cryopreserved when the patient was neutropenic and anemic, and when he was hematologically normal, was analyzed for clonal T-cell antigen receptor gene rearrangements. Using Southern blot analysis, a clonal DNA rearrangement was demonstrated, and this clone diminished but was still demonstrable in peripheral blood lymphocytes collected in 1984. The above observations implicate the expanded T8+, LGL in the pathogenesis of the neutropenia and anemia, yet the exact mechanism remains to be elucidated. 相似文献
65.
66.
Phyllodes tumours are rare breast neoplasms that present as painless breast masses. They are classified as benign, malignant and borderline. More rare presentations of these tumours include bilateral asynchronous disease and unilateral multifocal disease. Surgical excision with clear margins remains the treatment of choice for these tumours. The present case report is the first to be discussed in the literature. It describes a patient presenting with synchronous bilateral, multifocal breast phyllodes tumours who underwent immediate reconstruction with tissue expanders at the time of her mastectomies. 相似文献
67.
68.
Peter A Dargaville Beverley Copnell John F Mills Ismail Haron Jimmy KF Lee David G Tingay Jaafar Rohana Lindsay F Mildenhall Mei‐Jy Jeng Anushree Narayanan Malcolm R Battin Carl A Kuschel Joel L Sadowsky Harshad Patel Charles J Kilburn John B Carlin Colin J Morley 《Acta paediatrica (Oslo, Norway : 1992)》2013,102(2):e90-e93
69.
SE Gargosky KF Wilson PJ Fielder MA Vaccarello FB Diamond RC Baxter AL Rosenbloom J Guevara-Aguirre RG Rosenfeld 《Acta paediatrica (Oslo, Norway : 1992)》1994,83(S399):159-162
The molecular distribution of insulin-like growth factor I (IGF-I) and IGF-II among the IGF binding proteins (IGFBPs) was studied before and during IGF-I therapy in Ecuadorean adults with growth hormone receptor deficiency (GHRD). Of the total circulating IGF-I and IGF-II, 70% was carried by the 150 kDa complex in normal subjects, while in patients with GHRD, 50% of serum IGF-I, but only 30–35% of serum IGF-II, was measured within the 150 kDa IGFBP-3 region. Administration of IGF-I altered the concentration of IGF-I and IGF-II, although the percentage of total IGF measured within each IGFBP region was not affected, as the increase in IGF-I and the decrease in IGF-II were proportional. Similarly, serum concentrations of IGFBP-3 and the acid-labile subunit, measured by radioimmunoassay, were unaltered. Thus, administration of IGF-I to patients with GHRD was unable to correct the aberrant distribution of IGFs among the IGFBPs. 相似文献
70.
MRI of the pulmonary parenchyma 总被引:3,自引:0,他引:3
Imaging of the pulmonary parenchyma represents a unique challenge for MRI. Limited signal is caused by low proton density,
susceptibility artifacts, and physiological motion (cardiac pulsation, respiration). Recently, further improvements in MRI
techniques have widened the potential for investigations of pulmonary parenchymal disease. These include very short echo times,
ultrafast turbo-spin-echo acquisitions, projection reconstruction technique, breathhold imaging, ECG triggering, contrast
agents (perfusion imaging, aerosols), sodium imaging, hyperpolarized noble gas imaging, and oxygen enhancement. By using widely
available techniques, MRI is helpful in the assessment of (a) acute alveolitic processes in chronic infiltrative lung disease,
(b) detection and characterization of pulmonary nodules, (c) detection, characterization, and follow-up of pneumonia, (d)
differentiation of obstructive atelectasis from non-obstructive atelectasis and infarctions, and (e) measurements of lung
water content. Chronic bronchitis, bronchiectasis, and emphysema are not readily assessable by routine MRI techniques. More
sophisticated techniques are under investigation for MR imaging of pulmonary ventilation and perfusion. They represent the
beginning of functional MR imaging of the lung which will be established in the future. 相似文献