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   504篇
  免费   35篇
  国内免费   2篇
耳鼻咽喉   1篇
儿科学   19篇
妇产科学   5篇
基础医学   50篇
口腔科学   27篇
临床医学   61篇
内科学   81篇
皮肤病学   8篇
神经病学   40篇
特种医学   98篇
外科学   42篇
综合类   9篇
预防医学   37篇
眼科学   4篇
药学   17篇
中国医学   3篇
肿瘤学   39篇
  2021年   3篇
  2020年   4篇
  2019年   3篇
  2018年   9篇
  2017年   3篇
  2016年   4篇
  2015年   12篇
  2014年   9篇
  2013年   15篇
  2012年   21篇
  2011年   16篇
  2010年   21篇
  2009年   25篇
  2008年   24篇
  2007年   20篇
  2006年   19篇
  2005年   19篇
  2004年   17篇
  2003年   17篇
  2002年   10篇
  2001年   7篇
  2000年   9篇
  1999年   12篇
  1998年   20篇
  1997年   18篇
  1996年   20篇
  1995年   14篇
  1994年   10篇
  1993年   11篇
  1992年   6篇
  1991年   5篇
  1990年   4篇
  1989年   13篇
  1988年   11篇
  1987年   7篇
  1986年   10篇
  1985年   5篇
  1984年   6篇
  1983年   8篇
  1982年   7篇
  1981年   10篇
  1980年   7篇
  1979年   4篇
  1978年   4篇
  1977年   7篇
  1976年   6篇
  1975年   4篇
  1974年   3篇
  1965年   2篇
  1922年   4篇
排序方式: 共有541条查询结果,搜索用时 15 毫秒
71.
Between June 1989 and June 1992, 144 patients participated in sequential clinical trials using peripheral blood progenitor cells (PBC) as their sole source of hematopoietic rescue following high-dose chemotherapy. All patients had received prior extensive combination chemotherapy and had marrow defects that precluded autologous bone marrow transplantation (ABMT). PBC were collected according to a single apheresis protocol. The initial 86 patients (group 1) had PBC collected without mobilization. Beginning in April 1991, PBC were mobilized solely with recombinant human granulocyte-macrophage colony-stimulating factor (rHuGM-CSF). Thirty-four patients (group 2) received rHuGM-CSF at a dose of 125 micrograms/m2/d by continuous intravenous infusion, and 24 patients (group 3) received rHuGM-CSF at a dose of 250 micrograms/m2/d by continuous intravenous infusion. Patients underwent at least six aphereses and had a minimum of 6.5 x 10(8) mononuclear cells (MNC)/kg collected. Cytokines were not routinely administered immediately after transplantation. A median of nine aphereses were required to collect PBC in group 1 and seven aphereses for groups 2 and 3 (P = .03). The time required to recover 0.5 x 10(9)/L granulocytes after transplant was significantly shorter (P = .0004) for the mobilized groups; the median time to recovery was 26 days for group 1, 23 days for group 2, and 18 days for group 3. Transplantation of PBC mobilized with rHuGM-CSF resulted in a shorter time to platelet (P = .04) and red blood cell (P = .01) transfusion independence. Mobilization with rHuGM-CSF alone resulted in efficient collection of PBC, that provided rapid and sustained restoration of hematopoietic function following high-dose chemotherapy. Mobilization of PBC with rHuGM-CSF alone is an effective method for patients who have received prior chemotherapy and have bone marrow abnormalities.  相似文献   
72.
Barrett’s oesophagus(BO)is a usually indolent condition that occasionally requires endoscopic therapy.Radiofrequency ablation(RFA)is an effective endoscopic treatment for high grade dysplasia(HGD)and intramucosal cancer in BO.It has a good efficacy,durability and safety profile although complications can occur.Here we describe a case of RFA in a patient with high grade dysplasia.Although the response to treatment was initially very good with the development of neosquamous epithelium,the patient very rapidly developed a squamous cell cancer of the oesophagus confirmed on radiology,histology and immunohistochemistry.Sanger sequencing confirmed that the original HGD and the squamous cell cancer(SCC)were derived from separate clonal origins.The report highlights the fact that SCC of the oesophagus has been noted after endoscopic ablation for BO previously and suggest that ablation of BO may encourage the clonal expansion of cells carrying carcinogenic mutations once a dominant clonal population has been eradicated.  相似文献   
73.
Look  AT; Peiper  SC; Douglass  EC; Trent  JM; Sherr  CJ 《Blood》1986,67(3):637-645
Spontaneous amplification of genes encoding two different human myeloid surface antigens was observed after DNA-mediated gene transfer of cellular DNA from the human myeloid cell line HL-60 into NIH-3T3 mouse fibroblasts. Transformed recipient cells with highly amplified expression of either of two donor membrane polypeptides, gp150 or p67, were isolated with a fluorescence-activated cell sorter (FACS), using monoclonal antibodies specific for human myeloid cells. Immunoprecipitation of enzymatically radioiodinated polypeptides from the surface of transformed NIH-3T3 cells confirmed that expression of these proteins was amplified tenfold to 20-fold in comparison to their expression on human myeloid cell lines. The cellular DNA of cloned secondary and tertiary transformants expressing high levels of gp150 and p67 contained amplified sets of DNA restriction fragments that hybridized with human repetitive DNA sequences. Cytogenetic analysis of subclones overexpressing gp150 revealed extrachromosomal double minutes (DMs), whose presence correlated with the unstable expression of the membrane polypeptide. Human sequences in gp150-positive clones did not localize to chromosomes, consistent with their association with extrachromosomal DMs. By contrast, p67-positive subclones stably expressed the antigen, and in situ hybridization to metaphase spreads demonstrated that amplified human DNA sequences were integrated into a specific marker chromosome. Cytogenetic analysis of the parental NIH- 3T3 subclone used in these studies disclosed DMs in a low percentage of metaphases, suggesting that the recipient cells have a propensity for amplifying donor DNA.  相似文献   
74.
Jaffe  HS; Cadman  EC; Farber  LR; Bertino  JR 《Blood》1986,68(2):562-564
Pretreatment hematocrit in 117 advanced-stage Hodgkin's disease patients treated with a combined modality therapy program was evaluated as an independent prognostic variable with regard to survival and relapse-free survival. Age greater than 40 years, and multiple extranodal sites of involvement were found to be statistically significant independent negative prognostic factors with regard to survival. Pretreatment hematocrit, however, was not an independent negative prognostic variable.  相似文献   
75.
The bacterial pathogen Vibrio parahaemolyticus utilizes a type III secretion system to cause death of host cells within hours of infection. We report that cell death is completely independent of apoptosis and occurs by a mechanism in which injection of multiple type III effectors causes induction of autophagy, cell rounding, and the subsequent release of cellular contents. Autophagy is detected by the appearance of lipidated light chain 3 (LC3) and by increases in punctae and vacuole formation. Electron microscopy reveals the production of early autophagic vesicles during infection. Consistent with phosphoinositide 3 (PI3) kinase playing a role in autophagy, treatment of infected cells with a PI3 kinase inhibitor attenuates autophagy in infected cells. Because many effectors are injected during a V. parahaemolyticus infection, it is not surprising that the presence of a sole PI3 kinase inhibitor does not prevent inevitable host-cell death. Our studies reveal an infection paradigm whereby an extracellular pathogen uses its type III secretion system to cause at least three parallel events that eventually result in the proinflammatory death of an infected host cell.  相似文献   
76.
Management of small‐bowel fistulas which are in an open abdomen and have no soft tissue overlay or a fistula tract involves many complications and challenges. Controlling the local leakage of enteric contents has a central role in the success of medical treatment. There are several methods to deal with fistula discharge but unfortunately, the technical solutions only partially address such problems and a definitive management of fistula discharge still remains an insoluble challenge. We describe a simple and cheap method to control fistula leakage by using a percutaneous endoscopic gastrostomy tube.  相似文献   
77.
78.
79.
Catheter-cooled (CC) interstitial ultrasound applicators were evaluated for their use in high-temperature coagulative thermal therapy of tissue. Studies in ex vivo beef muscle were conducted to determine the influences of applied electrical power levels (5-20 W per element), catheter flow rate (20-60 ml min(-1)), circulating water temperature (7-40 degrees C), and frequency (7-9 MHz) on temperature distribution and thermal lesion geometry. The feasibility of using multiple interstitial applicators to thermally coagulate a predetermined volume of tissue was also investigated. Results of these studies revealed that the directional shape of the thermal lesions is maintained with increasing time and power. Radial depths of the thermal lesions ranged from 10.7 +/- 0.7 mm after heating for 4 min with an applied power level of 5 W, to 16.2 +/- 1.4 mm with 20 W. The axial length of the thermal lesions is controlled tightly by the number of active transducers. A catheter flow rate of 20 to 40 ml min(-1) (52.2 +/- 5.5 kPa at 40 ml min(-1)) with 22 degrees C water was determined to provide sufficient cooling of the transducers for power levels used in this study. In vivo temperatures measured in the center of a 3-cm-diam peripheral implant of four applicators in pig thigh muscle reached 89.3 degrees C after 4 min of heating, with boundaries of coagulation clearly defined by applicator position and directivity. Conformability of heating in a clinically relevant model was demonstrated by inserting two directional CC applicators with a 2 cm separation within an in vivo canine prostate, and generating a thermal lesion measuring 3.8 cm x 2.2 cm in cross section while directing energy away from, and protecting the rectum. Maximum measured temperatures at midgland exceeded 90 degrees C within 20 min of heating. The results of this study demonstrate the utility of single or multiple CC applicators for conformal thermal coagulation and high temperature thermal therapy, with potential for clinical applications in sites such as prostate, liver, breast, or uterus.  相似文献   
80.
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