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   693篇
  免费   35篇
  国内免费   2篇
耳鼻咽喉   22篇
儿科学   45篇
妇产科学   10篇
基础医学   44篇
口腔科学   17篇
临床医学   73篇
内科学   166篇
皮肤病学   7篇
神经病学   47篇
特种医学   56篇
外科学   99篇
综合类   10篇
预防医学   36篇
眼科学   43篇
药学   23篇
肿瘤学   32篇
  2021年   9篇
  2020年   10篇
  2019年   10篇
  2018年   12篇
  2017年   14篇
  2016年   16篇
  2015年   16篇
  2014年   17篇
  2013年   28篇
  2012年   39篇
  2011年   40篇
  2010年   23篇
  2009年   25篇
  2008年   42篇
  2007年   37篇
  2006年   49篇
  2005年   39篇
  2004年   27篇
  2003年   21篇
  2002年   19篇
  2001年   8篇
  2000年   8篇
  1999年   18篇
  1998年   11篇
  1997年   10篇
  1996年   13篇
  1995年   8篇
  1994年   16篇
  1993年   10篇
  1992年   3篇
  1991年   3篇
  1990年   3篇
  1989年   6篇
  1988年   12篇
  1987年   7篇
  1986年   6篇
  1985年   13篇
  1984年   5篇
  1983年   9篇
  1982年   7篇
  1981年   8篇
  1980年   5篇
  1976年   6篇
  1972年   2篇
  1971年   5篇
  1969年   2篇
  1965年   3篇
  1963年   4篇
  1962年   2篇
  1956年   2篇
排序方式: 共有730条查询结果,搜索用时 15 毫秒
11.
OBJECTIVE: The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. MATERIALS AND METHODS: We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESD(TO)) (n = 23) and from the use of thermoluminescent dosimetry (ESD(TLD)) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESD(TO) by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESD(TO) and ESD(TLD) were correlated using linear regression analysis. RESULTS: The mean ESD(TO) for the chest and abdomen were 67 microGy and 65 microGy per procedure, respectively. The mean ESD(TLD) per radiograph was 70 microGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 microGy) per radiograph. Mean effective doses were 16 and 27 microSv per procedure for the chest and abdomen, respectively. ESD(TLD) was well correlated with ESD(TO) obtained from the total chest and abdomen radiographs for each infant (R(2) = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 x 10(-6) to 2 x 10(-6) and 0.6 x 10(-6) to 2.9 x 10(-6) for chest and abdomen radiographs, respectively. CONCLUSION: The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other.  相似文献   
12.
13.
Sixty-five multiply transfused patients with severe aplastic anemia were given cyclophosphamide followed by grafts anemia were given cyclophosphamide followed by grafts from HLA-identical siblings. The effect of the administration of viable donor buffy coat cells following the marrow inoculum was evaluated with regard to graft rejection and survival. Results in 43 patients so treated are presented along with those in 22 concurrent patients given marrow alone. Most patients given buffy coat had positive in vitro tests of sensitization indicating a high risk for graft rejection, while all but one of the patients given marrow alone had negative tests. Thirty of the 43 (70%) patients given marrow and buffy coat are alive between 10 and 61 mo (median 36) after grafting; 4 died after graft rejection and 6 with acute or chronic graft-versus-host disease (GVHD). Eleven of the 22 (50%) patients given marrow alone are alive between 29 and 65 mo (median 52); 7 died after graft rejection and 3 with GVHD. The addition of buffy coat cell infusions to the marrow inoculum reduced the risk of rejection and increased survival in the currently reported transfused patients when compared to patients grafted before 1976. However, there was an increased risk of chronic GVHD. Recipients of marrow from female donors survived slightly better (73%) than recipients of male marrow (58%).  相似文献   
14.
15.
16.
Abstract

Background: Tongue-related complications can be seen in suspension laryngoscopy (SL) procedures.

Aims/objectives: This study aimed to detect tongue edema associated with the pressure exerted by a rigid direct laryngoscope by measuring the tongue area using ultrasonography (USG) in patients undergoing SL procedures.

Material and methods: The study group included 31 patients and the control group consisted of 33 patients. Submental USG examinations of the tongue in the coronal plane were performed. In the study and control groups, the first examination (TA1) was done immediately after intubation and the second examination (TA2) was done after the surgery procedure but before extubation. The USG results regarding tongue area for both the groups were compared.

Results: The study and control groups significantly differed in terms of the postoperative tongue area measurements (TA2), as well as tongue edema (based on the TA2???TA1) values.

Conclusions and significance: Direct rigid laryngoscopes may cause tongue edema in SL procedures which was demonstrated by the USG. This tongue edema can be a result of ischemia–reperfusion injury in the tongue due to the pressure exerted by a direct rigid laryngoscope. This study is the first to demonstrate the possible role of USG examination in determining the side effects of SL procedures on the tongue.

Trial Registration ClinicalTrials.gov Identifier: NCT04205253  相似文献   
17.
18.
Epstein-Barr virus lymphoproliferation after bone marrow transplantation   总被引:16,自引:7,他引:16  
We review 15 cases of secondary B-cell lymphoproliferative disorders that occurred among 2,475 patients who received allogeneic bone marrow transplants (BMTs) at the Fred Hutchinson Cancer Research Center (Seattle) between 1969 and 1987. The histopathologic findings in 14 of the 15 patients spanned a wide spectrum of lymphoproliferative lesions. One patient had features characteristic of angioimmunoblastic lymphadenopathy. Epstein-Barr virus (EBV) genomic sequences were identified by Southern blot analysis in each of the 13 patients evaluated. Ten of the 12 lesions evaluated originated in donor cells. In two patients, who had mixed chimerism after transplantation, the lesions originated in host cells. The combined evidence from immunoglobulin light chain staining and the analysis of immunoglobulin heavy chain gene rearrangement indicated that the lesions in most patients represented polyclonal proliferations that gave rise to clonal subpopulations. The results indicate an overall actuarial incidence of 0.6% for this complication in BMT recipients. Anti-CD3 monoclonal antibody (MoAb) treatment of acute graft-v-host disease (GVHD) and T cell depletion of the donor marrow were statistically significant risk factors, and GVHD appeared to play a contributing role, particularly in the setting of human leukocyte antigen (HLA) disparity. Two patients had no identifiable risk factors. Prophylaxis or treatment with acyclovir had no detectable effect in the patients; all but two died with uncontrolled lymphoproliferation.  相似文献   
19.
Watermelon alpha-galactosidase (EC 3.2.1.22) was immobilized on a natural (chitin) and a synthetic anion-exchange (Amberlite IRA-938) support by covalent coupling methods. The procedure entails the activation of supports with 1,1'-carbonyldiimidazole (CDI), followed by immobilization of the enzyme on to these supports without and with a spacer arm; gamma-aminobutyric acid (GABA). Optimization of activation was performed by changing the CDI concentrations and coupling efficiencies. The comparison of two immobilization techniques for both chitin and Amberlite IRA-938 was made by comparing different enzyme concentrations against enzyme activity yield. Furthermore, the storage stability of the immobilized enzymes was also investigated and chitin immobilized alpha-galactosidase was found to be better. Although the activity yield of immobilized enzymes were the same for both supports, the short storage stability of immobilized enzyme on Amberlite IRA-938 is currently a drawback to its applications.  相似文献   
20.
BACKGROUND: Umbilical defects may cause technical problems for general surgeons in patients during laparoscopic cholecystectomy (LC) operations and may increase the incidence of incisional hernia. AIM: The objectives of this study were to determine the optimal repair method for umbilical hernias that already exist or are encountered incidentally and to present data regarding potential problems that may occur during LC. SETTINGS AND DESIGN: Medical records of patients who had received simultaneous umbilical hernia repair (UHR) with LC were investigated retrospectively. MATERIALS AND METHODS: Cholelithiasis was accompanied by umbilical hernia in 64 (8.6%) out of 745 patients who underwent LC and UHR simultaneously in our hospital between 2000 and 2004. STATISTICAL ANALYSIS USED: The Mann-Whitney U, Chi-square, One-Way Anova, Kaplan-Meier survival analysis, the log-rank test and t test were used for statistical analyses. RESULTS: LC was followed by UHR using primary suture (Group 1), Mayo repair (Group 2) and flat mesh-based repair (Group 3) in 32 (50%), 18 (28.1%) and 14 (21.9%) patients, respectively. Mean body mass indexes (BMI) of patients were 26.6 kg/m 2, 29.2 kg/m 2 and 39.9 kg/m 2 in Groups 1, 2 and 3, respectively. Recurrence rates were 9.4%, 5.6% and none (0%) in Groups 1, 2 and 3, respectively. Recurrence was observed in three (7.0%) out of 43(67.2%) patients with BMI > or = 30 kg/m 2 while umbilical hernia recurred in one (4.8%) out of 21 (32.8%) patients with BMI < 30 kg/m 2. Overall morbidity and mortality rates were 14.1% and 0%, respectively. CONCLUSIONS: The outcomes of the UHR with mesh after laparoscopic surgeries appear to be better for either obese or non-obese patients than primary suture techniques in recurrence rates.  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