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   456篇
  免费   34篇
  国内免费   105篇
耳鼻咽喉   1篇
儿科学   28篇
妇产科学   5篇
基础医学   49篇
口腔科学   32篇
临床医学   113篇
内科学   108篇
皮肤病学   6篇
神经病学   10篇
特种医学   69篇
外科学   32篇
综合类   37篇
预防医学   12篇
眼科学   5篇
药学   55篇
中国医学   1篇
肿瘤学   32篇
  2021年   5篇
  2019年   3篇
  2018年   5篇
  2017年   8篇
  2016年   7篇
  2015年   11篇
  2014年   6篇
  2013年   16篇
  2012年   7篇
  2011年   12篇
  2010年   18篇
  2009年   19篇
  2008年   7篇
  2007年   62篇
  2006年   14篇
  2005年   24篇
  2004年   12篇
  2003年   9篇
  2002年   12篇
  2001年   5篇
  2000年   12篇
  1999年   6篇
  1998年   45篇
  1997年   36篇
  1996年   38篇
  1995年   17篇
  1994年   24篇
  1993年   14篇
  1992年   11篇
  1991年   3篇
  1990年   12篇
  1989年   14篇
  1988年   14篇
  1987年   13篇
  1986年   12篇
  1985年   5篇
  1984年   3篇
  1982年   4篇
  1981年   5篇
  1980年   5篇
  1978年   4篇
  1977年   7篇
  1976年   6篇
  1975年   3篇
  1974年   2篇
  1973年   2篇
  1971年   3篇
  1970年   3篇
  1966年   2篇
  1965年   2篇
排序方式: 共有595条查询结果,搜索用时 15 毫秒
61.
BACKGROUND: Peripheral blood progenitor cells (PBPCs) are commonly collected and used to reconstitute hematopoiesis after high-dose chemotherapy. However, strategies for optimal collection and assessment of leukapheresis components are not standardized. STUDY DESIGN and METHODS: Hematopoietic progenitor cell assays were performed on 369 leukapheresis components collected from 95 patients who had received doxorubicin-based chemotherapy and/or granulocyte-colony-stimulating factor (G-CSF). Precollection patient hematologic values, leukapheresis collection values, component hematopoietic progenitor cell assays, and patient outcome measures were summarized. The kinetics of mononuclear cell (MNC) and PBPC mobilization were assessed among four patient groups. RESULTS: Patient group was a significant predictor of the peripheral blood MNC count on the day of collection (p<0.0001), and that value was a significant predictor of granulocyte-macrophage– colony-forming unit (CFU-GM) yield (p<0.0001). This relationship between the peripheral blood MNC count on the day of collection and CFU- GM yield differed according to patient group (p<0.0001). CFU-GM made up a larger fraction of peripheral blood MNCs collected from patients who received chemotherapy plus G-CSF than collected from those who received G-CSF alone. Moreover, the peripheral blood MNC count and the corresponding CFU-GM yield increased significantly on consecutive days of collection in patient groups receiving chemotherapy and G-CSF but were unchanged or decreased in patients receiving G-CSF alone. CONCLUSION: The relationship between peripheral blood MNC count and leukapheresis component CFU-GM yield differed significantly between patients who received chemotherapy and G-CSF and those who received G- CSF alone for the mobilization of PBPCs. Patient peripheral blood MNC count and component CFU-GM yield are useful for both assessing and suggesting revisions to PBPC mobilization and collection strategies.  相似文献   
62.
63.

Objective

While respiratory symptoms in the first year of life are relatively well described for term infants, data for preterm infants are scarce. We aimed to describe the burden of respiratory disease in a group of preterm infants with and without bronchopulmonary dysplasia (BPD) and to assess the association of respiratory symptoms with perinatal, genetic and environmental risk factors.

Methods

Single centre birth cohort study: prospective recording of perinatal risk factors and retrospective assessment of respiratory symptoms during the first year of life by standardised questionnaires. Main outcome measures: Cough and wheeze (common symptoms), re-hospitalisation and need for inhalation therapy (severe outcomes). Patients: 126 preterms (median gestational age 28.7 weeks; 78 with, 48 without BPD) hospitalised at the University Children''s Hospital of Bern, Switzerland 1999-2006.

Results

Cough occurred in 80%, wheeze in 44%, rehospitalisation in 25% and long term inhalation therapy in wheezers in 13% of the preterm infants. Using logistic regression, the main risk factor for common symptoms was frequent contact with other children. Severe outcomes were associated with maximal peak inspiratory pressure, arterial cord blood pH, APGAR and CRIB-Score.

Conclusions

Cough in preterm infants is as common as in term infants, whereas wheeze, inhalation therapy and re-hospitalisations occur more often. Severe outcomes are associated with perinatal risk factors. Preterm infants who did not qualify for BPD according to latest guidelines also showed a significant burden of respiratory disease in the first year of life.  相似文献   
64.
A growing body of evidence has demonstrated the prognostic significance of sarcopenia in surgical patients as an independent predictor of postoperative complications and outcomes. These included an increased risk of total complications, major complications, re-admissions, infections, severe infections, 30 d mortality, longer hospital stay and increased hospitalization expenditures. A program to enhance recovery after surgery was meant to address these complications; however, compliance to the program since its introduction has been less than ideal. Over the last decade, the concept of prehabilitation, or “pre-surgery rehabilitation”, has been discussed. The presurgical period represents a window of opportunity to boost and optimize the health of an individual, providing a compensatory “buffer” for the imminent reduction in physiological reserve post-surgery. Initial results have been promising. We review the literature to critically review the utility of prehabilitation, not just in the clinical realm, but also in the scientific realm, with a resource management point-of-view.  相似文献   
65.
Methods to reliably measure tissue oxygenation in situ are currently lacking. We have developed a vertically oriented, dorsal, bipedicle flap model that is easy to perform, reliably reproduces tissue ischemia, eliminates craniocaudal variation, and is amenable to studying therapeutic modalities. The effect of narrowing this flap on tissue oxygenation measured with Licox electrodes has previously been presented. In this study we utilize in situ EPR spectroscopy to demonstrate the oxygen gradient in the flap as a function of flap width and placement of a silicone sheet directly under the flap. The effect of wound healing over a 2 week period is demonstrated. Twenty four, 300 gm male Sprague‐Dawley rats underwent creation of the bipedicle flap according to the following groups: 2.5 cm flap with silicone, 2.0 cm flap without silicone, 2.0 cm flap with silicone. Each group of 6 animals was injected with EMS char at 2 cm intervals along the flap and one injection in the control, non‐ischemic tissue. A 4th group underwent 2.0 cm flaps with silicone and use of lithium phthalocyanin as the paramagnetic material. Wound measurements and EPR spectroscopy were performed on days 3, 7, 10 and 14. On day 14, after EPR measurements, the animals were sacrificed and their wounds excised. One flap and one control wound were preserved for histologic analysis, the other flap and control wounds were prepared for lactate measurements. EPR spectroscopy demonstrated a gradient of oxygen that was lowest in the center of the flap and greatest at either end. Changes in the oxygen gradient correlated with narrowing and placement of the intervening silicone sheet. This new technology has never been utilized in an animal model of impaired wound healing. Comparison of recently developed paramagnetic materials for optimal tissue oxygen and free radical measurements will be presented.  相似文献   
66.

Background  

Because of a high cardiovascular disease (CVD) risk in people with Familial Hypercholesterolemia (FH), early prevention of cardiovascular disease is important for health gain and cost reduction. This project focuses on the development and evaluation of an innovative intervention aiming to reduce CVD risk by promoting a healthy lifestyle among people with FH.  相似文献   
67.
目的分析2005年1月~2011年12月在北京医院维持性血液透析死亡患者的病例特点和死亡原因。方法回顾性的检出维持血液透析大于3个月的死亡患者共83例,计算本中心从2005年起每年维持透析患者的死亡人数和死亡率;将死亡患者根据年龄分为3组,60岁以下中年组,60~79岁老年组和80岁以上高龄组,分析3组的人口学资料、有无糖尿病、透析龄和死亡原因等。结果从2005年起,北京医院每年维持透析患者的死亡率依次为11.00%,10.90%,8.30%。8.10%,10.10%,8.70%和6.34%;83例死亡患者中,男性49例,女性34例,平均年龄71.812.0岁(42岁~94)岁,中年组(小于60岁)14例,老年组(60~79)岁46例,高龄组(大于80)岁23例;3组患者在性别上无统计学差异。透析龄在中年组最长,平均77.2±73.0月,高龄组为44.0±35.5月,老年组透析龄最短,平均为33.2±28.1月;3组之间的差异有统计学意义。老年组患者糖尿病肾病居多;死亡原因在各组有明显的差别,中年组50%死于脑血管疾病,脑出血居多;高龄组56.50%死于感染中毒性休克。老年组死亡原因较复杂,死亡率超过10%的依次为感染中毒性休克、心肌梗死或心力衰竭、肿瘤、营养不良-炎症-动脉粥样硬化综合征(Malnutrition-inflammation-atherosclerosissyndrome,MIAsyndrome)和猝死。结论北京医院单中心血液透析死亡患者绝大多数为老年患者。年龄不是决定透析预后不良的主要危险因素,糖尿病是影响预后的重要因素,不同年龄组患者死亡原因不同,中年患者脑血管疾病多见,高龄患者感染中毒性休克常见,老年患者的死亡原因多样化,包括心脑血管疾病、感染、肿瘤和MIA综合征。±  相似文献   
68.
AIM: To assess the prevalence and location of advanced neoplasia in patients undergoing colonoscopy, and to compare the yield per indication. METHODS: In a multicenter colonoscopy survey (n = 18 hospitals) in the Amsterdam area (Northern Holland), data of all colonoscopies performed during a three month period in 2005 were analyzed. The location and the histological features of all colonic neoplasia were recorded. The prevalence and the distribution of advanced colorectal neoplasia and differences in yield between indication clusters were evaluated. Advanced neoplasm was defined as adenoma 〉 10 mm in size, with 〉 25% villous features or with high-grade dysplasia or cancer. RESULTS: A total of 4623 eligible patients underwent a total colonoscopy. The prevalence of advanced neoplasia was 13%, with 281 (6%) adenocarcinomas and 342 (7%) advanced adenomas. Sixty-seven percent and 33% of advanced neoplasia were located in the distal and proximal colon, respectively. Of all patients with right-sided advanced neoplasia (n = 228), 51% had a normal distal colon, whereas 27% had a synchronous distal adenoma. Ten percent of all colonoscopies were performed in asymptomatic patients, 7% of whom had advanced neoplasia. In the respective procedure indication clusters, the prevalence of rightsided advanced neoplasia ranged from 11%-57%. CONCLUSION: One out of every 7-8 colonoscopies yielded an advanced colorectal neoplasm. Colonoscopy is warranted for the evaluation of both symptomatic and asymptomatic patients.  相似文献   
69.
Chlorpropamide-induced pure white cell aplasia   总被引:2,自引:0,他引:2  
Levitt  LJ 《Blood》1987,69(2):394-400
We investigated the mechanism for isolated agranulocytosis and marrow pure white cell aplasia in an elderly man receiving 0.5 to 1.0 g per day of chlorpropamide (Chl) without other toxic drug exposure or overt systemic illness. Patient marrow revealed an absence of recognizable granulocytic precursors; megakaryocytes and erythroid precursors were normal. The WBC count was 1800/mm3 on admission with only 2% neutrophils; the absolute neutrophil count first exceeded 500/mm3 on the 17th day following cessation of Chl. A serum Chl level on admission was 100 micrograms/mL (acute phase, AP); no Chl was detected in serum (convalescent phase, CP) assessed on the 22nd hospital day. Antineutrophil antibodies were not detected, and T cell depletion failed to augment patient in vitro granulopoiesis. Patient AP serum produced potent complement-mediated inhibition (87% +/- 7%) of autologous granulocyte progenitors (CFU-GM) with minimal inhibition of erythroid (11% +/- 5%) or multipotent (5% +/- 4%) progenitor cells. Selective inhibition by patient AP serum of CFU-GM (74% +/- 11%) was also seen against two allogeneic marrows. Patient CP serum no longer inhibited (6% +/- 4%) autologous CFU-GM. Addition of Chl (5 to 120 micrograms/mL) to CP serum but not to control serum resulted in potent drug concentration-dependent complement-mediated inhibition of autologous and allogeneic CFU-GM. Inhibition of CFU-GM in the presence of Chl was no longer demonstrable following immunoabsorbent removal of IgG from patient serum. Patient serum in the presence of Chl had limited activity against morphologically recognizable marrow granulocytic precursors in a microimmunofluorescence assay. These results are most consistent with the development of Chl-dependent, selective antibody-mediated immune inhibition of granulopoiesis.  相似文献   
70.

Objectives

The aim of the study was to determine whether behaviourally informed short message service (SMS) primer and reminder messages could increase the return rate of HIV self‐sampling kits ordered online.

Methods

The study was a 2 × 2 factorial design randomized control trial. A total of 9585 individuals who ordered a self‐sampling kit from www.freetesting.hiv different SMS combinations: 1) standard reminders sent days 3 and 7 after dispatch (control); 2) primer sent 1 day after dispatch plus standard reminders; 3) behavioural insights (BI) reminders (no primer); or 4) primer plus BI reminders. The analysis was restricted to individuals who received all messages (n = 8999). We used logistic regression to investigate independent effects of the primer and BI reminders and their interaction. We explored the impact of sociodemographic characteristics on kit return as a secondary analysis.

Results

Those who received the primer and BI reminders had a return rate 4% higher than that of those who received the standard messages. We found strong evidence of a positive effect of the BI reminders (odds ratio 1.13; 95% confidence interval 1.04–1.23; P = 0.003) but no evidence for an effect of the primer, or for an interaction between the two interventions. Odds of kit return increased with age, with those aged ≥ 65 years being almost 2.5 times more likely to return the kit than those aged 25–34 years. Men who have sex with men were 1.5–4.5 times more likely to return the kit compared with other sexual behaviour and gender identity groups. Non‐African black clients were 25% less likely to return the kit compared with other ethnicities.

Conclusions

Adding BI to reminder messages was successful in improving return rates at no additional cost.  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