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   575篇
  免费   25篇
  国内免费   22篇
儿科学   34篇
妇产科学   3篇
基础医学   61篇
口腔科学   7篇
临床医学   69篇
内科学   105篇
皮肤病学   1篇
神经病学   7篇
特种医学   175篇
外科学   16篇
综合类   11篇
预防医学   85篇
眼科学   4篇
药学   29篇
肿瘤学   15篇
  2021年   2篇
  2020年   1篇
  2018年   3篇
  2017年   1篇
  2016年   2篇
  2015年   6篇
  2014年   9篇
  2013年   15篇
  2012年   4篇
  2011年   5篇
  2010年   17篇
  2009年   17篇
  2008年   5篇
  2007年   17篇
  2006年   7篇
  2005年   12篇
  2004年   6篇
  2003年   8篇
  2002年   6篇
  2001年   14篇
  2000年   7篇
  1999年   12篇
  1998年   30篇
  1997年   28篇
  1996年   41篇
  1995年   23篇
  1994年   19篇
  1993年   26篇
  1992年   14篇
  1991年   11篇
  1990年   21篇
  1989年   38篇
  1988年   30篇
  1987年   27篇
  1986年   17篇
  1985年   19篇
  1984年   11篇
  1983年   10篇
  1982年   20篇
  1981年   10篇
  1980年   10篇
  1979年   4篇
  1978年   2篇
  1977年   9篇
  1976年   18篇
  1975年   7篇
  1972年   1篇
排序方式: 共有622条查询结果,搜索用时 15 毫秒
131.
The objectives of the study were to determine regional changes in body composition, energy expenditure by means of doubly labeled water, and net energy balance during exposure to high and extreme altitudes (5,300-8,848 m). This study focuses on a subset of subjects who consumed the doubly labeled water (three base camp personnel and seven climbers). Regional body composition was determined by measuring skinfold thicknesses and circumferences at 10 different sites on the body. Energy expenditure was measured by doubly labeled water excretion. Discrepancies between actual energy expenditure and data obtained from diet records and body weight changes suggested a chronic underreporting of dietary energy intake, especially by those subjects who reached the highest altitudes. This underreporting may be due in part to diminished cognition or to a preferential focus on survival, rather than on filling out diet records accurately. Mean adjusted dietary intakes were 10.50 +/- 0. 65 MJ/d (2510 +/- 155 kcal/d) for those who remained at base camp, and 20.63 +/- 6.56 MJ/d (4931 +/- 1568 kcal/d) for those who climbed above base camp. Energy expenditure averaged 2.5-3.0 times sea level resting energy expenditure. Differential changes in regional body composition suggested a preferential loss of fat mass and a relative sparing of muscle mass, despite insufficient energy intake to maintain body weight.  相似文献   
132.
Bilateral peripheral pulmonary infiltrates caused by Pneumocystis carinii developed in a patient undergoing mediastinal irradiation after chemotherapy for Hodgkin disease. The paramediastinal part of the lung included within the treatment port remained clear during the 2 1/2 weeks of radiation therapy. The distribution of the pneumocystis infiltrates was altered by the radiation, producing a pattern that is the "radiographic negative" of typical post-radiation therapy paramediastinal fibrosis.  相似文献   
133.
The choice of a contrast agent for pulmonary angiography has important implications for patient comfort, image quality, and perhaps the safety of the procedure, particularly for "high-risk" patients. In a prospective study the nonionic, low-osmolality agent iopamidol eliminated the problem of image degradation due to coughing, and patients showed excellent tolerance for it. However, pressure measurements obtained within 3-5 minutes of injection of iopamidol and diatrizoate sodium meglumine 76% showed no significant difference in the hemodynamic effects of the two contrast agents, either for normotensive or for pulmonary hypertensive patients. Contrary to a common presumption, pulmonary hypertension by itself did not appear to increase the risk of pulmonary angiography. The theoretic presumption of greater hemodynamic stability with low-osmolality contrast agents was not clinically evident in this trial with iopamidol. At present, enhanced patient comfort and improved image quality remain the only confirmed bases for choosing this contrast agent for pulmonary angiography.  相似文献   
134.
Laparoscopy, minimally invasive and minimal access surgery with more surgeons performing these ad-vanced procedures. We highlight in the review several key emerging technologies such as the telementor-ing and virtual reality simulators, that provide a solid ground for delivering surgical education to rural area and allow young surgeons a safety net and confidence while operating on a newly learned technique.  相似文献   
135.
A retrospective cohort-study with a follow-up of 6-17 years was carried out in four general practices in the Netherlands in the period 1967-1983. In total 317 overweight men and 565 overweight women were followed in a continuous morbidity registration, starting in the year they were diagnosed as overweight (at age 20-50 years). Incidence of illnesses in this group was compared to that in a control group (444 men and 627 women not registered overweight), matched on sex, age and calendar-year at start of follow-up. The incidence of registered morbidity in the overweight group was higher for diabetes, gout, arteriosclerotic disease, arthrosis for men and women, and also for varicose veins for women. Increasing BMI at start of follow-up was associated with increased risk for most illnesses under study. For gout and arteriosclerotic disease in men, overweight appeared to be a risk factor at lower levels of BMI than in women.  相似文献   
136.
学术背景:成年人脑海马齿状回和嗅球等部位发现神经干细胞后,彻底改变了传统发生生物学所认为的成熟神经元一旦受损就不能再生这一观念,但神经干细胞存在取材不便、受伦理学限制及免疫排斥等缺陷。通过骨髓间充质干细胞移植治疗脑梗死,有望从组织结构功能上对坏死神经元进行修复。 目的:归纳总结近年来骨髓间充质干细胞移植治疗脑梗死方面的实验研究进展。检索策略:由该论文的研究人员应用计算机检索Pubmed数据库1998—01/2006—12的相关文献,检索词“mesenchymal stem cells,cerebralinfarction,cerebral ischemia,transplant”,并限定文章语言种类为English。同时计算机检索中国期刊全文数据库1998—01/2006—12的相关文献,检索词“骨髓间充质干细胞,脑梗死,脑缺血,移植”,并限定文章语言种类为中文。共检索到88篇文献,对资料进行初审,纳入标准:文章所述内容应与骨髓间充质干细胞移植治疗脑梗死、脑缺血的研究相关。排除标准:重复性研究。 文献评价:文献的来源主要是通过对骨髓间充质干细胞移植治疗脑梗死方面内容进行汇总分析。所选用的30篇文献中,1篇为综述,其余均为临床或基础实验研究。 资料综合:①骨髓间充质干细胞具有高度自我更新和多向分化潜能,在体内外可以分化为多种细胞,近年来作为组织工程的种子细胞用于脑梗死的治疗。②骨髓间充质干细胞来源方便,体外培养扩增快速,可通过静脉、动脉、立体定位注射和腹腔注射等途径移植人脑梗死模型动物体内,并且能够迁移至受损脑组织。③骨髓间充质干细胞可能通过分泌神经营养因子,减少神经细胞凋亡,替代受损神经元,促进血管、轴突、髓鞘等再生,激活内源性神经干细胞的增殖分化等机制修复受损脑组织。④骨髓间充质干细胞可作为基因载体,通过导人外源性基因,与基因治疗相结合治疗脑梗死效果更好。 结论:骨髓间充质干细胞作为种子细胞在治疗模型动物脑梗死方面已经取得一定效果,其详细机制仍有待进一步深入研究,而且在应用于临床前仍有许多理论和技术问题需要解决。  相似文献   
137.

Introduction

Recombinant human activated protein C (rhAPC) is the first drug for which a reduction of mortality in severe sepsis has been demonstrated. However, the mechanism by which this reduction in mortality is achieved is still not clearly defined. The aim of the present study was to evaluate the dynamics of the anticoagulant, anti-inflammatory and pro-fibrinolytic action of rhAPC in patients with severe sepsis, by comparing rhAPC-treated patients with case controls.

Methods

In this prospectively designed multicenter case control study, 12 patients who were participating in the ENHANCE study, an open-label study of rhAPC in severe sepsis, were treated intravenously with rhAPC at a constant rate of 24 μg/kg/h for a total of 96 h. Twelve controls with severe sepsis matching the inclusion criteria received standard therapy. The treatment was started within 48 h after the onset of organ failure. Blood samples were taken before the start of the infusion and at 4, 8, 24, 48, 96 and 168 h, for determination of parameters of coagulation and inflammation.

Results

Sepsis-induced thrombin generation as measured by thrombin-antithrombin complexes and prothrombin fragment F1+2, was reset by rhAPC within the first 8 h of infusion. The administration of rhAPC did not influence parameters of fibrinolysis and inflammation. There was no difference in outcome or occurrence of serious adverse events between the treatment group and the control group.

Conclusion

Sepsis-induced thrombin generation in severely septic patients is reset by rhAPC within the first 8 h of infusion without influencing parameters of fibrinolysis and inflammation.  相似文献   
138.
目的:建立肠系膜微淋巴管内皮细胞的培养技术,观察不同体积分数的休克淋巴液对大鼠肠系膜微淋巴管内皮细胞形态的影响。方法:实验于2004-02/07在河北北方学院病理生理学教研室及实验中心细胞培养室完成。选择健康雄性Wistar大鼠,体质量分别为220~300g和50~80g。实验方法:①无菌条件下制备大鼠重症失血性休克模型,引流肠系膜淋巴液或收集门静脉血;同时另取大鼠,引流正常淋巴液或正常门静脉血。②从动物种类、培养基、植块方法、胎牛血清浓度等方面对植块培养法进行改良,进行肠系膜微淋巴管内皮细胞原代培养并传代。实验分组:分为6组:胎牛血清组:培养液为DMEM 体积分数为0.1的胎牛血清;正常淋巴液组:培养液为DMEM 正常淋巴液;休克淋巴液组:培养液为DMEM 体积分数为0.04,0.06,0.08,0.10的休克淋巴液;正常血浆组:培养液为DMEM 正常血浆;休克血浆组:培养液为DMEM 休克血浆;无血清对照组:培养液为DMEM。实验评估:①光镜下观察大鼠肠系膜微淋巴管内皮细胞原代培养及传代情况。②光镜、扫描电镜及透射电镜下观察不同体积分数的休克淋巴液及不同作用时间(4,8,12h)对肠系膜微淋巴管内皮细胞形态及超微结构的影响。结果:①光镜下肠系膜微淋巴管内皮细胞原代培养及传代情况:内皮细胞呈扁平的梭形或多边形,大小均匀,胞核清晰,呈卵圆形。细胞生长融合形成单层后,呈典型的鹅卵石或铺路石样镶嵌状排列生长。②光镜下在休克淋巴液中肠系膜微淋巴管内皮细胞形态:体积分数为0.04的休克淋巴液作用4h时细胞逐渐收缩、变圆直至脱落漂浮,随着休克淋巴液体积分数增加及作用时间延长,细胞损伤逐渐加重,体积分数为0.08的休克淋巴液作用4h时核旁出现空泡,体积分数为0.10的休克淋巴液作用12h时细胞裂解成碎片。其他各组作用12h肠系膜微淋巴管内皮细胞形态无显著改变。③扫描电镜下在休克淋巴液中肠系膜微淋巴管内皮细胞形态:体积分数为0.04的休克淋巴液作用4h部分细胞逐渐收缩离壁,细胞间隙增大、细胞边缘的突起拉长、缩短、断裂,作用8,12h可见凋亡小体。其他各组作用12h肠系膜微淋巴管内皮细胞形态无显著改变。④透射电镜下在休克淋巴液中肠系膜微淋巴管内皮细胞形态:体积分数为0.04的休克淋巴液作用4h细胞膜形态不规整,胞浆内质网等膜性细胞器扩张,核形态不规则,作用8h线粒体呈球形扩张,细胞核逐渐出现固缩、似细胞凋亡改变,核周腔变宽;体积分数为0.08的休克淋巴液作用时间8h细胞内出现囊泡,内质网不同程度扩张,线粒体主要表现为浓缩、深染等改变,细胞膜边界不清,出现起泡、破碎等现象。其他各组作用12h肠系膜微淋巴管内皮细胞形态无显著改变。结论:成功建立了肠系膜微淋巴管内皮细胞的培养技术;休克淋巴液可导致肠系膜微淋巴管内皮细胞形态及超微结构损伤。  相似文献   
139.
To study red cell transfusion practice in 3216 coronary artery bypass graft (CABG) cases in 11 hospitals in 1988, abstracted patient records were stratified by diagnosis related group (DRG) (that is, DRG 106, coronary artery bypass without catheterization, or DRG 107, coronary artery bypass with catheterization) and International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) surgical procedure code. Means of units per transfused patient, age and length of stay, and in-hospital mortality rates were significantly greater for patients in DRG 106 than DRG 107. Gender was a significant factor for transfusion outcomes; female patients were more likely to undergo transfusion, and, when transfused, they received more units of red cells than male patients. For a given DRG/ICD-9-CM surgical procedure class, significant differences were found between hospitals in the percentage of patients transfused, but not in mean units of red cells per transfused patient. However, within individual hospitals, the proportion of patients transfused and the number of units per transfused patient did not vary significantly across DRG/ICD-9-CM procedure classes. These results suggest that circumstances operating within a hospital, still to be identified, had more influence on transfusion decisions than the nature of the surgical intervention.  相似文献   
140.
Preclinical studies of recombinant human interleukin-3 (rhIL-3) and granulocyte-macrophage colony-stimulating factor (rhGM-CSF) have shown enhancement of multilineage hematopoiesis when administered sequentially. This study was designed to evaluate the safety, tolerability, and biologic effects of sequential administration of rhIL- 3 and rhGM-CSF after marrow ablative cytotoxic therapy and autologous bone marrow transplantation (ABMT) for patients with malignant lymphoma. Thirty-seven patients (20 patients with non-Hodgkin's lymphoma and 17 patients with Hodgkin's disease) received one of four different treatment regimens before ABMT. Patients were entered in one of four study groups to receive rhIL-3 (2.5 or 5.0 micrograms/kg/day) administered by subcutaneous injection for either 5 or 10 days starting 4 hours after the marrow infusion. Twenty-four hours after the last dose of rhIL-3, rhGM-CSF (250 micrograms/m2/d as a 2-hour intravenous infusion) administration was initiated. rhGM-CSF was administered daily until the absolute neutrophil count (ANC) was > or = 1,500/microL for 3 consecutive days or until day 27 posttransplant. The most frequent adverse events in the trial included nausea, fever, diarrhea, mucositis, vomiting, rash, edema, chills, abdominal pain, and tachycardia. Three patients were removed from the study because of chest, skeletal, and abdominal pain felt to be probably related to study drug. Four patients died during the study period because of complications unrelated to either rhIL-3 or rhGM-CSF. The median time to recovery of neutrophils (ANC > or = 500/microL) and platelets (platelet count > or = 20,000/microL) was 14 and 15 days, respectively. There were fewer days of platelet transfusions than seen in historical control groups using rhGM-CSF, rhG-CSF, or rhIL-3 alone. In addition, there were fewer days of red blood cell transfusions compared with historical controls using no cytokines or rhGM-CSF. These data indicate that the sequential administration of rhIL-3 and rhGM-CSF after ABMT is safe and generally well-tolerated and results in rapid recovery of multilineage hematopoiesis.  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