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   562篇
  免费   37篇
  国内免费   16篇
耳鼻咽喉   8篇
儿科学   18篇
妇产科学   6篇
基础医学   49篇
口腔科学   7篇
临床医学   62篇
内科学   127篇
皮肤病学   10篇
神经病学   7篇
特种医学   78篇
外科学   147篇
综合类   11篇
预防医学   20篇
眼科学   2篇
药学   41篇
肿瘤学   22篇
  2020年   5篇
  2019年   3篇
  2018年   6篇
  2017年   8篇
  2016年   11篇
  2015年   9篇
  2014年   12篇
  2013年   12篇
  2012年   15篇
  2011年   17篇
  2010年   13篇
  2009年   11篇
  2008年   11篇
  2007年   24篇
  2006年   11篇
  2005年   22篇
  2004年   19篇
  2003年   15篇
  2002年   12篇
  2001年   14篇
  2000年   12篇
  1999年   10篇
  1998年   17篇
  1997年   23篇
  1996年   26篇
  1995年   23篇
  1994年   23篇
  1993年   16篇
  1992年   13篇
  1991年   18篇
  1990年   19篇
  1989年   27篇
  1988年   14篇
  1987年   14篇
  1986年   8篇
  1985年   8篇
  1984年   6篇
  1983年   5篇
  1982年   8篇
  1981年   6篇
  1979年   7篇
  1978年   6篇
  1977年   5篇
  1976年   5篇
  1975年   10篇
  1974年   3篇
  1973年   6篇
  1970年   3篇
  1968年   3篇
  1967年   3篇
排序方式: 共有615条查询结果,搜索用时 0 毫秒
51.
目的:通过对老年人进行血浆溶血磷脂酸和磷脂酸的筛检,从而认识血浆溶血磷脂酸和磷脂酸在血栓预防中的作用。方法:对2004-04/07期间的1657名和2005-04/07期间的1748名离休干部进行血浆溶血磷脂酸和磷脂酸含量测定,并对溶血磷脂酸>3.0μmol/L和磷脂酸>5.0μmol/L的阳性人员进行药物干预。同时,选择2004年溶血磷脂酸和/或磷脂酸阳性人员119人,随机分为两组:①干预组(n=72):男63人,女9人,平均年龄78岁。口服阿司匹林100mg/d,持续1个月。②对照组(n=47):男42人,女5人,平均年龄76岁。干预后,测定两组血浆中溶血磷脂酸和磷脂酸的含量。结果:纳入对象全部进入结果分析。2005年磷脂酸及血浆溶血磷脂酸 磷脂酸阳性率均明显低于2004年(P<0.01),尤其是磷脂酸的阳性率降低的更为明显。2005年血浆溶血磷脂酸和磷脂酸的平均值均明显低于2004年(P<0.01)。干预组干预后血浆溶血磷脂酸和磷脂酸明显低于干预前及对照组(P<0.01)。结论:①血浆溶血磷脂酸和磷脂酸的测定可作为血栓预警和了解抗血栓药物疗效的一种手段。②阿司匹林干预后,血浆溶血磷脂酸和磷脂酸的含量均降低,可作为一种降低缺血性疾病发生率的有效途径。  相似文献   
52.
The term "spontaneous gastric rupture" is used to describe our cases of neonatal gastric perforation. Nineteen such neonates are reviewed. Current opinions regarding the possible etiology is included in the discussion. Neonatal asphyxia was the most commonly seen predisposing cause in our series (63%). Roentgenograms of the abdomen are most helpful in making a positive diagnosis. Surgical repair is the treatment of choice. All the surviving patients in our series underwent surgical repair. The need for gastrostomy during surgery should be individualized. The mortality was 27% in the cases operated since 1970; a significant improvement as compared to a mortality rate of 62% for the cases operated before 1970.  相似文献   
53.
We report the first case in the world literature of a patient with an atrial septal defect, severe pulmonary hypertension, and equalization of pulmonary and systemic pressures, who underwent successful closure of an ASD following prolonged therapy with the intravenous vasodilator epoprostenol. Judicious use of continuous prostacyclin in apparently inoperable patients with congenital heart disease may be associated with significant reversal of pulmonary hypertension, and conversion to an operable state.  相似文献   
54.
INTRODUCTION: Previously, we reported an increase in interstitial collagen and total mast-cell numbers in heart failure versus normal myocardium. A secondary increase, primarily in chymase-negative mast cells, occurred following LVAD support compared to matched pre-LVAD tissue samples and was associated with a decrease in interstitial collagen and bFGF. To further elucidate the changes in interstitial collagen, we investigated the direct interaction between mast cells, isolated from failing myocardium with or without previous LVAD support, and human fibroblasts in a coculture model. Additionally, the expression of HSP-47, the pro-collagen-specific chaperone protein, was determined in the particular myocardium. MATERIALS AND METHODS: Myocardial tissue was obtained from 10 patients with end-stage dilated cardiomyopathy (DCM) at the time of transplantation. Five patients were transplanted following LVAD support, five patients without previous LVAD support. Mast cells were isolated according to a standard protocol, including collagenase digestion and cell separation. The isolated mast cells were co-cultured with human fibroblasts for 12 h, with or without stimulation of degranulation, and protein synthesis was measured by [(3)H]-proline incorporation. HSP-47 immunostaining was performed in the different myocardial samples and the positive cells were quantified. RESULTS: Stimulated mast cells isolated from DCM tissue (without previous LVAD support) caused a 92% increase in [(3)H]-proline incorporation and consequently in protein production in fibroblasts compared to mast-cell free culture (P < 0.01), while conversely stimulated mast cells isolated from LVAD supported myocardium decreased the [(3)H]-proline incorporation by 63% (P < 0.01) below baseline. Nonstimulated mast cells did not significantly alter the protein production over baseline. There was also a significant increase in the number of HSP-47-positive cells in DCM myocardium compared to normal (P < 0.01) and there was a shift toward normal after LVAD support (P < 0.01). CONCLUSION: We demonstrate that fibroblast protein production in vitro is significantly altered by mast cells and that the direction of change is dependent on whether myocardium was supported by LVAD. We suggest that under long-term LVAD support there is a phenotypic alteration in myocardial mast cells, which leads to a change in concentration and/or composition of mediators, capable of re-remodeling the myocardial matrix.  相似文献   
55.
56.
Abstract: The Nikkiso centrifugal pump was evaluated in elective adult open heard surgery in comparison with the BioMedicus pump. Ten patients using the Nikkiso pump (Group N), and 10 patients using the BioMedicus pump (Group B) were examined for (or to determine) hemato-biologic parameters and patient outcome data as well as pump controllability. During cardiopulmonary bypass (CPB), both pumps maintained systemic perfusion satisfactorily without any mechanical adverse event. Rotation speed of the Nikkiso centrifugal pump (3,580 ± 100 rpm) was significantly higher than that of the BioMedicus pump (3,170 ± 100 rpm; p < 0.05) whereas changes in free plasma hemoglobin, platelet count, blood urea nitrogen, and creatinine levels showed no significant differences between the two groups. Urine output in Group N for 30 min after the initiation of CPB (7.10 ± 1.50 ml/kg/h) was significantly higher than that in Group B (3.23 ± 0.46 ml/kg/h; p < 0.05). Patient outcome data were similar in both groups, such as duration of intensive care unit stay, hospital stay, postoperative intubation time, amount of postoperative bleeding, and amount of blood transfused. These equivalent results with the BioMedicus pump suggested that the Nikkiso pump can be used in open heart surgery as a reliable and atraumatic CPB pump.  相似文献   
57.
58.
The mechanism of death as a result of allograft ischemic heart disease is not well characterized. Ventricular tachycardia and fibrillation may not be the terminal events they often are in the general population. We report observations in a 41-year-old man with cardiac allograft arteriopathy who died suddenly while wearing an ambulatory monitor. The lethal rhythm was a progressive bradycardia terminating in asystole. Autopsy revealed epicardial and small vessel intramyocardial, coronary arteriopathy, and only mild allograft rejection. It is our belief that ischemia caused the bradycardic sudden death. We would like to hypothesize that prophylactic permanent pacemaker implantation may prevent bradycardic sudden death and improve survival in heart transplant patients with coronary disease.  相似文献   
59.
BACKGROUND: Multiple chronic conditions occurring in the same individual are associated with adverse health outcomes. In family practice, individuals are seen who, over time, may experience many different symptoms, illnesses and chronic diseases. Measures for defining multimorbidity, which incorporate the diverse range of health problems seen in population-based family practice, remain to be developed. We have investigated whether routinely collected consultation data could be used as the basis for a simple classification of multimorbidity that reflects an individual's overall health status. METHODS: Morbidity consultation data for 9,439 English patients aged 50 years and over in an 18-month time period were linked to their self-reported physical health status measured by Short-Form 12 at the end point. Associations between physical function and all-cause multimorbidity counts were estimated relative to single morbidity only, and between physical function and morbidity severity (185 morbidities categorized on four ordinal scales of severity) relative to persons who had not consulted about any of the 185. RESULTS: In the 18-month period, 19% had consulted for a single morbidity and 23% for six or more (a high multimorbidity count). An estimated 24% of poor physical function in the family practice consulting population may be attributable to high multimorbidity. There was an increasing strength of association between poor physical function and increasing severity of multimorbidity on all four severity scales. Estimated associations (adjusted odds ratios) of the most severe morbidity categories with poor physical function were, for each of the four scales, respectively, 5.6 for chronicity [95% confidence interval (CI) 4.4-7.1], 7.0 for time course (4.5-10.6) and 3.6 for health care use (2.0-6.6) and for patient impact (6.7; 5.2-8.8). CONCLUSIONS: Multimorbidity defined by using routinely collected family practice consultation data and classified by count and by severity was associated with poorer physical function. This approach offers the potential for systematic use of routine records to classify multimorbidity and to identify groups with high likelihood of poor physical status for needs assessment and targeted intervention.  相似文献   
60.
BACKGROUND & AIMS: Screening for colonic polyps is desirable. A new concept based on cross-sectional and endoscopic analysis of a magnetic resonance (MR) data set is presented. METHODS: Ex vivo autopsy colonic specimens, containing artificially placed polyps, were obtained and filled with a gadolinium-containing solution. Forty-four thin-section MR images were obtained in a 1.5-T MR scanner in 28 seconds. A three- dimensional endoscopic fly-through of these images was rendered. Fly- throughs and two-dimensional cross-sectional images were analyzed by two observers for the presence of polyps. RESULTS: The average sensitivity and specificity for the detection of polyps based on three- dimensional endoscopic MR colon imaging were 87% and 96%, respectively. Analysis of cross-sectional images showed an overall sensitivity and specificity of merely 57% and 84%, respectively. The difference in the interpretation of three-dimensional MR colonoscopy and two-dimensional cross-sections was statistically significant (P < 0.001). With three- dimensional MR colonoscopy, overall sensitivity for detection of polyps measuring < or =5 mm in length and diameter was 70%; for larger polyps, it increased to 95% (P < 0.01). CONCLUSIONS: The feasibility of an MR- based endoluminal assessment of the colon is shown. Minimal invasiveness, lack of radiation exposure, and high in vitro diagnostic accuracy warrant further investigation of this novel concept. (Gastroenterology 1997 Jun;112(6):1863-70)  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