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   624篇
  免费   28篇
  国内免费   14篇
儿科学   44篇
妇产科学   4篇
基础医学   61篇
口腔科学   17篇
临床医学   108篇
内科学   93篇
皮肤病学   8篇
神经病学   14篇
特种医学   191篇
外科学   31篇
综合类   32篇
预防医学   6篇
眼科学   2篇
药学   43篇
肿瘤学   12篇
  2020年   2篇
  2019年   2篇
  2018年   3篇
  2017年   3篇
  2016年   5篇
  2015年   5篇
  2014年   15篇
  2013年   12篇
  2012年   3篇
  2011年   7篇
  2010年   13篇
  2009年   18篇
  2008年   4篇
  2007年   16篇
  2006年   8篇
  2005年   11篇
  2004年   4篇
  2003年   11篇
  2002年   4篇
  2001年   8篇
  2000年   3篇
  1999年   20篇
  1998年   39篇
  1997年   47篇
  1996年   38篇
  1995年   39篇
  1994年   23篇
  1993年   26篇
  1992年   14篇
  1991年   20篇
  1990年   16篇
  1989年   13篇
  1988年   23篇
  1987年   23篇
  1986年   20篇
  1985年   18篇
  1984年   8篇
  1983年   8篇
  1982年   18篇
  1981年   12篇
  1980年   22篇
  1979年   4篇
  1978年   12篇
  1977年   22篇
  1976年   12篇
  1975年   8篇
  1974年   1篇
  1963年   2篇
  1943年   1篇
排序方式: 共有666条查询结果,搜索用时 0 毫秒
51.
A near-fatal reaction during granulocyte transfusion of a neonate   总被引:1,自引:0,他引:1  
Although reactions to granulocyte transfusions in neonates are rarely reported, we observed a near-fatal pulmonary reaction, presumably due to white cell antibodies, in a neonate with Rh hemolytic disease. The hemolytic disease was being treated with exchange transfusions, and at 2 days after the infant's birth, bacterial sepsis was suspected and granulocyte transfusions were begun. The first granulocyte transfusion (Day 3) was uneventful. Five minutes after the beginning of the second granulocyte transfusion (Day 4), severe respiratory distress, hypotension, bradycardia, cyanosis, and acidosis suddenly occurred. The infant's serum obtained after the reaction contained granulocytotoxic and B-lymphocytotoxic antibodies that reacted with leukocytes from the second granulocyte donor. Antibodies could not be detected either in the initial infant serum or in maternal serum. However, an antileukocyte antibody was present in the serum of a parous woman donor. We used plasma from this woman to prepare reconstituted whole blood for the exchange transfusion that we performed immediately preceding the second granulocyte transfusion. Despite the sequence of events, an irrefutable cause-and-effect mechanism could not be established because the properties of the donor and neonatal antibodies were similar, but not identical. However, this catastrophic event emphasizes both the potential for adverse effects of granulocyte transfusions in neonates and the need for caution when transfusing blood from parous women.  相似文献   
52.
Clinical improvement with dual chamber pacing bas largely been reported in patients suffering from hypertrophic obstructive cardiomyopathy and mainly attributed to the reduction of the subaortic pressure gradient. To be effective, pacing must induce a permanent and complete capture of the LV. In two patients of our collective, symptoms (angina and dyspnea NYHA Class III and/or syncopes) persisted or relapsed despite pacing. This was related to the inability to obtain full LV capture due to a too-short native PR interval. RF ablation of the AV junction was therefore performed in botb patients, resulting in permanent AV block in one and prolonged PR interval up to 310 ms in the second. Pacing was thereafter associated with an immediate and significant clinical improvement related to permanent LV capture, whatever the patient's activity. After RF ablation, the AV delay was set up to induce the best LV filling, as assessed by Doppler analysis of mitral flow. Our observations suggest that RF ablation or modification of the AV junction can be a successful procedure in some patients with residual or recurrent symptoms, when the latter result from a loss of capture or from the inability to program an AV delay tbat does not compromise the active component to LV filling. Doppler echocardiography is a simple and effective mean to assess the hemodynamic effect of AV interval modulation in this setting.  相似文献   
53.
慢性失眠症患者的思维特点   总被引:1,自引:0,他引:1  
目的:观察慢性失眠症患者的认知行为特征和其症状的产生及发展的关系,分析慢性失眠症患者的思维特点。方法:随机抽取北京中医药大学国医堂睡眠障碍门诊2004-01/07失眠症患者90例和配对睡眠正常者90人进行问卷调查,包括匹兹堡睡眠质量指数问卷、关于睡眠的非功能性的信念和态度量表修订版问卷以及思维控制问卷。匹兹堡睡眠质量指数问卷包括7个因子,每个因子按0~3等级记分,得分越高表示睡眠质量越差。关于睡眠的非功能性的信念和态度量表修订版由10个条目组成,5级评分,得分越高表示关于睡眠的非功能性的信念和态度越多。思维控制问卷由30个条目组成,包括6个纬度:认知转移、行为转移、社会支持、担心、惩罚和再评价,每个纬度的得分越高表示使用此种思维控制的方式越多。结果:发放问卷180份,回收完整问卷158份,有效率87.8%。最终病例组和对照组各79人,进入结果分析。①慢性失眠症患者关于失眠的短期影响、长期影响和对于睡眠的控制的非功能性的态度和信念得分均高于对照组(19.48±2.90,14.14±5.87;11.06±1.79,8.11±2.74;7.82±1.44,5.01±2.07;t=9.86,7.25,8.01,P<0.01)。②慢性失眠症患者使用担心和惩罚的思维控制方式得分高于睡眠正常组(10.7±2.6,8.5±2.9;11.6±2.8,9.0±3.1;t=5.08,5.43,P<0.01)。③关于睡眠的非功能性的信念和态度与担心和惩罚的思维控制方式呈正相关(r=0.41,0.24,P<0.01)。结论:对于失眠症患者进行认知行为治疗时,要注意纠正失眠症患者关于睡眠的非功能性的信念和态度,并指导失眠症患者学习有效的思维控制方式。  相似文献   
54.
Red cells preserved in extended-storage media are the standard product dispensed by many regional blood centers. When the red cells are intended for neonatal transfusion, concern exists about the safety of the relatively high quantities of additives present in these media. Definitive studies to address these concerns are not available. Therefore, to estimate the effects of additives and to delineate circumstances in which they might be harmful, the quantities transfused in defined clinical settings were calculated, and the following recommendations are offered for transfusing infants less than 4 months of age. First, red cells preserved in extended-storage media should present no substantive risks when used for small-volume (approximately 10 mL/kg) transfusions of premature infants and can be used without additional processing. Second, the risks of the most premature neonatal patients or those with severe renal and/or hepatic insufficiency cannot be defined clearly, and, because data are not available to ensure safety for these infants, removal of the additive medium and resuspension of the red cells in saline or albumin solution immediately before transfusion are recommended. Third, following a similar rationale, it seems prudent to avoid using entire units of red cells preserved in extended-storage media in massive transfusion settings (e.g., exchange transfusion, cardiac surgery, and extracorporeal membrane oxygenation). In these settings, the preservative medium should be removed and the red cells resuspended in the fluid that is most appropriate for the procedure that is planned. It must be emphasized that these recommendations are based on calculations and hypothetical settings, not actual data. Accordingly, they are tentative and should be altered as definitive information becomes available.  相似文献   
55.
Intraindividual Reproducibility of Heart Rate Variability   总被引:1,自引:0,他引:1  
Heart rate variability was determined from three consecutive Holter recordings performed on days 1, 7, and 28 in 17 normal subjects, in 13 patients with angiographically normal coronary arteries, and in 9 patients with remote myocardial infarctions. Group data of several time and frequency domain measures of heart rate variability were highly reproducible (correlation coefficients 0.629–0.894). However, some individuals exhibited considerably larger day-to-day variations in heart rate variability. Single heart rate indices differed by up to 50% between two Holter recordings. Such potential differences must be considered when repeated heart rate variability determinations are used to assess changes in neurocardiac reflex regulation or effects of therapeutic interventions.  相似文献   
56.
57.
Mycobacterial Infections After Renal Transplantation   总被引:5,自引:0,他引:5  
Mycobacterial infections occurred in 11 of 633 (1.7 per cent)recipients of successful renal transplants. There were no casesof tuberculosis in patients receiving chemoprophylaxis, butamongst those who did not receive prophylaxis disease occurredin six of the 27 (22 per cent) high-risk patients. The majorcause of morbidity during treatment was renal allograft rejection,largely due to reduction in immunosuppressive drug therapy.  相似文献   
58.
Platelet aggregation requires the binding of adhesive proteins such as fibrinogen to the heterodimer of membrane glycoproteins IIb (GPIIb) and IIIa (GPIIIa). Human erythroleukemia (HEL) cells synthesize both GPIIb and GPIIIa. Using poly(A+) RNA purified from HEL cells, we constructed a cDNA library in the lambda gt10 phage vector. This library was screened with a 38mer oligonucleotide derived from a platelet GPIIIa peptide, and three overlapping cDNAs were isolated. The three inserts encompassed 3.5 kilobases (kb), including the entire coding region of mature GPIIIa (2,286 basepairs, bp) and 1.3 kb of 3' untranslated sequence. All 222 residues determined directly from platelet GPIIIa tryptic peptides exactly matched the HEL cell-deduced amino acid sequence. The HEL cell sequence matched a previously reported endothelial cell cDNA sequence except for eight nucleotides. Five of these nucleotide differences were silent changes consistent with genetic polymorphisms. The other three differences resulted in changes in the deduced amino acid sequence of GPIIIa; reexamination of the endothelial cell cDNA sequence in these three areas revealed that it is actually identical to the HEL cell sequence. The virtual identity of the endothelial and HEL cell cDNA sequences provides direct evidence that GPIIIa is a subunit common to cell-adhesion receptors present in more than one cell type. We localized the gene for GPIIIa to chromosome 17, the same chromosome to which we had previously mapped the gene for GPIIb.  相似文献   
59.
目的:观察新生大鼠缺氧缺血性脑损伤后,海马发育过程中N-甲基-D-天冬氨酸受体的远期表达变化。方法:实验于2006-03/06在解放军第三军医大学新桥医院中心实验室完成。选用新生7日龄SD大鼠72只,按随机数字表法分为缺氧缺血性脑损伤组和假手术组,每组36只。各组又分为生后15d(n=6)、22d(n=6)、29d(n=6)、36d(n=12)及43d(n=6)5个时相点。①参照Rice法通过结扎7日龄大鼠左侧颈总动脉,吸入氧气体积分数为0.08的氮氧混合气,制成缺氧缺血性脑损伤模型,出现自发或夹尾左旋则证明模型制作成功。假手术组仅切开颈部皮肤,暴露左侧颈总动脉。②应用免疫组织化学法检测缺氧缺血后不同时点两组大鼠脑海马CA1区N-甲基-D-天冬氨酸受体NR1亚单位的表达(n=6),测量平均灰度值,灰度值越低,蛋白表达越强;生后36d时相点大鼠(n=6)利用Morris水迷宫测定学习记忆能力;最后应用电镜观察生后36d大鼠海马突触结构。结果:72只大鼠,全部进入结果分析,无脱失。①生后22-43d缺氧缺血性脑损伤组大鼠(缺氧缺血后15-36d)脑海马CA1区NR1平均灰度值分别为167.69±6.48,174.57±4.81,179.30±5.92,176.50±5.93,均显著高于同日龄假手术组148.96±4.91,151.17±6.37,152.06±9.86,156.32±6.86(P均<0.01)。②Morris水迷宫实验中,缺氧缺血性脑损伤组大鼠逃避潜伏期显著长于假手术组(48.87±9.47)s,(11.97±2.20)s,(P<0.01);原平台象限游泳距离/总游泳距离的百分比显著低于假手术组(14.45±3.85)%,(62.20±8.74)%(P<0.01)。③生后36d(缺氧缺血后29d),透射电镜下缺氧缺血性脑损伤组大鼠患侧海马突触后膜致密物较假手术组明显减少。结论:新生大鼠缺氧缺血性脑损伤后期存在海马N-甲基-D-天冬氨酸受体的表达下调,可能对大鼠远期空间学习记忆产生一定影响。  相似文献   
60.
Mid-trimester loss--appraisal of a screening protocol   总被引:1,自引:0,他引:1  
The main causes for mid-trimester loss are known. There is likely to be overlap with those of first trimester loss, but the proportions may be different. We wished to perform an aetiological survey in a large population of patients with a history of recurrent miscarriage, for possible explanations for their second trimester miscarriages. Database analysis of 636 patients attending a UK University Teaching Hospital dedicated miscarriage clinic between 1991 and 1996 revealed a 25% prevalence (n = 158) for second trimester miscarriage. Results from an investigative screening protocol were positive in 50% of cases: 33% (n = 52) tested positive for antiphospholipid syndrome (APS); 8% (n = 13) fulfilled strict criteria for cervical incompetence; there was a 4% prevalence of uterine anomaly; 3% for infection (n = 5) and 2% of patients (n = 3) proved to be hypothyroid. Importantly, dual pathology was found in 5% of patients with a history of second trimester miscarriage. As idiopathic mid-trimester loss is a diagnosis by exclusion, a high index of suspicion is required, as are modern diagnostic techniques.   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