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   31742篇
  免费   2006篇
  国内免费   81篇
耳鼻咽喉   271篇
儿科学   729篇
妇产科学   592篇
基础医学   4494篇
口腔科学   696篇
临床医学   2928篇
内科学   6095篇
皮肤病学   526篇
神经病学   3522篇
特种医学   1353篇
外国民族医学   55篇
外科学   4417篇
综合类   382篇
一般理论   10篇
预防医学   2499篇
眼科学   890篇
药学   2125篇
中国医学   33篇
肿瘤学   2212篇
  2022年   203篇
  2021年   465篇
  2020年   298篇
  2019年   460篇
  2018年   531篇
  2017年   439篇
  2016年   500篇
  2015年   659篇
  2014年   855篇
  2013年   1223篇
  2012年   1857篇
  2011年   1933篇
  2010年   1073篇
  2009年   992篇
  2008年   1750篇
  2007年   1881篇
  2006年   1794篇
  2005年   1820篇
  2004年   1779篇
  2003年   1651篇
  2002年   1589篇
  2001年   451篇
  2000年   401篇
  1999年   425篇
  1998年   374篇
  1997年   333篇
  1996年   284篇
  1995年   263篇
  1994年   235篇
  1993年   230篇
  1992年   272篇
  1991年   240篇
  1990年   214篇
  1989年   241篇
  1988年   221篇
  1987年   224篇
  1986年   204篇
  1985年   193篇
  1984年   245篇
  1983年   205篇
  1982年   246篇
  1981年   221篇
  1980年   203篇
  1979年   187篇
  1978年   161篇
  1977年   115篇
  1976年   147篇
  1975年   136篇
  1974年   163篇
  1973年   120篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
IAFP     
  相似文献   
132.
133.
The origin of image artifacts in an off-resonance spin-locking experiment is shown to be imperfections in the excitation flip angle. A pulse sequence for off-resonance spin locking is implemented that compensates for imperfections in the excitation flip angle through an off-resonance rotary echo. The off-resonance rotary echo alternates the frequency offset and phase of the RF transmitter during two spin-locking pulses of equal duration. The underlying theory is detailed, and MR images demonstrate the effectiveness of the technique in agarose gel phantoms and in in vivo human brain at 3T.  相似文献   
134.
OBJECTIVE: Standard lung donor criteria have been established on opinions and individual experiences rather than on existing evidence. Since the scarcity of donor organs is one of the major limitations to lung transplantation, extension of donor lung criteria might considerably increase the donor pool. This study therefore evaluates the outcome, achieved with the use of extended donors versus standard donors and aims to redefine lung donor criteria. METHODS: We performed a retrospective analysis of 98 consecutive primary lung transplantations from 94 donors from 1/2001 to 12/2002. Donors were classified as extended if they fulfilled at least one criteria: age >55 years, PaO(2) at FiO(2)/PEEP 5 <300mmHg, tobacco history >20 pack years, inhalative drug abuse, presence of infiltration on chest X-ray or purulent secretions at bronchoscopy. Recipients were stratified in two groups according to whether they received a 'standard' or 'extended' organ. Postoperative complications, extubation time, ICU and hospital stay and survival were compared. RESULTS: Twenty-three (24.5%) donors were extended. Twenty-six recipients (26.55%) received organs from extended donors. Differences in intubation times (12+/-2 days standard vs. 14+/-5 days extended, P=0.70), ICU stay (16+/-2 days standard vs. 18+/-5 days extended, P=0.74) and hospital stay (38+/-4 days standard vs. 40+/-6 days extended, P=0.71) were not statistically significant. Postoperative bleeding rates were comparable (n=14 standard vs. n=3 extended) as well as bronchial anastomotic complications (n=7 standard vs. n=3 extended). Three months survival was 88.89% in the standard group vs. 92.31% in the extended group. One year survival is comparable as well with 81.94 vs. 84.62%, respectively. CONCLUSIONS: The use of lung donors who fail to meet standard criteria does not impair short and medium term results compared to standard lung donors. The impact on long term development of BOS has yet to be evaluated. The strict application of standard lung donor criteria excludes a considerable number of lungs potentially suitable for transplantation, thus liberalisation of donor criteria might help to overcome donor shortage.  相似文献   
135.
Bronchiolitis obliterans (BO) is a survival-limiting factor in lung transplantation. There are no common BO markers in use. Since BO is associated with extracellular matrix remodeling, we asked whether matrix metalloproteases (MMPs) and their tissue inhibitors (TIMPs) could serve as BO markers. In 72 lung transplant patients (34 BO syndrome (BOS) 0, 15 BOS 0-p, and 23 BOS 1) serum and broncho-alveolar lavage (BAL) MMP and TIMP levels were examined by ELISA. The BAL cell counts were additionally analyzed. The serum MMP-2, MMP-8, MMP-9 and TIMP-2 levels were not different in all groups. In contrast, the BAL MMP-8, -9 and TIMP-1 levels were significantly elevated in BOS 0-p (p = 0.003; p = 0.007; p = 0.0003, respectively) and BOS 1 (p = 0.003; p = 0.001; p = 0.0004, respectively) as compared to BOS 0 patients. The BAL MMP-8, -9 and TIMP-1 levels were significant predictors of BOS 0-p (p = 0.01; p = 0.01; p = 0.01, respectively) and BOS-1 (p = 0.007; p = 0.01; p = 0.006, respectively) in receiver operating characteristic analysis. Except for BAL macrophages that were significantly decreased in BOS 0-p versus BOS 0 patients; other cell counts were not different between the groups. BAL MMP-8, -9 and TIMP-1 might be useful markers to detect BO in lung transplant patients.  相似文献   
136.
AIMS: Autoimmune diseases such as Addison's or coeliac disease can contribute to hypoglycaemia or malabsorption and are more common in Type 1 diabetes (T1DM). This brief report describes the prevalence of known and newly detected autoimmune disease in clinical islet transplant candidates with longstanding T1DM and severe hypoglycaemia and/or glycaemic lability who are routinely screened for coexisting autoimmune disease. METHODS: One hundred and twenty-four C-peptide negative T1DM subjects [77 (62%) female, mean age 44 +/- 9 years, diabetes duration 28 +/- 11 years, body mass index 24.9 +/- 3.5 kg/m(2)] with indications for clinical islet transplantation at the University of Alberta were screened for autoimmune disease by history and measurement of anti-transglutaminase antibodies (positive > 10 U/ml), 09.00 h cortisol (followed by adrenocorticotrophic hormone-stimulation if < 495 nmol/l) and thyroid-stimulating hormone to determine the prevalence of coeliac disease, Addison's disease and autoimmune thyroid disease, respectively. RESULTS: Forty per cent of subjects had one or more coexisting autoimmune disease. The prevalence of autoimmune disease was 35%, coeliac disease 8% and Addison's disease 1.6%. In 11 individuals (9%), one or more autoimmune disease were newly detected (seven coeliac disease and five thyroid disease). Seven of 10 cases of coeliac disease were newly detected. A gluten-free diet in individuals with newly diagnosed coeliac disease reduced gastrointestinal symptoms, but indications for clinical islet cell transplantation persisted. CONCLUSIONS: Coexisting autoimmune disease is common in candidates for clinical islet cell transplantation. Screening in this group identified a substantial number of previously unrecognized cases. Clinicians should consider the presence of autoimmune disease even in the absence of classical symptoms.  相似文献   
137.
138.
139.
Ein 57-jähriger Bankangestellter stellt sich wegen seit Monaten bestehender Abgeschlagenheit und Müdigkeit vor. Anamnese: seit 3 Jahren dokumentierte Hypercholesterinämie (Gesamtcholesterin 350 mg/dl) und Hypertriglyzeridämie (Triglyzeride 430 mg/dl), zurzeit mit einem Statin behandelt, ferner seit einem 1/2 Jahr symptomatische Gicht (letzter Anfall vor 4 Wochen), jetzt mit 300 mg Allopurinol behandelt, sowie Claudicatio intermittens (Gehstrecke 300 m) bekannt. Seit der Jugend ist zudem ein allergisches Asthma bekannt, das mit inhalativen Steroiden und einem lang wirkenden β-Mimetikum behandelt wird. Die Frage nach Dyspnoe, Thoraxschmerzen oder einer plötzlich auftretenden Hautblässe wird verneint.Körperliche Untersuchung: Gewicht 89,2 kg, Größe 1,78 m, Blutdruck 210/90 mmHg. Die 24-h-Blutdruckmessung zeigt eine nächtliche Blutdrucksenkung von 15% systolisch und 12% diastolisch. In der Routinelaboruntersuchung keine Auffälligkeiten, insbesondere ausgeglichene Elektrolyte, normale Nierenfunktion. Im Urin-Stix keine Erythrozyt- oder Proteinurie. Verlauf: Der Patient erhält zunächst 5 mg Amlodipin und wird bezüglich nichtmedikamentöser Maßnahmen eingehend beraten. Bei einer Wiedervorstellung nach 3 Wochen hat er 1,5 kg an Gewicht abgenommen und einen Blutdruck von 170/85 mmHg.  相似文献   
140.
BACKGROUND: Glucose is an accepted osmotic agent for peritoneal dialysis (PD) although it has several drawbacks. Some of these drawbacks have been addressed by the introduction of solutions with low glucose degradation products and physiological pH in dual-chambered bags. Despite this achievement, there is a need for alternative osmotic agents.This randomized clinical trial analyzes 3-month's clinical experience with a mixture of 0.6% amino acids and 1.4% glycerol. METHODS: The study was performed at the renal units of the University Hospitals Ghent, Belgium, and Utrecht, The Netherlands. Stable PD patients were randomized for either protocol A (test solution, n = 5) or protocol B (control regimen, n = 5). In both protocols, there was a run-in phase of 1 month with a dialysis regimen of 2 x 2 L 2.27% glucose solution (Dianeal; Baxter, Nivelles, Belgium), 1 x 2 L Extraneal (Baxter), and 1 x 2 L glucose solution (Dianeal). After this month-long run-in period, patients in group A received during 3 months 2 x 2 L amino acid/glycerol solution, 1 x 2 L Extraneal, and at least 1 x 2 L of a classic glucose solution. RESULTS: Glucose absorption decreased in the test group during the test phase (from 84.2 +/- 8.7 to 11.7 +/- 11.6 g/24 hours, p = 0.001). Dialysate levels of cancer antigen 125 (CA125) increased in the test group, from 17.5 +/- 11.0 to 32.4 +/- 4.6 units/L (p = 0.04), whereas, in the control group, the levels remained stable (15.5 +/- 8.7 and 14.9 +/- 9.8 units/L respectively, p = 0.4).There were no differences in serum urea, serum bicarbonate, serum osmolarity, serum albumin, or parameters related to skin-fold thickness or serum glycerol levels between control and test solutions. No differences were observed in obtained ultrafiltration after a 4-hour dwell with 2.27% glucose or the test solution, both measured at week 4 of the run-in period and week 12 of the test period. CONCLUSION: This study demonstrated that the use of a new 0.6% amino acid/1.4% glycerol-containing dialysis solution is safe and well tolerated. Glucose load was reduced significantly and dialysate CA125 levels improved significantly. Ultrafiltration was comparable with that of a 2.27% glucose solution. All these factors, in combination with the potential nutritional benefits, can contribute to a beneficial impact on the success of the PD technique. Further long-term studies in larger patient groups are warranted to explore the potential of this promising new solution.  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