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   464篇
  免费   20篇
  国内免费   4篇
耳鼻咽喉   6篇
儿科学   14篇
妇产科学   11篇
基础医学   58篇
口腔科学   13篇
临床医学   38篇
内科学   69篇
皮肤病学   23篇
神经病学   23篇
特种医学   14篇
外科学   56篇
综合类   5篇
一般理论   1篇
预防医学   54篇
眼科学   17篇
药学   31篇
中国医学   2篇
肿瘤学   53篇
  2024年   1篇
  2023年   8篇
  2022年   11篇
  2021年   28篇
  2020年   16篇
  2019年   27篇
  2018年   16篇
  2017年   13篇
  2016年   17篇
  2015年   11篇
  2014年   22篇
  2013年   26篇
  2012年   30篇
  2011年   34篇
  2010年   22篇
  2009年   15篇
  2008年   22篇
  2007年   19篇
  2006年   26篇
  2005年   19篇
  2004年   24篇
  2003年   30篇
  2002年   18篇
  2001年   3篇
  2000年   7篇
  1999年   2篇
  1998年   4篇
  1997年   2篇
  1996年   5篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1990年   2篇
  1989年   2篇
  1983年   1篇
  1977年   1篇
  1971年   1篇
排序方式: 共有488条查询结果,搜索用时 31 毫秒
141.
Complete tubular colonic duplication (CTCD) is exceedingly rare. The association of CTCD with an anorectal malformation is unusual. This malformation may be found unexpectedly at laparotomy. We present 3 cases of surgically proven neonate CTCD discovered at laparotomy for anal atresia. We reviewed the mode of clinical presentation, the imaging, and laparotomy findings. Our series illustrates that this rare disease presents perinatally in association with anal atresia, with or without other associated anomalies.  相似文献   
142.
143.
The Norwood operation (NO) with a right ventricle (RV)-to-pulmonary artery (PA) shunt (NRVPA) is reportedly associated with early hemodynamic advantage. Shunt strategy has been implicated in ventricular function. Outcomes after NRVPA compared with classic procedure as part of a strategy involving early bidirectional Glenn (BDG) procedure were analyzed with reference to RV, tricuspid, and neoaortic valve performance. Between January 2005 and December 2010, 128 neonates with hypoplastic left heart syndrome (HLHS) underwent NO. Controlled for aortic/mitral stenosis (AS–MS) subtype, 28 patients underwent NRVPA (group A), and 26 patients had classic procedure (group B). The patients with a non-HLHS single-ventricle anatomy and those who had undergone a hybrid approach for HLHS were excluded from the study. The mean age at NO was 6.8 ± 3.5 days in group A and 6.9 ± 3.6 days in group B. Transthoracic echocardiographic evaluation (TTE) after NO (TTE-1) at the midinterval between NO and BDG (TTE-2), before BDG (TTE-3), before Fontan (TTE-4), and at the last follow-up evaluation (TTE-5) was undertaken. Cardiac catheterization was used to assess hemodynamic parameters before the Glenn and Fontan procedures. The operative, interstage, and pre-Fontan survival rates for AS–MS after NO were respectively 88.1 % (90.3 % in group A vs. 84.7 % in group B; p = 0.08), 82.5 % (82.7 % in group A vs. 81.8 % in group B; p = 0.9), and 80.7 % (79.5 % in group A vs. 81.8 % in group B; p = 0.9). The median follow-up period was 39.6 months (interquartile range 2.7–4.9 months). The RV global function, mid- and longitudinal indexed dimensions, fractionated area change before BDG (TTE-1, TTE-2, TTE-3) and after BDG (TTE-4, TTE-5), and right ventricular end-diastolic pressure did not differ statistically between the groups (p > 0.05). No statistically significant difference in tricuspid or neoaortic intervention was found between the groups (p > 0.05). Controlled for the AS–MS HLHS subtype, shunt strategy showed no midterm survival or hemodynamic (ventricular or valve) impact. At midterm, the follow-up need for neoaortic or tricuspid valve surgical intervention was not affected by shunt selection. The structural ventricular adaptation after reversal of shunt physiology was irrespective of shunt strategy.  相似文献   
144.
ObjectivesThe currently available commercial dental resin composites have limitations in use owing to the high viscosity and water sorption of Bisphenol A glycidyl methacrylate (BisGMA). The objective of this study was to obtain a BisGMA analog with reduced viscosity and hydrophilicity for potential use as an alternative to BisGMA in dental resin composites.MethodsThe targeted chlorinated BisGMA (Cl-BisGMA) monomer was synthesized via the Appel reaction. The structural modification was confirmed via 1H- and 13C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and mass spectrometry. Five resin mixtures (70:30 wt.%: F1 = BisGMA/TEGDMA; F2 = Cl-BisGMA/TEGDMA; F3 = Cl-BisGMA only; F4 = Cl-BisGMA/BisGMA; F5 contained 15% TEGDMA with equal amounts of BisGMA and Cl-BisGMA) were prepared. The viscosity, degree of double-bond conversion (DC), water sorption (WSP), and solubility (WSL) were tested. Cell viability and live/dead assays, as well as cell attachment and morphology assessments, were applied for cytotoxicity evaluation.ResultsCl-BisGMA was successfully synthesized with the viscosity reduced to 7.22 (Pa s) compared to BisGMA (909.93, Pa s). Interestingly, the DC of the F2 resin was the highest (70.6%). By the addition of equivalence concentration of Cl-BisGMA instead of BisGMA, the WSP was decreased from 2.95% (F1) to 0.41% (F2) with no significant change in WSL. However, the WSL increased with high Cl-BisGMA content. Biological tests revealed that all the resins were biocompatible during CL1 incubation.SignificanceThe experimental resins based on Cl-BisGMA exhibited improved properties compared with the control samples, e.g., biocompatibility and lower viscosity, indicating that Cl-BisGMA can be considered as a potential monomer for application in dental resin composites.  相似文献   
145.
The decreased expression of the sarcoplasmic reticulum Ca2+-ATPase associated with cardiac hypertrophy was investigated in cultured neonatal rat cardiac myocytes. Northern blot analysis indicated a significant 55–60% decrease in Ca2+-ATPase mRNA levels and after 12 and 24 h of treatment with the phorbol ester phorbol myristate acetate (PMA). Myocytes treated with the phorbol ester for 80 h showed a significant 34% decrease (relative to vehicle-treated control cells) in the levels of Ca2+-ATPase protein, and a significant 38% increase in the levels ofα-sarcomeric actin, as assessed by Western blot analysis using specific antibodies. Immunocytochemistry of myocytes treated for 72 h with the phorbol ester revealed a hypertrophied cell morphology, and showed a marked decrease in Ca2+-ATPase staining intensity. Contractile calcium transients were evaluated through the use of indo-1. It was found that thet1/2for the decline of calcium transient was significantly prolonged by PMA treatment (0.51±0.15) when compared to controls (0.38±0.17,P<0.001). Treatment of myocytes with endothelin-1 also led to a 35% decrease in sarcoplasmic reticulum Ca2+-ATPase mRNA levels. It is concluded that phorbol ester treatment of neonatal rat cardiac myocytes induces similar changes in Ca2+-ATPase gene expression as observedin vivoin the hypertrophied and failing heart. The observed prolongation int1/2for [Ca2+]idecline might be due to the observed depressed levels for sarcoplasmic reticulum Ca2+-ATPase in PMA treated cells.  相似文献   
146.
PURPOSE: To compare the efficacy of tramadol and morphine for intra- and postoperative analgesia in patients undergoing laparoscopic cholecystectomy. METHODS: In a prospective, randomized, double-blind study 100 patients were allocated randomly into two groups. Ten minutes before induction of anaesthesia, patients in group 1 received 100 mg tramadol and those in group 2 received 10 mg morphine i.v. Anaesthesia was induced with 5 mg.kg-1 thiopental and was maintained with O2, N2O plus isoflurane with additional doses of tramadol or morphine as decided by the attending anaesthetist. Postoperatively, patients in group 1 and group 2 received tramadol and morphine, respectively, from a patient-controlled analgesia (PCA) device. Pain, analgesic consumption, vital signs and side effects were recorded postoperatively for 24 hr. RESULTS: Intraoperative consumption of tramadol and morphine were 137 +/- 37 and 12.2 +/- 3 mg, respectively. Compared with morphine, patients receiving tramadol had higher blood pressures and required greater mean ETisQ to control haemodynamic variables (P < 0.05). Postoperatively, there were no differences in observer pain score or visual analogue pain score during the first 24 hr between groups except at 30, 45, and 90 min where patients in the tramadol group reported higher pain scores (P < 0.05). The cumulative, 24 hr PCA consumption was 111 +/- 93 and 7.5 +/- 6.6 mg of tramadol and morphine, respectively. CONCLUSIONS: There was no difference between the use of tramadol and morphine to treat pain after laparoscopic cholecystectomy from 90 min after the end of surgery. Morphine was more effective than tramadol as an intraoperative analgesic.  相似文献   
147.
The potential protective role of alpha-lipoic acid (alpha-LA) in acetaminophen (APAP)-induced hepatotoxicity and nephrotoxicity was investigated in rats. Pretreatment of rats with alpha-LA (100mg/kg) orally protected markedly against hepatotoxicity and nephrotoxicity induced by an acute oral toxic dose of APAP (2.5 g/kg) as assessed by biochemical measurements and by histopathological examination. None of alpha-LA pretreated animals died by the acute toxic dose of APAP. Concomitantly, APAP-induced profound elevation of nitric oxide (NO) production and oxidative stress, as evidenced by increasing of lipid peroxidation level, reducing of glutathione peroxidase (GSH-Px) activity and depleting of intracellular reduced glutathione (GSH) level in liver and kidney, were suppressed by pretreatment with alpha-LA. Similarly, daily treatment of rats with a smaller dose of alpha-LA (25mg/kg) concurrently with a smaller toxic dose of APAP (750 mg/kg) for 1 week protected against APAP-induced hepatotoxicity and nephrotoxicity. This treatment also completely prevented APAP-induced mortality and markedly inhibited APAP-induced NO overproduction and oxidative stress in hepatic and renal tissues. These results provide evidence that inhibition of NO overproduction and maintenance of intracellular antioxidant status may play a pivotal role in the protective effects of alpha-LA against APAP-induced hepatic and renal damage.  相似文献   
148.
BACKGROUND: Acute consumption of fat-free fluid milk after resistance exercise promotes a greater positive protein balance than does soy protein. OBJECTIVE: We aimed to determine the long-term consequences of milk or soy protein or equivalent energy consumption on training-induced lean mass accretion. DESIGN: We recruited 56 healthy young men who trained 5 d/wk for 12 wk on a rotating split-body resistance exercise program in a parallel 3-group longitudinal design. Subjects were randomly assigned to consume drinks immediately and again 1 h after exercise: fat-free milk (Milk; n = 18); fat-free soy protein (Soy; n = 19) that was isoenergetic, isonitrogenous, and macronutrient ratio matched to Milk; or maltodextrin that was isoenergetic with Milk and Soy (control group; n = 19). RESULTS: Muscle fiber size, maximal strength, and body composition by dual-energy X-ray absorptiometry (DXA) were measured before and after training. No between-group differences were seen in strength. Type II muscle fiber area increased in all groups with training, but with greater increases in the Milk group than in both the Soy and control groups (P < 0.05). Type I muscle fiber area increased after training only in the Milk and Soy groups, with the increase in the Milk group being greater than that in the control group (P < 0.05). DXA-measured fat- and bone-free mass increased in all groups, with a greater increase in the Milk group than in both the Soy and control groups (P < 0.05). CONCLUSION: We conclude that chronic postexercise consumption of milk promotes greater hypertrophy during the early stages of resistance training in novice weightlifters when compared with isoenergetic soy or carbohydrate consumption.  相似文献   
149.
Country-specific hip fracture incidence rates (IRs) and longevity allow the Fracture Risk Assessment Tool (FRAX) to be adapted to individual countries. Secular trends can affect tool calibration. Data on hip fracture IRs in the Middle East is scarce, and long-term secular trend studies are nonexistent. Using the Ministry of Public Health hip fracture registry, we calculated age- and sex-specific hip fracture IRs in Lebanon, from 2006 to 2017, among individuals aged ≥50 years. We used Kendall's tau-b (τb) test to determine the correlation between time and hip fracture IRs, and calculated both the annual % change in IRs and the % change in IR compared to the baseline period (2006 to 2008). The registry recorded 6985 hip fractures, 74% at the femoral neck, 23% intertrochanteric, and 3% subtrochanteric. Men constituted 32% of the population, and were significantly younger than women (76.5 ± 11.0 years versus 77.7 ± 10.3 years; p < 0.001). Annual overall IRs, per 100,000, ranged from 126.6 in 2014 to 213.2 in 2017 in women, and 61.4 in 2015 to 111.7 in 2017 in men. The average women to men IR ratio was 1.8 (range, 1.5 to 2.1). IRs steadily increased with age, and IR ratios increased in parallel in both sexes, with a steeper and earlier rise (by 5 years) in women. Data showed a consistent decline in hip fracture IRs starting in 2006 in women, and in 2009 in men. There was a significant negative correlation between time (2006 to 2014) and hip fracture IRs in women (τb = −0.611, p = 0.022) but not in men (τb = −0.444, p = 0.095). The steady decrease in IRs reversed after 2015 in both sexes. This long-term data on secular trends in the Middle East is novel and consistent with worldwide changes in hip fracture rates. The impact of such changes on national FRAX-derived estimates is unclear, should be assessed, and may necessitate an update in the FRAX Lebanon calculator. © 2019 American Society for Bone and Mineral Research.  相似文献   
150.
When antiepileptic drugs fail to relieve seizures adequately in children and adolescents, more invasive therapies such as epilepsy surgery and an implanted device to stimulate the vagus nerve should be considered. Temporal lobectomy is an effective treatment of complex partial and secondarily generalized tonic-clonic seizures arising in the mesial structures or lateral temporal neocortex. Excellent outcomes (seizure free or rare, nondisabling seizures) are achieved in at least 70% of children. The most common adverse effect is a superior quadrant field cut that is usually asymptomatic. Transient and more long-lasting language difficulties have been reported when the surgery involves the dominant temporal lobe. The excellent outcome rate for extratemporal surgery ranges from approximately 20% to 80%, with better results seen in patients with an identifiable lesion. Potential morbidity is related to the region of resected neocortex. Corpus callosotomy is an excellent procedure for palliation but is not a cure for seizures that cause falls, with substantial improvement seen in more than 80% of patients. Potential adverse effects include more intense focal seizures and dysphasia, depending on the developmental level of the individual. Hemispherectomy provides seizure relief in 60% to 80% of patients with hemispherical pathologies such as Sturge-Weber or Rasmussen syndromes. Operative mortality has been reported in the range of 0% to 6%; other morbidities include infection and hydrocephalus. Stimulation of the vagus nerve has reduced partial seizures by 50% or more in approximately one third of patients. No adverse cognitive or systemic effects are associated with use of the implanted vagus nerve stimulator.  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