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   222篇
  免费   18篇
儿科学   6篇
妇产科学   2篇
基础医学   18篇
口腔科学   2篇
临床医学   67篇
内科学   75篇
皮肤病学   10篇
神经病学   7篇
外科学   19篇
预防医学   9篇
药学   25篇
  2022年   3篇
  2021年   1篇
  2017年   7篇
  2016年   7篇
  2015年   7篇
  2014年   8篇
  2013年   11篇
  2012年   2篇
  2011年   2篇
  2010年   13篇
  2009年   17篇
  2008年   3篇
  2007年   1篇
  2006年   4篇
  2005年   3篇
  2004年   2篇
  2003年   1篇
  2002年   2篇
  2001年   2篇
  2000年   4篇
  1999年   5篇
  1998年   10篇
  1997年   13篇
  1996年   14篇
  1995年   17篇
  1994年   9篇
  1993年   4篇
  1992年   5篇
  1991年   6篇
  1990年   7篇
  1989年   5篇
  1988年   4篇
  1987年   4篇
  1986年   2篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1978年   2篇
  1969年   1篇
  1967年   1篇
  1959年   3篇
  1958年   1篇
  1957年   10篇
  1956年   3篇
  1955年   1篇
  1954年   1篇
  1937年   2篇
排序方式: 共有240条查询结果,搜索用时 31 毫秒
151.
PADELETTI, et al. : Atrioventricular Interval Optimization in the Right Atrial Appendage and Interatrial Septum Pacing: A Comparison Between ECHC and Peak Endocardial Acceleration. Interatrial septum pacing (IASP) reduces interatrial conduction time and consequently may interfere with atrioventricular delay (AVD) optimization. We studied 14 patients with an implanted BEST Living system device able to measure peak endocardial acceleration (PEA) signal. The aims of our study were to compare the (1) optimal AVD (OAVD) in right atrial appendage pacing (RAAP) and IASP, and (2) OAVD derived by the PEA signal versus OAVD derived by Echo/Doppler evaluation of the left ventricular filling time (LVFT) and cardiac output (CO). Measurements were performed in DDD VDD modes Eight patients (group A) had RAAP and six patients (group B) had IASP. In group A, OAVD measured by LVFT, CO, and PEA was 185 ± 23 ms , 177 ± 19 ms , and 192 ± 23 ms in DDD and 147 ± 19 ms , 135 ± 27 ms , and 146 ± 20 ms in VDD, respectively. OAVD measured by LVFT, CO, and PEA was significantly longer in DDD mode than in VDD (P < 0.01, P < 0.01, P < 0.001 ). In group B, OAVD measured by LVFT, CO, and PEA was 116 ± 19 ms , 113 ± 10 ms , and 130 ± 30ms in DDD and 106 ± 16 ms , 96 ± 15 ms , and 108 ± 26 ms in VDD, respectively. No statistical differences were observed between DDD and VDD. Significant correlations between OAVDs PEA derived and OAVDs LVFT and CO derived were observed (r = 0.71, r = 0.69, respectively ). When new techniques of atrial stimulation, as IASP, are used an OAVD shorter and similar in VDD and DDD has to be considered. The BEST Living system could provide a valid method to ensure, in every moment, the exact required OAVD to maximize atrial contribution to CO.  相似文献   
152.
Coronary bifurcation lesions represent an area of ongoing challenge in interventional cardiology. Contemporary studies using drug-eluting stents report a reduction in main vessel (MV) restenosis; however, residual stenosis and restenosis at side-branch ostium remain an issue. Multiple two-stent bifurcation strategies exist, including T-stenting, V-stenting, simultaneous kissing stenting, culotte stenting, and crush stenting technique. Each strategy has its own advantages and disadvantages, but on the basis of results of numerous randomized trials, the provisional approach of implanting one stent on the main branch has became the default approach to most bifurcation lesions. Dedicated bifurcation stents have been designed to specifically address some of the shortcomings of the conventional percutaneous approach to bifurcation intervention. The majority of the devices are aimed at facilitating the provisional approach. Dedicated bifurcation stents should enable all operators to treat the side-branch ostium simultaneously with the main branch, preserving a safe, permanent access to side branch during the procedure. In the future, the use of these new devices will probably enhance the interaction between adequate mechanical scaffolding and accurate delivery of the appropriate dosage of any new antirestenosis drugs. There are currently 11 devices available that either have completed or are undergoing first-in-man trials. The development of further drug-eluting platforms and larger controlled studies should demonstrate their clinical applicability, efficacy, and safety before they are widely incorporated into daily practice.  相似文献   
153.
Background: Large patent foramen ovale (PFO), spontaneous right‐to‐left shunt, large atrial septal aneurysm (ASA), coagulation abnormalities, and prominent eustachian valve (EV) have all been independently suggested as risk factors for recurrent stroke. We sought to retrospectively evaluate risk of stroke and impact of transcatheter PFO closure in patients with concurrent large PFO, spontaneous right‐to‐left shunt, large ASA, coagulation abnormalities, and prominent EV. Methods: Between March 2006 and October 2008, 36 (mean age 44 ± 10.9 years, 28 females) out of 120 consecutive patients referred to our center for transcatheter PFO closure had concomitant diagnosis of (a) large PFO on transcranial Doppler (TCD) and transesophageal echocardiography (TEE), (b) spontaneous right‐to‐left shunt on TCD, (c) large ASA, (d) prominent EV, and (e) coagulation abnormalities. All patients fulfilled the standard current indications for transcatheter closure and underwent preoperative TEE and brain magnetic resonance imaging (MRI), with subsequent intracardiac echocardiographic‐guided transcatheter PFO closure. Results: Compared to the remaining PFO population in the same period, patients with all five concomitant features had more ischemic brain lesions on MRI, previous history of recurrent stroke, more frequently a history of venous thromboembolism, and more severe migraine with aura. The concomitance of all the features confers the highest risk of recurrent stroke (OR 9.9, 3.0–18 [95% CI], P < 0.001). Conclusions: Despite its small sample size and nonrandomized retrospective nature, this is the first study to suggest that patients with concurrence of all the investigated characteristics have potentially a higher risk of stroke compared to controls. We thus propose the CARP criteria as a basis for further larger, longitudinal studies to assess the potential benefits of transcatheter closure in this patient subset in the absence of clinical recurrent stroke.  相似文献   
154.
Ultra High‐Density Multipolar Mapping With Double Ventricular Access . Background: Analogous to the use of circular loop catheters to guide ablation around the pulmonary veins, it may be advantageous to use a multipolar catheter in the ventricle for rapid mapping and to guide ablation. We describe a technique using double access into the left ventricle for multipolar electroanatomic mapping and ablation of scar‐mediated ventricular tachycardia (VT). Methods: Double access into the left ventricle was obtained via transseptal technique. Endocardial mapping was performed via the first transseptal sheath using a steerable duodecapolar catheter. Higher density mapping was performed in areas of dense scar (<0.5 mV) and border zone (0.5–1.5 mV). All late potentials (LPs) observed on the 20 poles were tagged and pacemapping was performed at these sites for comparison with the clinical or induced VT 12‐lead template. If VT was hemodynamically tolerated, entrainment mapping was attempted at sites demonstrating diastolic activity. Ablation was performed through the second transseptal sheath with an open‐irrigated catheter at target sites identified by LPs, pacemapping, and/or entrainment on the duodecapolar catheter. Results: Seventeen patients (88% ischemic cardiomyopathy) underwent electroanatomic mapping and ablation with double transseptal access. The mean number of endocardial mapping points was 819 ± 357 with an average mapping time of 31 ± 7 minutes. The mean number of VTs induced was 2.8 ± 1.6, mean cycle length 418 ms ± 101. LPs were seen in all patients during endocardial mapping with the duodecapolar catheter. Good (56%) and perfect (44%) pacemaps were seen in all patients when performed. Concealed entrainment, guided by the earliest diastolic activity seen on the duodecapolar catheter, was demonstrated in 4 patients (24%). Acute success was achieved in 94% of patients with complete success in 47% and partial success in 47%. The intermediate success rate (free of VT recurrence) was 69%, with an average follow‐up of 8 ± 3 months. Conclusion: Mapping and ablation of scar‐mediated VT using a multipolar catheter results in ultra high‐density delineation of the left ventricular substrate. A novel double ventricular access strategy has the potential to facilitate identification of LPs, pacemapping, and entrainment mapping. (J Cardiovasc Electrophysiol, Vol. 22, pp. 49‐56, January 2011)  相似文献   
155.
156.
157.
AIM: There is wide consensus that the lowest success rate of extracorporeal shock wave lithotripsy (ESWL) is in the complete clearance of renal stones located in the lower calyces. We assess the effectiveness of extracorporeal shock wave lithotripsy monotherapy for lower pole renal calculi to determine the relationship between the spatial anatomy of lower pole and the outcome of ESWL. METHODS: We evaluated 107 patients who were treated for solitary lower pole renal stones less than 20 mm in diameter with ESWL. The spatial anatomy of the lower pole, as defined by the lower infundibulopelvic angle, infundibular length and infundibular width, was measured by preoperative intravenous pyelography, while the stone location and size were determined by using abdominal plain X-ray. All patients were followed up at 1 and 3 months with abdominal plain X-ray and ultrasonography. RESULTS: Only 62 patients (58%) became stone free, while 45 (42%) retained residual fragments. A small lower infundibulopelvic angle, a long infundibular length and a tight infundibular width are unfavorable for stone clearance after ESWL. CONCLUSIONS: ESWL is the treatment of choice for most renal and ureteral stones. However, stone clearance from the lower pole following ESWL is poor and significantly affected by the inferior pole collecting system anatomy. Therefore, we believe it is important to evaluate these anatomical factors when deciding on the best treatment for lower pole renal calculi.  相似文献   
158.
159.
The Mycobacterium tuberculosis chaperonin 10 protein and fragments corresponding to sequences 59-99, 51-99 and 26-99 were synthesised by the solid-phase methodology using a double coupling protocol and without the aid of capping agents. After the final acid cleavage using the low TFMSA-high HF protocol the polypeptides were purified by either the ion exchange chromatography/RP-HPLC combination or the isoelectric separation carried out in solution and followed by semi-preparative RP-HPLC. Comparison of the results obtained through the two approaches indicated that in general the isoeletricfocusing/HPLC combination was superior both in terms of recovery of final material and its purity. The advantages found were as follows: (i) Unlike ion exchange chromatography, no tailoring of the separation conditions is required. (ii) Several consecutive focusings can be carried out in progressively narrower pH gradients. This increases the separation resolution without the need of changing other separation parameters, (iii) Very little manipulation is needed, and each focusing requires 3-5 h. (iv) Full compatibility with non-ionic denaturants such as 8 M urea. This increases solubility so that using the ROTOFOR instrument described here 50-100 mg crude polypeptide can be processed daily. Thus the isoelectric focusing technique carried out in solution is a valid and inexpensive alternative to ion exchange chromatography. © Munksgaard 1997.  相似文献   
160.
This study was designed to test the hypothesis that a short treatment course of 1,25(OH)2D3elicits a stimulation of osteoblast activity without any action on the osteoclast. To test this, oral daily doses of 0.5μg or 1μg of 1,25(OH)2D3were administered for 7 days to two groups (n=5 andn=7, respectively) of postmenopausal women with low bone mineral density. Markers of osteoblast activity, i.e. osteocalcin (BGP), total alkaline phosphatase activity (ALP) and bone alkaline phosphatase activity (BALP), and markers of osteoclast activity, i.e. hydroxylysyl-pyridinoline (Pyr), lysyl-pyridoline (D-Pyr), and galactosyl-hydroxylysine (GHyl) were measured in plasma and in fasting urinary samples, respectively, at sequential times during and after 1,25(OH)2D3administration. It resulted that short term 1μg 1,25(OH)2D3oral administration induced a significant (P<0.05) rise of BGP serum level without any associated increase ofD-Pyr and GHyl, the latter also expressed as GHyl to GGHyl ratio. Urinary Pyr increased significantly after 1μg daily doses of 1,25(OH)2D3. Thus, a short course of 1μg daily doses of 1,25(OH)2D3elicits a stimulation of osteoblast activity without any enhancement ofD-Pyr, the most specific marker of osteoclast activity. The enhancement of Pyr after 1μg daily doses of 1,25(OH)2D3might be due to the activation of extraosseous metabolic pathways rather than to the activation of osteoclast.  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