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   793篇
  免费   21篇
耳鼻咽喉   10篇
儿科学   78篇
妇产科学   10篇
基础医学   74篇
口腔科学   12篇
临床医学   121篇
内科学   205篇
皮肤病学   18篇
神经病学   39篇
特种医学   5篇
外科学   99篇
综合类   13篇
一般理论   1篇
预防医学   44篇
眼科学   7篇
药学   63篇
肿瘤学   15篇
  2016年   5篇
  2015年   9篇
  2014年   15篇
  2013年   16篇
  2011年   8篇
  2010年   14篇
  2009年   26篇
  2008年   7篇
  2007年   9篇
  2006年   8篇
  2003年   9篇
  2001年   9篇
  1999年   15篇
  1998年   15篇
  1997年   38篇
  1996年   35篇
  1995年   26篇
  1994年   24篇
  1993年   22篇
  1992年   13篇
  1991年   21篇
  1990年   23篇
  1989年   13篇
  1988年   16篇
  1987年   23篇
  1986年   13篇
  1985年   13篇
  1984年   14篇
  1983年   5篇
  1982年   10篇
  1981年   9篇
  1980年   10篇
  1979年   11篇
  1978年   12篇
  1977年   8篇
  1973年   4篇
  1971年   9篇
  1970年   12篇
  1969年   10篇
  1967年   5篇
  1966年   5篇
  1960年   4篇
  1959年   13篇
  1958年   37篇
  1957年   30篇
  1956年   41篇
  1955年   25篇
  1954年   25篇
  1949年   10篇
  1948年   5篇
排序方式: 共有814条查询结果,搜索用时 15 毫秒
21.
Transseptal puncture is a standard means of catheter access to the left atrium via the venous system, but carries a risk of cardiac perforation. Stretching and increased force to traverse the septum are required with elastic, aneurysmal, or thickened interatrial tissue. We describe a technique that facilitates transseptal puncture by applying brief pulses of radiofrequency energy from a standard electrosurgical cautery generator through the needle tip.  相似文献   
22.
Coronary Venous Ablation of VT. Ventricular tachycardias in coronary artery disease arise mostly from endocardial sites. However, little is known about the site of origin in other diseases. We present the case of an incessant, adenosine-sensitive ventricular tachycardia arising from the lateral wall of the left ventricle in a patient with mildly reduced left ventricular function. Intracardiac mapping suggested an epicardial origin, and the tachycardia was successfully ablated from a coronary sinus branch. After ablation, left ventricular function returned to normal. Transcoronary venous radiofrequency catheter ablation is a new approach for the treatment of ventricular tachycardia. Its value in the management of other types of ventricular tachycardia has yet to he determined.  相似文献   
23.
Purging of autologous bone marrow (BM) grafts of children in second remission after a relapse of precursor B acute lymphoblastic leukaemia (ALL) in the BM has been carried out in our laboratory since 1987, initially by complement mediated cell lysis. This protocol was extended by performing an immunorosette depletion before lysis with complement. The aim of the present study was to assess by polymerase chain reaction the presence of residual leukaemic cells in the BM grafts before and after purging. The results were then correlated to clinical outcome. In 24/28 patients a PCR product was obtained by amplification of IgH and/or TcR junctional regions. BM before purging was available for analysis in 13 patients. We found that leukaemic cells could be detected in 8/13 (62%) of these grafts before purging . All these eight patients experienced a relapse, regardless of whether the purging procedure had been successful (defined as achievement of PCR-negativity) or not. In contrast, none of the five patients with PCR-negative grafts before purging relapsed ( P  = 0.0008). One patient died due to transplant-related toxicity. Of the remaining 23 patients, nine patients received a PCR-positive BM graft after purging. All these nine patients experienced a relapse as compared to 6/14 whose BM was PCR-negative after purging ( P  = 0.0072). Two of eight PCR-positive BM grafts could be purged to PCR-negativity. Thus, improvements both in treatment of leukaemia and in purging efficacy are still needed.  相似文献   
24.
Summary.  Assessment of impairment and function is essential in order to monitor joint status and evaluate therapeutic interventions in patients with haemophilia. The improvements in the treatment of haemophilia have required the development of more sensitive tools to detect the more minor dysfunctions that may now be apparent. This paper outlines some of the recent developments in this field. The Haemophilia Joint Health Score (HJHS) provides a systematic and robust measure of joint impairment. The MRI Scoring System has been designed to provide a comprehensive scoring system combining both progressive and additive scales. The Functional Independence Score for Haemophilia (FISH) has been developed to assess performance of functional activities and can be used in conjunction with the Haemophilia Activities List (HAL) which provides a self report measure of function. It is recommended that both measures are evaluated as these tools measure different constructs. Further refinement and testing of the psychometric properties of all of these tools is in progress. More widespread use of these tools will enable the sharing of data across the world so promoting best practice and ultimately enhancing patient care.  相似文献   
25.
Summary.  Prophylaxis is defined as primary (started before the onset of joint damage) or secondary (started after the onset of joint damage). The aim of primary prophylaxis is to prevent recurrent bleeding into joints and the development of chronic arthropathy in later life. When started early, and at most after two joint bleeds, the result is predictably excellent if there is compliance with the primary prophylaxis regimen. In order to decrease the need for central venous access devices to assure reliable venous access, a number of centres start primary prophylaxis with once weekly infusions with dose-escalation based on frequency of joint bleeding. A major unanswered question is whether primary prophylaxis can be safely discontinued in adolescents/young adults and if so, when. A promising predictor for the milder bleeding phenotype in persons with severe haemophilia is a later onset of joint bleeding. Once joint damage has occurred as a result of recurrent bleeding, secondary prophylaxis can only retard, but not prevent, ongoing joint damage. Other strategies to decrease recurrent bleeding from target joints include surgical synovectomy (ideally performed using an arthroscopic technique), radionuclide synovectomy and chemical synovectomy. These interventions have very good outcomes when performed by an experienced team. Given the very high cost of factor concentrates required for programmes of prophylaxis prospective studies that document benefits to the child and family, e.g. quality of life are to be encouraged.  相似文献   
26.
Background: Balloon aortic valvuloplasty (BAV) has been used as a bridge to surgical aortic valve replacement (SAVR) in high‐risk patients with severe symptomatic aortic stenosis (AS). Such patients are now being referred for transcatheter aortic valve implantation (TAVI). We sought to study the indications and outcomes of BAV in patients with severe AS in the pre‐TAVI era. Methods: We analyzed consecutive patients with severe AS undergoing BAV from 1990 to 2005. In these patients with no immediate surgical option, BAV was attempted to temporarily improve hemodynamics, with a goal to improve general health of the patient, and ultimately AVR. Results : A total of 99 BAVs (eight repeats, one second repeat) were performed in 90 consecutive patients. Baseline ejection fraction was ≤25% in 36 (36%) patients. The 30‐day mortality rate was 17% (n = 17). Of the 99 patients, 27 (30%) underwent AVR. Average follow‐up of patients with and without AVR was 55 ± 57 months and 16 ± 23 months, respectively. The 6‐month and 1‐year survival rates in patients who underwent AVR were 81% and 78%, respectively, versus 57% and 44% in patients who did not undergo AVR (P = 0.024). Conclusion: BAV can be used successfully to clinically improve the health of some nonsurgical patients with severe symptomatic AS, and a proportion of these patients improve to a point where AVR can be performed. Bridging to TAVI will provide further options to high‐risk patients who cannot be bridged to conventional AVR. The role of BAV in bridging to TAVI merits further study. (J Interven Cardiol 2010;23:499–508)  相似文献   
27.
Background: Besides implantation of an implantable cardioverter-defibrillator (ICD), a proportion of patients with left ventricular (LV) dysfunction due to ischemic cardiomyopathy are potential candidates for surgical LV reconstruction (Dor procedure), which changes LV ejection fraction (LVEF) considerably. In these patients, LVEF as selection criterium for ICD implantation may be difficult. This study aimed to determine the value of LVEF as criterium for ICD implantation in heart failure patients undergoing surgical LV reconstruction.
Methods: Consecutive patients with end-stage heart failure who underwent ICD implantation and LV reconstruction were evaluated. During admission, two-dimensional (2D) echocardiography (LV volumes and LVEF) was performed before surgery and was repeated at 3 months after surgery. Over a median follow-up of 18 months, the incidence of ICD therapy was evaluated.
Results: The study population consisted of 37 patients (59 ± 11 years). At baseline, mean LVEF was 23 ± 5%. Mean left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) were 175 ± 73 mL and 225 ± 88 mL, respectively. At 3-month follow-up, mean LVEF was 41 ± 9% (P < 0.0001 vs. baseline), and mean LVESV and LVEDV were 108 ± 65 mL and 176 ± 73 mL, respectively (P < 0.0001 vs. baseline). During 18-month follow-up, 12 (32%) patients had ventricular arrhythmias, resulting in appropriate ICD therapy. No significant relations existed between baseline LVEF (P = 0.77), LVEF at 3-month follow-up (P = 0.34), change in LVEF from baseline to 3-month follow-up (P = 0.28), and the occurrence of ICD therapy during 18-month follow-up.
Conclusion: LVEF before and after surgical LV reconstruction is of limited use as criterium for ICD implantation in patients with end-stage heart failure.  相似文献   
28.
The ability of the arterial baroreceptor reflex to buffer the blood pressure responses elicited by increasing the intracranial pressure (ICP) has been studied in chloralose anesthetized cats. Standardized elevations of ICP induced pressor responses of similar magnitude irrespective of whether the baroreceptor inhibitory activity was high or very low. When ICP was elevated baroreceptor activation induced a reflex reduction of flow resistance and blood pressure, but never to the same levels obtained when ICP was normal. Thus when ICP was elevated there was an upward displacement of the curve relating carotid sinus pressure to mean arterial blood pressure.  相似文献   
29.
30.
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