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   1498238篇
  免费   106352篇
  国内免费   4622篇
耳鼻咽喉   19696篇
儿科学   49665篇
妇产科学   40489篇
基础医学   220365篇
口腔科学   40765篇
临床医学   142023篇
内科学   287567篇
皮肤病学   30795篇
神经病学   127262篇
特种医学   56848篇
外国民族医学   387篇
外科学   211336篇
综合类   29585篇
现状与发展   1篇
一般理论   500篇
预防医学   121791篇
眼科学   33142篇
药学   109901篇
  6篇
中国医学   3462篇
肿瘤学   83626篇
  2021年   12415篇
  2019年   13055篇
  2018年   19159篇
  2017年   14658篇
  2016年   16561篇
  2015年   18892篇
  2014年   24768篇
  2013年   37479篇
  2012年   52579篇
  2011年   54773篇
  2010年   31846篇
  2009年   28854篇
  2008年   50460篇
  2007年   53633篇
  2006年   53614篇
  2005年   52327篇
  2004年   49909篇
  2003年   47679篇
  2002年   46401篇
  2001年   66038篇
  2000年   67747篇
  1999年   56920篇
  1998年   16094篇
  1997年   14509篇
  1996年   14053篇
  1995年   13211篇
  1994年   12325篇
  1993年   11579篇
  1992年   43567篇
  1991年   42702篇
  1990年   41297篇
  1989年   39161篇
  1988年   36141篇
  1987年   35272篇
  1986年   33592篇
  1985年   32047篇
  1984年   24150篇
  1983年   20478篇
  1982年   12354篇
  1979年   22024篇
  1978年   15715篇
  1977年   12813篇
  1976年   12515篇
  1975年   13035篇
  1974年   15785篇
  1973年   15382篇
  1972年   14263篇
  1971年   13287篇
  1970年   12244篇
  1969年   11143篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
OBJECTIVE: The aim of this study was to evaluate soft tissue image quality of a mobile cone-beam computed tomography (CBCT) scanner with an integrated flat-panel detector. STUDY DESIGN: Eight fresh human cadavers were used in this study. For evaluation of soft tissue visualization, CBCT data sets and corresponding computed tomography (CT) and magnetic resonance imaging (MRI) data sets were acquired. Evaluation was performed with the help of 10 defined cervical anatomical structures. RESULTS: The statistical analysis of the scoring results of 3 examiners revealed the CBCT images to be of inferior quality regarding the visualization of most of the predefined structures. Visualization without a significant difference was found regarding the demarcation of the vertebral bodies and the pyramidal cartilages, the arteriosclerosis of the carotids (compared with CT), and the laryngeal skeleton (compared with MRI). Regarding arteriosclerosis of the carotids compared with MRI, CBCT proved to be superior. CONCLUSIONS: The integration of a flat-panel detector improves soft tissue visualization using a mobile CBCT scanner.  相似文献   
992.
The main objective of this study was to examine the psychosocial stress model developed by Taylor and Aspinwall with emotional exhaustion as the outcome variable. Respondents, 409 men and 346 women, who had a paid job for at least 20 hours per week, completed questionnaires concerning demographic variables, personality, temperament, work pressure, workload, perceived social support, appraisal, coping, and emotional exhaustion. Structural equation analyses provided only partial support for the validity of the model. First, on theoretical and statistical grounds, one more path linking external resources to social support was added. Second, contrary to expectations, coping styles did not predict emotional exhaustion. To conclude, when coping is measured retrospectively, it does not add to our understanding of emotional exhaustion. It is suggested that future studies should be longitudinal and include objective measures of stressors and psychosocial health outcomes in addition to self‐reports. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
993.
Background It is estimated that skin cancers cost $33 million per annum to the New Zealand healthcare system. Basal cell carcinoma and squamous cell carcinoma are the commonest types of non melanoma skin cancers (NMSCs). Anecdotal evidence indicates that there has been a doubling in the incidence of NMSCs in New Zealand over the last decade. Because of the high incidence mandatory reporting of NMSCs to the National Cancer Registry is not required. This lack of accurate data has led to poor health care policies and strategies including funding and workforce planning. Aims The aims of this study are to (1) present the latest statistics on NMSCs in New Zealand, including the incidence across different regions over the last decade, patient demographics, anatomic distribution of NMSCs, incidence and sites of metastasis, and disease‐specific survival; to (2) the histopathology of NMSCs, including surgical margins, histologic grade, and perineural, lymphatic, and vascular invasion; and (3) the relative role of different faculties treating NMSCs. Method This project has been approved by the multi‐centre ethics committee. A retrospective review was conducted from patients’ histology records from public and private pathology laboratories within defined catchment areas. Criterion for analysis is a confirmed diagnosis of NMSC treated surgically. A Microsoft Access database is created that will facilitate subsequent data retrieval and analysis. Results and Conclusion It is hoped that this up‐to‐date data will form the framework for the development of sound and sustainable healthcare policies of management of NMSCs including management strategies and workforce planning, and research direction on this common disease.  相似文献   
994.
Efficacy and safety of mycophenolate mofetil (MMF) may be optimized with individualized doses based on therapeutic monitoring of its active metabolite, mycophenolic acid (MPA). In this 12-month study, 137 renal allograft recipients from 11 French centers receiving basiliximab, cyclosporine A, MMF and corticosteroids were randomized to receive either concentration-controlled doses or fixed-dose MMF. A novel Bayesian estimator of MPA AUC based on three-point sampling was used to individualize doses on posttransplant days 7 and 14 and months 1, 3 and 6. The primary endpoint was treatment failure (death, graft loss, acute rejection and MMF discontinuation). Data from 65 patients/group were analyzed. At month 12, the concentration-controlled group had fewer treatment failures (p = 0.03) and acute rejection episodes (p = 0.01) with no differences in adverse event frequency. The MMF dose was higher in the concentration-controlled group at day 14 (p < 0.0001), month 1 (p < 0.0001) and month 3 (p < 0.01), as were median AUCs on day 14 (33.7 vs. 27.1 mg*h/L; p = 0.0001) and at month 1 (45.0 vs. 30.9 mg*h/L; p < 0.0001). Therapeutic MPA monitoring using a limited sampling strategy can reduce the risk of treatment failure and acute rejection in renal allograft recipients 12 months posttransplant with no increase in adverse events.  相似文献   
995.
OBJECTIVES: To present a single centers' 7-year experience in the endovascular treatment of acute traumatic lesions of the descending thoracic aorta (ATL of the DTA). MATERIALS & METHODS: Between March 1999 and December 2006, 34 consecutive acute traumatic lesions of the descending aorta (23 men, mean age 44 years) were treated endovascularly. Stentgrafts used were TAG Excluder, Zenith TX2 and Talent. In 23 patients the Left Subclavian Artery (LSA) was covered. Mean procedural duration was 20 to 75 minutes. RESULTS: Exclusion of the rupture site was achieved in all cases with no conversion to open surgery. Overall 30-day mortality was 8.8%. Two patients died on post operative day (pod) 1 and one on pod 22 from cranial injuries. No death or neurological deficit related to the endovascular treatment was reported. Four type I endoleaks required treatment either by balloon reexpansion (n=2) or by additional stentgraft implantation (n=2). In two patients the stentgraft collapsed totally several days postoperatively. Two patients required secondary surgical procedures (iliac access complication and revascularisation of the left subclavian artery n=1). The average follow-up was 43.8 months (1-93 months). No stentgraft related abnormality has been subsequently documented. CONCLUSIONS: The endovascular treatment of ATL of the DTA may offer the best means of therapy in a polytrauma patient.  相似文献   
996.
Zusammenfassung Kniegelenkluxationen sind seltene, aber schwer wiegende Verletzungen mit z. T. erheblichen Folgen. Begleitende Nerven- und Gefäßverletzungen sind nicht selten. Bei spontaner Reposition kann das Verletzungsausmaß initial unterschätzt werden. Die primäre Diagnostik muss die neurologische Untersuchung sowie die sichere Beurteilung des Gefäßstatus einschließen. Die Sicherung der Durchblutung des betroffenen Beins steht in der Akutphase im Vordergrund, Läsionen müssen notfallmäßig operativ versorgt werden. Bei drohendem Kompartment ist eine Faszienlogenspaltung erforderlich, die Instabilität wird temporär mittels Fixateur externe transfixiert. Bei Hochrasanztraumen sind Begleitverletzungen auszuschließen, bei sedierten und beatmeten Patienten z. B. mit Spiral-CT. Sind nur die Kreuzbänder betroffen, kann ein arthroskopisch gestützter Ersatz vorgenommen werden, Transplantate werden bevorzugt von der Gegenseite entnommen. Die im angloamerikanischen Sprachraum verwendeten Allografts haben sich in unserer Region noch nicht durchgesetzt. Bei ausgedehnten Kapselläsionen und Beteiligung der Kollateralbänder sind arthroskopische Techniken nicht indiziert, es sollte offen rekonstruiert und ggf. augmentiert werden; sekundär verbliebene Instabilitäten können gezielt dem Bandersatz zugeführt werden.  相似文献   
997.
Presentations of acute appendicitis represent an ongoing challenge to surgeons. This case of retrocaecal perforated appendicitis presented clinically as a right lumbar abscess, with the concomitant new diagnosis of type 2 diabetes mellitus in a 66-year-old male. This case emphasises the importance of an abdominal CT scan in any patient presenting with unusual sepsis near the abdomen.  相似文献   
998.
In living donor liver transplantation (LDLT), obtaining the precise volume of the graft is very important to decrease volume-related postoperative complications, especially in cases with suspected small-for size grafts. We used stereology based on the Cavalieri method (CM), a new method to measure liver graft volume, and compared the results with those obtained through intraoperative measurement (IOM) and through multidetector computed tomography (MDCT) measurement. Liver volumes estimated using the 3 methods were well-correlated with each other (r(2) = 0.94 and P < 0.001 for IOM and CM; r(2) = 0.91 and P < 0.001 for IOM and MDCT, and r(2) = 0.95 and P < 0.001 for CM and MDCT); however, they were different from each other (in descending order, 908 +/- 124 cm(2), 861 +/- 121 cm(2), and 777 +/- 168 cm(2) for MDCT, CM, and IOM, respectively). Although MDCT and CM overestimated the volumes, the results of CM were almost similar to those obtained via IOM. In conclusion, our results suggest that CM measured the liver graft volume more reliably. Thus, its use, particularly in cases with suspected small-for-size graft, may prove useful.  相似文献   
999.
Heart transplantation (HTx) is a useful therapy for end‐stage Chaga? cardiomyopathy; however, Chagas reactivation remains a mayor complication. Parasitological methods offer poor diagnostic sensitivity, and use of more sensitive tools such as the Polymerase chain reaction (PCR) is usually necessary. In the present study, reactivation incidence and PCR usefulness for early reactivation diagnosis, as well as for treatment response evaluation during follow‐up, were analyzed using Strout parasite detection test, in 10 of 222 consecutive HTx patients suffering Chagas cardiomyopathy. PCR strategies targeted to minicircle sequences (kDNA, detection limit 1 parasite/ 10 mL blood) and miniexon genes (SL‐DNA, 200 parasite/10 mL) were performed to compare parasite burdens between samples. No patients received prophylactic antiprotozoal therapy (benznidazole). Five patients (50%) exhibited clinical reactivation within a mean period of 71.6 days; positive Strout results were observed in most cases presenting clinical manifestations. kDNA‐PCR was positive 38–85 days before reactivation, whereas SLDNA‐PCR became positive only 7–21 days later, revealing post‐HTx parasitic load enhancement present prior to clinical reactivation development. Reactivations were successfully treated with benznidazole and generated negative PCR results. Results observed in this study indicate the value of PCR testing for an early diagnosis of Chagas reactivation as well as for monitoring treatment efficacy.  相似文献   
1000.
Chronic, recurrent, multifocal osteomyelitis (CRMO) is an obscure disease of bone, occurring in children. It appears to be an inflammatory condition with no obvious microbiological cause. Current treatments of antibiotics and anti-inflammatory medication appear to have limited success. This case report looks at two separate cases of CRMO where partial resection of the affected bone—the clavicle—leads to complete resolution of symptoms and regrowth of the excised bone.  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