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   11683篇
  免费   711篇
  国内免费   73篇
耳鼻咽喉   170篇
儿科学   412篇
妇产科学   398篇
基础医学   1053篇
口腔科学   362篇
临床医学   992篇
内科学   2508篇
皮肤病学   193篇
神经病学   660篇
特种医学   405篇
外科学   2232篇
综合类   376篇
现状与发展   1篇
一般理论   12篇
预防医学   746篇
眼科学   260篇
药学   924篇
中国医学   75篇
肿瘤学   688篇
  2023年   119篇
  2022年   351篇
  2021年   543篇
  2020年   303篇
  2019年   387篇
  2018年   489篇
  2017年   278篇
  2016年   380篇
  2015年   390篇
  2014年   520篇
  2013年   660篇
  2012年   919篇
  2011年   883篇
  2010年   504篇
  2009年   386篇
  2008年   624篇
  2007年   694篇
  2006年   643篇
  2005年   559篇
  2004年   492篇
  2003年   411篇
  2002年   394篇
  2001年   138篇
  2000年   123篇
  1999年   106篇
  1998年   70篇
  1997年   58篇
  1996年   45篇
  1995年   40篇
  1994年   41篇
  1993年   28篇
  1992年   94篇
  1991年   57篇
  1990年   72篇
  1989年   63篇
  1988年   49篇
  1987年   53篇
  1986年   25篇
  1985年   42篇
  1984年   29篇
  1983年   37篇
  1982年   20篇
  1980年   19篇
  1979年   33篇
  1978年   20篇
  1977年   26篇
  1976年   18篇
  1974年   34篇
  1973年   32篇
  1972年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Abstract Objective: This study assesses surgical procedures, operative outcome, and early and intermediate‐term results of infective valve endocarditis in children with congenital heart disease. Methods: Seven consecutive children (five females, two males; mean age, 10.8 years) who underwent surgery for infective valve endocarditis between 2006 and 2010 were included in the study. The aortic and mitral valves were affected in two and tricuspid in five patients. Indications for operation included cardiac failure due to atrioventricular septal rupture, severe tricuspid valve insufficiency, and septic embolization in one, moderate valvular dysfunction with vegetations in three (two tricuspid, one mitral), and severe valvular dysfunction with vegetations in the other three patients (two tricuspid, one mitral). The pathological microorganism was identified in five patients. Tricuspid valve repair was performed with ventricular septal defect (VSD) closure in five patients. Two patients required mitral valve repair including one with additional aortic valve replacement. Results: There were no operative deaths. Actuarial freedom from recurrent infection at one and three years was 100%. Early echocardiographic follow‐up showed four patients to have mild atrioventricular valve regurgitation (three tricuspid and one mitral) and three had no valvular regurgitation. No leakage from the VSD closure or any valvular stenosis was detected postoperatively. Conclusions: Mitral and tricuspid valve repairs can be performed with low morbidity/mortality rates and satisfactory intermediate‐term results in children with infective valve endocarditis . (J Card Surg 2012;27:93‐98)  相似文献   
102.
103.

Summary

The influences of age, physical activity, and body anthropometry on calcaneal speed of sound are different among young adults, middle-aged, and elderly men.

Introduction

Quantitative ultrasound assessment of bone health status is much needed for developing countries in the screening of osteoporosis, but further studies on the factors that influence the quantitative ultrasound indices are required.

Objectives

The present study examined the influence of age, lifestyle factors, and body anthropometry on calcaneal speed of sound (SOS) in a group of Malaysian men of diverse age range.

Subjects and methods

A cross-sectional study was conducted, and data from 687 eligible males were used for analysis. They answered a detailed questionnaire on their physical activity status, and their anthropometric measurements were taken. Their calcaneal SOS values were evaluated using the CM-200 sonometer (Furuno, Nishinomiya City, Japan).

Results

Subjects with higher body mass index (BMI) had higher calcaneal SOS values albeit significant difference was only found in the elderly subjects (p?<?0.05). Sedentary subjects had lower calcaneal SOS values than physically active subjects, but significant difference was only found in the middle-aged subjects (p?<?0.05). Calcaneal SOS was significantly (p?<?0.05) correlated with age in young men; height, BMI, and physical activity score in middle-aged men; height and physical activity score in elderly men; and age and physical activity score for overall subjects. In a multivariate regression model, significant (p?<?0.05) predictors for calcaneal SOS included age for young men; physical activity, BMI, body fat percentage, and height for middle-aged men; height for elderly men; and age, height, physical activity, weight, and body fat percentage for overall subjects.

Conclusion

Age, body anthropometry, and physical activity level have significant effects on the calcaneal SOS value in men.  相似文献   
104.
Introduction

Tuberculous spondylitis (TBS) is the most common form of extra-pulmonary tuberculosis. The mainstay of TBS management is anti-tuberculous chemotherapy. Most of the patients with TBS are treated conservatively; however in some patients surgery is indicated. Most common indications for surgery include neurological deficit, deformity, instability, large abscesses and necrotic tissue mass or inadequate response to anti-tuberculous chemotherapy. The most common form of TBS involves a single motion segment of spine (two adjoining vertebrae and their intervening disc). Sometimes TBS involves more than two adjoining vertebrae, when it is called multilevel TBS. Indications for correct surgical management of multilevel TBS is not clear from literature.

Materials and methods

We have retrospectively reviewed 87 patients operated in 10 years for multilevel TBS involving the thoracolumbar spine at our spine unit. Two types of surgeries were performed on these patients. In 57 patients, modified Hong Kong operation was performed with radical debridement, strut grafting and anterior instrumentation. In 30 patients this operation was combined with pedicle screw fixation with or without correction of kyphosis by osteotomy. Patients were followed up for correction of kyphosis, improvement in neurological deficit, pain and function. Complications were noted. On long-term follow-up (average 64 months), there was 9.34 % improvement in kyphosis angle in the modified Hong Kong group and 47.58 % improvement in the group with pedicle screw fixation and osteotomy in addition to anterior surgery (p < 0.001). Seven patients had implant failures and revision surgeries in the modified Hong Kong group. Neurological improvement, pain relief and functional outcome were the same in both groups.

Conclusion

We conclude that pedicle screw fixation with or without a correcting osteotomy should be added in all patients with multilevel thoracolumbar tuberculous spondylitis undergoing radical debridement and anterior column reconstruction.

  相似文献   
105.

Aim

We analyzed the outcomes and effectiveness of surgical treatments and clinical manifestations of splenic hydatid cysts.

Patients and Methods

Between 2000 and 2011, we retrospectively reviewed the cases of 11 patients who were operated on for a splenic hydatid cyst. The demographic features, medical history, physical examinations, biochemical and serological tests, imaging modalities, and surgical treatment of the patients were noted.

Results

The mean patient age was 36.45?years (range, 20?C66?years). While isolated splenic hydatid disease was present in five patients, other abdominal hydatid cysts were accompanied by a splenic hydatid cyst in six patients. Left upper abdominal pain was present in seven (64%) patients, whereas four (36%) patients were asymptomatic. Eight patients (72.72%) had undergone a total splenectomy and three (27.28%) had undergone spleen-preserving surgery. Postoperative complications developed in four (36%) patients at 5?C15?days postoperatively.

Conclusion

Management of a splenic hydatid cyst is not consensual. Total splenectomy is optimal because it provides definitive treatment. However, spleen-preserving surgery is the preferred treatment in selected patients. The choice of technique depends on the localization, number, and size of hydatid cysts, and the absence or presence of other hydatic organ cysts.  相似文献   
106.
BACKGROUND: Gender-related differences in morbidity and mortality are well described for coronary artery bypass grafting but are not well understood for combined valve and bypass surgery. METHODS: We reviewed retrospectively the morbidity and mortality of 1570 consecutive patients who underwent combined valve and bypass procedures at the Toronto General Hospital between January 1990 and October 2000. RESULTS: There were 1073 men (68%) and 497 women (32%). The mean ages (+/- 1 SD) of women and men were 69 +/- 9 and 68 +/- 9 years, respectively (P =.02). Of the 1570 total patients, 973 patients (62%) underwent aortic valve and coronary bypass surgery, 481 patients (31%) had mitral valve and coronary bypass operations, and 116 (7%) patients had double or triple valve and coronary bypass operations. Preoperative hypertension (P =.002), diabetes (P =.001), and atrial fibrillation (P =.001) were seen more frequently in women. Body surface area was significantly lower in women (P =.0001). At presentation, more women were in congestive heart failure (69% vs 58%, P =.001) and in New York Heart Association functional class III or IV (25% vs 19%, P =.001). Although there was no difference in the number of women with three or more diseased vessels (32% vs 38%), only 35% of women received three or more grafts compared with 44% of men (P =.001). The use of left internal thoracic grafts, although uncommon in the whole study population (36%), was less common in women than in men (26% vs 41%, P =.001). Multivariable logistic analyses for morbidity and mortality showed female gender to be an independent risk factor. Mitral valve replacement, age, left ventricular dysfunction, New York Heart Association classes III and IV, and association of tricuspid valve disease, diabetes, peripheral vascular disease, and preoperative renal failure were found to be independent risk factors for mortality. CONCLUSION: Female gender is an independent risk factor for combined morbidity and mortality during and after combined valve and coronary bypass surgery. As with isolated coronary artery bypass grafting, women undergoing combined procedures have more premorbid conditions, are more often in heart failure, had an equal incidence of triple vessel disease but received fewer grafts than men, and, therefore, were more frequently incompletely revascularized.  相似文献   
107.
T-cell mediated immune responses play a critical role in chronic allograft dysfunction. The complex nature of allograft rejection, particularly with respect to the vast repertoire of alloantigens and their mode of recognition by T cells, presents a major challenge for the design of well-controlled studies into the immunobiology of chronic rejection. The purpose of this study was to develop a rat model with restricted antigenic specificity that develops chronic rejection without any immunologic manipulation to study the T-cell response. PVG.1U allogeneic hearts disparate for one single class I antigen, RT.1A(u), were transplanted into PVG.R8 rat recipients. Grafts from PVG.R8 were used as syngeneic controls. Chronic rejection was studied by histological analysis of the grafted hearts at various time points posttransplantation (20-100 days). Donor specific alloreactive response was studied in a mixed lymphocyte reaction assay. All allografts survived more than 90 days and showed extensive evidence of chronic rejection, which was characterized by interstitial fibrosis, vasculitis, and occlusive myointimal thickening. Chronic rejection was evident by day 20 and most extensive by day 100 posttransplantation. In marked contrast, syngeneic grafts remained free of chronic lesions. Lymphocytes harvested from graft recipients showed a more vigorous proliferative response to allogeneic splenocytes as compared with that of lymphocytes from nai;ve animals. The proliferative response was primarily mediated by CD4(+) T cells recognizing the RT1.A(a) molecule via the indirect pathway. A single class I disparity in this model generates chronic rejection associated with potent CD4(+) T-cell responses induced by the indirect recognition pathway. The use of this antigenically restricted model may facilitate the design of well-controlled studies for the characterization of immune mechanisms responsible for chronic rejection.  相似文献   
108.
Hepatitis C (HCV)-positive liver grafts have been increasingly used in patients with decompensated liver disease from HCV because of critical shortage of available organs. Fifty-nine recipients of HCV-positive grafts were matched to patients who received HCV-negative grafts. All recipients were transplanted for HCV liver disease. Matching variables were (1) status, (2) pre-transplant creatinine, (3) recipient age, (4) donor age, (5) warm ischemia time, and (6) year of transplantation. Both unmatched and matched analyses were performed on patient survival, graft survival, and time to HCV recurrence. There was no significant statistical difference in patient, graft, or HCV recurrence-free survival between recipients of HCV-positive and HCV-negative grafts with matched and unmatched analyses (p > 0.05). The 3-year estimates of HCV disease-free survival were 12% (+/- 9%) and 19% (+/- 7%) using HCV-positive and -negative grafts, respectively. The use of HCV-positive grafts in recipients with HCV does not appear to affect patient survival, graft survival, or HCV recurrence when compared with the use of HCV-negative grafts. Our results suggest that HCV-positive grafts can be used in a HCV liver transplant recipient.  相似文献   
109.
Most entities in and around the anterior two-thirds of the supratentorial ventricles can be reached via transcortical or transcallosal approach. This study examined the effect of surgical approach on the postoperative neurological outcome. Thirty-eight patients with intra- and periventricular supratentorial lesions were operated on by either frontal transcortical or anterior transcallosal approach. Postoperative diencephalic damage occurred in 22% of patients in the transcortical group and in 36% in the transcallosal group; transient mutism was virtually equivalent in the two groups. Postoperative epilepsy (26%) and subdural fluid collections (30%) occurred only in the transcortical group. The incidence of postoperative hemiparesis was higher in the transcallosal group. There was a high correlation between postoperative Glasgow Outcome Score of 5 and preoperative severity of neurological disease but no correlation between postoperative Glasgow Outcome Score of 5 and location of the lesion or between postoperative clinical course and surgical approach. Surgical outcome of ventricle-associated lesions depends mainly on the severity of preoperative symptoms and not on surgical approach. Additionally, the incidence of postoperative seizures and subdural fluid collections after transcortical surgery is high.  相似文献   
110.
OBJECTIVE: To determine whether antisepsis with povidone-iodine solution applied at the external urethral meatus confers protection against infective complications following transurethral resection of the prostate (TURP) and compare that with antibacterial prophylaxis. METHODS: A total of 167 patients with sterile urine undergoing TURP for benign prostatic hyperplasia (BPH) were prospectively randomized into three groups. Group A, had gauze soaked in saline applied at the urethral meatus (control group). In group B, the gauze was soaked in povidone-iodine instead of saline and group C had a single 1 g i.v. injection of cephradine at induction of anaesthesia with no treatment for the meatus. Bacteraemia, post-operative bacteriuria and other infective complications were compared in the three groups. Associations of bacteriuria at catheter removal and intra-operative bacteraemia with infective complications and with long term bacteriuria were also studied. RESULTS: Bacteriuria rate at catheter removal was not significantly different in the three groups. However, intraoperative bacteraemia and bacterial growth at the external urethral meatus was significantly lower in group C. Bacteriuria at catheter removal was significantly associated with bacterial growth at the meatus but not with long term bacteriuria at 3 months. Bacteriuria at catheter removal could not accurately predict infective complications. CONCLUSION: Post-TURP bacteriuria appears to be preceded by bacterial growth at the external urethral meatus. Antisepsis with povidone-iodine solution application at the meatus does not confer adequate protection against meatal bacterial growth as that obtained by prophylactic antibacterials. Nonetheless, neither antibacterial prophylaxis nor local antisepsis could reduce bacteriuria rate in this study.  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