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   11693篇
  免费   805篇
  国内免费   95篇
耳鼻咽喉   115篇
儿科学   257篇
妇产科学   427篇
基础医学   1536篇
口腔科学   395篇
临床医学   1080篇
内科学   2557篇
皮肤病学   198篇
神经病学   932篇
特种医学   408篇
外国民族医学   3篇
外科学   1885篇
综合类   246篇
一般理论   4篇
预防医学   617篇
眼科学   115篇
药学   616篇
  1篇
中国医学   47篇
肿瘤学   1154篇
  2023年   73篇
  2022年   126篇
  2021年   346篇
  2020年   186篇
  2019年   255篇
  2018年   317篇
  2017年   220篇
  2016年   265篇
  2015年   303篇
  2014年   388篇
  2013年   492篇
  2012年   822篇
  2011年   804篇
  2010年   444篇
  2009年   385篇
  2008年   660篇
  2007年   718篇
  2006年   598篇
  2005年   618篇
  2004年   599篇
  2003年   515篇
  2002年   513篇
  2001年   343篇
  2000年   340篇
  1999年   340篇
  1998年   110篇
  1997年   113篇
  1996年   79篇
  1995年   66篇
  1994年   77篇
  1993年   62篇
  1992年   164篇
  1991年   153篇
  1990年   123篇
  1989年   143篇
  1988年   77篇
  1987年   118篇
  1986年   80篇
  1985年   55篇
  1984年   67篇
  1983年   42篇
  1982年   26篇
  1981年   30篇
  1980年   26篇
  1979年   46篇
  1976年   30篇
  1975年   22篇
  1974年   29篇
  1972年   25篇
  1971年   21篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
81.
Wong K  Chong JL  Lo WK  Sia AT 《Anaesthesia》2000,55(3):212-216
We conducted a randomised, controlled study to investigate the effect of adding a background infusion to patient-controlled epidural analgesia for postoperative pain relief. Forty-two patients scheduled for elective lower abdominal gynaecological surgery received patient-controlled epidural analgesia postoperatively using a mixture of 0.2% ropivacaine and 2.0 microg x ml-1 fentanyl. Patients in group B (n = 20) were given a background infusion of 5 ml x h-1, whereas those in group N (n = 21) were not. There was no difference in pain scores or patient satisfaction scores between the two groups. Patients in group B had a higher total drug consumption (156.8 +/- 34.8 ml vs. 89.5 +/- 41.0 ml; p < 0.0001) and incidence of side-effects (71.4% vs. 30.0%; p = 0.007). Motor blockade during the 24-h study period was also greater in group B (median [range] area under the curve 7.5 [0.0-39.0] h vs. 3.0 [0.0-36.0] h; p = 0.035). We conclude that the addition of a background infusion to patient-controlled epidural anaesthesia is not recommended as it confers no additional benefits.  相似文献   
82.
Fan ST  Lo CM  Liu CL 《Annals of surgery》2000,231(1):126-131
OBJECTIVE: To report the authors' experience with living donor liver transplantation in adults using right lobe liver grafts, performed by a modified technique. SUMMARY BACKGROUND DATA: The initial results of seven living donor liver transplants in adults using extended right lobe grafts were satisfactory, but serious complications occurred in two donors, and six recipients required repeat laparotomy. Another 11 similar operations were performed. Further evaluation was made with the aim of improving the postoperative outcome. METHODS: From December 1996 to August 1998, 11 patients underwent living donor liver transplantation using right lobe grafts. The first four patients underwent surgery using methods previously designed and the next seven underwent a modification designed to minimize devitalized tissues on the liver transection surface, improve hepatic venous drainage, and reduce the number of hepatic duct orifices. RESULTS: There were no donor deaths. Donor complications included cholestasis (n = 1) and minor wound infection (n = 1). All the first four recipients required a repeat laparotomy for infected necrotic liver transection surface (n = 1), acute pancreatitis (n = 1), hepatic vein thrombosis (n = 1), and leakage from one of the two bilioenteric anastomoses (n = 1). The patient with hepatic vein thrombosis died. In the last seven recipients, all of whom survived the operation, one required a repeat laparotomy with the discovery of a methicillin-resistant Staphylococcus aureus culture of fibrinous exudate at the left subphrenic peritoneum, and another had right hepatic duct stump necrosis. The latter was likely related to hypovolemic shock secondary to bleeding from the right saphenous vein on removal of a hemofiltration catheter. Comparison of the incidence of repeat laparotomy between the first four and the remaining seven recipients showed a significant trend of improvement. Combining the result of the seven patients reported previously, the improvement in terms of relaparotomy rate is significant. CONCLUSION: With modification of surgical technique, living donor liver transplantation in adults using right lobe liver grafts can become a relatively safe procedure.  相似文献   
83.
NAD(P)H:quinone oxidoreductase 1 (NQO1) is a detoxification enzyme that protects cells against oxidative stress and toxic quinones. A polymorphism (C609T) in the gene produces in the heterozygous individuals (C/T) a reduction and in those homozygous for the variant allele (T/T) the abolishment of NQO1 protein activity. To assess whether NQO1 inactivating polymorphism (CT/TT) was a possible risk factor for infant acute lymphoblastic leukemia (iALL), we investigated the distribution of NQO1 genotype in 50 iALL patients, 32 with MLL gene rearrangements (MLL+) and 18 without (MLL-). As controls, 106 cases of pediatric ALL (pALL), and 147 healthy subjects were also studied. Compared to normal controls, the frequency of the low/null activity NQO1 genotypes was significantly higher in the iALL MLL- (72 vs 38%, P=0.006; odds ratio (OR) 4.22, 95% confidence interval (CI) 1.43-12.49), while no differences were observed in iALL MLL+ (44 vs 38%, P=0.553; OR 1.26, 95% CI 0.58-2.74). Similar results were observed when pALL were used as control. Our results indicate that only the iALL patients without MLL rearrangements had a significantly higher frequency of NQO1 genotypes associated with low/null activity enzyme, suggesting a possible role for NQO1 gene as an MLL-independent risk factor, in the leukemogenic process of this subtype of iALL.  相似文献   
84.
PURPOSE: Between September 1991 and May 1997, within the International Berlin-Frankfurt-Muenster Study Group (I-BFM-SG), a randomized study was performed aimed at assessing the efficacy of prolonged use of high-dose l-asparaginase (HD-l-ASP) during continuation therapy in children with standard risk (SR) acute lymphoblastic leukemia (ALL), treated with a reduced BFM-type chemotherapy. PATIENTS AND METHODS: The Italian, Dutch, and Hungarian groups participated in this study denominated IDH-ALL-91, and 494 children were enrolled. Treatment consisted of a BFM-type modified backbone with omission of the IB part in induction and elimination of two doses of anthracyclines during reinduction in both arms at the beginning of continuation therapy. Patients were randomly assigned to receive (YES-ASP) or not (NO-ASP) 20 weekly HD-l-ASP (25,000 IU/m2). RESULTS: The event-free-survival and overall survival probabilities at 10 years for the entire group were 82.5% (1.8) and 90.3% (1.3), respectively. Of the 490 patients eligible for random assignment, 355 (72.4%) were randomly assigned (178 YES-ASP and 177 NO-ASP). After a median follow-up of 9 years, the probability of disease-free survival at 10 years was 87.5% (SE, 2.5) for YES-ASP arm versus 78.7% (SE, 3.3) for NO-ASP arm (P = .03). In multivariate analysis, NO-ASP arm (P = .03), male sex (P = .004), and age older than 10 years (P = .0003) had a significantly adverse impact on outcome. CONCLUSION: In this subset of patients, selected with criteria not including monitoring of minimal residual disease, application of extended HD-l-ASP may improve prognosis, compensating reduced leukemia control that results from adoption of a reduced-intensity BFM-backbone for treatment of children with SR ALL.  相似文献   
85.
86.
87.
We sought to develop a laparoscopic technique for placement of a cervical cerclage in women with a history of failed vaginal cerclage and recurrent miscarriage. This was a case series, design classification III. The study took place at The Recurrent Miscarriage Clinic at National Women's Hospital, Auckland, New Zealand. Ten women with a history of second trimester miscarriage after failed vaginal cerclage, and 1 woman with a history of second trimester miscarriage and findings of a clinically deficient cervix were studied. A laparoscopic cervical cerclage was placed before pregnancy. No intraoperative or postoperative complications were experienced. Ten of 11 women subsequently became pregnant and all delivered live babies by cesarean section in the third trimester. Laparoscopic cervical cerclage is feasible and effective. Outcomes are good in a particularly high-risk group of women with cervical incompetence, who have had failed vaginal cerclage and have a history of recurrent pregnancy loss.  相似文献   
88.
Upper gastrointestinal bleeding from primary aortoduodenal fistula (PADF) is unusual and fatal. The etiology of PADF from tuberculous aortitis is rare. We report a 69-year-old male patient who suffered recurrent hematemesis and hematochezia with hypovolemic shock of unknown origin. Initial endoscopy failed to lead to a diagnosis. A bleeder over the third portion of the duodenum was found after the third endoscopy. Exploratory laparotomy showed a ruptured aortic pseudoaneurysm with an aortoduodenal fistula. Dacron graft repair of the aorta and simple closure of the duodenal fistula were carried out. Pathologic examination revealed tuberculous aortitis. The patient survived and was symptom-free following operation and antituberculous therapy. Review of the literature revealed that the clinical presentations in this disorder are insidious. The endoscopic findings are atypical. We conclude that so-called "herald bleeding", a history of tuberculous infection or aortic aneurysm and a high degree of suspicion are critical for successful diagnosis. Early diagnosis and surgical exploration are needed for timely and successful management.  相似文献   
89.
Neonatal and 5-year outcomes after birth at 30-34 weeks of gestation   总被引:1,自引:0,他引:1  
OBJECTIVE: To evaluate the rates of in-hospital death, neonatal complications, and 5-year outcomes of infants born at 30-34 weeks of gestation. METHODS: In nine regions of France, all 2,020 stillbirths and live births at 30, 31, and 32 weeks in 1997 and all 457 births at 33 and 34 weeks in April and October 1997 were recorded. Survivors were evaluated at 5 years of age. RESULTS: Increasing gestational age from 30 to 34 weeks was associated with progressive decreases in in-hospital mortality (from 8.1% to 0.4%) and neonatal complications (respiratory distress syndrome, 43.8% to 2.6%; maternofetal infections, 7.2% to 2.6%; and severe white matter injury, 5.5% to 1.3%). Although infants at 33 and 34 weeks of gestation rarely experienced necrotizing enterocolitis, bronchopulmonary dysplasia, or nosocomial infections, they still required endotracheal ventilation, antibiotics, or parenteral nutrition. At 5 years of age, older gestational age was associated with significant decreases in rates of cerebral palsy (6.3% at 30 weeks and 0.7% at 34 weeks) and mild to severe cognitive impairments (35.3% at 30 weeks and 23.9% at 34 weeks). In singletons, preterm rupture of membranes or preterm labor carried an increased risk of cerebral palsy but not of cognitive impairment. CONCLUSION: Neonates born at 30-34 weeks experienced substantial morbidity and often required admission to neonatal intensive care units. These outcomes suggest that prolonging pregnancies beyond 34 weeks may be desirable whenever possible. Infants born at 30-34 weeks should be carefully monitored to ensure prompt detection and management of neurodevelopmental impairment.  相似文献   
90.
To date, the number of cases reported after exposure to mifepristone alone in early pregnancy is limited. In 24 cases, only 1 observation of fetal malformation associated with mifepristone has previously been reported. We report a case of amniotic band syndrome with limb amputation after exposure to mifepristone in early pregnancy. This association raises the question of a possible causal relationship.  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