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   5513篇
  免费   358篇
  国内免费   25篇
耳鼻咽喉   45篇
儿科学   158篇
妇产科学   133篇
基础医学   778篇
口腔科学   129篇
临床医学   495篇
内科学   1582篇
皮肤病学   90篇
神经病学   304篇
特种医学   87篇
外科学   635篇
综合类   52篇
一般理论   2篇
预防医学   415篇
眼科学   121篇
药学   301篇
  1篇
中国医学   46篇
肿瘤学   522篇
  2024年   6篇
  2023年   66篇
  2022年   89篇
  2021年   190篇
  2020年   94篇
  2019年   172篇
  2018年   163篇
  2017年   121篇
  2016年   115篇
  2015年   147篇
  2014年   198篇
  2013年   285篇
  2012年   473篇
  2011年   438篇
  2010年   270篇
  2009年   205篇
  2008年   342篇
  2007年   396篇
  2006年   351篇
  2005年   363篇
  2004年   344篇
  2003年   326篇
  2002年   259篇
  2001年   25篇
  2000年   17篇
  1999年   34篇
  1998年   36篇
  1997年   26篇
  1996年   39篇
  1995年   17篇
  1994年   29篇
  1993年   17篇
  1992年   13篇
  1991年   15篇
  1990年   11篇
  1989年   7篇
  1988年   14篇
  1987年   12篇
  1986年   10篇
  1985年   15篇
  1984年   15篇
  1983年   10篇
  1982年   8篇
  1981年   15篇
  1980年   13篇
  1978年   6篇
  1977年   7篇
  1976年   10篇
  1975年   9篇
  1959年   4篇
排序方式: 共有5896条查询结果,搜索用时 15 毫秒
21.
22.
BACKGROUND: Genetic study of the RET proto-oncogene has modified the management, treatment, and prognosis of medullary thyroid carcinoma (MTC), multiple endocrine neoplasia 2A (MEN 2A), for patients with less advanced tumor stages. Classically, the diagnosis was based on an increase in basal and poststimulus peak calcitonin (bCT and pCT). Prophylactic thyroidectomy, based on results of genetic testing, may reduce recurrences in MTC. STUDY DESIGN: Of 82 MTC (MEN 2A) patients genetically diagnosed and surgically treated at our center, 22 received a prophylactic thyroidectomy (RET +, bCT and pCT with normal values and asymptomatic). We analyzed age, gender, phenotype, RET mutation, cervical ultrasound, laboratory tests (bCT, pCT, and CEA), surgery, histologic data, TNM, and followup. RESULTS: The 22 patients belonged to 8 families with MTC (MEN 2A). Mean age was 15.2 years (range 5 to 36 years). The RET mutation in 21 patients was Cys-->Tyr and in the remaining patient both in codon 634 in exon 11. The median values of bCT and pCT were 38 pg/mL (range < 15 to 75 pg/mL) and 148.5 pg/mL (range < 15 to 250 pg/mL), respectively. Total thyroidectomy was performed in 8 patients (age < or = 10 years) and associated central neck dissection in 14 patients (age> 10 years). Histologic study showed 7 C-cell hyperplasias and 15 MTCs (8 bilateral); the median size was 0.2 cm (range < 0.1 to 0.7cm); 1 patient had metastatic adenopathies. According to TNM, 7 were stage 0, 14 were stage I, and 1 was stage III. Postsurgery bCT and pCT values were normal in all patients, with a curative rate of 100%. MTC patients compared with C-cell hyperplasia patients were older on average, had higher mean bCT, mean pCT, and mean CEA. CONCLUSIONS: Prophylactic thyroidectomy based on genetic testing allows identification and treatment of patients at an early stage of the disease and decreases recurrence rates. pCT values above the upper limit of normal may be markers for the presence of MTC and should be considered in selecting operative procedures for these patients.  相似文献   
23.
Preoperative biliary drainage may improve the cytokine and acute-phase response derangements observed in patients with obstructive jaundice. We conducted a prospective longitudinal, before-after trial in our 600-bed teaching hospital. Twenty-four patients with obstructive jaundice were investigated, 11 with benign obstruction and 13 with malignant disease. Endoscopic internal biliary drainage was performed in all patients (7 by papillotomy and 17 by endoprostheses). Endotoxin, tumor necrosis factor alpha (TNF-a), interleukin-6 (IL-6), nitric oxide production, and C-reactive protein (CRP) were determined at admission and on days 2 and 7 after internal biliary drainage was accomplished. Bile cultures were obtained before and at the time of drainage. Endotoxin, IL-6, TNF-a, and CRP were significantly higher in patients with cancer. After internal drainage, endotoxin (11.4 vs. 2 EU/L; p <0.05), TNF-a (87.5 vs. 48 pg/ml; p = 0.03), and IL-6 (324 vs. 232 pg/ml; p <0.05) plasma levels decreased significantly in the early postdrainage period in patients with cancer. Endotoxin, cytokines, as well as the CRP plasma values, however, increased again on day 7 after drainage. This trend was less marked in patients with benign obstruction. Patients with positive bile cultures after drainage displayed higher levels of CRP (115 vs. 62 mg/L; p = 0.03), IL-6 (598 vs. 330 pg/ml; p = 0.04), and endotoxin (10.6 vs. 4.8 EU/L; p = 0.02) than those with negative bile cultures. Biliary tract obstruction is associated with an increase in endotoxin levels, a positive acute-phase response, and plasma cytokine elevation. After biliary drainage a transitory improvement of these alterations was observed, although values remained high 1 week postdrainage. These findings were associated with positive bile cultures.  相似文献   
24.
25.
Gallstone ileus is an uncommon type of mechanical intestinal obstruction caused by an intraluminal gallstone, and preoperative diagnosis is difficult in the Emergency department. This study is a retrospective analysis of the clinical presentation of 5 patients with gallstone ileus treated between 2000-2010. Clinical features, diagnostic testing, and surgical treatment were analyzed. Five patients were included: 2 cases showed bowel obstruction; 2 patients presented a recurrent gallstone ileus with prior surgical intervention; and one patient presented acute peritonitis due to perforation of an ileal diverticula. In all cases CT confirmed the preoperative diagnosis. In our experience, gallstone ileus may present with clinical features other than intestinal obstruction. In suspicious cases CT may be useful to decrease diagnostic delay, which is associated with more complications.  相似文献   
26.
Urculo E  Alfaro R  Arrazola M  Astudillo E  Rejas G 《Neurosurgery》2004,54(2):505-8; discussion 508-9
OBJECTIVE AND IMPORTANCE: Repeated percutaneous balloon compression for the treatment of idiopathic trigeminal neuralgia is infrequent. When a second procedure is performed, the outcome is unknown. A patient developed an isolated trochlear nerve palsy after undergoing percutaneous trigeminal ganglion balloon compression for a second time. The mechanism of diplopia and the complications associated with this technique were studied. CLINICAL PRESENTATION: The patient was a 67-year-old woman with a history of medically refractory idiopathic trigeminal neuralgia involving all three divisions of the right trigeminal nerve. INTERVENTION: Percutaneous balloon compression was performed. Despite initial total relief from pain without complications, the patient again displayed manifestations of trigeminal neuralgia 3 months after the procedure. The pain disappeared after she underwent a second balloon compression procedure, but she developed an isolated trochlear nerve palsy, which spontaneously resolved in 2 months. CONCLUSION: Isolated trochlear nerve palsy is a rare and reversible complication after percutaneous balloon compression for trigeminal neuralgia. This case illustrates that the mechanism of injury to the fourth nerve is the result of an erroneous technique: excessive penetration of the Fogarty catheter in Meckel's cave beyond the porus trigemini and compression of the cisternal segment of the trochlear nerve when the inflated balloon is pushed against the tentorium.  相似文献   
27.
Previous studies showed the involvement of brain regions associated with both spatial learning and associative learning in spatial memory extinction, although the specific role of the dorsal and ventral hippocampus and the extended hippocampal system including the mammillary body in the process is still controversial. The present study aimed to identify the involvement of the dorsal and ventral hippocampus, together with cortical regions, the amygdaloid nuclei, and the mammillary bodies in the extinction of a spatial memory task. To address these issues, quantitative cytochrome c oxidase histochemistry was applied as a metabolic brain mapping method. Rats were trained in a reference memory task using the Morris water maze, followed by an extinction procedure of the previously acquired memory task. Results show that rats learned successfully the spatial memory task as shown by the progressive decrease in measured latencies to reach the escape platform and the results obtained in the probe test. Spatial memory was subsequently extinguished as shown by the descending preference for the previously reinforced location. A control naïve group was added to ensure that brain metabolic changes were specifically related with performance in the spatial memory extinction task. Extinction of the original spatial learning task significantly modified the metabolic activity in the dorsal and ventral hippocampus, the amygdala and the mammillary bodies. Moreover, the ventral hippocampus, the lateral mammillary body and the retrosplenial cortex were differentially recruited in the spatial memory extinction task, as shown by group differences in brain metabolic networks. These findings provide new insights on the brain regions and functional brain networks underlying spatial memory, and specifically spatial memory extinction. © 2016 Wiley Periodicals, Inc.  相似文献   
28.
We retrospectively examined the association of polymorphisms in the CYP3A, CYP2J2, CYP2C8, and ABCB1 genes with pharmacokinetic (PKs) and pharmacodynamic (PDs) parameters of tacrolimus in 103 renal transplant recipients for a period of 1 year. CYP3A5 expressers had lower predose concentrations (C(0) )/dose and higher dose requirements than nonexpressers throughout the study. Among CYP3A5*1 carriers, those also carrying the CYP3A4*1B allele showed the lowest C(0) /dose, as compared with CYP3A4*1/CYP3A5*3 carriers (54.28±26.45, 59.12±24.00, 62.43±41.12, and 57.01±17.34 vs. 112.37± 76.60, 123.21±59.57, 163.34±76.23, and 183.07±107.82 at 1 week, 1 month, 5 months, and 1 year after transplantation). In addition, CYP3A4*1B/CYP3A5*1 carriers showed significantly lower dose-corrected exposure than CYP3A4*1/CYP3A5*1 carriers 1 year after transplantation (57.01±17.34 vs. 100.09±24.78; P=0.016). Only the ABCB1 TGC (3435-2677-1236) haplotype showed a consistent association with PDs (nephrotoxicity; OR=4.73; CI: 1.3-16.7; P=0.02). Our findings indicate that the CYP3A4*1B-CYP3A5*1 haplotype may have a more profound impact in tacrolimus PKs than the CYP3A5*1 allele. This study does not support a critical role of the CYP450 or ABCB1 single nucleotide polymorphisms in the occurrence of toxicity or acute rejection in renal transplant recipients treated with tacrolimus.  相似文献   
29.
30.
Background  The treatment of perforated diverticulitis is changing form the current standard of laparotomy with resection, Hartmann procedure, and colostomy to a minimally invasive technique. In patients with complicated acute diverticulitis and peritonitis without gross fecal contamination, laparoscopic peritoneal lavage, inspection of the colon, and intraoperative drain placement of the peritoneal cavity appears to alleviate morbidity and improve the outcome. In this article, we report our experience of a laparoscopic peritoneal lavage technique with delayed definitive resection when necessary. Method and materials  Records of patients who underwent intraoperative peritoneal lavage for purulent diverticulitis at the Texas Endosurgery Institute from April 1991 to September 2006 were retrospectively reviewed. Results  Forty patients were included in the study, with a male/female ratio of 26:14. The average age was 60 years. Many had associated co-morbidities. The average operating time was 62 minutes. There were no conversions to an open procedure. Apart from mild postoperative paralytic ileus in six patients and chest infections in two, there were no significant peroperative or postoperative complications. Just over 50% underwent elective interval laparoscopic sigmoid colectomy. During the mean follow-up of 96 months, none of the other patients required further surgical intervention. Conclusion  Laparoscopic lavage of the peritoneal cavity and drainage is a safe alternative to the current standard of treatment for the management of perforated diverticulitis with or without gross fecal contamination. It is associated with a decrease in the overall cost of treatment; the use of a colostomy is avoided; patient improvement is immediate; and there is a reduction in mortality and morbidity as definitive laparoscopic resection can be performed in a nonemergent fashion. Perhaps the most important benefit, other than avoiding a colostomy, is the association of fewer wound complications such as dehiscence, wound infection, and the high risk of hernia formation. Laparoscopic lavage and drainage should be considered in all patients in whom medical and/or percutaneous treatment is not feasible. It carries minimal morbidity and should be considered the standard of care.  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