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   1531篇
  免费   55篇
  国内免费   11篇
耳鼻咽喉   28篇
儿科学   39篇
妇产科学   22篇
基础医学   133篇
口腔科学   44篇
临床医学   110篇
内科学   336篇
皮肤病学   19篇
神经病学   76篇
特种医学   99篇
外科学   333篇
综合类   9篇
一般理论   1篇
预防医学   80篇
眼科学   14篇
药学   125篇
中国医学   8篇
肿瘤学   121篇
  2023年   6篇
  2022年   19篇
  2021年   35篇
  2020年   18篇
  2019年   32篇
  2018年   43篇
  2017年   31篇
  2016年   33篇
  2015年   38篇
  2014年   42篇
  2013年   86篇
  2012年   112篇
  2011年   138篇
  2010年   87篇
  2009年   100篇
  2008年   155篇
  2007年   145篇
  2006年   100篇
  2005年   84篇
  2004年   72篇
  2003年   88篇
  2002年   55篇
  2001年   7篇
  2000年   6篇
  1999年   8篇
  1998年   10篇
  1997年   6篇
  1996年   10篇
  1995年   6篇
  1994年   4篇
  1992年   2篇
  1990年   3篇
  1989年   3篇
  1988年   1篇
  1987年   2篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
  1975年   1篇
排序方式: 共有1597条查询结果,搜索用时 62 毫秒
991.

Background  

Acute small bowel obstruction (SBO) is a relatively common cause of emergency hospital admission, most frequently due to postoperative adhesions. With increased experience and technical advances in laparoscopic surgery, the laparoscopic management of acute SBO has become feasible and potentially superior to the open approach. This retrospective study presents the authors’ experience with laparoscopic treatment of SBO over a 6-year period to assess the feasibility, efficacy, and clinical outcome of this therapeutic method and to present the author’s methodology.  相似文献   
992.
Purpose:?Experimental studies suggest that the FAS/APO-1/CD95 (cytokine receptor protein TNF-receptor superfamily, member 6) cell surface molecule is involved in the apoptotic effect of radiotherapy. In this study we investigated the role of amifostine in protecting the CD95+ (CD: cluster of differentiation) lymphocytic subpopulation in patients with head and neck cancer undergoing radiotherapy.

Materials and methods:?Using flow-cytometry we examined the expression of FAS/CD95 antigen on CD4+ (helper/inducer T cells), CD8+ (suppressor/cytotoxic T cells) and CD56+ (NK, natural killer) T-lymphocytes of 28 patients with head and neck cancer undergoing radiotherapy (with and without amifostine).

Results:?The numbers of peripheral blood lymphocytes were significantly reduced after treatment from (mean value ± STD error) 1477 ± 129 to 1015 ± 77 for T lymphocytes, 700 ± 70 to 454 ± 38 for CD4, 449 ± 46 to 296 ± 34 for CD8 and, 140 ± 18 to 118 ± 13 for NK, before and after treatment, respectively. CD95 expressing lymphocytes showed a faster recovery rate in patients receiving amifostine. CD95 expressing CD56 lymphocytes increased during radiotherapy in patients receiving daily cytoprotection with amifostine to values higher than the pre-treatment levels (p = 0.004).

Conclusion:?It is suggested that amifostine enhances recovery of T- and NK-lymphocyte subpopulations expressing the CD95 antigen in head-neck cancer patients undergoing RT and may enhance the efficacy of the later by interfering FAS-related immunological pathways.  相似文献   
993.
Complications of laparoscopic adjustable gastric banding occur in 10–20% of patients. However, hepatobiliary complications of this procedure are very rare. We report a unique case of gastric band misplacement around the hepato-duodenal ligament. The patient developed obstructive jaundice several months after the gastric band placement and suffered recurrent episodes of obstructive jaundice and cholangitis that were initially erroneously attributed to fatty infiltration of the liver. Further diagnostic work-up demonstrated the presence of the gastric band in the hepatic hilum. Exploratory laparotomy confirmed the diagnosis, and the band was removed. Jaundice reversed and hepatic function was restored following removal of the occluding band.  相似文献   
994.
Objectives To report the long-term results and evaluate the effectiveness of the dorsal on-lay preputial graft urethroplasty in patients suffering from anterior urethra strictures. Methods A total of 21 male patients, mean age 46.3 years (range 17–67), with anterior urethral strictures, underwent the dorsal on-lay preputial graft urethroplasty during the last 8 years, from October 1997 to September 2005. Strictures were located in bulbar urethra in 16 patients and in penile urethra in the remaining 5. The aetiology the stricture was traumatic injury of the anterior urethra in 12 patients and iatrogenic in 9 patients.␣A direct vision dorsal urethrotomy and the insertion of an urethral Foley catheter right before the procedure, facilitated the corpus spongiosum dissection and the preparation for urethroplasty. A voiding cystogram was performed on the day of urethral catheter removal to exclude extravasation and estimate the postoperative result. Results Mean follow-up time has been 49.9 months (range 6–95) and the outcome was favourable in 15 patients (71.43%). There were 3 recurrences in penile urethra strictures managed conservatively and three in bulbar urethroplasties, treated with internal urethrotomy followed by urethral dilatations. Conclusion Our results indicate that dorsal on-lay urethroplasty using preputial graft is an easy to learn and perform procedure, and offers the patient durable␣results with rather minimal complications.  相似文献   
995.
The prevalence of vesicoureteral reflux (VUR), although reported to be low in the general population, is high in children with urinary tract infection (UTI), first degree relatives of patients with known VUR and children with antenatal hydronephrosis. In addition, it has been shown that VUR and UTIs are associated with renal scarring, predisposing to serious long-term complications, i.e., hypertension, chronic renal insufficiency and complications of pregnancy. Therefore, diagnostic imaging for the detection of VUR in the high-risk groups of children has been a standard practice. However, none of these associations has been validated with controlled studies, and recently the value of identifying VUR after a symptomatic UTI has been questioned. In addition, several studies have shown that renal damage may occur in the absence of VUR. On the other hand, some patients, mainly males, may have primary renal damage, associated with high-grade VUR, without UTI. Recently, increasing skepticism has been noted concerning how and for whom it is important to investigate for VUR. It has been suggested that the absence of renal lesions after the first UTI in children may rule out VUR of clinical significance and reinforces the redundancy of invasive diagnostic techniques. Therefore, the priority of imaging strategies should focus on early identification of renal lesions to prevent further deterioration.  相似文献   
996.
Osteoprotegerin (OPG), receptor activator of the nuclear factor κB ligand (RANKL) and fibroblast growth factor-23 (FGF-23) play a central role in renal osteodystrophy. We evaluated OPG/RANKL and FGF-23 levels in 51 children with chronic kidney disease (CKD) [n = 26 stage 3 or 4 (CKD3–4) and n = 25 stage 5 (CKD5)] and 61 controls. Any possible association with intact parathyroid hormone (iPTH) and bone turnover markers was also investigated. The OPG levels were lower in the CKD3–4 group (p < 0.001) and higher in the CKD5 group (p < 0.01) than in the controls, while RANKL levels did not differ. The FGF-23 levels were higher in both patient groups (p < 0.0001), while the levels of phosphate and iPTH were higher only in the CKD5 group (p < 0.0001). There were independent positive correlations between OPG and RANKL (β = 0.297, p < 0.01) and FGF-23 (β = 0.352, p < 0.05) and a negative correlation with the bone resorption marker TRAP5b (β = −0.519, p < 0.001). OPG was positively correlated with iPTH (R = 0.391, p < 0.01). An independent positive correlation between FGF-23 and phosphate (β = 0.368, p < 0.05) or iPTH (β = 0.812, p < 0.0001) was noted. In conclusion, we found that higher OPG levels in patients with CKD stage 5 correlated with the levels of RANKL, FGF-23, iPTH, and TRAP5b. These findings may reflect a compensatory mechanism to the negative balance of bone turnover. High FGF-23 levels in early CKD stages may indicate the need for intervention to manage serum phosphate (Pi) levels.  相似文献   
997.
The Maisonneuve fracture is considered by many to be one of the most unstable ankle injuries. We report a rare injury involving fracture of the proximal fibula in association with a posterior malleolar fracture and disruption of the anterior-inferior tibiofibular ligament, without disruption of the deltoid ligament or fracture of the medial malleolus. This report of a diagnostically challenging case highlights the importance of timely clinical and radiographic reassessment of a patient who fails to improve with initial therapy, and describes the clinical and diagnostic imaging findings of an unusual ankle injury.  相似文献   
998.
Background: Inhibition of N-methyl-d-aspartate (NMDA) receptors by anesthetic gases and vapors may play an important role in anesthesia and neuroprotection. However, the site of action of these agents on the NMDA receptor is unknown. The authors show that xenon and isoflurane compete for the binding of the coagonist glycine on the NMDA receptor NR1 subunit.

Methods: Using a novel application of grand canonical Monte Carlo simulations, the authors predict the binding site of xenon on NMDA receptors. They test this prediction using electrophysiology on recombinant NMDA receptors.

Results: The authors' modeling predicts that xenon binds at the glycine site of the NMDA receptor. The authors show that inhibition of NMDA receptors by xenon and isoflurane increases as glycine concentration is decreased, consistent with the prediction of competitive inhibition at the glycine site. Lineweaver-Burk analysis shows that isoflurane inhibition seems purely competitive with glycine, but for xenon, there is an additional component of noncompetitive inhibition. The loss of inhibitory effect of xenon and isoflurane in mutant NR1(F639A)/NR2A receptors is explained by increased glycine affinity of the mutant receptors, and inhibition is restored at low glycine concentrations.  相似文献   

999.

OBJECTIVE

To investigate the tissue distribution of ischaemia in human detrusor in patients with bladder outlet obstruction (BOO) and to correlate the results with clinical variables, as clinical BOO is a common problem in ageing men and ischaemia might be important in detrusor dysfunction.

PATIENTS AND METHODS

From September 2004 to October 2006, 70 patients were recruited, comprising 60 scheduled for surgery to treat benign prostatic hyperplasia (the study group) and 10 as controls. Detrusor tissue was retrieved and stained for hypoxia‐inducible factor (HIF)‐1α, a cellular marker of hypoxia.

RESULTS

The mean (sd ) total number of cells immunoreactive to HIF‐1α in the study group was 93.3 (48.09), and in the specimens from the control group only few rare cells showed weak immunoreactivity to HIF‐1α (0–2). Positive cells were in different proportions between muscle bundles and submucosa, expressed mainly in stromal cells. The urothelium and detrusor muscle showed no immunoreactivity to HIF‐1α. There was strong immunoreactivity in patients with prolonged BOO (<10 years), declining thereafter, and in those patients with urinary retention.

CONCLUSIONS

The urothelium and detrusor seem to be more resistant to hypoxic stress, while stromal cells perceive low oxygen tension. The bladder response to chronic hypoxia through HIF‐1α expression is limited in time and might depend on the functional status of the detrusor.  相似文献   
1000.
Safety of Repair for Severe Duodenal Injuries   总被引:2,自引:0,他引:2  
Background There is ongoing debate about the management of severe duodenal injuries (SDIs), and earlier studies have recommended pyloric exclusion. The objective of this study was to compare primary repair with pyloric exclusion to examine if primary repair can be safely used in SDIs. Methods The medical records of 193 consecutive patients who were admitted between August 1992 and January 2004 with duodenal injuries were reviewed. After excluding early deaths (n = 50), low-grade duodenal injuries (n = 81), and pancreatoduodenectomies for catastrophic trauma (n = 12), a total of 50 patients with SDIs (grade III, IV, or V) were analyzed. Primary repair (PR—simple duodenorrhaphy or resection and primary anastomosis) was performed in 34 (68%) and pyloric exclusion (PE) in 16 (32%). Characteristics and outcomes of these two groups were compared. Results PE and PR patients were similar for age, injury severity score, abdominal abbreviated injury score, physiologic status on admission, time to operation, and most abdominal organs injured. PE patients had more pancreatic injuries (63% vs. 24%, p < 0.01), a higher frequency of injuries to the first and second part of the duodenum (79% vs. 42%, p = 0.02), and a nonsignificant trend toward more grade IV and V injuries (37% vs. 18%, p = 0.11). There was no difference in morbidity (including complications specific to the duodenal repair), mortality, and intensive care unit and hospital length of stay between the two groups. Conclusions Pyloric exclusion is not necessary for all patients with SDIs, as previously suggested. Selected SDI patients can be safely managed by simple primary repair.  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