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   5266篇
  免费   608篇
  国内免费   17篇
耳鼻咽喉   74篇
儿科学   228篇
妇产科学   148篇
基础医学   804篇
口腔科学   83篇
临床医学   574篇
内科学   1162篇
皮肤病学   35篇
神经病学   543篇
特种医学   327篇
外科学   613篇
综合类   107篇
一般理论   4篇
预防医学   572篇
眼科学   37篇
药学   274篇
中国医学   7篇
肿瘤学   299篇
  2022年   36篇
  2021年   68篇
  2020年   45篇
  2019年   54篇
  2018年   96篇
  2017年   85篇
  2016年   93篇
  2015年   96篇
  2014年   129篇
  2013年   179篇
  2012年   214篇
  2011年   230篇
  2010年   180篇
  2009年   155篇
  2008年   192篇
  2007年   225篇
  2006年   207篇
  2005年   184篇
  2004年   203篇
  2003年   205篇
  2002年   196篇
  2001年   161篇
  2000年   153篇
  1999年   164篇
  1998年   121篇
  1997年   102篇
  1996年   115篇
  1995年   94篇
  1994年   77篇
  1993年   74篇
  1992年   141篇
  1991年   130篇
  1990年   139篇
  1989年   127篇
  1988年   124篇
  1987年   100篇
  1986年   92篇
  1985年   82篇
  1984年   81篇
  1983年   70篇
  1982年   53篇
  1981年   42篇
  1980年   42篇
  1979年   42篇
  1978年   36篇
  1977年   46篇
  1976年   49篇
  1974年   34篇
  1973年   35篇
  1971年   34篇
排序方式: 共有5891条查询结果,搜索用时 23 毫秒
91.
We assessed the long-term patency of kissing stent reconstruction of the aortoiliac bifurcation and identified variables that may influence it. We retrospectively reviewed our experience with stent-reconstruction procedures of the aortoiliac bifurcation from January 1998 through June 2005. The impact of demographic variables, vascular risk factors, disease location and characteristics, stent material and design, and stenting configuration on stent patency was assessed using univariate and multivariate analysis. In particular, we evaluated the effect of geometric mismatch between the protruding segment of the stents and the distal aortic lumen. Sixty-six patients underwent aortobi-iliac stent reconstruction. Indications were bifurcation or bilateral proximal iliac disease in 52 patients and unilateral ostial disease requiring contralateral protection in 14 patients. Limited disease (TASC A and B) was present in 40 limbs in 19 patients; extensive/diffuse disease (TASC C and D) was present in 78 limbs in 47 patients. Complete occlusions were present in 37 limbs in 28 patients (bilateral in nine patients). Self-expanding stents were used in 56 procedures and balloon-expandable stents in 10. Crossing configuration was used in 43 procedures, while abutting configuration was used in 23 procedures. Technical success was achieved in 62 patients (94%), with all four failures due to inability to cross a chronically occluded limb. Three of these patients underwent aortomono-iliac stenting with a crossover femoral-femoral bypass graft, with the remaining one opting for no further interventions. Median combined follow-up was 37 +/- 27 months (range 0-102). Hemodynamically significant restenosis developed in nine patients (14%). The management of restenosis was endovascular in eight patients and was successful in all (balloon dilation in four, restenting in three, thrombolysis and stenting in one) and operative in one patient who developed aortic occlusion and underwent aortobifemoral grafting. Survival table analysis showed primary and assisted patency rates at 4 years of 81% and 94%, respectively. The mortality rate during follow-up was 19 (cardiac cause in eight, pulmonary cause in three, and malignancy in five). Univariate analysis showed radial mismatch (aortic lumen dead space around the protruding segment of the stents), female gender, prior occlusion, and residual stenosis to be significant predictors of restenosis. Multivariate logistic regression analysis showed radial mismatch to be the only significant determinant of restenosis, although the statistical power of the model was limited by the small number of restenoses. Stent reconstruction of the aortoiliac bifurcation for occlusive disease is effective and durable, even with complex aortoiliac disease and long segment occlusions. Most restenoses are amenable to endovascular treatment, with excellent long-term assisted patency. Geometric variables related to individual aortic anatomy and disease pattern (patient-dependent) and stenting configuration (operator-dependent) may have an impact on long-term patency.  相似文献   
92.
BACKGROUND: Blood product utilization is an important issue in health care, given the frequent shortages in hospitals and the societal burden required to maintain the supply. Therefore, we retrospectively audited our blunt spleen/liver trauma experience to determine the percentage of cross-matched blood that was transfused to see whether more stringent typing criteria should be applied. METHODS: A retrospective analysis of a recent 7-year experience with nonoperative management in patients with blunt spleen or liver injury was performed. Demographics, packed red blood cells prepared by cross-match, and transfusions were measured. Unmatched, O-type blood given in the trauma bay was excluded. Patients undergoing laparotomy for solid organ injury were excluded. Data are expressed as mean +/- standard deviation. RESULTS: During the study period, 130 patients were nonoperatively managed for spleen and/or liver injury. Mean age was 8.7 +/- 4.6 years, and 62% were male. The mean grade of injury was 2.4 +/- 0.9. A total of 187 units of packed red blood cells was ordered in 60 patients. A total of 46.5 units was administered to 22 patients, revealing a 24.9% transfusion rate for the units ordered in 36.7% of the patients for whom it was ordered. When patients with other major injuries and those with ongoing bleeding requiring an operation or who clinically required blood on presentation were excluded, there were 80 patients. In this stable population, 104 units of PRBCs were ordered for 29 patients. A total of 18 units was then transfused in 5 patients, for a 17.3% transfusion rate for the units orders in 17.2% of the patients for whom it was ordered. None of the 5 patients received transfusion the day of admission. CONCLUSION: Hemodynamically stable patients with blunt spleen/liver injury triaged to conservative management should have their blood typed and be monitored closely for signs or laboratory values that would mandate a cross-match. According to our data, this strategy would safely improve utilization of blood bank resources.  相似文献   
93.

Introduction

Adhesive small bowel obstruction (SBO) is a common postoperative complication. Published data in the pediatric literature characterizing SBO are scant. Furthermore, the relationship between the risk of SBO for a given procedure is not well described. To evaluate these parameters, we reviewed the incidence of SBO after laparoscopic appendectomy (LA) and open appendectomy (OA) performed at our institution.

Methods

With institutional review board approval, all patients that developed SBO after appendectomy for appendicitis from January 1998 to June 2005 were investigated. Hospital records were reviewed to identify the details of their postappendectomy SBO. The incidences of SBO after LA and OA were compared with χ2 analysis using Yates correction.

Results

During the study period, 1105 appendectomies were performed: 477 OAs (8 converted to OA during laparoscopy) and 628 LAs. After OA, 7 (6 perforated appendicitis) patients later developed SBO of which 6 required adhesiolysis. In contrast, a patient with perforated appendicitis developed SBO after LA requiring adhesiolysis (P = .01). The mean time from appendectomy to the development of intestinal obstruction for the entire group was 46 ± 32 days.

Conclusions

The overall risk of SBO after appendectomy in children is low (0.7%) and is significantly related to perforated appendicitis. Small bowel obstruction after LA appears statistically less common than OA. Laparoscopic appendectomy remains our preferred approach for both perforated and nonperforated appendectomy.  相似文献   
94.
BACKGROUND: Isoniazid (INH) therapy for tuberculosis carries a known risk for hepatoxicity, and leads to hepatic failure in a small subset of patients. This incidence has been described for adults, but is uncertain in children. Our aim was to estimate the incidence of pediatric referrals for INH-related liver failure, and to describe the characteristics and outcomes of these patients. METHODS: The 84 U.S. centers performing pediatric liver transplants between 1987 and 1997 were surveyed regarding patients with INH-induced liver failure. Additional transplant statistics were obtained from the United Network for Organ Sharing. Estimates of the number of children taking preventive INH were derived from a nationwide public health database. RESULTS: Twenty cases of INH-related liver failure were found during a 10-year period. Four patients (20%) recovered spontaneously; 10 (50%) underwent orthotopic liver transplantation (OLT), while six (30%) died awaiting OLT. Mean age at presentation was 9.8 years (range 1.3-17). Mean length of INH therapy was 3.3 months (range 0.5-9). Notably, five patients seen for symptoms of hepatitis were initially told not to stop treatment. INH-associated liver failure accounted for 0.2% (8 of 4679) of all pediatric OLTs, and 14% (8/56) of transplants for drug hepatoxicity. The estimated incidence of liver failure was up to 3.2/100,000 for children on prophylactic INH. CONCLUSIONS: While INH-associated liver failure in children is rare, discontinuation at the onset of symptoms does not assure recovery. This indicates a need for increased awareness of hepatotoxicity risk, expanded biochemical monitoring for children receiving INH, and prompt withdrawal in symptomatic patients.  相似文献   
95.
INTRODUCTION: Laparoscopic fundoplication (LF) is rapidly replacing open fundoplication (OF) for correcting symptomatic gastroesophageal reflux (GER) in infants and children. In this study, we compared various clinical and financial parameters to determine if one technique is superior. METHODS: With Institutional Review Board approval, charts and charge data for 50 consecutive patients undergoing elective LF or OF were reviewed in 2003 and 2004 (n = 100). Clinical variables evaluated included gender, age, weight, length of stay (LOS), operating time (OT), and time to initial (IF) and full (FF) feedings. Financial charges that were reviewed included anesthesia, central supply and sterilization, equipment, operating suite, hospital room and board, pharmacy, and total charges. RESULTS: The groups were equally matched in relation to gender, age, and weight. The table below illustrates the statistically significant differences (P < 0.05) between the groups. Favoring LNF LOS (1.2 vs. 2.9 days) IF (7.3 vs. 27.9 hours) FF (21.8 vs. 42.9 hours) Equipment ($1,006 vs. $1,609) Hospital Room ($1,290 vs. $2,847) Pharmacy ($180 vs. $461), Favoring OF OT (77 vs. 91 minutes) Anesthesia ($389 vs. $475) Central Supply and Sterilization ($1,367 vs. $2,515) Operating Suite ($4,058 vs. $5,142) Total charges were similar (LF, $11,449; OF, $11,632). CONCLUSIONS: Interestingly, although there were statistical differences in every charge category, total charges for LF and OF did not differ significantly. Thus, traditionally higher expenses from longer OT for LF seem to be offset by financial benefits, such as shorter LOS, reduced discomfort as evidenced by lower narcotic charges, and earlier IF/FF.  相似文献   
96.
97.
98.
Internal herniations through broad ligament defects are very rare. We present the first report of the triad of broad ligament defect, internal herniation of the caecum and appendicitis. A 36-year-old woman with phocomelia presented with right iliac fossa pain and vomiting. The patient had no previous history of trauma or surgery. Abdominal ultrasound showed a small amount of free fluid. At laparoscopy, bilateral broad ligament defects were found, with herniation of the caecum and an inflamed appendix through the right-sided defect. A laparoscopic salpingo-oophorectomy was required for reduction of the herniated bowel, and an appendicectomy was performed. Broad ligament defects may be congenital or acquired. In this case, in light of the limb abnormality and absence of previous surgery, a congenital aetiology is more likely. Ultrasound scan is not reliable and, although computed tomography may be of help, a diagnostic laparoscopy is the best investigation.  相似文献   
99.
Prospective trials demonstrate that sentinel node (SN) biopsy after neo-adjuvant chemotherapy (NACT) has a significant false-negative rate (FNR) when only 1 or 2 SNs are removed. It is unknown whether this increased FNR correlates with an elevated risk of recurrence. Tumor Registry data at an NCI-Designated Comprehensive Cancer Center were reviewed from 2004 to 2018 for patients having a negative SN biopsy after NACT. Among 190 patients with histologically negative nodes after NACT having 1 (n = 42), 2 (n = 46), and ≥3 (n = 102) SNs, axillary recurrences occurred in 7.14%, 0%, and 1.96% (p = 0.09), breast recurrences occurred in 2.38%, 6.52%, and 0.98% (p = 0.12), and distance recurrences occurred in 16.67%, 8.70%, and 7.84% (p = 0.27), respectively. Time to first recurrence did not differ by SN count (p = 0.41). After adjustment for age, race, clinical stage, and receptor status, there were no differences in the rates of axillary (p = 0.26), breast (p = 0.44), or distance recurrence (p = 0.24) by numbers of SNs harvested. Median follow-up was 46.8 months. Despite higher post-NACT FNRs reported in randomized trials for patients having <3 sentinel nodes, recurrence rates were not significantly different for 1 versus 2 versus ≥3 SNs. This suggests that patients having 1 or 2 post-NACT SNs identified may not necessitate axillary dissection.  相似文献   
100.
Hyperinsulinism of infancy (HI) is a congenital defect in the regulated release of insulin from pancreatic beta-cells. Here we describe stimulus-secretion coupling mechanisms in beta-cells and intact islets of Langerhans isolated from three patients with a novel SUR1 gene defect. 2154+3 A to G SUR1 (GenBank accession number L78207) is the first report of familial HI among nonconsanguineous Caucasians identified in the U.K. Using patch-clamp methodologies, we have shown that this mutation is associated with both a decrease in the number of operational ATP-sensitive K+ channels (KATP channels) in beta-cells and impaired ADP-dependent regulation. There were no apparent defects in the regulation of Ca2+- and voltage-gated K+ channels or delayed rectifier K+ channels. Intact HI beta-cells were spontaneously electrically active and generating Ca2+ action currents that were largely insensitive to diazoxide and somatostatin. As a consequence, when intact HI islets were challenged with glucose and tolbutamide, there was no rise in intracellular free calcium ion concentration ([Ca2+]i) over basal values. Capacitance measurements used to monitor exocytosis in control and HI beta-cells revealed that there were no defects in Ca2+-dependent exocytotic events. Finally, insulin release studies documented that whereas tolbutamide failed to cause insulin secretion as a consequence of impaired [Ca2+]i signaling, glucose readily promoted insulin release. Glucose was also found to augment the actions of protein kinase C- and protein kinase A-dependent agonists in the absence of extracellular Ca2+. These findings document the relationship between SUR1 gene defects and insulin secretion in vivo and in vitro and describe for the first time KATP channel-independent pathways of regulated insulin secretion in diseased human beta-cells.  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