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   24134篇
  免费   1118篇
  国内免费   130篇
耳鼻咽喉   167篇
儿科学   378篇
妇产科学   405篇
基础医学   2957篇
口腔科学   559篇
临床医学   1603篇
内科学   6323篇
皮肤病学   355篇
神经病学   1927篇
特种医学   1015篇
外科学   4049篇
综合类   108篇
一般理论   1篇
预防医学   614篇
眼科学   587篇
药学   1741篇
中国医学   82篇
肿瘤学   2511篇
  2023年   117篇
  2022年   236篇
  2021年   379篇
  2020年   279篇
  2019年   317篇
  2018年   416篇
  2017年   330篇
  2016年   411篇
  2015年   435篇
  2014年   579篇
  2013年   720篇
  2012年   1200篇
  2011年   1217篇
  2010年   712篇
  2009年   541篇
  2008年   1054篇
  2007年   1159篇
  2006年   1044篇
  2005年   1124篇
  2004年   1227篇
  2003年   1158篇
  2002年   1127篇
  2001年   853篇
  2000年   875篇
  1999年   805篇
  1998年   335篇
  1997年   271篇
  1996年   221篇
  1995年   199篇
  1994年   200篇
  1993年   167篇
  1992年   566篇
  1991年   485篇
  1990年   490篇
  1989年   493篇
  1988年   434篇
  1987年   375篇
  1986年   360篇
  1985年   361篇
  1984年   250篇
  1983年   186篇
  1982年   92篇
  1979年   171篇
  1978年   125篇
  1977年   121篇
  1974年   90篇
  1972年   93篇
  1971年   96篇
  1968年   96篇
  1967年   90篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
OBJECTIVE: To better determine the role of portal vein resection and its effect on survival, as well as to appreciate the impact of portal vein invasion on prognosis in hilar cholangiocarcinoma. SUMMARY BACKGROUND DATA: Hepatectomy with portal vein resection is sometimes performed for locally advanced hilar cholangiocarcinoma. However, the significance of microscopic invasion of the portal vein has not been determined. METHODS: Medical records of 160 patients with hilar cholangiocarcinoma who underwent macroscopically curative hepatectomy with (n = 52) or without portal vein resection (n = 108) were reviewed. Invasion of the portal vein was assessed histologically on the surgical specimen, and results were correlated with clinicopathologic features and survival. RESULTS: Surgical mortality, including all hospital deaths, was similar in patients who did and did not undergo portal vein resection (9.6% vs. 9.3%), but the primary tumor was more advanced in patients who underwent portal vein resection. Histologically, no invasion was found in 16 (30.8%) of resected portal veins. However, dense fibrosis adjacent to the portal vein was common, and the mean distance between the leading edge of cancer cells and the adventitia of the portal vein was 437 +/- 431 mum. The prognosis was worse in patients with than without portal vein resection (5-year survival, 9.9% vs. 36.8%; P < 0.0001). The presence or absence of microscopic invasion of the resected portal vein did not influence survival (16.6 months in patients with microscopic invasion vs. 19.4 months in those without; P = 0.1506). Multivariate analysis identified histologic differentiation, lymph node metastasis, and macroscopic portal vein invasion as independent prognostic factors. CONCLUSIONS: Microscopic invasion of the portal vein may be misdiagnosed clinically in patients with hilar cholangiocarcinoma. However, the distance between tumor and adventitia is so narrow that curative resection without portal vein resection is unlikely to be possible. Gross portal vein invasion has a negative impact on survival, and hepatectomy with portal vein resection can offer long-term survival in some patients with advanced hilar cholangiocarcinoma.  相似文献   
992.
Twenty-six patients who underwent pyloruspreserving pancreaticoduodenectomy (PPPD) for ductal cancer of the head of the pancreas between 1983 and 1993 were reviewed. Gastrointestinal continuity was restored by the methods of Imanaga (n=21) and Traverso (n=5). Combined resection of the portal vein and/or superior mesenteric vein was performed in 13 patients. Surgical complications occurred in 5 patients, but there were no postoperative deaths. Delayed gastric emptying was observed in 42% of patients. The median survival time for all 26 patients was 13 months. Three patients survived for more than 3 years, and one of them is currently alive without recurrence at 10 years. Differences in survival rates were not apparent between patients who underwent PPPD with and without portal vein resection. Survival rate after PPPD was compared with that after pancreaticoduodenectomy (PD) performed between 1974 and 1992; the difference was not significant. Patients who underwent noncurative PPPD had a significantly better survival rate than those who underwent noncurative PD (P<0.05). PPPD has improved the quality of life of the resected patients, without reducing survival rate. At present, PPPD by the Imanaga procedure could be the best choice for management of cancer of the pancreatic head.  相似文献   
993.
We hypothesized that environmental factors might affect the relationship between genetic predisposition and the risk of bone mineral density (BMD) loss. Cases were 114 Japanese women with a confirmed diagnosis of postmenopausal osteoporosis and controls were 171 general Japanese women. Genetic risk of SNPs in the estrogen receptors was analyzed by a case–control study. The interaction between gene and environmental factors for osteoporosis were assessed by a case‐only design. Significant increases in osteoporosis risk were observed with minor alleles of rs2077647 located in the first exon and rs2234693 located in the first intron of estrogen receptor α (ESRα). Haplotype CC at these risk SNPs was strongly associated with osteoporosis risk (odds ratio [OR] = 3.15, 95% confidence interval [CI] = 1.83–5.41). There was a statistically significant interaction between haplotype CC and alcohol drinking; moderate alcohol consumption decreased genetic risk of osteoporosis (OR = 0.22, 95%CI = 0.05–0.83). © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1529–1534, 2012  相似文献   
994.
The purpose of this study was to understand the mechanism responsible for joint capsule shrinkage after nonablative laser application in an in-vitro sheep model. Femoropatellar joint capsular tissue specimens harvested from 20 adult sheep were treated with one of three power settings of a holmium:yttrium-aluminum-garnet laser or served as a control. Laser treatment significantly shortened the tissue and decreased tissue stiffness in all three laser groups, whereas failure strength was not altered significantly by laser treatment. Transmission electron microscopic examination showed swollen collagen fibrils and loss of membrane integrity of fibroblasts. A thermometric study revealed nonablative laser energy caused tissue temperature to rise in the range of 64 degrees C to 100 degrees C. Electrophoresis after trypsin digestion of the tissue revealed significant loss of distinct alpha bands of Type I collagen in laser treated samples, whereas alpha bands were present in laser treated tissue without trypsin digestion. The results of this study support the concept that the primary mechanism responsible for the effect of nonablative laser energy is thermal denaturation of collagen in joint capsular tissue associated with unwinding of the triple helical structure of the collagen molecule.  相似文献   
995.

Objective

The purpose of this study was to clarify the priority of nodal dissection in Siewert types II and III adenocarcinoma of the esophagogastric junction (AEG).

Methods

The priority of nodal dissection was evaluated based on the therapeutic value index calculated by multiplying of the frequency of metastasis to each station and the 5-year survival rate of patients with metastasis to that station.

Results

A total of 176 patients (95 type II and 81 type III) were examined. Among the lymph nodes that had a metastatic incidence exceeding 10 %, the stations showing the first to fourth highest index were the paracardial and lesser curvature nodes (Nos. 1, 2, and 3) and the node at the root of the left gastric artery (No. 7) in the total cohort, as well as in each type. The next station was the lower thoracic paraesophageal lymph node (No. 110), followed by the nodes along the proximal splenic artery (No. 11p) in type II, whereas it was the nodes along the proximal splenic artery (No. 11p) followed by the para-aortic nodes (No. 16a2), the nodes at the celiac artery (No. 9), and the nodes around the splenic hilum (No. 10) in type III.

Conclusions

These results suggest that the highest priority nodal stations to be dissected were the paracardial and lesser curvature nodes (Nos. 1, 2, and 3) and the nodes at the root of the left gastric artery (No. 7), regardless of the Siewert subtype, but the subsequent priority was different depending on the subtype.  相似文献   
996.
We report the anesthetic management of two cases with placenta percreta that caused massive hemorrhage during cesarean section. These pregnant women, with a past history of cesarean section underwent elective operation after being diagnosed with total placenta previa and suspected adhesion of the placenta. The placenta percreta became evident after laparotomy and the patients underwent total hysterectomy after infant expulsion. They went into serious hemorrhagic shock, and recovered after the application of intensive cardiovascular support and blood transfusion. In recent years, the incidence of adhesion of the placenta has increased, but definitive, preoperative diagnosis is difficult; especially for the severe type: placenta percreta. Therefore, intensive management is necessary for the anesthesia of pregnant women with suspected adhesion of the placenta, including adequate preparation of transfused blood, since it might be difficult to save the mother's life after the onset of massive hemorrhage.  相似文献   
997.

Background

The Kidney Disease: Improving Global Outcomes (KDIGO) group proposed to adopt the 48-h time window for the 0.3  mg/dL rise in serum creatinine (sCr) proposed by the Acute Kidney Injury Network (AKIN) group as a modification to the original risk, injury, failure, loss, and end-stage renal disease criteria, keeping the 7-day window for the 50 % increase in sCr from baseline. The present study evaluates the prevalence of acute kidney injury (AKI) and the accuracy of predicting mortality based on the KDIGO and AKIN criteria.

Patients and methods

We retrospectively studied a cohort of 2579 patients admitted to the intensive care unit of Nagoya University Hospital between 2005 and 2009.

Results

The total AKI prevalence was higher according to the KDIGO than to the AKIN criteria (38.4 versus 29.5 %). In-hospital mortality rates were higher among 238 patients classified as non-AKI by the AKIN but AKI by the KDIGO criteria than among those classified as non-AKI by both criteria (7.1 versus 2.7 %). Survival curves generated using KDIGO significantly differed among all stages, but not between AKIN stages I and II. Multivariate analysis showed that KDIGO criteria were better in a statistical model than the AKIN criteria according to the Akaike information criterion. Harrell’s C statistic was greater for the KDIGO than for the AKIN criteria.

Conclusions

The KDIGO criteria have improved sensitivity without compromising specificity for AKI and might predict mortality at least as well as the AKIN criteria.  相似文献   
998.
Recently, endovascular management has been reported as a feasible option for Takayasu aortitis. However, few papers have focused on restenosis in the follow-up, and therefore, it is important to predict high-risk cases for restenosis after endovascular treatment. We herein report three cases with Takayasu aortitis showing repeated restenosis after endovascular percutaneous transluminal angioplasty (PTA)/stenting and discuss its clinical implications with a review of the literature. We should keep in mind that endovascular PTA/stenting for Takayasu aortitis does not always keep the patency of the affected vessels, and severity of the stenosis and/or uncontrollable systemic inflammation could be a risk factor for restenosis. Therefore, careful follow-up under strict control of inflammation is mandatory. Overall, this method is effective as an initial treatment since repeated PTA is available until collateral supply develops.  相似文献   
999.
STUDY DESIGN: Follow-up study of bioactive glass-ceramic graft for postero-lateral fusion (PLF) in the lumbar spine was performed using plain radiography. OBJECTIVES: To investigate the fusion state of the porous stick type of bioactive glass-ceramic which has been used in PLF in the lumbar spine, by plain radiography, and to evaluate the usefulness of this technique. METHODS: Fourteen patients who underwent PLF using apatite and wollastonite-containing glass-ceramic (A-W. GC) were followed-up for more than 1 year and 6 months by plain radiography. RESULTS: Six patients who were followed up for more than 2 years were considered to have obtained subtotal or total fusion. CONCLUSION: PLF using A-W. GC mixed with autologous grafted bone can preserve bone stock without the need to harvest a bone graft from the iliac crest and will be useful for PLF in the lumbar spine.  相似文献   
1000.
BACKGROUND: The techniques of right hepatic trisectionectomy are now standardized in patients with hepatocellular or metastatic carcinoma, but not in those with hilar cholangiocarcinoma. METHODS: Under preoperative diagnosis of hilar cholangiocarcinoma, 8 patients underwent "anatomic" right hepatic trisectionectomy with en bloc resection of the caudate lobe and the extrahepatic bile duct, in which the bile ducts of the left lateral section were divided at the left side of the umbilical fissure following complete dissection of the umbilical plate. RESULTS: Liver resection was successfully performed, and all patients were discharged from the hospital in good condition, giving a mortality of 0%. All patients were histologically diagnosed as having cholangiocarcinoma. The proximal resection margins were cancer-negative in 7 patients and cancer-positive in 1 patient. Four patients with multiple lymph node metastases died of cancer recurrence within 3 years after hepatectomy. One patient died of liver failure without recurrence 42 months after hepatectomy. The remaining 3 patients without lymph node metastasis are now alive after more than 5 years. CONCLUSIONS: Anatomic right hepatic trisectionectomy with caudate lobectomy can produce a longer proximal resection margin and can offer a better chance of long-term survival in some selected patients with advanced hilar cholangiocarcinoma.  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