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   3658篇
  免费   184篇
  国内免费   18篇
耳鼻咽喉   15篇
儿科学   45篇
妇产科学   53篇
基础医学   434篇
口腔科学   135篇
临床医学   280篇
内科学   879篇
皮肤病学   63篇
神经病学   207篇
特种医学   134篇
外科学   724篇
综合类   22篇
预防医学   70篇
眼科学   52篇
药学   318篇
中国医学   14篇
肿瘤学   415篇
  2023年   20篇
  2022年   40篇
  2021年   66篇
  2020年   31篇
  2019年   55篇
  2018年   60篇
  2017年   55篇
  2016年   70篇
  2015年   60篇
  2014年   91篇
  2013年   97篇
  2012年   191篇
  2011年   201篇
  2010年   127篇
  2009年   81篇
  2008年   161篇
  2007年   210篇
  2006年   204篇
  2005年   220篇
  2004年   209篇
  2003年   190篇
  2002年   212篇
  2001年   124篇
  2000年   130篇
  1999年   118篇
  1998年   51篇
  1997年   47篇
  1996年   37篇
  1995年   36篇
  1994年   33篇
  1993年   22篇
  1992年   62篇
  1991年   57篇
  1990年   52篇
  1989年   54篇
  1988年   63篇
  1987年   30篇
  1986年   26篇
  1985年   29篇
  1984年   33篇
  1983年   27篇
  1982年   11篇
  1980年   11篇
  1979年   26篇
  1978年   20篇
  1977年   9篇
  1974年   14篇
  1972年   9篇
  1968年   14篇
  1967年   11篇
排序方式: 共有3860条查询结果,搜索用时 15 毫秒
41.
OBJECTIVE: To evaluate the diagnostic accuracy of fluorodeoxyglucose positron emission tomography (FDG-PET) relative to computed tomography (CT) for detecting metastatic cervical lymph nodes in patients with squamous cell carcinoma of the head and neck (HNSCC), and to ascertain the factors that affect this accuracy. METHODS: A total of 1076 lymph nodes obtained from 35 neck dissections in 26 HNSCC patients who preoperatively underwent both FDG-PET and CT were retrospectively analyzed. For pathological metastatic lymph nodes, the lymph node size (short-axis diameter), the ratio of intranodal tumor deposits, and the size of intranodal tumor deposits (maximum diameter of metastatic foci in each lymph node) were histologically recorded. RESULTS: Forty-six lymph nodes from 23 neck sides were pathologically diagnosed metastases. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG-PET evaluated individually per neck side were 74%, 92%, 80%, 94%, and 65%, respectively, whereas those of CT were 78%, 58%, 71%, 78%, and 58%, respectively. FDG-PET detected 100% of metastatic lymph nodes > or =10 mm, intranodal tumor deposits > or =9 mm, and intranodal tumor deposits with a ratio >75%, whereas no nodes or tumor deposits smaller than 5 mm were detected. The spatial resolution limitations of FDG-PET were responsible for 16 of 20 (80%) false-negative PET results in lymph nodes. CONCLUSIONS: FDG-PET is a useful tool for preoperative evaluation of the neck because it accurately detects metastatic lymph nodes > or =10 mm and has fewer false-positive cases than CT. The high specificity of FDG-PET for lymph node metastases may play an important role in avoiding unnecessary neck dissection.  相似文献   
42.
A 5-month-old boy was presented for surgical repair of scimitar syndrome associated with right lung hyperplasia, severe pulmonary hypertension, ventricular septal defect (VSD), and atrial septal defect. The calculated shunt fraction (Qp/Qs) was 3.1:1.0, pulmonary vascular resistance was 4.6, and the perfusion lung scan showed a marked decrease (11%) in right pulmonary blood flow. Surgical repair was performed through the right fourth intercostal space with the patient supine. The anomalous vein was divided and interposed with a short azygos vein graft, followed by closure of the VSD. Finally, the interposed azygos vein was anastomosed to the left atrium. Although pulmonary artery pressure was normalized at the 2-year follow-up, cardiac catheterization 6 months after the operation demonstrated right pulmonary vein obstruction.  相似文献   
43.
OBJECTIVE: There is no criterion for the timing of surgical resection of pulmonary metastasis. In this study, we investigated the optimal period for pulmonary metastasectomy. METHODS: Between 2000 and 2005, 68 patients underwent complete pulmonary resection of metastatic cancer. Clinical prognostic factor in multivariate analysis was examined. RESULTS: The interval from pulmonary metastasectomy until subsequent recurrence and the interval from detection of pulmonary metastasis until pulmonary metastasectomy were independent prognostic factors. To investigate the relationship between the two characteristics, the 68 patients were divided into two groups according to the interval from lung metastasectomy until subsequent recurrence. Nineteen patients relapsed within 1 year after pulmonary metastasectomy (group A), while 49 patients did not relapse within 1 year (group B). The interval from detection of pulmonary metastasis until pulmonary metastasectomy was significantly shorter in group A than in group B (2.9 months vs 7.1 months, p=0.01). Based on these results, we divided the patients into two different groups and survival was compared. Significantly shorter survival was observed in the patients who underwent pulmonary metastasectomy within 3 months after detection of pulmonary metastasis (group X, n=35) than in those who underwent the surgery beyond 3 months (group Y, n=33). CONCLUSIONS: There were many cases of early relapse after metastasectomy when the interval from detection of pulmonary metastasis until pulmonary metastasectomy was short. Performing metastasectomy at least three months after detection of pulmonary metastasis may significantly improve the prognosis of patients.  相似文献   
44.
BACKGROUND: Microwave coagulation therapy (MCT) has become a safe and effective modality with which to treat hepatic tumors; MCT can be applied percutaneously, laparoscopically, thoracoscopically, and during laparotomy. When combined with magnetic resonance (MR) imaging, MCT can be used to treat hepatic tumors located in the subdiaphragmatic area that are difficult to approach by ultrasound, because of the overlaying lower lung field. METHODS: To determine the usefulness of thoracoscopy-assisted interventional MR-MCT (T-IVMR-MCT, n = 73), we compared patients with hepatic tumors that were treated with percutaneous IVMR-MCT (P-IVMR-MCT, n = 69) and with T-IVMR-MCT. RESULTS: None of patient background, complication and recurrence rate, or length of hospital stay significantly differed between the 2 groups. CONCLUSIONS: IVMR-MCT is a useful modality for treating hepatic tumors. Especially when tumors are located at the hepatic dome, T-IVMR-MCT was minimally invasive, while it appears to improve targeting of peridiagmatic hepatic lesions and has a complication profile similar to P-IVMR-MCT.  相似文献   
45.
In our experience, the prognosis of patients with pathological T3N0M0 lung cancer is generally poor, the 5-year survival rate being almost the same as that of patients with stage IIIA disease. Thus, we assessed patients with stage IIB disease by examining the pathological factors, lymphatic invasion, vessel invasion, histological type, differentiation, tumor size, and node dissection. Lymphatic invasion was found to be positive in 20 of 21 cases, patients with T3N0M0 lung cancer, and all of those with positive vessel invasion had a significantly poor prognosis. This indicates that positive lymphatic and vessel invasion could be a prognostic factor predicting a poor outcome. Patients with T3N0M0 lung cancer that are found to have this poor prognostic factor may not be diagnosed as having stage IIB disease.  相似文献   
46.
AIM: Vein graft stenosis due to intimal hyperplasia (IH) is the main cause of graft failure. We examined possibilities of nuclear factor-kB (NF-kB) expression in vein grafts, and inhibitive effects of NF-kB decoy on the gene expression and subsequent vein graft IH. METHODS: Fifteen mongrel dogs underwent femoral artery replacement with autogenous vein grafts. Group I: grafts were retrieved at a predetermined time and subjected to NF-kB binding activity assay; Groups II and III: grafts were transfected with scrambled (II-a, III-a) or NF-kB (II-b, III-b) decoy using hemagglutinating virus of Japan envelope before implantation. Grafts were retrieved 7 days after implantation for evaluation of intercellular adhesion molecule-1 (ICAM-1) mRNA expression (Group II) and 4 weeks after implantation for comparison of IH by morphometric analysis (Group III). RESULTS: NF-kB binding activity was increased in a time-dependent manner, with a peak 2 days after implantation. The ratio between ICAM-1 and glyceraldehyde-3-phosphate dehydrogenase mRNA expression in II-b was significantly lower than that in II-a (0.347 +/- 0.07 versus 0.612+/-0.08; P = 0.047). The ratio of intimal cross-section area to luminal cross-section area of III-b was significantly lower than that of the III-a (0.096+/-0.03 versus 0.461+/-0.11; P = 0.048). CONCLUSION: NF-kB binding activity in vein grafts increases after implantation, and transfection of NF-kB decoy before implantation may reduce IH through the inhibition of ICAM-1 expression.  相似文献   
47.
We report a 71-year-old man who had undergone pylorus-preserving pancreatoduodenectomy (PPPD) using PPPD-IV reconstruction for cholangiocarcinoma. For 6 years thereafter, he had suffered recurrent cholangitis, and also a right liver abscess (S5/8), which required percutaneous drainage at 9 years after PPPD. At 16 years after PPPD, he had been admitted to the other hospital because of acute purulent cholangitis. Although medical treatment resolved the cholangitis, the patient was referred to our hospital because of dilatation of the intrahepatic biliary duct (B2). Peroral double-balloon enteroscopy revealed that the diameter of the hepaticojejunostomy anastomosis was 12 mm, and cholangiography detected intrahepatic stones. Lithotripsy was performed using a basket catheter. At 1 year after lithotripsy procedure, the patient is doing well. Hepatobiliary scintigraphy at 60 minutes after intravenous injection demonstrated that deposit of the tracer still remained in the upper afferent loop jejunum. Therefore, we considered that the recurrent cholangitis, liver abscess, and intrahepatic lithiasis have been caused by biliary stasis due to nonobstructive afferent loop syndrome. Biliary retention due to nonobstructive afferent loop syndrome may cause recurrent cholangitis or liver abscess after hepaticojejunostomy, and double-balloon enteroscopy and hepatobiliary scintigraphy are useful for the diagnosis of nonobstructive afferent loop syndrome.Key words: Nonobstructive afferent loop syndrome, Biliary stasis, Hepaticojejunostomy, Hepatobiliary scintigraphy, Double-balloon enteroscopyIt has been reported that cholangitis occurs in between 6.7% and 14.3% of postoperative pancreatoduodenectomy (PD).1 Most cases of cholangitis originate due to biliary stasis, which is broadly caused by either anastomotic or nonanastomotic stenosis. In many cases, anastomotic stenosis is accompanied by intrahepatic biliary duct dilatation and obstructive jaundice, making early diagnosis and treatment possible.23 On the other hand, nonanastomotic stenosis, including those of afferent loop syndrome, is performed as a conservative treatment for unexplained fever and cholangitis. However, in many cases, the cause remains unidentified, thereby causing this condition to repeat itself. Since cholangitis can at times be fatal, it is therefore important to identify the cause.It has been reported that afferent loop syndrome occurs in around 13% of postoperative PD patients.4 Afferent loop syndrome is generally caused by mechanical occlusion due to the recurrence or metastasis of cancer,46 adhesion,78 torsion,9 internal hernia,10 enterolithiasis,1112 etc., and thereafter, leads to a syndrome associated with acute abdominal symptom or acute cholangitis. On the other hand, nonobstructive afferent loop syndrome may also be caused by biliary stasis due to jejunal motility failure or the length of the blind end or jejunum, and thereafter, leads to acute cholangitis, liver abscess, and the formation of enterolithiasis and intrahepatic stones. Nonobstructive afferent loop syndrome occurs in around 37% of all of the afferent loop syndrome,1213 but few cases have actually been reported.We herein report a rare case in which the patient experienced recurrent cholangitis and liver abscess by biliary stasis due to nonobstructive afferent loop syndrome after pylorus-preserving pancreatoduodenectomy (PPPD) for cholangiocarcinoma.  相似文献   
48.

Background

Double-balloon endoscopy (DBE) has become a new standard in enteroscopy. However, it may be difficult to make a diagnosis or plan treatment strategy with endoscopic visualization alone. The addition of endoscopic ultrasonography (EUS) has the potential to improve the ability to establish the diagnosis and develop a treatment strategy. The present study was conducted to assess the feasibility and usefulness of EUS with DBE.

Methods

EUS with DBE was performed in 31 of 891 patients who underwent DBE from July 2004 to March 2011 at Jichi Medical University Hospital. We analyzed the EUS findings for lesions and evaluated the usefulness of EUS considering the following three factors: qualitative diagnostic value for lesions, depth grading of lesions, and evaluation of the structure of severe strictures prior to endoscopic balloon dilation.

Results

EUS was performed for 31/32 lesions (97 %) in 31 patients. EUS findings were informative for 29/32 lesions (91 %). EUS findings were useful for establishing a qualitative diagnosis in 15/25 lesions (60 %). EUS findings for depth grading provided useful information for determining the therapeutic strategy in 11/13 lesions (85 %). EUS with DBE was useful in the evaluation of strictures for all six lesions (100 %). The overall usefulness of EUS with DBE on decision making was 72 % (23/32) in this study.

Conclusions

EUS with DBE is feasible and useful. It provides additional information on small-bowel disease and contributes to establishing a precise diagnosis and selection of an appropriate therapeutic strategy.  相似文献   
49.
Objective Antegrade selective cerebral perfusion (ASCP) and retrograde cerebral perfusion (RCP) have proven to be reliable methods of brain protection during aortic surgery. These techniques are usually accompanied by systemic circulatory arrest with moderate hypothermia (24–28°C) or deep hypothermia (18–24°C). However, hypothermia can lead to various problems. The present study therefore reports results for thoracic aorta replacement using ASCP with mild hypothermic systemic arrest (28–32°C).

Design Between 1995 and 2003, 68 consecutive patients underwent repair of the ascending aorta and/or aortic arch. Mild hypothermic ASCP was utilized in 31 cases, moderate hypothermic ASCP in 20, and deep hypothermic RCP in 17. Various parameters were compared between the mild hypothermic ASCP, moderate hypothermic ASCP, and RCP.

Results Hospital mortality was 10.3%, with no significant differences observed between any groups. Permanent neurological dysfunction was 8.8%, and no significant differences were observed between any groups. Mild hypothermic ASCP displayed significantly decreased transfusion volume, intubation time, and ICU stay.

Conclusions Use of ASCP with mild hypothermic systemic circulatory arrest during aortic surgery resulted in acceptable hospital mortality and neurological outcomes. ASCP with mild hypothermic arrest allows decreased transfusion volume and reduced duration of intubation and ICU stay.  相似文献   
50.
The ability of autologous nerve segments interposed between allografts, to increase the total nerve-gap distance, was studied. Sciatic nerve allografts were carried out in a rat model. A 15-mm nerve gap was repaired with a 25-mm nerve graft (interposed group: allo-auto-allograft; control group: allo-allo-allograft). Cyclosporin was given for 12 weeks. Nerve regeneration was evaluated using the weight of the anterior tibial muscle and histologic, morphometric and immunohistochemical analyses at 12, 13, 14, 15, 16, 20, and 24 weeks. Nerve regeneration in the interposed group was statistically significantly better than that in the control group. The authors concluded that a nerve allograft with interposed autograft may enhance nerve regeneration in this model, because of the migration of host-derived Schwann cells into the graft from not only the proximal and distal host nerve stumps, but also the interposed autograft.  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