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   6462篇
  免费   246篇
  国内免费   47篇
耳鼻咽喉   33篇
儿科学   85篇
妇产科学   45篇
基础医学   856篇
口腔科学   483篇
临床医学   371篇
内科学   1597篇
皮肤病学   73篇
神经病学   291篇
特种医学   390篇
外科学   1020篇
综合类   59篇
一般理论   6篇
预防医学   187篇
眼科学   123篇
药学   283篇
中国医学   26篇
肿瘤学   827篇
  2023年   41篇
  2022年   64篇
  2021年   137篇
  2020年   91篇
  2019年   94篇
  2018年   122篇
  2017年   98篇
  2016年   126篇
  2015年   132篇
  2014年   174篇
  2013年   193篇
  2012年   359篇
  2011年   396篇
  2010年   245篇
  2009年   179篇
  2008年   346篇
  2007年   419篇
  2006年   374篇
  2005年   396篇
  2004年   398篇
  2003年   374篇
  2002年   352篇
  2001年   113篇
  2000年   129篇
  1999年   142篇
  1998年   87篇
  1997年   70篇
  1996年   74篇
  1995年   80篇
  1994年   50篇
  1993年   41篇
  1992年   61篇
  1991年   74篇
  1990年   65篇
  1989年   67篇
  1988年   69篇
  1987年   65篇
  1986年   49篇
  1985年   45篇
  1984年   41篇
  1983年   29篇
  1982年   24篇
  1980年   26篇
  1979年   17篇
  1977年   22篇
  1975年   16篇
  1973年   21篇
  1972年   19篇
  1971年   19篇
  1969年   18篇
排序方式: 共有6755条查询结果,搜索用时 15 毫秒
71.

Background

Colorectal liver metastases with hepatic vein (HV) involvement may require combined resection of the liver and HV. However, the short- and long-term outcomes of such a procedure remain unclear.

Methods

We reviewed 16 cases of liver resection with major HV resection and reconstruction.

Results

The patients had a median age of 58.5 years (range, 50–74 y). In total, 18 HVs were reconstructed using a customized great saphenous vein graft (n = 10), direct anastomosis (n = 1), external iliac vein (n = 2), portal vein (n = 1), umbilical vein patch graft (n = 3), or ovarian vein patch graft (n = 1). There was no hospital mortality, and the morbidity rate was 50%. With a median follow-up period of 30 months (range, 4–89 mo), 3 patients died of tumor recurrence and 13 were alive with (n = 6) and without (n = 7) disease. Cumulative 1-, 3-, and 5-year survival rates were 93%, 76%, and 76%, respectively.

Conclusions

HV resection and reconstruction combined with liver resection can be performed safely with reasonable long-term results.  相似文献   
72.
OBJECTIVE: We sought to improve the efficiency of dentin ablation with the Er:YAG laser by investigating the effects of output energy and pulse repetition rate on ablation. Background Data: The Er:YAG laser is superior to other lasers in ablating dental hard tissues. However, the factors affecting the efficiency of ablation with an Er:YAG laser remain unclear. METHODS: Fifty bovine root dentin plates were irradiated with an Er:YAG laser at an output power of 1.0 W, 1.5 W, or 2.0 W under a water spray while moving the plate at 1 mm/sec. After irradiation, the depth and volume of each ablated site were measured by laser microscopy and the ablated surfaces were examined by scanning electron microscopy. RESULTS: The output power showed a strong positive correlation with the depth and volume of ablation. The output energy had much more pronounced effects on the depth and volume of ablation compared to the pulse repetition rate. The shape of the ablated site varied with the output power, and no cracking or vitrification was observed under the irradiated dentin. The most effective parameters for dentin ablation were an output power of 2.0 W, with an output energy of 80 mJ/pulse at 25 pulses per second (pps) or 100 mJ/pulse at 20 pps. CONCLUSION: These findings suggest that the output energy is the main factor affecting the efficiency of dentin ablation with an Er:YAG laser. We propose that the efficiency of dentin ablation can be improved by choosing an optimal combination of output energy and repetition rate.  相似文献   
73.
No strategies for the diagnosis and treatment of biliary tract carcinoma have been clearly described. We developed flowcharts for the diagnosis and treatment of biliary tract carcinoma on the basis of the best clinical evidence. Risk factors for bile duct carcinoma are a dilated type of pancreaticobiliary maljunction (PBM) and primary sclerosing cholangitis. A nondilated type of PBM is a risk factor for gallbladder carcinoma. Symptoms that may indicate biliary tract carcinoma are jaundice and pain in the upper right area of the abdomen. The first step of diagnosis is to carry out blood biochemistry tests and ultrasonography (US) of the abdomen. The second step of diagnosis is to find the local extension of the carcinoma by means of computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP), percutaneous transhepatic cholangiography (PTC), and endoscopic retrograde cholangiopancreatography (ERCP). Because resection is the only way to completely cure biliary tract carcinoma, the indications for resection are determined first. In patients with resectable disease, the indications for biliary drainage or portal vein embolization (PVE) are checked. In those with nonresectable disease, biliary stenting, chemotherapy, radiotherapy, and/or best supportive care is selected.  相似文献   
74.
Only 10% to 20% of patients with primary and colorectal metastatic liver tumors are candidates for curative surgical resection. Even after curative treatment, tumors recur commonly in the liver. As a less invasive therapy, radiofrequency thermal ablation (RFA) of primary, metastatic, and recurrent liver tumors was performed under percutaneous, laparoscopic, or open intraoperative ultrasound guidance. The safety and local control efficacy of RFA were investigated. RFA was performed mostly in patients with unresectable hepatomas or metastatic liver tumors. Patients with large tumors, major vessel or bile duct invasion, limited extrahepatic metastases, or liver dysfunction were not excluded. An RFA system with a 15-gauge electrode-cannula with four-pronged retractable needles was used. All patients were followed for more than 8 months to assess morbidity and mortality, and to determine tumor recurrence. Sixty RFA operations were performed in 46 patients: 11 patients underwent repeat RFA once or twice. A total of 204 tumors were treated: 70 hepatomas and 134 metastatic tumors. Tumor size ranged from 5 mm to 180 mm (mean 36 mm). RFA was performed in 29 operations for 81 tumors percutaneously, in seven operations for 14 tumors laparoscopically, and in 24 operations for 109 tumors by open surgery. Combined colorectal resection was carried out in five operations and combined hepatic resection was carried out in three operations. There was one death (1.7%) from liver failure, and there were three major complications (5%): one case of bile leakage and two biliary strictures due to thermal injury. There were no intra-abdominal infectious or bleeding complications. The length of hospital stay ranged from 0 to 2, 1 to 3, and 4 to 7 days for percutaneous, laparoscopic, and open surgical RFA, respectively. During a mean follow-up period of 20.5 months, local tumor recurrence at the RFA site was diagnosed in 18 (8.8%) of 204 tumors. The risk factors for local recurrence included large tumor size and major vessel invasion: recurrence rates for tumors less than 4 cm, 4 to 10 cm, and greater than 10 cm, and for those with vessel invasion were 3.3%, 14.7%) 50%) and 47.8%) respectively. Ten of 18 tumors recurring locally were retreated by RFA, and eight of them showed no further recurrence. Ultrasound-guided RFA is a relatively safe, well-tolerated, and versatile treatment option that offers excellent local control of primary and metastatic liver tumors. The appropriate use of percutaneous, laparoscopic, and open surgical RFA is beneficial in the management of patients with liver tumors in a variety of situations.  相似文献   
75.
Background: It is recognized that matrix metalloproteinase‐3 (MMP‐3) is abundantly expressed in active rheumatoid synovium, and that serum level of MMP‐3 is a useful marker for diagnosis of rheumatoid arthritis and for evaluation of prognosis in joint destruction. Little is known about serum MMP‐3 levels in haemodialysis (HD) patients, and thus, the association between serum MMP‐3 and dialysis‐related amyloidosis (DRA) has yet to be elucidated. Methods: Serum levels of MMP‐3 were measured by enzyme immunoassay in 150 HD patients, 90 without DRA and 60 with DRA, before HD. Simple regression analysis was performed to investigate the relationship between serum level of MMP‐3 and clinical parameters, including age, HD duration, C‐reactive protein and β2 microglobulin (BMG). Results: Serum levels of MMP‐3 were significantly higher in HD patients with DRA than in HD patients without DRA (258.2 ± 118.1 vs 201.5 ± 98.4 pg/mL, P = 0.0017), and both levels were significantly higher than those of healthy subjects (45.6 ± 13.4 pg/mL, P < 0.0001). Serum MMP‐3 levels significantly correlated with serum levels of BMG (r = 0.197, P = 0.0164) and HD duration (r = 0.168, P = 0.0427). Moreover, serum MMP‐3 levels significantly correlated with serum BMG levels in HD patients without DRA (r = 0.341, P = 0.0012), but not in HD patients with DRA. Conclusion: Our results suggest that matrix metalloproteinase activity increases in HD patients, which may be associated with BMG and DRA.  相似文献   
76.
OBJECTIVES: To evaluate whether three-dimensional 26-core (3D26) prostate biopsy improves the accuracy in predicting the presence of Gleason pattern 4/5 cancer compared with extended transrectal 12-core (TR12) or transperineal 14-core (TP14) biopsy schemes. METHODS: We studied 143 consecutive men in whom prostate cancer was diagnosed by the 3D26 biopsy and who underwent radical prostatectomy (RP) without neoadjuvant treatment. All histologic grading was reevaluated by a single pathologist according to the 2005 International Society of Urological Pathology Consensus Conference on Gleason Grading. Cancer grade was categorized into high grade (Gleason pattern 4/5 cancer present) and non-high grade (absent) in both biopsy and RP specimens. Since TR12 and TP14 biopsy schemes represent subsets of the 3D26 biopsy, we could compare these schemes directly in an identical patient cohort. RESULTS: There was a grade agreement between 3D26 biopsy and RP in 132 (92.3%) cancers. Grade concordance between biopsy and RP was significantly better in 3D26 biopsy than in TR12 (83.5%, p=0.025) biopsy. Risk of underestimation of cancer grade by 3D26 biopsy (26.5%) was significantly lower than that by TP14 (51.4%, p=0.034). Grade concordance between 3D26 biopsy and RP was not according to clinical variables including prostate volume, clinical stage, prostate-specific antigen (PSA), and PSA density. CONCLUSIONS: We demonstrated that the 3D26 biopsy can accurately predict the presence of Gleason pattern 4/5 cancer on RP specimens with a high concordance rate of 92.3%, a value significantly higher than that between extended TR12 biopsy and RP specimens.  相似文献   
77.
BACKGROUND: The use of cell transplantation as an alternative therapy for orthotopic liver transplantation has been widely anticipated due to a chronic donor shortage. We previously reported the method used to enrich hepatic progenitor cells (HPCs) forming cell aggregations. In this study, we transplanted HPCs into the liver injury model mice to determine whether HPC transplantation may improve the liver dysfunction. METHODS: We obtained donor cells from E13.5 fetal livers of green fluorescent protein (GFP) transgenic mice. We transplanted GFP-positive fetal liver cells into the transgenic mice which express diphtheria toxin (DT) receptors under the control of an albumin enhancer/promoter. Subsequently, we induced selective liver injury to recipient mice by DT administration. We then evaluated the engraftment of the transplanted cells and their effect on survivorship. RESULTS: The low dose of DT induced sublethal liver injury and the high dose of DT was lethal to the liver injury model mice. The transplanted GFP-positive cells were engrafted into the recipient livers and expressed albumin, resembling mature hepatocytes. They continued to proliferate, forming clusters. The survival rate at 25 days after transplantation of the cell-transplanted group (8 of 20; 40.0%) was improved significantly (P=0.0047) in comparison to that of the sham-operated group (0 of 20; 0%). CONCLUSIONS: The transplanted cells were engrafted and repopulated the liver of recipient mice, resulting in the improvement of the survival rate of the liver injury model mice. We therefore propose that HPCs are a desirable cell source for cell transplantation.  相似文献   
78.
A case of bilateral pheochromocytomas with von Hippel Lindau disease (VHL) is reported. A 32-year-old man visited Kumamoto Red Cross Hospital for further examination of hypertension. Computed tomography revealed bilateral adrenal tumors and noradrenalin levels in serum and urine were elevated. Suspecting bilateral pheochromocytoma, he was reffered to our hospital for further examination and treatment. 131I-MIBG scintigraphy showed accumulation in bilateral adrenal glands. Moreover, he had cerebellar and spinal hemangioblastomas. Bilateral adrenalectomies and left nephrectomy were performed because tumor thrombus extended into the left renal vein, and pathological diagnosis was pheochromocytoma. His sister had been diagnosed as VHL disease. We diagnosed the patient as VHL disease because of the existence of cerebellar and spinal hemangioblastomas, bilateral pheochromocytomas, missense mutation and his family history. This is the eleventh case of bilateral pheochromocytomas with VHL disease reported in Japanese literatures.  相似文献   
79.
80.
Maintaining hepatic inflow and appropriate venous drainage is important for maximizing the capacity of the retrieved graft in liver transplantation. Here, we report a successful case of multiple hepatic vein (HV) reconstruction using an all-in-one sleeve patch graft of the autologous great saphenous vein to ensure adequate blood flow through the HV. A patient with hepatocellular carcinoma caused by hepatitis C virus–induced cirrhosis underwent living donor liver transplantation using a right lobe graft. A preoperative dynamic computed tomography scan and intraoperative findings revealed that the graft had three middle HV tributaries, a superficial vein, segment VIII HV (V8), and segment V HV (V5). The openings of the superficial vein and V8 were located very close to that of the right hepatic vein (RHV) in the cutting surface. Each HV had significant diameter and drainage territory requiring reconstruction. An autologous great saphenous vein was used to create a sleeve patch to incorporate the close-packed HV openings. The autologous sleeve patch graft was sutured to the openings of the RHV and the superficial vein and the hole created on the sleeve patch graft was anastomosed to the openings of V8 directly on the back table to create an all-in-one sleeve patch. For the V5 reconstruction, the recipient's intrahepatic portal vein graft was used to create an interpositional conduit from the recipient's V5 to the inferior vena cava. The postoperative course was uneventful and postoperative studies revealed good graft function with excellent blood flow in the HV.  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