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   8132篇
  免费   517篇
  国内免费   122篇
耳鼻咽喉   187篇
儿科学   113篇
妇产科学   59篇
基础医学   1286篇
口腔科学   109篇
临床医学   674篇
内科学   1595篇
皮肤病学   378篇
神经病学   575篇
特种医学   813篇
外科学   1161篇
综合类   26篇
一般理论   1篇
预防医学   189篇
眼科学   279篇
药学   625篇
中国医学   80篇
肿瘤学   621篇
  2023年   54篇
  2022年   163篇
  2021年   276篇
  2020年   166篇
  2019年   237篇
  2018年   254篇
  2017年   223篇
  2016年   359篇
  2015年   482篇
  2014年   531篇
  2013年   560篇
  2012年   842篇
  2011年   804篇
  2010年   498篇
  2009年   391篇
  2008年   471篇
  2007年   514篇
  2006年   449篇
  2005年   378篇
  2004年   324篇
  2003年   269篇
  2002年   212篇
  2001年   33篇
  2000年   31篇
  1999年   33篇
  1998年   41篇
  1997年   29篇
  1996年   19篇
  1995年   10篇
  1994年   15篇
  1993年   11篇
  1992年   12篇
  1991年   7篇
  1990年   9篇
  1989年   7篇
  1988年   8篇
  1987年   4篇
  1986年   5篇
  1985年   3篇
  1984年   6篇
  1983年   6篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1977年   2篇
  1976年   2篇
  1968年   2篇
  1965年   4篇
  1964年   1篇
  1961年   1篇
排序方式: 共有8771条查询结果,搜索用时 15 毫秒
991.
To evaluate the effectiveness of percutaneous removal of common bile duct (CBD) stones using a modified balloon technique (balloon catheter sphincteroplasty and expulsion of the stones using half-captured balloons within the sheath) in patients difficult to treat with endoscopy.Fifty patients underwent a modified balloon technique (balloon group), and 53 patients underwent CBD stone removal by the basket method (stone basket group) between 2016 and 2019. We compared the balloon and stone basket groups to evaluate the effectiveness of the modified balloon technique. Outcome variables such as demographics, technical success rates, procedural details, and complications were analyzed. Statistical analysis was performed using Student t test, Fisher exact test, or the χ2 test.The technical success rate in the balloon group was 66% (33/50) in 1 session, 32% (16/50) in 2 sessions, and 2% (1/50) in 3 sessions. That of the stone basket group was 45% (24/53) in 1 session, 38% (20/53) in 2 sessions, and 17% (9/53) in 3 sessions.The total procedure time was significantly shorter in the balloon group (29.5 ± 15.1 minutes) than in the stone basket group (41.7 ± 20.2 minutes) (P < .01), whereas the number of stones was higher in the balloon group than in the stone basket group (P = .03). Maximal stone size, balloon size, pancreatitis, and hospitalization stay did not show statistical differences between the 2 groups. Most complications (9 patients, balloon group; 8 patients, stone basket group) were mild and transient. Major complications occurred in one patient in the stone basket group, who experienced hemobilia due to arterial injury caused by percutaneous transhepatic biliary drainage, which was treated by endovascular embolization without mortality.The modified balloon technique is an effective and safe treatment method for CBD stone removal in patients presenting difficulties in the endoscopic approach.  相似文献   
992.
AIM:To determine the risk factors of biliary intervention using magnetic resonance cholangiopancreatography(MRCP) after living donor liver transplantation(LDLT).METHODS: We retrospectively enrolled 196 patients who underwent right lobe LDLT between 2006 and 2010 at a single liver transplantation center. Direct duct-to-duct biliary anastomosis was performed in all 196 patients. MRCP images routinely taken 1 mo after LDLT were analyzed to identify risk factors for biliary intervention during follow-up, such as retrograde cholangiopancreatography or percutaneous transhepatic biliary drainage. Two experienced radiologists evaluated the MRCP findings, including the anastomosis site angle on three-dimensional images, the length of the filling defect on maximum intensity projection, bile duct dilatation, biliary stricture, and leakage.RESULTS: Eighty-nine patients underwent biliary intervention during follow-up. The anastomosis site angle [hazard ratio(HR) = 0.48; 95% confidence interval(CI), 0.30-0.75, P 0.001], a filling defect in the anastomosis site(HR = 2.18, 95%CI: 1.41-3.38,P = 0.001), and biliary leakage(HR = 2.52, 95%CI: 1.02-6.20, P = 0.048) on MRCP were identified in the multivariate analysis as significant risk factors for biliary intervention during follow-up. Moreover, a narrower anastomosis site angle(i.e., below the median angle of 113.3°) was associated with earlier biliary intervention(38.5 ± 4.2 mo vs 62. 1 ± 4.1 mo, P 0.001). Kaplan-Meier analysis comparing biliary intervention-free survival according to the anastomosis site angle revealed that lower survival was associated with a narrower anastomosis site angle(36.3% vs 62.0%, P 0.001).CONCLUSION: The biliary anastomosis site angle in MRCP after LDLT may be associated with the need for biliary intervention.  相似文献   
993.
We evaluated the association between weight change in middle-aged adults and papillary thyroid cancer (PTC) based on a large-scale case-control study.Our study included data from 1551 PTC patients (19.3% men and 80.7% women) who underwent thyroidectomy at the 3 general hospitals in Korea and 15,510 individually matched control subjects. The subjects’ weight history, epidemiologic information, and tumor characteristics confirmed after thyroidectomy were analyzed. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were determined for the annual average changes in weight and obesity indicators (body mass index (BMI), body surface area, and body fat percentage (BF%) in subjects since the age of 35 years.Subjects with a total weight gain ≥10 kg after age 35 years were more likely to have PTC (men, OR, 5.39, 95% CI, 3.88–7.49; women, OR, 3.36, 95% CI, 2.87–3.93) compared with subjects with a stable weight (loss or gain <5 kg). A marked increase in BMI since age 35 years (annual average change of BMI ≥0.3 kg/m2/yr) was related to an elevated PTC risk, and the association was more pronounced for large-sized PTC risks (<1 cm, OR, 2.34, 95% CI, 1.92–2.85; ≥1 cm, OR, 4.00, 95% CI, 2.91–5.49, P heterogeneity = 0.005) compared with low PTC risks.Weight gain and annual increases in obesity indicators in middle-aged adults may increase the risk of developing PTC.  相似文献   
994.
995.
996.
The plant melatonin biosynthetic pathway has been well characterized, but inhibitors of melatonin synthesis have not been well studied. Here, we found that flavonoids potently inhibited plant melatonin synthesis. For example, flavonoids including morin and myricetin significantly inhibited purified, recombinant sheep serotonin N‐acetyltransferase (SNAT). Flavonoids also dose‐dependently and potently inhibited purified rice SNAT1 and SNAT2. Thus, myricetin (100 μmol/L) reduced rice SNAT1 and SNAT2 activity 7‐ and 10‐fold, respectively, and also strongly inhibited the N‐acetylserotonin methyltransferase activity of purified, recombinant rice caffeic acid O‐methyltransferase. To explore the in vivo effects, rice leaves were treated with flavonoids and then cadmium. Flavonoid‐treated leaves had lower melatonin levels than the untreated control. To explore the direct roles of flavonoids in melatonin biosynthesis, we first functionally characterized a putative rice flavonol synthase (FLS) in vitro and generated flavonoid‐rich transgenic rice plants that overexpressed FLS. Such plants produced more flavonoids but less melatonin than the wild‐type, which suggests that flavonoids indeed inhibit plant melatonin biosynthesis.  相似文献   
997.
Although adenocarcinoma is a well known complication of chronic inflammatory bowel disease, primary gastrointestinal lymphoma occurring in Crohn's disease is rare. A 40-year-old man with 10 year-history of Crohn's disease had multiple longitudinal ulcerative lesions on descending colon in follow-up colonoscopic examination. Microscopic examination of proximal descending colon revealed peripheral T cell lymphoma and other site of the descending colon was consistent with Crohn's disease. The patient reached complete remission of malignant lymphoma after three cycles of combined chemotherapy. He has been well for 10 months with sulfasalazine maintenance therapy but was admitted to the hospital due to spontaneous bowel perforation of ascending colon. Right hemicolectomy was done, but the patient died of post-surgical recurrent mesenteric abscess and sepsis. To the best of our knowledge, this is the first case of Non-Hodgkin's lymphoma complicating Crohn's disease in Korea which was confirmed by immunohistochemical studies.  相似文献   
998.
The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. Primary destabilizing N-terminal residues (Nd(p)) are recognized directly by the targeting machinery. The recognition of secondary destabilizing N-terminal residues (Nd(s)) is preceded by conjugation of an Nd(p) residue to Nd(s) of a polypeptide substrate. In eukaryotes, ATE1-encoded arginyl-transferases (R(D,E,C*)-transferases) conjugate Arg (R), an Nd(p) residue, to Nd(s) residues Asp (D), Glu (E), or oxidized Cys residue (C*). Ubiquitin ligases recognize the N-terminal Arg of a substrate and target the (ubiquitylated) substrate to the proteasome. In prokaryotes such as Escherichia coli, Nd(p) residues Leu (L) or Phe (F) are conjugated, by the aat-encoded Leu/Phe-transferase (L/F(K,R)-transferase), to N-terminal Arg or Lys, which are Nd(s) in prokaryotes but Nd(p) in eukaryotes. In prokaryotes, substrates bearing the Nd(p) residues Leu, Phe, Trp, or Tyr are degraded by the proteasome-like ClpAP protease. Despite enzymological similarities between eukaryotic R(D,E,C*)-transferases and prokaryotic L/F(K,R)-transferases, there is no significant sequelogy (sequence similarity) between them. We identified an aminoacyl-transferase, termed Bpt, in the human pathogen Vibrio vulnificus. Although it is a sequelog of eukaryotic R(D,E,C*)-transferases, this prokaryotic transferase exhibits a "hybrid" specificity, conjugating Nd(p) Leu to Nd(s) Asp or Glu. Another aminoacyl-transferase, termed ATEL1, of the eukaryotic pathogen Plasmodium falciparum, is a sequelog of prokaryotic L/F(K,R)-transferases (Aat), but has the specificity of eukaryotic R(D,E,C*)-transferases (ATE1). Phylogenetic analysis suggests that the substrate specificity of R-transferases arose by two distinct routes during the evolution of eukaryotes.  相似文献   
999.
Hepatic cavernous hemangioma is the most common benign tumor of the liver. Appropriate management of this tumor remains a controversial topic. We have accumulated a number of cases with successful management of local hepatic tumors. Here we report a case where we performed an ultrasound-guided percutaneous radiofrequency ablation for the treatment of a symptomatic hemangioma. A 36-year-old female patient visited Kyungpook National University Hospital because of persistent right upper abdominal pain caused by an enlarging hemangioma. After two sessions of radiofrequency ablation, the hemangioma was significantly reduced in size. After 36 months, a follow-up abdominal CT revealed remarkably diminished necrotic areas of ablated hemangioma. The size of hemangioma was decreased to almost one third of the original longitudinal diameter. The patient remains asymptomatic in regards to the hemangioma.  相似文献   
1000.
INTRODUCTION Esophageal manometry has been considered the “gold standard” test for the evaluation of esophageal motility. Esophageal manometry allows physicians to assess peri- stalsis by using informations about the shape, amplitude and duration of the…  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