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   6292篇
  免费   356篇
  国内免费   48篇
耳鼻咽喉   69篇
儿科学   197篇
妇产科学   45篇
基础医学   711篇
口腔科学   109篇
临床医学   433篇
内科学   1666篇
皮肤病学   96篇
神经病学   426篇
特种医学   417篇
外科学   1095篇
综合类   64篇
一般理论   1篇
预防医学   222篇
眼科学   185篇
药学   233篇
  1篇
中国医学   20篇
肿瘤学   706篇
  2024年   34篇
  2023年   92篇
  2022年   160篇
  2021年   282篇
  2020年   155篇
  2019年   166篇
  2018年   249篇
  2017年   167篇
  2016年   185篇
  2015年   182篇
  2014年   237篇
  2013年   307篇
  2012年   430篇
  2011年   443篇
  2010年   233篇
  2009年   192篇
  2008年   344篇
  2007年   352篇
  2006年   299篇
  2005年   336篇
  2004年   336篇
  2003年   250篇
  2002年   243篇
  2001年   95篇
  2000年   82篇
  1999年   65篇
  1998年   57篇
  1997年   51篇
  1996年   40篇
  1995年   28篇
  1994年   30篇
  1993年   21篇
  1992年   59篇
  1991年   46篇
  1990年   48篇
  1989年   51篇
  1988年   48篇
  1987年   44篇
  1986年   37篇
  1985年   34篇
  1984年   23篇
  1983年   20篇
  1982年   15篇
  1981年   14篇
  1980年   10篇
  1979年   14篇
  1975年   10篇
  1973年   10篇
  1971年   9篇
  1970年   12篇
排序方式: 共有6696条查询结果,搜索用时 15 毫秒
61.
BACKGROUND CONTEXT: Although posterior lumbar interbody fusion (PLIF) for degenerative lumbar diseases is routine, there are few reports on double-level PLIF. PURPOSE: To evaluate the clinical outcomes of double-level PLIF. STUDY DESIGN/SETTING: A retrospective study of operated cases in Gifu, Japan. PATIENT SAMPLE: Nineteen patients (8 men and 11 women, 59.5+/-10.2 years) who underwent double-level PLIF between 1996 and 2001. OUTCOME MEASURES: Operation time, blood loss, complications, the Japanese Orthopaedic Association (JOA) score for back pain and lumbar sagittal alignment were evaluated. METHODS: Patients were examined retrospectively at follow-ups of 3.6+/-1.7 years. Primary diseases were spondylolisthesis, spinal canal stenosis, degenerative scoliosis and herniated intervertebral disc. Fusion areas were L3 to L5 in 15 cases and L4 to S1 in 4 cases. RESULTS: The mean JOA score increased from an initial score of 12.9+/-3.5 to 21.3+/-4.9 at the final follow-up. There was a positive correlation (R=0.718, p<.001) between the increase in lordotic angle and the increase in the JOA score. Several parameters suggested that the surgical invasiveness was not minimal. CONCLUSION: Double-level PLIF provided satisfactory results and preserved lumbar spine lordosis.  相似文献   
62.
The congenital absence of the portal vein (CAPV) is a rare venous malformation in which mesenteric venous blood drains directly into the systemic circulation. Liver transplantation (OLT) may be indicated for patients with symptomatic CAPV refractory to medical treatment, especially due to hyperammonemia, portosystemic encephalopathy, hepatopulmonary syndrome, or hepatic tumors. Because portal hypertension and collateral circulation do not occur with CAPV, significant splanchnic congestion may occur when the portocaval shunt is totally clamped during portal vein (PV) reconstruction in OLT. This phenomenon results in severe bowel edema and hemodynamic instability, which negatively impact the patient's condition and postoperative recovery. We have successfully reconstructed the PV in living donor liver transplantation (LDLT) using a venous interposition graft, which was anastomosed end-to-side to the portocaval shunt by a partial side-clamp, using a patent round ligament of the liver, which was anastomosed end-to-end to the graft PV with preservation of both the portal and caval blood flows. Owing to the differences in anatomy among patients, at LDLT for CAPV liver transplant surgeons should seek to preserve both portal and caval blood flows.  相似文献   
63.
Purpose  We conducted a double-blind placebo-controlled study to investigate the effects of the intraoperative intravenous infusion of adenosine 5′-triphosphate (ATP) on intraoperative hemodynamics and postoperative pain in patients undergoing major orofacial surgery. Methods  Thirty patients (age, 16–42 years; 16 males/14 females) scheduled for sagittal split ramus osteotomy were assigned in a double-blind fashion to receive intraoperative intravenous infusion of ATP (n = 15) or saline (n = 15). Anesthesia was induced and maintained with propofol, fentanyl, and vecuronium. Local anesthesia was added for intraoperative analgesia. In the ATP group, ATP was infused at a rate of 160 μg·kg−1·min−1 throughout surgery. Postoperative pain was managed with intravenous patient-controlled analgesia (PCA) with morphine. The intensity of postoperative pain was assessed with a verbal numeric rating scale (NRS). Morphine consumption was also assessed. Results  There were no differences in demographic, anesthetic, and surgical data between the ATP and placebo groups. Intraoperatively, ATP effectively suppressed responses of blood pressure and heart rate to painful surgical stimuli. There were no differences in postoperative NRS scores between the two groups. However, postoperative morphine consumption was significantly less in the ATP group, compared with the placebo group, throughout the 72-h postoperative observation period. Cumulative morphine consumption for 72 h postoperatively was 47% less with ATP, compared with placebo. No adverse effect of ATP was observed. Conclusion  Our data suggest that intraoperative ATP infusion can blunt hemodynamic responses to surgical stimuli and produce prolonged analgesia in patients undergoing major orofacial surgery.  相似文献   
64.
Purpose  The aim of this study was to evaluate the indications for pulmonary resection (lobectomy) in patients with increased total pulmonary vascular resistance (TPVR) during a preoperative unilateral pulmonary artery occlusion (UPAO) test. According to our previous report, the feasibility of performing lobectomy in patients with a high risk of cardiopulmonary complications is determined on the basis of the increase in TPVR after 15 min of obstruction during the UPAO test (occluded TPVR). Methods  A total of 19 high-risk [occluded TPVR ≥700 dynes/s/cm−5/m2 (dynes)] patients who underwent lobectomy or pneumonectomy were studied and a detailed analysis of postoperative cardiopulmonary complications was performed. The subjects were divided into four groups based on the occluded TPVR (700–799 dynes, 800–899 dynes, 900–999 dynes, or ≥1000 dynes) to compare the incidence of postoperative complications. Results  Two patients died after surgery. One of them had an occluded TPVR >1000 dynes and died 313 days after right upper lobectomy; the other had an occluded TPVR of 783 dynes and died 20 days after right pneumonectomy. Postoperative cardiopulmonary complications occurred in 6 of 19 patients (31.6%), and all three patients with an occluded TPVR ≥900 dynes developed cardiopulmonary complications. Conclusion  Limited surgery should be performed in patients with an occluded TPVR ≥900 dynes.  相似文献   
65.
Sato Y  Honda Y  Iwamoto J  Kanoko T  Satoh K 《BONE》2005,36(4):721-726
Risk of hip fractures in stroke patients is higher than that in a reference population. Hyperhomocysteinemia is regarded as a risk factor for ischemic stroke. The high prevalence of osteoporosis among patients with homocystinuria suggests that hyperhomocysteine may also increase the risk of fractures. To determine the association between homocysteine concentration and the risk of hip fractures, we studied a cohort of stroke patients with hemiplegia. Age-adjusted incidence rates of a hip fracture were calculated for quartiles of homocysteine concentrations. Cox proportional-hazard regression was used to calculate hazard ratios for quartiles of homocysteine levels. The initial enrolment of 433 hemiplegic patients with ischemic stroke, older than 65 years old, were followed for up to 10 years. The mean plasma homocysteine concentration at the enrolment was 14.1 +/- 5.2 micromol/L. There were 33 hip fractures among men and 46 among women during the mean follow-up period of 9.0 years. The age-adjusted incidence rates per 1000 person-years for hip fractures increased almost linearly from 2.89 in the lowest to 27.87 in the highest quartiles of homocysteine levels. We conclude that hyperhomocysteinemia is one of the risk factors for hip fractures in stroke patients.  相似文献   
66.
BACKGROUND: Parathyroid hormone-related protein (PTHrP) is produced by cancer cells and has been suggested to be responsible for malignancy-associated hypercalcemia and osteolysis after bone metatsases. Therefore, PTHrP is a promising target in the treatment of metastatic prostate cancer. METHODS: Seven PTHrP-derived peptides were prepared based on the HLA-A2 binding motif. These peptide candidates were screened by their ability to induce peptide-specific cytotoxic T lymphocytes (CTLs), and their ability to be recognized by immunoglobulin G (IgG). RESULTS: Both the PTHrP59-67 and PTHrP42-51 peptides were found to efficiently induce peptide-specific CTLs from peripheral blood mononuclear cells of HLA-A2+ prostate cancer patients with several HLA-A2 subtypes. These CTLs showed HLA-A2-restricted cytotoxicity toward prostate cancer cells. IgG reactive to the PTHrP42-51 peptide was frequently detected in prostate cancer patients. CONCLUSIONS: These results indicate that these two new PTHrP peptides will be useful in the peptide-based immunotherapy of HLA-A2+ prostate cancer patients, especially those with bone metastases.  相似文献   
67.
OBJECTIVE: Distinction of lymph node stations is one of the most crucial topics still not entirely resolved by many lung cancer surgeons. The nodes around the junction of the hilum and mediastinum are key points at issue. We examined the spread pattern of lymph node metastases, investigated the prognosis according to the level of the involved nodes, and conclusively analyzed the border between N1 and N2 stations. METHODS: We reviewed the records of 604 consecutive patients who underwent complete resection for non-small cell lung carcinoma of the lower lobe. RESULTS: There were 390 patients (64.6%) with N0 disease, 127 (21.0%) with N1, and 87 (14.4%) with N2. Whereas 11.3% of patients with right N2 disease had skip metastases limited to the subcarinal nodes, 32.6% of patients with left N2 disease had skip metastases, of which 64.2% had involvement of N2 station nodes, except the subcarinal ones. The overall 5-year survivals of patients with N0, N1, and N2 disease were 71.0%, 50.8%, and 16.7%, respectively (N0 vs N1 P = .0001, N1 vs N2, P < .0001). Although there were no significant differences in survival according to the side of the tumor among patients with N0 or N1 disease, patients with a left N2 tumor had a worse prognosis than those with a right N2 tumor (P = .0387). The overall 5-year survivals of patients with N0, intralobar N1, hilar N1, lower mediastinal N2, and upper mediastinal N2 disease were 71.0%, 60.1%, 38.8%, 24.8%, and 0%, respectively. Significant differences were observed between intralobar N1 and hilar N1 disease ( P = .0489), hilar N1 and lower mediastinal N2 disease (P = .0158), and lower and upper mediastinal N2 disease (P = .0446). Also, the 5-year survivals of patients with involvement up to station 11, up to station 10, and up to station 7 were 41.4%, 37.9% and 37.7%, respectively (difference not significant). CONCLUSIONS: N1 and N2 diseases appeared as a combination of subgroups: intralobar N1 disease, hilar N1 disease, lower mediastinal N2 disease, and upper mediastinal N2 disease. Interestingly, the survivals of patients with involvement up to interlobar nodes (station 11), main bronchus nodes (station 10), and subcarinal nodes (station 7) were identical. These data constitute the basis for a larger investigation to develop a lymph node map in lung cancer.  相似文献   
68.
BACKGROUND: Carnitine is applied to ameliorate ischemia-reperfusion (I/R) injury of several organs. However, application to hepatic I/R injury is not frequently reported. The aim of this study was to elucidate the effect of exogenous carnitine administration to ameliorate the warm hepatic I/R injury. MATERIALS AND METHODS: Male Wistar rats were divided into two groups, a carnitine group (Car);100 mg/kg of l-carnitine administration and a control group (C); vehicle administration. Thirty minutes after administration, the left hepatic lobes were given 60-min ischemia and then reperfused. Plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH), tumor necrosis factor (TNF)-alpha, and lipoperoxides (LPO) were measured. Hepatic adenosine triphosphate (ATP) concentration was also measured. The hepatic blood flow was estimated using a Laser Doppler. The presence of apoptosis in the livers was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. RESULTS: In group Car, the blood flow of the left hepatic lobes was better recovered during the reperfusion period than in group C (P < 0.0001). Plasma levels of ALT, AST, GLDH, and TNF-alpha at 1 h after reperfusion were not significantly different between the groups. Although there were no statistical significances, ALT, AST, and TNF-alpha levels in group Car at 24 h after reperfusion tended to be higher than in group C. Plasma LPO levels were not different between the two groups. Also hepatic ATP concentration was not different between the two groups. TUNEL positive liver cells were visible only in group Car at 24 h after reperfusion, but not in the controls. CONCLUSIONS: Although carnitine administration improved the hepatic blood flow during the reperfusion period, we could not demonstrate a protective effect to the hepatic warm I/R injury.  相似文献   
69.
Kobayashi S  Ohnuma K  Uchiyama M  Iino K  Iwata S  Dang NH  Morimoto C 《Blood》2004,103(3):1002-1010
CD26 is a T-cell activation antigen that contains dipeptidyl peptidase IV activity and binds adenosine deaminase. Recent work showed that specialized membrane microdomains, also known as lipid rafts, play a key role in T-cell signaling. In this study, we investigate the role of CD26 in cord blood T-cell activation and signal transduction. We demonstrated that different expression levels of CD26 were observed between cord blood T cells (CBTCs) and peripheral blood T cells (PBTCs) and that CD26(+)CD45RA(+) CBTCs were different compared with CD26(+)CD45RA(+) PBTCs. Moreover, the comitogenic effect of CD26 was not as pronounced in CBTCs as in PBTCs. We also showed that CD26 cross-linking induced less phosphorylation of T-cell receptor-signaling molecules, lymphoid T-cell protein tyrosine kinase (Lck), zeta-associated protein 70 (ZAP-70), T-cell receptor zeta (TCRzeta), and linker for activator of T cells (LAT) in CBTCs than in PBTCs. Furthermore, CD26 molecules associated with CD45RA molecules outside lipid rafts in CBTCs. Our results suggest that strong physical linkage of CD26 with CD45RA outside lipid rafts may be responsible for the attenuation of T-cell activation signaling through CD26, which may be responsible for immature immune response and the low incidence of severe graft-versus-host disease in cord blood transplantation.  相似文献   
70.
Purpose To report the outcome of transcorneal electrical stimulation (TES) of the visual system on long-standing retinal artery occlusion (RAO). Design Open labeled, case series. Patients and methods Two patients with central RAO (15 and 33 months respectively) and one with branch RAO (26 months) underwent TES therapy. Subjective and objective ophthalmological evaluations were performed before and after the TES. The ages of the patients were 38, 49, and 63 years. The TES (20 Hz biphasic pulses, 30 minutes, up to 1100 uA) was delivered by a bipolar contact lens electrode once a month for 3 months. Perimetric and/or electrophysiological examinations were performed as outcome measures. Results The visual acuity improved by more than 0.2 logMAR units in two cases, and the visual fields were improved in all three cases. The multifocal ERGs which had been reduced in the loci corresponding to the ischemic retinal area were improved after the treatment in two cases. Neither ocular nor systemic adverse effects were observed except for transient superficial keratitis. Conclusions TES of the retina can improve retinal function in eyes with long-standing RAOs. None of the authors have any financial or proprietary interest in any material or methods mentioned. This study was supported by Researches on Sensory and Communicative Disorders from the Ministry of Health, Labor, and Welfare, Japan.  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