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   4798篇
  免费   234篇
  国内免费   20篇
耳鼻咽喉   51篇
儿科学   88篇
妇产科学   18篇
基础医学   451篇
口腔科学   78篇
临床医学   293篇
内科学   1366篇
皮肤病学   236篇
神经病学   253篇
特种医学   135篇
外科学   919篇
综合类   28篇
预防医学   121篇
眼科学   64篇
药学   309篇
中国医学   4篇
肿瘤学   638篇
  2023年   25篇
  2022年   68篇
  2021年   99篇
  2020年   51篇
  2019年   75篇
  2018年   65篇
  2017年   56篇
  2016年   81篇
  2015年   93篇
  2014年   86篇
  2013年   117篇
  2012年   215篇
  2011年   206篇
  2010年   115篇
  2009年   119篇
  2008年   185篇
  2007年   166篇
  2006年   190篇
  2005年   191篇
  2004年   205篇
  2003年   205篇
  2002年   203篇
  2001年   186篇
  2000年   211篇
  1999年   158篇
  1998年   75篇
  1997年   63篇
  1996年   50篇
  1995年   56篇
  1994年   60篇
  1993年   43篇
  1992年   102篇
  1991年   109篇
  1990年   95篇
  1989年   110篇
  1988年   99篇
  1987年   85篇
  1986年   113篇
  1985年   87篇
  1984年   51篇
  1983年   58篇
  1982年   31篇
  1979年   39篇
  1978年   22篇
  1977年   44篇
  1975年   27篇
  1972年   29篇
  1971年   30篇
  1970年   32篇
  1969年   21篇
排序方式: 共有5052条查询结果,搜索用时 31 毫秒
61.
Background. Exact clinical staging before treatment of esophageal cancer has become increasingly important in the evaluation and comparison of the results of different treatment modalities, including surgery, chemotherapy, and radiotherapy.

Methods. The accuracy of preoperative tumor staging by using an esophagography, esophagoscopy, percutaneous and endoscopic ultrasonography, and computed tomography was assessed in 224 patients with resectable esophageal cancer. The results of tumor staging by these tests were compared prospectively with the pathologic stage of the esophagectomy specimens with respect to the T and N categories defined by the International Union Against Cancer TNM classification.

Results. For the T category, the overall accuracy was 80%. For the N category, overall accuracy was 72%, with a sensitivity of 78%, a specificity of 60%, and a positive predictive value of 78%. Overall, the accuracy of stage grouping was 56%.

Conclusions. Either the T or N categories can be predicted reliably by clinical staging techniques. However, the preoperative stage grouping might not be valid in resectable, localized esophageal cancer.  相似文献   

62.
To evaluate the effect of interferon-γ-genetransduced cells, DS mice were inoculated into their footpads with syngeneic mammary adenocarcinoma SC42 admixed with interferon-γ producing mammary adenocarcinoma SC115Kγ, which had been established by an interferon-γ-gene transduction in another syngeneic mammary adenocarcinoma SC115 using retroviral vectors. These mice rejected both tumor cells and developed resistance to subsequent challenges with either SC115 or SC42 cells inoculated into their opposite posterior footpads. These results thus indicate that systemic immunological memory to each of the independent tumor cell lines developed in these mice. Although the SC42 cells admixed with irradiated SC115Kγ cells were rejected by these mice, the SC42 cells admixed with irradiated SC115neoR, in which the neo-gene had been transduced, were observed to proliferate. Tumor rejection was reversed by an in vivo administration of anti-interferon-γ antibody, thus suggesting that locally produced interferon-γ plays an important role in tumor elimination and immunological memory induction. In conclusion, interferon-γ-gene-transduced tumor cells are therefore considered to have a therapeutic potential for other types of malignant tumor cell lines.  相似文献   
63.
BACKGROUND: Although bursting pressure and tensile strength have long been measured to evaluate anastomotic techniques, it has yet to be clarified whether or not they are correlated, what implications they have, and which should be used as a gold standard. MATERIAL AND METHODS: Using an experimental model to estimate pressure and tension in the same colonic anastomosis, the following variables were measured in 48 rats between days 0 and 14: bursting pressure (BP); minimal tensile strength (MITS) necessary to break a part of the anastomosis, and maximal tensile strength (MATS) needed to disrupt the whole anastomosis. Also, circulatory wall tension (CWT) was derived from BP and the anastomotic circumference (AC), and longitudinal wall tension (LWT) from MITS and AC. These variables were compared using correlation and regression analysis. RESULTS: During the lag phase (days < or = 4) there was poor correlation between pressure-related and tension-related variables whereas highly significant correlations were noted in the subsequent fibroplastic phase (day > or = 5). It was shown by regression lines that positive MITS and MATS were expected when BP was zero. CONCLUSION: Contrary to the previous assumption, no correlation was found between BP and tensile strength in the critical postoperative period. Based on our present and previous studies, measurement of MITS is recommended to evaluate the healing of colonic anastomosis.  相似文献   
64.
BACKGROUND AND AIM: It has been reported that a coronary event is the leading cause of mortality in HD patients. The aim of this study was to examine and compare prospectively the effect of aging in relation to the in-hospital and the long-term outcome in HD patients with or without revascularization therapy who had experienced a coronary event. STUDY PATIENTS AND METHODS: Seventy consecutive HD patients with coronary events (9 AMI, 48 AP, and 13 CHF) were registered in this study and 69 patients underwent CAG. Patients were classified into elderly (> or = 65, n = 33) and younger (< 65, n = 37) groups based on their ages at the time of the events. Forty-six patients (21 vs 25) underwent initial coronary revascularization therapy. We followed 70 HD patients with coronary events for a mean period of 31 +/- 21 months (range: 1 day to 77 months). RESULTS: A level of 64% of the elderly group and 41% of the younger group experienced coronary events within the first year of HD. The diseased vessels (2.2 vs 1.9 per patient) and stenotic lesions (2.8 vs 2.5 pre patients) were not significantly different between the two groups. The 70-month survival rate was significantly lower (21% vs 65%, p = 0.0423) in the elderly group than in the younger group. The complicated rate of stroke after a major event was significantly higher (14 vs 4, p = 0.0025) in the elderly group than in the younger group. Moreover 21 elderly patients (11 cardiac death, 5 stroke, 4 cancer) and 9 younger patients (8 cardiac death, 1 stroke) died during the 70-month follow-up period. CONCLUSIONS: Coronary events were most frequent in the first year of HD. Long-term survival rate was significantly lower in elderly patients than in younger patients. Cardiac death was the most common cause of death in both groups regardless of performing coronary revascularization. Death due to stroke and cancer was also more common in elderly patients.  相似文献   
65.
High-dose intraoperative radiotherapy for unresectable pancreatic cancer   总被引:9,自引:0,他引:9  
PURPOSE: The results of high-dose intraoperative radiotherapy (IORT) and/or external beam radiotherapy (EBRT) for unresectable pancreatic cancer were analyzed to evaluate the possible advantages of IORT in combination with EBRT. METHODS AND MATERIALS: Between 1983 and 1993, 115 patients with unresectable adenocarcinoma of the pancreas (53 with non-Stage IV disease and 62 with Stage IV disease) were treated with EBRT + IORT (55 patients), EBRT alone (44 patients), or IORT alone (16 patients). In non-Stage IV patients, the use of EBRT alone was due to the unavailability of IORT and the use of IORT alone was due to refusal of EBRT. The IORT dose was 30-33 Gy and the EBRT dose was 40-60 Gy. A historical control group comprised of 101 patients undergoing palliative surgery alone was also analyzed. RESULTS: Both non-Stage IV and Stage IV patients receiving EBRT with or without IORT had a better prognosis than the nonirradiated historical controls. Among non-Stage IV patients, the median survival of the EBRT + IORT group (8.5 months) and the EBRT group (8 months) was similar, although survival from 12 to 18 months was higher in the former group (38% vs. 10% at 12 months, p = 0.018, and 19% vs. 0% at 18 months, p = 0.023). In Stage IV patients, the prognosis was not influenced by the type of radiotherapy. Multivariate analysis revealed that a pretreatment carbohydrate antigen (CA) 19-9 level < 1000 U/ml was associated with better survival. In non-Stage IV patients with a CA 19-9 level < 1000 U/ ml, EBRT + IORT appeared to produce a better survival than EBRT alone (p = 0.047). This was supported by multivariate analysis. CONCLUSION: High-dose IORT + EBRT may be more effective than EBRT alone in patients with unresectable but localized pancreatic cancer and a low CA 19-9 level.  相似文献   
66.
We have already reported the antitumour effect of hydroxyapatite (HAP) containing anticancer drugs. In this study, we found an increased temperature effect around HAP particle(s) in an agar phantom in comparison with other areas when a Thermotron-RF8 (RF generator) was used for heating. Furthermore, it was revealed that the quantity of doxorubicin hydrochloride (DOX) released from HAP containing the drug (DOX-HAP complex) was increased by raising the temperature. These results indicated that the antitumor effect of the DOX-HAP complex + hyperthermia system was greater than that of either the DOX-HAP complex or hyperthermia system alone.  相似文献   
67.
An adult male was found dead beneath a pool of sewage in the pump room of a fish market. Autopsy revealed the cause of death to be suffocation after aspirating sewage into the respiratory tract. Since hydrogen sulfide gas was detected in the atmosphere at the scene of the accident, gas poisoning was suspected and toxicological analysis of sulfides in body tissues was performed. The concentrations of sulfides in the blood, lung and kidney were 0.95 mol/ml, 0.22 and 0.38 mol/g, respectively. These values were remarkably higher than those in previously reported cases involving exposure to hydrogen sulfide gas. Therefore, oral intake of sulfides was assumed and the distribution of sulfides in tissues following oral administration of sodium sulfide solution was examined by means of animal experiments using rats. The concentration of sulfides in the blood from rats following oral intake was much higher than that seen following gas exposure. Based on these results, we concluded that the victim had been exposed to hydrogen sulfide gas and had then collapse into a pool of sewage containing sulfides. The sulfides which were distributed throughout the body tissues had mainly issued from the alimentary tract prior to death by drowning.  相似文献   
68.
We found that neuropsin, an extracellular matrix serine protease, has a regulatory effect on Schaffer-collateral long-term potentiation (LTP) in the mouse hippocampus. Bath application of 1-170 nM recombinant neuropsin modulated early phase LTP in the Schaffer-collateral pathway with a 'bell-shape' dose-response curve. The maximum enhancing activity (134% of control LTP) was found at approximately 2.5 nM. Bath application of a neutralizing antibody against neuropsin in the hippocampal slice resulted in a marked inhibition of the tetanus-induced early phase of LTP. The in vivo continuous intraventricular infusion of an antisense oligonucleotide against neuropsin significantly reduced the amplitude of the tetanus-induced early phase of LTP in vitro. Neuropsin did not directly change the N-methyl D-aspartate (NMDA) current. Thus, neuropsin appears to act as a regulatory molecule in the early phase of LTP via its proteolytic function on extracellular matrix rather than affecting NMDA receptor-mediated calcium increase.  相似文献   
69.
The intravenous secretin injection test (secretin test) has been used for the differential diagnosis of gastrinoma. In this study we report that the intraoperative secretin test (IOS test) is also useful for determining the extent of curability in patients with Zollinger-Ellison syndrome (ZES). Twelve patients with ZES underwent surgical exploration and the IOS test. The results of the IOS test were obtained by rapid radioimmunoassay of the serum gastrin level (IRG) within 60 minutes. The test was diagnosed as negative when the maximum increase of serum IRG was less than 80 pg/ml and also less than 20% of the basal serum IRG level. Three of the twelve patients underwent pancreatoduodenectomy (PD), and two patients underwent distal pancreatectomy. Extirpation of duodenal tumors with dissection of regional lymph nodes was performed in seven patients. In two of the seven patients the IOS test remained positive after extirpation of the duodenal tumors and the dissection of regional lymph nodes. In one patient PD was performed on the basis of the positive results, and the IOS test became negative after PD. In the other patient, two tiny metastatic liver tumors were identified and were resected, but the IOS test did not become negative. We closed the abdomen in 11 patients when we obtained negative results from the IOS test. The results of the IOS test were almost identical to the data obtained by the standard assay postoperatively. The serum IRG levels of all but one patient fell to the normal level, and the secretin test became negative postoperatively. The IOS test is thus useful and indispensable for curative resection of microgastrinomas in patients with ZES.  相似文献   
70.
We report here two cases of MRSA sepsis following craniotomy. In case 1, a petroclival meningioma was subtotally removed and lumbar drainage was inserted postoperatively to prevent cerebrospinal fluid leakage. Ventriculo-peritoneal shunt was performed after meningitis was treated with vancomycin and panipenem/betamipron. Two weeks after the procedure, the patient revealed continuous spiking fevers related to MRSA sepsis, which did not improve with vancomycin and arbekacin administration. The focus of infection was found by scintigraphy and CT by 67Ga to be spondylo-diskitis at the level of L2-L3. The lesion was removed and bone from the iliac crest grafted. In case 2, seven days after surgery for multiple meningioma, the patient exhibited spiking fevers and swelling in the left leg. The central venous catheter was removed from the left femoral vein and MRSA was found from blood culture. The patient was treated with arbekacin (200 mg/day). Venous thrombosis diagnosed by CT was treated with heparin. Symptoms related to the infection and laboratory data did not improve because the concentration of arbekacin in the blood did not reach an effective level. The symptoms markedly improved when the dose of arbekacin was doubled (400 mg/day).  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