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   1499篇
  免费   140篇
  国内免费   10篇
耳鼻咽喉   26篇
儿科学   62篇
妇产科学   25篇
基础医学   195篇
口腔科学   24篇
临床医学   108篇
内科学   237篇
皮肤病学   13篇
神经病学   145篇
特种医学   28篇
外科学   217篇
综合类   23篇
预防医学   83篇
眼科学   27篇
药学   125篇
中国医学   2篇
肿瘤学   309篇
  2023年   4篇
  2022年   17篇
  2021年   34篇
  2020年   28篇
  2019年   44篇
  2018年   39篇
  2017年   37篇
  2016年   41篇
  2015年   59篇
  2014年   51篇
  2013年   76篇
  2012年   93篇
  2011年   119篇
  2010年   77篇
  2009年   62篇
  2008年   86篇
  2007年   90篇
  2006年   92篇
  2005年   93篇
  2004年   83篇
  2003年   68篇
  2002年   55篇
  2001年   48篇
  2000年   33篇
  1999年   34篇
  1998年   16篇
  1997年   5篇
  1996年   5篇
  1995年   9篇
  1994年   3篇
  1993年   3篇
  1992年   14篇
  1991年   12篇
  1990年   11篇
  1989年   7篇
  1988年   8篇
  1987年   4篇
  1986年   8篇
  1985年   6篇
  1984年   4篇
  1983年   6篇
  1982年   3篇
  1981年   3篇
  1979年   10篇
  1978年   7篇
  1977年   3篇
  1973年   6篇
  1972年   6篇
  1971年   3篇
  1968年   3篇
排序方式: 共有1649条查询结果,搜索用时 18 毫秒
71.
72.
An improved formulation of the photosensitizer chlorin e6 (Ce6) in combination with the hydrophilic polymer polyvinylpyrrolidone (PVP) was investigated for its potential clinical applications in fluorescence diagnosis and photodynamic therapy (PDT) of cancer. This study reports the comparative preclinical biodistribution and efficacy of Ce6 delivered with or without PVP versus dimethyl sulfoxide (DMSO). The safety and fluorescence pharmacokinetics of Ce6-PVP in humans was also accessed. Biodistribution results showed that Ce6-PVP had higher tumor to normal tissue ratio compared to the other formulations. The sensitivity and specificity derived from the area under the receiver operating characteristics curves showed that the formulations were able to discriminate tumor from peritumoral muscle in the following order: Ce6-PVP>Ce6>Ce6-DMSO. In vitro PDT results showed that Ce6-PVP was found to induce selective phototoxicity in leukemic cells compared to peripheral mononuclear blood cells. In addition, in vivo light irradiation at 1h after Ce6-PVP was found to induce greater tumor necrosis without causing animal toxicity. In patients, preferential accumulation of Ce6-PVP was observed in angiosarcoma lesions compared to normal skin following intravenous administration. In conclusion, PVP significantly enhanced the Ce6 concentration in tumors compared with Ce6 alone and increased the therapeutic index of PDT without any side effects in animal model. No serious adverse events were observed in human as well.  相似文献   
73.
BACKGROUND: Passengers who have ventricular fibrillation aboard commercial aircraft rarely survive, owing to the delay in obtaining emergency care and defibrillation. METHODS: In 1997, a major U.S. airline began equipping its aircraft with automated external defibrillators. Flight attendants were trained in the use of the defibrillator and applied the device when passengers had a lack of consciousness, pulse, or respiration. The automated external defibrillator was also used as a monitor for other medical emergencies, generally at the direction of a passenger who was a physician. The electrocardiogram that was obtained during each use of the device was analyzed by two arrhythmia specialists for appropriateness of use. We analyzed data on all 200 instances in which the defibrillators were used between June 1, 1997, and July 15, 1999. RESULTS: Automated external defibrillators were used for 200 patients (191 on the aircraft and 9 in the terminal), including 99 with documented loss of consciousness. Electrocardiographic data were available for 185 patients. The administration of shock was advised in all 14 patients who had electrocardiographically documented ventricular fibrillation, and no shock was advised in the remaining patients (sensitivity and specificity of the defibrillator in identifying ventricular fibrillation, 100 percent). The first shock successfully defibrillated the heart in 13 patients (defibrillation was withheld in 1 case at the family's request). The rate of survival to discharge from the hospital after shock with the automated external defibrillator was 40 percent. A total of 36 patients either died or were resuscitated after cardiac arrest. No complications arose from use of the automated external defibrillator as a monitor in conscious passengers. CONCLUSIONS: The use of the automated external defibrillator aboard commercial aircraft is effective, with an excellent rate of survival to discharge from the hospital after conversion of ventricular fibrillation. There are not likely to be complications when the device is used as a monitor in the absence of ventricular fibrillation.  相似文献   
74.
Seven patients with locally far-advanced, inoperable, squamous cell cancer of the esophagus were given two cycles of concurrent radiation and chemotherapy. Each cycle consisted of 5-fluorouracil 1,000 mg/m2/day given as a continuous intravenous infusion over 96 hours, cisplatin 75 mg/m2 given as an intravenous bolus on day 1, and methotrexate 40 mg/m2 given as an intravenous bolus on days 8 and 15. Three thousand rads of radiation were given in 15 fractions between days 1 and 19. Six patients are evaluable for response. Symptomatic relief was obtained by all six and was complete in 4. Five patients achieved a complete response, and two remain alive and disease free. Five of the six evaluable patients survived for at least 12 months. Aggressive chemoradiotherapy may result in significant survival prolongation and symptomatic palliation in this poor-prognosis subset of patients with esophageal cancer.  相似文献   
75.
PURPOSE:To describe postoperative endophthalmitis caused by sequestered Acinetobacter calcoaceticus.METHOD:Case report. A 40-year-old woman developed recurrence of inflammation after extracapsular cataract extraction with intraocular lens (IOL) implantation. At last recurrence, the capsular bag was studded with white deposits. Intraocular lens was removed along with capsular bag during pars plana vitrectomy.RESULTS:The capsular bag, when cultured, grew A calcoaceticus. The media remained clear with no evidence of recurrence of infection over a 3-month follow-up. CONCLUSION:Postoperative endophthalmitis similar to that caused by sequestered Propionibacterium acnes can be caused by A calcoaceticus.  相似文献   
76.
External resorption is sequelae of necrotic periodontal membrane over a large area of root following an injury to the tooth. This usually occurs after severe dental injuries such as intrusion, severe luxations or exarticulation injuries complicated by a prolonged extra oral period. This case report presents a clinical and radiographic follow up (13 months) of treatment of inflammatory external root resorption on maxillary central incisor using Vitapex. Gradual healing of resorption was observed radiographically with no tenderness or pathological mobility.  相似文献   
77.
Mucinous cancers of the breast are distinguished histologically by their abundant pools of mucin and low degree of nuclear pleomorphism. Relative to the more common breast cancers of no distinctive type (ductal carcinoma), mucinous cancers have a relatively favorable prognosis. In a study of chromosomal changes in mucinous cancers, we evaluated the extent of loss of heterozygosity (LOH) at chromosomal regions commonly deleted in usual infiltrating ductal carcinoma, including markers on chromosomal arms 1p, 1q, 3p, 6q, 8p, 9p, 11p, 11q, 13q, 16q, 17p, and 17q. Remarkably, we found an average frequency of LOH of only 1.9 of these 12 chromosomal arms in 18 cases of mucinous carcinoma, compared to an average frequency of LOH of 6.4 of these same chromosomal arms in cases of infiltrating ductal cancer. In three of the 18 cases of mucinous carcinoma studied, including one case with regional lymph node metastases, no LOH was seen at any of the 12 chromosomal regions studied. We considered the possibility of other chromosomal loci being more commonly affected in mucinous cancers and conducted comparative genomic hybridization on six of the cases. These studies demonstrated a low overall frequency of genomic copy number changes (mean of 3.1 changes per case) and failed to reveal any other chromosomal locus with frequent losses that had not been evaluated by microsatellite analysis. Together, these data indicate that mucinous cancers of the breast do not have the extensive genomic alterations that are typically found in more common variants of breast cancer. Thus, mucinous cancers most likely have less genetic instability than most other forms of breast cancer and the molecular pathogenesis of this form of breast cancer is likely to be substantially different than that of usual ductal breast cancer.  相似文献   
78.
Lysophosphatidic acid induces glycodelin gene expression in cancer cells   总被引:3,自引:0,他引:3  
Glycodelin is a glycoprotein that has been suggested to be important in normal pregnancy and in malignancy. The regulation of its synthesis has not been studied. In this study, we report the induction of glycodelin gene expression by lysophosphatidic acid (LPA). We studied the effect of LPA (5, 10 and 25 microM) on glycodelin production in breast (MDA-MB-231), cervical (Hela), endometrial (RL-95), ovarian cancer (OVCAR-3) and erythroleukemia (K562) cells. There was a dose-dependent (5-25 microM) induction of glycodelin gene and protein expression in these cell types. LPA is a mimic of phorbol myristate acetate (PMA) action and is found to be elevated in high concentrations in the serum of cancer subjects. As glycodelin is an angiogenic protein with a potential immunosuppressive role, control of LPA synthesis might offer a potential target for intervention.  相似文献   
79.
80.
The pathological distinction between malignant pleural mesothelioma (MPM)and adenocarcinoma (ADCA) of the lung can be cumbersome using established methods. We propose that a simple technique, based on the expression levels of a small number of genes, can be useful in the early and accurate diagnosis of MPM and lung cancer. This method is designed to accurately distinguish between genetically disparate tissues using gene expression ratios and rationally chosen thresholds. Here we have tested the fidelity of ratio-based diagnosis in differentiating between MPM and lung cancer in 181 tissue samples (31 MPM and 150 ADCA). A training set of 32 samples (16 MPM and 16 ADCA) was used to identify pairs of genes with highly significant, inversely correlated expression levels to form a total of 15 diagnostic ratios using expression profiling data. Any single ratio of the 15 examined was at least 90% accurate in predicting diagnosis for the remaining 149 samples (e.g., test set). We then examined (in the test set) the accuracy of multiple ratios combined to form a simple diagnostic tool. Using two and three expression ratios, we found that the differential diagnoses of MPM and lung ADCA were 95% and 99% accurate, respectively. We propose that using gene expression ratios is an accurate and inexpensive technique with direct clinical applicability for distinguishing between MPM and lung cancer. Furthermore, we provide evidence suggesting that this technique can be equally accurate in other clinical scenarios.  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