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   435篇
  免费   53篇
  国内免费   2篇
耳鼻咽喉   9篇
儿科学   3篇
妇产科学   2篇
基础医学   37篇
口腔科学   4篇
临床医学   30篇
内科学   101篇
皮肤病学   1篇
神经病学   50篇
特种医学   19篇
外科学   60篇
综合类   15篇
预防医学   56篇
眼科学   5篇
药学   11篇
肿瘤学   87篇
  2019年   5篇
  2018年   6篇
  2017年   3篇
  2016年   11篇
  2015年   4篇
  2014年   7篇
  2013年   14篇
  2012年   19篇
  2011年   22篇
  2010年   9篇
  2009年   13篇
  2008年   23篇
  2007年   17篇
  2006年   34篇
  2005年   32篇
  2004年   40篇
  2003年   18篇
  2002年   26篇
  2001年   10篇
  2000年   11篇
  1999年   7篇
  1997年   2篇
  1994年   4篇
  1993年   3篇
  1992年   4篇
  1991年   6篇
  1990年   8篇
  1989年   9篇
  1988年   8篇
  1987年   9篇
  1986年   5篇
  1985年   8篇
  1984年   6篇
  1983年   9篇
  1982年   7篇
  1981年   6篇
  1980年   3篇
  1979年   5篇
  1978年   9篇
  1976年   3篇
  1975年   3篇
  1974年   2篇
  1973年   4篇
  1972年   4篇
  1971年   2篇
  1970年   7篇
  1968年   3篇
  1967年   6篇
  1965年   2篇
  1962年   4篇
排序方式: 共有490条查询结果,搜索用时 15 毫秒
431.
Dopamine can be autoxidized to superoxides and quinones. Superoxides can form hydroxyl radicals that are highly reactive with lipids, proteins and DNA leading to neuronal damage and cell death. We used a clonal catecholaminergic cell line (CATH.a) derived from the central nervous system to evaluate the effects of dopamine on cell death, lipid peroxidation and DNA base damage. Dopamine produces cell death in CATH.a cells and this is associated with an increase in annexin binding, which is an early indicator of apoptosis. Incubation of CATH.a cells with deferoximine, an iron chealator, partially antagonizes dopamine-induced cell death. In CATH.a cells, dopamine produces an increase in both lipid peroxidation, as measured by cis-parinaric acid fluorescence, and DNA oxidative base damage, as measured by 8-hydroxy-2'-deoxyguanosine formation. Cell death was inhibited 84-92% by the hydrophilic antioxidants, dithiothreitol, L-cysteine, and N-acetylcysteine. The lipophilic vitamins, retinol and vitamin E and the vitamin E analog, Trolox, inhibited dopamine-induced cell death by 18-33%. The lipophilic antioxidants probucol, propyl glycol and butylated hydroxyanisone had no inhibitory effect on dopamine-induced cell death. These data suggest that damage to DNA and lipids may be partially responsible for dopamine-induced cell death in CATH.a cells.  相似文献   
432.
OBJECTIVES: Preclinical observations that selective cyclooxygenase-2 inhibitors enhance in vitro cell radiosensitivity and in vivo tumor radioresponse led to clinical trials testing therapeutic efficacy of these agents. Our study was designed to determine whether the COX-2 inhibitor celecoxib could be safely administered in doses within those approved by the Food and Drug Administration when used concurrently with thoracic radiotherapy in patients with poor prognosis non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: The trial consisted of three cohorts of patients: (a) locally advanced NSCLC with obstructive pneumonia, hemoptysis, and/or minimal metastatic disease treated with 45 Gy in 15 fractions; (b) medically inoperable early-stage NSCLC treated with definitive radiation of 66 Gy in 33 fractions; and (c) patients who received induction chemotherapy but who were not eligible for concurrent chemoradiotherapy trials. These patients received 63 Gy in 35 fractions. Celecoxib was administered p.o. on a daily basis 5 days before and throughout the course of radiotherapy. Celecoxib doses were escalated from 200, 400, 600, to 800 mg/d given in two equally divided doses. Two to eight patients of each cohort were assigned to each dose level of celecoxib. RESULTS: Forty-seven patients were enrolled in this protocol (19 in cohort I, 22 in cohort II, and 6 in cohort III). The main toxicities were grades 1 and 2 nausea and esophagitis, and they were independent of the dose of celecoxib or radiotherapy schedule. Only two patients in group II developed grade 3 pneumonitis 1 month after treatment, one on 200 mg, and the other on 400 mg celecoxib. Celecoxib-related toxicity developed in 3 of 47 patients: an uncontrolled hypertension in one patient on 800 mg celecoxib and hemorrhagic episodes in 2 patients (shoulder hematoma in one and hemoptysis in the other) on 200 mg celecoxib who were on warfarin for other medical reasons. Of 37 patients evaluable for tumor response, 14 had complete response, 13 partial responses, and 10 stable or progressive disease. The actuarial local progression-free survival was 66.0% at 1 year and 42.2% at 2 years following initiation of radiotherapy. CONCLUSIONS: These results show that celecoxib can be safely administered concurrently with thoracic radiotherapy when given up to the highest Food and Drug Administration-approved dose of 800 mg/d, which we used. A maximal tolerated dose was not reached in this study. The treatment resulted in actuarial local progression-free survival of 66.0% at 1 year and 42.2% at 2 years, an encouraging outcome that warrants further assessment in a phase II/III trial.  相似文献   
433.
PURPOSE: A phase I trial of BMS-214662, a selective farnesyltransferase inhibitor with significant preclinical antitumor activity in which drug was given as a weekly 1-hour infusion for four of six weeks, was conducted to evaluate the tolerability, pharmacokinetics, and pharmacodynamic effect on farnesyltransferase activity in peripheral blood mononuclear cells. EXPERIMENTAL DESIGN: BMS-214662 was given to 27 patients with solid tumors at 10 escalating dose levels (28-220 mg/m(2)) allowing intrapatient dose escalation; pharmacokinetics and pharmacodynamics were done at the first seven dose levels. RESULTS: Grade 4 neutropenia (four patients) was the most common dose-limiting toxicity followed by aminotransferase elevation (grade 3 alanine aminotransferase and grade 4 aspartate aminotransferase) and grade 3 dehydration. Most frequent toxicities were neutropenia in 11 (14%), anemia in 15 (19%), fatigue in 9 (12%), and nausea and diarrhea in 6 (8%) of courses, respectively. One minor response lasting 18 weeks in a patient with non-small cell lung cancer, serum calcitonin level reduction accompanied by disease stabilization in two of four patients with medullary thyroid carcinoma, and stable disease in 16 of 25 evaluable patients was seen. No correlation was observed between dose and C(max), total body clearance (mean, 26.15 +/- 10.88 L per hour per m(2)), volume of distribution at steady state (mean, 39.51 +/- 17.91 L/m(2)), or half-life (mean, 2.63 +/- 1.81 hours); a moderate correlation existed between dose given and systemic drug exposure (AUC). Substantial inhibition of peripheral blood mononuclear cell farnesyltransferase activity but near complete recovery by 24 hours was seen. CONCLUSION: BMS-214667 was well tolerated as a weekly 1-hour i.v. infusion for four of six weeks with evidence of pharmacodynamic effect. The study was terminated before maximum tolerated dose was reached. Alternative schedules of drug administration might result in improved pharmacodynamic profile.  相似文献   
434.
PURPOSE: To establish the maximum tolerated dose of lonafarnib, a novel farnesyltransferase inhibitor, in combination with paclitaxel in patients with solid tumors and to characterize the safety, tolerability, dose-limiting toxicity, and pharmacokinetics of this combination regimen. EXPERIMENTAL DESIGN: In a Phase I trial, lonafarnib was administered p.o., twice daily (b.i.d.) on continuously scheduled doses of 100 mg, 125 mg, and 150 mg in combination with i.v. paclitaxel at doses of 135 mg/m(2) or 175 mg/m(2) administered over 3 h on day 8 of every 21-day cycle. Plasma paclitaxel and lonafarnib concentrations were collected at selected time points from each patient. RESULTS: Twenty-four patients were enrolled; 21 patients were evaluable. The principal grade 3/4 toxicity was diarrhea (5 of 21 patients), which was most likely due to lonafarnib. dose-limiting toxicities included grade 3 hyperbilirubinemia at dose level 3 (100 mg b.i.d. lonafarnib and 175 mg/m(2) paclitaxel); grade 4 diarrhea and grade 3 peripheral neuropathy at dose level 3A (125 mg b.i.d. lonafarnib and 175 mg/m(2) paclitaxel); and grade 4 neutropenia with fever and grade 4 diarrhea at level 4 (150 mg b.i.d. lonafarnib and 175 mg/m(2) paclitaxel). The maximum tolerated dose established by the continual reassessment method was lonafarnib 100 mg b.i.d. and paclitaxel 175 mg/m(2). Paclitaxel appeared to have no effect on the pharmacokinetics of lonafarnib. The median duration of therapy was eight cycles, including seven cycles with paclitaxel. Six of 15 previously treated patients had a durable partial response, including 3 patients who had previous taxane therapy. Notably, two of five patients with taxane-resistant metastatic non-small cell lung cancer had partial responses. CONCLUSIONS: When combined with paclitaxel, the recommended dose of lonafarnib for Phase II trials is 100 mg p.o. twice daily with 175 mg/m(2) of paclitaxel i.v. every 3 weeks. Additional studies of lonafarnib in combination regimens appear warranted, particularly in patients with non-small cell lung cancer.  相似文献   
435.
PURPOSE: To compare four cycles of therapy versus continuous therapy to determine the optimal duration of chemotherapy in advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Stage IIIB/IV NSCLC patients were randomized to arm A (four cycles of carboplatin at an area under the curve of 6 and paclitaxel 200 mg/m(2) every 21 days) or arm B (continuous treatment with carboplatin/paclitaxel until progression). At progression, all patients on both arms were to receive second-line weekly paclitaxel at 80 mg/m(2)/wk. The primary end points were survival and quality of life (QOL). RESULTS: Two hundred thirty patients were randomized. Fifty-seven percent of arm A patients completed four courses of therapy. In the 116 arm B patients, the median number of cycles delivered was four (range, zero to 19 cycles). Forty-two percent received five or more cycles; 18% received eight or more cycles. Overall response rates were 22% and 24% for arms A and B, respectively (P =.80). Median survival time and 1-year survival rates were 6.6 months and 28% for arm A and 8.5 months and 34% for arm B, respectively (log-rank P =.63). Rates of hematologic and nonhematologic toxicity were similar between the two arms, except for neuropathy. The rate of grade 2 to 4 neuropathy increased from 19.9% (95% confidence interval [CI], 13.6% to 26.2%) at cycle 4 to 43% (95% CI, 28.6% to 57.4%) at cycle 8. There were no differences in QOL. Only 45% of patients received second-line therapy (42% in arm A v 47% in arm B, P =.42). CONCLUSION: This study shows no overall benefit in survival, response rates, or QOL to continuing treatment with carboplatin/paclitaxel beyond four cycles in advanced NSCLC.  相似文献   
436.
After obesity surgery, the primary measurement of success is the amount of weight lost. There has, however, been little assessment of how patients cope with the dietary constraints imposed by gastroplasty. Similarly, dietary patterns adopted to cope with these constraints have not been studied fully. These factors are of great importance in terms of nutritional adequacy, patient acceptability and long-term success. A study involving 32 patients was conducted to ascertain whether practical nutritional intervention and extensive follow-up would improve the overall outcome of the gastroplasty operation with respect to the type of foods tolerated and the incidence of regurgitation or vomiting experienced. To quantitate success in terms of frequency of regurgitation and variety of food intake a vomiting/eating (V/E) score was devised. The results showed that the group of patients with more intensive practical education and counselling had a more varied intake of food and coped better with a wider variety of solid foods in the long term. Despite a more solid diet they did not regurgitate food as frequently as patients with less education, and over half the study group of patients reported no regurgitation at all. From this study, it is proposed that patients can be assessed and categorized postoperatively using a V/E scale. This scale numerically scores success with diet after gastroplasty, which, when recorded in conjunction with subsequent weight loss, can give a better quantification of success after obesity surgery.  相似文献   
437.

Background  

Several methodological approaches have been used to estimate distance in health service research. In this study, focusing on cardiac catheterization services, Euclidean, Manhattan, and the less widely known Minkowski distance metrics are used to estimate distances from patient residence to hospital. Distance metrics typically produce less accurate estimates than actual measurements, but each metric provides a single model of travel over a given network. Therefore, distance metrics, unlike actual measurements, can be directly used in spatial analytical modeling. Euclidean distance is most often used, but unlikely the most appropriate metric. Minkowski distance is a more promising method. Distances estimated with each metric are contrasted with road distance and travel time measurements, and an optimized Minkowski distance is implemented in spatial analytical modeling.  相似文献   
438.
Chemotherapy for skull base cancers.   总被引:3,自引:0,他引:3  
This article focuses on treatment options for select skull base problems that have decreased post-treatment morbidity and, in many cases, improved survival. The select skull base cancers covered include nasopharyngeal carcinoma, squamous cell carcinoma of the paranasal sinuses, sinonasal undifferentiated carcinoma, neuroendocrine carcinoma, esthesioneuroblastoma, and salivary gland carcinoma.  相似文献   
439.
PURPOSE: To determine, pretreatment, how head and neck cancer (HNC) patients prioritize potential treatment effects in relationship to each other and to survival and to ascertain whether patients' preferences are related to demographic or disease characteristics, performance status, or quality of life (QOL). PATIENTS AND METHODS: One hundred thirty-one patients were assessed pretreatment using standardized measures of QOL (Functional Assessment of Cancer Therapy-Head and Neck) and performance (Performance Status Scale for Head and Neck Cancer). Patients were also asked to rank a series of 12 potential HNC treatment effects. RESULTS: Being cured was ranked top priority by 75% of patients; another 18% ranked it second or third. Living as long as possible and having no pain were placed in the top three by 56% and 35% of patients, respectively. Items that were ranked in the top three by 10% to 24% of patients included those related to energy, swallowing, voice, and appearance. Items related to chewing, being understood, tasting, and dry mouth were placed in the top three by less than 10% of patients. Excluding the top three rankings, there was considerable variability in ratings. Rankings were generally unrelated to patient or disease characteristics, with the exception that cure and living were of slightly lower priority and pain of higher priority to older patients compared with younger patients. CONCLUSION: The data suggest that, at least pretreatment, survival is of primary importance to patients, supporting the development of aggressive treatment strategies. In addition, results highlight individual variability and warn against making assumptions about patients' attitudes vis-à-vis potential outcomes. Whether patients' priorities will change as they experience late effects is currently under investigation.  相似文献   
440.
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