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   4815篇
  免费   573篇
  国内免费   14篇
耳鼻咽喉   33篇
儿科学   96篇
妇产科学   88篇
基础医学   554篇
口腔科学   51篇
临床医学   541篇
内科学   1442篇
皮肤病学   139篇
神经病学   569篇
特种医学   216篇
外科学   610篇
综合类   72篇
一般理论   4篇
预防医学   347篇
眼科学   43篇
药学   288篇
中国医学   3篇
肿瘤学   306篇
  2021年   52篇
  2020年   31篇
  2019年   77篇
  2018年   87篇
  2017年   63篇
  2016年   71篇
  2015年   88篇
  2014年   117篇
  2013年   142篇
  2012年   234篇
  2011年   224篇
  2010年   134篇
  2009年   137篇
  2008年   226篇
  2007年   272篇
  2006年   262篇
  2005年   265篇
  2004年   198篇
  2003年   218篇
  2002年   202篇
  2001年   190篇
  2000年   187篇
  1999年   140篇
  1998年   49篇
  1997年   56篇
  1996年   66篇
  1995年   35篇
  1994年   50篇
  1993年   33篇
  1992年   98篇
  1991年   113篇
  1990年   114篇
  1989年   80篇
  1988年   78篇
  1987年   99篇
  1986年   69篇
  1985年   83篇
  1984年   55篇
  1983年   46篇
  1982年   43篇
  1981年   29篇
  1979年   41篇
  1977年   36篇
  1975年   34篇
  1974年   41篇
  1973年   30篇
  1972年   38篇
  1971年   39篇
  1970年   32篇
  1969年   43篇
排序方式: 共有5402条查询结果,搜索用时 15 毫秒
91.
92.
An open study was carried out in 17 acutely ill, newly admitted, floridly psychotic schizophrenic patients to a city hospital in New York. Penfluridol was given on a daily basis up to doses of 120 mg and patients were rated objectively by means of different psychometric evaluations; vital signs were monitored daily as were side effects.The drug was found to be a rapid acting, well-tolerated, and highly effective antipsychotic agent within the population of patients explored and within the dose range used. It was particularly effective in acutely agitated floridly paranoid schizophrenics; a statistically significant impact was achieved by 7 days and usually within 72 h after initiating treatment. The drug appears unique in that (1) its effects are realized without the untoward and usually trouble-some effects of nonspecific sedation attendant upon the use of many other neuroleptic medications, and (2) even within the relatively high doses used it produces no hypotensive effects. It is concluded that this appears to be a unique antipsychotic agent and a potentially important addition to the treatment armamentarium of both acute and chronic schizophrenic individuals.Dr. Klein was a research fellow who has since returned to the University of Munich, West Germany. Dr. Selzer was also a research fellow who is now in private practice  相似文献   
93.
"On the job" motor vehicle deaths number more than 4,000 annually in the U.S. and comprise nearly one-third of all work-related deaths. Yet the Department of Labor has set no standards relating to on-the-road safety of the millions of workers whose jobs entail large amounts of driving, and Department of Transportation standards affecting occupational safety cover only drivers in interstate commerce. Drivers of some commercial vehicles, such as heavy trucks, are at special risk of injury because trucks have usually been exempted for many years from federal motor vehicle safety standards--such as standards for brakes and seatbelts--designed to prevent crashes or protect occupants in crashes. Observations based on a series of 150 fatal crashes involving tractor trailers illustrate the need for better protection of this large population of high-risk workers. Clarification of responsibility within the various federal agencies and application of available knowledge and technology are essential.  相似文献   
94.
Post-transplantation lymphoproliferative disease (PTLD) is a complication of solid organ transplantation that is typically of B-cell origin and associated with Epstein-Barr virus (EBV). In patients receiving orthotopic liver transplantation (OLT) and treated with cyclosporin A. PTLD typically presents between 6 and 17 months post-transplantation as a systemic illness with involvement of the hepatic graft in a minority of cases. A small number of cases of biopsy-proven PTLD arising in the hepatic graft and limited to the liver and periportal structures have been previously reported. This report describes three additional cases of liver-localized PTLD and reviews similar cases in the literature. The donor/host origin of PTLD may have prognostic significance because the two cases in this report that are of donor origin had different clinical and pathologic features compared with the case of host origin. A rapid PCR-based technique for determining the origin of PTLD is described.  相似文献   
95.
PURPOSE: To assess the efficacy and toxicity of chemotherapy alone in patients older than 60 years with primary CNS lymphoma. PATIENTS AND METHODS: Fifty patients with a median age of 72 years and a median Karnofsky performance score (KPS) of 50 were eligible for this multicenter phase II study. The protocol consisted of high-dose methotrexate (MTX), lomustine, procarbazine, methylprednisolone, and intrathecal chemotherapy with MTX and cytarabine. The patients received one induction cycle; if objective response was achieved, five additional maintenance cycles were administered every 6 weeks. The median follow-up of patients was 3 years. RESULTS: Twenty four patients (48%) achieved an objective response (compete response [CR], 42%; partial response, 6%), with a median duration of CR of 27 months (range, 3 to 47+ months). Overall median survival time was 14.3 months, and 1-year progression-free survival was 40% (95% confidence interval [CI], 26% to 53%). Myelosuppression was the most frequent side effect, with grade 3 to 4 neutropenia in 19% of patients. One patient died during chemotherapy, as a result of pulmonary embolism. Most patients improved or preserved their cognitive functions (47% and 45% of the patients, respectively) and KPS (36% and 52% of the patients, respectively) until relapse, whereas cognitive and KPS decline attributed to delayed treatment neurotoxicity occurred in 8% and 12% patients, respectively. CONCLUSION: In the elderly, this chemotherapy regimen compares favorably with radiotherapy (RT) alone and reduces considerably the risk of delayed neurotoxicity associated with combined chemoradiotherapy. Chemotherapy alone is an appropriate strategy in older patients to delay or avoid RT.  相似文献   
96.
97.
OBJECTIVE. The purpose of this article is to present the imaging findings and correlative pathologic findings of infarcted regenerative nodules in the cirrhotic liver. CONCLUSION. Infarcted regenerative nodules exhibit a spectrum of imaging appearances in the cirrhotic liver and can resemble hypovascular hepatocellular carcinoma or other neoplasms on CT and MR imaging. Although uncommon, this abnormality must be included in the differential diagnosis of focal liver lesions in patients with cirrhosis, particularly in patients with a history of substantial gastrointestinal bleeding. Serial imaging may help differentiate these lesions from malignant tumors.  相似文献   
98.
Iliac vein compression syndrome: a new method of treatment   总被引:26,自引:0,他引:26  
Iliac vein compression syndrome (May-Thurner syndrome) is caused by compression of the left iliac vein against the pelvic rim by the right iliac artery. Serious vascular sequelae to the leg can result if this is not recognized and corrected in a timely fashion. The condition, often underdiagnosed, is thought to be present in approximately 20 per cent of the adult population. Previously, a major vascular operation with a significant hospital stay was required to correct this compression. As a nonsurgical option, we elected balloon dilation of the stenosed iliac vein, with insertion of a venous stent to maintain the restored lumen. Two patients who had this procedure have been followed for 12 months; venograms show continued patency of the iliac vein with no pressure gradient present. This procedure is safe and cost effective, and it requires a minimal hospital stay.  相似文献   
99.
Pulmonary hypertension with elevated pulmonary vascular resistance is a common cardiovascular complication associated with increased morbidity and mortality in preterm infants with chronic lung disease. Injury to the developing pulmonary circulation results in structural and functional abnormalities of the pulmonary vasculature. Animal studies have demonstrated that disruption of angiogenesis may contribute to the failure of normal alveolarisation in chronic lung disease. Levels of vascular endothelial growth factor in bronchoalveolar lavage fluid are lower in infants with chronic lung disease compared to preterm controls. Supplemental oxygen is commonly used to prevent and treat pulmonary hypertension, although optimal arterial oxygen saturation levels remain uncertain. Other vasodilators such as inhaled nitric oxide appear promising, but as yet have not been evaluated in the form of randomised controlled trials. Further studies are required to investigate the long-term effectiveness of pulmonary vasodilator therapy.  相似文献   
100.
Treatment of childhood-onset schizophrenia with olanzapine   总被引:4,自引:0,他引:4  
This paper reports on a clinical observation of 15 hospitalized youths ages 6-13 years diagnosed with childhood-onset schizophrenia and acutely treated with olanzapine. Initial sedation was the most common side effect observed. Youngsters who had not had a previous trial on any psychotropic did better than those that had failed a previous medication trial. Age was inversely correlated with positive response to olanzapine. Patients who experienced initial sedation did best once the initial sedation wore off. The majority of patients in the study improved on olanzapine.  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