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   14477篇
  免费   1209篇
  国内免费   30篇
耳鼻咽喉   170篇
儿科学   496篇
妇产科学   295篇
基础医学   2300篇
口腔科学   356篇
临床医学   1454篇
内科学   3070篇
皮肤病学   246篇
神经病学   1075篇
特种医学   513篇
外国民族医学   1篇
外科学   1995篇
综合类   133篇
一般理论   8篇
预防医学   1139篇
眼科学   333篇
药学   1157篇
  1篇
中国医学   14篇
肿瘤学   960篇
  2022年   97篇
  2021年   224篇
  2020年   198篇
  2019年   251篇
  2018年   274篇
  2017年   266篇
  2016年   309篇
  2015年   280篇
  2014年   401篇
  2013年   538篇
  2012年   701篇
  2011年   662篇
  2010年   396篇
  2009年   374篇
  2008年   572篇
  2007年   610篇
  2006年   558篇
  2005年   539篇
  2004年   609篇
  2003年   496篇
  2002年   483篇
  2001年   421篇
  2000年   466篇
  1999年   407篇
  1998年   191篇
  1997年   158篇
  1996年   171篇
  1995年   149篇
  1994年   148篇
  1993年   145篇
  1992年   305篇
  1991年   337篇
  1990年   330篇
  1989年   347篇
  1988年   262篇
  1987年   279篇
  1986年   237篇
  1985年   288篇
  1984年   191篇
  1983年   164篇
  1982年   126篇
  1981年   103篇
  1980年   91篇
  1979年   165篇
  1978年   124篇
  1977年   107篇
  1975年   97篇
  1974年   117篇
  1973年   105篇
  1972年   86篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
Extracorporeal membrane oxygenation (ECMO) may serve as extracorporeal lung assist (ECLA) in patients with acute respiratory failure (ARF) or as extracorporeal heart assist (ECHA) in patients with low output syndrome (LOS) after open heart surgery. From 1988 to 1992 seven patients underwent ECMO in our hospital; four suffered from ARF and three from LOS. Various bypass techniques were employed. Two ARF patients, aged 58 and 18 years, had veno-venous bypass; in the latter, ECMO was reinstituted as a veno-arterial bypass one week after weaning. In a three-year-old boy, the ECMO outflow tubing was primarily connected to the pulmonary artery, and shortly afterwards relocated to the common carotid artery. In a 31-year-old man with ARF, and three LOS patients, a 56-year-old woman, and two men aged 68 and 70 years, ECMO was veno-arterial with direct access to the ascending aorta. A heparin-coated system was used, and all but one patient, who was treated with warfarin, received a daily low dose of heparin, which was withdrawn after from one to nine days.
Six patients were weaned off ECMO after 4.5 to 21 days. Three ARF patients recovered completely; the child died. In one LOS patient, ECMO was withdrawn due to a poor general condition. Two others were weaned off ECMO and the intra-aortic balloon pump, and the inotropic support was significantly reduced, but both died of multiple system organ failure. Although no firm conclusions can be drawn from these few case reports, the heparin-coated system used as ECLA appears promising, whereas ECHA seems to imply a poor prognosis in patients who are not candidates for cardiac transplantation.  相似文献   
92.
BACKGROUND: Pediatric asthma is the No. 1 chronic disease in childhood and is responsible for significant morbidity and mortality. In Nebraska, the number of asthma-related deaths is greater than the national average, and in 1998, 2 students died of acute asthma attacks while attending school in the Omaha public schools (OPSs). In response, we designed and implemented a program to respond to this problem. OBJECTIVE: To implement and study a school-based program for the treatment of life-threatening asthma and anaphylaxis in the OPSs. METHODS: The Emergency Response to Life-Threatening Asthma or Systemic Allergic Reactions (Anaphylaxis) Protocol was designed and evaluated in 78 OPSs from 1998 to 2003. Nurses and school staff were trained in the protocol, which required the use of nebulized albuterol and/or intramuscular epinephrine in conjunction with an emergency response procedure. Outcomes were measured by improvement in acute care in schools and survival of students. Results: In the 5 years of evaluation, 98 students were treated successfully. One student died. Of those treated with the protocol, equal numbers had at school both asthma action plans (AAPs) and metered-dose inhalers (MDIs), MDIs only, or neither AAPs nor MDIs. As a result of the program, there has been an increased awareness from parents, teachers, and physicians about the necessity of an emergency response program. In 2002, an outcome of the OPS program resulted in the formation of Attack on Asthma Nebraska to ensure that Nebraska schools have the education, training, and medications to respond to anyone experiencing a life-threatening asthma or anaphylaxis attack at school. The following year, a revised protocol was approved by the Nebraska State Board of Education for use in all Nebraska schools. CONCLUSIONS: Emergency response protocols provide protection for children while in school. This program should serve as a national model for other school-based programs for children and adolescents with asthma and anaphylaxis.  相似文献   
93.
94.
Follow-up information was obtained on 185 patients who consecutively underwent carotid endarterectomy eight to ten years previously. Doppler ultrasound examination was performed in 59 patients who were still alive and living within 100 miles of the hospital. Using lifetable analysis, the annual rate of focal strokes was estimated to be 2% and 1.5% on the operated and the contralateral, non-operated carotid artery, respectively. Doppler examination revealed 48% re-stenoses, including 14% occlusion and 15% greater than 50% stenosis. However, there was no association between the occurrence of restenosis and the development of symptoms, perhaps with the exception of internal carotid artery occlusion, which is not an accepted indication for carotid endarterectomy. Together with recent data from the literature, these observations challenge the indication for reoperative carotid surgery.  相似文献   
95.
Cryptic osteoid osteoma of the cranium: case report   总被引:1,自引:0,他引:1  
Osteoid osteoma is an uncommon benign tumor of bone that rarely involves the cranium. If often causes local pain that is worse at night, characteristically relieved by aspirin, and does not correlate with the size of the lesion. The diagnosis depends on skull radiographs and computed tomography. This report describes a case in which radiographs showed nothing abnormal. The diagnosis and operative localization were accomplished with radionuclide bone scanning. Thus, the possibility of radiographically cryptic lesions must be considered in the evaluation of atypical head pain syndromes.  相似文献   
96.
Few studies have investigated the reproductive effects of exposure to chemical mixtures. The purpose of this study was to assess fertility in males exposed to mixed industrial and domestic wastes. A detailed reproductive history was obtained from the wives of 231 employees in order to evaluate fertility. Daily work records were used to define exposure status. To ascertain problems of infertility, the ratios of observed live births to expected live births (generated from U.S. birth probabilities) for exposed and nonexposed groups were calculated, and the ratios of these Standardized Fertility ratios (SRFs) were compared. Other analyses considered the couples' contraceptive history and preexposure versus postexposure experience. Though multiple statistical approaches were used to examine the data, the conclusion of this study was that exposure to chemical mixtures was not associated with a decrease in the couples' fertility.  相似文献   
97.
The enantiomers of alpha-amino-4-bromo-3-hydroxy-5-isoxazolepropionic acid (4-bromohomoibotenic acid, Br-HIBO, 1) a selective and potent agonist at one class of the central (S)-glutamic acid receptors, were prepared with an enantiomeric excess higher than 98.8% via stereoselective enzymic hydrolysis of (RS)-alpha-(acetylamino)-4-bromo-3-methoxy-5-isoxazolepropionic acid (4) using immobilized aminoacylase. The absolute configuration of the enantiomers of Br-HIBO was established by X-ray crystallographic analysis, which confirmed the expected preference of the enzyme for the S form of the substrate 4. (S)- and (RS)-Br-HIBO were potent neuroexcitants on cat spinal neurones in vivo, while (R)-Br-HIBO was a very weak excitant. Correspondingly, the S enantiomer of Br-HIBO (IC50 = 0.34 microM) was considerably more potent than the R form (IC50 = 32 microM) as an inhibitor of [3H]-(RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid ([ 3H]AMPA) binding to rat brain synaptic membranes in vitro. In contrast, (S)- and (R)-Br-HIBO were approximately equipotent (IC50 values of 0.22 and 0.15 microM, respectively) as inhibitors of [3H]-(S)-glutamic acid binding in the presence of CaCl2. The enantiomers of Br-HIBO showed no significant affinity for those binding sites on rat brain membranes which are labeled by [3H]kainic acid or [3H]-(R)-aspartic acid.  相似文献   
98.
99.
J E Hansen  J Iversen  A Lihme  T C B?g-Hansen 《Cancer》1987,60(7):1630-1635
The acute phase proteins, orosomucoid, ceruloplasmin, antitrypsin, and haptoglobin were measured in serum from 54 patients with lung cancer, 16 patients with benign lung inflammation, and 30 healthy individuals. A statistical correlation was found between tumor size and acute phase protein level, which, however, was ascribed to nonspecific inflammation in the tissues surrounding the tumor. The patients who subsequently could not be radically treated by surgery had higher concentrations of orosomucoid and ceruloplasmin than the radically treated patients. No difference in acute phase protein concentration was found between benign and malignant disease. The glycan-dependent microheterogeneity of orosomucoid and ceruloplasmin was analyzed by crossed affinoimmunoelectrophoresis with lectins, and the patterns of the patients with benign inflammation and malignant disease were different. The heterogeneity of ceruloplasmin was also analyzed by crossed immunoelectrophoresis without lectin. This analysis, combined with the total serum concentration of ceruloplasmin, made it possible to discriminate the 54 cases of malignancy from the 46 cases of nonmalignancy with a sensitivity of 78% and a specificity of 93%. It is suggested that the simple electrophoretic analyses of (micro-)heterogeneity is a valuable supplement to the acute phase profile in isolating high-risk patients and in monitoring radically treated cancer patients for relapse.  相似文献   
100.
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