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   13680篇
  免费   903篇
  国内免费   37篇
耳鼻咽喉   139篇
儿科学   512篇
妇产科学   371篇
基础医学   2030篇
口腔科学   201篇
临床医学   1621篇
内科学   2523篇
皮肤病学   323篇
神经病学   1699篇
特种医学   315篇
外科学   1363篇
综合类   67篇
一般理论   13篇
预防医学   1094篇
眼科学   234篇
药学   863篇
中国医学   17篇
肿瘤学   1235篇
  2023年   101篇
  2022年   182篇
  2021年   304篇
  2020年   251篇
  2019年   327篇
  2018年   367篇
  2017年   311篇
  2016年   374篇
  2015年   409篇
  2014年   510篇
  2013年   715篇
  2012年   1064篇
  2011年   1028篇
  2010年   639篇
  2009年   558篇
  2008年   871篇
  2007年   900篇
  2006年   890篇
  2005年   844篇
  2004年   770篇
  2003年   710篇
  2002年   682篇
  2001年   89篇
  2000年   54篇
  1999年   120篇
  1998年   166篇
  1997年   135篇
  1996年   103篇
  1995年   106篇
  1994年   66篇
  1993年   76篇
  1992年   51篇
  1991年   55篇
  1990年   48篇
  1989年   29篇
  1988年   36篇
  1987年   24篇
  1986年   28篇
  1985年   31篇
  1984年   32篇
  1983年   36篇
  1982年   42篇
  1981年   23篇
  1980年   34篇
  1979年   31篇
  1978年   19篇
  1977年   20篇
  1976年   28篇
  1975年   17篇
  1974年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Effect of positioning on oxygenation in single-lung transplant recipients.   总被引:1,自引:0,他引:1  
BACKGROUND: Many benefits and adverse effects of positioning are related to changes in ventilation and perfusion. A number of unique factors related to the allograft make the effects of positioning difficult to determine in single-lung transplant recipients. OBJECTIVES: To determine the effect of 3 body positions (supine, lateral with allograft lung down, and lateral with native lung down) on oxygenation and blood flow in single-lung transplant recipients in the 24 hours immediately after surgery. METHODS: A quasi-experimental repeated-measures design with stratified assignment to 1 of 3 different sequencing patterns for turning group was used to study 15 transplant recipients, 9 with emphysema and 6 with fibrosis. Oxygenation, ventilation, and blood flow measures (heart rate, blood pressure) were assessed after each turn. The effect of ischemic reperfusion injury was also explored. RESULTS: The oxygenation, ventilation, and bloodflow variables did not differ significantly across group, diagnosis, or time. Oxygenation variables measured when the allograft lung was dependent did not differ significantly from such measurements obtained when the native lung was dependent. CONCLUSIONS: No single position maximizes oxygenation in the immediate postoperative period in single-lung transplant recipients. Although a single standard protocol for positioning cannot be supported, the study does support the idea that transplant recipients can be safely turned in the immediate postoperative period without compromising oxygenation or hemodynamic status.  相似文献   
12.
Cholesteryl ester transfer protein (CETP) greatly affects the metabolism of all lipoprotein classes including low-density lipoprotein (LDL) and high-density lipoprotein (HDL), both known to constitute powerful risk factors for coronary artery disease (CAD). We now report the successful first cloning and characterization of single-chain antibody fragments specific for CETP. A recombinant phage display library was generated using spleen mRNA isolated from BALB/c mice that had been immunized with highly purified CETP. Screening of the library yielded two single-chain antibody fragments with high affinity for CETP, termed 1CL8 and 1CL10, displaying respective KD values of 4.36 x 10(-9) M and 4.64 x 10(-9) M as determined by affinity sensor technology. Amino acid sequence comparison indicated the complementarity-determining regions of the respective heavy chains to be responsible for CETP high affinity binding. Fragment 1CL8 was successfully employed in clinical chemical quantification systems that uncovered an association in humans between plasma CETP concentration and total body fat mass (r=0.50, p<0.002). Because of the demonstrated superb CETP capturing capacity, combined with high binding affinity to CETP, ready access and unlimited supply, 1CL8 and 1CL10 are expected to prove powerful tools for studies on the role of CETP in atherogenesis.  相似文献   
13.
Tension pneumomediastinum after severe vomiting in a 21-year-old female.   总被引:1,自引:0,他引:1  
A 21-year-old female with chronic membranoproliferative nephritis was admitted for suspected esophageal disruption and asthma after severe, prolonged vomiting. At the time of admission she presented with dyspnea, tachypnea, arterial hypotension and tachycardia. Physical examination showed discrete signs of ectopic air at the neck and distended cervical veins. CT-scan of the chest showed severe mediastinal emphysema with compression of the right atrium. After cervical mediastinotomy the cardiorespiratory parameters normalized immediately. Esophagoscopy showed multiple longitudinal mucosal tears between 25 and 45 cm; fluoroscopically, there was no leakage of contrast medium. Following conservative treatment the patient recovered completely and was discharged on day 8.  相似文献   
14.
15.
Sir, With great interest we read the editorial review of Jean etal. [1] on the relationship between hyperphosphataemia and mortalityin end-stage renal disease patients. The authors summarize resultsfrom the large USRDS and DOPPS studies in which associationsof hyperphosphataemia and increased mortality risks were  相似文献   
16.
Zusammenfassung. Ziel: Die psychische Belastung bei Patienten mit akutem Herzinfarkt innerhalb der ersten 48 h auf der Intensivstation des Städtischen Krankenhauses Kiel wird mit Hilfe der Symptom-Checkliste (SCL-90-R) gemessen. Patienten und Methodik: 134 hauptsächlich wegen eines akuten Herzinfarkts aufgenommene Patienten wurden zwischen August 1996 und Juli 1999 randomisiert ausgewählt. Sie füllten einen der Intensivstation angepassten Fragebogen aus, der u. a. neben Fragen zu sozioökonomischen Daten die standardisierten SCL-90-R enthält. Ergebnisse: Erhöhte Mittelwerte zeigten sich vor allem für die Skalen Somatisierung, Ängstlichkeit, Depressivität und GSI (Global Severity Index) bei solchen Patienten, die wenig soziale Unterstützung bekamen und über ein niedriges Einkommen verfügten. Schlussfolgerung: Da für Patienten mit schlechtem sozialen Netzwerk, niedrigem sozialen Status, erhöhter Angst und Depressivität eine schlechtere Prognose hinsichtlich der Mortalität und Wiedereingliederung in den Beruf beschrieben wurde, ist es im prospektiven Verlauf dieser Studie notwendig, gerade diese Patienten hinsichtlich der Entwicklung ihrer Angst zu erfassen und zu behandeln. Abstract. Objective: 134 patients with acute myocardial infarction, who were treated in an intensive care unit (ICU) of a German hospital in Kiel between 1996 and 1999 were selected for the study to examine their psychologic symptoms. Patients and Methods: The patients were asked to fill in the self-report inventory, the Symptom Checklist-90-Revised (SCL-90-R) within the first 48 h after their arrival in the ICU. Results: Patients with a low social status were found to have elevated mean values of the following scales: somatization (0.93), depression (0.66), and anxiety (0.59). The Global Severity Index (GSI) as a global measure of psychologic distress was elevated as well (0.46). Conclusion: Since patients with a limited social network and low social status, increased anxiety and depressive scores have a poor prognosis as to their mortality and their professional reintegration, it it considered necessary for the prospective setting of this study to register particularly those patients in order to treat their anxiety.  相似文献   
17.
18.
Cutaneous manifestations of Lyme borreliosis   总被引:1,自引:0,他引:1  
Summary The dermatological symptoms of Lyme borreliosis present with a typical clinical pattern and characteristic time of appearance. In contrast to other manifestations of Lyme borreliosis they are easily recognizable in most of the cases. In the first stage, erythema migrans arises at the tick bite site. With this symptom the diagnosis of Lyme borreliosis can be established. During all manifestations of Lyme borreliosis the history of erythema migrans is an important parameter to verify the diagnosis. In the early stage of disease a lymphocytic proliferation can appear at the tick bite site, at the ear lobe, or at the mamilla. Borrelia lymphocytoma can be diagnosed when antibodies againstBorrelia burgdorferi are positive. Years after infection, acrodermatitis chronica atrophicans arises at distal body sites causing livid swelling and gradually skin atrophy. Skin lesions can be accompanied by neuropathies, mostly of the lower legs, which in contrast to the skin lesions, do not respond well to antibiotic therapy. There is evidence that some cases of Shulman syndrome, morphea and lichen sclerosus et atrophicus might be related to a borrelia infection as indicated by cultivation ofB. burgdorferi from skin biopsies of morphea and response to antibiotic treatment in some cases. The classical dermatological symptoms of Lyme borreliosis, erythema migrans, borrelia lymphocytoma and acrodermatitis chronica atrophicans respond to oral antibiotic treatment. In acrodermatitis chronica atrophicans parenteral antibiotic therapy is sometimes necessary.
Hautmanifestationen der Lyme-Borreliose
Zusammenfassung Dermatologische Manifestationen der Lyme-Borreliose zeichnen sich durch ihr charakteristisches Erscheinungsbild und durch den typischen Zeitpunkt ihres Auftretens aus und sind im Gegensatz zu anderen Symptomen meist gut zu diagnostizieren. Die Diagnose des Erythema chronicum migrans, das an der Zeckenstichstelle entsteht, erlaubt einerseits die exakte Diagnose einer Lyme-Borreliose und stellt in Spätstadien oft einen wichtigen anamnestischen Parameter zur Verifizierung einer durchgemachten Borrelieninfektion dar. Lymphozytäre Proliferationen können einerseits an der Zeckenstichstelle, andererseits auch an abstehenden Körperpartien beobachtet werden. Ein Borrelienlymphozytom kann dann diagnostiziert werden, wenn Antikörper gegenBorrelia burgdorferi nachweisbar sind. Die Acrodermatitis chronica atrophicans entsteht nach jahrelanger Latenz an abstehenden Körperpartien und führt zur Hautatrophie. Gelegentlich sind Begleitneuropathien möglich, welche im Gegensatz zu den Hautveränderungen auf die antibiotische Therapie nicht so gut ansprechen. Es gibt Berichte, wonach einige Fälle von Shulman Syndrom, Morphea und Lichen sclerosus et atrophicus auch durch eine Infektion mitB. burgdorferi verursacht werden. Die Isolierung vonB. burgdorferi aus Morphealäsionen dürfte dazu einen direkten Hinweis geben. Die klassischen dermatologischen Symptome Erythema chronicum migrans, Borrelienlymphozytom und Acrodermatitis chronica atrophicans sprechen auf orale antibiotische Therapie an. Bei letzterer Erkrankung muß manchmal auf eine parenterale antibiotische Therapie zurückgegriffen werden.
  相似文献   
19.
A dysmorphic child was found by cytogenetic analysis to have an extra small marker chromosome. The marker chromosome was shown to possess a chromosome 18 centromere by in situ hybridization, and probably represents an isochromosome 18p. Centromere specific probes should be of value in identifying extra small marker chromosomes, and thereby provide better understanding of the clinical significance of these.  相似文献   
20.
Examined the changing profiles of intelligence in males with fragile X syndrome as these individuals increased in chronological age. Using a psychometric instrument designed to measure styles of information processing, 21 males aged 4 to 27 years were examined cross-sectionally in sequential processing, simultaneous processing, and achievement. The age of the subject was associated with age-equivalent levels of both simultaneous processing and achievement, but fragile X males did not show higher levels of sequential processing with increasing chronological age. Compared to younger fragile X males, the older subjects were more delayed in sequential processing skills relative to their abilities in other areas. A smaller longitudinal study confirmed the presence of a plateau in sequential processing among those subjects tested two times after the age of 10 years. Implications are discussed for diagnosis, intervention, and the matching of subject groups in mental retardation research.This research was supported in part by the John Merck Fund, the Joseph P. Kennedy, Jr. Foundation, NIH grants RR00125 and HD03008, and NIMH grants MH18268 and MH30929. We thank Wendy Marans and Joel Bregman for their comments on an earlier draft of this paper.  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