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   900977篇
  免费   63372篇
  国内免费   2328篇
耳鼻咽喉   12515篇
儿科学   28704篇
妇产科学   26177篇
基础医学   126947篇
口腔科学   24701篇
临床医学   74996篇
内科学   183705篇
皮肤病学   19052篇
神经病学   71545篇
特种医学   36509篇
外国民族医学   336篇
外科学   142352篇
综合类   19059篇
一般理论   248篇
预防医学   64701篇
眼科学   20114篇
药学   63924篇
中国医学   1798篇
肿瘤学   49294篇
  2018年   9090篇
  2017年   7187篇
  2016年   7706篇
  2015年   8755篇
  2014年   12425篇
  2013年   19271篇
  2012年   25784篇
  2011年   27373篇
  2010年   16631篇
  2009年   15847篇
  2008年   26218篇
  2007年   27824篇
  2006年   27988篇
  2005年   27530篇
  2004年   26398篇
  2003年   25548篇
  2002年   25117篇
  2001年   41445篇
  2000年   42651篇
  1999年   36329篇
  1998年   9994篇
  1997年   9170篇
  1996年   9112篇
  1995年   8465篇
  1994年   8106篇
  1993年   7606篇
  1992年   28242篇
  1991年   27022篇
  1990年   26450篇
  1989年   25371篇
  1988年   23586篇
  1987年   23203篇
  1986年   22278篇
  1985年   21183篇
  1984年   15836篇
  1983年   13507篇
  1982年   8108篇
  1979年   14617篇
  1978年   10228篇
  1977年   8647篇
  1976年   8158篇
  1975年   8966篇
  1974年   10709篇
  1973年   10194篇
  1972年   9672篇
  1971年   8930篇
  1970年   8596篇
  1969年   8034篇
  1968年   7698篇
  1967年   7101篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
OBJECTIVE: Avoidance of potential iatrogenic nerve injury during insertion of Ilizarov fine wires into areas of high anatomic risk by using a modified nerve stimulation technique. INDICATIONS: Application of the Ilizarov ring fixator to areas of high anatomic hazard, in situations where anatomic topography may be distorted by previous surgery, trauma, or congenital anomalies. CONTRAINDICATIONS: Use of systemic muscle relaxants. Caution in patient with cardiac pacemaker. SURGICAL TECHNIQUE: Preliminary experiments showed that a standard nerve-stimulating device can deliver a negatively charged, monophasic square pulse of current through Ilizarov wires. During the application of an Ilizarov frame to potentially hazardous anatomic regions, providing no systemic muscle relaxants are used, a voltage field sufficient to cause nerves in close proximity to the Ilizarov wire to depolarize is produced. Identification of a distal muscle twitch provoked by the stimulation may indicate a potential for iatrogenic nerve injury. RESULTS: Results show that with the nerve stimulator set at 2.5 mA (pulsed at a frequency of 2 Hz), peripheral nerves are stimulated if they lie within 5 mm of the wires. Should a distal muscle twitch occur, wires should be repositioned so that equivalent stimulation produces no twitch. The technique was used during Ilizarov frame application in ten patients, with only a single occurrence of distal muscle twitches in a lower-leg frame. Following repositioning of the Ilizarov wire in this case, no further twitches were observed, indicating that no Ilizarov wire was inserted close to peripheral nerves. No neurologic impairment was present postoperatively.  相似文献   
992.
993.
994.
995.
Background: The Lichtenstein technique for inguinal hernia repair is easy to learn and associated with few complications. However, recent studies have suggested that this technique is inferior to some ‘sutureless’ repair systems in terms of perceived difficulty, operating time, surgeon satisfaction, etc. Methods: We employed a sutureless Lichtenstein technique in 80 consecutive patients with primary unilateral inguinal hernia, to assess patient and trainee surgeon outcomes. Human fibrin glue was used in place of conventional sutures. Results: The mean operating time was 36 min and all patients were discharged 5–6 h after the operation. On a 100-point visual analogue scale, the surgeons rated the difficulty of the operation as low (mean score, 31), and perceived satisfaction as high (mean score, 84). No complications were observed at 12-month follow-up. Conclusion: This study confirms the efficacy of mesh fixation with human fibrin glue, and supports the viability of a sutureless Lichtenstein procedure.  相似文献   
996.
The role played by dendritic cell (DC) subsets in the immune response to alloantigens is not well defined. In vitro experiments have extensively shown that freshly isolated myeloid (M)DCs induce a strong T lymphocyte proliferation whereas plasmacytoid (P)DCs do not, unless activated by CD40 ligation. The aim of these studies was to explore whether the interplay among PDCs, MDCs and T cells modulates alloresponse. Freshly isolated MDCs and PDCs were merged in different proportions and used as antigen presenting cells (APCs) in mixed lymphocyte cultures (MLC). As described, isolated PDCs only induced a mild alloresponse, while MDCs were potent inducers of alloproliferation. Unexpectedly, when PDCs were merged with even low numbers of MDCs (down to 100 cells) and used as APCs, a potent Th1 cell proliferation was detected. Survival and maturation of PDCs was increased in these MLC conditions, which could partially explain the magnitude of the T-cell response. Interestingly, the proportion of IFNgamma-producing cells generated in such cultures was higher compared to MDC-stimulated cultures. These data suggest that the interaction between both DC subsets is determinant to generate a potent Th1 response, at least in an allogeneic situation, and may be relevant to the outcome of allogeneic stem cell transplantation.  相似文献   
997.
We describe a novel procedure for an anatomically-based face lift to correct vertical vectors in the ageing face. It has the advantage of surgical simplicity, minimal tissue removal and minimal risk. It provides an effective readjustment of cheek volume and correction of periorbital hollowness. Natural facial expression is preserved largely because there is no change in the position of the lateral canthus. The cheek is mobilised subperiosteally through a blepharoplasty incision. A second dissection is made via a short temporal incision, to join the infraorbital dissection. A Hagedorn needle is then inserted through a point inferior to the lateral canthus and in line horizontally with the nasal ala. It is passed to the orbital incision, charged with a loop of suture material, and pulled down again to the cheek incision, from where it is pushed back to the orbit to suspend the cheek. The upper border of orbicularis oculi is fixed firmly to the temporalis aponeurosis at the level of the temporal incision. We now frequently use an Endotine Midface device for fixation. Of the first 150 patients, results were excellent or good in 145. This represents a revival of the subperiosteal mask lift, and abandons the use of endoscopic techniques. In spite of its simplicity, the operation involves subperiosteal dissection as well as delicate eyelid surgery that necessitate plastic surgical skill.  相似文献   
998.
Zusammenfassung GRUNDLAGEN: Kenntnisse der Anatomie des Truncus sympathicus und des autonomen Nervensystems sind von großer Bedeutung in der Sympathikuschirurgie. Allerdings existiert eine Vielzahl an unterschiedlichen sympathischen Nervenverbindungen zur oberen Extremität, wobei der Großteil im ersten Zwischenrippenraum zu liegen kommt. Aus unterschiedlichsten Gründen führt die chirurgische Sympathektomie im Bereich der oberen thorakalen Ganglien zu einer Unterbrechung der sympathischen Innervation der oberen Extremität. Entscheidend ist, diese variablen Verbindungen zu durchtrennen, um optimale chirurgische Ergebnisse zu erzielen. METHODIK: Diese Arbeit basiert auf einer Durchsicht der Literatur der letzten 80 Jahre über die Anatomie des kranialen thorakalen Truncus sympathicus und seiner Verbindungen, die in der Sympathikuschirurgie von besonderer Bedeutung sind. Die Evaluation basiert auf einer Literaturrecherche in der Medline, ergänzt um Wissen aus Anatomiebüchern; es wird zudem eine Übersicht über die historische Entdeckung des sympathischen Systems gegeben. ERGEBNISSE: Zwei wichtige Ergebnisse liegen vor. 1. Intrathorakale Nervenverbindungen zwischen zweitem und erstem intrathorakalen Nerv dürften sympathische Fasern der oberen Extremität zuführen. Diese Verbindungen kommen bei mehr als 50 % der Menschen vor und dürften für Misserfolge und/oder Rezidive nach Sympathektomie verantwortlich sein. 2. Aktuelle chirurgische Studien weisen darauf hin, dass das Hauptganglion für die sympathische Innervation der oberen Extremität im Segment T4 liegen könnte. Dies steht jedoch im Gegensatz zur bisher anerkannten Ansicht, dass das Hauptganglion der sympathischen Innervation für die obere Extremität das T2-Ganglion sei. Bislang können diese klinischen Erkenntnisse nicht durch anatomisches Wissen erklärt werden. SCHLUSSFOLGERUNGEN: Profunde anatomische Kenntnisse sind eine unabdingbare Voraussetzung, um in der Sympathikuschirurgie optimale Ergebnisse zu erzielen.  相似文献   
999.
1000.
Renal cell carcinomas may extend into the vena cava and the tumor thrombus occasionally involves the right atrium. The operative approach depends upon precise preoperative and intraoperative staging and thrombus localization. We report a case of renal cell carcinoma with complete inferior vena caval and hepatic vein occlusion with tumor extension into the right atrium. Preoperatively, transesophageal echocardiography provided superior images of the tumor and its extension, and intraoperatively allowed continuous monitoring of cardiac function and the removal of tumor from the atrium and inferior vena cava. Its use obviated the need for more costly and invasive preoperative and intraoperative procedures.  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