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   13596篇
  免费   1030篇
  国内免费   281篇
耳鼻咽喉   127篇
儿科学   487篇
妇产科学   249篇
基础医学   388篇
口腔科学   19篇
临床医学   3095篇
内科学   4527篇
皮肤病学   37篇
神经病学   217篇
特种医学   633篇
外国民族医学   1篇
外科学   1904篇
综合类   1630篇
预防医学   652篇
眼科学   51篇
药学   581篇
  10篇
中国医学   85篇
肿瘤学   214篇
  2024年   15篇
  2023年   230篇
  2022年   209篇
  2021年   490篇
  2020年   515篇
  2019年   486篇
  2018年   448篇
  2017年   494篇
  2016年   500篇
  2015年   539篇
  2014年   1013篇
  2013年   961篇
  2012年   897篇
  2011年   864篇
  2010年   706篇
  2009年   661篇
  2008年   593篇
  2007年   589篇
  2006年   553篇
  2005年   476篇
  2004年   469篇
  2003年   374篇
  2002年   334篇
  2001年   288篇
  2000年   242篇
  1999年   239篇
  1998年   234篇
  1997年   185篇
  1996年   153篇
  1995年   117篇
  1994年   151篇
  1993年   133篇
  1992年   113篇
  1991年   84篇
  1990年   57篇
  1989年   86篇
  1988年   71篇
  1987年   45篇
  1986年   40篇
  1985年   52篇
  1984年   39篇
  1983年   22篇
  1982年   29篇
  1981年   30篇
  1980年   19篇
  1979年   16篇
  1978年   14篇
  1977年   11篇
  1976年   11篇
  1973年   4篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
91.
目的初步探讨应用球囊扩张椎体后凸成形术治疗骨质疏松性椎体压缩骨折的临床疗效。方法应用球囊扩张椎体后凸成形术治疗骨质疏松性椎体压缩骨折患者24例28个椎体,并随访4~11个月,平均8个月。结果所有患者手术均获成功,无脊髓神经损伤,病椎疼痛缓解,后凸畸形平均矫正20°,随访期间,疗效满意,无病椎高度丢失。结论应用经皮椎体成形术治疗骨质疏松性椎体压缩骨折能明显改善患者疼痛症状,恢复椎体高度,矫正后凸畸形,是一种安全的微创方法。  相似文献   
92.
Microorganisms detected in situ on the distal tip of central venous catheters (CVC) within 90 min of insertion were investigated using pulsed-field gel electrophoresis to analyse genomic fragments obtained with theSmaI restriction enzyme. Thirty patients received a triple lumen CVC, which was inserted directly through the skin using the Seldinger technique. In a further 30 patients a triple lumen CVC was inserted through a Swan sheath, thereby avoiding direct contact of the CVC with the skin. Staphylococci were isolated from the distal tips of the catheters in 6 patients (5 who had the CVC inserted directly through the skin and 1 who had the CVC inserted via a Swan sheath.) Twenty-three staphylococcal isolates were also isolated from the insertion equipment and the skin swabs surrounding the insertion site of these six patients. All the isolates were genotyped. In one of the patients the organisms isolated from the skin were identical to those on the CVC tip. In two further patients similar organisms were isolated from the insertion equipment and the patients' skin. These results, in addition to the reduced colonisation rates observed when catheters were introduced through a Swan sheath, support the hypothesis that microorganisms from the skin are impacted onto the CVC tip and the CVC insertion equipment at catheter insertion.  相似文献   
93.
Anaphylactic reactions after intravascular exposure to natural rubber latex (NRL) have been reported. Thus, there is an urgent need to produce medical devices with the lowest possible latex-allergen content. The latex-allergen concentration in extracts prepared from 92 lots of medical catheter (MC) balloons, manufactured by Nolato Polymer AB, Torekov, Sweden, from April 1993 to March 1996, was measured with an EAI (IgE antibody inhibition) assay. Inhibitory capacity was expressed in arbitrary units/ml (U/ml) in relation to reference NRL sap, given an arbitrary value of 1000 U. Extracts from randomly selected lots were measured for protein by the modified Lowry method. Water leaching, chlorination, and treatment with savinase were used experimentally to study reduction of the latex-allergen content. The latex-allergen content in extract from the regular MC balloons varied from 0.1 to 2.9 U/ml. All the methods used to reduce the allergen content were effective, and increased leaching stabilized the allergen content at a low level. The protein concentration of the extracts varied between 9 and 100 mg/1. No correlation was found between protein and allergen content. As a result of this study, the manufacturer has extended the stage of water leaching in the production process. This study shows that cooperation between immunologists and manufacturers may result in product development and improvement.  相似文献   
94.
The effect of intraluminal hypoxia on vascular tone and the release of prostaglandins (PG) I2 and E2 were investigated in intact isolated segments of canine femoral and coronary arteries as well as in the rat tail artery. Perfusion with hypoxic Tyrode's solution (pO2 20–40 mm Hg) evoked a marked vasodilation of the segments, precontracted with norepinephrine or serotonin. Simultaneously, a 2–3-fold increase in the release of 6-keto-PGF1 (the stable hydrolysis product of PGI2) could be observed. In parallel to 6-keto-PGF1, smaller quantities of PGE2 were released. Removal of the endothelium as well as pretreatment with indomethacin abolished both, the dilatory response and the PG-release. After administration of verapamil as well as 3,4,5-trimethoxybenzoic acid 8-diethyl-aminooctylester (TMB-8) (which binds intracellular calcium) the PG-increase was abolished and hypoxic dilatation could no longer be elicited, although the vessel had still a capacity to dilate. Exogenous administration of PGI2 and PGE2 showed that in canine femoral and coronary arteries PGI2 was the most effective vasodilating prostaglandin, while in the rat tail artery PGE2 had a 10-fold higher dilating potency compared to PGI2. At very high concentrations both PGI2 and PGE2 caused vasoconstriction. Our experiments suggest that the hypoxic endothelium-dependent dilatation may be mediated by an increased PG-release. Hypoxia-induced transmembrane calcium influx into the endothelial cells seems to be the trigger reaction.Supported by the Deutsche Forschungsgemeinschaft (Bu 436/2-1)  相似文献   
95.
Flexible treatments for intimal hyperplasia after angioplasty are still needed. The aim of this study was to demonstrate the long-term effects of vascular photodynamic therapy with talaporfin sodium on intimal hyperplasia following interventional injury. Intimal hyperplasia was induced by balloon distension injury to the carotid artery in 31 rabbits. Talaporfin, 5.0 mg/kg, was delivered systemically immediately after balloon injury. The injury site was irradiated with a diode laser light of wavelength 664 nm using a fluence of 50 J/cm2 after 30 min. At day 3 and weeks 3, 6, 9, 15, and 25 after photodynamic therapy, the treated artery of each rabbit was excised and examined immunohistochemically. Thirty minutes after talaporfin administration, drug fluorescence was found only in the balloon-injured carotid artery wall. At 3 days, no smooth muscle cells were seen in the media of the photodynamic therapy-treated arterial segments. Intimal hyperplasia developed progressively in the balloon-injured and untreated segments; however, in the segments treated with photodynamic therapy, intimal hyperplasia was markedly suppressed until 25 weeks and the media was repopulated by smooth muscle cells without macrophages. Vascular photodynamic therapy with talaporfin may be used to inhibit restenosis after vascular intervention. An erratum to this article is available at .  相似文献   
96.
目的通过动物实验评价心腔内导管超声探头对部分腹膜后脏器结构的显像效果,以及其用于腹膜后脏器显像的可行性。方法静脉鞘管引导心腔内导管超声探头进入下腔静脉,通过对8只实验犬部分腹膜后脏器的近距离超声成像,记录成像过程动物生理参数,观察其二维图像及彩色血流显像效果,并与常规经腹超声检查效果比较。结果实验前与腔内显像过程中犬的心率、动脉压、呼吸频率差异无统计学意义(P〉0.05);心腔内导管超声可清晰显示肾脏、肾上腺、大血管旁淋巴结等腹膜后脏器的二维细微结构及彩色血流分布,成像质量明显优于经腹切面的显示效果。结论采用心腔内导管超声观察腹膜后部分脏器的结构是安全可行的,成像质量明显优于经腹切面的显示效果,对肾上腺及其血供的显像尤为清晰。心腔内导管超声在腹膜后脏器显像方面有重要应用价值,为腹膜后脏器的超声检查提供了一种新方法。  相似文献   
97.
Arterial pH and blood gases were measured at intervals in conscious dogs after their first human contact of the day. Blood was sampled through an indwelling catheter in the aorta without disturbing the animals. It appeared that in the first 90 min arterial PO2, oxygen saturation and haemoglobin concentration significantly declined. PCO2 and pH changed less consistently when the acid/base status of the dogs was normal, but when a non-respiratory acidosis was present there was a significant decrease in pH and a significant increase in PCO2. Arterial pH and blood gases were also measured before and after feeding the animals. It appeared that an appreciable metabolic alkalosis developed within 2 h after a meal. The alkaline tide was accompanied by a trend to higher values for PCO2. It is concluded that, after a period of seclusion, renewed human contact causes behavioural changes in a dog, which may result in appreciable transitory changes in arterial pH and blood gas values. Blood sampling from conscious dogs should therefore take place after a proper period of habituation; preferably, a few samples should be taken at intervals to check that a steady state has been reached. If possible, blood should be collected before feeding; in any case the relationship in time of blood sampling to feeding should be constant throughout.  相似文献   
98.
目的 观察应用引导管芯做引导,更换经口气管内导管的临床效果。方法 随机选择26例已完成气管内插管的病人,将引导管芯插入气管导管内至隆突水平,并拔出气管导管;将欲更换的气管导管套在引导管芯外,在管芯引导下将气管导管插入气管内,完成换置;结果 全部病例均顺利完成更换导管,换管过程中病人氧合良好,术后未发生与更换导管相关并发症;结论 应用引导管芯更换气管内导管,方法安全,简便易行,可替代传统换管方法。  相似文献   
99.
Selective cerebral perfusion (SCP) is a better method than hypothermic circulatory arrest for brain protection in aortic arch surgery because of fewer time limitations; however; it is more troublesome during surgery. We developed a new catheter for SCP, the SP Stud catheter, with a rib-surface balloon to reduce slipping to eliminate the need for snaring or clamping. To evaluate the slipping resistance of the new catheter, we compared it with two different balloon catheters; a Foley balloon catheter with a smooth-surface balloon as long as the SP Stud catheter, and a Retro-TH catheter with a smooth-surface balloon of discoid shape half as long as the SP Stud catheter. The “draw-strength”, which refers to the slipping resistance, was measured in 20 autopsy carotid arteries in the three groups. The average draw-strengths of SP Stud catheter, foley balloon catheter, and Retro-TH catheter were 92.3±4.0, 20.8 ±1.5, and 17.9±0.8g, respectively, in sclerotic carotid arteries. The SP Stud catheter demonstrated approximately four times more resistance to slipping than the Foley balloon or Retro-TH catheters. The SP Stud catheter demonstrated a higher slipping resistance than conventional catheters, which may allow selective cerebral perfusion without snaring or clamping the carotid arteries, minimize the change of cerebral embolism, and clear the operative field.  相似文献   
100.
We report a female patient who had a scalp hemangioma, a cleft uvula, an upper sternal defect, pectus excavatum, arachnodactyly, pes planus, and joint hypermobility. She had rupture of an aortic aneurysm after minor trauma at 11 years of age. At 17 years of age, elective repair of a dilated, ectatic aorta was complicated by cerebral ischemia. Other vascular abnormalities in the proband included an aneurysm of the left subclavian artery, atresia of the right carotid artery, and calcified cerebral aneurysms. We believe that the proband's physical anomalies are best described by the PHACE (posterior fossa brain malformations, hemangiomas, arterial anomalies, coarctation of the aorta and cardiac defects, and eye abnormalities) phenotypic spectrum. This spectrum of physical anomalies also includes sternal clefting and hemagiomas as part of the sternal malformation/vascular dysplasia (SM/VD) association, as found in our patient, and the acronym PHACES has also been used. We consider that the PHACE phenotypic spectrum is likely to be broader than previously recognized and includes orofacial clefting and aortic dilatation and rupture. Our patient also had skeletal anomalies that lead to consideration of Marfan syndrome as a diagnosis. It should be recognized that there is clinical overlap between PHACE syndrome and Marfan syndrome when aortic dilatation is present. We would also like to emphasize the minor nature of the cutaneous findings in our patient despite her severe vascular complications. This is in contrast to previous reports of large or multiple hemangiomas in PHACE syndrome. Published 2002 Wiley‐Liss, Inc.  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