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   3812篇
  免费   187篇
  国内免费   71篇
耳鼻咽喉   43篇
儿科学   10篇
妇产科学   156篇
基础医学   371篇
口腔科学   627篇
临床医学   187篇
内科学   119篇
皮肤病学   10篇
神经病学   109篇
特种医学   67篇
外科学   1483篇
综合类   435篇
现状与发展   1篇
预防医学   128篇
眼科学   21篇
药学   237篇
  1篇
中国医学   28篇
肿瘤学   37篇
  2024年   6篇
  2023年   71篇
  2022年   101篇
  2021年   159篇
  2020年   167篇
  2019年   111篇
  2018年   151篇
  2017年   108篇
  2016年   135篇
  2015年   153篇
  2014年   272篇
  2013年   249篇
  2012年   211篇
  2011年   265篇
  2010年   209篇
  2009年   239篇
  2008年   207篇
  2007年   198篇
  2006年   185篇
  2005年   176篇
  2004年   156篇
  2003年   101篇
  2002年   85篇
  2001年   72篇
  2000年   49篇
  1999年   30篇
  1998年   38篇
  1997年   32篇
  1996年   20篇
  1995年   13篇
  1994年   16篇
  1993年   8篇
  1992年   12篇
  1991年   9篇
  1990年   5篇
  1989年   5篇
  1988年   5篇
  1987年   2篇
  1986年   5篇
  1985年   7篇
  1984年   4篇
  1983年   4篇
  1982年   6篇
  1981年   3篇
  1980年   3篇
  1979年   4篇
  1978年   1篇
  1977年   1篇
  1973年   1篇
排序方式: 共有4070条查询结果,搜索用时 15 毫秒
51.
目的评价植入镍钛记忆合金微创融合器(NiTi-TFC/C)的颈椎节段的稳定性及压缩力学性能。方法采集24只羊颈椎标本随机分为4组,每组6份,四组处理分别为:单取髓核组、自体髂骨植骨组、微创融合器组和钛制融合器组(InterFix)。所有标本进行前路减压,并对后3组进行椎间融合术。分别对各组标本进行生物力学测试并进行比较。结果微创融合器组与钛制融合器组在强度、刚度及扭转力学等方面无显著性差异(P>0.05)。而微创融合器组与自体髂骨植骨组具有显著性差异(P<0.05)。最大承载力为12050N。结论该微创融合器强度大、刚度高、抗扭转能力强,具有良好的抗压能力,为颈椎融合提供新型的融合装置。  相似文献   
52.
P Ducheyne 《Biomaterials》1983,4(3):185-191
As a first part of a biocompatibility testing programme, in vitro corrosion tests were carried out on porous stainless steel AISI 316L and titanium compacts made of 100 microns thick fibres. The present porous metal structures are used as coatings on permanent orthopaedic implants; with osseous tissue invading the pores, the implant becomes securely anchored to the surrounding bone. The results show that no inadvertent reactions occur with porous titanium. It can probably be used with no greater risk of localized electrochemical attack than the parent bulk material.  相似文献   
53.
目的探讨头皮合并颅骨缺损的修复方法。方法对2000年至2007年治疗的6例头皮合并颅骨缺损患者,采用皮肤扩张术修复头皮,钛网修补颅骨缺损。结果6例患者中,1例患者出现皮瓣下积液,经抽吸、加压包扎后愈合;其余病例未出现感染、血肿及皮瓣坏死等并发症,外观满意。结论皮肤扩张术和钛网联合应用是修复头皮合并颅骨缺损的较好方法。  相似文献   
54.
目的:观察钛表面纳米仿生磷灰石涂层对成骨样细胞行为的影响,为骨科常用钛植入体的表面改性及其生物效应提供实验依据。方法: 商业用纯钛经过物理、化学和生物处理,表面生成均匀薄层仿生的纳米磷灰石涂层,将仿生涂层的钛金属板与成骨样细胞复合培养,以纯钛和只经磨砂、酸蚀处理的钛板作为对照,采用MTT法检测细胞活力和增殖变化、扫描电镜和激光共聚焦荧光显微镜观察细胞形态、RT-PCR检测碱性磷酸酶基因表达。结果: 纳米仿生磷灰石涂层比非涂层钛金属表面细胞的增殖数量明显增高,细胞的形态和分布也优于对照组;培养12 d,涂层对细胞ALP基因表达的量明显高于对照组。结论: 钛金属表面纳米仿生磷灰石涂层可以增强细胞的生物效应,提高钛植入体的骨界面早期结合,具有很好的应用前景。  相似文献   
55.
华玲  万荣辉  郭军 《医学信息》2006,19(3):497-498
目的总结弛环充填式无张力修补术治疗老年腹股沟疝患者的经验。方法回顾分析2002年3月-2005年7月采用德国Braun公司生产的Braun mesh和plug治疗的86例老年腹股沟疝患者的临床资料。结果平均手术时间35min,术后8-10h下床活动,2周恢复日常生活,伤口均一期愈合,术后尿潴留15例,异物感3例,随访3—40个月无一例复发。结论疝环充填式无张力修补术操作方便,创伤小,恢复快,复发率低,是老年患者理想有效的疝修补术。  相似文献   
56.
Endoprostheses made from knitted fabric of 3 loop types were used for hernioplasty in rats. Biocompatibility of implanted textile constructions was evaluated after 6 months. The intensity of inflammatory reaction and types of complications in animals depended on the loop type and method of finishing of the mesh endoprosthesis tissue. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 145, No. 5, pp. 582–587, May, 2008  相似文献   
57.
We hypothesized that walking at increased speed or increasing gradient might have different effects on chest wall kinematics and respiratory muscle power components, and contribute differently to respiratory effort sensation. We measured the volumes of chest wall compartments by optoelectronic plethysmography, esophageal, gastric and transdiaphragmatic (P di) pressures, and the sensation of the respiratory effort by a Borg scale in five normal subjects walking both at ascending gradient with constant speed (AG) and at ascending speed with constant gradient (AS). Chest wall kinematics, evaluated by displacement of chest wall compartments, did not show any significant difference between AS and AG. Muscle power, calculated as the product of mean flow and mean pressure, increased similarly, but its partitioning into pressure and velocity of shortening differed in the two modes. A greater increase in the pressure developed by the abdominal muscles (P abm) (4.06-fold), and in the velocity of shortening of both rib cage inspiratory muscles (v rcm,i) (2.01-fold) and the diaphragm (v di) (1.90-fold) was associated with a lower increase in the pressure developed by the rib cage inspiratory muscles (P rcm,i) (1.24-fold) and P di (0.99-fold) with AG. Instead, with AS, a lower increase in P abm (2.12-fold), v rcm,i (1.66-fold) and v di (1.54-fold) was associated with a greater increase in P rcm,i (1.56-fold) and P di (1.97-fold). A combination of P abm and v di during AG (Wald 2=23.19, P<0.0000), with the addition of P rcm,i during AS (Wald 2=29.46, P<0.0000), was the best predictor of Borg score. In conclusion, the general strategy adopted by respiratory centers during different walking modes does not differ in terms of ventilation, chest wall kinematics, and respiratory muscle power production, whereas it does in terms of partitioning of power into pressure and velocity of shortening, and respiratory muscle contribution to respiratory effort sensation. Combinations of different patterns of flow and pressure generation made the respiratory effort sensation similar during AS and AG modes.  相似文献   
58.
Infection of rabbits with erythrogenic toxin producing streptococcal strains caused a marked increase of humoral antibodies, which was detected by immunoprecipitation and ELISA. An antibody response directed towards the erythrogenic toxin type A was demonstrated by fused rocket immunoelectrophoresis. All toxinogenic reference strains produced ET type A under in vivo conditions despite that this toxin was not always demonstrated under in vitro conditions. The infection resulted in an increase of mitogenic response of peripheral lymphocytes to the initial nonspecific mitogenic erythrogenic toxins, whereas the Con A stimulation was depressed starting 14 days after infection and lasting during a period of 90 days. Since a normal antibody response was evoked, it seems likely that the T helper cell function was not affected.  相似文献   
59.
Tissue cages implanted subcutaneously were used to infect rabbits with erythrogenic toxin (ET) producing streptococci. The in-vivo production of ET was followed during the infection by immunoprecipitation analyses of the tissue cage fluid (TCF). ET types A and C were mainly detected during the first week of infection, but, as late as 4 weeks after the inoculation, ET was occasionally found in TCF. The nonspecific mitogenic activity of ET on human lymphocytes was also used as a biological marker to recognize ET in TCF. Mitogenic activity was detected in 90% of samples during the first week. In order to characterize the mitogenic material released by growing streptococci, TCF was electrofocused in polyacrylamide gel. The eluates of sliced gels were checked for mitogenic activity and compared with a purified ET preparation containing ET types A and C. It could be verified that ET type A was produced under in-vivo conditions by strains NY-5 and SF130, while ET type C was produced by strain T18. Differences between production of toxins in vitro and in vivo might be of significance for the understanding of the pathogenetic mechanisms in streptococcal infection.  相似文献   
60.
Optoelectronic plethysmography (OEP) has been shown to be a reliable method for the analysis of chest wall kinematics partitioned into pulmonary rib cage, abdominal rib cage, abdomen, and right and left side in the seated and erect positions. In this paper, we extended the applicability of this method to the supine and prone positions, typically adopted in critically ill patients. For this purpose we have first developed proper geometrical and mathematical models of the chest wall which are able to provide consistent and reliable estimations of total and compartmental volume variations in these positions suitable for clinical settings. Then we compared chest wall (CW) volume changes computed from OEP( V CW) with lung volume changes measured with a water seal spirometer (SP) ( V SP)in 10 normal subjects during quiet (QB) and deep (DB) breathing on rigid and soft supports. We found that on a rigid support the average differences between V SP and V CW were –4.2% ± 6.2%, –3.0% ± 6.1%, –1.7% ±7.0%, and –4.5% ± 9.8%, respectively, during supine/QB, supine/DB, prone/QB, and prone/DB. On the soft surface we obtained –0.1% ± 6.0%, –1.8% ± 7.8%, 18.0% ± 11.7%, and 10.2% ± 9.6%, respectively. On rigid support and QB, the abdominal compartment contributed most of the V CW in the supine (63.1% ± 11.4%) and prone (53.5% ± 13.1%) positions. V CW was equally distributed between right and left sides. In the prone position we found a different chest wall volume distribution between pulmonary and abdominal rib cage (22.1% ± 8.6% and 24.4% ± 6.8, respectively) compared with the supine position (23.3% ± 9.3% and 13.6% ± 3.0%). © 2001 Biomedical Engineering Society. PAC01: 8763Lk, 8719Uv  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