全文获取类型
收费全文 | 69162篇 |
免费 | 6963篇 |
国内免费 | 4689篇 |
专业分类
耳鼻咽喉 | 436篇 |
儿科学 | 876篇 |
妇产科学 | 496篇 |
基础医学 | 7125篇 |
口腔科学 | 1122篇 |
临床医学 | 8529篇 |
内科学 | 9281篇 |
皮肤病学 | 617篇 |
神经病学 | 3041篇 |
特种医学 | 2679篇 |
外国民族医学 | 40篇 |
外科学 | 8596篇 |
综合类 | 13960篇 |
现状与发展 | 15篇 |
一般理论 | 3篇 |
预防医学 | 5200篇 |
眼科学 | 1482篇 |
药学 | 7276篇 |
87篇 | |
中国医学 | 4632篇 |
肿瘤学 | 5321篇 |
出版年
2025年 | 25篇 |
2024年 | 1010篇 |
2023年 | 1443篇 |
2022年 | 2898篇 |
2021年 | 3621篇 |
2020年 | 2769篇 |
2019年 | 2298篇 |
2018年 | 2131篇 |
2017年 | 2175篇 |
2016年 | 1954篇 |
2015年 | 3052篇 |
2014年 | 3856篇 |
2013年 | 3769篇 |
2012年 | 5434篇 |
2011年 | 6082篇 |
2010年 | 4367篇 |
2009年 | 3613篇 |
2008年 | 4144篇 |
2007年 | 4007篇 |
2006年 | 3697篇 |
2005年 | 3360篇 |
2004年 | 2441篇 |
2003年 | 2231篇 |
2002年 | 1806篇 |
2001年 | 1437篇 |
2000年 | 1313篇 |
1999年 | 1123篇 |
1998年 | 600篇 |
1997年 | 651篇 |
1996年 | 503篇 |
1995年 | 464篇 |
1994年 | 437篇 |
1993年 | 228篇 |
1992年 | 258篇 |
1991年 | 265篇 |
1990年 | 262篇 |
1989年 | 203篇 |
1988年 | 171篇 |
1987年 | 131篇 |
1986年 | 134篇 |
1985年 | 98篇 |
1984年 | 71篇 |
1983年 | 41篇 |
1982年 | 30篇 |
1981年 | 24篇 |
1980年 | 15篇 |
1979年 | 21篇 |
1977年 | 16篇 |
1975年 | 14篇 |
1974年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
第三脑室的肿瘤手术一般需要采用枕部小脑幕入路,由于手术时间长.操作空间狭小,对手术体位的摆放要求甚高。既要充分暴露视野便于医生的手术操作.又要保护病人的神经、呼吸、循环等系统的重要生理功能,还要有利于麻醉师观察病人,避免病人神经、血管及各部位肌肉的损伤。 相似文献
152.
目的:比较不同穴位电针预处理对兔脊髓缺血再灌注损伤保护作用的效果,为临床提供最佳的预处理方案。方法:32只雄性新西兰大白兔随机数字表法分成4组(各组n=8),即对照组、戊巴比妥钠组、委中穴组及足三里穴组。对照组静脉给予生理盐水1mL/kg,连续5d;戊巴比妥钠组静脉给予戊巴比妥钠30mg/kg,连续5d;委中穴和足三里穴组每天在戊巴比妥钠(30mg/kg)麻醉下,电针分别刺激委中穴和足三里穴60min/d,连续5d。最后一次预处理后24h,夹闭肾下腹主动脉20min,制作兔脊髓缺血模型;再灌注后4,8,12,24和48h分别对动物后肢运动功能评分;再灌注48h后,深麻醉下处死动物取脊髓(L5~7),制作标本行组织病理学观察。结果:所有动物均存活,再灌注后48h电针预处理委中穴和足三里穴组后肢运动功能评分及脊髓前角运动神经元计数均明显高于对照组(P=0.001);足三里组后肢运动功能评分和脊髓前角运动神经元计数明显低于委中穴组(P=0.001);对照组与戊巴比妥钠组相比,后肢运动功能评分及脊髓前角神经元计数无显著性差别(P=1.0和P=0.873)。结论:电针预处理对兔脊髓缺血再灌注损伤有显著的保护作用,且刺激委中穴优于刺激足三里穴的效果。 相似文献
153.
Pulse pressure variation (PPV) and stroke volume variation (SVV) during mechanical ventilation have been shown to be effective parameters to predict preload responsiveness. Although induced hypertension decreases PPV and SVV, the influences of different vasopressors on PPV and SVV are unknown. 94 patients undergoing elective otologic surgery were randomly divided into three groups: Group P (patients were given phenylephrine), Group D (patients were given dopamine), Group E (patients were given ephedrine). When surgery was ongoing and the circulation state was stable, patients were given the vasopressor to increase the systolic arterial pressure (SAP) to the pre-calculated levels: low level, 10 % < ΔSAP ≤ 20 %; medium level, 20 % < ΔSAP ≤ 30 %; high level, 30 % < ΔSAP ≤ 40 %. When invasive arterial pressure reached the target value, PPV, SVV and other parameters were recorded. Dopamine decreased the PPV and SVV more significantly than ephedrine, but less significantly than phenylephrine. The influences of phenylephrine, dopamine and ephedrine on SVV and PPV are different due to their different pharmacological mechanisms. 相似文献
154.
目的探讨64层螺旋CT容积再现(VR)技术精确测量胸腔积液体积及胸腔积液各径线之间的相关性。资料与方法 64层螺旋CT检出胸腔积液26例,其中双侧胸腔积液6例,通过AW4.4工作站VR技术进行图像处理,并利用其自动容积测量工具测得胸腔积液体积(V),分析胸腔积液体积与胸腔积液最大左右径(l)、最大上下径(h)和最大前后径(d)之间的相关性。结果利用CTVR技术测得胸腔积液体积(V)为(543.66±643.81)cm3,V与d的直线回归方程:V=158.16×d-116.01(r=0.91,P<0.01)。结论利用64层螺旋CT容积再现技术测得胸腔积液体积与积液最大前后径存在明显直线相关,并可得到相应的直线回归方程。 相似文献
155.
目的:观察长期大剂量使用糖皮质激素后兔股骨头组织细胞超微结构的变化,以及激素性股骨头缺血坏死的原因。方法:实验于2002-03/2003-06在西安交通大学第二医院骨病研究所完成。健康雄性日本白兔18只,随机分为两组,实验组为12只,皮下注射醋酸氢化泼尼松8mg/kg,1次/周。对照组6只,皮下注射生理盐水0.32mL/kg,1次/。取股骨头组织苏木精-伊红染色,苏丹Ⅲ染色,周光镜下计量空缺骨陷窝数和脂肪分布。用透射电子显微镜观察股骨头各系细胞超微结构的改变。结果:实验纳入兔18只,实验过程中,实验组死亡2只,进入结果分析16只。①光镜下两组兔股骨头空缺骨陷窝量的改变:实验组第4,8,12周股骨头软骨下区的皮质下骨小梁内空缺骨陷窝较对照组增多犤21.0±2.6)%比(12.0±1.8)%,(24.0±1.8)%比(12.0±1.3)%,(36.0±1.5)%(比(13.0±2.1)%,P<0.01犦8周和12周即可见到小片块状缺失骨;第细胞的区域。②光镜下两组之间股骨头脂肪细胞的改变:实验第8,12周实验组兔股骨头内脂肪细胞明显增大,骨陷窝内有被苏丹Ⅲ染成桔黄色的脂肪沉积,两组间均未见有脂肪栓子。两组间股骨头脂肪细胞大小变化统计学上有显著性意义。③电子显微镜观察两组股骨头超微结构变化:股骨头各系细胞早期(轻者)胞浆和胞核内出现脂质堆积,晚期成骨细胞核膜碎裂染色质溶解,血管内皮细胞胞浆肿胀出现脂滴,毛细血管壁肿胀,质膜结构不完整,可见到明显的裂隙。脂肪细胞核内可见脂滴。小静脉常被异常肥大的脂肪细胞压迫,使管腔骤然变窄。结论:长期大剂量使用糖皮质激素可导致股骨头各系细胞慢性缺血缺氧引起脂肪变性,晚期发生细胞坏死。 相似文献
156.
Meng Ji Li Shen Yi-Zhe Wu Zhi-Feng Yao Jia-Sheng Yin Jia-Hui Chen Jian-Guo Jia Ling-Juan Qiao Peng Liu Jun-Bo Ge 《中华医学杂志(英文版)》2015,128(6):790-794
Background:
Renal sympathetic nerves are involved in the reflective activation of the sympathetic nervous system in circulatory control. Catheter-based renal denervation (RDN) ameliorated treatment-resistant hypertension safely, but 10%–20% of treated patients are nonresponders to radiofrequency denervation. The purpose of this study was to investigate the safety and efficiency of cryoablation for sympathetic denervation in a swine model and to explore a new way of RDN.Methods:
Seven swines randomly assigned to two groups: Renal cryoablation (CR) group and control group. The control group underwent renal angiogram only. The CR group underwent renal angiogram plus bilateral renal cryoablation. Renal angiograms via femoral were performed before denervation, after denervation and prior to the sacrifice to access the diameter of renal arterial and the pressure of aorta abdominalis. Euthanasia of the swine was performed on 28-day to access norepinephrine (NE) changes of the renal cortex and the changes of renal nerves.Results:
Cryoablation did not induce severe complications at any time point. There was no significant change in diameter of renal artery. CR reduced systolic blood pressure (BP) from 145.50 ± 9.95 mmHg at baseline to 119.00 ± 14.09 mmHg. There was a slight but insignificant decrease in diastolic BP. The main nerve changes at 28-day consisted of necrosis with perineurial fibrosis at the site of CR exposure in conjunction with the nerve vacuolation. Compared with the control group, renal tissue NE of CR group decreased by 89.85%.Conclusions:
Percutaneous catheter-based cryoablation of the renal artery is safe. CR could effectively reduce NE storing in the renal cortex, and the efficiency could be maintained 28-day at least. 相似文献157.
Bing-Bo Hou Yan Yao Ling-Min Wu Yu Qiao Li-Hui Zheng Li-Gang Ding Gang Chen Shu Zhang 《中华医学杂志(英文版)》2015,128(9):1151-1153
Background:
Nonfluoroscopic three-dimensional electroanatomical system is widely used nowadays, but X-ray remains indispensable for complex electrophysiology procedures. This study aimed to evaluate the value of optimized parameter setting and different projection position to reduce X-ray radiation dose rates.Methods:
From June 2013 to October 2013, 105 consecutive patients who underwent complex ablation were enrolled in the study. After the ablation, the radiation dose rates were measured by two different settings (default setting and optimized setting) with three projection positions (posteroanterior [PA] projection; left anterior oblique [LAO] 30° projection; and LAO 45° projection). The parameter of preset voltage, pulse width, critical voltage, peak voltage, noise reduction, edge enhancement, pulse rate, and dose per frame was modified in the optimized setting.Results:
The optimized setting reduced radiation dose rates by 87.5% (1.7 Gy/min vs. 13.6 Gy/min, P < 0.001) in PA, 87.3% (2.5 Gy/min vs. 19.7 Gy/min, P < 0.001) in LAO 30°, 85.9% (3.1 Gy/min vs. 22.1 Gy/min, P < 0.001) in LAO 45°. Increase the angle of projection position will increase the radiation dose rate.Conclusions:
We can reduce X-ray radiation dose rates by adjusting the parameter setting of X-ray system. Avoiding oblique projection of large angle is another way to reduce X-ray radiation dose rates. 相似文献158.
Background:The clinical failure after prostatic artery embolization (PAE) with conventional particles was relatively high,in treatment for lower urinary tract symptoms (LUTS) due to benign prostatic hy... 相似文献
159.
Ye Yao Wei Wei Jing Sun Linjun Chen Xiaohui Deng Liyuan Ma Siguo Hao 《European journal of medical research》2015,20(1)
Background
Exosomes secreted by tumor cells contain specific antigens that may have immunotherapeutic purposes. The aim of this study was to characterize the proteomic content of lymphoma cell-derived exosomes (LCEXs).Methods
In this study, exosomes derived from Raji cells (EXORaji) were purified and proteins of EXORaji were separated by one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. Protein bands were identified by mass spectrometry. The protein components of EXORaji were analyzed using shotgun technology, and the function proteins of EXORaji were defined and described using the Gene Ontology (GO) database and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis.Results
A total of 197 proteins were identified in EXORaji; 139 proteins were also identified in Raji cells, showing an overlap of 70.56% of the total proteins in EXORaji. Interestingly, the remaining 58 proteins were unique to EXORaji. The GO database and KEGG were used to define and describe the function of proteins. The data showed that some important proteins involved in antigen procession and presentation as well as cell migration and adhesion were also identified in EXORaji, such as MHC-I and II, HSC70, HSP90, and ICMA-1.Conclusions
LCEXs express a discrete set of proteins involved in antigen presentation and cell migration and adhesion, suggesting that LCEXs play an important role in the regulation of immunity and interaction between lymphoma cells and their microenvironment. LCEXs harbor most of the proteins of lymphoma cells and could be one of the sources of lymphoma-associated antigens for immunotherapeutic purposes. 相似文献160.
Fangxin Zhang Wenming Wu Zhiyun Deng Xiaofeng Zheng Jiucong Zhang Shangxin Deng Jiayu Chen Qiang Ma Yong Wang Xiaohui Yu Shengchao Kang Xiufeng Wang 《International journal of clinical and experimental pathology》2015,8(5):5189-5195
Background: The failure of intestinal mucosal barrier may induce multiple organ dysfunction and systemic inflammatory response syndrome, but little work has been done on whether hypobaric hypoxia related to the failure of intestinal mucosal barrier. Aims: To study the expression of hypoxia-inducible factor 1α (HIF-1α), inducible nitric oxide synthase (iNOS) and morphological changes of intestinal mucosa in albino rats at different altitude. Methods: 30 male Wistar rats raised in plain for one month were randomly divided into 3 groups: Plain 500 m group (n=10), High-altitude (HA) 3842 m group (n=10) and HA4767 m group (n=10). Each group was delivered to different altitude area at the same shipping time and executed after 3 days’ exposure to different altitude. Intestinal segments with the same location of all rats were removed for morphological analyses. Morphologic parameters (villous height, crypt depth, mucosal wall thickness and villous surface area) were measured by optical and scanning electron microscope. The expression of iNOS and HIF-1α were detected by immunohistochemistry. Results: Morphological indexes in higher altitude groups were exacerbated obviously compared with those of lower altitude groups. While the expression of iNOS and HIF-1α in higher altitude groups were significantly increased than those of lower altitude groups. Linear correlation analysis showed that the expression of iNOS was positively correlated with that of HIF-1α. Conclusions: Hypobaric hypoxia increases the expression of HIF-1α and iNOS in intestinal mucosa, however exacerbates the mucous morphologic parameters with altitude increasing. HIF-1α may regulate the expression of iNOS and be involved in the damage of intestinal mucosa. 相似文献