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BackgroundAnteriorly-loaded walking is common in many occupations and may increase fall risk. Dynamic gait stability, defined by the Feasible Stability Region (FSR) theory, quantifies the kinematic relationship between the body’s center of mass (COM) and base of support (BOS). FSR-based dynamic gait stability has been used to evaluate the fall risk.Research questionHow does front load carriage affect dynamic gait stability, step length, and trunk angle among young adults during treadmill walking?MethodsIn this between-subject design study, 30 healthy young adults were evenly randomized into three load groups (0%, 10%, or 20% of body weight). Participants carried their assigned load while walking on a treadmill at a speed of 1.2 m/s. Body kinematics were collected during treadmill walking. Dynamic gait stability (the primary variable) was calculated for two gait events: touchdown and liftoff. Step length and trunk angle were measured as secondary variables. One-way analysis of variance was conducted to detect any group-related differences for all variables. Post-hoc analysis with Bonferroni correction was performed when main group differences were found.ResultsNo significant differences but medium to large effect sizes were found between groups for dynamic gait stability at touchdown (p = 0.194, η2 = 0.114) and liftoff (p = 0.122, η2 = 0.139). Trunk angle significantly increased (indicating backward lean) with the front load at touchdown (p < 0.001, η2 = 0.648) and liftoff (p < 0.001, η2 = 0.543). No significant between-group difference was found related to the step length (p = 0.344, η2 = 0.076).SignificanceCarrying a front load during walking significantly alters the trunk orientation and may change the COM-BOS kinematic relationship and, therefore, fall risk. The findings could inform the design of future studies focusing on the impact of anterior load carriage on fall risk during different locomotion.  相似文献   
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目的:探讨大负荷运动后大鼠骨骼肌时钟基因Bmal1节律振荡变化及其对线粒体结构功能的调控作用。方法:将156只成年SD大鼠随机分为对照组和运动组,运动组予以一次大负荷运动训练。每6 h取各组大鼠腓肠肌,使用RT-qPCR检测各时相时钟基因Bmal1的mRNA水平,并用余弦分析软件CircaCompare(R Packages)获取拟合余弦曲线参数,分析时钟基因Bmal1的mRNA表达节律性振荡情况,透射电镜下观察每周期始末(ZT0、ZT24、ZT48和ZT72)骨骼肌线粒体的形态学变化,Western blot检测Bmal1和过氧化物酶体增殖物激活受体γ辅激活因子1α(peroxisome proliferator activated receptorγcoactivator-1α,PGC-1α)的蛋白表达,ELISA测定ATP和ADP含量,以及线粒体氧化呼吸链酶细胞色素C氧化酶复合物亚单位Ⅱ(subunitsⅡof cytochrome C oxidase complex,COXⅡ)和COXⅣ的活性。结果:运动组Bmal1的mRNA表达在ZT0~ZT24时节律出现紊乱(P>0.05),ZT24~ZT48和ZT48~ZT72时节律恢复(P<0.05)。大负荷运动后运动组线粒体形态于ZT0出现肿胀、嵴结构损伤等异常,于ZT24和ZT48时有所恢复,ZT72时损伤基本消失。与对照组相比,运动组Bmal1、PGC-1α的蛋白表达于ZT0时显著升高(P<0.05),ATP和ADP含量分别于ZT0时显著下降和升高(P<0.05),COXⅡ和COXⅣ活性于ZT0时显著升高和下降(P<0.05),在ZT24时二者活性下降至最低(P<0.05)。结论:大负荷运动可诱发骨骼肌时钟基因Bmal1的节律紊乱,可能参与调控了线粒体的结构功能异常。  相似文献   
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目的探讨脑小血管病(cerebral small vessel disease,CSVD)认知障碍特点及与影像学总负荷评分的关系。方法采用横断面调查,纳入2016-10—2019-12中山市中医院就诊的脑小血管病患者272例,以MMSE评分进行分组,同时纳入年龄、性别、受教育程度匹配的健康志愿者30例,采集各组人口学信息及血管病危险因素,磁共振检查评价脑小血管病总体负荷评分,利用MoCA量表评估认知水平。结果 CSVD无认知障碍组118例,认知障碍组154例,2组受教育年限、既往卒中病史方面差异有统计学意义(P<0.05)。各组MoCA总分存在显著差异,认知障碍组视空间及执行功能、记忆、语言、注意、计算方面,评分明显下降(P<0.05)。以总负荷评分对CSVD患者进行分类,总负荷评分1~2分主要分布于无认知障碍(97.46%)和轻中度认知障碍(76.11%)患者,3~4分则主要分布于重度认知障碍(87.80%)患者,差异有统计学意义(P<0.01)。进一步MoCA认知域评价,在总负荷评分≥1分出现视空间及执行、注意下降,当评分≥3分时认知域受累增多,评分明显降低,出现视空间与执行、记忆、语言、注意力、抽象、计算等多个认知域损害(P<0.05)。结论 CSVD相关认知功能障碍以视空间及执行功能受累为特点,随影像学负荷评分增加,认知功能障碍受损加重。  相似文献   
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目的:分析不同选穴、留针时间、针刺深度对原发性高血压患者24 h血压负荷及昼夜节律的影响,优选最佳针刺降压方案。方法:纳入48例临床病例,采用正交试验设计,按照3因素2水平,即选穴(人迎、太冲)、留针时间(15、30 min)、针刺深度(浅刺、深刺),分为8组,每组6例,观察针刺前后24 h动态血压负荷及血压昼夜节律的变化。结果:(1)针刺深度对收缩压负荷的影响最为显著(P<0.05),各因素不同水平的影响程度为:人迎>太冲,15 min<30 min,浅刺<深刺,最佳调节收缩压方案为深刺人迎30 min;(2)留针时间对舒张压负荷的影响最为显著(P<0.05),各因素不同水平的影响程度为:人迎<太冲,15 min<30 min,浅刺<深刺,最佳调节舒张压方案为深刺太冲30 min;(3)不同因素对于昼夜节律的影响程度为针刺深度>留针时间>选穴;各因素不同水平对昼夜节律的影响程度为:人迎<太冲,15 min<30 min,浅刺<深刺。最佳调节昼夜节律的方案为深刺太冲30 min。结论:深刺人迎或太冲30 min为针刺调节收缩压负荷、舒张压负荷及血压昼夜节律的最佳方案。  相似文献   
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The aim of this study was to analyse the effect of zirconia and titanium surfaces on biofilm formation and host-derived parameters. Studies comparing zirconia and titanium surfaces were selected up to September 1, 2019. The outcome measures were surface roughness, contact angle, bacterial count, bacterial adherence, biofilm thickness, bacterial distribution, and specifically investigated biofilm and specific host-derived immunological parameters. Random-effects meta-analyses of in vitro and in vivo studies were conducted. A total of 39 studies were included for data extraction. In the systematic review data, 10 studies stated that zirconia accumulated less initial oral biofilm parameters, 16 investigations showed negligible inter-material differences, and only one study showed that zirconia attracted the most biofilm. However, in the meta-analysis, the bacterial coverage was found to be significantly superior for zirconia surfaces (P <  0.00001); the other outcome measures did not show any statistically significant differences between zirconia and titanium for the remaining parameters and the studies presented a substantial degree of heterogeneity. Overall, on the basis of the meta-analysis, the current data situation does not allow a clear preference for the use of zirconia or titanium.  相似文献   
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In this paper, the stability of large-size graded crushed stone used for road base or cushioning under repeated load is investigated. Using an in-house developed device, large-size crushed stone mix was compacted and molded by the vibration and rotary compaction method. Cyclic rotating axial compression was applied, and the shakedown theory was used to study the cumulative deformation of the large-size crushed stone specimens. The effects of gradation parameters on the cumulative strain and stability behavior were analyzed, and the critical stability and failure loads were determined according to the shakedown theory. The test results indicate that there are three obvious instability behavior stages of large-size graded crushed stone under cyclic rotating axial compression: elastic stability, plastic creep, and incremental plastic failure. Large-size graded crushed stone has a higher critical stability load stiffness than conventional-size graded crushed stone. The critical shakedown load of the specimen is mainly affected by the skeleton structure performance, and the critical failure load by the properties of the crushed stone material. Increasing the content and compactness of large-size crushed stone in the specimen can improve the stiffness and stability performance, and to achieve improvements, the content of large-size crushed stone should be controlled between 22% and 26%. The critical shakedown load increases with the increase in the California bearing ratio (CBR) value, while, on the other hand, the CBR value has little relationship with the critical failure load.  相似文献   
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