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1.
Guo-Quan Shi Huajun Zhu & Zhen-Guo Yan 《Communications In Computational Physics》2022,31(4):1215-1241
A priori subcell limiting approach is developed for high-order flux reconstruction/correction procedure via reconstruction (FR/CPR) methods on two-dimensional unstructured quadrilateral meshes. Firstly, a modified indicator based on
modal energy coefficients is proposed to detect troubled cells, where discontinuities
exist. Then, troubled cells are decomposed into nonuniform subcells and each subcell has one solution point. A second-order finite difference shock-capturing scheme
based on nonuniform nonlinear weighted (NNW) interpolation is constructed to perform the calculation on troubled cells while smooth cells are calculated by the CPR
method. Numerical investigations show that the proposed subcell limiting strategy on
unstructured quadrilateral meshes is robust in shock-capturing. 相似文献
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胃癌作为临床最常见的肿瘤之一,常因确诊疾病较晚而影响治疗效果,胃镜活检后的病理虽然作为确诊的金标准,但是由于此方式过程痛苦,操作复杂,费用较高,且具有侵入性,可能会导致患者拒绝操作而难普及于临床,因此积极找寻胃癌有效的监测指标十分必要。近年来,很多学者研究维生素与胃癌的相关关系,并试图通过摄取某些维生素降低胃癌发生率,延缓病情及改善预后,也有通过检测血清中维生素的水平给早期胃癌的诊断提供帮助。本文就同型半胱氨酸、维生素D、维生素C、维生素E、维生素B12及叶酸在胃癌中的作用机制,及其在血清中水平与胃癌关系的相关研究进展进行简要综述,为临床胃癌诊疗提供新思路。 相似文献
4.
《Dental materials》2022,38(9):1459-1469
ObjectiveTo evaluate the manufacturing accuracy of zirconia four-unit fixed dental prostheses (FDPs) fabricated by three different additive manufacturing technologies compared with subtractive manufacturing.MethodsA total of 79 zirconia FDPs were produced by three different manufacturing technologies, representing additive (one stereolithography [aSLA] and one material jetting [aMJ] device, two digital light processing [aDLP1/aDLP2] devices) and subtractive manufacturing (two devices [s1/s2]), the latter serving as references. After printing, additively manufactured FDPs were debound and finally sintered. Subsequently, samples were circumferentially digitized and acquired surface areas were split in three Regions Of Interest (ROIs: inner/outer shell, margin). Design and acquired data were compared for accuracy using an inspection software. Statistical evaluation was performed using the root mean square error (RMSE) and nonparametric Kruskal-Wallis method with post hoc Wilcoxon-Mann-Whitney U tests. Bonferroni correction was applied in case of multiple testing.ResultsRegardless the ROI, significant differences were observed between manufacturing technologies (P < 0.001). Subtractive manufacturing was the most accurate with no significant difference regarding the material/device (s1/s2, P > 0.054). Likewise, no statistical difference regarding accurary was found when comparing s2 with aMJ and aSLA in most ROIs (P > 0.085). In general, mean surface deviation was< 50 µm for s1/s2 and aMJ and< 100 µm for aSLA and aDLP2. aDLP1 showed surface deviations> 100 µm and was the least accurate compared to the other additive/subtractive technologies.SignificanceAdditive manufacturing represents a promising set of technologies for the manufacturing of zirconia FDPs, but not yet as accurate as subtractive manufacturing. Methodological impact on accuracy within and in between different additive technologies needs to be further investigated. 相似文献
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目的 探讨18F-氟代脱氧葡萄糖(18F-FDG)PET/CT的代谢参数及临床指标在弥漫性大B细胞淋巴瘤(DLBCL)中期评估及预后预测中的意义。方法 收集194例DLBCL患者临床资料,记录患者的中期评估结果,比较不同临床指标[β2 -微球蛋白(β2-MG)、双表达、三表达、Ann Arbor分期、淋巴瘤国际预后评分 (IPI)、多维尔5分法(D5PS)评分]和18F-FDG PET/CT代谢参数[最大标准化摄取值(SUVmax)、病灶累及部位SUVmax的总和(SUVmaxsum)、平均标准化摄取值(SUVmean)和SUVmax下降幅度(△SUVmax)]中达完全缓解(CR)者所占比例的差异,应用Cox回归和Kaplan-Meier生存分析法分析18F-FDG PET/CT代谢参数及临床指标对DCBCL患者2年无进展生存期(PFS)的影响,并对SUVmax与β2-MG、Ann Arbor分期和IPI评分进行相关性分析。结果 β2-MG > 2.3 mg/L、Ann Arbor分期Ⅲ/Ⅳ期、IPI > 2分、SUVmax > 17.00和SUVmaxsum > 38.60者达CR的比例较低;疗效达CR者△SUVmax大于未达CR者(P均 < 0.05)。Cox单因素分析显示,β2-MG、Ann Arbor分期、IPI评分、双表达、三表达、SUVmaxsum及D5PS评分均与DLBCL患者2年PFS有关(P均 < 0.05);多因素分析显示,Ann Arbor分期Ⅲ/Ⅳ期(HR = 4.486,P = 0.001)为DLBCL患者2年PFS的独立危险因素,D5PS 评分1~3分(HR = 0.256,P < 0.001)为DLBCL患者2年PFS的独立保护因素。Spearman秩相关分析显示,SUVmax与β2-MG(rs = 0.348,P = 0.001)、Ann Arbor分期(rs = 0.236,P = 0.022)和IPI评分(rs = 0.305,P = 0.003)均有关。结论 18F-FDG PET/CT的代谢参数与临床指标相关,Ann Arbor分期和D5PS可作为DLBCL患者预后的参考指标。 相似文献
8.
目的:探讨数字化及3D打印联合内镜辅助技术在颧骨颧弓骨折治疗中的应用效果。方法:选择2020年12月—2021年9月于蚌埠医学院第一附属医院行手术治疗的12例单侧颧骨颧弓骨折患者纳入研究。所有患者术前均行全头颅薄层CT检查,利用镜像反求原理对骨折部位进行模拟复位,并打印复位后的骨折模型,在模型上进行钛板预弯。术中在内镜辅助下采用前庭沟切口结合耳屏前切口对骨折断端进行解剖复位。术后所有患者均再次行全头颅薄层CT检查,将术后重建的三维模型数据与术前模拟复位的三维模型数据进行光谱融合色差对比分析,评价术后效果。结果:12例患者手术顺利,术后面部外形及功能恢复良好,无明显并发症,面部皮肤瘢痕隐蔽。术后CT与术前模拟设计光谱融合色差对比分析最大上偏差为2.998 7 mm,最大下偏差为-2.998 6 mm,平均上偏差为(0.243 0±0.025 0)mm,平均下偏差为(-0.310 0± 0.180 0)mm。结论:数字化及3D打印联合内镜辅助技术在直视下对骨折部位进行解剖复位,有助于提高骨折复位的精准度,减少术中组织损伤、术后并发症的发生,术后瘢痕隐蔽,具有良好的美观效果。 相似文献
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Kinetic Slip Boundary Condition for Isothermal Rarefied Gas Flows Through Static Non-Planar Geometries Based on the Regularized Lattice-Boltzmann Method 下载免费PDF全文
Jean-Michel Tucny David Vidal Sé bastien Leclaire & Franç ois Bertrand 《Communications In Computational Physics》2022,31(3):816-868
The simulation of rarefied gas flows through complex porous media is challenging due to the tortuous flow pathways inherent to such structures. The Lattice
Boltzmann method (LBM) has been identified as a promising avenue to solve flows
through complex geometries due to the simplicity of its scheme and its high parallel
computational efficiency. It has been proposed to model the stress-strain relationship
with the extended Navier-Stokes equations rather than attempting to directly solve
the Boltzmann equation. However, a regularization technique is required to filter out
non-resolved higher-order components with a low-order velocity scheme. Although
slip boundary conditions (BCs) have been proposed for the non-regularized multiple
relaxation time LBM (MRT-LBM) for planar geometries, previous slip BCs have never
been verified extensively with the regularization technique. In this work, following
an extensive literature review on the imposition of slip BCs for rarefied flows with the
LBM, it is proven that earlier values for kinetic parameters developed to impose slip
BCs are inaccurate for the regularized MRT-LBM and differ between the D2Q9 and
D3Q15 schemes. The error was eliminated for planar flows and good agreement between analytical solutions for arrays of cylinders and spheres was found with a wide
range of Knudsen numbers. 相似文献