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21.
目的:探讨Estenia瓷树脂复合体的强度,并与其他几种树脂材料进行比较,为临床选择冠桥树脂材料提供参考。方法:采用Estenia瓷树脂复合体体外模拟下颌第一磨牙单冠和第一磨牙缺失3个单位固定桥的形态,测试单冠的抗压强度和固定桥的抗弯强度,并与Artglass、Solidex、Targis3种树脂材料在相同实验方法下测试得到的结果作比较。结果:Estenia瓷树脂单冠的折裂最大载荷均值为600.20N,Estenia瓷树脂桥的折裂最大载荷均值为302.53N。结论:Estenia瓷树脂复合体的强度高于Artglass﹑Solidex和Targis树脂复合体。 相似文献
22.
用酸蚀法提高纯钛与光固化冠桥树脂粘结强度的研究 总被引:5,自引:1,他引:4
目的:研究用酸蚀法提高钛与光固化复合树脂剪切粘结强度的可行性,并观察表面粗糙度与剪切粘结强度之间的关系。方法:采用不同浓度的酸蚀剂对钛铸件表面进行酸蚀,并与artglass光固化复合树脂进行粘结,以单纯喷砂组为对照,比较剪切粘结强度的差异。对酸蚀后及剪切试验后的金属表面进行扫描电镜观察,并测定其表面粗糙度。结果:用酸蚀法可以显著提高钛与复合树脂的粘结强度,HF浓度为4%时粘结强度最高。表面粗糙度随酸蚀剂的浓度增高而下降。结论:纯钛铸件用酸蚀法处理后可以获得较高的粘结强度,HF酸浓度以4%为宜。表面粗糙度对粘结强度不起决定性作用。 相似文献
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Vascularized osteomyocutaneous transplantation using the technique of microvascular anastomosis has shown many advantages. For the purpose of immediate reconstruction of composite defects of the mandible, 74 osteomyocutaneous flaps have been used in the last six years. They included 43 iliac osteomyocutaneous flaps pedicled to the deep circumflex iliac artery, 16 latissimus dorsi osteomyocutaneous flaps pedicled to the thoracodorsal artery and 15 pectoralis major asteomyocutaneous flaps pedicled to the acromiothoracic artery. The survival rate of the former was 90.7% (39/43), and the latter two 71% (22/31). The factors influencing the survivalrate of these osteomyocutaneous flaps have been analyzed; the complications of the recipient and donor sites have been presented; the long term results have been discussed. The authors conclude: mandibular reconstruction by using osteomyocutaneous flap grafts has the advantages of resistance to infection, fast bone healing and survival in a poorly vascularized recipient bed. The iliac osteomyocutaneous flap is better than the other two in survival ability. 相似文献
26.
用于牙科复合树脂的具有固位力外形的无机填料的研究 总被引:6,自引:0,他引:6
本文介绍了一类微细的复合式无机填料。由于具有特殊的表面结构,这类填料与复合树脂中的树脂基质之间有良好的结合力,因此称之为“具有固位力外形的无机填料”。用此类填料配制的试验性复合树脂,不仅其磨耗性能有明显的改善,而且其它机械性能也有不同程度的提高。 相似文献
27.
Stanislav Ratner P. Mona Moret Ellen Wachtel Gad Marom 《Macromolecular chemistry and physics.》2005,206(12):1183-1189
Summary: The morphology of the transcrystalline layer grown by nucleating high density polyethylene on fibers of ultra high molecular weight polyethylene was investigated by microbeam synchrotron X‐ray diffraction. Scanning with a 2 micron step size, it was possible to determine that near the fiber surface, the polymer chains of the transcrystalline layer are oriented at an angle of approx. 41° with respect to the fiber axis. This is consistent with the lamellar fold surface (the {201} plane) being close to perpendicular to the fiber axis. The X‐ray data support gradual twisting of the lamellae about the growth direction (the orthorhombic crystallite b‐axis) at a rate of ~0.85° per micron of radial distance from the fiber surface.
28.
Wayne D. Cook 《Biomaterials》1986,7(6):449-454
The spectral distributions of a range of dental photocuring sources were measured at the exit window and at a distance of 10 cm. The former enabled the evaluation of a newly proposed photocuring efficiency index which correlates well with the depth of cure of the photopolymerized resins, thus providing a basis for the comparison of different photocuring sources. The spectral irradiante of the sources obeyed the inversesquare law, allowing a comparison with the ACGIH threshold limit values. According to these criteria, no ocular hazard is posed to the patient or clinician by u.v.-A or u.v.-B radiation nor to the patient by the visible light when momentarily exposed to the sources. Similarly the ACGIH criterion indicates that the clinician does not risk chorioretinal injury provided the exposure is restricted to less than 140 s in a 3 h period. 相似文献
29.
The chemistry and structure of the dimethacrylate resins and the nature of the filler systems in dental composite resins are reviewed in relation to their influence on the setting behaviour, dimensional stability, aesthetics, fracture behaviour and adhesive potential. It is clear that a deeper understanding of the structure of the polymeric matrix and the mechanism of clinical wear is required. As a result of ongoing research in this area and with the development of dentine adhesives, the future prospects of composite resins are encouraging. 相似文献
30.
Influence of vascular parameters on the effectiveness of intra-aortic balloon pumping: A model study
The intra-aortic balloon pump has been widely used as a temporary heart-assist device. In this investigation, a nonlinear
mathematical model of the arterial system and intra-aortic balloon pump was studied analytically. Thus, the influences of
a number of vascular parameters on the effectiveness of intra-aortic balloon pumping (IABP) were determined. The effects of
changes in vascular parameters of the model on a number of performance indexes were investigated. These performance indexes
(aortic mean diastolic pressure, aortic end diastolic pressure, cardiac output, coronary flow and phase differences between
the fundamental Fourier components of aortic root pressure and flow) were used as the criterion for an evaluation of the effectiveness
of the assist pump. The following vascular parameters were perturbed by four steps (±10%, ±20%) from the values in the standard
model: heart rate, peripheral resistance, left ventricular pressure, aortic elastance, aortic radius, arterial wall thickness,
and aortic length. This model was evaluated for a wide range of balloon-pump phase-control settings (assisted case) and for
the unassisted case (when the pump is disabled). It is concluded that changes in heart rate, peripheral resistance and left
ventricular pressure cause the most significant changes in pump performance.
Dr. Ohley is with the Datascope Corporation
Dr. Kao is with the Technicare Corporation 相似文献