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1.
托槽弓丝组合对托槽-弓丝-结扎丝结构摩擦力的影响 总被引:6,自引:2,他引:4
目的 研究不同托槽 -弓丝组合对托槽 -弓丝 -结扎丝结构摩擦力的影响。 方法 选择四种槽沟为0 .0 2 2× 0 .0 2 8″的不锈钢方丝弓托槽 (三种国产 ,一种进口 ) ,与四种不锈钢丝 (0 .4 5 mm与 0 .5 0 mm的国产圆丝、0 .0 17× 0 .0 2 5″与 0 .0 19× 0 .0 2 5″的进口方丝 )分别组合分组 ,记录托槽与弓丝间滑动时的摩擦力 ,结扎压力保持在15 0 g。 结果 国产托槽与国产圆丝组合时的摩擦力大于与进口方丝组合时的摩擦力 ,进口托槽与国产圆丝组合时的摩擦力小于与进口方丝组合时的摩擦力。 结论 在特定结扎压力下 (如 15 0 g) ,如果材质相同 ,托槽与弓丝的表面粗糙度相差越大 ,摩擦力越小 ,粗糙度越接近 ,摩擦力越大。 相似文献
2.
自酸蚀封闭剂与玻璃离子联合用于托槽粘结的临床观察 总被引:1,自引:0,他引:1
目的:评价自酸蚀粘结剂与树脂加强型玻璃离子联合用于正畸托槽粘结的临床使用效果。方法:随机选择50名患者,采用自身对照的方法进行为期12个月的临床观察。385个托槽用自酸蚀封闭剂(3MESEP)和光固化树脂加强型玻璃离子水门汀(FUJI ORTHO LC)粘结,390个托槽用京津釉质粘结剂粘结。观察托槽脱落的时间和脱落后粘结剂在牙面上的残留量,计算托槽脱落率和粘结材料残留指教。结果:光固化树脂加强型玻璃离子水门汀和自酸蚀封闭剂粘结的托槽脱落率为10.1%;京津釉质粘结剂粘结的托槽脱落率为9.0%,两者差异没有统计学意义(P〉0.05)。两种材料粘结的托槽脱落后,牙釉质上的粘结材料残留指教差异无显著统计学意义(P〉0.05)。结论:自酸蚀封闭剂和树脂加强型玻璃离子所构成的粘结技术粘结正畸托槽的粘结强度,可以满足正畸治疗的需要,在临床上有广阔的应用前景。 相似文献
3.
4.
Bernard Tandler Carlin A. Pinkstaff Alessandro Riva 《Anatomical record (Hoboken, N.J. : 2007)》1994,240(2):167-177
Background: Speciamens of human anterior lingual salivary glans obtained by surgery and by dissection of cadavers were studied ultrastructurally and histochemically. Methods: Specimens were obtained by surgery for ultrastructural study. Other specimens for histochemistry were obtained by dissection of fresh cadavers. Tissues for electron microscopy were fixed and processed by conventional mesns. Formalin-fixed cadaver specimens were subjected to a battery of tests for glycoconjugates. Results: The anterior lingual salivary glands are composed predominantly of mucous tubules (which come in two distinct sizes: large and small), seromucous demilunes, and rare seromucous acini. Regardless of tubule size, mucous cells are typically in appearance and, like mucous cells in other human salivary glands, contain filamentous bodies. Histochemically, the larger tubules contain neutral glycoproteins, low concentrations of sialoglycoproteins, and large amounts of sulfated glycoproteins. The small mucous tubules contain neutral glycoproteins, much sialoglycoprotein, and relatively small amounts of sulfated glycoprotein. The seromucous cells, whether demilunar or acinar, are identical. They contain numerous secretory granules, which show a spectrum of internal patterns from one individual to another. These cells have considerable concentrations of neutral- and sialoglycoproteins and lower concentrations of sulfated gly-coproteins. Countrary to previously published reports, we could find no differences in the ratio of mucous to seromucous cells along the anteriorposterior lingual axis: there was no gradient of seromucous cells in our specimens. The ducts in the anterior lingual salivary glands are not precise counterparts of those in the major salivary glands, since the former have no capsules, hence lack lobulation. Without these familiar structural landmarks, the only duct that can be identified with certainty is the intercalated duct, and then only if it is in continuity with or lies close to a secretory endpiece. Such ducts consist of simple cuboidal epithelium of prosaic appearance. The ductular epithelium gradually thickens and gives rise to what appear to be excretory ducts consisting of columnar cells with few mitochondria. Scattered within the walls of the walls of the larger ducts are patches of typical striated ducts wherein the taller cells display basal striations resulting from highly folded basal plasma membranes and numerous, vertically oriented, virgulate mitochondria. In other atypical regions of the excretory duct, basal cells may have a primary cilium that juts into the intercellular space. Conclusions: There is a high degree of structural variability in human anterior lingual salivary glands. Because of the technical difficulties in collecting pristine saliva from these glands, the precise functions(s) of these organs remains unknown. © 1994 Wiley-Liss, Inc. 相似文献
5.
V. B. Zakharov N. I. Berezhnova S. G. Mamontov 《Bulletin of experimental biology and medicine》1993,116(1):854-856
Translated fromByulleten' Pksperimental'noi Biologii i Meditsiny, Vol. 116, N
o
7, pp. 72–73, July, 1993 相似文献
6.
离体牙多次粘结托槽的抗张强度测定 总被引:2,自引:0,他引:2
①目的 研究牙面多次酸蚀粘结托槽抗张强度的变化。②方法 选择因正畸需要而拔除的前磨牙为实验样本 ,分为 3组 ,每组 10颗牙齿。第 1组为首次酸蚀粘结托槽 ;第 2 ,3组为第 2 ,3次酸蚀粘结托槽。以材料力学实验机分别测定其抗张强度 ,统计每一牙面上的粘结剂残留量进行ARI计分 ,并对各组进行扫描电镜观察。③结果 3组粘结托槽抗张强度比较 ,差异无显著性 (F =0 .175 ,P >0 .0 5 ) ;3组粘结剂残留指数 (ARI)计分比较 ,差异无显著性 (Hc=2 .2 38,P >0 .0 5 ) ;电镜观察 1,2次酸蚀的牙釉质表面 ,其蜂窝结构在不断增多。④结论 牙面的第 2 ,3次酸蚀粘结托槽仍能获得满意的粘结强度。 相似文献
7.
Ossification and pseudoepiphysis formation in the “nonepiphyseal” end of bones of the hands and feet
J. A. Ogden M.D. T. M. Ganey Ph.D. T. R. Light M.D. R. J. Belsole M.D. T. L. Greene M.D. 《Skeletal radiology》1994,23(1):3-13
Metacarpals, metatarsals, and phalanges were studied to assess the developmental morphology of secondary ossification in the nonepiphyseal ends of these bones as well as the formation of the pseudoepiphysis as an epiphyseal ossification variant. Both direct ossification extension from the metaphysis into the epiphysis and pseudoepiphysis formation preceded, and continued to be more mature than, formation and expansion of the classic epiphyseal (secondary) ossification center at the opposite end of each specific bone. Direct metaphyseal to epiphyseal ossification usually started centrally and expanded hemispherically, replacing both physeal and epiphyseal cartilage simultaneously. In contrast, when remnants of physis were retained, while juxtaposed epiphyseal cartilage was replaced, a pseudoepiphysis formed. There were three basic patterns of pseudoepiphysis formation. First, a central osseous bridge extended from the metaphysis across the physis into the epiphysis and subsequently expanded to create a mushroom-like osseous structure. In the second pattern a peripheral osseous bridge formed, creating either an osseous ring or an eccentric bridge between the metaphysis and the epiphysis. In the third pattern, multiple bridging occurred. In each situation the associated remnant physis lacked typical cell columns and was incapable of significantly contributing to the postnatal longitudinal growth of the involved bone. Pseudoepiphyses were well formed by 4–5 years and coalesced with the rest of the bone months of years before skeletal maturation was attained at the opposite epiphyseal end, which ossified in the typical pattern (i.e., formation of a secondary center de novo completely within the cartilaginous epiphysis). This process may also affect the development and appearance of ossification within the longitudinal epiphyseal bracket (delta phalanx). 相似文献
8.
A symptomatic case of tongue base varices in a patient with portal hypertension secondary to liver cirrhosis is presented. There are no previously documented cases in the world literature. Oesophageal varices may not be the only source of expectorated blood in a patient with portal hypertension. 相似文献
9.
三种不同处理因素下托槽粘接强度的对比 总被引:1,自引:0,他引:1
目的:研究3种不同处理因素下托槽粘接强度的化。方法:选正畸需要而拔除的60颗双尖牙为实验样本,随机分为3组,每组20颗。对每一牙面粘接标准方丝弓托槽。以材料力学实验机测定各组24 h后抗剪切强度及抗张强度,并对每一牙面上的粘接剂残留量进
行统计。结果:粘接托槽前使用抛光膏清洁牙面,能显著提高托槽粘接的抗剪切强度[非抛光组为(5.973±1.519)MP,两个抛光组分别为(9.017±3.278)和(7.862±2.437)MP,P<0 .05]。抛光膏清洁牙面后,使用光固化氟化玻璃离子复合体粘接托槽,粘接的抗剪切强度有显著提高,与京津釉质粘接剂粘接的抗剪切强度比较差异无显著性,但抗张强度较京津釉质粘接剂显著降低(P<0.05)。ARI积分比较,抛光膏清洁牙面能显著提高釉质表面与粘接剂间的粘接力(P<0.05),尤其在抗张强度组影响更显著(P<0.01)。抛光膏与光固化氟化玻璃离子复合体配合使用,抗张强度组牙釉质表面与粘接剂间的粘接力显著提高(P<0.05)。结论:牙面抛光膏及光固化氟化玻璃离子复合体可应用于正畸临床的托槽粘接。 相似文献
10.
目的:研究一种骨科患者下肢多功能防护架的研制及应用。方法:该下肢多功能防护架,包括布朗氏架,在布朗氏架上安装有烧伤架。本试验选取2013年1-10月本院住院的下肢骨折329例和膝关节术后强直患者66例,前者分为试验组169例和对照组160例,后者分为试验组34例和对照组32例。试验组采用新型下肢多功能防护架治疗,对照组则单纯采取常规治疗措施。比较各组的治疗效果。结果:下肢骨折试验组24 h内消肿止痛评分达I、II级130例(77%),对照组仅有39例(24%),试验组显著优于对照组(P〈0.05);膝关节强直术后试验组达Ⅰ、Ⅱ级28例(82%),对照组仅有12例(37%),试验组显著优于对照组(P〈0.05)。结论:新型下肢多功能防护架的应用效果较好,值得在临床上推广和应用。 相似文献