全文获取类型
收费全文 | 48503篇 |
免费 | 3265篇 |
国内免费 | 212篇 |
专业分类
耳鼻咽喉 | 580篇 |
儿科学 | 1207篇 |
妇产科学 | 1007篇 |
基础医学 | 6797篇 |
口腔科学 | 3187篇 |
临床医学 | 3950篇 |
内科学 | 10826篇 |
皮肤病学 | 1072篇 |
神经病学 | 3969篇 |
特种医学 | 1088篇 |
外国民族医学 | 1篇 |
外科学 | 6490篇 |
综合类 | 485篇 |
一般理论 | 15篇 |
预防医学 | 4449篇 |
眼科学 | 1026篇 |
药学 | 3116篇 |
1篇 | |
中国医学 | 327篇 |
肿瘤学 | 2387篇 |
出版年
2023年 | 437篇 |
2022年 | 976篇 |
2021年 | 1820篇 |
2020年 | 1136篇 |
2019年 | 1568篇 |
2018年 | 1877篇 |
2017年 | 1244篇 |
2016年 | 1336篇 |
2015年 | 1587篇 |
2014年 | 2085篇 |
2013年 | 2529篇 |
2012年 | 3986篇 |
2011年 | 4247篇 |
2010年 | 2236篇 |
2009年 | 1812篇 |
2008年 | 2998篇 |
2007年 | 2960篇 |
2006年 | 2685篇 |
2005年 | 2298篇 |
2004年 | 2011篇 |
2003年 | 1742篇 |
2002年 | 1581篇 |
2001年 | 655篇 |
2000年 | 688篇 |
1999年 | 615篇 |
1998年 | 348篇 |
1997年 | 246篇 |
1996年 | 232篇 |
1995年 | 237篇 |
1994年 | 201篇 |
1993年 | 185篇 |
1992年 | 302篇 |
1991年 | 264篇 |
1990年 | 243篇 |
1989年 | 236篇 |
1988年 | 220篇 |
1987年 | 171篇 |
1986年 | 166篇 |
1985年 | 156篇 |
1984年 | 154篇 |
1983年 | 126篇 |
1982年 | 98篇 |
1981年 | 101篇 |
1979年 | 115篇 |
1978年 | 104篇 |
1977年 | 75篇 |
1975年 | 72篇 |
1974年 | 83篇 |
1973年 | 84篇 |
1970年 | 73篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Anya Pimentel Gomes Fernandes Vieira Jose Maria Sampaio Meneses Jr Renato Luiz Maia 《Journal of oral pathology & medicine》2007,36(2):117-119
Cementoblastomas are benign lesions of the odontogenic ectomesenchyme that rarely occur related to the primary dentition, especially on the left side of the mandible. This study describes a case of a true cementoblastoma related to the left second primary mandibular molar in a 7-year-old child (the largest one seen in the left side of the mandible). Additionally, the radiographic and histologic findings of the lesion are described in details. 相似文献
82.
Mariana Diniz Bisi Santos Arthur Braga Pfeifer Marcos Rogério Pupo Silva Claudio Luiz Sendyk WIlson Roberto Sendyk 《Journal of applied oral science : revista FOB》2007,15(2):148-151
One of the causes of implant failures in cemented implant-retained prostheses is the fracture of abutment screw or UCLA abutment. This article reports a case of simultaneous fracture of two UCLA abutments screws occurring in an implant-supported prosthesis placed in the mandibular molar region. The fractured structures were examined under scanning electron microscopy to investigate the probable causes of the failure, which were not related to failures on materials or fabrication of the screws, but rather were due to shear forces. The misfit in cemented prostheses may be the most likely cause of shear force generation. 相似文献
83.
Jose S. Pulido Ikuko Sugaya Jordan Comstock Kiminobu Sugaya 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2007,245(6):889-893
Purpose Reelin is important in the guidance of neuronal stem cells in the central nervous system during normal development. We wished
to determine whether reelin is expressed in the retina and cornea after injury.
Methods Mice underwent laceration of their retina as well as corneal epithelial debridement. The mice were sacrificed at 3 days, and
eyes were fixed and stained for reelin expression and reelin messenger ribonucleic acid (mRNA).
Results In normal eyes, reelin was expressed only at very low levels in the ganglion cell layer of the retina and the endothelial
cell layer of the cornea. In injured eyes, there was marked expression in reelin immunoreactivity in the retina and cornea.
Reelin gene expression was seen in the retina and cornea.
Conclusions Reelin is expressed during normal retinogenesis. This study shows that reelin is also upregulated following injury to the
retina and cornea. The expression of reelin following injury suggests that reelin may play an important role in regulating
stem cell trafficking in neuronal and nonneuronal tissues following injury similar to its role in normal organogenesis.
For consideration of publication in Graefe’s Archive for Clinical and Experimental Ophthalmology. 相似文献
84.
85.
Jose Sanchez-Chapula Alejandro Elizalde 《Naunyn-Schmiedeberg's archives of pharmacology》1987,336(2):218-223
Summary The effects of histamine on the transmembrane electrical activity of cells of small preparations (0.5 × 0.5 mm) of guinea-pig and rabbit sinoatrial- and atrioventricular-nodes were studied. Histamine at concentrations above 10–7 mol/l increased the firing rate, the rate of diastolic depolarization, the maximum diastolic potential, the amplitude and the maximum rate of depolarization of the action potential of pacemaker cells of rabbit and guineapig sinoatrial cells and rabbit atrioventricular cells. These effects were antagonized by the HZ-receptor blocker cimetidine (2.5 × 10–6 mol/1) but they were not modified by the H1-receptor blocker chlorphenamine (2.5 and 5×10–6 mol/1). Small preparations of guinea-pig atrioventricular node did not exhibit spontaneous activity, but it was induced by histamine and blocked by cimetidine. Histamine increased the maximum upstroke velocity of propagated action potential of cells of the central part of complete atrioventricular node in both species studied. These effects were blocked by cimetidine, but not by chlorphenamine. It is concluded that the increase in automaticity induced by histamine in guinea-pig and rabbit sinoatrial and atrioventricular nodes was due to stimulation of H2receptors. Histamine did not depress electrical activity of atrioventricular node cells, but rather increased it. This effect was due to H2-receptor stimulation.
Send offprint requests to: J. Sanchez-Chapula at the above address 相似文献
86.
M Salim-Hanna A M Edwards E Silva 《International journal for vitamin and nutrition research. Internationale Zeitschrift für Vitamin- und Ern?hrungsforschung. Journal international de vitaminologie et de nutrition》1987,57(2):155-159
Studies in animals have suggested that the products of the irradiation of tryptophan in the presence of riboflavin may play a role in the development of hepatic dysfunction during parenteral nutrition. In this paper we describe the formation of an adduct between tryptophan and riboflavin obtained as a consequence of an anaerobic irradiation of these compounds. Through the use of molecular sieves and of an ion-exchange resin it was possible to separate the photo-adduct from the dimer riboflavin and other reaction products. The various fractions were characterized on the basis of their absorption and emission spectra. Also used were measures of anisotropy of fluorescence emission in order to characterize the derived adduct. 相似文献
87.
88.
89.
F. M. O. Silva J. E. Vergara‐Parente J. K. N. Gomes M. N. Teixeira R. P. Lima 《Transboundary and Emerging Diseases》2007,54(3):119-122
Serum chemistry analyses represents a fundamental tool for the diagnosis and understanding of diseases in marine mammals. Although several studies are being conducted within the field of clinical pathology, haematological and serum chemistry data for Antillean manatees are deficient. The purpose of this study was to determine serum chemistry values for captive Antillean manatees within the CMA/Ibama facility in Brazil. Serum samples were obtained from five captive adult Antillean manatees fed with seagrass and analysed for aspartate aminotransferase, alanine aminotransferase, bilirubin, alkaline phosphatase, urea, creatinine, glucose, triglycerides, cholesterol, total protein, albumin, globulin, phosphate, chloride, calcium and uric acid. Blood chemistry parameters were determined using a semi‐automatic analyzer. Maximum, minimum, mean and standard deviations were calculated for each serum chemistry parameter. Differences on the values of males and females were verified using an unpaired Student's t‐test. All the parameters analysed were similar between sexes, with exception of AP, which was higher in females (191.43 ± 31.86 U/l). Alanine aminotransferase and uric acid values for Trichechus manatus manatus are reported for the first time in this paper. This study is the first to report serum chemistry parameter values for long‐term captive male and female Antillean manatees. Therefore, the lower values of albumin, phosphate, chloride, cholesterol and triglycerides obtained here highlight the importance of clinical pathology during health monitoring of captive marine mammals. 相似文献
90.