全文获取类型
收费全文 | 3728篇 |
免费 | 243篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 44篇 |
儿科学 | 121篇 |
妇产科学 | 116篇 |
基础医学 | 619篇 |
口腔科学 | 259篇 |
临床医学 | 306篇 |
内科学 | 758篇 |
皮肤病学 | 117篇 |
神经病学 | 307篇 |
特种医学 | 97篇 |
外科学 | 307篇 |
综合类 | 16篇 |
一般理论 | 2篇 |
预防医学 | 404篇 |
眼科学 | 73篇 |
药学 | 231篇 |
中国医学 | 19篇 |
肿瘤学 | 203篇 |
出版年
2024年 | 3篇 |
2023年 | 39篇 |
2022年 | 76篇 |
2021年 | 185篇 |
2020年 | 84篇 |
2019年 | 119篇 |
2018年 | 186篇 |
2017年 | 97篇 |
2016年 | 109篇 |
2015年 | 144篇 |
2014年 | 193篇 |
2013年 | 213篇 |
2012年 | 279篇 |
2011年 | 338篇 |
2010年 | 194篇 |
2009年 | 141篇 |
2008年 | 208篇 |
2007年 | 221篇 |
2006年 | 189篇 |
2005年 | 160篇 |
2004年 | 174篇 |
2003年 | 151篇 |
2002年 | 120篇 |
2001年 | 46篇 |
2000年 | 44篇 |
1999年 | 37篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 18篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 24篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1966年 | 2篇 |
排序方式: 共有3999条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Transplacental IgG Subclass Concentrations in Pregnancies at Risk of Haemolytic Disease of the Newborn 总被引:5,自引:0,他引:5
A. Lubenko Marcela Contreras C.H. Rodeck U. Nicolini Julia Savage and H. Chana 《Vox sanguinis》1994,67(3):291-298
The relationship of haemolytic disease of the newborn (HDN) to the transplacental passage of the four IgG subclasses was assessed at varous gestational ages by comparing the maternal and fetal IgG subclass concentrations in 34 pregnancies at risk of HDN with those in 30 pregnancies not at risk. Higher maternal and fetal IgG1 levels were attained in pregnancies at risk of HDN than in pregnancies not at risk. In contrast, a slight decrease in maternal IgG2 and IgG4 levels occurred in pregnancies at risk of HDN, as compared with a slight rise in maternal IgG2 and IgG4 levels in pregnancies not at risk of HDN. Changes in fetal IgG2 and 4 concentrations in either type of pregnancy were very similar, showing only slight increases between the 19th and 34th week of gestation. A slight decrease in maternal IgG3 occurred in both types of pregnancy. In contrast, higher and fairly steady levels of fetal IgG3 were observed in fetuses not at risk of HDN throughout gestation, when compared with those in 'at risk' pregnancies. However, the statistical reliability of these results is not clear since only small numbers of samples were tested and because wide variations in IgG concentrations were observed. The IgG subclass concentrations in 50 paired maternal and cord blood samples were also measured and revealed that IgG1 levels were substantially higher in cord rather than maternal blood; cord and maternal IgG2, 3 and 4 levels, on the other hand, were fairly similar. 相似文献
5.
Marcela Hernández Hoyos Piotr Orłowski Ewa Piątkowska-Janko Piotr Bogorodzki Maciej Orkisz 《International journal of computer assisted radiology and surgery》2006,1(1):51-61
The accuracy of 2D phase contrast (PC) magnetic resonance angiography (MRA) depends on the alignment between the vessels and
the imaging plane. PC MRA imaging of blood flow is challenging when the flow in several vessels is to be evaluated with one
acquisition. For this purpose, semi-automatic determination of the plane most perpendicular to several vessels is proposed
based on centerlines extracted from 3D MRA. Arterial centerlines are extracted from 3D MRA based on iterative estimation-prediction,
multi-scale analysis of image moments, and a second-order shape model. The optimal plane is determined by minimizing misalignment
between its normal vector and the centerlines’ tangent vectors. The method was evaluated on a phantom and on 35 patients,
by seeking the optimal plane for cerebral blood flow quantification simultaneously in internal carotids and vertebral arteries.
In the phantom, difference of orientation and of height between known and calculated planes was 1.2° and 2.5 mm, respectively.
In the patients, all but one centerline were correctly extracted and the misalignment of the plane was within 12° per artery.
Semi-automatic centerline extraction simplifies and automates determination of the plane orthogonal to one vessel, thereby
permitting automatic simultaneous minimization of the misalignment with several vessels in PC MRA. 相似文献
6.
Dalton Pompêo de Pina M.D. 《Aesthetic plastic surgery》1990,14(1):27-33
Recently many mammaplasty techniques have been presented with special attention paid to the resulting scar's size and its position. The surgeon should try to hid the scar, and if the inverted T incision is used, its horizontal branch should be as short as possible and kept in the breast area. Neverthelss, excessive concern about the final scar size should not interfere with the final results of the mammaplasty as far as shape, volume and lasting results are concerned. The author presents his experience in mammaplasty with respect to the volume, the shape, and the scar size interrelationships. 相似文献
7.
8.
F. M. González Valverde F. Mauri Barberá M. Molto Aguado N. Torregrosa A. Hernández Quiles F. Menárguez Pina M. J. Gómez Ramos M. García Real J. A. Barreras Mateos J. L. Vázquez Rojas 《European Surgery》2004,36(4):253-256
Summary BACKGROUND: Endometriosis is a relatively common pathology in women of childbearing age and of low parity but rarely shows
extraperitoneal involvement. The main aim of this paper is to raise the attention of specialists to the necessity of carrying
out penetrating diagnosis of nonspecific extraperitoneal masses occurring in women of reproductive age. METHODS: We performed
a retrospective review of six patients diagnosed with extraperitoneal endometriosis who were treated at the Vega Baja University
Hospital (Spain) during the last 5 years. RESULTS: Surgical treatment had positive results in five patients. The preoperative
diagnosis was correctly made in only two patients. The accurate aetiology of endometriosis remains unknown and diagnosis is
based on clinical and cytopathological findings. CONCLUSIONS: Surgical treatment of extraperitoneal endometriosis is recommended.
However, postoperative follow-up is obligatory and hormonal suppressive therapy may be necessary. Medical treatment with gestagens,
Danazol, or agonists of the gonadotropin-releasing hormone are ineffective in endometriomas which are bigger than 2 cm.
相似文献
9.
Marina Quartu Maria Pina Serra Annalisa Manca Paolo Follesa Rossano Ambu Marina Del Fiacco 《International journal of developmental neuroscience》2003,21(6):309-320
The immunohistochemical occurrence of the high affinity neurotrophin (NT) receptors trkA, trkB, and trkC is shown in the pre-term newborn, infant, and adult human post-mortem cerebellum. Immunoreactive neuronal perikarya and processes were observed in all specimens examined, where they appeared unevenly distributed in the cerebellar cortical layers and deep nuclei, and showed regional differences among cerebellar lobules and folia. The trk receptor-antibodies, tested by Western blot on human cerebellum homogenates, revealed multiple immunoreactive bands for trkA and single bands for trkB and trkC. The results obtained show the tissue localization of the trk receptor-like immunoreactivity in the human cerebellum from prenatal to adult age. The analysis for codistribution of the receptors with the relevant ligand and among the receptors in discrete cortical and deep nuclei tissue fields shows a wide variety of conditions, from a good similarity in terms of type and density of labeled structures, to a lack of correspondence, and suggests the possibility of colocalization of trk receptors with the relevant neurotrophin and among them in the cerebellar cortex. These results sustain the concept that the neurotrophin trophic system participates in the development, differentiation, and maintenance of the human cerebellar connectivity and support the possibility of a multifactorial trophic support for the neurotrophins through target-derived and local mechanisms. 相似文献
10.
D.R. Pina S.B. Duarte J. Morceli T. Ghilardi Netto 《Applied radiation and isotopes》2006,64(12):1623-1630
We present the construction of a homogeneous phantom to be used in simulating the scattering and absorption of X-rays by a standard patient chest and skull when irradiated laterally. This phantom consisted of lucite and aluminium plates with their thickness determined by a tomographic exploratory method applied to the anthropomorphic phantom. Using this phantom, an optimized radiographic technique was established for chest and skull of standard sized patient in lateral view. Images generated with this optimized technique demonstrated improved image quality and reduced radiation doses. 相似文献