全文获取类型
收费全文 | 2473205篇 |
免费 | 184228篇 |
国内免费 | 5535篇 |
专业分类
耳鼻咽喉 | 35049篇 |
儿科学 | 78675篇 |
妇产科学 | 71580篇 |
基础医学 | 347658篇 |
口腔科学 | 71032篇 |
临床医学 | 216044篇 |
内科学 | 487379篇 |
皮肤病学 | 57225篇 |
神经病学 | 201049篇 |
特种医学 | 96135篇 |
外国民族医学 | 879篇 |
外科学 | 376272篇 |
综合类 | 57678篇 |
现状与发展 | 8篇 |
一般理论 | 863篇 |
预防医学 | 184373篇 |
眼科学 | 57761篇 |
药学 | 180172篇 |
5篇 | |
中国医学 | 5444篇 |
肿瘤学 | 137687篇 |
出版年
2018年 | 25300篇 |
2017年 | 19641篇 |
2016年 | 21992篇 |
2015年 | 24737篇 |
2014年 | 35042篇 |
2013年 | 52760篇 |
2012年 | 70442篇 |
2011年 | 74567篇 |
2010年 | 44132篇 |
2009年 | 42512篇 |
2008年 | 70145篇 |
2007年 | 75167篇 |
2006年 | 76152篇 |
2005年 | 73892篇 |
2004年 | 71046篇 |
2003年 | 68259篇 |
2002年 | 66710篇 |
2001年 | 119197篇 |
2000年 | 122284篇 |
1999年 | 102653篇 |
1998年 | 28458篇 |
1997年 | 25835篇 |
1996年 | 25376篇 |
1995年 | 24068篇 |
1994年 | 22178篇 |
1993年 | 20703篇 |
1992年 | 78668篇 |
1991年 | 75598篇 |
1990年 | 73424篇 |
1989年 | 70866篇 |
1988年 | 65627篇 |
1987年 | 64238篇 |
1986年 | 61104篇 |
1985年 | 57978篇 |
1984年 | 43957篇 |
1983年 | 37194篇 |
1982年 | 22557篇 |
1981年 | 20337篇 |
1979年 | 40530篇 |
1978年 | 28790篇 |
1977年 | 24577篇 |
1976年 | 22554篇 |
1975年 | 24656篇 |
1974年 | 29292篇 |
1973年 | 28518篇 |
1972年 | 27047篇 |
1971年 | 24910篇 |
1970年 | 23755篇 |
1969年 | 22529篇 |
1968年 | 21260篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A case of esthesioneuroblastoma with an unusual clinical and radiographic presentation is reported. The presenting symptoms as well as the computed tomographic examination were compatible with a primary intracranial mass. 相似文献
992.
Summary. Twenty artificial periapical lesions confined to cancellous bone were prepared at the apices of first and second mandibular molars of human cadavers. The lesions emphasized removal of the lamina dura and preparation of a 'halo' lesion surrounding the root apex, plus the addition of a simulated sclerotic border. Radiographs taken before and after creation of the lesions were scored by three examiners for detectable lesions Cross-sections of the lesions were assessed for the extent of bone destruction. Periapical lesions confined to cancellous bone were detected in 80 per cent of cases, and the presence of a sclerotic border tended to enhance visualization, although not in all cases. Intentional cortical involvement also improved detection of lesions. The anatomical features of the periapical area appear to promote the visualization of lesions which might not be detected in other locations. 相似文献
993.
The effect of chronic inflammation on gingival connective tissue proteoglycans and hyaluronic acid 总被引:1,自引:0,他引:1
Proteoglycans have been isolated and analysed from extracts of normal and chronically inflamed human gingiva in order to determine the effects of chronic inflammation on these important soft connective tissue extracellular macromolecules. The uronic acid content of glycosaminoglycans isolated by papain digestion of normal and inflamed gingiva did not differ significantly. Likewise, electrophoretic analysis revealed that the content of hyaluronic acid, heparan sulfate, dermatan sulfate and chondroitin sulfute was similar. The sulfated glycosaminoglycans from both sources eluted from a Sepharose C1-6B column with a Kav of 0.45 (approximate Mr 25,000). However, hyaluronic acid from normal gingiva was predominantly of a large size eluting in the void volume of a Sepharose. CL-6B column, while that isolated from inflamed tissue was mostly a small molecular weight species which elutccl in the included volume of a Sepharose CL-6B column. Using dissociative conditions, intact proteoglycans could be more readily extracted from inflamed tissues (90% of the total tissue uronic acid) than from normal tissues where only 80% of the total tissue uronic acid was extractable. Even though DEAE-Sephacel ion-exchange chromatography revealed no differences in charge between normal and inflamed gingival proteoglycans, Sepharose CL-4B chromatography revealed more molecular size polydispersity in samples from inflamed tissue than from normal tissue. Taken together, these results indicate that while hyaluronic acid is depolymerized in inflamed tissue, no evidence of sulfated glycosaminoglycan degradation was found. Therefore, the most likely cause for disruption to the molecular integrity of the proteoglycans is via proteolytic alteration to the proteoglycan core protein. 相似文献
994.
The thesis of this article is that deficits in language and communication contribute to behavior problems in childhood. Mentally retarded children show a range of deficits in language and communication compared with normals; they are also at increased risk for behavior problems. The evidence suggests that these deficits are quantitative rather than qualitative. In addition, these linguistic deficits may contribute independently to the development of behavior disorders insofar as the linguistic deficit interferes with the child's ability to make himself understood or to understand others. 相似文献
995.
Magnetic resonance imaging in planning limb-salvage surgery for primary malignant tumors of bone 总被引:4,自引:0,他引:4
M Sundaram M H McGuire D R Herbold M K Wolverson E Heiberg 《The Journal of bone and joint surgery. American volume》1986,68(6):809-819
In defining the linear extent of a malignant tumor in a long bone, radiographs, computerized tomography, and scintigraphy are routinely employed, especially when non-ablative surgery is being considered. The drawbacks of these modalities in defining the true intracompartmental extent of disease within a bone can largely be overcome with the use of magnetic resonance imaging. We did a prospective analysis of magnetic resonance imaging in sixteen consecutive patients with a primary malignant tumor of a long bone, and it showed that this modality has clinical promise of being more precise than the other modalities in defining the true proximal and distal extent of a tumor in a long bone. Coronal images permit easier planning of surgical techniques for salvage of a limb using an allograft than do a multiplicity of transverse images. 相似文献
996.
997.
998.
M Herbst H Fritz H G Nüsslein B J Manger J R Kalden R Sauer 《Strahlentherapie und Onkologie》1986,162(1):25-30
Eleven patients with refractory rheumatoid arthritis were submitted to a total lymphoid irradiation up to a dose of 20 Gy. A constant improvement of clinical symptoms was observed in four out of the eleven patients already during the treatment and in the other patients not later than two months after. The frequency of attacks decreased and the number of joints involved in the attack was reduced. Morning rigidity and joint swellings decreased. One patient developed joint empyemas 4 and 26 months after the treatment. Four patients died in the meantime. In two patients the cause of death were renal insufficiency and a postoperative cardiogenic shock associated with generalized amyloidosis. The third patient died because of a toxically induced left cardiac decompensation with sepsis that could not be controlled by antibiotic drugs and multiple joint empyemas. The fourth patient developed an abscess after surgical treatment of a Kaposi syndrome. She died three months later from acute left cardiac decompensation. The therapy induced a lymphocytopenia with decrease of T helper lymphocytes and unchanged number of T suppressor lymphocytes. The constant therapy results of total lymphoid irradiation in primary chronic polyarthritis is probably due to this modification in the immune regulation. 相似文献
999.
E D Endean S K Mukhopadhyay L K Fung J L Cronenwett J C Stanley S M Lindenauer 《The Journal of surgical research》1986,40(1):49-54
Basal isolated canine paw blood flow was equally distributed between arteriovenous anastomosis (AVA) and capillary circulations. Norepinephrine decreased AVA flow by 92% and capillary flow by 41%. Dopamine significantly reduced AVA flow by 94% compared to baseline with a 37% reduction in capillary flow. However, with alpha-adrenergic blockade dopamine decreased AVA flow 66% while capillary flow increased 42%. Isoproterenol increased capillary flow almost twofold and appeared to decrease AVA flow, although the latter was statistically insignificant. Differential effects of adrenergic and dopaminergic agonists on canine paw AVA and capillary blood flow suggest the existence of independent regulation of these components of the microcirculation. 相似文献
1000.
Mitogen responsiveness of lymphocytes from the BB/W rat 总被引:3,自引:0,他引:3
The response of BB diabetes-prone (DP) and W-line non-diabetes-prone rats to the T-cell mitogen concanavalin A (ConA) was measured. The W line was a good responder to ConA, whereas the DP was relatively unresponsive. This unresponsiveness could not be reversed with exogenous interleukin 2 (IL-2). The response of DP rats was enhanced by removing adherent cells. To directly test the response of BB T-cells, they were isolated by flow sorting. These experiments demonstrated that BB T-cells could mount a normal ConA response. The normal function of isolated BB T-cells suggested that they were under suppression. Suppressor activity could not be found in the OX8+ population but was found in the DP-adherent cell population. Adherent cells from the W line were not suppressive at the concentrations used. These results showed that the decreased mitogen responsiveness of BB T-cells was not due to an intrinsic T-cell abnormality but was due, in part, to suppression by adherent cells. 相似文献