全文获取类型
收费全文 | 10411篇 |
免费 | 957篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 132篇 |
儿科学 | 379篇 |
妇产科学 | 234篇 |
基础医学 | 1557篇 |
口腔科学 | 280篇 |
临床医学 | 1330篇 |
内科学 | 2139篇 |
皮肤病学 | 166篇 |
神经病学 | 1259篇 |
特种医学 | 285篇 |
外科学 | 1207篇 |
综合类 | 185篇 |
一般理论 | 19篇 |
预防医学 | 766篇 |
眼科学 | 160篇 |
药学 | 632篇 |
中国医学 | 8篇 |
肿瘤学 | 657篇 |
出版年
2022年 | 98篇 |
2021年 | 223篇 |
2020年 | 132篇 |
2019年 | 197篇 |
2018年 | 209篇 |
2017年 | 203篇 |
2016年 | 222篇 |
2015年 | 274篇 |
2014年 | 330篇 |
2013年 | 424篇 |
2012年 | 666篇 |
2011年 | 601篇 |
2010年 | 378篇 |
2009年 | 336篇 |
2008年 | 518篇 |
2007年 | 539篇 |
2006年 | 562篇 |
2005年 | 495篇 |
2004年 | 436篇 |
2003年 | 411篇 |
2002年 | 331篇 |
2001年 | 229篇 |
2000年 | 230篇 |
1999年 | 227篇 |
1998年 | 143篇 |
1997年 | 107篇 |
1996年 | 68篇 |
1995年 | 65篇 |
1994年 | 63篇 |
1993年 | 63篇 |
1992年 | 165篇 |
1991年 | 167篇 |
1990年 | 167篇 |
1989年 | 170篇 |
1988年 | 146篇 |
1987年 | 172篇 |
1986年 | 150篇 |
1985年 | 125篇 |
1984年 | 115篇 |
1983年 | 98篇 |
1982年 | 57篇 |
1981年 | 62篇 |
1980年 | 67篇 |
1979年 | 114篇 |
1978年 | 79篇 |
1977年 | 59篇 |
1975年 | 68篇 |
1974年 | 72篇 |
1973年 | 67篇 |
1972年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Matthias Niedrig Katrin Leitmeyer Wilina Lim Malik Peiris John S Mackenzie Maria Zambon 《Journal of clinical virology》2005,34(1):22-25
To confirm an infection with the new coronavirus (SARS-CoV) causing the severe acute respiratory syndrome (SARS) diagnostic assays for detection of SARS-CoV specific antibody are necessary. To evaluate the diagnostic performance of laboratories an external quality assurance (EQA) study was performed in 2004. Participating laboratories (9/20) correctly detected anti-SARS antibodies in serum samples without false positive results in an immunofluorescence assay. In contrast, only 4/13 laboratories detected most of the anti-SARS antibody positive samples without false positive results using enzyme immunoassays (EIA) and/or immunoblot. The overall results clearly demonstrate that serological diagnosis of SARS-CoV remains at an early stage of development, with further technical improvements required, particularly with respect to the use of SARS specific EIAs. 相似文献
93.
Hubert Sch?fer Katrin Klippert Petra Meuer Bettina Borsdorf Albrecht F Kiderlen Reinhard Burger 《Journal of interferon & cytokine research》2007,27(4):305-315
Interferon-gamma (IFN-gamma) plays a key role in the induction and maintenance of immunity against intracellular infectious agents. Compared to other species, little is known about the biology of this cytokine in the guinea pig (Cavia porcellus). We found that in contrast to humans and mice, IFN-gamma in the guinea pig did not induce the antiviral state, which in other species leads to protection of IFN-gamma -stimulated fibroblasts from the cytopathic effect (CPE) of subsequent viral infections. As an alternative strategy to detect and quantify guinea pig IFN-gamma activity in vitro, a reporter system using guinea pig fibroblasts transfected with a luciferase gene, which is regulated by an IFN-stimulated response element (ISRE), was established. With the help of the highly sensitive reporter assay system, the biologic activity of recombinant guinea pig IFN-gamma (GpIFN-gamma, from prokaryotic and eukaryotic expression systems was detected. The response to both native and recombinant GpIFN-gamma was inhibited by a rabbit antiserum directed against the recombinant cytokine expressed in Escherichia coli, demonstrating structural and functional homology of native and recombinant GpIFN-gamma. Stimulation with GpIFN-gamma, obtained from transfected cells, induced upregulation of MHC class I expression in a guinea pig fibroblast line. The restricted activity of GpIFN-gamma might have implications for this species' ability to control infections with intracellular pathogens. 相似文献
94.
Stroke following coronary-artery bypass surgery. A case-control estimate of the risk from carotid bruits 总被引:4,自引:0,他引:4
G L Reed D E Singer E H Picard R W DeSanctis 《The New England journal of medicine》1988,319(19):1246-1250
The causes of stroke following coronary-artery bypass surgery are largely unknown. To determine whether carotid bruits increase the risk of these events, we compared 54 patients with postoperative stroke or transient ischemic attacks with 54 randomly selected control patients. Both groups were drawn from 5915 consecutive patients who had coronary bypass surgery at our hospital from 1970 to 1984. Carotid bruits were noted preoperatively in 13 patients with postoperative stroke and in 4 control patients. Case-control analysis showed that the presence of carotid bruits increased the risk of stroke or transient ischemic attacks by 3.9-fold (95 percent confidence interval, 1.2 to 12.8; P less than 0.05). This increased risk remained essentially unchanged after adjustment for potentially confounding variables in a multiple logistic regression analysis. Other factors associated with a significantly increased risk (P less than 0.05) of these neurologic deficits were a history of stroke or transient ischemic attack (odds ratio, 6.0; 95 percent confidence interval, 1.6 to 22.1), a history of congestive heart failure (odds ratio, 5.3; confidence interval, 1.6 to 17.0), mitral regurgitation (odds ratio, 4.3; confidence interval, 1.4 to 12.9), postoperative atrial fibrillation (odds ratio, 3.0; confidence interval, 1.4 to 6.7), a cardiopulmonary-bypass pump time of more than two hours (odds ratio, 2.7; confidence interval, 1.1 to 6.7), and a previous myocardial infarction (odds ratio, 2.3; confidence interval, 1.1 to 5.1). We conclude that the presence of carotid bruits increases the risk of stroke after coronary-artery bypass surgery. However, the absolute magnitude of this risk, 2.9 percent, is small and comparable to the reported risk of stroke from carotid endarterectomy. 相似文献
95.
96.
Warncke B Valtink M Weichel J Engelmann K Schäfer H 《Virchows Archiv : an international journal of pathology》2004,444(1):74-81
Transplantation of retinal pigment epithelial (RPE) cells is discussed as a possible therapeutic approach for retinal degeneration. Xenogeneic transplantation of human RPE cells in animal models has been studied extensively. Various methods have been used to identify the graft cells, but these methods interfere with cell behaviour so that the monitored physiological post-transplantation course may be influenced. In the present study, we applied a method for an unequivocal identification of the graft cells without interfering cell metabolism or behaviour using in situ hybridisation (ISH) of human specific Alu sequences. Visualisation of the strong extended nuclear signal of Alu sequences was much easier than that of the small nuclear signals of donor-specific sex chromosome probes. With Alu probe, even single graft cells can be identified and their development can be observed in short-term and long-term studies. With this procedure, we could prove that donor cells were injected correctly into the subretinal space by a special injection technique that we developed previously. In combination with immunohistochemistry, donor cells could be clearly discriminated from macrophages, which contained phagocytosed donor cell fragments. Application of these ISH methods for species-specific identification was valuable for follow-up-studies of RPE transplantation. 相似文献
97.
98.
The antigen-presenting environment in normal and human papillomavirus (HPV)-related premalignant cervical epithelium 总被引:13,自引:0,他引:13
The activation of HPV-specific T cells within the cervical microenvironment is likely to play an important part in the natural history of cervical intraepithelial neoplasia (CIN). The extent and the type of T cell activation will depend critically on the expression of MHC, costimulatory cell surface molecules and cytokines by keratinocytes and Langerhans cells within the cervical lesion. Expression of MHC class II (HLA-A-DR and -DQ), costimulatory/adhesion molecules (CD11a/18, CD50, CD54, CD58 and CD86) and cytokines (tumour necrosis factor-alpha (TNF-alpha) and IL-10) was therefore investigated by immunohistochemistry in normal squamous epithelium (n = 12), low-grade (n = 23) and high-grade (n = 18) squamous intraepithelial lesions of the cervix. CIN progression was associated with de novo expression of HLA-DR and CD54, and increased expression of CD58 by keratinocytes. However, significantly, there was no expression of any adhesion/costimulation molecule by epithelial Langerhans cells in any cervical biopsy studied. Furthermore, TNF-alpha, a potent activator of Langerhans cells, was expressed constitutively by basal keratinocytes in normal cervix (12+/12). but expression of this cytokine was absent in a number of CIN samples (20+/23 for low-grade, 12+/18 for high-grade CIN). Conversely, the suppressive cytokine IL-10 was absent in normal epithelium (0+/12), but was up-regulated in a number of CIN lesions (12+/23 for low-grade; 8+/18 for high-grade CIN). The restricted expression of costimulation/adhesion molecules and the nature of the cytokine microenvironment within the epithelium may act to limit effective immune responses in some CIN lesions. 相似文献
99.
Will Katrin; Stuhrmann Manfred; Dean Michael; Schmidtke Jorg 《Human molecular genetics》1993,2(3):231-235