全文获取类型
收费全文 | 172388篇 |
免费 | 11827篇 |
国内免费 | 550篇 |
专业分类
耳鼻咽喉 | 2652篇 |
儿科学 | 4948篇 |
妇产科学 | 5117篇 |
基础医学 | 20902篇 |
口腔科学 | 5655篇 |
临床医学 | 24629篇 |
内科学 | 39650篇 |
皮肤病学 | 5006篇 |
神经病学 | 13018篇 |
特种医学 | 3652篇 |
外国民族医学 | 2篇 |
外科学 | 19660篇 |
综合类 | 994篇 |
一般理论 | 43篇 |
预防医学 | 16738篇 |
眼科学 | 3361篇 |
药学 | 10931篇 |
中国医学 | 872篇 |
肿瘤学 | 6935篇 |
出版年
2023年 | 1672篇 |
2022年 | 1692篇 |
2021年 | 4352篇 |
2020年 | 2628篇 |
2019年 | 4118篇 |
2018年 | 6674篇 |
2017年 | 4629篇 |
2016年 | 4538篇 |
2015年 | 5002篇 |
2014年 | 6242篇 |
2013年 | 8569篇 |
2012年 | 11195篇 |
2011年 | 12288篇 |
2010年 | 7127篇 |
2009年 | 6038篇 |
2008年 | 9580篇 |
2007年 | 10010篇 |
2006年 | 9316篇 |
2005年 | 9180篇 |
2004年 | 8214篇 |
2003年 | 7611篇 |
2002年 | 7030篇 |
2001年 | 4846篇 |
2000年 | 5228篇 |
1999年 | 4285篇 |
1998年 | 1399篇 |
1997年 | 1320篇 |
1996年 | 1162篇 |
1995年 | 1023篇 |
1994年 | 777篇 |
1993年 | 630篇 |
1992年 | 1737篇 |
1991年 | 1474篇 |
1990年 | 1356篇 |
1989年 | 1101篇 |
1988年 | 936篇 |
1987年 | 865篇 |
1986年 | 865篇 |
1985年 | 779篇 |
1984年 | 556篇 |
1983年 | 480篇 |
1979年 | 502篇 |
1978年 | 346篇 |
1975年 | 335篇 |
1974年 | 413篇 |
1973年 | 413篇 |
1972年 | 410篇 |
1971年 | 361篇 |
1970年 | 326篇 |
1969年 | 347篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Lethal encephalitis in myeloid differentiation factor 88-deficient mice infected with herpes simplex virus 1
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mansur DS Kroon EG Nogueira ML Arantes RM Rodrigues SC Akira S Gazzinelli RT Campos MA 《The American journal of pathology》2005,166(5):1419-1426
Herpes simplex virus 1 (HSV-1), a large DNA virus from the Herpesviridae family, is the major cause of sporadic lethal encephalitis and blindness in humans. Recent studies have shown the importance of Toll-like receptors (TLRs) in the immune response to HSV-1 infection. Myeloid differentiation factor 88 (MyD88) is a critical adaptor protein that is downstream to mediated TLR activation and is essential for the production of inflammatory cytokines. Here, we studied the relationship between MyD88 and HSV-1 using a purified HSV-1 isolated from a natural oral recurrent human infection. We observed the activation of TLR-2 by HSV-1 in vitro using Chinese hamster ovary cells stably transfected with a reporter gene. Interestingly, we found that only peritoneal macrophages from MyD88-/- mice, but not macrophages from TRL2-/- or from wild-type mice, were unable to produce tumor necrosis factor-alpha in response to HSV-1 exposure. Additionally, although TLR2-/- mice showed no enhanced susceptibility to intranasal infection with HSV-1, MyD88-/- mice were highly susceptible to infection and displayed viral migration to the brain, severe neuropathological signs of encephalitis, and 100% mortality by day 10 after infection. Together, our results suggest that innate resistance to HSV-1 is mediated by MyD88 and may rely on activation of multiple TLRs. 相似文献
992.
In this paper, the specific absorption rate (SAR) in scaled human head models is analysed to study possible differences between SAR in the heads of adults and children and for assessment of compliance with the international safety guidelines, while using a mobile phone. The finite-difference time-domain method (FDTD) has been used for calculating SAR values for models of both children and adults, at 900 and 1800 MHz. Maximum 1 g averaged SAR (SAR1 g) and maximum 10 g averaged SAR (SAR10 g) have been calculated in adults and scaled head models for comparison and assessment of compliance with ANSI/IEEE and European guidelines. Results show that peak SAR1 g and peak SAR10 g all trend downwards with decreasing head size but as head size decreases, the percentage of energy absorbed in the brain increases. So, higher SAR in children's brains can be expected depending on whether the thickness of their skulls and surrounding tissues actually depends on age. The SAR in eyes of different sizes, as a critical organ, has also been studied and very similar distributions for the full size and the scaled models have been obtained. Standard limits can only be exceeded in the unpractical situation where the antenna is located at a very short distance in front of the eye. 相似文献
993.
Early-onset gastric carcinomas display molecular characteristics distinct from gastric carcinomas occurring at a later age 总被引:5,自引:0,他引:5
Carvalho R Milne AN van Rees BP Caspers E Cirnes L Figueiredo C Offerhaus GJ Weterman MA 《The Journal of pathology》2004,204(1):75-83
Gastric cancer is thought to result from a combination of environmental factors and accumulation of specific genetic alterations, and consequently mainly affects older patients (>50 years of age). Fewer than 10% of patients present with the disease before 45 years of age and these young patients are thought to develop carcinomas with a different molecular genetic profile from that of sporadic carcinomas occurring at a later age. Forty early-onset gastric carcinoma resection specimens were characterized for microsatellite instability (MSI) and loss of heterozygosity status using 22 polymorphic microsatellite markers. Twenty-four biopsies were additionally evaluated for the presence of MSI. No MSI was observed in any of the cases analysed. Losses were infrequent, but were most common for the D1S234 (26.1%) and D1S1676 (17.4%) markers, flanking the RUNX3 gene; for the p53ALU (23.1%) and TP53 (15.4%) markers, near the TP53 gene; and for the D16S2624 (17.2%) marker, near the E-cadherin (CDH1) gene. All cases with loss of CDH1, as well as 6/7 cases with loss of TP53, displayed aberrant staining of the corresponding proteins, pointing to a functional role for these proteins in early-onset gastric carcinogenesis. No germline CDH1, TP53 or RUNX3 mutations were detected in any of the cases analysed. No correlation was observed between non-functional E-cadherin and the histological type of the tumours analysed. Finally, Epstein-Barr virus was not detected in any of the cases analysed. On the basis of these results, early-onset gastric carcinomas appear to have characteristics distinct from gastric carcinomas occurring at a later age. 相似文献
994.
Carreiro-Rodríguez M Hernández-Blanca D Fernández LM Montes de Oca I Castillo E Sánchez JL 《Investigación clínica》1999,40(4):267-276
We describe a case of hypertrophic pulmonary osteoarthropathy (HPOA) in an adult patient with acquired immunodeficiency syndrome (AIDS). This is the ninth case of HPOA associated with AIDS in adults, reported in the literature. The presence of pulmonary tuberculosis was also suspected, based on clinical grounds. Cases of clubbing associated with AIDS infection are reviewed. 相似文献
995.
C. Castro R. Martín T. García E. Rodríguez I. González B. Sanz 《Food and Agricultural Immunology》1992,4(1):11-18
An indirect enzyme‐linked immunosorbent assay (ELISA) has been developed for the specific detection of cow's milk (1–25%) in goat's milk. The test uses polyclonal antibodies raised in rabbits against bovine whey proteins (BWP). The anti‐BWP antibodies were recovered from the crude antiserum by immunoadsorption and elution from a column containing immobilized BWP. The anti‐BWP antibodies were biotinylated and rendered cow's milk specific by mixing them with lyophilized ovine and caprine whey proteins. Streptavidin‐peroxidase was used to detect the biotinylated anti‐BWP antibodies bound to bovine milk proteins immobilized on 96‐well plates. The colour developed by the subsequent enzymic conversion of the substrate gave clear absorbance differences when assaying mixtures of goat's milk containing variable amounts of cow's milk. 相似文献
996.
Cristina Benito Eloína González-Mancebo M Dolores Alonso Díaz de Durana Rosa M Tolón Montserrat Fernández-Rivas 《Annals of allergy, asthma & immunology》2007,98(6):580-584
BACKGROUND: Coconut (Cocos nucifera) is a monocotyledonous plant of the Arecaceae family. Allergy to coconut is infrequent, with only 5 cases reported so far in the medical literature. OBJECTIVE: To identify coconut allergens in 2 patients allergic to this food. METHODS: We describe 2 patients allergic to coconut: an adult pollen-allergic patient monosensitized to coconut who presented with severe oropharyngeal symptoms and a child with a previous allergy to walnut, not allergic to pollen, who developed anaphylaxis on coconut ingestion. Both patients had positive skin prick test results and serum specific IgE (CAP) to coconut. IgE sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblotting was performed to identify the allergens involved, and a strong IgE binding band detected in both patients was further analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS). Stability to pepsin digestion of the coconut extract and its cross-reactivity with tree nuts were studied. RESULTS: An immunoblot showed an almost identical profile of IgE binding proteins in the coconut extract in both patients who reacted strongly to a band of approximately 29 kDa. The peptide analysis by MALDI-TOF MS of this band obtained the sequence GHGKREDPEKR. The protein with the highest correlation with this peptide was found to be a 7S globulin from Elaeis guineensis, another oil palm species also belonging to the Arecaceae family. The 29-kDa band was digested by pepsin in less than 1 minute. Cross-reactivity among coconut, walnut, and hazelnut was demonstrated by CAP inhibition in patient 2. CONCLUSION: We have identified a 7S storage protein as a novel coconut allergen. 相似文献
997.
Concepción Núñez Diana Alecsandru Jezabel Varadé Isabel Polanco Carlos Maluenda Miguel Fernández-Arquero Emilio G de la Concha Elena Urcelay Alfonso Martínez 《BMC medical genetics》2006,7(1):32-5
Background
Celiac disease (CD) is a chronic disorder characterized by a pathological inflammatory response after exposure to gluten in genetically susceptible individuals. The HLA complex accounts for less than half of the genetic component of the disease, and additional genes must be implicated. Interleukin-10 (IL-10) is an important regulator of mucosal immunity, and several reports have described alterations of IL-10 levels in celiac patients. The IL-10 gene is located on chromosome 1, and its promoter carries several single nucleotide polymorphisms (SNPs) and microsatellites which have been associated to production levels. Our aim was to study the role of those polymorphisms in susceptibility to CD in our population. 相似文献998.
999.
Enteropathogenic Escherichia coli strains carrying genes encoding the PER-2 and TEM-116 extended-spectrum beta-lactamases isolated from children with diarrhea in Uruguay 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Vignoli R Varela G Mota MI Cordeiro NF Power P Ingold E Gadea P Sirok A Schelotto F Ayala JA Gutkind G 《Journal of clinical microbiology》2005,43(6):2940-2943
We studied 13 extended-spectrum beta-lactamase (ESBL)-producing enteropathogenic Escherichia coli isolates from children suffering acute diarrhea in Uruguay. ESBL characterization in crude extracts showed a single band at pI 5.4. PCR amplification and sequencing data allowed identification of blaPER-2 and blaTEM-116. Retrospective analysis suggests that these strains were disseminated in the community, even if unnoticed, prior to their access to the hospital environment more than a decade ago. 相似文献
1000.
Fecal specimens were obtained from 3- to 8-month-old post-weaned dairy calves on farms in Vermont, New York, Pennsylvania, Maryland, Virginia, North Carolina, and Florida. After removal of fecal debris by sieving and density gradient centrifugation, 59 of 452 calves (13%) from 11 farms in six states were found positive for Enterocytozoon bieneusi by PCR and DNA sequence analysis. Based on gene sequence data this genotype of E. bieneusi found in post-weaned calves was 100% identical to that found in pre-weaned calves in North America and differed by only two positions in 1,069 base pairs from specimens analyzed from humans. However, compared with previous reports, the prevalence of E. bieneusi was significantly higher in post-weaned than in pre-weaned calves from many of the same farms. 相似文献