全文获取类型
收费全文 | 15022篇 |
免费 | 899篇 |
国内免费 | 101篇 |
专业分类
耳鼻咽喉 | 159篇 |
儿科学 | 489篇 |
妇产科学 | 516篇 |
基础医学 | 1804篇 |
口腔科学 | 370篇 |
临床医学 | 1436篇 |
内科学 | 3300篇 |
皮肤病学 | 339篇 |
神经病学 | 771篇 |
特种医学 | 434篇 |
外国民族医学 | 3篇 |
外科学 | 1954篇 |
综合类 | 358篇 |
一般理论 | 11篇 |
预防医学 | 1241篇 |
眼科学 | 496篇 |
药学 | 1300篇 |
中国医学 | 109篇 |
肿瘤学 | 932篇 |
出版年
2023年 | 201篇 |
2022年 | 446篇 |
2021年 | 664篇 |
2020年 | 436篇 |
2019年 | 554篇 |
2018年 | 645篇 |
2017年 | 475篇 |
2016年 | 461篇 |
2015年 | 416篇 |
2014年 | 658篇 |
2013年 | 847篇 |
2012年 | 1185篇 |
2011年 | 1202篇 |
2010年 | 653篇 |
2009年 | 499篇 |
2008年 | 861篇 |
2007年 | 917篇 |
2006年 | 737篇 |
2005年 | 740篇 |
2004年 | 607篇 |
2003年 | 515篇 |
2002年 | 447篇 |
2001年 | 173篇 |
2000年 | 145篇 |
1999年 | 154篇 |
1998年 | 83篇 |
1997年 | 66篇 |
1996年 | 62篇 |
1995年 | 60篇 |
1994年 | 59篇 |
1993年 | 46篇 |
1992年 | 76篇 |
1991年 | 70篇 |
1990年 | 85篇 |
1989年 | 74篇 |
1988年 | 71篇 |
1987年 | 66篇 |
1986年 | 66篇 |
1985年 | 55篇 |
1984年 | 43篇 |
1983年 | 28篇 |
1982年 | 29篇 |
1981年 | 18篇 |
1980年 | 31篇 |
1979年 | 32篇 |
1977年 | 28篇 |
1976年 | 27篇 |
1974年 | 17篇 |
1973年 | 18篇 |
1970年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Schild LJ Phillips DH Osborne MR Hewer A Beland FA Churchwell MI Brown K Gaskell M Wright E Poirier MC 《Mutagenesis》2005,20(2):115-124
Liver homogenates from rats fed tamoxifen (TAM) in the diet were shared among four different laboratories. TAM-DNA adducts were assayed by high pressure liquid chromatography-electrospray tandem mass spectrometry (HPLC-ES-MS/MS), TAM-DNA chemiluminescence immunoassay (TAM-DNA CIA), and (32)P-postlabeling with either thin layer ((32)P-P-TLC) or liquid chromatography ((32)P-P-HPLC) separation. In the first study, rats were fed a diet containing 500 p.p.m. TAM for 2 months, and the values for measurements of the (E)-alpha-(deoxyguanosin-N(2)-yl)-tamoxifen (dG-N(2)-TAM) adduct in replicate rat livers varied by 3.5-fold when quantified using 'in house' TAM-DNA standards, or other approaches where appropriate. In the second study, rats were fed 0, 50, 250 or 500 p.p.m. TAM for 2 months, and TAM-DNA values were quantified using both 'in house' approaches as well as a newly synthesized [N-methyl-(3)H]TAM-DNA standard that was shared among all the participating groups. In the second study, the total TAM-DNA adduct values varied by 2-fold, while values for the dG-N(2)-TAM varied by 2.5-fold. Ratios of dG-N(2)-TAM:(E)-alpha-(deoxyguanosin-N(2)-yl)-N-desmethyltamoxifen (dG-N(2)-N-desmethyl-TAM) in the second study were approximately 1:1 over the range of doses examined. The study demonstrated a remarkably good agreement for TAM-DNA adduct measurements among the diverse methods employed. 相似文献
62.
63.
Sir, From Dr Check's Letter to the Editor (2004) the main questionis whether sperm chromatin structural assay (SCSA) can be usedas a prognostic tool in assisted reproduction technologies (ART)or not. From my point of view the research on this topic isstill in its early phase, in which typical problems such assmall study groups and 相似文献
64.
65.
Rett syndrome (RTT) is classically defined by meeting certain clinical diagnostic criteria. It affects mostly females, and one possible pathogenic mechanism was considered to involve mitochondrial function. This was based on the finding of ultrastructural alterations in the mitochondria and decreased respiratory chain enzyme activity. However, the principal etiology of RTT has since been found to be mutations in the MECP2 gene, which is located on the X chromosome. Molecular analysis has allowed the phenotype of MECP2 mutations to be broadened beyond RTT to include girls who have mild mental retardation, autism, and an Angelman syndrome phenotype, as well as males with severe encephalopathy. We present a girl with a previously described mutation in the MECP2 gene whose phenotype is of atypical RTT. She presented with hypotonia and developmental delay in infancy without a clear period of normal development. As part of her evaluation for hypotonia, a muscle biopsy and respiratory chain enzyme analysis showed a slight decrease in respiratory chain enzyme activity consistent with previous reports. This report supports broadening the phenotype of patients who should be considered for MECP2 mutation analysis to include cases of developmental delay and hypotonia without evidence of an initial period of normal development. Furthermore, it supports the hypothesis of an underlying secondary defect in energy metabolism contributing to the pathogenesis of RTT. 相似文献
66.
Background
Few empirical studies have been found that explore ethical challenges among persons in high public positions that are responsible for elder care. The aim of this paper was to illuminate the meaning of being in ethically difficult situations related to elder care as experienced by high level decision-makers. 相似文献67.
Letizia Penolazzi Ilaria Lampronti Monica Borgatti Mahmud Tareq Hassan Khan Margherita Zennaro Roberta Piva Roberto Gambari 《BMC complementary and alternative medicine》2008,8(1):59
Background
Osteoclasts (OCs) are involved in rheumatoid arthritis and in several pathologies associated with bone loss. Recent results support the concept that some medicinal plants and derived natural products are of great interest for developing therapeutic strategies against bone disorders, including rheumatoid arthritis and osteoporosis. In this study we determined whether extracts of Emblica officinalis fruits display activity of possible interest for the treatment of rheumatoid arthritis and osteoporosis by activating programmed cell death of human primary osteoclasts. 相似文献68.
The immunological consequences of gold therapy: a prospective study in patients with rheumatoid arthritis. 总被引:1,自引:1,他引:1 下载免费PDF全文
J Hassan J Hanly B Bresnihan C Feighery C A Whelan 《Clinical and experimental immunology》1986,63(3):614-620
Gold sodium thiomalate (GST) is known to modify the disease process in patients with active rheumatoid arthritis (RA). To help understand the mechanism of action of GST, several immunological parameters were prospectively evaluated in 10 patients with active RA following the introduction of gold therapy. Before therapy, absolute numbers of peripheral blood T suppressor/cytotoxic lymphocytes were significantly depressed (P less than 0.01) and a raised T helper/T suppressor cell ratio was found. After 1 g of GST, an absolute reduction in total lymphocyte numbers including HLA/DR positive mononuclear cells, was evident (P less than 0.01). This lymphopenic effect was not selective for a single population since the proportions of T cells, T cell subsets and B cells remained unchanged. Lymphocyte function was also examined. Raised in vitro production of IgG (P less than 0.01) and IgA (P less than 0.05) was found before therapy. After GST, in vitro immunoglobulin synthesis was reduced and this was significant with respect to the IgM (P less than 0.001) and IgA (P less than 0.01) isotypes. Similarly, a parallel reduction in serum immunoglobulin levels developed. GST therapy was also associated with a reduced proliferative response to phytohaemagglutinin, concanavalin A and pokeweed mitogen in the initial phase of gold administration. The significant finding in this study suggest that the in vivo immunosuppressive effect of GST is explained not only by impaired mononuclear cell function but also by a significant reduction in T and B lymphocyte numbers. 相似文献
69.
Fiona Reid Jaythoon Hassan Fiona Irwin Allison Waters William Hall Jeff Connell 《Journal of clinical virology》2008,41(2):134-137
OBJECTIVE: To determine the optimal strategy to investigate mumps virus infection in a partially vaccinated cohort. STUDY DESIGN: 122 oral fluid and serum samples were collected in a recent outbreak in Ireland. The largest age cohort, students aged 18-21 years old attending third level institutions, were investigated using virus isolation, detection of mumps specific IgM, IgG, RT-PCR and molecular genotyping. RESULTS: 97% of patients had both detectable serum IgM and IgG. Mumps virus RNA was detected in 17 oral fluid samples and 14 of these originated from a single geographic location. Only 6 of the IgM positive samples had detectable mumps virus RNA whereas this could be detected in 11 IgM negative samples. Genotyping studies revealed that genotypes G and J were co-circulating during this outbreak. CONCLUSIONS: The use of an oral fluid sample to detect mumps virus RNA and IgM offers a major improvement over serological diagnosis in acute infection in both non-vaccinated or partially vaccinated individuals, and has the advantage that specimens are collected non-invasively. 相似文献
70.
Core biopsies of the bone marrow are indispensable in the evaluation of fever of unknown etiology in human immunodeficiency virus-positive patients. We report two patients in whom visceral leishmaniasis was diagnosed based on the typical morphology, staining characteristics, and ultrastructure of the organisms. 相似文献