全文获取类型
收费全文 | 14266篇 |
免费 | 1441篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 269篇 |
儿科学 | 453篇 |
妇产科学 | 338篇 |
基础医学 | 1878篇 |
口腔科学 | 351篇 |
临床医学 | 1710篇 |
内科学 | 3040篇 |
皮肤病学 | 220篇 |
神经病学 | 1158篇 |
特种医学 | 405篇 |
外科学 | 2020篇 |
综合类 | 365篇 |
一般理论 | 14篇 |
预防医学 | 1494篇 |
眼科学 | 284篇 |
药学 | 1038篇 |
中国医学 | 7篇 |
肿瘤学 | 695篇 |
出版年
2022年 | 118篇 |
2021年 | 209篇 |
2020年 | 156篇 |
2019年 | 230篇 |
2018年 | 241篇 |
2017年 | 211篇 |
2016年 | 191篇 |
2015年 | 265篇 |
2014年 | 319篇 |
2013年 | 464篇 |
2012年 | 703篇 |
2011年 | 691篇 |
2010年 | 372篇 |
2009年 | 366篇 |
2008年 | 601篇 |
2007年 | 664篇 |
2006年 | 628篇 |
2005年 | 631篇 |
2004年 | 600篇 |
2003年 | 631篇 |
2002年 | 543篇 |
2001年 | 406篇 |
2000年 | 482篇 |
1999年 | 366篇 |
1998年 | 173篇 |
1997年 | 138篇 |
1996年 | 142篇 |
1995年 | 128篇 |
1994年 | 113篇 |
1993年 | 109篇 |
1992年 | 307篇 |
1991年 | 300篇 |
1990年 | 277篇 |
1989年 | 279篇 |
1988年 | 223篇 |
1987年 | 224篇 |
1986年 | 258篇 |
1985年 | 225篇 |
1984年 | 187篇 |
1983年 | 146篇 |
1982年 | 127篇 |
1979年 | 187篇 |
1978年 | 118篇 |
1977年 | 117篇 |
1975年 | 120篇 |
1974年 | 146篇 |
1973年 | 137篇 |
1972年 | 142篇 |
1971年 | 122篇 |
1970年 | 113篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
A rapid microagglutination test for the diagnosis of Legionella pneumophila (serogroup 1) infection 总被引:4,自引:3,他引:4 下载免费PDF全文
A rapid microagglutination test has been developed which can be performed in 30 minutes. Ninety-seven percent of 96 patients diagnosed as having Legionella pneumophila (serogroup 1) infection by indirect immunofluorescence were also detected by the rapid microagglutination test. 相似文献
102.
Martineau M Jalali GR Barber KE Broadfield ZJ Cheung KL Lilleyman J Moorman AV Richards S Robinson HM Ross F Harrison CJ 《Genes, chromosomes & cancer》2005,43(1):54-71
This study was undertaken in order to compare the interphase and metaphase cytogenetics of 28 patients with ETV6/RUNX1 positive acute lymphoblastic leukemia, at diagnosis and relapse. The median time to relapse was 26 months. The significant fusion positive population heterogeneity revealed at interphase by a commercial probe for ETV6/RUNX1 fusion has not been described before. Six diagnostic samples had a single abnormal population; others had up to five each, which differed in the numbers of RUNX1 signals, and in the retention or loss of the second ETV6 signal. In contrast, the number of fusion signals was more constant. At relapse, there were fewer populations; the largest or unique clone was sometimes a re-emergence of a minor, diagnostic one, with a retained copy of ETV6 and the most RUNX1 signals. Abnormal, fusion negative clones were identified in bone marrow samples at extra-medullary relapse. Variant three or four-way translocations, which involved chromosomes 12 and 21, were prominent among the complex rearrangements revealed by metaphase FISH. The frequency of their occurrence at diagnosis and reappearance at relapse, sometimes accompanied by minor clonal evolution, was another new observation. Other recurrent cytogenetic features included a second copy of the fusion signal in six cases, partial duplication of the long arm of the X chromosome in two cases, and trisomy 10 in three cases. In comparing our data with previously reported cases, a picture is beginning to emerge of certain diagnostic features, which may provide circumstantial evidence of an increased risk of relapse. 相似文献
103.
Mannering SI Dromey JA Morris JS Thearle DJ Jensen KP Harrison LC 《Journal of immunological methods》2005,298(1-2):83-92
T-cell clones are valuable tools for investigating T-cell specificity in infectious, autoimmune and malignant diseases. T cells specific for clinically-relevant autoantigens are difficult to clone using traditional methods. Here we describe an efficient method for cloning human autoantigen-specific CD4+ T cells pre-labelled with CFSE. Proliferating, antigen-responsive CD4+ cells were identified flow cytometrically by their reduction in CFSE staining and single cells were sorted into separate wells. The conditions (cytokines, mitogens and tissue culture plates) for raising T-cell clones were optimised. Media supplemented with IL-2+IL-4 supported growth of the largest number of antigen-specific clones. Three mitogens, PHA, anti-CD3 and anti-CD3+anti-CD28, each stimulated the growth of similar numbers of antigen-specific clones. Cloning efficiency was similar in flat- and round-bottom plates. Based on these findings, IL-2+IL-4, anti-CD3 and round-bottom plates were used to clone FACS-sorted autoantigen-specific CFSE-labelled CD4+ T cells. Sixty proinsulin- and 47 glutamic acid decarboxylase-specific clones were obtained from six and two donors, respectively. In conclusion, the CFSE-based method is ideal for cloning rare, autoantigen-specific, human CD4+ T cells. 相似文献
104.
Tumor Vascularity Is Not a Prognostic Factor for Malignant Melanoma of the Skin 总被引:1,自引:4,他引:1 下载免费PDF全文
Klaus J. Busam Marianne Berwick Karen Blessing Katrin Fandrey Sewon Kang Themis Karaoli Judy Fine Alistair J. Cochran Wain L. White Jason Rivers David E. Elder Duan-Ren Po Wen Bradley H. Heyman Raymond L. Barnhill 《The American journal of pathology》1995,147(4):1049-1056
Tumor vascularity has been proposed as a prognostic indicator for a number of solid tumors. Although a correlation between microvessel number and metastatic behavior has also been suggested for cutaneous melanoma, the small number of cases studied to date allows one to draw only preliminary conclusions. In this study, we have assessed tumor vascularity in cutaneous melanoma by comparing 60 cases of metastasizing and non-metastasizing tumors matched for tumor thickness, age, sex, and anatomic site. Ulex europaeus agglutinin I appeared to be the most suitable vascular marker for this study. Our results indicate that there was no statistically significant difference between the two groups with regard to tumor vascularity. Even after identifying 15 cases of thin (<1.0 mm thick) melanoma, there was no significant difference in the number of microvessels between metastasizing and non-metastasizing tumors. Comparison of patterns of vascular microarchitecture also failed to discriminate between the two groups. Thus, our results indicate that tumor vascularity may not be an independent prognostic factor for cutaneous melanoma. 相似文献
105.
Anca Ram Qiuhe Cao Paul E. Keck Harrison G. Pope Koichi Otani Gerard Addonizio Susan L. McElroy Sunao Kaneko Michaela Redlichova Elliot S. Gershon Pablo V. Gejman 《American journal of medical genetics. Part A》1995,60(3):228-230
Dysfunction of the dopaminergic system has been suggested as a pathogenic mechanism in neuroleptic malignant syndrome. Therefore, we examined the complete coding sequences of the dopamine D2 receptor (DRD2) gene for structural abnormalities in 12 patients with a history of NMS, including two cases of familial NMS. Mutational analysis was performed by denaturing gradient gel electrophoresis (DGGE), a highly sensitive technique for detecting sequence differences. We found in one patient with a history of NMS a nucleotide substitution at codon 310 (CCG→TCG) of exon 7 of the DRD2 gene which predicts the replacement of proline to serine in the third cytoplasmic loop of the receptor, a part of the receptor that interacts with G-proteins. A larger series of patients with NMS needs to be investigated to establish whether this allele is associated with an increased susceptibility to NMS. © 1995 Wiley-Liss, Inc. 相似文献
106.
Genotypic variation in the Bordetella pertussis virulence factors pertactin and pertussis toxin in historical and recent clinical isolates in the United Kingdom 总被引:1,自引:0,他引:1 下载免费PDF全文
Fry NK Neal S Harrison TG Miller E Matthews R George RC 《Infection and immunity》2001,69(9):5520-5528
The reemergence of pertussis has been reported in several countries despite high vaccination coverage. Studies in The Netherlands and Finland have investigated polymorphism in the genes coding for two important virulence factors of Bordetella pertussis, pertactin and pertussis toxin, and identified the emergence and subsequent dominance in circulating strains of pertactin and toxin variants not found in the whole-cell vaccine (WCV). The study described here investigated whether such variation had occurred in the United Kingdom, which presently has low levels of pertussis. Sequence analysis of the genes for pertactin (prnA) and the pertussis toxin S1 subunit (ptxA) among isolates of B. pertussis from 285 United Kingdom patients, from 1920 to 1999, revealed three prnA variants, prnA(1), prnA(2), and prnA(3), and two ptxA variants, ptxA(1) and ptxA(2), showing differences in nucleic acid sequence. The proportion of pertactin gene types not included in the United Kingdom WCV, i.e., prnA(2) and prnA(3), has increased in recent years and was found in 21 of 86 (24%) strains from the 1980s and 56 of 105 (53%) strains from the 1990s. To date, the presence of these nonvaccine prnA types has not been associated with a resurgence of pertussis in the United Kingdom. The distribution of prnA and ptxA types in The Netherlands, Finland, and the United Kingdom in the 1990s is distinct. The most striking difference in the United Kingdom isolates is that all 105 of the most recent circulating strains (from 1998 to 1999) are of a pertussis toxin type found in the United Kingdom WCV, i.e., ptxA(1). 相似文献
107.
108.
109.
L E Scheving W H Harrison P Gordon J E Pauly 《The American journal of physiology》1968,214(1):166-173
110.
BACKGROUND: Young adults with early-onset major depressive disorder (MDD) may be at high risk of progression to bipolar disorder. Although hypomanic symptoms are common in young people with depression, many do not reach the strict DSM-IV and ICD-10 criteria for hypomania. We used an emerging innovative framework for bipolar spectrum to evaluate this question. METHODS: Consecutive referrals to a psychiatric outpatient clinic at a university health service were assessed for recurrent episodes of depression. DSM-IV diagnoses were based on a SCID-1 interview. We used two approaches to delineate bipolar spectrum. The first focused on bipolar spectrum disorder (BSD, as defined by Ghaemi et al. [Can. J. Psychiatry 47 (2002) 125]), and the second on a symptoms perspective based on MDD with a history of hypomanic symptoms, using a 15-point hypomanic symptoms checklist with a cut-off > or =8 or more symptoms (modified from J. Affect. Disord. 73 (2003) 39 and J. Affect. Disord. 73 (2003) 73). Data were also obtained on family history of affective disorder, course and number of episodes of depression, symptom severity, psychosocial functioning, suicidality and deliberate self-harm, and drug and alcohol use. RESULTS: High rates of bipolar and bipolar spectrum disorder were identified. Under DSM-IV, 14 subjects (16.1%) had bipolar affective disorder and 73 subjects (83.9%) had recurrent MDD. Depending on the method used to diagnose bipolar spectrum, between 47.1% and 77.0% of the total cohort could be so diagnosed. Hypomanic symptom counts, irrespective of duration, yielded the highest estimates for bipolar spectrum. High rates of pharmacological hypomania were also identified: 12 subjects (16.4%) with recurrent MDD group reported this, and all could be diagnosed with bipolar spectrum. LIMITATIONS: The reliability of using the 15-point hypomanic scale for the diagnostic assignments was not tested. All subjects were recruited from a university health service and, given the affluence of their parents, findings may not generalise to other populations. Most importantly, because bipolar family history and pharmacological hypomania were part of the diagnostic criteria of the BSD group, they could not be used as external validators for Ghaemi's BSD construct. CONCLUSIONS: Bipolar disorders emerge as extremely common in this cohort of young adults with recurrent depression. Antidepressant-induced hypomania and high scores on a hypomanic symptoms checklist help to identify patients who are likely to have a bipolar spectrum illness, but who do not meet DSM-IV criteria for bipolar disorder. This is a preliminary study, and further evidence from external validating strategies are needed to verify the bipolar status of these patients in a larger and unselected cohort representing a broader socio-economic demographic profile. 相似文献