全文获取类型
收费全文 | 4261篇 |
免费 | 291篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 375篇 |
妇产科学 | 109篇 |
基础医学 | 510篇 |
口腔科学 | 110篇 |
临床医学 | 443篇 |
内科学 | 970篇 |
皮肤病学 | 52篇 |
神经病学 | 280篇 |
特种医学 | 311篇 |
外科学 | 391篇 |
综合类 | 67篇 |
一般理论 | 14篇 |
预防医学 | 443篇 |
眼科学 | 52篇 |
药学 | 234篇 |
中国医学 | 2篇 |
肿瘤学 | 174篇 |
出版年
2022年 | 31篇 |
2021年 | 60篇 |
2020年 | 31篇 |
2019年 | 59篇 |
2018年 | 79篇 |
2017年 | 52篇 |
2016年 | 67篇 |
2015年 | 84篇 |
2014年 | 116篇 |
2013年 | 134篇 |
2012年 | 205篇 |
2011年 | 216篇 |
2010年 | 140篇 |
2009年 | 148篇 |
2008年 | 193篇 |
2007年 | 190篇 |
2006年 | 216篇 |
2005年 | 184篇 |
2004年 | 179篇 |
2003年 | 134篇 |
2002年 | 111篇 |
2001年 | 126篇 |
2000年 | 126篇 |
1999年 | 111篇 |
1998年 | 63篇 |
1997年 | 83篇 |
1996年 | 85篇 |
1995年 | 64篇 |
1994年 | 69篇 |
1993年 | 64篇 |
1992年 | 81篇 |
1991年 | 71篇 |
1990年 | 73篇 |
1989年 | 84篇 |
1988年 | 70篇 |
1987年 | 82篇 |
1986年 | 73篇 |
1985年 | 72篇 |
1984年 | 58篇 |
1983年 | 43篇 |
1982年 | 44篇 |
1981年 | 24篇 |
1980年 | 29篇 |
1979年 | 37篇 |
1978年 | 30篇 |
1977年 | 30篇 |
1976年 | 21篇 |
1975年 | 23篇 |
1974年 | 31篇 |
1973年 | 23篇 |
排序方式: 共有4558条查询结果,搜索用时 0 毫秒
31.
Natural killer cell (NK) activity, which is important in the defense against tumors and viral infections, is reduced in women undergoing conjugal bereavement. The relationship between NK activity and plasma cortisol was investigated in three groups of subjects: women who were anticipating the death of their husbands, women whose husbands had recently died, and controls. Bereaved women showed reduced NK activity and increased plasma cortisol levels as compared to controls. Anticipatory bereaved women also showed significant reductions in NK activity, but had levels of plasma cortisol comparable to those of controls. The reduction of NK activity during anticipatory and actual bereavement cannot be explained solely on the basis of increased cortisol secretion. 相似文献
32.
Optimal surgery remains the mainstay of best outcome for rectal cancer. The demonstration, during the 3rd Annual Pelican Surgical Workshop Symposium, of an abdomino‐perineal excision (APE) performed in the ‘Berlin position’, further added to the debate on optimal surgical technique. Much interest was created at the 1st Pelican symposium with the demonstration, by the Swedish surgeon Dr Torbjorn Holm, of a prone APE and the delivery of a ‘cylindrical’ specimen and the potential to reduce local recurrence using this approach. The high rates of local recurrence following APE and the discussions as to optimal technique have led to the development of a proposed MERCURY Study Group study to assess the benefit of a radical APE, with careful assessment of the impact that this operation may have on morbidity. A German study has also been proposed adopting the UK's multidisciplinary team approach. It aims at targeting preoperative chemoradiotherapy at those patients in whom a radical APE or total mesorectal excision is likely to result in an involved surgical resection margin. In this article we review the evidence for improving the surgical technique for low rectal cancer. We believe improvements may be best achieved through continued European prospective, multi‐centre, multidisciplinary studies. 相似文献
33.
34.
35.
Steenbergen EJ; Verhagen OJ; van Leeuwen EF; van den Berg H; von dem Borne AE; van der Schoot CE 《Blood》1995,86(2):692-702
Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL. 相似文献
36.
A M Daniels 《British medical journal》1998,317(7174):1728
37.
Picotamide inhibition of excess in vitro thromboxane B2 release by colorectal mucosa in inflammatory bowel disease. 总被引:1,自引:0,他引:1
Collins CE Benson MJ Burnham WR Rampton DS 《Alimentary pharmacology & therapeutics》1996,10(3):315-320
BACKGROUND: Inflammatory bowel disease is associated with increased mucosal release of eicosanoids. Among these, thromboxane A2 has been proposed as a possible inflammatory mediator; its suppression may be a useful therapeutic option. METHODS: Using a tissue incubation technique, we compared release of immunoreactive thromboxane B2 by colonic biopsies from patients with ulcerative colitis, Crohn's disease and controls, and assessed the inhibitory effect of picotamide, a thromboxane synthesis inhibitor-receptor antagonist, which has been widely used in Italy for management of ischaemic heart and cerebrovascular disease. RESULTS: Increased amounts of thromboxane B2 were released from biopsies from patients with active ulcerative colitis (median 238 pg/20 min/mg wet weight (interquartile range 147- 325), n = 12) and active Crohn's disease (252 (174-450), 6) compared with those from patients with quiescent ulcerative colitis (95 (61- 140), 12) or Crohn's disease (105 (57-201), 13), or controls (136 (64- 206), 8). Incubation with picotamide at concentrations between 100 microM and 1 mM reduced thromboxane B2 release (IC50 890 microM). CONCLUSION: Since increased thromboxane A2 production may have pathogenetic importance, thromboxane synthesis inhibitor-receptor antagonists such as picotamide merit therapeutic trial in the management of inflammatory bowel disease. 相似文献
38.
F Z Yetkin W M Mueller G L Morris T L McAuliffe J L Ulmer R W Cox D L Daniels V M Haughton 《AJNR. American journal of neuroradiology》1997,18(7):1311
PURPOSETo evaluate the spatial specificity of functional MR imaging by comparing it with intraoperative electrocortical mapping.METHODSFunctional MR imaging was performed in 28 patients before awake craniotomy and intraoperative electrocortical mapping. Activation was mapped for finger movement, lip movement, tongue movement, word generation, and counting paradigms. During surgery, finger movement, lip movement, tongue movement, counting, and/or speaking were mapped. The functional images and the photographic recordings of the brain functions mapped during surgery were converted to bit maps and coregistered by a computer program. The distance between the intraoperatively mapped function site and the MR activation site for a comparable function was measured.RESULTSForty-six functions were recorded on MR images and intraoperative maps. In 100% of correlations, the intraoperative site and the MR activation site were within 20 mm; in 87% of correlations they were within 10 mm. For each paradigm, 67% or more of the intraoperative stimulation maps correlated within 10 mm of the MR activation site.CONCLUSIONSFor the tasks used in this study, the activation site on functional MR images correlated well with the site at which intraoperative stimulation identified function. 相似文献
39.
40.