全文获取类型
收费全文 | 857篇 |
免费 | 41篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 40篇 |
妇产科学 | 9篇 |
基础医学 | 81篇 |
口腔科学 | 13篇 |
临床医学 | 66篇 |
内科学 | 193篇 |
皮肤病学 | 27篇 |
神经病学 | 31篇 |
特种医学 | 181篇 |
外科学 | 65篇 |
综合类 | 34篇 |
预防医学 | 21篇 |
眼科学 | 11篇 |
药学 | 63篇 |
中国医学 | 7篇 |
肿瘤学 | 63篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 11篇 |
2021年 | 23篇 |
2020年 | 6篇 |
2019年 | 22篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 29篇 |
2015年 | 54篇 |
2014年 | 28篇 |
2013年 | 43篇 |
2012年 | 41篇 |
2011年 | 44篇 |
2010年 | 37篇 |
2009年 | 30篇 |
2008年 | 31篇 |
2007年 | 29篇 |
2006年 | 22篇 |
2005年 | 25篇 |
2004年 | 14篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 23篇 |
1997年 | 42篇 |
1996年 | 34篇 |
1995年 | 28篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 3篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1955年 | 2篇 |
1948年 | 1篇 |
排序方式: 共有908条查询结果,搜索用时 15 毫秒
11.
Dietary polyamines promote the growth of azoxymethane-induced aberrant crypt foci in rat colon 总被引:1,自引:1,他引:1
We have examined whether dietary polyamines influence the formation and
initial growth of azoxymethane (AOM)-induced aberrant crypt foci (ACF) in
rat colon. Effects of a combination of dietary polyamines at three dose
levels (putrescine: 50, 280, 740 nmol/g; spermidine: 10, 261, 763 nmol/g;
spermine: 1, 31, 91 nmol/g) in the polyamine-poor AIN-76A diet were studied
in animals in two different experimental situations: animals treated with
AOM alone and animals treated with AOM + difluoromethylornithine (DFMO), a
specific inhibitor of endogenous polyamine synthesis. In both experimental
situations, dietary polyamines enhanced the growth of ACF, expressed as the
number of large ACF (foci with three or more aberrant crypts, ACF > or =
3), whereas the formation of ACF, expressed as the number of ACF, was
apparently not altered. In animals treated with AOM alone, maximal growth
enhancing effect on ACF was nearly obtained with the median level of
dietary polyamine. In rats fed a low polyamine diet, basic AIN-76A, DFMO
reduced the growth of AOM-induced ACF by 83%. This inhibitory effect of
DFMO was counteracted by dietary polyamines in a dose- dependent manner,
and it was abolished at the highest level of polyamines. In conclusion, it
was demonstrated that dietary polyamines are able to enhance the growth of
AOM-induced ACF. Further, dietary polyamines reversed the DFMO-caused
inhibition of ACF growth, probably by compensating for the DFMO-reduced
endogenous polyamine synthesis.
相似文献
12.
13.
14.
目的:性治疗法目前尚未普及,本研究旨在评价性治疗法联合西地那非治疗勃起功能障碍(ED)的疗效。方法:根据治疗方法的不同将在本院治疗随访过的3130例维吾尔族ED患者分成2组。对照组625例,单纯口服西地那非3个月;试验组2505例,采用性治疗法联合西地那非治疗3个月。采用国际勃起功能问卷表(IIEF-5)在各组治疗前、后进行疗效评估,并随访12个月。结果:对照组治疗前、后及在6个月、12个月随访的IIEF-5评分分别为12.80±3.76、18.10±2.61、17.35±2.73和16.64±2.63;试验组治疗前、后及在6个月、12个月随访的IIEF-5评分分别为12.73±3.52、19.06±4.07、19.86±2.42和20.47±2.38。两组治疗前后IIEF-5评分自身对比差异均有显著性(P<0.05)。组间比较,试验组较对照组6个月和12个月随访IIEF-5评分均有显著性差异(P<0.05)。结论:性治疗法联合西地那非治疗ED的效果优于单纯西地那非治疗,并在12个月的随访中稳定性良好。 相似文献
15.
Factor V and factor VIII are homologous cofactors in the blood coagulation cascade that have the domain structure A1-A2-B-A3-C1-C2, of which the B domain has extensively diverged. In transfected COS-1 monkey cells, expression of factor VIII is approximately 10-fold less efficient than that of factor V, primarily because of inefficient protein secretion and, to a lesser extent, reduced mRNA expression. To study the functional significance and effect of the B domain on expression and activity, chimeric cDNAs were constructed in which the B domains of factor V and factor VIII were exchanged. Expression of a factor VIII chimera harboring the B-domain of factor V yielded a fully functional factor VIII molecule that was expressed twofold more efficiently than wild-type factor VIII because of increased mRNA expression. Thus, sequences within the factor VIII B domain were not responsible for the inefficient secretion of factor VIII compared with factor V. Expression of a factor V chimera harboring the B domain of factor VIII was slightly reduced compared with wild-type factor V, although the secreted molecule had significantly reduced procoagulant activity correlating with dissociated heavy and light chains and resistance to thrombin activation. Interestingly, the factor V chimera containing the factor VIII B domain was efficiently activated by Russell's viper venum (RVV). A factor V B domain deletion (residues 710- 1545) molecule also exhibited significantly reduced procoagulant activity caused by resistance to thrombin cleavage and activation, although this molecule was activatable by RVV. These results show that, in contrast to factor VIII, thrombin activation of factor V requires sequences within the B domain. In addition, thrombin activation of factor V occurs through a different mechanism than activation by RVV. 相似文献
16.
Identification of the molecular defect in the erythrocyte membrane skeleton of some kindreds with hereditary spherocytosis 总被引:12,自引:0,他引:12
We have localized the molecular alteration in the membrane skeleton of two of four kindreds with hereditary spherocytosis (HS) to an alteration in the spectrin-protein-4.1 interaction due to a defective spectrin molecule. The defective spectrin-protein-4.1 interaction in these kindreds (referred to as type I HS) leads to a weakened spectrin- protein-4.1-actin ternary complex, which in turn may lead to the friable membrane skeleton and suggested membrane instability related to this disorder. Type I HS spectrin binds approximately 63% as much protein-4.1 as normal spectrin (with equal affinity). This defect does not correlate with splenic function or erythrocyte age in the circulation. However, the approximately 37% reduction in binding of protein-4.1 to HS spectrin approaches the theoretical value of 50% expected in this autosomal dominant disorder. All other type I membrane skeletal interactions (spectrin-syndein, spectrin heterodimer- heterodimer, syndein-band-3) were found to be normal. It would appear therefore that the defective HS spectrin-protein-4.1 interaction in type I hereditary spherocytosis may be the primary molecular defect rather than a secondary phenomena. 相似文献
17.
Gain of chromosome 1q (+1q) is one of the most common recurrent cytogenetic abnormalities in multiple myeloma (MM), occurring in approximately 40% of newly diagnosed cases. Although it is often considered a poor prognostic marker in MM, +1q has not been uniformly adopted as a high-risk cytogenetic abnormality in guidelines. Controversy exists regarding the importance of copy number, as well as whether +1q is itself a driver of poor outcomes or merely a common passenger genetic abnormality in biologically unstable disease. Although the identification of a clear pathogenic mechanism from +1q remains elusive, many genes at the 1q21 locus have been proposed to cause early progression and resistance to anti-myeloma therapy. The plethora of potential drivers suggests that +1q is not only a causative factor or poor outcomes in MM but may be targetable and/or predictive of response to novel therapies. This review will summarize our current understanding of the pathogenesis of +1q in plasma cell neoplasms, the impact of 1q copy number, identify potential genetic drivers of poor outcomes within this subset, and attempt to clarify its clinical significance and implications for the management of patients with multiple myeloma.Subject terms: Cancer genomics, Myeloma, Myeloma 相似文献
18.
再发骨质疏松性椎体压缩骨折保守治疗患者出院后生存质量 总被引:1,自引:0,他引:1
目的:对比初次和再发骨质疏松性椎体压缩骨折(osteoporotic vertebral compression fractures,OVCFs)患者保
守治疗的生存质量,了解再次骨折对此类患者生存质量各方面的影响。方法:回顾性观察治疗OVCFs后出现再骨折
的患者30名(再骨折组)和同时期行保守治疗OVCFs后未发生再骨折的基本条件相似的患者30例(对照组),比较两组出
院后3个月时SF-36简明健康健康状况调查表的调查结果。结果:再骨折组治疗后的8个维度均不同程度较对照组变差
(均P<0.01)。结论:再骨折组患者的生存质量明显低于对照组,并且会进一步影响患者的心理预期、情绪和社会活动
的各个方面。 相似文献
19.
Ahmed Najeeb Sadeq Alyaa Marafi Fahad Gnanasegaran Gopinath Usmani Sharjeel 《Annals of nuclear medicine》2022,36(4):329-339
Annals of Nuclear Medicine - 18F-Sodium fluoride (18F-NaF) is a PET tracer that is mostly used in the evaluation of bone metastasis in oncology cases. Recently, 18F-NaF PET/CT is gaining wide... 相似文献