全文获取类型
收费全文 | 179198篇 |
免费 | 12758篇 |
国内免费 | 4452篇 |
专业分类
耳鼻咽喉 | 2541篇 |
儿科学 | 2715篇 |
妇产科学 | 2357篇 |
基础医学 | 25265篇 |
口腔科学 | 3959篇 |
临床医学 | 17930篇 |
内科学 | 29165篇 |
皮肤病学 | 4615篇 |
神经病学 | 12935篇 |
特种医学 | 9488篇 |
外国民族医学 | 19篇 |
外科学 | 23204篇 |
综合类 | 11318篇 |
现状与发展 | 23篇 |
一般理论 | 34篇 |
预防医学 | 11033篇 |
眼科学 | 4180篇 |
药学 | 16959篇 |
60篇 | |
中国医学 | 5064篇 |
肿瘤学 | 13544篇 |
出版年
2024年 | 186篇 |
2023年 | 1349篇 |
2022年 | 2410篇 |
2021年 | 6977篇 |
2020年 | 4154篇 |
2019年 | 4565篇 |
2018年 | 5387篇 |
2017年 | 4674篇 |
2016年 | 5448篇 |
2015年 | 7998篇 |
2014年 | 9516篇 |
2013年 | 10963篇 |
2012年 | 16308篇 |
2011年 | 16081篇 |
2010年 | 9995篇 |
2009年 | 8500篇 |
2008年 | 11251篇 |
2007年 | 10485篇 |
2006年 | 9487篇 |
2005年 | 8528篇 |
2004年 | 7160篇 |
2003年 | 6354篇 |
2002年 | 5324篇 |
2001年 | 3929篇 |
2000年 | 3558篇 |
1999年 | 2707篇 |
1998年 | 1215篇 |
1997年 | 968篇 |
1996年 | 765篇 |
1995年 | 711篇 |
1994年 | 571篇 |
1993年 | 473篇 |
1992年 | 915篇 |
1991年 | 857篇 |
1990年 | 778篇 |
1989年 | 678篇 |
1988年 | 564篇 |
1987年 | 566篇 |
1986年 | 410篇 |
1985年 | 447篇 |
1984年 | 340篇 |
1983年 | 250篇 |
1982年 | 188篇 |
1981年 | 218篇 |
1980年 | 176篇 |
1979年 | 272篇 |
1978年 | 208篇 |
1976年 | 163篇 |
1975年 | 162篇 |
1974年 | 181篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
目的 对比研究朝鲜淫羊藿酸性多糖酯化还原前后的理化特性,并探讨其改善油酸诱导的肝癌HepG2细胞脂质堆积活性的差异。方法 采用高效凝胶渗透色谱法测定朝鲜淫羊藿酸性多糖(EFPA)的均一性和分子量,高效液相色谱法测定EFPA和酯化还原后朝鲜淫羊藿酸性多糖(EFPA-R)的单糖组成;采用油酸(OA)处理HepG2细胞诱导建立脂质蓄积模型,不同浓度EFPA与EFPA-R(10、30、100、300 μg·mL-1)分别和OA共同作用于细胞24 h,采用CCK-8试剂盒测定细胞存活率,油红O染色观察细胞内脂滴蓄积情况,并采用试剂盒测定细胞内总胆固醇(TC)、甘油三酯(TG)含量。结果 EFPA为成分均一的多糖组分,分子量为125.8 kDa,由甘露糖、葡萄糖、半乳糖、葡萄糖醛酸和阿拉伯糖组成,摩尔比为1.7∶7.4∶1.4∶1.8∶1.0,葡萄糖占比最大,EFPA-R由甘露糖、葡萄糖、半乳糖和阿拉伯糖组成,摩尔比为0.8∶10.6∶2.1∶1.0;在10-300 μg·mL-1范围内,EFPA和EFPA-R对HepG2细胞的抑制作用较弱,作为给药浓度;与空白组相比,模型组细胞中TC、TG含量显著升高(P < 0.01),细胞内红色脂滴显著增多,与模型组相比,EFPA可显著降低细胞中TC、TG含量(P < 0.01),明显减少细胞内红色脂滴(P < 0.05或P < 0.01),EFPA-R干预后细胞则无明显变化。结论 EFPA可明显改善HepG2细胞脂质堆积情况,且呈现剂量依赖性,而半乳糖醛酸(GalA)的存在可能是其抑制HepG2细胞脂质蓄积的关键因素。 相似文献
2.
Xiao-Long Tang Yan-Dong Miao Deng-Hai Mi 《World journal of gastrointestinal oncology》2022,14(1):366-368
The present letter to the editor is in response to the research “Outcomes of curative liver resection for hepatocellular carcinoma in patients with cirrhosis” by Elshaarawy et al in World J Gastroenterol 2021; 13(5): 424–439. The preoperative assessment of the liver reserve function in hepatocellular carcinoma (HCC) patients with cirrhosis is crucial, and there is no universal consensus on how to assess it. Based on a retrospective study, Elshaarawy et al investigated the impact of various classical clinical indicators on liver failure and the prognosis after hepatectomy in HCC patients with cirrhosis. We recommend that we should strive to explore new appraisal indicators, such as the indocyanine green retention rate at 15 min. 相似文献
3.
Kim Wonse Park Heungju Park Jin Joo Kook Woong 《Social psychiatry and psychiatric epidemiology》2022,57(1):47-56
Social Psychiatry and Psychiatric Epidemiology - The negative effect of catastrophic financial loss on suicide risk is widely perceived but hardly studied in-depth because of various difficulties... 相似文献
4.
6.
Patrick W. Keeley Mikayla C. Lebo Jordan D. Vieler Jason J. Kim Ace J. St. John Benjamin E. Reese 《The Journal of neuroscience》2021,41(1):103
Amacrine cells of the retina are conspicuously variable in their morphologies, their population demographics, and their ensuing functions. Vesicular glutamate transporter 3 (VGluT3) amacrine cells are a recently characterized type of amacrine cell exhibiting local dendritic autonomy. The present analysis has examined three features of this VGluT3 population, including their density, local distribution, and dendritic spread, to discern the extent to which these are interrelated, using male and female mice. We first demonstrate that Bax-mediated cell death transforms the mosaic of VGluT3 cells from a random distribution into a regular mosaic. We subsequently examine the relationship between cell density and mosaic regularity across recombinant inbred strains of mice, finding that, although both traits vary across the strains, they exhibit minimal covariation. Other genetic determinants must therefore contribute independently to final cell number and to mosaic order. Using a conditional KO approach, we further demonstrate that Bax acts via the bipolar cell population, rather than cell-intrinsically, to control VGluT3 cell number. Finally, we consider the relationship between the dendritic arbors of single VGluT3 cells and the distribution of their homotypic neighbors. Dendritic field area was found to be independent of Voronoi domain area, while dendritic coverage of single cells was not conserved, simply increasing with the size of the dendritic field. Bax-KO retinas exhibited a threefold increase in dendritic coverage. Each cell, however, contributed less dendrites at each depth within the plexus, intermingling their processes with those of neighboring cells to approximate a constant volumetric density, yielding a uniformity in process coverage across the population.SIGNIFICANCE STATEMENT Different types of retinal neuron spread their processes across the surface of the retina to achieve a degree of dendritic coverage that is characteristic of each type. Many of these types achieve a constant coverage by varying their dendritic field area inversely with the local density of like-type neighbors. Here we report a population of retinal amacrine cells that do not develop dendritic arbors in relation to the spatial positioning of such homotypic neighbors; rather, this cell type modulates the extent of its dendritic branching when faced with a variable number of overlapping dendritic fields to approximate a uniformity in dendritic density across the retina. 相似文献
7.
8.
经皮椎体成形术是一种安全有效的微创手术,腹膜后血肿是其罕见但严重的并发症。我们报告一例经皮椎体成形术RH阴性(熊猫血)患者术后并发巨大腹膜后血肿,经保守和输血等支持治疗,病人康复出院。脊柱医生应了解这种罕见但潜在致命的并发症,因为早期认识和及时预防是降低其发病率的基础。 相似文献
9.
10.
Comprehensive evidence regarding the treatment of non-anaemic iron deficiency in patients undergoing valvular heart surgery is lacking. This study aimed to investigate the association between non-anaemic iron deficiency and postoperative outcomes in these patients. We retrospectively analysed 321 patients of which 180 (56%) had iron deficiency (defined as serum ferritin < 100 ng.ml-1 or < 300 ng.ml-1 with transferrin saturation < 20%). While the iron-deficient group had lower pre-operative haemoglobin levels than the non-iron deficient group (median (IQR [range]) 134 (127–141 [120–172]) g.l-1, 143 (133–150 [120–179]) g.l-1, p = 0.001), there was no between-group difference in allogeneic red blood cell transfusion. Median (IQR [range]) days alive and out of hospital at postoperative day 90 was 1 day shorter in the iron-deficient group (80 (77–82 [9–85]) days vs. 81 (79–83 [0–85]) days, p = 0.026). In multivariable analysis, only cardiopulmonary bypass duration (p = 0.032) and intra-operative allogeneic red blood cell transfusion (p = 0.011) were significantly associated with reduced days alive and out of hospital at postoperative day 90. Iron deficiency did not exert any adverse influence on secondary outcomes except length of hospital stay. Our findings indicate that non-anaemic iron deficiency alone is not associated with adverse effects in patients undergoing valvular heart surgery when it does not translate into an increased risk of allogeneic transfusion. 相似文献