全文获取类型
收费全文 | 2599篇 |
免费 | 281篇 |
国内免费 | 90篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 81篇 |
妇产科学 | 12篇 |
基础医学 | 282篇 |
口腔科学 | 26篇 |
临床医学 | 156篇 |
内科学 | 650篇 |
皮肤病学 | 13篇 |
神经病学 | 228篇 |
特种医学 | 21篇 |
外科学 | 123篇 |
综合类 | 184篇 |
现状与发展 | 5篇 |
预防医学 | 691篇 |
眼科学 | 11篇 |
药学 | 227篇 |
1篇 | |
中国医学 | 198篇 |
肿瘤学 | 58篇 |
出版年
2024年 | 35篇 |
2023年 | 151篇 |
2022年 | 404篇 |
2021年 | 392篇 |
2020年 | 230篇 |
2019年 | 167篇 |
2018年 | 129篇 |
2017年 | 128篇 |
2016年 | 93篇 |
2015年 | 97篇 |
2014年 | 95篇 |
2013年 | 193篇 |
2012年 | 78篇 |
2011年 | 80篇 |
2010年 | 63篇 |
2009年 | 53篇 |
2008年 | 45篇 |
2007年 | 57篇 |
2006年 | 46篇 |
2005年 | 53篇 |
2004年 | 41篇 |
2003年 | 36篇 |
2002年 | 42篇 |
2001年 | 20篇 |
2000年 | 39篇 |
1999年 | 22篇 |
1998年 | 26篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 16篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有2970条查询结果,搜索用时 31 毫秒
1.
E. Likotrafiti K. M. Tuohy G. R. Gibson R. A. Rastall 《International journal of food sciences and nutrition》2016,67(2):83-91
The aim of the present study was to evaluate the antimicrobial activity of two synbiotic combinations, Lactobacillus fermentum with short-chain fructooligosaccharides (FOS-LF) and Bifidobacterium longum with isomaltooligosaccharides (IMO-BL), against enterohaemorrhagic Escherichia coli O157:H7 and enteropathogenic E. coli O86. Antimicrobial activity was determined (1) by co-culturing the synbiotics and pathogens in batch cultures, and (2) with the three-stage continuous culture system (gut model), inoculated with faecal slurry from an elderly donor. In the co-culture experiments, IMO-BL was significantly inhibitory to both E. coli strains, while FOS-LF was slightly inhibitory or not inhibitory. Factors other than acid production appeared to play a role in the inhibition. In the gut models, both synbiotics effectively inhibited E. coli O157 in the first vessel, but not in vessels 2 and 3. E. coli O86 was not significantly inhibited. 相似文献
2.
基于调控肠道菌群探讨中药防治脑卒中 总被引:3,自引:3,他引:0
肠道菌群是一个独特的生态系统,被称为人体"被遗忘的器官",被誉为人类的"第二基因组"。肠道菌群失调与许多中枢神经系统疾病相关,例如帕金森病、阿尔茨海默症、精神分裂症及多发性硬化等。脑卒中具有高的发病率、复发率、死亡率和致残率的特点。肠道菌群在脑卒中的发生、发展中起着关键的作用,可通过影响机体的吸收、代谢、血压、血糖、血脂及动脉粥样斑块等因素,进一步影响脑卒中的发病。中医认为脾胃气血流注失度、阴阳盛衰失衡,机体生理功能失调,化生"风、火、痰、虚、瘀"等病理产物,可致中风的发生。脾胃主腐熟运化水谷,肠道菌群影响饮食的消化吸收,现代研究的肠道菌群功能与中医之脾胃功能失调相关。因此,调整肠道菌群的稳态,可作为一个潜在的干预靶点预防和治疗缺血性脑卒中。中药干预脑卒中已经取得了很好的疗效,是否与调节肠道菌群有关,值得未来做进一步的研究。同时对中药有效成分(小檗碱、黄芩苷、白藜芦醇等),中药单方(丹参、红景天等)和中药组方(补阳还五汤、脑心通胶囊、补中益气汤等)防治脑缺血的研究进展进行综述,为缺血性脑卒中的预防和开发提供新的途径和思路。 相似文献
3.
4.
n. holmén † s. isaksson † m. simrén h. sjövall & l. öhman † 《Neurogastroenterology and motility》2007,19(2):119-125
5.
S. M. Manzurul Haque Kai Chen Noriaki Usui Yasuhiko Iiboshi Hiroomi Okuyama Akira Masunari Riichiro Nezu Yoji Takagi Akira Okada 《Surgery today》1997,27(6):500-505
The purpose of this study was to investigate the intestinal hemodynamics and gut glutamine metabolism during endotoxemia,
and their correlation with altered intestinal absorptive capacity and permeability. Seventeen Sprague-Dawley rats were used
in the study. The endotoxin group (ENDO) recieved endotoxin (10 mg/kg intraperitoneally,n=9), while the control group (CONT,n=8) received saline injection. Twelve hours later, D-xylose (0.5 g/kg) and fluorescein isothiocyanate-dextran (FITC-dextran,
750 mg/kg) were given by oral gavage. One hour later abdominal aortic (AA) blood flow, superior mesenteric venous (SMV) flow,
mean arterial pressure (MAP), central venous pressure (CVP), and SMV pressure (SMVP) were also measured. The MAP, AA, and
SMV blood flow decreased (P<0.05), while the CVP and SMVP increased (P<0.05) in the ENDO group as compared with the CONT group. The ENDO group showed significant decreases for both intestinal
glutaminase activity and net intestinal glutamine uptake (P<0.05). The D-xylose concentration in SMV decreased significantly (P<0.05) in the ENDO group as compared with the CONT group. However, the plasma FITC-dextran concentration showed no significant
difference between the groups. Endotoxin produced a hypodynamic effect in rats 12h after intraperitoneal administration in
association with both a decreased intestinal glutamine metabolism and an absorptive capacity. 相似文献
6.
David A. Sloan David M. Fleiszer Geoffrey K. Richards David Murray Rea A. Brown 《Journal of surgical oncology》1993,52(2):77-82
Sixty Sprague-Dawley rats were pair-fed one of three nutritionally identical diets. One diet contained “low-fiber” (3.8% crude fiber); the others contained “high fiber” (28.7% crude fiber) composed of either cellulose or lignin. Although both “high fiber” diets had similar stool bulking effects, only the cellulose diet was associated with a reduction in 1,2-dimethylhydrazine (DMH)-induced colon neoplasms. The cellulose diet was also associated with distinct changes in the gut bacterial profile and with a lowered serum cholesterol. © 1993 Wiley-Liss, Inc. 相似文献
7.
大气细菌粒子浓度的时间分布特征及最佳采样时间的研究 总被引:4,自引:0,他引:4
用MF-45型和HTK-201型空气微生物采样器分别在北京、天津和沈阳三地观测了不同季节和一天中大气细菌粒子的浓度及其变化。结果表明:京、津二地春季大气细菌粒子浓度高,分别为2053个/m3和2556个/m3;夏季低,分别为995个/m3和1064个/m3。沈阳秋季大气细菌粒子浓度高,为10108个/m3;冬季低,为1294个/m3。一天中,大气细菌粒子浓度呈双峰型变化,6:00~7:00和18:00时大气细菌粒子浓度高,11:00~13:00和1:00~2:00时大气细菌粒子浓度低。根据大气细菌粒子浓度的季节变化和一天中大气细菌粒子浓度的时间分布特征,经过京、津、沈三地一天中分别12次、8次、6次和4次不同采样时间组合的大气细菌粒子浓度的数理统计分析,大气细菌粒子浓度的监测拟集中在一年冬、春、夏、秋四季的中间月份,即1月、4月、7月、10月进行;一天中采样8次的时间序列可为7:00、10:00、13:00、16:00、19:00、22:00、1:00、4:00一天采样4次的时间序列可为5:00、11:00、17:00、23:00。白天采样4次的时间序列可为春、秋季6:00、9:00、12:00、15:00? 相似文献
8.
Patrizia Robino Ilario Ferrocino Giacomo Rossi Andrea Dogliero Valentina Alessandria Lisa Grosso 《Avian pathology》2019,48(2):111-120
Macrorhabdus ornithogaster is an opportunistic yeast that colonizes the gastric mucosa of many avian species. Until now, no studies have focused on the influence of a gastric infection on the balance of the intestinal microbiota of birds. In this study, 44 faecal samples from individual canaries, with and without M. ornithogaster infection, were analysed. The detection of the yeast was evaluated by 18S rRNA PCR. In order to evaluate the impact of the Macrorhabdus infection on the bacterial communities, culture-independent methods, by the use of amplicon-based sequencing as well as 16S rRNA-DGGE, were adopted. The different health status of animals affected the relative abundance of the main OTUs, with a greater diversification of the gut microbiota in healthy animals compared to the infected. In particular, Lactococcus, Pseudomonas, Acinetobacter, Lachnospiraceae, Propionibacterium and Weissella were found to be characteristic of uninfected animals (FDR?<?0.05), while Lactobacillus and Candidatus Arthromitus were characteristic of infected animals (FDR?<?0.05). Both these taxa have been reported as immunostimulatory, involved in immunological disorders. In infected animals the inferred metagenome assessed by PICRUST clearly showed a positive correlation between the presence of M. ornithogaster and KEGG genes related to ether lipid metabolism, already reported to be immunostimulatory by activation of macrophages and to play a pathophysiological role in several immunological disorders. Finally, our results show an interaction between infection of the digestive tract and intestinal microbiota of pet birds and provide insight into the changing of the complex enteric bacterial community.
- HIGHLIGHTS
Macrorabdus ornithogaster is a gastric yeast that colonizes a wide range of birds.
Differences were found between infected and healthy animals in gut microbiota.
Candidatus Arthromitus was closely associated with infected birds.
M. ornithogaster can affect intestinal microbiota composition of canaries.
9.
Masahiro Yasuda Shogo Tanaka Hiroshi Arakawa Yasuho Taura Yuichi Yokomizo Shigeo Ekino 《Anatomical record (Hoboken, N.J. : 2007)》2002,266(4):207-217
The calf contains two types of Peyer's patches (PPs): jejunal and ileal. The ileal PP has been thought to be equivalent to the bursa of Fabricius (BF) as a central lymphoid organ. The morphologies of ileal and jejunal PPs in the calf were compared with those of the BF and the caecal tonsil (CT) in the chicken. Immunoglobulin G–positive (IgG+) cells appear in the follicles of them all and exhibited a dendritic appearance after birth. We investigated whether the IgG in these follicles was produced in situ. IgG‐producing cells were detected in the follicular medullas of the jejunal PP and the CT, but not in those of the ileal PP and the BF. CD4+ cells were distributed in the follicular medullas of the jejunal PP and the CT, but not in those of the ileal PP and the BF. The data suggest that Ig class switching occurs in both jejunal PP follicles and CT follicles, but does not occur in either the ileal PP follicles or the bursal follicles. Because CD4+ T cells would be prerequisite for Ig class switching in these follicles, IgG+ cells of the follicular medullas in the ileal PP and the BF would trap immune complexes from the gut lumen. The primary B‐cell repertoire might be selected by gut‐derived antigens in the ileal PP and the BF before seeding the periphery. Anat Rec 266:207–217, 2002. © 2002 Wiley‐Liss, Inc. 相似文献
10.
Hepatocyte growth factor (HGF), a stimulator of angiogenesis and cell migration, regulates the growth of a wide variety of
cells by binding to its high-affinity receptor met and is involved in the growth and aggressiveness of several tumors. In
this study we investigated the expression of HGF and met in normal endocrine cells and related neoplasms of the gut and pancreas
to verify their possible role in tumor pathogenesis, growth, and aggressiveness. Normal tissues and 60 different endocrine
tumors were immunostained using specific antibodies directed against HGF, met, and various hormones. HGF immunoreactivity
(IR) was found in antroduodenal G cells, rectal enterochromaffin (EC) cells, and pancreatic A and B cells, whereas met IR
was detected in antral EC and G cells, and in pancreatic B cells; 46 of 60 tumors examined were positive for HGF, and they
were mainly represented by ECL-, EC-, and L-cell neoplasms. met IR was identified in 50/60 tumors of various phenotypes. HGF
and met coexpression was found in 42/60 cases, most of which were represented by EC-cell tumors. HGF/met coexpression was
significantly more frequent in ileolonic EC-cell tumors, which in the majority of cases were malignant, than in appendiceal
EC-cell tumors, which were all benign. Our results demonstrated, for the first time, that HGF and met are specifically distributed
in normal gut and pancreatic endocrine cells and, in addition, suggest that HGF and met may be implicated as autocrine/paracrine
factors regulating the growth of gastroenteropancreatic endocrine tumors, mainly of ileocolonic EC-cell carcinoids. 相似文献