全文获取类型
收费全文 | 3955篇 |
免费 | 499篇 |
国内免费 | 256篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 144篇 |
妇产科学 | 28篇 |
基础医学 | 526篇 |
口腔科学 | 199篇 |
临床医学 | 228篇 |
内科学 | 1396篇 |
皮肤病学 | 42篇 |
神经病学 | 310篇 |
特种医学 | 25篇 |
外科学 | 182篇 |
综合类 | 248篇 |
现状与发展 | 5篇 |
预防医学 | 678篇 |
眼科学 | 19篇 |
药学 | 307篇 |
中国医学 | 233篇 |
肿瘤学 | 130篇 |
出版年
2024年 | 30篇 |
2023年 | 266篇 |
2022年 | 260篇 |
2021年 | 730篇 |
2020年 | 492篇 |
2019年 | 351篇 |
2018年 | 266篇 |
2017年 | 282篇 |
2016年 | 204篇 |
2015年 | 202篇 |
2014年 | 244篇 |
2013年 | 365篇 |
2012年 | 128篇 |
2011年 | 106篇 |
2010年 | 69篇 |
2009年 | 62篇 |
2008年 | 58篇 |
2007年 | 58篇 |
2006年 | 49篇 |
2005年 | 58篇 |
2004年 | 41篇 |
2003年 | 39篇 |
2002年 | 48篇 |
2001年 | 25篇 |
2000年 | 41篇 |
1999年 | 26篇 |
1998年 | 29篇 |
1997年 | 19篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 19篇 |
1993年 | 9篇 |
1992年 | 9篇 |
1991年 | 15篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有4710条查询结果,搜索用时 843 毫秒
11.
ABSTRACTAlthough exclusive breastfeeding has been linked to lower rates of postnatal HIV transmission compared to nonexclusive breastfeeding, mechanisms underlying this are unclear. Across a longitudinally sampled cohort of South African infants, we showed that exclusively breastfed (EBF) infants had altered gut bacterial communities when compared to nonexclusively breastfed (NEBF) infants, as well as reduced peripheral CD4 + T cell activation and lowered chemokine and chemokine receptor expression in the oral mucosa. We further demonstrated that the relative abundance of key taxa was correlated with peripheral CD4 + T cell activation. Here, we supplement those findings by using compositional data analyses to identify shifts in the abundance of several Bifidobacteria strains relative to select strains of Escherichia, Bacteroides, and others that are associated with the transition to NEBF. We illustrate that the abundance ratio of these taxa is tightly correlated with feeding modality and is a strong predictor of peripheral T cell activation. More broadly, we discuss our study in the context of novel developments and explore future directions for the field. 相似文献
12.
《Nutrition Clinique et Métabolisme》2020,34(2):130-140
Non alcoholic fatty liver disease or NAFLD is a disease with a large spectrum of liver injury that could appear in overweight or obese individuals with a metabolic syndrome. However, among overweight or obese, only a subset of individuals develops severe forms of NAFLD. Thus, the susceptibility of NAFLD is related to cofactors that could be protective or conversely noxious. Studies carried out in rodent models have demonstrated that the intestinal microbiota is a cofactor with a causal role in NAFLD. The bacterial patterns as well as the metabolites produced by intestinal bacteria are directly involved in the mediation of their effects, although the mechanisms are far from being fully identified. Changing intestinal microbiota by using fibers, prebiotics or probiotics can prevent or improve NAFLD in murine models. The translation of these data to human therapeutics is encouraging but remains limited. Indeed, there is clearly a dysbiosis associated with the different stages of NAFLD. The first clinical trials performed in patients to improve NAFLD showed beneficial effects although their analysis remains complicated given the many confounding factors, such as the use of metformin or proton inhibitors. A first clinical trial using a metabolite from Akkermansia muciniphila, suggests that new therapeutic approaches will emerge in the coming years based either on the modulation of the intestinal microbiota directly or on the modulation of intestinal microbiota targets. 相似文献
13.
14.
15.
16.
n. holmén † s. isaksson † m. simrén h. sjövall & l. öhman † 《Neurogastroenterology and motility》2007,19(2):119-125
17.
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
18.
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
19.
目的了解慎柔养真汤治疗老年性便秘患者的临床疗效及其对脑肠肽的影响。方法选择符合纳入标准的老年性便秘患者104例,随机分为2组各52例。治疗组予慎柔养真汤煎剂口服每日1剂,对照组予麻仁丸6 g口服每日3次,疗程8周。观察2组临床疗效,并比较治疗前后血浆P物质(SP)及血管活性肠肽(VIP)的变化。结果治疗后治疗组总有效率91%,对照组总有效率72%,2组比较有显著性差异(P<0.05)。治疗组治疗后血浆SP及VIP水平均显著升高(P均<0.01);对照组仅SP明显升高(P<0.05)。2组血浆SP及VIP比较有显著性差异(P均<0.05)。结论慎柔养真汤治疗老年性便秘患者临床疗效优于麻仁丸,可能与提高血浆SP及VIP水平相关。 相似文献
20.
慢性阻塞性肺疾病(COPD)是一种常见的慢性呼吸系统疾病,对人类健康造成极大威胁。研究发现,COPD患者与健康人群相比,肺部菌群及肠道菌群的组成结构发生了显著改变,导致黏膜屏障功能及机体免疫稳态被破坏,进而加重病情。积极调节肺部、肠道菌群平衡对于干预COPD的发生、发展有着至关重要的作用,但目前关于肺部、肠道菌群及其相互作用机制在COPD中作用的总结和认识还有待进一步阐明。本文就健康人群以及COPD患者肺部、肠道菌群的组成特点及可能的相互作用机制,以及现阶段基于肺部、肠道菌群及其相互作用防治COPD的最新研究成果进行综述,以期为COPD的发病机制、早期诊断、预防与治疗研究提供新思路。 相似文献