全文获取类型
收费全文 | 1380篇 |
免费 | 64篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 41篇 |
妇产科学 | 31篇 |
基础医学 | 203篇 |
口腔科学 | 37篇 |
临床医学 | 108篇 |
内科学 | 218篇 |
皮肤病学 | 16篇 |
神经病学 | 136篇 |
特种医学 | 132篇 |
外科学 | 210篇 |
综合类 | 55篇 |
预防医学 | 59篇 |
眼科学 | 85篇 |
药学 | 98篇 |
中国医学 | 1篇 |
肿瘤学 | 37篇 |
出版年
2021年 | 17篇 |
2020年 | 8篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 23篇 |
2014年 | 14篇 |
2013年 | 43篇 |
2012年 | 41篇 |
2011年 | 37篇 |
2010年 | 39篇 |
2009年 | 43篇 |
2008年 | 39篇 |
2007年 | 82篇 |
2006年 | 82篇 |
2005年 | 54篇 |
2004年 | 66篇 |
2003年 | 55篇 |
2002年 | 57篇 |
2001年 | 54篇 |
2000年 | 46篇 |
1999年 | 42篇 |
1998年 | 40篇 |
1997年 | 43篇 |
1996年 | 50篇 |
1995年 | 28篇 |
1994年 | 24篇 |
1993年 | 25篇 |
1992年 | 23篇 |
1991年 | 11篇 |
1990年 | 15篇 |
1989年 | 31篇 |
1988年 | 21篇 |
1987年 | 21篇 |
1986年 | 23篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1973年 | 6篇 |
1972年 | 8篇 |
1970年 | 6篇 |
1933年 | 7篇 |
排序方式: 共有1470条查询结果,搜索用时 15 毫秒
1.
Coronary artery bypass grafts: visualization with MR imaging 总被引:1,自引:0,他引:1
2.
Propofol for patients with Huntington''s chorea? 总被引:2,自引:0,他引:2
3.
4.
5.
The perception of moving objects and our successful interaction with them entail that the visual system integrates shape and motion information about objects. However, neuroimaging studies have implicated different human brain regions in the analysis of visual motion (medial temporal cortex; MT/MST) and shape (lateral occipital complex; LOC), consistent with traditional approaches in visual processing that attribute shape and motion processing to anatomically and functionally separable neural mechanisms. Here we demonstrate object-selective fMRI responses (higher responses for intact than for scrambled images of objects) in MT/MST, and especially in a ventral subregion of MT/MST, suggesting that human brain regions involved mainly in the processing of visual motion are also engaged in the analysis of object shape. 相似文献
6.
7.
Genotype-phenotype correlation for nucleotide substitutions in the IgII- IgIII linker of FGFR2 总被引:6,自引:3,他引:3
8.
P D Williams M G Bock R D Tung V M Garsky D S Perlow J M Erb G F Lundell N P Gould W L Whitter J B Hoffman 《Journal of medicinal chemistry》1992,35(21):3905-3918
A new structural class of cyclic hexapeptide oxytocin antagonists derived from Streptomyces silvensis and typified by L-365,209 (cyclo-[L-prolyl1-D-phenylalanyl2-L- isoleucyl3-D-dehydropiperazyl4-L-dehydroperazyl5-D-(N- methyl)phenylalanyl6]) was recently reported. In this paper we further delineate the structure-activity profile for this new class by systematic study of L-365,209 analogs obtained by total synthesis. The optimal combination of cyclic amino acid ring sizes at positions 1, 4, and 5 and the role of the N-alkyl substituent at position 6 was elucidated. The lipophilic amino acids at positions 2 and 3 and the unusual amino acid D-dehydropiperazic acid at position 4 were found to be the most critical residues for obtaining good oxytocin receptor affinity. Analogs containing a basic side chain at the less critical 5- and 6-positions maintained good receptor affinity and also had useful levels of water solubility for intravenous formulation. By combining potency- and solubility-enhancing substitutions, several analogs were identified that have the desired combination of properties in vitro (22, cyclo-[L-prolyl-D-tryptophanyl-L-isoleucyl-D-pipecolyl-L-pipeco lyl-D- histidyl]; 25, cyclo-[L-prolyl-D-2-naphthylalanyl-L-isoleucyl-D-pipecolyl-L -pipecolyl-D- histidyl]; 26, cyclo-[L-prolyl-D-tryptophanyl-L-isoleucyl-D-dehydropiperazyl-L-++ pipecolyl-D-histidyl]; 33, cyclo-[L-prolyl-D-tryptophanyl-L-isoleucyl-D-pipecolyl-L- piperazinylcarboxy-D-(N-methyl)phenylalanyl]; 34, cyclo-[L-prolyl-D-phenylalanyl-L-isoleucyl-D-dehydropiperazyl-L-or nithyl- D-(N-methyl)phenylalanyl]). In general, this class exhibited good selectivity for binding to the oxytocin receptor versus the arginine vasopressin V1a and V2 receptor subtypes, although increased V2 receptor affinity was observed in one case (32, cyclo[L-prolyl-D-2-naphthylalanyl-L-isoleucyl-D-pipecolyl-L- lysyl-D-(N- methyl)phenylalanyl]). Unexpectedly, compound 33 was found to stimulate contractions of the isolated rat uterus via activation of the uterine bradykinin receptor. Compounds 22, 25, 26, 33, and 34 were found to be potent antagonists of oxytocin-stimulated contraction of the rat uterus in vitro and in vivo. Compounds 22 and 25 were additionally characterized as potent antagonists of oxytocin-stimulated uterine contractions in the near-term pregnant rhesus monkey. These studies thus demonstrate the selectivity and efficacy of certain members of this novel class of antagonists and suggest their use as pharmacological tools in further defining the role of oxytocin in both term and preterm labor. 相似文献
9.
10.
Kretschmer U Bonhagen K Debes GF Mittrücker HW Erb KJ Liesenfeld O Zaiss D Kamradt T Syrbe U Hamann A 《European journal of immunology》2004,34(11):3070-3081
Endothelial selectins are crucial for the recruitment of leukocytes into sites of inflammation. On T cells, ligands for selectins become induced upon differentiation into the effector/memory stage. Initial in vitro studies suggested a correlation between the Th1 phenotype and ligand expression, but whether this also holds true in vivo remained uncertain. We here analyzed selectin ligands on CD4+ T cells producing IFN-gamma, IL-4 or IL-10, prototypic cytokines of the Th1, Th2 and Tr1 subset, respectively. We analyzed mice infected with influenza virus, the bacterium Listeria, and the parasites Toxoplasma (all Th1 models) or Nippostrongylus (Th2 model). A link between the Th1 phenotype and ligand expression was not found in vivo. Surprisingly, the potentially regulatory IL-10-producing T cells displayed the highest frequency of ligand-positive cells in general. Within the inflamed tissues, the frequencies of P-selectin-binding cells increased in the dominant subset, either Th1 or Th2. Up-regulation was also found for E-selectin ligands during influenza, but not Nippostrongylus infection. In conclusion, conditions driving T cell polarization into either Th1 or Th2 in vivo do not affect the expression of selectin ligands, but acquisition of P-selectin binding and hence migration into inflamed tissues is boosted by an inflammatory milieu. 相似文献