全文获取类型
收费全文 | 6846篇 |
免费 | 375篇 |
国内免费 | 31篇 |
专业分类
耳鼻咽喉 | 61篇 |
儿科学 | 122篇 |
妇产科学 | 40篇 |
基础医学 | 852篇 |
口腔科学 | 163篇 |
临床医学 | 481篇 |
内科学 | 1885篇 |
皮肤病学 | 207篇 |
神经病学 | 444篇 |
特种医学 | 318篇 |
外科学 | 987篇 |
综合类 | 64篇 |
预防医学 | 248篇 |
眼科学 | 65篇 |
药学 | 471篇 |
中国医学 | 9篇 |
肿瘤学 | 835篇 |
出版年
2023年 | 35篇 |
2022年 | 85篇 |
2021年 | 145篇 |
2020年 | 82篇 |
2019年 | 93篇 |
2018年 | 123篇 |
2017年 | 123篇 |
2016年 | 133篇 |
2015年 | 131篇 |
2014年 | 174篇 |
2013年 | 219篇 |
2012年 | 357篇 |
2011年 | 386篇 |
2010年 | 240篇 |
2009年 | 225篇 |
2008年 | 318篇 |
2007年 | 375篇 |
2006年 | 364篇 |
2005年 | 317篇 |
2004年 | 346篇 |
2003年 | 299篇 |
2002年 | 299篇 |
2001年 | 243篇 |
2000年 | 221篇 |
1999年 | 230篇 |
1998年 | 79篇 |
1997年 | 59篇 |
1996年 | 63篇 |
1995年 | 53篇 |
1994年 | 58篇 |
1993年 | 43篇 |
1992年 | 171篇 |
1991年 | 143篇 |
1990年 | 152篇 |
1989年 | 130篇 |
1988年 | 88篇 |
1987年 | 76篇 |
1986年 | 58篇 |
1985年 | 63篇 |
1984年 | 44篇 |
1983年 | 39篇 |
1982年 | 20篇 |
1979年 | 42篇 |
1978年 | 25篇 |
1975年 | 18篇 |
1973年 | 25篇 |
1972年 | 30篇 |
1971年 | 27篇 |
1970年 | 28篇 |
1969年 | 27篇 |
排序方式: 共有7252条查询结果,搜索用时 15 毫秒
81.
82.
83.
Interaction between fibroblast cells and fluorinated polyimide with nano-modified surface 总被引:2,自引:0,他引:2
Nagaoka S Ashiba K Okuyama Y Kawakami H 《The International journal of artificial organs》2003,26(4):339-345
In this study, we investigated the effect of surface nano-modification of aromatic fluorinated polyimide (6FDA-6FAP) derived from 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2'-bis (4-aminophenyl) hexafluoropropane (6FAP) on the interaction with proteins and cells. The surface of 6FDA-6FAP was modified by surface-rubbing showed nano-ordered stripes along the rubbing direction. The rat fibroblast FR cells formed multicellular spheroids with high cell density on the rubbed surface then expressed excellent collagen production similarly in vivo, while on the non-modified surface the cells formed two-dimensional monolayers and the collagen production was negligible. The modulation of cell function by the surface nano-modification along with surface micro-modification may be one of the most important considerations during the design and manufacture of novel biochips or tissue engineering materials. 相似文献
84.
Osamu Tadokoro Vaska Radunovic Katsuhiro Inoue 《Anatomical record (Hoboken, N.J. : 2007)》2008,291(3):242-253
It has been shown that human and cat epithelial cell rests of Malassez (ERM) consist of heterogeneous cell populations. Immunohistochemical and immunoelectron microscopic analyses have verified the presence of neuroendocrine and Merkel‐like cells in both of these epithelia. During experimental orthodontic tooth movement, immunocompetent cells have also been found in the vicinity of ERM in rat periodontal ligament (PDL), but have not been characterized in normal rat PDL. The aim of this study was to investigate the presence and distribution of MHC class II antigen presenting cells by using OX6 antibody in ERM of rat molars by light and transmission electron microscopy. Immunohistochemical and immunoelectron microscopic observations of rat maxillary molars confirmed the presence of OX6‐positive cells in contact with ERM. Some immunopositive cytoplasmic processes containing vesicles interdigitated with cells of the Malassez epithelial clusters. Based on these findings it can be concluded that immunocompetent cells are localized close to Malassez epithelial clusters in normal rat PDL. Furthermore, the ultrastructural evidences indicate a possible interaction between the epithelial and immunocompent cells and suggest morphological and functional properties for ERM. Anat Rec, 291:242–253, 2008. © 2008 Wiley‐Liss, Inc. 相似文献
85.
Stimulatory effect of CD5 antibody on B cells from patients with rheumatoid arthritis 总被引:3,自引:0,他引:3
M Hara A Kitani T Hirose K Norioka M Harigai K Suzuki H Tabata M Kawakami M Kawagoe H Nakamura 《Clinical immunology and immunopathology》1988,49(2):223-230
In order to clarify the role of CD5 antigen on B cell in autoimmunity, we examined B cells from patients with rheumatoid arthritis (RA). The percentages of CD5 positive B cells were increased in peripheral blood from RA compared with normal. Normal and RA B cells were stimulated with two kinds of monoclonal antibodies to CD5 (Leu-1, SL-1) which recognize different epitopes. RA B cells proliferated and secreted IgM by CD5 antibody stimulation in combination with IL-1. Our observations imply that CD5 positive B cells in RA are in their differentiation stage and that CD5 antigen might be one of the triggers to activate CD5 positive B cells in vivo to produce autoantibody. 相似文献
86.
Katsuhiro Komase Takeshi Haga Yasuhiro Yoshikawa Takeshi A. Sato Kazuya Yamanouchi 《Virus genes》1990,4(2):163-172
The full-length cDNA corresponding to the mRNA for the hemagglutinin (H) protein of the Yamagata-1 strain of the subacute sclerosing panencephalitis (SSPE) virus was cloned and the nucleotide sequence was determined. The mRNA corresponding to the H protein was composed of 1952 nucleotides and contained a single large open reading frame, which encoded 620 amino acids with a predicted molecular weight of 69,723. This cDNA clone expressed the H protein in Cos 7 cells, and the transfected cells showed hemadsorption. The nucleotide and amino-acid sequence homology with the Edmonston strain of MV were 98.0% and 96.6%, respectively. The deduced amino acid sequence had a single hydrophobic domain near the N-terminus that was long enough to serve as an anchor in the membrane. Five potential glycosylation sites were found on the H protein at identical positions as in the H protein of MV. Cysteine and proline were located at almost identical positions as those of the H protein of MV. In addition, monoclonal antibody study revealed that three epitopes, including the domains that were involved in the biological activities of the H protein of MV, were conserved on the Yamagata-1 strain. These results suggested that the H protein of the Yamagata-1 strain of defective SSPE virus is structurally and functionally similar to that of the Edmonston strain of MV. 相似文献
87.
Toshiyuki Uryu Katsuhiro Ito Ken-Ichi Kobayashi Kei Matsuzaki 《Macromolecular chemistry and physics.》1979,180(6):1509-1519
In order to elucidate the catalytic behavior of phosphorus pentafluoride in the polymerization of anhydro sugars, 13P and 19F NMR spectra were measured on a reaction mixture of 1,6-anhydro-2,3,4-tri-O-benzyl-β-D -glucopyranose (LGTBE) and PF5 with different mole ratios in a temperature range of ?40 to ?80°C. In the 31P NMR spectrum measured at low temperatures, there was a total of 16 peaks, which consisted of a broad quintet, a septet, and a sharp quartet, being assigned to the PF4O-group, to PF, and to POF3, respectively. These fluoro compounds were also determined by the 19F NMR spectrum of the reaction mixture. The concentration of PF ions was found to correspond to that of oxonium ions, which are assumed to be actual propagating species, by determining both the concentration of PF from 19F NMR spectrum and the degree of polymerization of 2,3,4-tri-O-benzyl-α-D -glucopyranan obtained. Formation of the PF5: LGTBE complex was observed from the 31P NMR spectrum of the polymerization system at ?80°C, which exhibits a broad sextet as well as absorptions due to POF3, PF4O–, and PF. To confirm the PF5:LGTBE complex, the NMR measurement of the PF5: tetrahydropyran complex was carried out. A polymerization mechanism of LGTBE by PF5 catalyst is discussed on the basis of the NMR measurement of the polymerization system. 相似文献
88.
We examined the effects of anteroposterior movement of a sled on human upright standing. Each of six healthy men stood on the platform of a sled in the dark. The sinusoidal acceleration was provided, from 0.02 to 0.04 G, followed by 0.06 and 0.08 G, at a stroke length from 6 to 10 m and then to 14 m. Low acceleration (0.02 and 0.04 G) induced body sway, pivoting on the ankle joint. High acceleration (0.06 and 0.08 G) increased body sway, but the head-neck joint remained locked upright. The electromyographic recordings of the lower leg muscles revealed continuous tonic EMG activities of the gastrocnemius and tibialis anterior muscles at acceleration of 0.02 and 0.04 G, while reciprocal activation was observed at 0.06 and 0.08 G. During head movement, the neck muscles were slightly activated tonically at acceleration of 0.02 and 0.04 G, but they were markedly and tonically activated at 0.06 and 0.08 G. We speculate that the sled oscillation caused body sway in proportion to the acceleration, with the ankle joint playing a principal role. Analysis of neck movement also revealed that the head was held in a fixed upright position, indicating that the vestibulocollic reflex might tonically activate the neck muscles. 相似文献
89.
Kai Aoki Takuji Suzuki Fang Hui Takuro Nakano Koki Yanazawa Masato Yonamine Shinichiro Fujita Takehito Sugasawa Yasuko Yoshida Naomi Omi Yasushi Kawakami Kazuhiro Takekoshi 《Nutrients》2021,13(5)
The effects of exercise on nutrient digestion and absorption in the intestinal tract are not well understood. A few studies have reported that exercise training increases the expression of molecules involved in carbohydrate digestion and absorption. Exercise was also shown to increase the blood concentration of glucagon-like peptide-2 (GLP-2), which regulates carbohydrate digestion and absorption in the small intestine. Therefore, we investigated the effects of exercise on the expression of molecules involved in intestinal digestion and absorption, including GLP-2. Six-week-old male mice were divided into a sedentary (SED) and low-intensity exercise (LEx) group. LEx mice were required to run on a treadmill (12.5 m/min, 1 h), whereas SED mice rested. All mice were euthanized 1 h after exercise or rest, and plasma, jejunum, ileum, and colon samples were collected, followed by analysis via IHC, EIA, and immunoblotting. The levels of plasma GLP-2 and the jejunum expression of the GLP-2 receptor, sucrase-isomaltase (SI), and glucose transporter 2 (GLUT2) were higher in LEx mice. Thus, we showed that acute low-intensity exercise affects the expression of molecules involved in intestinal carbohydrate digestion and absorption via GLP-2. Our results suggest that exercise might be beneficial for small intestine function in individuals with intestinal frailty. 相似文献
90.
In analyzing repeated measurements from randomized controlled trials with mixed‐effects models, it is important to carefully examine the conventional normality assumption regarding the random‐effects distribution and its dependence on treatment allocation in order to avoid biased estimation and correctly interpret the estimated random‐effects distribution. In this article, we propose the use of a gradient function method in modeling with the different random‐effects distributions depending on the treatment allocation. This method can be effective for considering in advance whether a proper fit requires a model that allows dependence of the random‐effects distribution on covariates, or for finding the subpopulations in the random effects. 相似文献