全文获取类型
收费全文 | 913篇 |
免费 | 74篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 16篇 |
妇产科学 | 19篇 |
基础医学 | 131篇 |
口腔科学 | 6篇 |
临床医学 | 164篇 |
内科学 | 270篇 |
皮肤病学 | 7篇 |
神经病学 | 75篇 |
特种医学 | 6篇 |
外科学 | 83篇 |
综合类 | 21篇 |
预防医学 | 88篇 |
眼科学 | 2篇 |
药学 | 36篇 |
肿瘤学 | 56篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 17篇 |
2018年 | 16篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 22篇 |
2014年 | 27篇 |
2013年 | 48篇 |
2012年 | 35篇 |
2011年 | 48篇 |
2010年 | 31篇 |
2009年 | 21篇 |
2008年 | 46篇 |
2007年 | 56篇 |
2006年 | 60篇 |
2005年 | 58篇 |
2004年 | 55篇 |
2003年 | 51篇 |
2002年 | 43篇 |
2001年 | 14篇 |
2000年 | 16篇 |
1999年 | 17篇 |
1998年 | 18篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 14篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 6篇 |
1985年 | 25篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1976年 | 6篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有989条查询结果,搜索用时 15 毫秒
1.
2.
Immunization with amyloid-β (Aβ) peptide reduces amyloid load in animal studies and in humans; however clinical trials resulted in the development of a pro-inflammatory cellular response to Aβ. Apoptosis has been employed to stimulate humoral and Th2-biased cellular immune responses. Thus, we sought to investigate whether immunization using a DNA vaccine encoding Aβ in conjunction with an attenuated caspase generates therapeutically effective antibodies. Plasmids encoding Aβ and an attenuated caspase were less effective in reducing amyloid pathology than those encoding Aβ alone. Moreover, use of Aβ with an Arctic mutation (E22G) as an immunogen was less effective than wild-type Aβ in terms of improvements in pathology. Low levels of IgG and IgM were generated in response to immunization with a plasmid encoding wild-type Aβ. These antibodies decreased plaque load by as much as 36 ± 8% and insoluble Aβ42 levels by 56 ± 3%. Clearance of Aβ was most effective when antibodies were directed against N-terminal epitopes of Aβ. Moreover, immunization reduced CAA by as much as 69 ± 12% in TgCRND8 mice. Finally, high-molecular-weight oligomers and Aβ trimers were significantly reduced with immunization. Thus, immunization with a plasmid encoding Aβ alone drives an attenuated immune response that is sufficient to clear amyloid pathology in a mouse model of Alzheimer's disease. 相似文献
3.
4.
Expression of gelatinases within the trabecular bone compartment of ovariectomized and parathyroidectomized adult female rats 总被引:4,自引:0,他引:4
Ovariectomized (ovx) and parathyroidectomized (ptx) rat models of disturbed bone metabolism have been widely used in evaluating bone changes resulting from hormonal depletion, and are characterized by elevated and depressed bone turnover, respectively. We report here the expression of gelatinases extracted from native trabecular bone in these models. Nine-month-old female Sprague-Dawley rats were sacrificed after 3 weeks following ovx or 10 days post ptx to determine the influence of these procedures on the levels of proximal tibial bone tissue gelatinases. Identification and quantitation of these enzymes were performed via gelatin gel zymography of native tissue extracts and laser densitometry of developed gels, respectively. In the ptx model, a reduction in tissue levels of pro- and active-MMP-2 and 45 kDa activated fragment was seen, whereas ovx exhibited significant increases in these enzymes. The MMPs are therefore clearly under the influence of factors known to modulate bone remodeling in vivo. The study of MMP levels directly extracted from bone using these experimental models may assist in developing management regimes for metabolic bone diseases through the use of drugs aimed at controlling turnover. 相似文献
5.
An image processing system for application to studies of the temporal and spatial parameters of movement during swallowing
and speech is described. Image sequences from videotape are digitized for computerized manipulation and analysis in an attempt
to improve on conventional visual inspection. The system is “interactive” or “event-driven”: after executing a function, the
computer waits for guidance from the user who controls the program through keyboard and mouse input, selecting options from
menus and responding to prompts. The analyst alters image clarity by the application of filters and heightens contrast through
video enhancement. A technique called “remapping” reduces head motion and provides uniform spatial scaling. Animated sequences
of images are used, as opposed to frame-by-frame analysis, to preserve temporal context and increase efficiency of measurement.
Low cost off-the-shelf personal computer hardware is used along with original software tailored to the application. 相似文献
6.
I A Cliffe E L Lien H L Mansell K E Steiner R S Todd A C White R M Black 《Journal of medicinal chemistry》1992,35(7):1169-1175
A series of pyrimido[1,2-a]indoles were synthesized and studied for their hypoglycemic activity following oral administration at a standard dose of 100 mg/kg to fed rats. The effect of 10-alkoxyalkyl, 10-alkyl, 10-aryl, and 3,3-dialkyl substitution on the activity of 10-hydroxypyrimido[1,2-a]indoles was investigated. Relative potencies of a number of the most active compounds were defined by three-point dose-response studies. The most potent compounds were those with either 3,3-dimethyl substituents, compounds 21, 22, and 38, or 3,3-spirocyclohexane substituents, compounds 39 and 49. 10-Aminopyrimido[1,2-a]indoles were in general less active than the 10-hydroxy analogues, and potency was further decreased by derivatizing the 10-amino group. The most potent 10-amino derivatives were 57 and 58. 相似文献
7.
We present an 8 year follow-up on a group of children with refractory epileptic seizures who participated in the early 1980s in a controlled group study on the effects of a broad-spectrum behavior modification treatment program on children with refractory epileptic seizures. In the original study, 18 children were divided into three groups: behavior modification group, attention control group, and control group. The purpose was to investigate the effects of a learning-based treatment program superimposed on a regular medical treatment program. Also, the effects of professional attention were evaluated. At the 10 week and 1 year follow-ups, only the group receiving the behavior modification intervention had a significantly reduced rate of seizure index. The present study investigates these same children 8 years later using the same methods of investigation for an additional 10 week period. The results indicate that a significant reduction in seizures was obtained only for the behavior modification group at the 8 year follow-up. 相似文献
8.
9.
Efficiency of the ortho VITROS assay for detection of hepatitis C virus-specific antibodies increased by elimination of supplemental testing of samples with very low sample-to-cutoff ratios
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Oethinger M Mayo DR Falcone J Barua PK Griffith BP 《Journal of clinical microbiology》2005,43(5):2477-2480
The clinical significance of specimens with low sample-to-cutoff (S/Co) ratios in the Ortho VITROS chemiluminescence assay (CIA) for detection of antibodies to hepatitis C virus (HCV) was evaluated. In one study of 482 CIA-reactive samples, none of the 83 samples with S/Co ratios of < 5 was HCV RNA positive. In a subsequent study, 332 samples with S/Co ratios of between 1 and 20 were tested with the recombinant immunoblot assay (RIBA). None of the 163 samples with S/Co ratios of < 5 was RIBA positive, 83% were RIBA negative, and 28 samples (18%) were RIBA indeterminate. HCV RNA and/or clinical evidence of hepatitis was not found in the 27 indeterminate cases examined. These results show that over 99% of samples with very low S/Co ratios (< or = 5) have no evidence of HCV infection. Therefore, we suggest that the HCV antibody testing algorithm for the VITROS assay might be modified to eliminate supplemental testing of samples with very low S/Co ratios. 相似文献
10.
Phuektes P Mansell PD Dyson RS Hooper ND Dick JS Browning GF 《Journal of clinical microbiology》2001,39(4):1460-1466
Pulsed-field gel electrophoresis and antimicrobial sensitivity testing were used as tools to investigate the epidemiology of Streptococcus uberis mastitis in dairy cows. A total of 62 different strains were found among 138 isolates from the four herds investigated, and between 10 and 26 different strains were found in each herd. There was no strain common to all four herds. Identical strains of S. uberis were detected from different quarters of individual cows and from cows within the same herd, suggesting that transmission from quarter to quarter and cow to cow had occurred. Despite the great variation in S. uberis strains, persistent infection with the same strain within a lactation was observed in most cows. Predominant strains were present in two herds. Preliminary investigations could not clarify why these particular strains might predominate, but in one herd there was a significant difference between the prevalence of clinical mastitis in quarters infected with the predominant strain and that in quarters infected with other strains, suggesting the greater virulence of the predominant strain. The wide variety of S. uberis strains found is consistent with an environmental source of S. uberis. However, evidence of direct transmission, the persistence of infection, and the predominance of particular strains in some herds indicate that S. uberis infections are epidemiologically complex and that the relative importance of these factors in the occurrence of mastitis may differ between herds. 相似文献