全文获取类型
收费全文 | 2100篇 |
免费 | 124篇 |
专业分类
2224篇 |
出版年
2023年 | 18篇 |
2022年 | 44篇 |
2021年 | 71篇 |
2020年 | 45篇 |
2019年 | 54篇 |
2018年 | 78篇 |
2017年 | 67篇 |
2016年 | 81篇 |
2015年 | 111篇 |
2014年 | 140篇 |
2013年 | 128篇 |
2012年 | 152篇 |
2011年 | 139篇 |
2010年 | 100篇 |
2009年 | 74篇 |
2008年 | 116篇 |
2007年 | 93篇 |
2006年 | 85篇 |
2005年 | 96篇 |
2004年 | 67篇 |
2003年 | 73篇 |
2002年 | 51篇 |
2001年 | 50篇 |
2000年 | 46篇 |
1999年 | 35篇 |
1998年 | 20篇 |
1997年 | 15篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 4篇 |
1987年 | 11篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1969年 | 3篇 |
1962年 | 2篇 |
排序方式: 共有2224条查询结果,搜索用时 15 毫秒
991.
Torriceli Souza Thé Renata Siqueira Portella Marcos Lázaro Guerreiro Sonia Gumes Andrade 《Memórias do Instituto Oswaldo Cruz》2013,108(6):691-698
Acute infection with Trypanosoma cruzi results in intense
myocarditis, which progresses to a chronic, asymptomatic indeterminate form. The
evolution toward this chronic cardiac form occurs in approximately 30% of all
cases of T. cruzi infection. Suppression of delayed type
hypersensitivity (DTH) has been proposed as a potential explanation of the
indeterminate form. We investigated the effect of cyclophosphamide (CYCL)
treatment on the regulatory mechanism of DTH and the participation of heart
interstitial dendritic cells (IDCs) in this process using BALB/c mice
chronically infected with T. cruzi. One group was treated with
CYCL (20 mg/kg body weight) for one month. A DTH skin test was performed by
intradermal injection of T. cruzi antigen (3 mg/mL) in the
hind-footpad and measured the skin thickness after 24 h, 48 h and 72 h. The skin
test revealed increased thickness in antigen-injected footpads, which was more
evident in the mice treated with CYCL than in those mice that did not receive
treatment. The thickened regions were characterised by perivascular infiltrates
and areas of necrosis. Intense lesions of the myocardium were present in
three/16 cases and included large areas of necrosis. Morphometric evaluation of
lymphocytes showed a predominance of TCD8 cells. Heart IDCs were immunolabelled
with specific antibodies (CD11b and CD11c) and T. cruzi
antigens were detected using a specific anti-T. cruzi antibody.
Identification of T. cruzi antigens, sequestered in these cells
using specific anti-T. cruzi antibodies was done, showing a
significant increase in the number of these cells in treated mice. These results
indicate that IDCs participate in the regulatory mechanisms of DTH response to
T. cruzi infection. 相似文献
992.
Meire S. Batistela Dellyana R. Boberg Fabiana A. Andrade Michelli Pecharki Enilze M. de S. F. Ribeiro Iglenir J. Cavalli Rubens S. Lima Cícero A. Urban Lupe Furtado-Alle Ricardo L. R. Souza 《Molecular biology reports》2013,40(12):6613-6617
Lamellipodin protein (Lpd), encoded by the RAPH1 gene, modulates the assembly of actin cytoskeleton through its binding to the Ena/VASPs proteins, and acts in cellular motility and lamelipodial protrusion. The region where RAPH1 gene is located (2q33) is deleted in various types of cancer and the gene expression changes in tumors when compared to normal tissues. Amplifications and deletions of the RAPH1 gene were investigated in breast carcinoma samples, in order to determine the possible relationship of the gene with breast cancer tumorigenesis and lymph node metastasis. RAPH1 gene alterations were determined by relative quantification, standard curve method using Real-time PCR technique in samples of tumor and peripheral blood from 52 patients. Regression and correlation analyses were conducted using gene alterations and clinicopathological data. All samples analyzed were altered, with 63.5 % deletion cases and 36.5 % amplification cases. The logistic regression and correlation analysis with clinicopathological data did not show significant results. The results suggest that although the RAPH1 gene was deleted or amplified in all samples, the Lpd does not seem to play a major role in tumorigenesis of mammary carcinomas and probably other proteins, also involved in the process of cellular motility and metastasis, are acting more effectively for or against the migration of breast tumor cells. 相似文献
993.
Marco Brandalise de Andrade Reinaldo J. Bertini Núcleo de Evolução e Paleobiologia de Vertebrados Departamento de Geologia Aplicada Instituto de Geociências e Ciências Exatas Universidade Estadual Paulista Rio Claro SP Brazil 《Historical Biology》2013,25(2):101-136
Oxygen consumption and ammonia excretion rates were assessed for Terebratulina retusa (L.) held under 3 different regimes of temperature and food availability. These were: 5.6?C, no food (cold, starved); 5.8?C, food present (cold, fed) and 10.7?C food present (warm, fed), which simulated winter conditions, summer conditions and an intermediate treatment. Regressions of oxygen consumption on ash‐free dry weight (AFDW) had slopes which were not significantly different from each other and ranged from 0.953 to 0.999. A common slope of 0.976 was calculated and intercepts based on the common slope used to compare oxygen consumption in each treatment. The rise from cold, starved conditions to warm, fed was 24.5 per cent and this was significant (P < 0.05). Other differences were not significant (P > 0.05) but the cold, fed result was 12.6 per cent higher than cold, starved. Therefore feeding and temperature probably account for equivalent proportions of the rise in metabolism from winter to summer. Ammonia production data were much more variable. Excretion rates of a 50 mg AFDW individual (in ng‐at NH3‐N.h‐1) were as follows: cold, starved: 30.2 cold, fed: 7.1; and warm, fed: 22.9. Oxygen to nitrogen (O:N) ratios reflected these results. Mean O:N ratios were: cold, starved: 8.0; cold, fed: 42.4; warm, fed: 16.3. This shows that the simulated winter group relied heavily on protein to fuel their metabolism, the simulated summer group were less dependent on protein and the intermediate group probably used lipids and carbohydrates to fuel metabolic demands. This possibly reflected a trade off between food supply and increased metabolism from treatment to treatment, demonstrating a flexibility which could have been a contributing factor in the ecological tolerance and geological longevity of some brachiopods. 相似文献
994.
Vildete A. S. Carmo Mônica C. De Oliveira Eduardo C. O. Reis Tânia M. P. D. Guimarães José M. C. Vilela Margareth S. Andrade 《Journal of liposome research》2013,23(1):59-70
Complement activation is an important step in the acceleration of liposome clearance. The anaphylatoxins released following complement activation may motivate a wide variety of physiologic changes. We performed physicochemical characterization and in vitro studies of the interaction of complement system with both noncirculating and long-circulating pH-sensitive and nonpH-sensitive liposomes. The liposomes were characterized by diameter, zeta potential, and atomic force microscopy (AFM). The study of liposome interactions with complement system was conducted using hemolytic assay in rat serum. All liposomes presented a similar mean diameter (between 99.8 and 124.3 nm). The zeta potential was negative in all liposome preparations, except in liposomes modified with aminopoly (ethyleneglycol) 2000-distearoylphosphatidylethanolamine (aPEG2000-DSPE), which presented positive zeta potential. Atomic force microscopy images showed that non–long-circulating pH-sensitive liposomes are prone to vesicles aggregation. Non–pH-sensitive liposomes complement system activates, while pH-sensitive liposomes showed to be poor complement activators in rat serum. 相似文献
995.
996.
Kelly Fernandes de Paula Rodrigues Tiago Eugênio Faria e Arantes Cristina Muccioli João Lins de Andrade Neto Marcelo M. Pinheiro 《Parasitology international》2013,62(3):272-275
TNF-α blockers are associated with reactivation of latent granulomatous infections and almost 6% of the world population has some chorioretinitis (CR) caused by Toxoplasma gondii. Thus, the blockade of TNF-α could reactivate a latent toxoplasmosis infection (LTxI). This study was conducted to evaluate the prevalence and incidence of chronic and active CR related to T. gondii in patients with ankylosing spondylitis (AS). A total of 74 eyes from 37 active AS outpatients starting TNFα blockers were compared with 35 AS patients, matched to age and sex, under conventional therapy in a prospective and controlled trial. All patients underwent serological tests for T. gondii, as well as periodic ophthalmologic examination during 12 months. Active CR was defined if a white, focal retinochoroidal lesion with overlying vitreous inflammation had been found. Retinochoroidal lesions with sharp edges, hyperpigmented borders and atrophic center were defined as CR scars. At baseline, no patient had active CR. From the 144 eyes examined, almost 6% had CR scars and only 2.1% had a typical toxoplasmic CR scar and all of them were negative for HLA-B27. During 12 months of follow-up, no recurrence or new CR were observed. AS patients using TNF-α blockers do not have a higher risk of acute or chronic CR caused by T. gondii. 相似文献
997.
Henrique Andrade R. Fonseca Francisco A. Fonseca Andrea M. Monteiro Henrique T. Bianco Paulo Boschcov Sergio A. Brandão Luiz Juliano Magnus Gidlund Maria C. Izar 《Cell biochemistry and biophysics》2013,67(3):1451-1460
Obesity and hypertension have been recognized as inflammatory diseases capable of activating the immune system, thus contributing to an increased cardiovascular risk. However, the link between adaptive immunity, obesity, and hypertension is poorly understood. We investigated the relationship of the body mass index (BMI) on the inflammatory, vascular, and immune responses in patients with hypertension naïve of anti-hypertensive treatment. Hypertensive patients (N = 88) were divided into three groups: normal weight (NW), overweight (OW), and obese (OB) subjects. Anti-oxidized LDL autoantibodies (anti-oxLDL Abs), anti-ApoB-D peptide (anti-ApoB-D) Abs, interleukin (IL)-8 and IL-10, flow-mediated dilation (FMD) of the brachial artery, and 24-h ambulatory blood pressure monitoring (ABPM) were assessed. OB patients presented lower levels of anti-oxLDL Abs and IL-10, higher levels of IL-8, and impaired FMD, when compared to NW and OW (P < 0.05), without differences between groups regarding anti-ApoB-D Abs. After adjusting for age, systolic and diastolic blood pressure, anti-oxLDL Abs were inversely correlated with BMI and waist circumference (r = ?0.24, P = 0.02 and r = ?0.25, P = 0.02, respectively), whereas ApoB-D correlated with 24-h ABPM (r = 0.22, P = 0.05 for systolic, and r = 0.29, P = 0.01 for diastolic blood pressure). Regression analyses showed inverse associations of anti-oxLDL Abs with BMI (β = ?0.05, P = 0.01) and waist circumference (β = ?0.01, P = 0.02); anti-ApoB-D Abs were associated with systolic and diastolic 24-h ABPM (β = 0.96, P = 0.04; β = 1.02, P = 0.005, for systolic and diastolic 24-h ABPM, respectively). Among hypertensive patients, obesity modulates the immune and inflammatory milieu, determining an unfavorable balance of cytokines and reduction in titers of anti-oxLDL Abs. Twenty-four hour ABPM is associated with titers of anti-ApoB-D Abs. 相似文献
998.
J. Janatova R. E. Crandall J. D. Andrade 《Preparative biochemistry & biotechnology》2013,43(4):405-430
A simple and rapid procedure for characterization of serum albumin samples and for the isolation of fractions from fresh serum or commercial sources has been developed, based on DEAE Sepharose CL-6B ion exchange chromatography. Characterization of the fractions included sulfhydryl analysis, gel electrophoresis, and immunoelectrophoresis. Both analytical and preparative procedures were used. It has been shown that the relative content of the fractions varies from individual to individual. It has also been shown that certain fractions found in commercial preparations are artifacts which should be removed before performing serious studies with serum albumin. 相似文献
999.
Aguiar DP Pontes B Mendes FA Andrade LR Viana NB Abreu JG 《Biochemical and biophysical research communications》2011,(4):582-587
Connective tissue growth factor (CTGF/CCN2) is a protein of the CCN family that modulates cell–ECM interactions in a variety of cell types. In this study, we investigated the chemotactic and adhesive properties of CCN2 protein in embryonic teratocarcinoma P19 cells. Initially, P19 cells were attracted to CCN2-coated agarose beads. In Boyden chamber experiments, CCN2-containing medium induced a threefold greater migration of P19 cells. CCN2 adhesion properties were studied by using optical tweezers. The specific adhesion times of P19 cells to polystyrene beads coated with laminin, fibronectin, CCN2 and bovine serum albumin were 1.8 ± 0.5s, 2.7 ± 0.4s, 10 ± 2s and 13 ± 2s, respectively, revealing an unexpectedly low adhesive capacity of CCN2 protein for P19 cells. In conclusion, our findings support the chemoattractive role of CCN2 for P19 cells, but not its adhesive role when compared to laminin or fibronectin. 相似文献
1000.