全文获取类型
收费全文 | 1726篇 |
免费 | 89篇 |
国内免费 | 1篇 |
专业分类
1816篇 |
出版年
2024年 | 5篇 |
2023年 | 21篇 |
2022年 | 31篇 |
2021年 | 62篇 |
2020年 | 34篇 |
2019年 | 36篇 |
2018年 | 48篇 |
2017年 | 40篇 |
2016年 | 56篇 |
2015年 | 86篇 |
2014年 | 102篇 |
2013年 | 115篇 |
2012年 | 168篇 |
2011年 | 149篇 |
2010年 | 88篇 |
2009年 | 58篇 |
2008年 | 101篇 |
2007年 | 88篇 |
2006年 | 75篇 |
2005年 | 81篇 |
2004年 | 72篇 |
2003年 | 75篇 |
2002年 | 57篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 2篇 |
排序方式: 共有1816条查询结果,搜索用时 15 毫秒
991.
Greve B Vijayakrishnan L Kubal A Sobel RA Peterson LB Wicker LS Kuchroo VK 《Journal of immunology (Baltimore, Md. : 1950)》2004,173(1):157-163
Linkage analysis and congenic mapping in NOD mice have identified a susceptibility locus for type 1 diabetes, Idd5.1 on mouse chromosome 1, which includes the Ctla4 and Icos genes. Besides type 1 diabetes, numerous autoimmune diseases have been mapped to a syntenic region on human chromosome 2q33. In this study we determined how the costimulatory molecules encoded by these genes contribute to the immunopathogenesis of experimental autoimmune encephalomyelitis (EAE). When we compared levels of expression of costimulatory molecules on T cells, we found higher ICOS and lower full-length CTLA-4 expression on activated NOD T cells compared with C57BL/6 (B6) and C57BL/10 (B10) T cells. Using NOD.B10 Idd5 congenic strains, we determined that a 2.1-Mb region controls the observed expression differences of ICOS. Although Idd5.1 congenic mice are resistant to diabetes, we found them more susceptible to myelin oligodendrocyte glycoprotein 35-55-induced EAE compared with NOD mice. Our data demonstrate that higher ICOS expression correlates with more IL-10 production by NOD-derived T cells, and this may be responsible for the less severe EAE in NOD mice compared with Idd5.1 congenic mice. Paradoxically, alleles at the Idd5.1 locus have opposite effects on two autoimmune diseases, diabetes and EAE. This may reflect differential roles for costimulatory pathways in inducing autoimmune responses depending upon the origin (tissue) of the target Ag. 相似文献
992.
Bahekar RH Jain MR Jadav PA Prajapati VM Patel DN Gupta AA Sharma A Tom R Bandyopadhya D Modi H Patel PR 《Bioorganic & medicinal chemistry》2007,15(21):6782-6795
In the present investigation, two series of 2,5-disubstituted-3-imidazol-2-yl-pyrrolo[2,3-b]pyridines (2a-l) and thieno[2,3-b]pyridines (3a-l) were designed as analogs of BL 11282 (1). The in vitro glucose dependent insulinotropic activity of all the test compounds was evaluated using RIN5F cell based assay and all the test compounds showed glucose and concentration dependent insulin secretion. The in vivo antidiabetic activities of most potent compounds from each series (2c and 3c) were assessed in C57BL/6J mice. Compounds 2c and 3c showed dose dependent insulin secretion and significant glucose reduction in vivo. In general, compounds 2c and 3c were found to be equipotent at all the three different doses selected and with respect to BL 11282, both the test compounds were found to be more potent, at all the time points. 相似文献
993.
994.
Selenium has been reported to reduce the risk for heart diseases and cancer. We examined the association of sex, age, geographical location, serum cotinine concentrations, a measure of smoking intensity, and alcohol consumption with serum selenium concentrations in the third National Health and Nutrition Examination Survey (NHANES III), 1988-1994. Study sample consisted of 14,619 apparently healthy individuals (male: 7,102; female: 7,517) aged 14 to >90 years. Sex, age, geographical location, serum cotinine concentrations, and alcohol consumption significantly influenced serum selenium concentrations (P < 0.05). The mean (+/- standard error) serum selenium concentration in men (124.5 +/- 0.20 ng/mL) was significantly higher than in women (122.0 +/- 0.20 ng/mL) (P < 0.0001). Men in the 31-50 y age group had the highest mean serum selenium concentration. In the same age group, women had the lowest mean serum selenium concentration. In both sexes, participants living in the Midwest and West had significantly higher serum selenium concentrations than those living in South and Northeast geographical locations. Serum cotinine was negatively associated with serum selenium concentrations in both men (beta = -0.0108; P < 0.0001 for trend) and women (beta = -0.0097; P < 0.0001 for trend). Alcohol consumption is positively associated with serum selenium in women (beta = 0.0462; P = 0.0044 for trend) but not in men (beta = 0.0015; P = 0.8496 for trend). Although, sex, age, geographical location, smoking, and alcohol intake influenced serum selenium concentrations, clinically low serum selenium concentrations are not common in the USA. 相似文献
995.
Muneendra Kumar Harjit Kaur Amrish Kumar Tyagi Neelam J. Kewalramani Veena Mani Rijusmita Sarma Deka Vijay Kumar Sharma Gulab Chandra Ajay Kumar Dang 《Biological trace element research》2013,155(3):352-360
We investigated the effect of chromium (Cr) supplementation on the growth performance, energy metabolites, and hormonal variation in winter-exposed buffalo calves. Twenty-four female buffalo calves were randomly allotted to four dietary treatments (n?=?6) for a period of 120 days. Feeding regimen was the same in all the groups, except the animals in the four respective groups were additionally supplemented with 0.0, 0.5, 1.0, and 1.5 mg of Cr/kg DM in the form of CrCl3.6H2O. Calves were monitored daily for physiological variables and dry matter intake (DMI). Blood samples were collected at fortnightly intervals from each buffalo calves to measure concentrations of hormones (insulin, cortisol, and growth hormone), energy metabolites (glucose and non-esterified fatty acids), and plasma mineral levels. After 120 days of feeding trial, buffalo calves fed with Cr had lower (P?<?0.05) circulating plasma concentrations of glucose, insulin, and cortisol hormones, whereas plasma thyroid hormone and non-esterified fatty acids concentrations were found similar (P?>?0.05) among all the treatments. The results suggested that dietary Cr supplementation influenced plasma Cr levels without affecting the plasma concentrations of other trace minerals. However, physiological variables, nutrient intake, and growth performance of buffalo calves did not differ among all treatments (P?>?005). In summary, the current study showed that supplementation of Cr at the level of 1.0 and 1.5 mg of Cr/kg DMI was more effective in improving glucose utilization by increasing potency of insulin hormone and reducing concentration of cortisol hormone. Results also suggested that supplemental Cr also improves blood plasma Cr levels. 相似文献
996.
Puneet Kumar Pawan K. Rana Himshikha Vijay Kumar Singhal R. C. Gupta 《Protoplasma》2014,251(4):781-795
Despite the presence of intraspecific polyploidy (2x, 4x, 5x and 6x) in Agrimonia eupatoria, origin of these cytotypes has never been addressed adequately. The aim of the present study was to record the original chromosome counts and characterize chromosomal pairing during meiosis and microsporogenesis in the 5x cytotype, and discussing the hypothesis regarding the possible origin of polyploid cytotypes (4x, 5x and 6x) in the species. The geographical distribution pattern of cytotypes in the Indian Himalayas and elsewhere has also been analyzed. The present meiotic analysis revealed three chromosomes counts, the tetraploid (2n?=?4x?=?56), the pentaploid (2n?=?5x?=?70) and the hexaploid (2n?=?6x?=?84) cytotypes based on x?=?14. Meiotic course was perfectly normal in the 4x and 6x cytotypes resulting into high pollen fertility (94–100 %). Meiotic course in the imbalanced 5x cytotype has been found to be irregular characterized by the presence of high frequency of univalents at diakinesis and metaphase-I. Abnormal meiotic course contributed towards high pollen sterility (74–88 %). Even the apparently fertile/stained pollen grains were of irregular shape and of heterogeneous sizes. Meiotic behaviour of the 5x cytotype is like typical of allopolyploid. Individuals of 5x cytotype did not produce seeds and propagate vegetatively (root suckers) while 4x and 6x cytotypes exploited sexual (seeds) as well as vegetative means for propagation. Chromosomal pairing in pentaploid cytotype is like typical of an allopolyploid and we assume that it might have originated owing to natural inter-cytotype hybridization between 4x and 6x cytotypes in a mixed population. Analysis of geographical distribution pattern of cytotypes shows that Indian Himalayas represent the most cytotype-diverse region for A. eupatoria with the existence of all the four cytotypes (2x, 4x, 5x, 6x). This shows the dynamic nature of the species at chromosomal level in this part of the world. 相似文献
997.
Durkeshwari Anbalagan Gracemary Yap Yi Yuan Vijay K. Pandey Wai Hoe Lau Suruchi Arora Pradeep Bist Justin S. B. Wong Gautam Sethi Peter M. Nissom Peter E. Lobie Lina H. K. Lim 《PloS one》2014,9(12)
Annexin 1 (ANXA1) is an endogenous anti-inflammatory protein implicated in cancer. ANXA1 was previously shown to be regulated by hsa-miR-196a. However, whether ANXA1 itself regulates microRNA (miR) expression is unknown. Therefore, we investigated the regulation of miR by ANXA1 in MCF7 breast cancer cells. MCF7-EV (Empty vector) and MCF7-V5 (ANXA1-V5 expressing cells) were subjected to a miR microarray. Microarray analysis revealed a number of miRNAs which were dysregulated in MCF7-V5 cells. 2 novel miRNAs (miR562 and miR26b*) were validated, cloned and functionally characterized. As ANXA1 constitutively activates NF-κB activity to modulate breast cancer metastasis, we found that miR26b* and miR562 directly targeted the canonical NF-κB pathway by targeting the 3′ UTR and inhibiting expression of Rel A (p65) and NF-κB1 (p105) respectively. MiR562 inhibited wound healing, which was reversed when ANXA1 was overexpressed. Overexpression of either miR562 or miR26b* in MCF-7 cells enhanced endothelial tube formation when cocultured with human umbilical cord endothelial cells while conversely, treatment of MCF7 cells with either anti-miR562 or anti-miR26b* inhibited endothelial tube formation after co-culture. Further analysis of miR562 revealed that miR562-transfected cell conditioned media enhances endothelial cell tube formation, indicating that miR562 increased angiogenic secreted factors from MCF-7 breast tumor cells. TNFα was increased upon overexpression of miR562, which was reversed when ANXA1 was co-transfected In conclusion, this data suggests that ANXA1-regulated miR26b* and miR562 may play a role in wound healing and tumor-induced endothelial cell tube formation by targeting NF-κB expression and point towards a potential therapeutic target for breast cancer. 相似文献
998.
Viral capsids are composed of multiple copies of one or a few chemically distinct capsid proteins and are mostly stabilized by inter subunit protein-protein interactions. There have been efforts to identify and analyze these protein-protein interactions, in terms of their extent and similarity, between the subunit interfaces related by quasi- and icosahedral symmetry. Here, we describe a new method to map quaternary interactions in spherical virus capsids onto polar angle space with respect to the icosahedral symmetry axes using azimuthal orthographic diagrams. This approach enables one to map the nonredundant interactions in a spherical virus capsid, irrespective of its size or triangulation number (T), onto the reference icosahedral asymmetric unit space. The resultant diagrams represent characteristic fingerprints of quaternary interactions of the respective capsids. Hence, they can be used as road maps of the protein-protein interactions to visualize the distribution and the density of the interactions. In addition, unlike the previous studies, the fingerprints of different capsids, when represented in a matrix form, can be compared with one another to quantitatively evaluate the similarity (S-score) in the subunit environments and the associated protein-protein interactions. The S-score selectively distinguishes the similarity, or lack of it, in the locations of the quaternary interactions as opposed to other well-known structural similarity metrics (e.g., RMSD, TM-score). Application of this method on a subset of T = 1 and T = 3 capsids suggests that S-score values range between 1 and 0.6 for capsids that belong to the same virus family/genus; 0.6-0.3 for capsids from different families with the same T-number and similar subunit fold; and <0.3 for comparisons of the dissimilar capsids that display different quaternary architectures (T-numbers). Finally, the sequence conserved interface residues within a virus family, whose spatial locations were also conserved have been hypothesized as the essential residues for self-assembly of the member virus capsids. 相似文献
999.
Mahendra B. Bhalerao Sambhaji T. Dhumal Amarsinh R. Deshmukh Laxman U. Nawale Vijay Khedkar Dhiman Sarkar Ramrao A. Mane 《Bioorganic & medicinal chemistry letters》2017,27(2):288-294
New bithiazolyl hydrazones (6a–l) have been first time synthesized by carrying novel one pot cyclocondensation of 5-acyl thiazoles (1a–b), thiosemicarbazide (2) and substituted phenacyl chlorides (4a–f) in freshly prepared ionic liquid, diisopropyl ethyl ammonium acetate (DIPEAc) at room temperature. The newly synthesized compounds have been evaluated for their antitubercular activity and the compounds 3b, 6a, 6b, 6d, 6e, 6f, 6g, and 6l have displayed noticeable antitubercular activity compared to Rifampicin with tolerable cytotoxicity. All these compounds were also screened for their antibacterial activity and found that, compounds 6j and 6k have exhibited a very good antibacterial activity. Molecular docking study has shown better harmony with the evaluation trend shown by these compounds under in vitro antitubercular screening. 相似文献
1000.
Carrier Y Yuan J Kuchroo VK Weiner HL 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(1):179-185
TGF-beta has been shown to be critical in the generation of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs). Because Th3 cells produce large amounts of TGF-beta, we asked whether induction of Th3 cells in the periphery was a mechanism by which CD4(+)CD25(+) Tregs were induced in the peripheral immune compartment. To address this issue, we generated a TGF-beta1-transgenic (Tg) mouse in which TGF-beta is linked to the IL-2 promoter and T cells transiently overexpress TGF-beta upon TCR stimulation but produce little or no IL-2, IL-4, IL-10, IL-13, or IFN-gamma. Naive TGF-beta-Tg mice are phenotypically normal with comparable numbers of lymphocytes and thymic-derived Tregs. We found that repeated antigenic stimulation of pathogenic myelin oligodendrocyte glycoprotein (MOG)-specific CD4(+)CD25(-) T cells from TGF-beta Tg mice crossed to MOG TCR-Tg mice induced Foxp3 expression in both CD25(+) and CD25(-) populations. Both CD25 subsets were anergic and had potent suppressive properties in vitro and in vivo. Furthermore, adoptive transfer of these induced regulatory CD25(+/-) T cells suppressed experimental autoimmune encephalomyelitis when administrated before disease induction or during ongoing experimental autoimmune encephalomyelitis. The suppressive effect of TGF-beta on T cell responses was due to the induction of Tregs and not to the direct inhibition of cell proliferation. The differentiation of Th3 cells in vitro was TGF-beta dependent as anti-TGF-beta abrogated their development. Thus, Ag-specific TGF-beta-producing Th3 cells play a crucial role in inducing and maintaining peripheral tolerance by driving the differentiation of Ag-specific Foxp3(+) regulatory cells in the periphery. 相似文献