全文获取类型
收费全文 | 242篇 |
免费 | 10篇 |
专业分类
252篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 13篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 19篇 |
2013年 | 15篇 |
2012年 | 24篇 |
2011年 | 19篇 |
2010年 | 17篇 |
2009年 | 4篇 |
2008年 | 19篇 |
2007年 | 14篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有252条查询结果,搜索用时 15 毫秒
1.
Summary The occurrence of cells resembling mammalian Langerhans cells in the avian epidermis was studied by ATPase histochemistry, Ia immunoreactivity and electron microscopy. The existence of MHC class II antigen-(Ia) expressing, ATPase-positive dendritic cells, which are ultrastructurally similar to mammalian Langerhans cells except for the absence of Birbeck granules, was demonstrated. These cells may be a basic component of the immune system of birds. 相似文献
2.
Farwa Basit Javaid Akhter Bhat Jiajun Han Yajing Guan Basit Latief Jan Awais Shakoor Saleh Alansi 《Saudi Journal of Biological Sciences》2022,29(5):3918-3928
Rice is the most important crop for the majority of population across the world with sensitive behavior toward heavy metals such as chromium (Cr) in polluted regions. Although, there is no information on the Cr resistance phenotyping in rice. Herein, two different groups of rice cultivars (normal, and hybrid) were used, each group with 14 different rice cultivars. Firstly, seed germination analysis was conducted by evaluating various seed germination indices to identify the rice cultivars with greatest seed germination vigor. Furthermore, exposure of chromium (Cr) toxicity to 28 different rice varieties (NV1-NV14, HV1-HV14) caused noticeable plant biomass reduction. Subsequently, NV2, NV6, NV10, NV12, NV13 (normal type), HV1, HV4, HV8, and HV9 (hybrid types) were pragmatic as moderately sensitive varieties, while NV3, NV4, NV9, and NV14 (normal type), HV3, HV6, HV7, and HV13 were observed as moderately tolerant. Although, NV7, and HV10 were ranked most sensitive cultivars, and NV11, and HV14 were considered as most tolerant varieties as compared to the other rice (both groups) genotypes. Afterward, Cr induced reduction in chlorophyll pigments were significantly lesser in HV14 relative to NV11, NV7, and especially HV10, and as a result HV14 modulated the total soluble sugar level as well as reduced ROS accumulation, and MDA contents production by stimulating the antioxidant defense mechanism conspicuously which further reduced the electrolyte leakage as well. Our outcomes provide support to explore the Cr tolerance mechanism in cereal crops as well as knowledge about rice breeding with increased tolerance against Cr stress. 相似文献
3.
The study compares the 3 years of birth control practice of 1172 women who underwent early menstrual regulation (MR) and 499 others who accepted contraceptives only (nonMR) from an urban clinic in Bangladesh. About 60% of the women in the sample were followed-up and their all-method continuation rate was analyzed by life-table technique. The 3-year overall continuation rate in the MR group (64%) did not differ from that of the nonMR group (62%). In the age groups 25 and over, the continuation rate was higher in the MR group. Among the women who did not desire any more children, the continuation rate in the MR group was significantly higher than that of the nonMR group (80% versus 68%, P0.05). Of women with parity greater than 2, the MR group had significantly higher continuation rates than the nonMR group. The MR group had higher extended use-effectiveness for IUDs, conventional contraceptives (condom and foam), injectables, and oral contraceptives than the nonMR group. These findings indicated effective contraceptive practice following MR for this urban population. Easy availability of a multimethod service after MR seemed to be important in promoting effective contraception. 相似文献
4.
Linda J. Chan John D. Wade Frances Separovic Ross A. D. Bathgate Mohammed Akhter Hossain 《International journal of peptide research and therapeutics》2013,19(1):55-60
H2 relaxin (relaxin) is a member of the insulin–relaxin superfamily and exhibits several non-reproductive functions in addition to its well-known properties as a pregnancy hormone. Over the years, the therapeutic potential of relaxin has been examined for a number of conditions. It is currently in phase III clinical trials for the treatment of acute heart failure. The 53 amino acid peptide hormone consists of two polypeptide chains (A and B) which are cross-linked by two inter-chains and one intra-A chain disulfide bridge. Although its cognate receptor is relaxin family peptide receptor (RXFP) 1, relaxin is also able to cross-react with RXFP2, for which the native ligand is INSL3. The “RXXXRXXI” motif in the B-chain of H2 relaxin is responsible for primary binding to LRR of the RXFP1 receptor (Büllesbach and Schwabe, J Biol Chem 280:14051–14056, 2005). Previous RXFP2 receptor mutation and molecular modelling studies strongly suggest that, in addition to this motif, the Trp-B28 residue in the B-chain is responsible for H2–RXFP2 interaction. To confirm this finding, here we have mutated H2 relaxin in which Trp-B28 was replaced with alanine. The synthetic relaxin analogue was then tested on cells expressing either RXFP1 or 2 to determine the affinity and potency for the respective receptors. Our results confirm that Trp-B28 in the B-chain is crucial for binding and activating RXFP2, but not for RXFP1. 相似文献
5.
Alessia Belgi Ross A. D. Bathgate Geoffrey W. Tregear John D. Wade Mohammed Akhter Hossain 《International journal of peptide research and therapeutics》2013,19(1):71-79
Insulin-like peptide 5 (INSL5) is a two-chain, three-disulfide bonded member of insulin/relaxin superfamily of peptides that includes insulin, insulin-like growth factor I and II (IGFI and IGFII), insulin-like peptide 3, 4, 5 and 6 (INSL3, 4, 5 and 6), relaxin-1 (H1 relaxin), -2 (H2 relaxin) and -3 (H3 relaxin). Although it is expressed in relatively high levels in the gut, its biological function remains unclear. However, recent reports suggest a significant orexigenic action and a role in the regulation of insulin secretion and β-cell homeostasis, which implies that both agonists and antagonists of the peptide may have significant therapeutic applications. Modern solid phase synthesis techniques together with regioselective disulfide bond formation were employed for a preliminary structure–function relationship study of mouse INSL5. Two point mutated analogues, mouse INSL5 A-B(R24A, W25A) and mouse INSL5 A-B(K6A, R14A, Y18A) were chemically prepared, where the residues in the B-chain that may be involved in receptor activation and affinity binding, were respectively mutated. Synthetic mouse INSL5 A-B(R24A, W25A) analogue was inactive on RXFP4, the native receptor for INSL5, suggesting ArgB24 and TrpB25 are probably directly involved in INSL5 receptor activation. Mouse INSL5 A-B(K6A, R14A, Y18A) analogue had both decreased affinity and potency on RXFP4 (pIC50 7.7 ± 0.2, pEC50 7.87 ± 0.18) which indicated that one or more of these residues are critical for the binding to the receptor. 相似文献
6.
Tijjani Salihu Shinkafi Abhinav Kaushik Amena Mahmood Ambrish Kumar Tiwari Mohammad Mumtaz Alam Mymoona Akhter 《Journal of biomolecular structure & dynamics》2020,38(10):2976-2987
AbstractThis study identifies and validates hexokinase type 4 (HK4), an isozyme of hexokinase in the liver and pancreas, as an important target of C2-β-D-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone (βdGT), a xanthone glucoside suggested to have antidiabetic property. In the study, we applied the computational pipeline of molecular docking followed by the molecular dynamics simulations to shortlist potential βdGT protein targets. The analysis of protein dynamics and the binding free energy (ΔG) led us to the identification of HK4 as a key βdGT target, whereby the binding mode and domain dynamics suggested the activator function of βdGT. βdGT bound to the allosteric site of the isozyme ~13?Å away from the substrate (glucose)-binding site. The binding free energy of the ligand-protein complex was energetically feasible (ΔG, –41.61?kcal/mol) and the cleft angle deviation between the two (small and large) domains of HK4 revealed differential HK4 dynamics in response to βdGT binding. 3D structure analysis of the isozyme-ligand complex highlighted the role of Arg63, Glu67 and Lys458 in ligand stabilization and hydrophobic interactions mediated by Tyr214 and Met235. Experimental validation of the results of computational analysis confirmed the activator function of βdGT on HK4. The study has implication in diabetes as βdGT may be used to lower the blood glucose level by activating hepatic and pancreatic hexokinase without the risk of hypoglycemia.Communicated by Ramaswamy H. Sarma 相似文献
7.
Gulwaiz Akhter Aiman Zafar Waseem Khan Mohmmad Jamshed 《Archives Of Phytopathology And Plant Protection》2013,46(7-8):399-407
AbstractAqueous leaf extracts of four commonly growing weeds namely Ageratum conyzoides, Elephantopus scaber, Lantana camara and Xanthium strumarium were used to evaluate their nematicidal activity on second stage juvenile of Meloidogyne incognita race-3. The juveniles were exposed to various concentration of leaf extract namely 250, 500, 1000 and 2000?ppm for 12, 24 and 48?h, respectively. All leaf extracts showed the nematicidal property in concentration and time-dependent manner. The maximum juvenile mortality was recorded in E. scaber throughout the incubation period followed by X. strumarium, L. camara and A. conyzoides. The regression and correlation of regression revealed the best concentration-dependent effect of aqueous leaf extracts on nematode mortality in E. scaber (R2?=?.751) followed by X. strumarium (R2?=?.749), A. conyzoides (R2?=?.687) and L. camara (R2?=?.756). Aqueous leaves extracts of these aforementioned weeds showed nematicidal properties, therefore, may be used as a key component of integrated disease management programme. 相似文献
8.
9.
Cheng-Siang Lee Nur Aishah Mohd Taib Ali Ashrafzadeh Farhana Fadzli Faizah Harun Kartini Rahmat See Mee Hoong Puteri Shafinaz Abdul-Rahman Onn Haji Hashim 《PloS one》2016,11(2)
Heavily glycosylated mucin glycopeptides such as CA 27.29 and CA 15–3 are currently being used as biomarkers for detection and monitoring of breast cancer. However, they are not well detected at the early stages of the cancer. In the present study, perchloric acid (PCA) was used to enhance detection of mucin-type O-glycosylated proteins in the serum in an attempt to identify new biomarkers for early stage breast cancer. Sensitivity and specificity of an earlier developed sandwich enzyme-linked lectin assay were significantly improved with the use of serum PCA isolates. When a pilot case-control study was performed using the serum PCA isolates of normal participants (n = 105) and patients with stage 0 (n = 31) and stage I (n = 48) breast cancer, higher levels of total O-glycosylated proteins in sera of both groups of early stage breast cancer patients compared to the normal control women were demonstrated. Further analysis by gel-based proteomics detected significant inverse altered abundance of proteoglycan 4 and plasma protease C1 inhibitor in both the early stages of breast cancer patients compared to the controls. Our data suggests that the ratio of serum proteoglycan 4 to protease C1 inhibitor may be used for screening of early breast cancer although this requires further validation in clinically representative populations. 相似文献
10.
Role of Arabidopsis AtPI4Kγ3, a type II phosphoinositide 4‐kinase,in abiotic stress responses and floral transition 下载免费PDF全文
Salina Akhter Mohammad N. Uddin In S. Jeong Dae W. Kim Xiao‐Min Liu Jeong D. Bahk 《Plant biotechnology journal》2016,14(1):215-230
Phosphoinositides (PIs) are essential metabolites which are generated by various lipid kinases and rapidly respond to a variety of environmental stimuli in eukaryotes. One of the precursors of important regulatory PIs, phosphatidylinositol (PtdIn) 4‐phosphate, is synthesized by PtdIns 4‐kinases (PI4K). Despite its wide distribution in eukaryotes, its role in plants remains largely unknown. Here, we show that the activity of AtPI4Kγ3 gene, an Arabidopsis (Arabidopsis thaliana) type II PtdIn 4‐kinase, is regulated by DNA demethylation and some abiotic stresses. AtPI4Kγ3 is targeted to the nucleus and selectively bounds to a few PtdIns. It possessed autophosphorylation activity but unexpectedly had no detectable lipid kinase activity. Overexpression of AtPI4Kγ3 revealed enhanced tolerance to high salinity or ABA along with inducible expression of a host of stress‐responsive genes and an optimal accumulation of reactive oxygen species. Furthermore, overexpressed AtPI4Kγ3 augmented the salt tolerance of bzip60 mutants. The ubiquitin‐like domain of AtPI4Kγ3 is demonstrated to be essential for salt stress tolerance. Besides, AtPI4Kγ3‐overexpressed plants showed a late‐flowering phenotype, which was caused by the regulation of some flowering pathway integrators. In all, our results indicate that AtPI4Kγ3 is necessary for reinforcement of plant response to abiotic stresses and delay of the floral transition. 相似文献