首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   624篇
  免费   30篇
  2023年   8篇
  2022年   6篇
  2021年   24篇
  2020年   15篇
  2019年   14篇
  2018年   23篇
  2017年   12篇
  2016年   29篇
  2015年   41篇
  2014年   47篇
  2013年   37篇
  2012年   56篇
  2011年   50篇
  2010年   29篇
  2009年   17篇
  2008年   28篇
  2007年   27篇
  2006年   18篇
  2005年   19篇
  2004年   21篇
  2003年   20篇
  2002年   14篇
  2001年   8篇
  1999年   6篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1994年   3篇
  1993年   2篇
  1992年   4篇
  1991年   3篇
  1990年   6篇
  1989年   5篇
  1988年   3篇
  1987年   2篇
  1986年   3篇
  1984年   5篇
  1983年   2篇
  1981年   5篇
  1979年   2篇
  1978年   3篇
  1977年   2篇
  1976年   3篇
  1974年   3篇
  1973年   2篇
  1972年   2篇
  1970年   3篇
  1968年   2篇
  1967年   2篇
  1966年   4篇
排序方式: 共有654条查询结果,搜索用时 31 毫秒
91.
92.
93.
The efficacy of cancer chemotherapeutics is limited by side effects resulting from narrow therapeutic windows between the anticancer activity of a drug and its cytotoxicity. Thus identification of small molecules that can selectively target cancer cells has gained major interest. Cancer cells under stress utilize the Unfolded protein response (UPR) as an effective cell adaptation mechanism. The purpose of the UPR is to balance the ER folding environment and calcium homeostasis under stress. If ER stress is prolonged, tumor cells undergo apoptosis. In the present study we demonstrated an 3,3′-(Arylmethylene)-bis-1H-indole (AMBI) derivative 3,3′-[(4-Methoxyphenyl) methylene]-bis-(5-bromo-1H-indole), named as Mephebrindole (MPB) as an effective anti-cancer agent in breast cancer cells. MPB disrupted calcium homeostasis in MCF7 cells which triggered ER stress development. Detailed evaluations revealed that mephebrindole by activating p38MAPK also regulated GRP78 and eIF2α/ATF4 downstream to promote apoptosis. Studies extended to in vivo allograft mice models revalidated its anti-carcinogenic property thus highlighting the role of MPB as an improved chemotherapeutic option.  相似文献   
94.
Comparative studies of the electrochemical oxidation of reduced nicotinamide coenzyme (NADH) at the surfaces of chemically modified graphite paste electrodes (CMEs) are reported. Three different electroactive materials, tetracyanoquinodimethane (TCNQ), tetrathiafulvalene (TTF), and dimethyl ferrocene (dmFc), were used to construct three different chemically modified paste electrodes. The oxidation of NADH was examined on the basis of cyclic voltammetric measurements. The results show that all three mediators (TCNQ, TTF, and dmFc) behave as efficient mediators of the oxidation of NADH. The typical response curves of NADH at the CMEs surfaces are reported. Incorporating alcohol dehydrogenase and electroactive materials (TCNQ, TTF, and dmFc) within the graphite paste electrodes has led to the development of ethanol biosensors. Typical response curves for the ethanol analysis are reported. Comparative studies on the mediated electrochemical responses of the biosensors to ethanol are discussed.  相似文献   
95.
96.
Tomato is considered as one of the most important sources of nutrients such as lycopene, β-carotene, flavonoids, ascorbic acid (vitamin C) and hydroxyl-cinnamic acid derivatives. The quality and quantity of nutrients in tomato fruits were decreased during the severe infection of Alternaria alternata. The present study deals with the estimation of lycopene, β-carotene, phenolic and ascorbic acid content in tomato fruits which were infected with A. alternata and its toxins such as tenuazonic acid (TeA), alternariol (AOH) and alternariol monomethyl ether (AME). The lycopene, β-carotene, ascorbic acid and phenolic content were found lowest in pathogen-infected fruits i.e. (0.66 ± 0.03 mg/g), (0.14 ± 0.01 mg/g), (1.89 ± 0.2 mg/g) and (0.58 ± 0.05 mg/g), respectively, followed by toxins-treated samples as compared to the control. The results concluded that A. alternata mostly affects the nutritional values of tomato fruits due to the combined effect of the toxins.  相似文献   
97.
Trichoderma spp. are well-known biological agents that have significant antagonistic activity against several plant pathogenic fungi. In the present study, Trichoderma spp. were tested in vitro for their antagonistic activity against different spp. of Fusarium and Alternaria viz. Alternaria alternata, A. brassicae, A. solani, Fusarium oxysporum and F. solani using dual plate assay and by the production of volatile and non-volatile compounds. The results obtained revealed that Trichoderma harzianum and T. viride effectively inhibited the growth and spore production of different spp. of Fusarium and Alternaria. The highest growth inhibition was found in A. alternata 62.50% and 60.00% by non-volatile compounds of T. harzianum and T. viride, respectively. Similarly, the volatile compounds inhibit the maximum growth of A. alternata 40.00% and 35.00% by T. harzianum and T. viride, respectively. Volatile and non-volatile compounds of Trichoderma spp. were analysed by GC-MS technique and the properties of distinguished compounds showed antifungal, antimicrobial and antibiotic activities. Volatile compounds of T. harzianum and T. viride showed highest percent abundance for glacial acetic acid (45.32%) and propyl-benzene (41.75%), respectively. In case of non-volatile compounds, T. harzianum and T. viride showed D-Glucose, 6-O-α-D-galactopyranosyl- (38.45%) and 17-Octadecynoic acid (36.23%), respectively. The results of present study confirmed that T. harzianum can be used as a promising biological control agent against Alternaria and Fusarium spp. that cause diseases in various vegetables and crops.  相似文献   
98.
The present study was designed to synthesize the bioactive molecule 2,2-bis(2,4-dinitrophenyl)-2-(phosphonatomethylamino)acetate (1), having excellent applications in the field of plant protection as a herbicide. Structure of newly synthesized molecule 1 was confirmed by using the elemental analysis, mass spectrometric, NMR, UV-visible, and FTIR spectroscopic techniques. To obtain better structural insights of molecule 1, 3D molecular modeling was performed using the GAMESS programme. Microbial activities of 1 were checked against the pathogenic strains Aspergillus fumigatus (NCIM 902) and Salmonella typhimurium (NCIM 2501). Molecule 1 has shown excellent activities against fungal strain A. fumigates (35 μg/l) and bacterial strain S. typhimurium (25 μg/l). To check the medicinal significance of molecule 1, interactions with bovine serum albumin (BSA) protein were checked. The calculated value of binding constant of molecule 1–BSA complex was 1.4 × 106 M?1, which were similar to most effective drugs like salicylic acid. More significantly, as compared to herbicide glyphosate, molecule 1 has exhibited excellent herbicidal activities, in pre- and post-experiments on three weeds; barnyard grass (Echinochloa Crus), red spranglitop (Leptochloa filiformis), and yellow nuts (Cyperus Esculenfus). Further, effects of molecule 1 on plant growth-promoting rhizobacterial (PGPR) strains were checked. More interestingly, as compared to glyphosate, molecule 1 has shown least adverse effects on soil PGPR strains including the Rhizobium leguminosarum (NCIM 2749), Pseudomonas fluorescens (NCIM 5096), and Pseudomonas putida (NCIM 2847).  相似文献   
99.
The high level expression and purification of rat monoamine oxidase B (rMAOB) in the methylotrophic yeast Pichia pastoris is reported. Nearly 100 mg of purified rMAOB is obtained from 130 g (wet weight) of cells (0.5 L of culture). The MALDI-TOF mass spectrum of the purified protein shows a single species with a molecular mass of 59.228 ± 0.064 kDa, which agrees with the calculated molecular weight of 59.172 kDa for the rMAOB protein sequence assuming one mole of covalent FAD per mole of the enzyme. Consistent with the MALDI-MS data, purified rMAOB shows a single band near 60 kDa in Coomassie-stained SDS–PAGE gel as well as on Western blot analyses performed using antisera raised against human MAOA and BSA-conjugated FAD. A partial amino acid sequence of the purified protein is confirmed to be that of the wild type rMAOB by in-gel trypsin digestion and MALDI-TOF-MS analyses of the liberated peptide fragments. Steady state kinetic data show that purified rMAOB exhibits a Km(amine) of 176 ± 15 μM and a kcat of 497 ± 83 min−1 for benzylamine oxidation, and a Km(O2) of 170 ± 10 μM. Kinetic parameters obtained for purified rMAOB are compared with those reported earlier for recombinant human liver MAOB expressed in P. pastoris.  相似文献   
100.
OBJECTIVE: This study was undertaken to determine the prevalence and molecular basis of alpha-thalassemia in the Indian population and its implications in genetic counseling and prenatal diagnosis. METHODS: 1253 random samples were screened for hemoglobinopathies. Red cell indices were measured on the Sysmex K 1000 cell counter; HbA2 and HbF levels were quantitated using high performance liquid chromotography (HPLC). Cellulose acetate electrophoresis and isoelectric focusing (IEF) was done to detect the presence of Hb Bart's in cord blood samples. alpha-Globin gene mapping was done using Southern blot hybridization of BamHI and BglII digests. RESULTS: Of the 1253 subjects, 132 had a single alpha-gene deletion (10.5%) while 29 had two alpha-gene deletions (2.31%). Fifteen cases showed the presence of alpha-gene triplication (1.1%). A single case showed the presence of one alpha-gene deletion as well as alpha-gene triplication (-alpha/alphaalphaalpha). Overall, the prevalence of alpha-thalassemia was 12.9%. Region-wise and caste-wise analysis showed the highest prevalence of alpha-thalassemia among the Punjabi population originating from the northern region of India. CONCLUSION: alpha-Thalassemia is by far the commonest hemoglobinopathy in India, but it is not a cause of serious genetic risk is the milder form (-alpha/alphaalpha) of alpha-thalassemia, which is predominant. Knowing the alpha-genotype is useful for genetic counseling for prenatal diagnosis in couples where one of the parents may have reduced indices coupled with a raised RBC count and normal HbA2 levels.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号