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71.
Ganguly T Chattoraj P Das M Chanda PK Mandal NC Lee CY Sau S 《Journal of biochemistry and molecular biology》2004,37(6):709-714
The wild-type repressor CI of temperate mycobacteriophage L1 and the temperature-sensitive (ts) repressor CIts391 of a mutant L1 phage, L1cIts391, have been separately overexpressed in E. coli. Both these repressors were observed to specifically bind with the same cognate operator DNA. The operator-binding activity of CIts391 was shown to differ significantly than that of the CI at 32 to 42 degrees C. While 40-95% operator-binding activity was shown to be retained at 35 to 42 degrees C in CI, more than 75% operator-binding activity was lost in CIts391 at 35 to 38 degrees C, although the latter showed only 10% less binding compared to that of the former at 32 degrees C. The CIts391 showed almost no binding at 42 degrees C. An in vivo study showed that the CI repressor inhibited the growth of a clear plaque former mutant of the L1 phage more strongly than that of the CIts391 repressor at both 32 and 42 degrees C. The half-life of the CIts391-operator complex was found to be about 8 times less than that of the CI-operator complex at 32 degrees C. Interestingly, the repressor-operator complexes preformed at 0 degrees C have shown varying degrees of resistance to dissociation at the temperatures which inhibit the formation of these complexes are inhibited. The CI repressor, but not that of CIts391, regains most of the DNA-binding activity on cooling to 32 degrees C after preincubation at 42 to 52 degrees C. All these data suggest that the 131(st) proline residue at the C-terminal half of CI, which changed to leucine in the CIts391, plays a crucial role in binding the L1 repressor to the cognate operator DNA, although the helix-turn-helix DNA-binding motif of the L1 repressor is located at its N-terminal end. 相似文献
72.
Sen P Mukherjee S Bhaumik G Das P Ganguly S Choudhury N Raha S 《Mutation research》2003,529(1-2):87-94
Exposure of Chinese hamster V79 fibroblasts to mild and repetitive H2O2 doses in culture for 15 weeks produced no change in lipid peroxidation status, GSH/GSSG ratio and glutathione peroxidase activity of these cells (VST cells). In contrast, in VST cells catalase levels underwent a prominent increase which could be significantly inhibited and brought down to control levels after treatment with the catalase inhibitor 3-aminotriazole (3-AT). When control (VC) cells were exposed to UV radiation (UVC 5 J/m2) or H2O2 (7.5mM, 15 min), intracellular reactive oxygen species (ROS) levels rose prominently with significant activation of caspase-3. Marked nuclear fragmentation and lower cell viability were also noted in these cells. In contrast, VST cells demonstrated a significantly lower ROS level, an absence of nuclear fragmentation and an unchanged caspase-3 activity after exposure to UVC or H2O2. Cell viability was also significantly better preserved in VST cells than VC cells after UV or H2O2 exposures. Following 3-AT treatment of VST cells, UVC radiation or H2O2 brought about significantly higher elevations in intracellular ROS, increases in caspase-3 activity, significantly lowered cell viability and marked nuclear fragmentation, indicating the involvement of high catalase levels in the cytoprotective effects of repetitive stress. Therefore, upregulation of the antioxidant defense after repetitive oxidative stress imparted a superior ability to cope with subsequent acute stress and escape apoptotic death and loss of viability. 相似文献
73.
Serotonin N-acetyltransferase (AANAT) controls the daily rhythm in melatonin synthesis. When isolated from tissue, AANAT copurifies with isoforms epsilon and zeta of 14-3-3. We have determined the structure of AANAT bound to 14-3-3zeta, an association that is phosphorylation dependent. AANAT is bound in the central channel of the 14-3-3zeta dimer, and is held in place by extensive interactions both with the amphipathic phosphopeptide binding groove of 14-3-3zeta and with other parts of the central channel. Thermodynamic and activity measurements, together with crystallographic analysis, indicate that binding of AANAT by 14-3-3zeta modulates AANAT's activity and affinity for its substrates by stabilizing a region of AANAT involved in substrate binding. 相似文献
74.
AIMS: The influence of carbon-nitrogen and nitrogen-phosphorus ratios of input fertilizers, and that of pond water, on the growth of heterotrophic and phosphate-solubilizing bacteria of water and sediment, was examined in relation to fertilizer mineralization indices using different modes of fertilization through inorganic and organic sources. METHODS AND RESULTS: The first experiment used carbon-nitrogen-phosphorus ratios varying from 12 : 2 : 1 to 151 : 6 : 1, applied at the rate of 0.043 g l(-1) week(-1), whereas in the second ratios varied from 25.6 : 6.2 : 1 to 150 : 12 : 1 applied once at the rate of 3.33 g l(-1). Different fertilizers (cattle dung, poultry droppings, urea, single superphosphate and starch) were mixed in different proportions to achieve the desired carbon-nitrogen-phosphorus ratio. The heterotrophic and phosphate-solubilizing populations were more responsive to an early manuring phase than later, implying that pond fertilization was microbiologically more dynamic in the earlier phase. The carbon-nitrogen and nitrogen-phosphorus ratios of 11.8 (88.6 : 7.5) and 7.5 (7.5 : 1), respectively, of input fertilizers favoured growth of both heterotrophic and phosphate-solubilizing bacterial populations much better than the other ratios tested. Likewise, water carbon-nitrogen and nitrogen-phosphorus ratios of 11.9 and 3.34 induced bacterial growth. The carbon-nitrogen ratios of 12.63 (101 : 8) (input fertilizer)-4.54 (water), and nitrogen-phosphorus ratios of 8 (8 : 1) (input fertilizer)-2.93 (water), gave gross primary productivity values higher than the remaining ratios, exhibiting overall curvilinear relationships. The values of gross primary productivity were the direct function of values of fertilizer mineralization indices for carbon, nitrogen and phosphorus. CONCLUSION: It is concluded that the mixed fertilizer (carbon-nitrogen-phosphorus-88.6 : 7.5 : 1) comprising cattle dung (95%), poultry droppings (2.5%), urea (2%) and single superphosphate (0.5%), applied at the rate of 23,000 kg ha(-1) year(-1), was a suitable cost-effective fertilization option for aquaculture practices. SIGNIFICANCE AND IMPACT OF THE STUDY: As chemical fertilizers are expensive and cause some adverse effects on the soil structure, composition, microflora and other characteristics of the pond, mixed combinations of inorganic and organics with narrow range of carbon-nitrogen-phosphorus ratio can be suitable and cost-effective fertilization tools in aquaculture practices, which is to be linked with the microbial activities of the pond. 相似文献
75.
Entamoeba histolytica infection still remains one of the major public health problem for developing countries like India. A rapid and accurate detection of this parasite is essential for prevention and control of amoebiasis. In this study, using the method of 'riboprinting' (PCR-RFLP of rRNA genes from amoeba) we have analysed 15 stool samples from symptomatic patients of amoebiasis. All 15 patients of clinical amoebiasis had E. histolytica in their stool and two of the samples also showed mixed infection of E. dispar. Apart from the known restriction enzyme sites within the amoeba SSU-rRNA genes, a new Sau3A site having a discriminatory value is identified in these E. histolytica isolates from India. Hence, it is possible to rapidly identify E. histolytica DNA and differentiating it from E. dispar using minute amounts of clinical stool samples, thus eliminating the laborious parasite culturing process. Thus, riboprinting is advantageous for clearcut identification of E. histolytica in order to decide an effective antiamoebic therapy. 相似文献
76.
Shant J Bhattacharyya S Ghosh S Ganguly NK Majumdar S 《Experimental parasitology》2002,102(3-4):178-186
In this study we have reported the detailed characterization of a 58 kDa excretory-secretory product (ESP) of Giardia lamblia. The method of purification has been simplified which has improved the purification fold as well as the yield of the ESP. The binding efficacy of disialoganglioside (GD2) to the purified ESP was found to be maximum among all other gangliosides used. The N-terminal sequence of the immunoreactive 29 kDa peptide obtained from partial tryptic digest of the ESP was found to be AD-FVPQVST. The IgG against the purified ESP (IgGES) showed cross-reactivity with the binding subunit of the commercially available cholera toxin and also with two protein bands of western cottonmouth moccasin snake toxin. The ESP could accumulate fluid in the intestine of sealed adult mice and also induce morphological changes in HEp-2 cells. The crude extract of G. lamblia trophozoites preincubated with Escherichia coli revealed 8-fold augmentation in the cytopathic activity on HEp-2 cells as compared to that of crude preparation from trophozoites only. 相似文献
77.
The magnocellular visual pathway is believed to receive input from long (L) and middle (M), but not short (S), wavelength-sensitive cones. Recording from neurons in magnocellular layers of lateral geniculate nucleus (LGN) in macaque monkeys, we found that magnocellular neurons were unequivocally responsive to S cone-isolating stimuli. A quantitative analysis suggests that S cones provided about 10% of the input to these cells, on average, while L:M ratios were far more variable. S cone signals influenced responses with the same sign as L and M cone inputs (i.e., no color opponency). Magnocellular afferent recordings following inactivation of primary visual cortex demonstrated that S cone signals were feedforward in nature and did not arise from cortical feedback to LGN 相似文献
78.
Klein DC Ganguly S Coon S Weller JL Obsil T Hickman A Dyda F 《Biochemical Society transactions》2002,30(4):365-373
This paper describes the role 14-3-3 proteins play in vertebrate photoneuroendocrine transduction. 14-3-3 proteins form a complex with arylalkylamine N-acetyltransferase (AANAT), the enzyme which turns melatonin production on during the day and off at night. Complex formation is triggered at night by cAMP-dependent phosphorylation of the enzyme, and results in activation and protection against proteolysis. This enhances melatonin production >10-fold. Light exposure results in dephosphorylation of the enzyme and disassociation from 14-3-3, leading to destruction and a rapid drop in melatonin production and release and circulating levels. 相似文献
79.
Zheng W Zhang Z Ganguly S Weller JL Klein DC Cole PA 《Nature structural biology》2003,10(12):1054-1057
Serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AANAT) controls daily changes in the production and circulating levels of melatonin. Here, the significance of the phosphorylation of AANAT was studied using a semisynthetic enzyme in which a nonhydrolyzable phosphoserine/threonine mimetic, phosphonomethylenealanine (Pma), was incorporated at position 31 (AANAT-Pma31). The results of studies in which AANAT-Pma31 and related analogs were injected into cells provide the first direct evidence that Thr31 phosphorylation controls AANAT stability in the context of the intact cells by binding to 14-3-3 protein. These findings establish Thr31 phosphorylation as an essential element in the intracellular regulation of melatonin production. The application of Pma in protein semisynthesis is likely to be broadly useful in the analysis of protein serine/threonine phosphorylation. 相似文献
80.
Distribution of cells bearing B-cell alloantigen(s) in North Indian rheumatic fever/rheumatic heart disease patients 总被引:1,自引:0,他引:1
Numerous investigators have developed monoclonal antibodies against B-cell alloantigen(s) of rheumatic fever. However, the developed monoclonals do not have the same significance in all the populations. We have developed a battery of monoclonals against B-cell alloantigens of North Indian rheumatic fever patients. In the present study, we have used these monoclonals to examine the frequency of rheumatic antigens in 30 patients with recurrence of rheumatic activity (RRA), 30 of rheumatic heart disease (RHD) patients and 50 controls using alkaline phosphatase anti-alkaline phosphatase (APAAP) technique. These patients were examined at the time of registry and after three months follow up. RRA patients showed higher percentage of lymphocyte positive as compare to RHD and controls. Interestingly, On follow-up RRA patients showed significant decline in positive lymphocyte as compare to first visit whereas no such change was observed in RHD patients. There were 90–93% of RRA and RHD patients positive with these monoclonals. A significant age variation of rheumatic cells was also noticed in all groups of rheumatic patients. We conclude that monoclonals raised from the same ethnic population are highly specific and cost effective to use them to develop an easy field test system such as APAAP, to identify the individual at risk, to develop rheumatic fever. It is also suggested that the alloantigen marker may persist through out life and gets activated after recurrence of the disease. 相似文献