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Microalgae have been proposed as eco-friendly feedstocks for biodiesel production, because they accumulate large amounts of lipids and increase their biomass through photosynthesis. However, the photosynthetic efficiency of microalgae is too low for this strategy to be economically feasible. In an effort to overcome this issue, random mutants with reduced chlorophyll antenna size were generated by ethyl methanesulfonate (EMS)-mediated mutagenesis of Chlorella vulgaris. The antenna size mutant, herein designated E5, exhibited 56.5 and 75.8 % decreases in chlorophyll a and b contents, respectively, with significant reductions in the expression levels of peripheral light-harvesting antenna proteins in photosystem II. The saturated photosynthetic activity and electron transport rate of the E5 mutant were significantly higher and also showed reduced non-photochemical quenching (NPQ), compared to those of the wild type. Consequentially, the E5 mutant cultures achieved 44.5 % improvement in biomass productivity under high light (200 μmol photons m?2 s?1). These results suggest that improving the photosynthetic efficiency of microalgae could greatly enhance their biomass production, and such mutant strains can be applicable for large-scale outdoor cultivation which is typically exposed to high light intensity.  相似文献   
43.
Hao YJ  Wang DH  Peng YB  Bai SL  Xu LY  Li YQ  Xu ZH  Bai SN 《Planta》2003,217(6):888-895
To investigate the regulatory mechanisms of sex expression in cucumber, morphological observations and biochemical analyses were carried out on inappropriate stamen development of female flowers of cucumber. It was found that developmental arrest of the inappropriate stamen mainly occurs at the anther primordium. This arrest is closely correlated with DNA damage, as detected by TUNEL assay, and might result from anther-specific DNase activation. It was also found that the DNA damage does not lead to cell degeneration, although chromatin condensation is observed in the anther primordia.Abbreviations DAPI 4,6-diamidine-2-phenylindole dihydrochloride - MTT 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide - PCD programmed cell death - TUNEL TdT-mediated dUTP nick-end labeling  相似文献   
44.
Biomass-derived volatile fatty acid platform for fuels and chemicals   总被引:1,自引:0,他引:1  
The typical biorefinery platforms are sugar, thermochemical (syngas), carbon-rich chains, and biogas platforms, each offering unique advantages and disadvantages. The sugar platform uses hexose and pentose sugars extracted or converted from plant body mass. The thermochemical (syngas) platform entails a chemical or biological conversion process using pyrolysis or gasification of plants to produce biofuels. The carbon-rich chains platform is used to produce biodiesel from long-chain fatty acids or glycerides. In the present work, we suggest a new platform using volatile fatty acids (VFAs) for the production of biofuels and biochemicals production. The VFAs are short-chain fatty acids composed mainly of acetate and butyrate in the anaerobic digestion (AD) process, which does not need sterilization, additional hydrolysis enzymes (cellulose or xylanase), or a high cost pretreatment step. VFAs are easily produced from almost all kinds of biomass with low lignin content (terrestrial, aquatic, and marine biomass) by the AD process. Considering that raw material alone constitutes 40∼80% of biofuel production costs, biofuels made from VFAs derived from waste organic biomass potentially offer significant economical advantage.  相似文献   
45.
46.
High-level production of human leptin by fed-batch culture of recombinant Escherichia coli using constitutive promoter system was investigated. For the constitutive expression of the obese gene encoding human leptin, the strong constitutive HCE promoter cloned from the D-amino acid aminotransferase gene of Geobacillus toebii was used. To develop an optimal host-vector system, several different recombinant E. coli strains were compared for leptin production. In flask cultures, E. coli FMJ123, which is a rpoS mutant strain, showed the highest level of leptin production (41% of total proteins). By comparing the expression levels of leptin in several different rpoS- and rpoS+ strains, it could be concluded that rpoS mutation positively affected constitutive production of leptin. For the large-scale production of human leptin, fed-batch cultures of recombinant E. coli FMJ123 were carried out using three different feeding solutions--chemically defined, yeast extract-containing, and casamino acid-containing feeding solutions. Among these, the use of casamino acid-containing feeding solution allowed production of leptin up to 2.1 g/L, which was 2.1- and 1.8-fold higher than that obtained with chemically defined and yeast extract-contained feeding solutions, respectively. These results suggest that the HCE promoter can be used for the efficient production of leptin, and most likely other recombinant proteins, in a constitutive manner.  相似文献   
47.
Chronic inflammation is closely associated with metabolic disorders such as obesity and type 2 diabetes, however, the underlying mechanism is unclear. Toll-like receptors (TLRs) play a key role in innate immune response as well as inflammatory signals. Here, we observed that mRNA level of TLR4 was induced during adipocyte differentiation and remarkably enhanced in fat tissues of obese db/db mice. In addition, activation of TLR4 with either LPS or free fatty acids stimulated NFkappaB signaling and expression of inflammatory cytokine genes, such as TNFalpha and IL-6 in 3T3-L1 adipocytes. Furthermore, we discovered that TLR4 activation in 3T3-L1 adipocytes provoked insulin resistance. Taken together, these results suggest that activation of TLR4 in adipocyte might be implicated in the onset of insulin resistance in obesity and type 2 diabetes.  相似文献   
48.
A bacterial strain named AB-4 showing algicidal activity against Chattonella marina was isolated from coastal water of ULjin, Republic of Korea. The isolated strain was identified as Bacillus sp. by culture morphology, biochemical reactions, and homology research based on 16S rDNA. The bacterial culture led to the lysis of algal cells, suggesting that the isolated strain produced a latent algal-lytic compound. Amongst changes in algicidal activity by different culture filtrate volumes, the 10% (100 μl/ml) concentration showed the biggest change in algicidal activity; there, estimated algicidal activity was 95%. The swimming movements of Chattonella marina cells were inhibited because of treatment of the bacterial culture; subsequently, Chattonella marina cells became swollen and rounded. With longer exposure time, algal cells were disrupted and cellular components lost their integrity and decomposed. The released algicide(s) were heat-tolerant and stable in pH variations, except pH 3, 4, and 5. Culture filtrate of Bacillus sp. AB-4 was toxic against harmful algae bloom (HAB) species and nontoxic against livefood organisms. Bacillus sp. AB-4 showed comparatively strong activity against Akashiwo sanguinea, Fibriocapsa japonica, Heterosigma akashiwo, and Scrippsiella trochoidea. These results suggest that the algicidal activity of Bacillus sp. AB-4 is potentially useful for controlling outbreaks of Chattonella marina.  相似文献   
49.
抗人B7-H1单克隆抗体的制备和鉴定   总被引:1,自引:0,他引:1  
目的:采用杂交瘤技术制备抗人B7-H1单克隆抗体,并对其进行鉴定。方法:经抗原免疫的小鼠脾细胞与小鼠骨髓瘤细胞以常规方法融合;用间接ELISA法筛选分泌抗体的杂交瘤细胞株;阳性克隆用有限稀释法获得稳定分泌抗人B7-H1单克隆抗体的杂交瘤细胞株;扩增杂交瘤细胞注射进小鼠腹腔后制备腹水;纯化腹水中的单克隆抗体并对其亚型进行鉴定;用间接ELISA法测抗体效价;将肺癌组织制成石蜡切片,用抗人B7-H1抗体进行免疫组化染色。结果:获得1株稳定分泌抗人B7-H1单克隆抗体的杂交瘤细胞株,所分泌的单抗类型为IgG1;抗体效价为1×108,纯化后的抗体含量为6.76g/L;免疫组化实验中,单抗可与肺癌组织表面的B7-H1蛋白特异地结合。结论:制备了人B7-H1单克隆抗体,为B7-H1检测试剂盒的研制奠定了基础。  相似文献   
50.
Epstein-Barr virus (EBV) is a B-lymphotropic human herpes virus that infects B lymphocytes and is associated with a broad spectrum of benign and malignant diseases. B cell infection by EBV causes indefinite cell proliferation that results in the development of immortalized lymphoblastoid cell lines (LCLs). We found that SNU-1103, a latency type III EBV-transformed LCL developed from a Korean cancer patient, resisted the G1 arrest that was normally caused by serum starvation. Western blot analyses revealed several alterations in the expression of key regulatory cell cycle proteins involved in the G1 phase. High expression of cyclin D2 and time-dependent increases in cyclin-dependent kinase 6 (CDK6) and cyclin D3 were observed in SNU-1103 during serum starvation. Very unexpectedly, in SNU-1103, the key G1 phase CDK inhibitor p21CiP1 was expressed at a consistently high level, while p27KiP1 expression was increased. Of three pRb family proteins, pRb expression was reduced and it became hypophosphorylated in SNU-1103 during serum starvation. Instead, p107 and p130 were expressed at consistently high levels in SNU-1103 during serum starvation. In conclusion, compared with an EBV-negative BJAB cell line, multiple cell cycle regulatory proteins were abnormally or inversely expressed in SNU-1103 during serum starvation.  相似文献   
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