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71.
Oyofo BA Subekti D Tjaniadi P Machpud N Komalarini S Setiawan B Simanjuntak C Punjabi N Corwin AL Wasfy M Campbell JR Lesmana M 《FEMS immunology and medical microbiology》2002,34(2):139-146
The prevalence of bacteria, parasite and viral pathogens in 3875 patients with diarrhea in community and hospital settings from March 1997 through August 1999 in Jakarta, Indonesia was determined using routine bacteriology and molecular assay techniques. Bacterial pathogens isolated from hospital patients were, in decreasing frequency, Vibrio cholerae O1, Shigella flexneri, Salmonella spp. and Campylobacter jejuni, while S. flexneri, V. cholerae O1, Salmonella spp. and C. jejuni were isolated from the community patients. V. cholerae O1 was isolated more frequently (P<0.005) from the hospital patients than the community patients. Overall, bacterial pathogens were isolated from 538 of 3875 (14%) enrolled cases of diarrhea. Enterotoxigenic Escherichia coli were detected in 218 (18%) of 1244 rectal swabs. A small percentage of enterohemorrhagic E. coli (1%) and of Clostridium difficile (1.3%) was detected. Parasitic examination of 389 samples resulted in 43 (11%) positives comprising Ascaris lumbricoides (1.5%), Blastocystis hominis (5.7%), Giardia lamblia (0.8%), Trichuris trichiura (2.1%) and Endolimax nana (0.5%). Rotavirus (37.5%), adenovirus (3.3%) and Norwalk-like virus (17.6%) were also detected. Antimicrobial resistance was observed among some isolates. Bacterial isolates were susceptible to quinolones, with the exception of some isolates of C. jejuni which were resistant to ciprofloxacin, nalidixic acid and norfloxacin. Data obtained from this community- and hospital-based study will enable the Indonesian Ministry of Health to plan relevant studies on diarrheal diseases in the archipelago. 相似文献
72.
Fusarium oxysporum f.sp. cubense is the causal pathogen of wilt disease of banana. A cost-effective measure of control for this disease is still not available.
Streptomyces violaceusniger strain G10 acts as an antifungal agent antagonistic towards many different phytopathogenic fungi, including different pathogenic
races of the Fusarium wilt pathogen. In an attempt to understand the mode of action of this antagonist in nature, the interaction between S. violaceusniger strain G10 and F. oxysporum f.sp. cubense was first studied by paired incubation on agar plates. Evidence for the in vitro antibiosis of strain G10 was demonstrated by inhibition zones in the “cross-plug” assay plates. Microscopic observations
showed lysis of hyphal ends in the inhibited fungal colonies. Culture of strain G10 in liquid media produces antifungal metabolites,
which showed in vitro antagonistic effects against F. oxysporum f.sp. cubense such as swelling, distortion and excessive branching of hyphae, and inhibition of spore germination. An indirect method was
used to show that antibiosis is one of the mechanisms of antagonism by which strain G10 acts against F. oxysporun f.sp. cubense in soil. This study suggests the potential of developing strain G10 for the biological control of Fusarium wilt disease of banana. Journal of Industrial Microbiology & Biotechnology (2002) 28, 303–310 DOI: 10.1038/sj/jim/7000247
Received 08 August 2001/ Accepted in revised form 16 February 2002 相似文献
73.
Marrs BL 《Photosynthesis research》2002,73(1-3):55-58
The development of genetics as a tool for the study of photosynthesis is recounted, beginning in the period when no genetic
exchange mechanism was known for any photosynthetic microorganism, and ending with the sequencing of the key genes for photosynthesis.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
74.
75.
Christopher?T.?WalshEmail author Sarah?E.?O'Connor Tanya?L.?Schneider 《Journal of industrial microbiology & biotechnology》2003,30(8):448-455
The epothilones are a family of macrolactone natural products from the myxobacterial species Sorangium cellulosum. Similar to taxol, they are of current clinical interest as anticancer agents. Sequence analysis of the epothilone gene cluster
allowed the identification of polyketide synthase and nonribosomal peptide synthetase modules involved in catalyzing epothilone
biosynthesis. Given this information, it has been possible to test the predicted functions of several modules to date. EpoA
ACP, EpoB, and EpoC have been overproduced in Escherichia coli, allowing in vitro reconstitution of the EpoA/B/C interface and production of the expected epothilone precursor. Further
experiments probed the tolerance of EpoB and EpoC for unnatural substrates. These studies of the first three modules of the
epothilone biosynthetic cluster suggest that combinatorial biosynthesis may lead to the production of a variety of epothilone
analogs that incorporate diversity into the heterocycle starter unit. Additional efforts with the remaining modules, coupled
with increased understanding of the macrocyclizing thioesterase domain, may lead to the production of epothilone variants
with improved clinical properties. 相似文献
76.
Tarka-Leeds DK Herr DW Klinefelter GR Rogers JM 《Birth defects research. Part B, Developmental and reproductive toxicology》2003,68(4):383-390
BACKGROUND: Microtia is a reduction in pinna size, usually seen in humans in conjunction with other medical conditions. We report microtia in CD‐1 mice after gestational exposure to ethane dimethanesulfonate (EDS), an alkylating agent and adult rat Leydig cell toxicant. METHODS: Time‐pregnant CD‐1 mice were administered 0, 80, or 160 mg EDS/kg on gestation days (GD) 11–17, or 0 or 160 mg EDS/kg on GD 11–13, GD 13–15 or GD 15–17. Pinnae were measured on postnatal days (PND) 4, 8, 18, and 28; and were observed for detachment from birth through PND 8. Branchial‐arch derived skeletal structures and histology of the pinna was examined on PND 4 and 24. Brainstem auditory evoked response (BAER) tests were carried out at approximately PND 160 to determine possible effects on hearing. RESULTS: All offspring of EDS‐treated dams exhibited bilateral, dose‐related decreases in pinna size. Gestational exposure during GD 11–13 produced smaller ears than during GD 13–15 or 15–17, but not as small as the GD 11–17 regimen. Ossification of other pharyngeal arch derivatives was delayed whereas histology was unremarkable. BAER analysis showed a decrease in the proportion of adult offspring producing a quantifiable response to varied auditory stimuli among EDS‐treated litters. CONCLUSIONS: Gestational exposure to EDS affects pinna development in the mouse, with a broad period of sensitivity during the second half of gestation. Microtia induced by EDS may be associated with hearing deficits, suggesting functional importance of pinna size or additional effects of EDS on ear development not detected by morphological examination. Birth Defects Res B68:383–390, 2003. © 2003 Wiley‐Liss, Inc. 相似文献
77.
EDDHA added in an optimal concentration (20.5 mumol.L-1) to a modified Pirson-Seidel nutrient solution induces flowering in some clones of the species Lemna minor, Lemna gibba and Spirodela polyrrhiza, which in the absence of EDDHA in the same nutrient solution do not flower. By adding EDDHA (20.5 mumol.L-1), floral induction under LD conditions is optimally promoted in the long-day (LD) species Lemna minor. After adding EDDHA to the nutrient solution, before floral induction and during flowering, Zn, Mn and Cu content is significantly increased in plants. Zn-EDDHA (0.86 mumol.L-1), Mn-EDDHA (1.51 mumol.L-1) and Cu-EDDHA (0.12 mumol.L-1), when used individually, greatly promote flowering under LD conditions as compared to flowering in the same nutrient solution with an equivalent quantity of Zn, Mn or Cu in the nonchelate form. If, on the other hand, Zn-EDDHA and Mn-EDDHA are added to the nutrient solution together (instead of Zn and Mn in nonchelate form), their effect on the promotion of flowering is less than in the case of their individual use. This shows that there is antagonism between Zn-EDDHA and Mn-EDDHA that is eliminated by adding EDDHA to the nutrient solution. We obtained the highest percentage of flowering plants (i.e. 74%) if we added EDDHA (20.5 mumol.L-1) to the nutrient solution containing Mn, Zn and Cu in chelate form. 74% of flowering plants actually means that flowering was achieved in all physiologically mature plants. Our results show that EDDHA promotes floral induction in Lemna minor under LD conditions, especially through chelating Zn, Mn and Cu, and, in addition, through eliminating the antagonism between Mn and Zn chelates EDDHA. Zn-EDDHA (0.86 mumol.L-1) also promote floral differentiation, especially cell division of microspore mother cells into dyads and those into microspore tetrads, which can be seen in microphotographs. When investigating possible pathways through which Mn-EDDHA, Zn-EDDHA and Cu-EDDHA promote flowering, we studied the effects of various concentrations of IAA and sucrose added to the nutrient solution as well. The results support the hypothesis that one of the possible pathways in which Mn-EDDHA promotes floral induction is through auxin oxidase, whereas Zn-EDDHA and Cu-EDDHA probably promote it through the enhancement of the photosynthesis and synthesis of sucrose. 相似文献
78.
A convenient method for determining the absolute configuration of chiral secondary alcohols using the racemic NMR anisotropy reagent, (+/-)-2-methoxy-2-(1-naphthyl)propionic acid [(+/-)-M(alpha)NP acid], and an HPLC-CD detector was developed. The method was successfully applied to some chiral alcohols derived from (-)-alpha-santonin. 相似文献
79.
The rate of expansion of bacterial colonies of S. liquefaciens is investigated in terms of a mathematical model that combines biological as well as hydrodynamic processes. The relative
importance of cell differentiation and production of an extracellular wetting agent to bacterial swarming is explored using
a continuum representation. The model incorporates aspects of thin film flow with variable suspension viscosity, wetting,
and cell differentiation. Experimental evidence suggests that the bacterial colony is highly sensitive to its environment
and that a variety of mechanisms are exploited in order to proliferate on a variety of surfaces. It is found that a combination
of effects are required to reproduce the variation of bacterial colony motility over a large range of nutrient availability
and medium hardness.
Received: 29 April 1999 相似文献
80.
Susanna Sánchez deViala Bill B. Brodie Eloy Rodriguez Donna M. Gibson 《Journal of nematology》1998,30(2):192-200
Thiarubrine C, a polyacetylenic 1,2-dithiin isolated from the roots of Rudbeckia hirta (Asteraceae), exhibited strong nematicidal activity in in vitro and growth chamber assays. Thiarubrine C was toxic, in the absence of light, to the plant-parasitic nematodes Meloidogyne incognita and Pratylenchus penetrans at LC₅₀s of 12.4 ppm and 23.5 ppm, respectively. A minimum exposure time between 12 and 24 hours was the critical period for nematode mortality due to thiarubrine C. Although thiarubrine C was not totally dependent on light for toxicity, activity was enhanced in the presence of light, especially with the microbivorous nematode, Teratorhabditis dentifera. Upon exposure of M. incognita juveniles to 20 ppm thiarubrine C for 1 hour, infection of tomato plants was greatly reduced compared to untreated checks. Thiarubrine C was also effective in reducing plant infection when mixed with soil 24 hours prior to or at planting, unlike other related compounds such as δ-terthienyl. 相似文献