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991.
992.
Microenvironments and microbial community structure in sediments 总被引:3,自引:0,他引:3
The aim of this study was to explore the potential of a combined chemical and microbiological approach as part of a study of organic carbon oxidation processes in sediments. An assessment of microbiological diversity using molecular techniques was carried out in combination with high resolution chemical measurements at the sediment-water interface of a coastal lagoon affected by eutrophication in autumn 2000. There was a 0.2 mm overlap between the O2 and H2S profiles. pH showed a maximum just above the sediment-water interface coinciding with an oxygen maximum, suggesting photosynthetic activity, and a minimum coinciding with the O2-H2S interface. The redox potential was high in bottom water and surface sediment, reflecting the presence of oxygen and oxides, and reached low values after a step-wise decrease at -18 mm. Reduction of Fe occurred within the biofilm at the O2-H2S interface and was mostly due to reduction by H2S. The elevated concentrations of dissolved Mn in the oxic water may have been caused either by in situ production within organic aggregates or lateral water flow from sites nearby at which Mn2+ diffuses out of the sediment. Sequences related to sulphur chemolitotrophs were retrieved from the biofilm samples, which is consistent with the small overlap between O2 and H2S observed in this biofilm. Although the resolution of techniques used was different, sequencing results were consistent with chemical data in delineating the same horizons according to redox, pH or ecological properties. 相似文献
993.
Lóránd T Molnár P Deli J Tóth G 《Journal of biochemical and biophysical methods》2002,53(1-3):251-258
FT-IR spectroscopy was applied to investigate 15 different carotenoids. The following compounds were examined: beta-carotenone (1); semi-beta-carotenon-epoxide (2); beta-apo-8'-carotenal (3); ethyl-beta-apo-8'-carotenoate (4); beta-citraurin (5); 5,6-Epoxy-beta-caroten-8'-al (6); beta-citraurin-epoxide (7); apo-10'-violaxanthal (8); persicaxanthin (9); capsylaldehyde (10); capsanthylal (11); retinol (12); retinal (13); retinoic acid (14); and bixin (15). Some characteristic functional groups (Cz.dbnd;C, Cz.dbnd;O, CHO, OH, etc.) were identified. We focused on the influence of conjugation of the keto-, aldehyde- and ester groups on the absorption of the Cz.dbnd;C bonds. This method is useful in the fast analysis of the biologically important carotenoids especially if there are small samples available. 相似文献
994.
Ivanova M Tzvetanova E Jetcheva V Kilár F 《Journal of biochemical and biophysical methods》2002,53(1-3):141-150
Capillary zone electrophoresis and high-resolution agarose gel electrophoresis were compared to detect protein components in serum and cerebrospinal fluid of patients. Both electrophoretic methods proved to be useful for detection of protein abnormalities (e.g., mono- and oligoclonal bands) in biological fluids, but capillary electrophoresis offered several important advantages, such as sample application without preliminary concentration, lack of staining procedures, and on-line evaluation of patterns. Furthermore, capillary electrophoresis exhibits shorter analysis time and high resolution with low baseline noise. The results were proven to be powerful in diagnosis and monitoring of dyscrasias in routine laboratory practice. 相似文献
995.
Rezeli M Világhy B Kilár F Kanyó K Török B Török A 《Journal of biochemical and biophysical methods》2002,53(1-3):151-156
Human ovarian follicular fluids and sera obtained from women pre-treated for in vitro fertilization (IVF) were investigated by capillary zone electrophoresis. Comparison of the matching physiological liquids showed substantial differences in the electrophoretic patterns. Significant decrease in the alpha(1)- and gamma-fractions of follicular fluids of every woman were observed, whereas other fractions of the samples did not show such alterations. Since follicular fluid is a product of both, secretion by granulosa cells and diffusion from the theca capillaries, we can assume that the forced production of follicular fluid upon hormone stimulation (with gonadotropin releasing hormone (GnRH), follicle stimulating hormone (FSH) and corionic gonadotroph hormone (hCG)) may play role in the uneven presence of the proteins. 相似文献
996.
Kunsági-Máté S Bitter I Grün A Nagy G Kollár L 《Journal of biochemical and biophysical methods》2002,53(1-3):101-108
The 'host' properties of distally dialkylated calix[4]arenes and 4-tert-butylcalix[4]arenes in the presence of 1-chloro-4-(trifluoromethyl)benzene (BFT) were studied in chloroform solvent by intensity-independent spectrofluorometric method. The anisotropy decay experiments were found as suitable method to indicate the host-guest complex formation but it is unable to determine the strength of supramolecular interaction. 相似文献
997.
Three types of chiral stationary phase were used to achieve chromatographic resolution of enantiomers of rac-11-dihydrooracin (DHO), the principal metabolite of a potential cytostatic drug oracin. Chiralcel OD-R as a chiral stationary phase with mobile phase comprising acetonitrile (modifier) and sodium perchlorate (buffering component) proved to be the most suitable system. Chemometric optimisation based on the Box-Wilson central composite design was employed to find the optimum resolution. The optimum factor space was defined by three parameters: temperature, modifier concentration and buffer concentration. Newly designed chromatographic response functions based on a combination of resolution R(S) and retention time of the last component eluted t(RL) were employed to evaluate the resolution with regard to quality and quantity. Optimum values predicted from those models of response surfaces were in excellent agreement with the experimental results. The chromatographic resolution of DHO enantiomers is suitable for xenobiochemical studies on stereoselectivity and stereospecificity of biotransformation enzymes. 相似文献
998.
Evrard JL Nguyen I Bergdoll M Mutterer J Steinmetz A Lambert AM 《Plant molecular biology》2002,49(6):611-620
We describe here a new -tubulin isoform from sunflower we named -tubulin. -tubulin is the most divergent higher-plant -tubulin described so far, having an unusual deletion in the H1/B2 loop and a glutamine-rich C-terminus. We constructed a three-dimensional model and discuss its implications. Using specific antibodies, we show that -tubulin expression is restricted to the male gametophyte. -tubulin mRNA represents 90% of -tubulin mRNA and a small percentage of total pollen mRNA. Among the plants tested, -tubulin was only detected in sunflower and in Cosmos. Since both plants are Asteraceae, we propose that -tubulin is specific to this family. Our results suggest that -tubulin can inhibit tubulin assembly in pollen. This hypothesis is reinforced by the fact that -tubulin is found in a complex with -tubulin in mature sunflower pollen. 相似文献
999.
A trial is described, in the state of Rio Grande do Sul, southern Brazil, as one of a series suggested to investigate the
effects of strategic but selective acaricide treatments of cattle within herds against Boophilus microplus. They are aimed at considering the repercussions of farmer attempts at immediate reductions in acaricide costs and the potential
for creation of ‘refugia’ of untreated ticks. Half (Group 1) of a small experimental herd of European breed heifers were treated
strategically against ticks, three times during the late spring–early summer and twice during autumn (southern hemisphere),
with an injectable avermectin endectocide, designed to act directly against the first and third generations of parasitic B. microplus per ‘cattle tick year’ at this site, respectively. The consequent levels of infestations on all of the member cattle in their
common pasture were monitored. Group 1 showed low to zero tick counts during the 28-day treatment interval periods and up
to ca. 14 days after the last of such a series. Treated cattle, however, became re-infested outside of these periods and to
levels that would be considered as unacceptable by farmers in the state. The untreated cattle (Group 2) showed infestations
at generally higher levels, than their contemporaries, within and outside of the treatment periods. There were thus ample
sources of larvae in the pasture, derived principally from falling, untreated engorged female ticks, re-infesting both the
treated and untreated cattle. Advantages of maintaining chemically untreated cattle ticks within a herd, compared to their
disadvantages as contaminants to classical strategic control procedures, merit re-evaluation, especially in relation to the
recent, world-wide resurgence of acaricide resistance in B. microplus.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
1000.