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1.
Justin C. Luong Patrick L. Turner Celina N. Phillipson Katja C. Seltmann 《Ecological Entomology》2019,44(4):471-479
1. It is hypothesised that ecological restoration in grasslands can induce an alternative stable state shift in vegetation. The change in vegetation influences insect community assemblages and allows for greater functional redundancy in pollination and refuge for native insect species. 2. Insect community assemblages at eight coastal California grassland sites were evaluated. Half of these sites had undergone restoration through active revegetation of native grassland flora and half were non‐restored. Insects were collected from Lupinus bicolor (Fabaceae) within 2 × 2‐m2 plots in spring 2017. Lupinus bicolor is a common native species that is used in California restoration projects, and home and state landscaping projects. 3. Ordination demonstrated that insect community assemblages were different between restored and non‐restored sites. These differences were seen in insect functional groups as well as taxa‐specific differences and were found to be driven by environmental characteristics such as non‐native forb cover. 4. Functional redundancy of herbivores decreased at restored sites, while pollinators became more redundant compared with non‐restored sites. The assemblages of the common species found at restoration sites contained more native insects than those found at non‐restored sites, including species such as Bombus vosnesenskii. 5. Local grassland restoration has the potential to induce an alternative stable state change and affect insect community assemblages. Additionally, it was found that grassland restoration can be a potential conservation tool to provide refugia for bumblebees (Bombus), but additional studies are required to fully understand its broader applicability. 相似文献
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Summary Phage adsorption tests and transfection by electroporation were carried out to decide whether phage-resistance in Lactococcus lactis subsp. lactis strain 4513-5 is based on intracellular or extracellular mechanisms. Using high voltage (12.5 kV/cm) electroporation, untreated phage DNA was introduced into phage-sensitive and phage-resistant cells. Since phages showed low adsorption frequencies on resistant bacteria, resistance is localized in the cell wall preventing phage DNA from entering the cell. This is the only mechanism responsible for the resistance of L. lactis subsp. lactis 4513-5 against its homologous phage P4513-K12 and non-homologous phages P05M-13 and P05M-47, but not against phage P530-7 and phage P530-12. In the case of the latter two phage strains, intracellular resistance mechanisms are involved and discussed. 相似文献
5.
Phytic acid. A natural antioxidant 总被引:14,自引:0,他引:14
The catalysis by iron of radical formation and subsequent oxidative damage has been well documented. Although many iron-chelating agents potentiate reactive oxygen formation and lipid peroxidation, phytic acid (abundant in edible legumes, cereals, and seeds) forms an iron chelate which greatly accelerates Fe2+-mediated oxygen reduction yet blocks iron-driven hydroxyl radical generation and suppresses lipid peroxidation. Furthermore, high concentrations of phytic acid prevent browning and putrefaction of various fruits and vegetables by inhibiting polyphenol oxidase. These observations indicate an important antioxidant function for phytate in seeds during dormancy and suggest that phytate may be a substitute for presently employed preservatives, many of which pose potential health hazards. 相似文献
6.
Enzymatic and morphological response of the thymus to drugs in normal and zinc-deficient pregnant rats and their fetuses 总被引:1,自引:0,他引:1
In the thymus of normally fed pregnant rats the plasma membrane enzymes dipeptidyl peptidase IV (DPP IV) and alkaline phosphatase (alP) were found in cortical and medullary lymphocytes (thymocytes). Plasma membrane aminopeptidase A (APA) and adenosine monophosphate hydrolysing phosphatase (AMPP) were present in cortical reticular cells. In medullary reticular cells, aminopeptidase M (APM), gamma-glutamyl transferase (GGT), adenosine triphosphate (ATPP) and thiamine pyrophosphate (TPPP) cleaving phosphatases were detected. Medullary reticular cells did not contain APA. Lysosomal DPP I and II, acid phosphatase, acid beta-D-galactosidase, beta-D-N-acetyl-glucosaminidase, beta-D-glucuronidase and non-specific esterases occurred especially in macrophages at the corticomedullary junction. The 21-day-old fetal thymus showed a similar reaction pattern as the maternal organ except for APA which was absent before birth. After treatment of the pregnant rats with valproic acid (VPA), salicylic acid (SA), streptozotocin (ST) and retinoic acid (RA) APA showed an increase in activity in the thymic cortex. In addition, ST and RA induced AMPP, ATPP and TPPP activity in cortical reticular cells up to the same pattern as in medullary reticular cells. After ethanol (ET) administration severe damages occurred. The thymic cortex was free of DPP IV-positive lymphocytes; the medullary reticular cells showed reduced or no GGT and occasionally an increased APM activity. Dexamethasone (DEXA) given to normal or zinc-deficient rats produced the most severe lesions; thymocytes with DPP IV activity were completely absent in the cortex and medulla. In Zn-deficient pregnant rats similar alterations were observed as after ET.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
M E Kugler-Steigmeier U Friederich U Graf W K Lutz P Maier C Schlatter 《Mutation research》1989,211(2):279-289
Various substituted aniline derivatives were tested for genotoxicity in several short-term tests in order to examine the hypothesis that a substitution at both ortho positions (2,6-disubstitution) could prevent genotoxicity due to steric hindrance of an enzymatic activation to electrophilic intermediates. In the Salmonella/microsome assay, 2,6-dialkylsubstituted anilines and 2,4,6-trimethylaniline (2,4,6-TMA) were weakly mutagenic in strain TA100 when 20% S9 mix was used, although effects were small compared to those of 2,4-dimethylaniline and 2,4,5-trimethylaniline (2,4,5-TMA). In Drosophila melanogaster, however, 2,4,6-TMA and 2,4,6-trichloroaniline (TCA) were mutagenic in the wing spot test at 2-3 times lower doses than 2,4,5-TMA. In the 6-thioguanine resistance test in cultured fibroblasts, 2,4,6-TMA was again mutagenic at lower doses than 2,4,5-TMA. Two methylene-bis-aniline derivatives were also tested with the above methods: 4,4'-methylene-bis-(2-chloroaniline) (MOCA) was moderately genotoxic in all 3 test systems whereas 4,4'-methylene-bis-(2-ethyl-6-methylaniline) (MMEA) showed no genotoxicity at all. DNA binding studies in rats, however, revealed that both MOCA and MMEA produced DNA adducts in the liver at levels typically found for moderately strong genotoxic carcinogens. These results indicate that the predictive value of the in vitro test systems and particularly the Salmonella/microsome assay is inadequate to detect genotoxicity in aromatic amines. Genotoxicity seems to be a general property of aniline derivatives and does not seem to be greatly influenced by substitution at both ortho positions. 相似文献
8.
Hepatocytes in the proximal (zone 1) and distal (zone 3) regions of the liver acinus are selectively stained by perfusion of the isolated rat liver with 0.2-20 microM acridine orange (AO). After 10-60 min of anterograde perfusion, AO fluorescence is visible in zone 1 cells, whereas retrograde perfusion stains cells of zone 3. In this paper, we describe a technique to isolate a mixed population of fluorescent and nonfluorescent hepatocytes (cells from all acinar zones, which do not loose the zone specific AO labeling) and to separate these cells according to their zonal origin by fluorescence activated cell sorting. The zonal populations obtained were either fluorescent or nonfluorescent (purity greater than 95%). Separated cell fractions differed in their enzyme content (5' nucleotidase, succinate-dehydrogenase, beta-glucuronidase). An unidentified AO metabolite, which is not found in bile after retrograde perfusion (not formed in zone 3 cells), is also absent after retrograde perfusion in sorted fluorescent cells (zone 3 cells), indicating zonal purity of sorted cells. 相似文献
9.
Non-pregnant rats fed an Mg-deficient diet showed some degenerated and calcified proximal tubules in the inner region of the medullary rays accompanied by reduced or absent enzyme activities. After gentamicin treatment some damaged convoluted proximal tubules occurred. Enzyme histochemistry revealed decreased activities for brush border and lysosomal hydrolases; using immunohistochemistry lesions were detectable for the cytoskeletal proteins keratin and vimentin. Administration of gentamicin to Mg-deficient rats led to a further decrease of hydrolase activities in obviously intact proximal tubules and drastic structural and enzymatic defects as well as alterations of the cytoskeletal proteins in the convoluted and straight segments of other proximal tubules and to a lesser degree also in glomeruli and further portions of the tubular apparatus including the collecting ducts. 相似文献
10.
J. D. Graf 《Genetics》1989,123(2):389-398
Inheritance of alleles at 29 electrophoretically detected protein loci and one pigment locus (albinism) was analyzed in Xenopus laevis by backcrossing multiply heterozygous individuals generated by intersubspecies hybridization. Pairwise linkage tests revealed eight classical linkage groups. These groups have been provisionally numbered from 1 to 8 in an arbitrarily chosen order. Linkage group 1 includes ALB-2 (albumin), ADH-1 (alcohol dehydrogenase), NP (nucleoside phosphorylase), and ap (periodic albinism). Linkage group 2 contains ALB-1 and ADH-2, and probably is homeologous to group 1. Linkage group 3 comprises PEP-B (peptidase B), MPI-1 (mannosephosphate isomerase), SORD (sorbitol dehydrogenase), and mIDH-2 (mitochondrial isocitrate dehydrogenase). Linkage group 4 contains GPI-1 (glucosephosphate isomerase) and EST-4 (esterase 4). Linkage group 5 contains GPI-2 and PEP-D (peptidase D). Linkage group 6 comprises ACP-3 (acid phosphatase), sME (cytosolic malic enzyme), and GLO-2 (glyoxalase). Linkage group 7 consists of sSOD-1 (cytosolic superoxide dismutase), GPD-2 (glycerol-3-phosphate dehydrogenase), mME (mitochondrial malic enzyme), and the sex determining locus. Linkage group 8 includes FH (fumarate hydratase) and TRF (transferrin). Recombination frequencies between linked loci showed differences related to the genomic constitution (parental subspecies) and to the sex of the heterozygous parent. Independent assortment was observed between the duplicate ALB loci. This is true for the duplicate ADH, GLO, and MPI loci as well, supporting the view that these genes have been duplicated as part of a genome duplication that occurred in the evolutionary history of X. laevis. Comparative analysis of genetic maps reveals a possible conservation of several linkages from the Xenopus genome to the human genome. 相似文献