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991.
992.
Emily Kathryn Brown 《Behavioural processes》2009,81(2):250-255
The current experiment investigates whether an active time model can account for anomalous results that have emerged from multiple schedule, concurrent variable-interval (VI) VI experiments. The model assumes that (1) during concurrent VI VI training pigeons learn a function that relates time since the most immediate response, i.e., active time, to changeover probabilities and (2) that molar preference is the result of an interaction between inter-response time frequencies and the learned active time changeover functions. Pigeons were trained under a concurrent VI 30-s VI 30-s schedule and a concurrent VI 60-s VI 60-s schedule. Probes were conducted in which VI 30-s and VI 60-s stimuli were paired. During these probes, birds allocated choices equally to the stimuli. The active time model accurately fit individual subject data. In contrast data were not fit by a variant of scalar expectancy theory proposed by Gibbon [Gibbon, J., 1995. Dynamics of time matching: arousal makes better seem worse. Psychon. Bull. Rev. 2, 208-215]. 相似文献
993.
Effect of salt on aerobic biodegradation of petroleum hydrocarbons in contaminated groundwater 总被引:2,自引:0,他引:2
Ulrich AC Guigard SE Foght JM Semple KM Pooley K Armstrong JE Biggar KW 《Biodegradation》2009,20(1):27-38
Hydrocarbon-contaminated soil and groundwater at oil and gas production sites may be additionally impacted by salts due to
release of produced waters. However, little is known about the effect of salt on the in-situ biodegradation of hydrocarbons
by terrestrial microbes, especially at low temperatures. To study this effect, we prepared a groundwater-soil slurry from
two sites in Canada: a former flare pit site contaminated with flare pit residue (Site A), and a natural gas processing facility
contaminated with natural gas condensate (Site B). The slurry with its indigenous microbes was amended with radiolabeled hydrocarbons
dissolved in free product plus nutrients and/or NaCl, and incubated in aerobic biometer flasks with gyrotory shaking at either
25 or 10°C for up to 5 weeks. Cumulative production of 14CO2 was measured and the lag time, rate and extent of mineralization were calculated. For Site A, concentrations of NaCl ≥1%
(w/v) delayed the onset of mineralization of both 14C-hexadecane and 14C-phenanthrene under nutrient-amended conditions, but once biodegradation began the degradation rates were similar over the
range of salt concentrations tested (0–5% NaCl). For Site B, increasing concentrations of NaCl ≥1% (w/v) increased the lag
time and decreased the rate and extent of mineralization of aliphatic and aromatic substrates. Of particular interest is the
observation that low concentrations of salt (≤1% NaCl) slightly stimulated mineralization in some cases. 相似文献
994.
995.
Enpeng Zhao Mark P. Keller Mary E. Rabaglia Angie T. Oler Donnie S. Stapleton Kathryn L. Schueler Elias Chaibub Neto Jee Young Moon Ping Wang I-Ming Wang Pek Yee Lum Irena Ivanovska Michele Cleary Danielle Greenawalt John Tsang Youn Jeong Choi Robert Kleinhanz Jin Shang Yun-Ping Zhou Andrew D. Howard Bei B. Zhang Christina Kendziorski Nancy A. Thornberry Brian S. Yandell Eric E. Schadt Alan D. Attie 《Mammalian genome》2009,20(8):476-485
Type 2 diabetes results from severe insulin resistance coupled with a failure of β cells to compensate by secreting sufficient insulin. Multiple genetic loci are involved in the development of diabetes, although the effect of each gene on diabetes susceptibility is thought to be small. MicroRNAs (miRNAs) are noncoding 19–22-nucleotide RNA molecules that potentially regulate the expression of thousands of genes. To understand the relationship between miRNA regulation and obesity-induced diabetes, we quantitatively profiled approximately 220 miRNAs in pancreatic islets, adipose tissue, and liver from diabetes-resistant (B6) and diabetes-susceptible (BTBR) mice. More than half of the miRNAs profiled were expressed in all three tissues, with many miRNAs in each tissue showing significant changes in response to genetic obesity. Furthermore, several miRNAs in each tissue were differentially responsive to obesity in B6 versus BTBR mice, suggesting that they may be involved in the pathogenesis of diabetes. In liver there were approximately 40 miRNAs that were downregulated in response to obesity in B6 but not BTBR mice, indicating that genetic differences between the mouse strains play a critical role in miRNA regulation. In order to elucidate the genetic architecture of hepatic miRNA expression, we measured the expression of miRNAs in genetically obese F2 mice. Approximately 10% of the miRNAs measured showed significant linkage (miR-eQTLs), identifying loci that control miRNA abundance. Understanding the influence that obesity and genetics exert on the regulation of miRNA expression will reveal the role miRNAs play in the context of obesity-induced type 2 diabetes. 相似文献
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997.
Tianzhu Zang Bobby W.K. Lee Lisa M. Cannon Kathryn A. Ritter Shujia Dai Dacheng Ren Thomas K. Wood Zhaohui Sunny Zhou 《Bioorganic & medicinal chemistry letters》2009,19(21):6200-6204
Halogenated furanones, a group of natural products initially isolated from marine red algae, are known to inhibit bacterial biofilm formation, swarming, and quorum sensing. However, their molecular targets and the precise mode of action remain elusive. Herein, we show that a naturally occurring brominated furanone covalently modifies and inactivates LuxS (S-ribosylhomocysteine lyase, EC 4.4.1.21), the enzyme which produces autoinducer-2 (AI-2). 相似文献
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999.
Peter D. Burbelo Kathryn H. Ching Caitlin M. Klimavicz Michael J. Iadarola 《Journal of visualized experiments : JoVE》2009,(32)
Technologies for comprehensively understanding and quantifying antibody profiles to autoantigens and infectious agents may yield new insights into disease mechanisms and may elucidate new markers to substratify disease with different clinical features and better understand pathogenesis. We have developed a highly quantitative method called Luciferase Immunoprecipitation Systems (LIPS) for profiling patient sera antibody responses to autoantigens and pathogen antigens associated with infection. Unlike ELISAs, the highly sensitive LIPS is easily implemented to survey humoral serological response profiles to different antigens in a universal format and produces dynamic antibody titer ranges up to 6 log10 for some antigens. In these studies, quantitative profiling by LIPS of patient humoral responses against panels of antigens or even the entire proteome of some pathogens (i.e. HIV), is typically more informative than testing a single antigen by ELISA. In addition, LIPS also eliminates time and effort needed to produce highly purified antigens as well as the labor-intensive assay optimization steps needed for standard ELISAs. Here we provide a detailed protocol describing the technical aspects of performing LIPS assays for readily profiling antibody responses to single or multiple antigens.Download video file.(144M, mp4) 相似文献
1000.