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111.
M E de la Torre A Diaz B Ruiz A Farres C Aramburo S Sanchez 《Journal of industrial microbiology & biotechnology》1996,17(2):73-76
Penicillium candidum grew and produced lipase in a culture medium supplemented with 0.2% olive oil. Significant enzyme production required the presence of olive, oil and was prevented by cycloheximide. Polyacrylamide gel electrophoresis of filtrates from olive oil fermentations gave a single band of lipase activity (MW 80 KDa). Among the olive oil components only oleate allowed significant lipase production. Other carboxylic and saturated fatty acids containing similar or lower numbers of carbon atoms, did not cause derepression of lipase formation. 相似文献
112.
Laetitia C. M. Commandeur Ralph J. May Heinrich Mokross Donna L. Bedard Walter Reineke Harrie A. J. Govers John R. Parsons 《Biodegradation》1996,7(6):435-443
In contrast to the degradation of penta-and hexachlorobiphenyls in chemostat cultures, the metabolism of PCBs by Alcaligenes sp. JB1 was shown to be restricted to PCBs with up to four chlorine substituents in resting-cell assays. Among these, the PCB congeners containing ortho chlorine substituents on both phenyl rings were found to be least degraded. Monochloro-benzoates and dichlorobenzoates were detected as metabolites. Resting cell assays with chlorobenzoates showed that JB1 could metabolize all three monochlorobenzoates and dichlorobenzoates containing only meta and para chlorine substituents, but not dichlorobenzoates possessing an ortho chlorine substituent. In enzyme activity assays, meta cleaving 2,3-dihydroxybiphenyl 1,2-dioxygenase and catechol 2,3-dioxygenase activities were constitutive, whereas benzoate dioxygenase and ortho cleaving catechol 1,2-dioxygenase activities were induced by their substrates. No activity was found for pyrocatechase II, the enzyme that is specific for chlorocatechols. The data suggest that complete mineralization of PCBs with three or more chlorine substituents by Alcaligenes sp. JB1 is unlikely.Abbreviations PCB
polychlorinated biphenyls
- CBA
chlorobenzoate
- D
di
- Tr
tri
- Te
tetra
- Pe
penta-
- H
hexa 相似文献
113.
Pollen allergens interact with the human immune system and the resulting IgE antibodies provide specific probes for their
identification and characterisation. In one case, grass allergenic proteins are expressed late in pollen development coincident
with the laying down of reserves. Sequence similarity of allergens has indicated possible functions for some allergens. The
major birch pollen allergen shows sequence similarity with pathogenesis-related proteins, which form a secondary response
in plant host-pathogen interactions and show anti-microbial activity. Some allergens of unknown function are cysteine-rich
proteins, while some others have cysteine-rich regions; for example, the major allergen from rye-grass pollen, Lol p 1, has
a cysteine-rich N-terminal region, while at the C-terminal region four tryptophan residues together with tyrosine and phenylalanine
residues resemble those of cellulose- or sugar-binding domains of other proteins. Several pollen allergens show sequence similarity
to cell wall-associated enzymes, while others show hydrolytic enzyme activity often associated with cell walls. 相似文献
114.
Expression of a human cytomegalovirus gp58 antigenic domain fused to the hepatitis B virus nucleocapsid protein 总被引:1,自引:0,他引:1
Maryam R. Tarar Vincent C. Emery Tim J. Harrison 《FEMS immunology and medical microbiology》1996,16(3-4):183-192
Abstract Hepatitis B virus core antigen (HBcAg) has been used as a carrier for expression and presentation of a variety of heterologous viral epitopes in particulate form. The aim of this study was to produce hybrid antigens comprising HBcAg and an immunogenic epitope of human cytomegalovirus (HCMV). A direct comparison was made of amino and carboxyl terminal fusions in order to investigate the influence of position of the foreign epitope on hybrid core particle formation, antigenicity and immunogenicity. HCMV DNA encoding a neutralising epitope of the surface glycoprotein gp58 was either inserted at the amino terminus or fused to the truncated carboxyl terminus of HBcAg and expressed in Escherichia coli . The carboxyl terminal fusion (HBc3–144 -HCMV) was expressed at high levels and assembled into core like particles resembling native HBcAg. Protein with a similar fusion at the amino terminus (HCMV-HBc1–183 ) could not be purified or characterised immunologically, although it formed core like particles. HBc3–144 -HCMV displayed HBc antigenicity but HCMV antigenicity could not be detected by radioimmunoassay or western blotting using anti-HCMV monoclonal antibody 7–17 or an anti-HCMV human polyclonal antiserum. Following immunisation of rabbits with HBc3–144 -HCMV, a high titre of anti-HBc specific antibody was produced along with lower titres of HCMV/gp58 specific antibody. 相似文献
115.
CO dehydrogenase/acetyl-CoA synthase (CODH/ACS) is one of the four known nickel enzymes. It is a bifunctional protein that
catalyzes the oxidation of CO to CO2 at a nickel iron-sulfur cluster (Cluster C) and a remarkable condensation reaction between a methyl group (donated from a
methylated corrinoid iron-sulfur protein), carbon monoxide, and coenzyme A to form acetyl-CoA at a separate nickel iron-sulfur
cluster (Cluster A). This review focuses on the current understanding of the structure and function of Cluster A and on related
model chemistry. It describes studies that uncovered the first example of a biological organometallic reaction sequence. The
mechanism of acetyl-CoA synthesis includes enzymebound methylnickel, iron-carbonyl, and acylmetal intermediates. Discovery
of the methylnickel species constituted the first example of an alkylnickel species in biology and unveiled a new biological
role for nickel.
Received: 10 April 1996 / Accepted: 4 July 1996 相似文献
116.
Effect of anoxia and reoxygenation on antioxidant enzyme activities in immortalized brain endothelial cells 总被引:1,自引:0,他引:1
Olivier Rabin Michèle Piciotti Katy Drieu Jean-Marie Bourre Françoise Roux 《In vitro cellular & developmental biology. Animal》1996,32(4):221-224
Summary The effects of anoxia and reoxygenation on major antioxidant enzyme activities were investigatedin vitro in immortalized rat brain endothelial cells (RBE4 cells). A sublethal anoxic period of 12 h was assessed for RBE4 cells using the neutral red uptake test. Anoxia markedly influenced the specific activity of catalase and superoxide dismutase,
with no major effect on glutathione peroxidase or glutathione reductase. After 24 h postanoxia, the superoxide dismutase activity
modulated by the presence or absence of oxygen returned to control value.
Damage and recovery of RBE4 immortalized rat brain endothelial cells in culture after exposure to free radicals and other oxygen-derived species provides
a usefulin vitro model to study anoxia-reoxygenation trauma at the cellular level. 相似文献
117.
Hypoxia Increases the Susceptibility to Oxidant Stress and the Permeability of the Blood-Brain Barrier Endothelial Cell Monolayer 总被引:2,自引:1,他引:1
Monique Plateel Marie-Pierre Dehouck Gérard Torpier †Roméo Cecchelli Elisabeth Teissier 《Journal of neurochemistry》1995,65(5):2138-2145
Abstract: Using a cell culture model of the blood-brain barrier (BBB), we investigated the brain capillary endothelial cell (EC) response to hypoxia. The activities of antioxidant enzymes such as glutathione peroxidase, glutathione reductase, catalase, and superoxide dismutase and the GSH level of brain capillary ECs alone or in coculture with astrocytes, as well as those of pericytes, were compared with those obtained with freshly isolated microvessels. These results demonstrated that brain capillary ECs cocultured with astrocytes and used in the presence of a coculture-conditioned medium provided a relevant in vitro model for studying the effect of hypoxia-reoxygenation at the BBB level. The effect of hypoxia on antioxidant enzymes, GSH, and ATP levels was studied, as well as the modification of the permeability to small weight molecules. A decrease in all enzymes and the GSH level could explain an increase in the susceptibility of the brain capillary ECs to further oxidant injury. Second, profound rearrangements of F-actin filaments of the ECs and a decrease in the ATP level could be associated with an increase in the permeability of the monolayer. Furthermore, an apoptotic process was detected by in situ end labeling of DNA. These results indicate that hypoxia distorts the function of ECs and that these cells in culture provide a valuable tool for exploring mechanisms after hypoxia-reoxygenation. 相似文献
118.
Human Microtubule-Associated Protein-2c Localizes to Dendrites and Axons in Fetal Spinal Motor Neurons 总被引:2,自引:0,他引:2
Joanna S. Albala Yvonne Kress Wan-Kyng Liu Karen Weidenheim Shu-Hui C. Yen Bridget Shafit-Zagardo 《Journal of neurochemistry》1995,64(6):2480-2490
Abstract: Microtubule-associated protein-2 (MAP-2) functions to maintain neuronal morphology by promoting the assembly of microtubules. MAP-2c is an alternately spliced form of MAP-2, containing the first 151 amino acids of high-molecular-weight (HMW) MAP-2 joined to the last 321 amino acids, eliminating 1,352 amino acids specific to HMW MAP-2. A polyclonal antibody generated to the splice site of human MAP-2c was used to determine its cellular localization. The MAP-2c antiserum was depleted of any HMW MAP-2 reactivity by absorption with HMW MAP-2 fusion protein. Western blot analysis of human fetal spinal cord homogenates demonstrated that the antibody is specific for human MAP-2c. MAP-2c immunoreactivity was found in the perinuclear cytoplasm and processes of anterior motor neurons and large processes of the posterior column in sections from 22–24-week human fetal spinal cord. Double-label confocal microscopy was performed using the MAP-2c polyclonal antibody and either a HMW MAP-2 or a neurofilament protein (highly phosphorylated 160- and 200-kDa protein) monoclonal antibody to identify these processes as dendrites or axons, respectively. HMW MAP-2 and MAP-2c colocalized in cell bodies and dendrites of anterior motor neurons, demonstrating for the first time the presence of native MAP-2c within dendrites. In addition, immunoelectron microscopy showed MAP-2c associated with microtubules in dendrites of motor neurons. MAP-2c and the neurofilament proteins were found in axons of the dorsal and ventral roots. The presence of MAP-2c within axons and dendrites suggests that MAP-2c contributes to neuronal plasticity during human fetal development. 相似文献
119.
Localization and activity of three enzymes involved in the amino acid metabolism of ectomycorrhizas were investigated within an interdisciplinary experiment performed in a mature Norway spruce stand in Southern Germany (Höglwald). The enzymes NAD-glutamate dehydrogenase and aspartate aminotransferase were present in root cells, whereas aminopeptidase was found in mycorrhizas of Norway spruce such as Piceirhiza nigra and those with the fungi Cenococcum geophilum, Elaphomyces sp., Russula ochroleuca and Tylospora sp. Mycorrhizas growing in the humus layer contained about double the amount of protein found in those taken from the upper mineral soil (0–5 cm).Acid irrigation of the soil had no effect on the activity of any of the investigated enzymes, soluble protein or total N-contents irrespective of whether roots were taken from the organic layer or from the upper mineral soil. Liming, however, stimulated the activity of the three enzymes in mycorrhizas of the organic layer (Of+Oh) whereas it had no effect on the activity of the investigated enzymes of mycorrhizas in the upper mineral soil. This effect is attributed to increased contents of soluble organic nitrogen compounds in the soil of the limed plots as compared to the unlimed plots. 相似文献
120.
N-terminal sequence analysis of atrial granule serine proteinase purified by affinity chromatography
Atrial granule serine proteinase is considered the leading candidate endoproteolytic processing enzyme of pro-atrial natriuretic factor. Its cleavage specificity is directed toward a monobasic amino acid processing site, and as such, the atrial enzyme is distinguished from the family of prohormone convertases which act at dibasic amino acid processing sites. To delineate the molecular mechanisms which distinguish monobasic from dibasic amino acid-directed processing enzymes, pure atrial enzyme is needed for sequence determination leading to molecular cloning, and for preparation of antisera. An affinity chromatography purification scheme seemed a logical modification of our established procedures to yield suitable amounts of enzyme for further studies. Surprisingly, pseudo-peptide bond inhibitors of the atrial enzyme [Damodaran and Harris (1995),J. Protein Chem., this issue] formed ineffective affinity ligands, even though these compounds contain essential residues on either side of what would be the scissile bond in a peptide substrate. On the other hand, tripeptide aldehydes (based on the substrate recognition sequence of the atrial enzyme) linked to Sepharose formed effective affinity matrices, permitting purification of the enzyme in a single step from a subcellular fraction enriched for atrial granules and lysosomes. Hence, the enzyme was purified 2000-fold in 90% overall yield, and subjected to N-terminal sequence analysis through 26 residues. The sequence determined, XXPEAAGLPG[R, L]GNPVP[F, G]R[Q, I]XY[G, E]XR(N, A]V, indicates that the atrial enzyme is unique, showing little sequence homology to other proteins in the database.Abbreviations AGSP
atrial granule serine proteinase
- ANF
atrial natriuretic factor
- BSA
bovine serum albumin
-
Bz
benzoyl
- EACA
6()-aminocaproic acid
- HEPES
N-2-hydroxyethylpiperazine-N'-propanesulfonic acid
- HPLC
high-performance liquid chromatography
- PEG
polyethylene glycol-3350
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Single-letter abbreviations are used to denote amino acids 相似文献