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51.
Marc van Bilsen Wim Engels Ger J. van der Vusse Robert S. Reneman 《Molecular and cellular biochemistry》1989,88(1-2):113-121
Summary The precise role of eicosanoids in the development of myocardial injury during ischemia and reperfusion is still a matter of debate. Enhanced local production of these bioactive compounds appears to be a common response to tissue injury. Most likely, the cardiac tissue has the capacity to generate prostaglandins, thromboxanes as well as leukotrienes. Prostacyclin (PGI,) is the major eicosanoid produced by the jeopardized myocardium. In addition, at sites of tissue injury activation of platelets and infiltrating leukocytes results in the formation of considerable amounts of thromboxanes and leukotrienes. The production of eicosanoids requires prior release of arachidonic acid (AA) from phospholipids. Both ischemia and reperfusion are associated with a rise in the tissue level of AA. The absence of a proportional relationship between the tissue level of AA and the amounts of PGI, produced suggests that the sites of AA accumulation and PGI2 formation are different. It is conceivable that AA accumulation is mainly confined to myocytes, whereas the capacity to synthesize PGI, mainly resides in vascular cells. Both beneficial and detrimental effects of eicosanoids on cardiac tissue have been described. Prostaglandins act as vasodilators. Besides, some of the prostaglandins, especially PGI,, are thought to possess cyto-protective properties. Thromboxanes and leukotrienes may impede blood supply by increasing smooth muscle tone. Besides, leukotrienes augment vascular permeability. Experimental studies, designed to evaluate the effect of pharmacological agents, like PGI2-analogues and lipoxygenase and cyclo-oxygenase inhibitors, indicat that eicosanoids influence the outcome of myocardial injury. However, the delineation of the physiological significance of the locally produced eicosanoids is complicated by such factors as the wide variety of AA derivatives produced and the dose-dependency of their effects. 相似文献
52.
Florence Levy-Favatier Lydie Tichnonicky Jacques Kruh Marc Delpech 《Biochimie》1989,71(11-12):1157-1161
We have previously described in rat liver two protein kinases tightly bound to DNA, one is serine-specific, the other arginine-specific. In this work we show that both enzymes are present in various rat tissues and in liver from various species. Both kinase specific activities are strongly decreased in methyl-DBA-induced hepatomas and in HTC cells but not in regenerating liver after hepatectomy. This decrease is then not related to cell proliferation. 相似文献
53.
Actinomycetes were isolated from the upper 1 - 3 cm of the soil layer in a well-developed forest and in an adjacent clearcut
area where Douglas-fir [Pseudotsuga menziesii (MIRB.) Franco] regeneration had been impaired for two decades. The population density in the clearcut area was two times
as high as that in the forested area. The percentage of actinomycetes that inhibited seed germination of the test plants was
significantly higher in isolates obtained from the clearcut area than in those obtained from the forested area, and isolates
from the clearcut showed five times the phytotoxic effect of those from the forest. Some actinomycete isolates, 4 % from the
clearcut and 2.6 % from the forest, significantly reduced in vitro growth of two common ectomycorrhizal fungi of Douglas-fir,Laccaria laccata andHebeloma ovstuliniforme. Two actinomycete isolates from the clearcut reduced fungal growth by 40 % and 73 %. Reduction of the nutrient in the growth
medium did not affect the antifungal activity of the actinomycetes. The data support the idea that, along with other factors,
phytotoxic and antifungal actinomycetes may suppress natural regeneration or establishment of planted seedlings - either directly
or. indirectly - through inhibition of seed germination or of mycorrhizal fungi. 相似文献
54.
Basic and acidic fibroblast growth factors modulate the epidermal growth factor receptor by a protein kinase C-independent pathway 总被引:2,自引:0,他引:2
K Hicks B Friedman M R Rosner 《Biochemical and biophysical research communications》1989,164(2):796-803
Human acidic and basic fibroblast growth factors (aFGF and bFGF) inhibit epidermal growth factor (EGF) receptor binding in mouse Swiss 3T3 cells. Scatchard analysis indicates that aFGF and bFGF cause a decrease in the high affinity EGF receptor population, similar to that observed for activators of protein kinase C such as phorbol esters, platelet-derived growth factor (PDGF) and bombesin. However, unlike phorbol esters, aFGF and bFGF inhibit EGF binding in protein kinase C-deficient cells. The time course and dose response of inhibition of EGF binding by both aFGF and bFGF are very similar, with an ID50 of approximately 0.10 ng/ml. In contrast to bombesin but like PDGF, neither aFGF nor bFGF act on the EGF receptor through a pertussis toxin-sensitive G protein. These results indicate that both acidic and basic FGF depress high affinity EGF binding in Swiss 3T3 cells with similar potency through a protein kinase C/Gi-independent pathway. 相似文献
55.
Marc E. Savard J. David Miller Baharuddin Salleh Richard N. Strange 《Mycopathologia》1990,110(3):177-181
Extracts of rice on which an isolate of Fusarium chlamydosporum had been cultured were toxic to brine shrimps. The toxic fraction was purified by flash chromatography to give two compounds which were identified by UV, IR, NMR and mass spectroscopy at the 6 and 6 isomers of 5-hydroxy-4-methoxy-6, 8a-dimethyl-6,7-dihydro-2H,8aH-pyrano[2,3-b]pyran-2-one. These lactones for which the name chlamydosporol is proposed have not been reported previously. When tested in brine shrimp and HeLa cell assays, the LC50 concentration for a mixture of the isomers was approximately 400 g/ml in both systems. 相似文献
56.
Summary Non-histone chromatin protein (NHCP) fractions were extracted from purified beef thyroid nuclear preparations and tested for the presence of protein kinase activities using several known mediators of thyroid regulation, as well as potential phosphotransferase substrates using purified or partially purified protein kinase activities. The addition of cAMP/3-isobutyl-l-methylxanthine had no effect on NHCP historic kinase activity; the addition of 10 g of the heat-stable cAMP-dependent protein kinase A inhibitor, however, resulted in a 47% reduction in histone H2 kinase activity. Nuclear casein kinase II activity was present in the NHCP fractions as evidenced by the capacity of spermine to stimulate (ED50 = 0.19 mM) and heparin to inhibit (ID50 = 0.09 g/ml) the phosphorylation of casein; further, the phosphotransferase activity could be purified by sequential casein-agarose and spermine-agarose affinity chromatography. Neither calcium-calmodulin nor calcium/phosphatidylserine/diolein had an effect on NHCP casein kinase or histone kinase activities, respectively. The addition of cAMP-dependent protein kinase A catalytic subunit, nuclear casein kinase II, calcium-activated calmodulin-dependent protein kinase and diacylglycerol-activated calcium/phospholipid-dependent protein kinase C activities exhibited distinct phosphorylation patterns when NHCP were used as substrates and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography. We conclude that NHCP fraction from beef thyroid: 1) contains both cAMP-dependent protein kinase A catalytic subunit and nuclear casein kinase II and 2) substrates for cAMP-dependent protein kinase A, calcium-activited calmodulin-dependent protein kinase, protein kinase C, and nuclear casein kinase II.Abbreviations NHCP
Non-Histone Chromatin Proteins
- PK-A
cAMP-Dependent Protein Kinase
- CAMPK
Calcium-Activated Calmodulin-Dependent Protein Kinase
- PK-C
Diacylglycerol-Activated Calcium/phospholipid-dependent Protein Kinase
- NK-11
Nuclear Casein Kinase 11
- CK-G
Cytosolic Casein Kinase G or 11
- PMSF
Phenylmethyl Sulfonyl Fluoride
- PKI
the Heat Stable PK-A Inhibitor (Walsh inhibitor)
- SDS-PAGE
Sodium Dodecylsulfate Polyacrylamide Gel Electrophoresis
- EDTA
Ethylenediamine Tetraacetic Acid
- EGTA
Ethyleneglycol bis- (B-aminoethyl ether) N,N,N,N,-Tetraacetic Acid
- PS
Phosphatidylserine
- DO
1,2-Diolein 相似文献
57.
I. Lerer S. Cohen M. Chemke A. Sanilevich J. Rivlin A. Golan J. Yahav A. Friedman D. Abeliovich 《Human genetics》1990,85(4):416-417
Summary We have analysed the distribution of the ΔF508 mutation and the haplotypes of cystic fibrosis (CF) bearing chromosomes among
the Israeli CF population. The population was classified according to its ethnic origin and included 3 groups, Ashkenazi Jews,
Sephardic/Oriental Jews and Arabs. Haplotype B (KM19 allele 2, XV2c allele 1) was found to be the predominant haplotype in
all groups but in each of them the haplotype distribution was different. The ΔF508 mutation was present in all groups and
accounts for 32% of the CF mutations. It was mainly associated with the B haplotype but only one third of the CF chromosomes
with this haplotype carry the ΔF508 mutation.
This work is dedicated to Dr. Ruth Voss who initiated the CF study in Israel and was tragically killed in a car accident on
7 August 1988 相似文献
58.
On the evolutionary ecology of marking pheromones 总被引:5,自引:0,他引:5
Summary Many parasitic insects mark hosts with a pheromone after oviposition. The evolutionary ecology of such marking pheromones was studied to determine (i) under what ecological and behavioral conditions such pheromones could evolve and (ii) why so many of these marking pheromones are water-soluble and thus short-lived. We used a number of different techniques. First, the fitness values of individual normal (nonmarking) and mutant (marking) insects foraging for hosts were computed using dynamic state-variable models. Second, population level models were used to study when a population of non-marking individuals can be invaded by marking individuals. Third, behavior-rich simulations (developed originally for apple maggot,Rhagoletis pomonella) were used to test experimentally some of the hypotheses generated using the individual and population-level models. Finally, we developed a model for the benefit over time to an individual by marking. This model shows that when benefit is measured in terms of larval survival, nearly all of the benefit to a mother is obtained from short-lived marks. Genetical theories of pheromone evolution and the connection between our results and existing theories of altruistic behavior are discussed. 相似文献
59.
60.