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991.
Kenichiro Shimatani Megumi Kimura Keiko Kitamura Yoshihisa Suyama Yuji Isagi Hisashi Sugita 《Population Ecology》2007,49(4):317-330
In this paper we first mathematically formulate spatial genetic models that rely on dispersal kernels, using the genetic inhomogeneous
Poisson process. On the basis of mapped and genotyped data pertaining to adult and juvenile trees we are able to estimate
three fundamental variables of population dynamics: individual female reproductive success, seed dispersal, and pollen flow.
The model was applied to a secondary Fagus crenata stand in northern Japan, regenerated after shelterwood harvesting. Highly polymorphic microsatellite data revealed that most
of the juveniles around one adult tree were not that tree’s progeny and that some minor alleles were clustered there. These
data suggested that another mother tree had formerly been present in the vicinity, produced offspring there and died. Inferring
its genotype and location, we applied the genetic inhomogeneous Poisson process. Results confirmed that we would have wrongly
assessed the regeneration if we had been unaware of the existence of the dead mother. The average distances for seed dispersal
and pollen flow were 18 and 193 m, respectively. The contribution of outside mothers, simultaneously assessed using the dispersal
variables in the models, ranged from 10 to 50% depending on their positions relative to preserved adults. Individual female
reproductive success varied as much as fiftyfold among the eight preserved adults. Our comprehensive approach, utilizing currently
available genetic information, mathematical models, and previous forestry records, helped elucidation of the past forest-regeneration
processes. 相似文献
992.
A model of cell size regulation 总被引:4,自引:0,他引:4
993.
994.
995.
Isolation of a Ca-dependent erythrolytic protein (perforin) from cytotoxic T-lymphocytes 总被引:1,自引:0,他引:1
A Ca-dependent erythrolytic protein (perforin) was isolated from a cytotoxic T-cell line (CTLL2). Cellular extracts were fractionated on DEAE-cellulose and hydrophobic Phenyl-Sepharose columns. Lytic activity was tightly bound to the hydrophobic column and was eluted with 50% ethyleneglycol. The erythrolytic activity was dependent on the concentration of Ca2+ ions, and heparin accelerated the lysis of erythrocytes by perforin 10-fold, with a half maximal concentration of 12 ng/ml. The activity was strongly inhibited by micromolar concentrations of heavy metal ions, such as Zn2+ and Fe2+, and glycylarginine-methylcoumarinamide (Gly-Arg-MCA) in the presence of 100 ng/ml heparin. 相似文献
996.
Two types of 4,5-dioxovalerate reductases (NADPH) were partiallypurified and characterized from green alga, Chlorella regularis.The enzyme was separated by DEAE-Sephacel chromatography intotwo peaks: type I (first peak) and type II (second peak). Theactivity ratio of the type II to type I enzyme varied between5 to 7 with a starting cell material. Both enzymes had the samepH optimum at 6.0 and pI value of 4.9. The molecular weightestimated by gel filtration was 33,000 for type I and 99,000for type II enzyme. Both enzymes used only NADPH, but were notspecific for 4,5-dioxovaleric acid (DOVA). Type I enzyme reducedglyoxylate 68-fold faster than DOVA, whereas type II enzymeacted more specifically on a variety of aldehydes than DOVA.It is suggested that these enzymes may not function primarilyas NADPH-DOVA reductases in the metabolic pathway of DOVA. (Received June 15, 1985; Accepted October 14, 1985) 相似文献
997.
The enzyme responsible for the succinylleucylleucylvalyltyrosine methylcoumarylamide- (SLLVT-) degrading activity was purified from the postmitochondrial supernatant of rat liver (Yamamoto, T., Nojima, M., Ishiura, S. and Sugita, H. (1986) Biochim. Biophys. Acta 882, 297-304). The enzyme, named ingensin, was activated by saturated fatty acids, especially myristic acid, as well as by unsaturated linoleic acid and arachidonic acid. Although 2-mercaptoethanol activated ingensin 2-fold and p-chloromercuribenzoate and HgCl2 completely inhibited its peptide-hydrolyzing activity, the enzyme is activated by the addition of a thiol-blocking reagent, monoiodoacetic acid. Ingensin was also inhibited by a specific serine proteinase inhibitor, diisopropyl fluorophosphate, but not by a specific cysteine proteinase inhibitor, E-64-c. These results suggest that the enzyme is a serine proteinase with an active thiol group(s) near the active site. We have found that the addition of glycerol and nordihydroguaiaretic acid lowered the extent of its activation by fatty acids as well as its intrinsic peptide-hydrolyzing activity. 相似文献
998.
Purification of the two forms of the high-molecular-weight neutral proteinase ingensin from rat liver 总被引:2,自引:0,他引:2
Two forms of a high-molecular-weight proteinase were isolated from rat liver. The purification procedure involved homogenization of the tissue, chromatography on DEAE-cellulose, high-performance liquid chromatography (HPLC: TSK 3000 SWG) and hydroxyapatite chromatography. The breakthrough fraction from the hydroxyapatite column contained the sodium dodecyl sulphate (SDS)- and linoleic acid-activated proteinase, ingensin A, but the other form, ingensin B, which was also activated by SDS and linoleic acid, was bound to the hydroxyapatite and eluted at 200 mM phosphate. A distinct feature of ingensin A was its activation by a brief sonication procedure. The optimum pH of the two forms was 7.5-9.5, and both of them were activated by monovalent cations. Although both enzymes show similar molecular weights of 700,000 on gel filtration, ingensins A and B were separated into a major subunit of 120,000 and subunits of 25,000-35,000, respectively, under the denaturing conditions. 相似文献
999.
David J. Lakatua Erhard Haus Franz Halberg Erna Halberg Hans W. Wendt Linda L. Sackett-Lundeen Harriet G. Berg Terukazu Kawasaki Michio Ueno Keiko Uezono Midori Matsuoka Teruo Omae 《Chronobiology international》1986,3(3):189-195
Clinically healthy diurnally active young adult women were studied during the same season (March) at the Universities of Kyushu (Fukuoka City, Japan) and of Minnesota (Minneapolis, USA), under comparable conditions, except that the habitual diets were not changed. The subjects (20 Japanese and 16 Americans of mixed Caucasian background) were studied over a single 24-hr span. Urine was collected at 4-hr intervals. A circadian rhythm in total urinary norepinephrine excretion showed similar characteristics in Japanese and Americans. In epinephrine excretion, the Japanese women showed a statistically significantly higher amplitude with higher peak values, but no statistically significant difference in the rhythm-adjusted mean. This intergroup difference is strictly time dependent; it does not come to the fore in urine samples covering the nocturnal rest span of the subjects. 相似文献
1000.
A cytolytic protein (perforin) was rapidly purified from a cell line of mouse cytotoxic T-lymphocytes (CTL) by DEAE-cellulose, heparin-Sepharose, and phenyl-Sepharose chromatographies. The purified perforin was activated by heparin, the half maximal concentration being 3-10 ng/ml, depending on the calcium concentration. Other acid mucopolysaccharides, such as chondroitin sulfates A and C, keratan polysulfate, and heparin sulfate, also enhanced the lysis of erythrocytes by perforin, but the concentrations required for activation were more than 100-fold higher than that of heparin. Chondroitin, hyaluronic acid, and keratan sulfate, however, had no effect on the perforin activity. It was suggested that heparin potentiates the lytic activity of perforin and acid mucopolysaccharides may actually be involved in target cell lysis by CTL. 相似文献