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1.
Abstract. Although the oesophageal appendages in the four enchytraeids Enchytrueus crypticus, Fredericia strinta, Buchholzia appendiculata , and Achaeta sp. are quite different from one another in shape and position, their histology and ultrastructure are basically the same. These are intestinal appendages, the lumina of which distally end blind and proximally open into the oesophagus. Almost all of the few cells in their single-layered epithelium have a microvillous, cilia-free border at the apex, facing towards the lumen, and basally comprise an extremely extensive labyrinth. The presence of the latter, composed of very thin cell processes, and of numerous mitochondria identifies the organs as energy-producing and -consuming, transport-active structures. Their possible function as a food-moistening organ or osmoregulatory organ is discussed, and they are compared with other intestinal appendages in enchytraeids and other oligochaetes. 相似文献
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G. Renner 《Life sciences》1983,33(14):1427-1431
Studies on the biotransformation of N-acetyl-S-(pentachlorophenyl) cysteine, a mutual polar metabolite of the lipophilic fungicides pentachloronitrobenzene and hexachlorobenzene, showed metabolic conversions in rats. The rate of its metabolism, leading in return to more lipophilic and toxic products (1) was investigated by determination of pentachlorothioanisole, its major metabolite in blood and liver of rats. The metabolic rate was found to be very small. 相似文献
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Wm. Renner 《BMJ (Clinical research ed.)》1911,1(2611):110-111
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Wilfried Stubbe 《Molecular & general genetics : MGG》1953,85(2):180-209
Ohne ZusammenfassungMit 7 Textabbildungen.In ausführlicherer Form und mit zahlreichen Abbildungen als Dissertation bei der Naturwissenschaftlichen Fakultät der Universität München eingereicht. 相似文献
8.
Photoautotrophic cell suspension cultures of Chenopodium rubrumrequire high concentrations of nitrate and ammonium. Duringthe growth phase total NH4+ and the greater portion of NH3were consumed. During the stationary phase nitrate uptake continuedbut at a substantially smaller rate than during the growth phase.During growth the bulk of the absorbed N was incorporated intoprotein, the amount of which was then maintained constant untilsenescence. NH3 was accumulated upon transition betweenthe growth and the stationary phase. NH3, like the freeamino acids, was deposited in the vacuole but, unlike thesecompounds, could not be remobilized upon transfer of the cellsinto N-free medium. Readdition of NH4+ to the medium, however,resulted in a mobilization of the vacuolar NH3-pool.Reutilization of both vacuolar N-storage pools must have beenaccomplished by recycling from the vacuole to the cytoplasmbecause N-metabolizing enzymes could not be detected in isolatedvacuoles. Transfer of the cells of the stationary phase intomedium containing NH3 and NH4+ resulted in an inductionof nitrate uptake by the cells, but only after a lag phase of45 days. It is conceivable that NH4+ induces NH3-translocatingsystems in the plasmalemma and in the tonoplast. (Received December 19, 1988; Accepted March 2, 1989) 相似文献
9.
Jackie R. Vandenheede Sigrid Staquet Wilfried Merlevede 《Molecular and cellular biochemistry》1989,87(1):31-39
Summary Fractionation of rabbit skeletal muscle cytosol on Aminohexyl-Sepharose has resulted in the identification of a latent ATP, Mg-dependent protein phosphatase whose catalytic subunit is in the active conformation, but is inhibited by the presence of more than one modulator unit. The partially purified enzyme is converted to an inactive, kinase FA-dependent form upon incubation at 30°C unless modulator-specific polyclonal antibodies are added to the preparation. The immunoglobulins also relieve the inhibition which is responsible for the low basal phosphatase activity of the enzyme, and they counteract all of the heat-stable inhibitor activity present in the preparation. Addition of free catalytic subunit abolishes the inhibition of the latent enzyme in a dose-dependent way, but cannot prevent the inactivation process. The inactivated phosphatase and the original latent enzyme exhibit the same apparent M
r in sucrose density-gradient centrifugation (70 000) and in gel filtration (110 000).Abbreviations PMSF
Phenylmethanesulphonyl Fluoride
- TLCK
L-l-chloro-3-(4-tosylamido)-7-amino2-heptanone-hydrochloride
- TPCK
L-l-chloro-3-(4-tosvlamido)-4-phenyl-2-butanone 相似文献
10.
Plasmalemma-rich microsomal vesicles were prepared from whole leaf and acid-washed epidermal tissue of Vicia faba L. cv. Osnabrücker Markt by aqueous two-phase partitioning in dextran T-500 and polyethylenglycol 1350 aqueous phases. These vesicles were tightly sealed and predominantly right-side out, and contained a K+ -stimulated, mg2+-dependent and vanadate-sensitive ATPase. The enzyme from both tissues exhibited nearly identical properties: pH optimum 6.4, Km for ATP 0.60 mM(whole leaf) and 0.67 mM (epidermis). Vmax -480 nmol (mg protein)1 min1 (whole leaf) and 510 nmol (mg protein)1 min1 (epidermis), I50 (Na3,VO4) 7.5 μM (whole leaf) and 15 μM (epidermis). The enzyme was not inhibited by NO3(50 mM)or sodium azide (I mM). DCCD (20 μM) reduced enzyme activity to 50% (whole leaf) and 58% (epidermis), gramicidin S (20 μM) to 36% (whole leaf) and 41%(epidermis). Ca2+ inhibited the ATPase [I50, C2+: 0.5 mM(whole leaf) and 0.8 mM(epidermis)]. Ca2+ inhibited the ATPase [I50, C2+ 0.5 mM(whole leaf) und 0.8 (epidermis)]. The vanadate-sensitive ATPase from whole leaf and epidermal tissue was slightly but significantly stimulated by fusicoccin (FC) at a concentration (0.13 μM) promoting stomatal opening. The stimulation was not seen in the solubilized ATPase. Stomata of the cultivar used here were insensitive lo (±)ABA up to 2 μM level which is effective in most other cultivars and species. Likewise, at this concentration no effect of ABA on the activity of the epidermal ATPase was observed. The data are discussed with respect to the interaction of FC and ABA with the ATPase. 相似文献