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61.
Homonuclear two-dimensional (J, delta) proton spectroscopy has been suggested as a method for the measurement of 1H-31P coupling constants in oligonucleotides. The technique has been applied to a dinucleoside monophosphate G2'p5'C and a deoxydecanucleotide d(ACATCGATGT). PCILO energy calculations have been carried out to find minimum energy conformations with respect to the DNA backbone torsion angle epsilon, and these have been considered for the interpretation of the observed H3'-31P coupling constants in oligonucleotides. 相似文献
62.
Visualization and solubilization of rat brain opiate receptors with a “κ” ligand selectivity pattern 总被引:2,自引:0,他引:2
Remi Quirion Wayne D. Bowen Miles Herkenham Candace B. Pert 《Cellular and molecular neurobiology》1982,2(4):333-346
1. Specific binding of [3H]ethylketocyclazocine (EkappaC), a prototype kappa-opiate agonist, to slide-mounted rat striatal sections is increased in the presence of 100 mM NaCl at 4 degrees C. 2. Under similar incubation conditions, binding of mu and delta prototype opiates is reduced to almost undetectable levels. 3. Correlation (P less than 0.01) of the ligand selectivity pattern of [3H]EKC displacement with the potencies of various opiate drugs in inhibiting the contractions of the rabbit vas deferens, a kappa-opiate receptor bioassay, suggests that the binding site under study represents the pharmacologically relevant kappa-opiate receptor. 4. Visualization of these kappa-opiate receptors with tritium-sensitive film reveals a striking, highly discrete brain distribution pattern (e.g., striatal patches, habenular stripe) which is similar to that of [3H]dihydromorphine and [3H]naloxone. 5. Soluble [3H]EKC binding sites obtained from rat membranes also possess a kappa-like ligand selectivity pattern, with bremazocine being a potent displacer while mu and delta ligands are almost inactive. 6. A possible explanation of these data is that the "kappa"-opiate binding site in rat brain is one transitional state of an opiate receptor capable of assuming distinct conformations with characteristic ligand selectivity patterns. Other possibilities such as pre and post-synaptic locations should also be considered. 相似文献
63.
Soil Cd addition was found to adversely affect germination ofAndropogon scoparius, Monarda fistulosa, andRudbeckia hirta. Rudbeckia germination was found to be most sensitive to soil Cd addition andAndropogon germination most tolerant (b=–.0001). Soil cadmium concentrations sufficient to reduce germination by 25% were calculated to be 30 and 46 g Cd/g soil forRudbeckia andAndropogon respectively.Contribution from Purdue University Agricultural Experiment Station, West Lafayette, Indiana 47907. AES Journal No. 7594. This work was supported by federal funds from the National Science Foundation — RANN Program. 相似文献
64.
Miles CD 《Plant physiology》1976,57(2):284-285
Resistance of a seedling to the herbicide 1,1′-ethylene-2,2′-dipyridylium bromide (diquat) can be used as a selective technique for photosynthesis mutants in Zea mays L. Diquat requires reduction by the light reaction in order to kill leaf cells and, therefore, nonphotosynthetic mutants survive. This technique was tested using known mutants and is applicable to larger samples of plants than previous techniques. Resistance to diquat should allow selection of mutants on the oxidizing side of photosystem II which are not previously available in higher plants. 相似文献
65.
The thermal stability of a new polynucleotide complex has been used to establish the hydrogen-bonding structure of three-stranded C-G·CH+ helices. In the Hoogsteen structure, the 8NH2 group of 8NH2GMP can form a third hydrogen bond to the CH+ strand, but in the alternative structure, the 8NH2 group can form no interbase hydrogen bonds. For the new complex, 8NH2GMP·2 poly(C), a transition temperature of 80°C is observed under conditions in which the corresponding complex formed with 5′-GMP has a Tm of 20°C. We conclude from this 60° elevation of transition temperature that a third hydrogen bond is formed by the 8NH2 group and that the structure must have Hoogsteen bonding. In order to be compatible with this structure in regular helices formed by U,C copolymers, A·2U bonding would also have to have a Hoogsteen structure. 相似文献
66.
E W Miles 《Biochemical and biophysical research communications》1975,64(1):248-255
α-Cyanoglycine inactivates the pyridoxal-P forms of the β2 subunit and the α2β2 complex of tryptophan synthase; an intense chromophore at 430 nm forms concomitantly. The slow reactivation of the modified β2 subunit upon dialysis () is prevented by addition of α subunit, which presumably acts by changing the environment of the chromophoric derivative. These data and the observed protection from inhibition by L-serine indicate that α-cyanoglycine acts as a substrate analog which undergoes a second, largely irreversible reaction at the active site of the β2 subunit. Modification of the β2 subunit increases its affinity for the α subunit. Modification of the α2β2 complex increases its stability to heat, urea, and low pH. 相似文献
67.
68.
Miles B Markus 《BMJ (Clinical research ed.)》1985,290(6481):1592
69.
Study of the interaction of Saccharomyces cerevisiae with glucose by particle microelectrophoresis 总被引:1,自引:0,他引:1
Saccharomyces cerevisiae NCYC 239 in the presence of glucose at temperatures under 303 K shows a time-dependent lowering of electrophoreric mobility v. At temperatures above 303 K, this time-dependent change in v is in the direction of increased mobilities. Cells suspended in buffer indicate a surface pKa of less than 4, whereas for cells suspended in buffered glucose it is impossible to derive a surface pKa. A kinetic study of the interaction of S. cerevisiae with glucose as a function of temperature allows calculation of an activation energy of 140 kJ X mol-1 for the combined processes of (i) uptake of glucose onto the cell wall, (ii) transfer through the cell wall and membrane, and (iii) the establishment of a steady glucose flux through the wall and membrane. 相似文献
70.