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101.
Philip G. Penketh Krishnamurthy Shyam Raymond P. Baumann Rui Zhu Kimiko Ishiguro Alan C. Sartorelli Elena S. Ratner 《Analytical biochemistry》2016
Alkylating agents are a significant class of environmental carcinogens as well as commonly used anticancer therapeutics. Traditional alkylating activity assays have utilized the colorimetric reagent 4-(4-nitrobenzyl)pyridine (4NBP). However, 4NBP based assays have a relatively low sensitivity towards harder, more oxophilic alkylating species and are not well suited for the identification of the trapped alkyl moiety due to adduct instability. Herein we describe a method using water as the trapping agent which permits the trapping of simple alkylating electrophiles with a comparatively wide range of softness/hardness and permits the identification of donated simple alkyl moieties. 相似文献
102.
Background
Computerized adaptive testing (CAT) utilizes latent variable measurement model parameters that are typically assumed to be equivalently applicable to all people. Biased latent variable scores may be obtained in samples that are heterogeneous with respect to a specified measurement model. We examined the implications of sample heterogeneity with respect to CAT-predicted patient-reported outcomes (PRO) scores for the measurement of pain.Methods
A latent variable mixture modeling (LVMM) analysis was conducted using data collected from a heterogeneous sample of people in British Columbia, Canada, who were administered the 36 pain domain items of the CAT-5D-QOL. The fitted LVMM was then used to produce data for a simulation analysis. We evaluated bias by comparing the referent PRO scores of the LVMM with PRO scores predicted by a “conventional” CAT (ignoring heterogeneity) and a LVMM-based “mixture” CAT (accommodating heterogeneity).Results
The LVMM analysis indicated support for three latent classes with class proportions of 0.25, 0.30 and 0.45, which suggests that the sample was heterogeneous. The simulation analyses revealed differences between the referent PRO scores and the PRO scores produced by the “conventional” CAT. The “mixture” CAT produced PRO scores that were nearly equivalent to the referent scores.Conclusion
Bias in PRO scores based on latent variable models may result when population heterogeneity is ignored. Improved accuracy could be obtained by using CATs that are parameterized using LVMM. 相似文献103.
G V Abramochkin E N Ratner V V Petrov A I Severin N E Suzina B A Fikhte I S Kulaev 《Prikladnaia biokhimiia i mikrobiologiia》1990,26(1):93-100
The effect of the bacteriolytic preparation "Lysoamidase" on Staphylococcus aureus 299 P was studied. The maximum activity of the preparation was observed at pH 8.0 ionic strength 0.01-0.02 M and 50-60 degrees of the incubation medium. The electron microscopic examination revealed that "Lysoamidase" hydrolyzed the cell wall in one or several points with the following osmotic shock and extrusion of the cytoplasm. In an isotonic solution (1 M sucrose) "Lysoamidase" caused protoplast formation. 相似文献
104.
A. Ratner M.C. Wilson L. Srivastava G.T. Peake 《Prostaglandins & other lipid mediators》1974,5(2):165-171
The effect of prostaglandin E1 (PGE1) on rat anterior pituitary cyclic AMP accumulation and luteinizing hormone (LH) release was studied both in vivo and in vitro. Addition of PGE1 to incubation medium over a concentration range of 10-6 to 10-4 M produced a graded increase in pituitary cyclic AMP. At the lowest concentration (10-6 M) there was no significant increase in LH release, but proportional increments in LH release were seen with increasing concentrations of PGE1.Ten minutes after intravenous administration of 5 μg of PGE1 to adult male rats, pituitary cyclic AMP was substantially increased while serum LH levels were not changed. Administration of a higher dose of PGE1 (20 μg) produced a greater increase in pituitary cyclic AMP; and, at this dose serum LH was significantly increased. These results suggest that the PGE1 effect on LH release is mediated by the adenyl cyclase — cyclic AMP system. 相似文献
105.
The interaction bacterial and phage proteins with immobilized Escherichia coli RNA polymerase 总被引:20,自引:0,他引:20
D Ratner 《Journal of molecular biology》1974,88(2):373-383
106.
D B Yelvington M J Rosenthal A Ratner 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1987,184(2):239-242
The corticosterone (CORT) and prolactin (PRL) responses to 1.0 mA of footshock were measured in healthy rats and rats with pneumonia. No differences in basal PRL levels were seen, but basal CORT levels were significantly increased in the sick animals. Healthy rats showed a significant increase in both PRL and CORT after receiving footshock whereas the sick rats showed no changes. The adapative value of the current findings are unclear at this time. 相似文献
107.
Specific asparagine-linked oligosaccharides are not required for certain neuron-neuron and neuron-Schwann cell interactions 总被引:7,自引:3,他引:4
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N Ratner A Elbein M B Bunge S Porter R P Bunge L Glaser 《The Journal of cell biology》1986,103(1):159-170
To determine whether specific asparagine-linked (N-linked) oligosaccharides present in cell surface glycoproteins are required for cell-cell interactions within the peripheral nervous system, we have used castanospermine to inhibit maturation of N-linked sugars in cell cultures of neurons or neurons plus Schwann cells. Maximally 10-15% of the N-linked oligosaccharides on neuronal proteins have normal structure when cells are cultured in the presence of 250 micrograms/ml castanospermine; the remaining oligosaccharides are present as immature carbohydrate chains not normally found in these glycoproteins. Although cultures were treated for 2 wk with castanospermine, cells always remained viable and appeared healthy. We have analyzed several biological responses of embryonic dorsal root ganglion neurons, with or without added purified populations of Schwann cells, in the presence of castanospermine. We have observed that a normal complement of mature, N-linked sugars are not required for neurite outgrowth, neuron-Schwann cell adhesion, neuron-induced Schwann cell proliferation, or ensheathment of neurites by Schwann cells. Treatment of neuronal cultures with castanospermine increases the propensity of neurites to fasciculate. Extracellular matrix deposition by Schwann cells and myelination of neurons by Schwann cells are greatly diminished in the presence of castanospermine as assayed by electron microscopy and immunocytochemistry, suggesting that specific N-linked oligosaccharides are required for the expression of these cellular functions. 相似文献
108.
The resistance to freezing-thawing was studied with Cryptococcus laurentii cultivated at a near-zero plus temperatures in a minimal or a rich medium. At the transition into the stationary phase, the resistance of the cells to freezing increased 20 times in the culture grown in the minimal medium and 8 times in the culture grown in the rich medium. Free water localization in the cell cytoplasm was determined by electron microscopy. In yeast cells with the maximal cryotolerance, free water was found mainly between glycogen granules. The authors discuss the role of glycogen as of a possible factor making the cells resistant to low temperatures. 相似文献
109.
110.
The drawing of blood by orbital sinus puncture (OSP) under ether anesthesia is known to produce a marked increase in serum prolactin (PRL levels in young cycling female rats. The effect of this stressful procedure on PRL release was compared in young and aged female rats. Nonstressed PRL levels were obtained from blood drawn by decapitation. Whereas OSP with a one-minute ether exposure induced a marked increase in PRL levels in young rats on all days of the estrus cycle, older cycling female rats on the day of diestrus -1 and aged rats exhibiting prolonged diestrus (PD) showed virtually no increase above nonstressed levels. However, increasing the ether exposure time to five minutes did produce a rise in PRL levels. Old cycling female rats on the day of estrus and aged rats exhibiting constant estrus (CE) did show a PRL increase comparable to that seen in young animals. Ovariectomy (OVX) completely abolished the stress response seen in aged CE rats. The response, though markedly decreased, was still present in young ovariectomized rats. These experiments show that the stress-induced rise in PRL promoted by OSP under either anesthesia is markedly diminished in aged rats exhibiting a diestrus state. The attenuated response seen in these rats is believed due to factors characteristic of the diestrous state of aging. 相似文献