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981.
982.
Structural requirements of polynucleotides for the activation of (2'' - 5'')An polymerase and protein kinase. 总被引:2,自引:0,他引:2 下载免费PDF全文
Two enzymatic pathways are involved in the inhibitory effects of double-stranded (ds)RNA on protein synthesis in cell extracts derived from interferon-treated human fibroblasts or HeLa cells, an oligonucleotide polymerase that synthesizes (2'-5')An from ATP and a protein kinase that phosphorylates the alpha subunit of initiation factor eIF-2 as well as a polypeptide of Mr = 72,000. We have now evaluated the activation of both the (2'-5')An polymerase and protein kinase by a large variety of polynucleotides, triple-stranded and synthetic dsRNAs, homopolymers, alternating copolymers, triple-stranded polymers, purine-purine duplexes and purine-pyrimidine duplexes with modifications at either the pyrimidine or ribose moieties. All these polynucleotides have been the subject of previous interferon induction studies. Some polynucleotides, i.e. (I)n.(C)n and mycophage dsRNA, which have been recognized as excellent interferon inducers, were also potent activators of both (2'-5')An polymerase and protein kinase, whereas non-inducers such as (A)n. (X)n and (A)n. (br5U)n did not activate either the kinase or the polymerase. However, some polymers like (I)n.(br5C)n, (difl)n(C)n and (dIcl)n (C)n, while potent interferon inducers and kinase activators, behaved poorly as activators of the (2'-5')An polymerase. Other polymers, i.e. (dAfl)n (U)n and (A)n.(U)nl (I)n, that do not induce interferon, activated the kinase but not the polymerase. Finally, (I)n (s2c)n, a relatively potent interferon inducer, did not activate either kinase or polymerase. These findings indicate that there is no simple relationship between the interferon-inducing ability of dsRNAs and their stimulating effects on (2'-5')An polymerase and protein kinase activity. 相似文献
983.
Riccardo Cerri Francesco De Simone Felice Senatore 《Biochemical Systematics and Ecology》1981,9(4):247-248
The sterol composition of three fungi was determined. Ergosterol is the major sterol, accompanied by other closely related sterols. 相似文献
984.
An outbreak of bacillary dysentery in 1978 affecting 928 persons, most of whom were living in the village of St-Jacques, PQ, is described. An epidemiologic study suggested the water supply as the source of the infection, and it was established that the water carried by the municipal aqueduct was contaminated by feces containing the causal agent, Shigella sonnei. This epidemic, the largest mentioned in he Canadian medical literature, demonstrates how contagious this infection is. 相似文献
985.
J J Cassiman E De Clercq A S Jones R T Walker H Van den Berghe 《BMJ (Clinical research ed.)》1981,283(6295):817-818
The rate of sister chromatid exchange induced by several anti-herpes agents was measured to assess their potential mutagenicity. The agents--5-iodo-deoxyuridine (IDU), 5-trifluoromethyl-deoxyuridine (TFT), and [E]-5-(2-bromovinyl)-deoxyuridine (BVDU)--were incubated at various concentrations with human lymphocytes and fibroblasts, and that rate of sister chromatid exchanges was measured. In lymphocytes and fibroblasts BVDU and IDU did not induce exchange except at concentrations of 50 mg/l, while TFT increased the rate of exchange at a concentration of 0.5 mg/l. The rate of sister chromatid exchange is a sensitive index of chromosomal damage, and these findings provide information on the safety of some of the antiherpes agents tested. TFT increased the rate of exchange at a concentration that coincides with its minimal antiviral concentration, but BVDU did not induce exchange at therapeutic concentrations. 相似文献
986.
Leon R. Kass 《In vitro cellular & developmental biology. Plant》1981,17(12):1091-1099
Summary Modern science, dedicated since its 17th Century origins to the mastery and possession of nature for the relief of man's estate,
is a source of great social change, affecting our opinions, practices, and ways of life. It thus exists necessarily in tension
with law and morality, our institutions of stability and order. This tension between change and permanence, between science
and law or morals, was institutionalized by the American Founders who sought to encourage, under law, the progress in science
and the useful arts, by means of the copyright and patent laws. American science and technology have flourished under the
patent law, an ingenious ethical and social contract between scientists and the polity, through which private right and interest
and public good generally coincide. Nevertheless, this contract has its limitations. Some of these limitations are vividly
seen through the recent Supreme Court decision (in the Chakrabarty case) to permit the patenting of living microorganisms.
Analysis of this case shows why the contract between science and the polity embodied in the Patent Laws may not always serve
the public good and may also be harmful to science itself. Also, permitting ownership of living species shows how close we
have come in our thinking to overstepping the sensible limits of the project for the mastery and possession of nature. 相似文献
987.
988.
A reliable assay of uridylate sequences longer than 10 is described. The procedure is based on the hybridization of [3H]poly(A) with poly(U) or oligo(U) sequences in high ionic conditions and a subsequent degradation of single stranded polynucleotides with purified Taka-diastase. A 1:2 complex between poly(A) and poly(U) is formed on which on poly(U) strand is digested by Taka-diastase. The procedure is especially suitable for the detection and quantitation of Un (n greater than 10) in RNA preparation. 相似文献
989.
The molecular weight of Artemia ribosomes, as determined from their refractive-index increment and light-scattering intensity 下载免费PDF全文
Cytoplasmic ribosomes were isolated from the cryptobiotic embryos of the brine shrimp Artemia salina. Measurements of their refractive-index increments and light-scattering intensities give a value for their molecular weight of (3.4±0.2)×106. 相似文献
990.
O-(4-Diazo-3,5-di[125I]iodobenzoyl)sucrose, a novel radioactive label for determining organ sites of catabolism of plasma proteins. 总被引:7,自引:6,他引:1 下载免费PDF全文
A method is described for radiolabelling proteins with O-(4-diazo-3,5-di[125I]iodobenzoyl)sucrose (DD125IBS). When proteins so labelled were degraded within lysosomes, the radioactive fragments were largely retained within the organelle. High specific radioactivities were obtained without changing the properties of the protein. The validity of the method was demonstrated in vivo in rats using the short-lived protein lactate dehydrogenase, isoenzyme M4, and the long-lived protein bovine serum albumin. Derivatization with DD125IBS did not alter the clearance of either protein. Uptake of DD125IBS-labelled lactate dehydrogenase, isoenzyme M4, by liver and spleen of rats was determined. Radioactivity in these tissues increased up to about 2 h after injection (at this time the protein has been almost completely cleared from the blood) and subsequently declined with a half-life of approx. 20 h. After differential fractionation of liver, radioactivity was largely found in the mitochondrial and lysosomal fraction. The results of these studies establish that DD125IBS covalently coupled to plasma proteins should be a useful radioactive tracer for identifying the tissue and cellular sites of catabolism of relatively long-lived circulating proteins. 相似文献