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121.
Exclusive and Persistent Use of the Entry Coreceptor CXCR4 by Human Immunodeficiency Virus Type 1 from a Subject Homozygous for CCR5 Δ32 下载免费PDF全文
Nelson L. Michael Julie A. E. Nelson Vineet N. KewalRamani George Chang Stephen J. OBrien John R. Mascola Barbara Volsky Mark Louder Gilbert C. White II Dan R. Littman Ronald Swanstrom Thomas R. OBrien 《Journal of virology》1998,72(7):6040-6047
Individuals who are homozygous for the 32-bp deletion in the gene coding for the chemokine receptor and major human immunodeficiency virus type 1 (HIV-1) coreceptor CCR5 (CCR5 −/−) lack functional cell surface CCR5 molecules and are relatively resistant to HIV-1 infection. HIV-1 infection in CCR5 −/− individuals, although rare, has been increasingly documented. We now report that the viral quasispecies from one such individual throughout disease is homogenous, T cell line tropic, and phenotypically syncytium inducing (SI); exclusively uses CXCR4; and replicates well in CCR5 −/− primary T cells. The recently discovered coreceptors BOB and Bonzo are not used. Although early and persistent SI variants have been described in longitudinal studies, this is the first demonstration of exclusive and persistent CXCR4 usage. With the caveat that the earliest viruses available from this subject were from approximately 4 years following primary infection, these data suggest that HIV-1 infection can be mediated and persistently maintained by viruses which exclusively utilize CXCR4. The lack of evolution toward the available minor coreceptors in this subject underscores the dominant biological roles of the major coreceptors CCR5 and CXCR4. This and two similar subjects (R. Biti, R. Ffrench, J. Young, B. Bennetts, G. Stewart, and T. Liang, Nat. Med. 3:252–253, 1997; I. Theodoreu, L. Meyer, M. Magierowska, C. Katlama, and C. Rouzioux, Lancet 349:1219–1220, 1997) showed relatively rapid CD4+ T-cell declines despite average or low initial viral RNA load. Since viruses which use CXCR4 exclusively cannot infect macrophages, these data have implications for the relative infection of the T-cell compartment versus the macrophage compartment in vivo and for the development of CCR5-based therapeutics. 相似文献
122.
Summary Measuring the cough frequency of bluegills by means of a cannula inserted through the snout into the buccal cavity is a good monitoring technique for zinc (and probably other heavy metals) because the response is quick, is proportional to the toxicant concentration and occurs at sublethal concentrations. 相似文献
123.
Comparison of Two Liquid Blood Culture Media Containing Sodium Polyanetholesulfonate: Tryptic Soy and Columbia 下载免费PDF全文
In a comparison of tryptic soy broth and Columbia broth, two blood culture media containing sodium polyanetholesulfonate, there were 589 positive cultures (excluding presumed contaminants). The two media were equivalent in performance except for lower detection rates for Staphylococcus aureus (P < 0.01) and Pseudomonas aeruginosa (P = 0.05) and a higher detection rate for Bacillus (P < 0.01) in Columbia broth. No significant differences were noted in time intervals to detection of positivity. Routine subcultures on the 1st and 5th days of incubation provided the initial detection of 18.1% of the positive cultures. 相似文献
124.
Summary Rat red blood corpuscles were held stationary with respect to a continuously flowing solution in either a specially constructed centrifuge or in glass filters. The concentration of the solution was gradually decreased to cause the swelling and subsequent gradual osmotic hemolysis of the cells. The passage of the intracellular molecules —potassium, adenylate kinase, and hemoglobin—across the cell membranes and into the flowing solution was determined as a function of time. Ions and molecules begin passage across the membranes in the order of increasing molecular size. The initial flow of potassium is followed by the initial flows of hemoglobin and adenylate kinase. The flow of hemoglobin has been interpreted as the flows of hemoglobin monomers, dimers, and tetramers such that the time sequence is: potassium; hemoglobin monomer; adenylate kinase/hemoglobin dimer; and finally, hemoglobin tetramer. It is concluded that the stressed cell membrane has molecular sieving properties and that the exclusion limit (effective hole size) increases as a function of time during the initial stages of gradual osmotic hemolysis. The process of gradual osmotic hemolysis is discussed in terms of molecular sieving through stress-induced effective membrane holes. It is suggested that a portion of the membrane protein might form an elastic network which would account for the gradual increase in size and apparent homogeneity of the effective holes.This work was prepared under the auspices of the U.S. Atomic Energy Commission. 相似文献
125.
Evaluation of the Enterotube System for Identification of Members of the Family Enterobacteriaceae 总被引:8,自引:4,他引:4 下载免费PDF全文
William Jeffery Martin Pauline K. W. Yu John A. Washington II 《Applied microbiology》1971,22(1):96-99
The Enterotube system was evaluated, in parallel with conventional bacteriological procedures for the identification of members of the family Enterobacteriaceae, by using bacterial strains from a variety of clinical specimens and from stock cultures. Excellent agreement between the two test systems was obtained with the following reactions: hydrogen sulfide, indole, Simmons' citrate, glucose, and lactose. Agreement was not as good (<85%) with the urea, phenylalanine deaminase, and dulcitol reactions. The Enterotube lysine decarboxylase test was unsatisfactory. The Enterotube method will correctly identify strains of the family Enterobacteriaceae approximately 50% of the time; if identification only as Klebsiella-Enterobacter-Serratia group is needed, the method will be correct 85% of the time. On the basis of this evaluation, the Enterotube system appears to be both simple and rapid for the presumptive identification of these bacteria. Because of the limited usefulness of the lysine decarboxylase test, the results obtained by this test system are less reliable than those obtained by conventional methods. 相似文献
126.
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128.
During a 2.5-year study, streptococci were isolated from 280 patients (19% of those with bacteremia). Of this number, 54 had group D streptococci (45 were enterococci), 218 had α- or γ-hemolytic nongroup D streptococci, and 49 had β-hemolytic streptococci. 相似文献
129.
Of 43 older patients (aged 65 to 83 years) with arteriosclerosis obliterans treated by lumbar sympathectomy for one or both limbs, 19 had excellent result, 13 had fair result and four had poor result. One died postoperatively and six later. Results were better than prognosticated from response to sympathetic block. Thirty-four patients considered the operation worth while and twelve, after unilateral sympathectomy, requested operation for the other limb also. Twenty-four after operation could walk farther without claudication. 相似文献
130.