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61.
D K Wilcox P A Whitaker-Dowling J S Youngner C C Widnell 《Molecular and cellular biology》1983,3(8):1533-1536
Treating mouse L cells with crude or purified mouse interferon inhibited fluid-phase pinocytosis. Inhibition was maximum at 24 h after treatment with 1,000 U of interferon per ml and was dose dependent and reversible with time. Pinocytosis was inhibited when human and chicken embryo cells were treated with homologous, but not heterologous, interferons. 相似文献
62.
63.
K J Dolan 《American journal of physical anthropology》1971,35(1):109-117
Cranial suture closure is examined in two species of South American monkeys, Saimiri sciureus and Saguinus nigricollis. Sequences in closure were sought as indicators of skeletal age. Some sutures seem to be more reliable determinants of skeletal age than others, and these sutures and their sequence of closure are different in the two species examined. The sphenooccipital synchondrosis and the palatal portion of the Interpremaxillary suture show regular fusion associated with age in both species. In Saimiri the maxillopremaxillary sutures are also reliable indicators of age, whereas they are not in Saguinus; however, in the latter the presphenoid-postsphenoid synchondrosis closes regularly whereas it does not in Saimiri. In Saimiri the predictable sequence is (1) maxillo-premaxillary, (2) transverse maxillo-premaxillary, (3) spheno-occipital, (4) interpremaxillary. In Saguinus it is (1) presphenoid-postsphenoid, (2) spheno-occipital, (3) interpremaxillary. It is possible that the sequences of suture closure and the variability in this process may indicate genetic and taxonomic relationships. 相似文献
64.
Cephalexin and Cephaloglycin Activity In Vitro and Absorption and Urinary Excretion of Single Oral Doses in Normal Young Adults 总被引:3,自引:1,他引:2 下载免费PDF全文
Peter Braun James R. Tillotson Clare Wilcox Maxwell Finland 《Applied microbiology》1968,16(11):1684-1694
A large number of recently isolated bacterial pathogens were tested for susceptibility to cephalexin and cephaloglycin by the replica inoculating method. Strains of group A hemolytic streptococci, viridans (alpha and gamma) streptococci, pneumococci, gonococci, meningococci, and penicillin G-sensitive Staphylococcus aureus were all moderately to highly susceptible to both of these cephalosporin analogues, nearly all of the strains being two to eight (median four) times more susceptible to cephaloglycin than to cephalexin. The penicillin G-resistant, penicillinase-producing strains of S. aureus varied in their susceptibility; many were moderately resistant to both analogues, particularly to cephalexin. Strains of enterococci, Haemophilus influenzae, and most of the common gram-negative bacilli were moderately to highly resistant. Reducing the size of the inoculum had variable effects on inhibition by these drugs, depending on the species or strain. The activity of cephalexin was very little affected by pH of the medium within the clinical range or by incubation at 37 C in broth for up to 24 hr. In contrast, cephaloglycin in broth deteriorated rapidly at 37 C, and its activity was markedly reduced in alkaline medium. Both cephalexin and cephaloglycin were rapidly absorbed and excreted into the urine after single oral doses of 500 mg. Much higher levels were achieved and sustained with the former. Absorption of both analogues was delayed when taken with food, and the levels in the serum were significantly higher and better sustained when probenecid was also given. Very high concentrations of cephalexin were excreted into the urine during the first 4 hr, and the levels were still high in the 4- to 8-hr collection. The concentrations of cephaloglycin in the urine at these times were much lower. An average of 80 to 93% of the dose of cephalexin and 25 to 30% of the cephaloglycin were accounted for as active drug in the urine collected in 8 hr. Both analogues were well tolerated. 相似文献
65.
66.
Hugh Wilcox 《American journal of botany》1962,49(3):221-236
Wilcox , Hugh . (State U. Coll. of Forestry, Syracuse, New York.) Growth studies of the root of incense cedar, Libocedrus decurrens. I. The origin and development of primary tissues. Amer. Jour. Bot. 49(3): 221–236. Illus. 1962.—The anatomical features of active and dormant roots of incense-cedar seedlings are described and discussed in relation to various problems of differentiation and morphogenesis. Autoradiographs confirm the presence of a group of relatively inactive cells at the site of the apical initials. During periods of maximum growth activity, the presence of a quiescent center is accentuated by a peak in number of divisions in adjacent tissues. With diminution in growth activity, the peak occurs closer to the quiescent center and the size of the meristem appears to diminish. During dormancy, the configuration of the initial region seems to indicate the existence of apical initial cells which coincide with a minimal constructional center, as determined by studies of cell lineage. Roots whose apical cells retain their meristematic appearance are able to resume growth after a period of dormancy, whereas roots whose apical cells undergo vacuolation are likely to perish. Graphs are presented to show the functional relationships between growth rate and the varying distances from the apical meristem at which the tissues of the root differentiate and mature. Although early differentiation of precursory phloem could be discerned almost as soon as early vacuolation of metaxylem, its recognition was more dependent upon subjective judgment. The functional relationship between differentiation and growth rate was most pronounced in the maturation of protoxylem elements, the development of Casparian strips in the endodermis, the development of suberin lamellae in the endodermis, and by the development of phi layers in the inner cortex. 相似文献
67.
Identification of a site on herpes simplex virus type 1 glycoprotein D that is essential for infectivity. 下载免费PDF全文
Herpes simplex virus glycoprotein D (gD) plays an essential role during penetration of the virus into cells. There is evidence that it recognizes a specific receptor after initial attachment of virions to cell surface heparan sulfate and also that gD-1, gD-2, and gp50 (the pseudorabies virus gD homolog) bind to the same receptor. Although the antigenic structure of gD has been studied intensively, little is known about functional regions of the protein. Antigenic site I is a major target for neutralizing antibodies and has been partially mapped by using deletion mutants and neutralization-resistant viruses. Working on the assumption that such a site may overlap with a functional region of gD, we showed previously that combining two or more amino acid substitutions within site I prevents gD-1 from functioning and is therefore lethal. We have now used a complementation assay to measure the functional activity of a panel of deletion mutants and compared the results with an antigenic analysis. Several mutations cause gross changes in protein folding and destroy functional activity, whereas deletions at the N and C termini have little or no effect on either. In contrast, deletion of residues 234 to 244 has only localized effects on antigenicity but completely abolishes functional activity. This region, which is part of antigenic site Ib, is therefore essential for gD-1 function. The complementation assay was also used to show that a gD-negative type 1 virus can be rescued by gD-2 and by two gD-1-gD-2 hybrids but not by gp50, providing some support for the existence of a common receptor for herpes simplex virus types 1 and 2 but not pseudorabies virus. Alternatively, gp50 may lack a signal for incorporation into herpes simplex virions. 相似文献
68.
69.
Horoyuki Shimizu Deborah Wyatt Rebecca D. Knowles Corazon D. Bucana Eric J. Stanbridge Eugenie S. Kleinerman 《Cancer immunology, immunotherapy : CII》1989,28(3):185-192
Summary The characteristics of the binding of human monocytes to tumor cells were studied by a newly developed microassay. First, we determined the kinetics and optimal conditions of the binding. Monocytes recognized and bound to tumor cells very rapidly within 10–20 min of cellular interaction. Binding was also more efficient at 37°C suggesting that active metabolism of monocytes is required. Second, we determined that selective binding of monocytes to cells with tumorigenic phenotypes occurs. For this purpose, lymphocytic leukemia cell lines versus normal lymphocytes, and tumorigenic versus nontumorigenic hybrids from the same parental lines were compared as the targets of the binding assay. In both cases, neoplastic cells were selectively bound by monocytes. Although tumor cells were bound rapidly and selectively by monocytes, initial recognition and binding did not necessarily lead to subsequent tumor cell lysis. This is based on the observation that some tumorigenic parental and hybrid lines were avidly bound by monocytes yet not subsequently killed in a cytotoxicity assay.This work was supported in part by a grant from the National Institutes of Health CA42992 and a grant from the Kleberg foundation
Abbreviations used: [125I]IdUrd [125I]iododeoxyuridine; rIFN-, recombinant human interferon ; IL-1, interleukin 1; rTNF, recombinant human tumor necrosis factor 相似文献
70.
Effect of mutations in the cyclic AMP receptor protein-binding site on araBAD and araC expression. 总被引:4,自引:2,他引:2 下载免费PDF全文
Maximum expression of the adjacent but divergently transcribed araBAD operon and araC gene requires the presence of cyclic AMP (cAMP) and the cAMP receptor protein (CRP). DNase I protection studies have previously revealed a high-affinity CRP-binding site in the ara regulatory region. Deletion mutations introduced into this site resulted in reduced expression of araBAD and araC. However, other experiments have demonstrated that spacing changes in the ara regulatory region may have multiple effects due to disruption of a DNA loop. Thus, the deletions could have destroyed the CRP-binding site, the ability to form a loop, or both. In the present study, substitution mutations were introduced into the CRP site in order to avoid creating spacing changes. We found that a 3-base-pair substitution resulted in a 30% reduction in araBAD expression, whereas a 6-base-pair substitution resulted in an 80% reduction. Both of these substitution mutations reduced araC expression threefold. We conclude that CRP bound to this site regulates expression in both directions. We found that a spacing change in the CRP site does not alter araBAD expression any more than does a substitution mutation. 相似文献