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81.
J Aramburu M A Balboa A Ramírez A Silva A Acevedo F Sánchez-Madrid M O De Landázuri M López-Botet 《Journal of immunology (Baltimore, Md. : 1950)》1990,144(8):3238-3247
In the present study we describe a novel functional cell surface molecule, designated as Kp43, which is expressed among leukocytes by NK cells, TCR-gamma/delta + T lymphocytes, and some CD8+ CD56+TCR-alpha/beta + T cell clones. The Kp43 Ag is a 70-kDa disulfide-linked dimer, which migrates in SDS-PAGE under reducing conditions as a single 43-kDa band. Two-color immunofluorescence staining of fresh PBL revealed that only a fraction of CD16+, and of TCR-gamma/delta + T lymphocytes expressed the Ag. The analysis of TCR-alpha/beta + T cell clones showed that a small proportion (2 out of 20) weakly expressed Kp43 together with the CD8 and CD56 molecules. By immunoperoxidase staining of different tissues the anti-Kp43, reactivity was detected exclusively in lymphoid organs, where a minority of scattered cells was stained, and in some liver sinusoidal cells. Essentially all NK cells acquired Kp43 when stimulated with a B lymphoblastoid cell line. By contrast, the pattern of distribution of Kp43 remained stable upon in vitro culture of T-gamma/delta lymphocytes, thus delineating two subsets according to its expression. In lymphokine-activated killer populations, obtained by culturing either PBL or NK cells with high concentration of IL-2, most CD16+ and CD56+ cells became Kp43+. The Kp43-specific mAb inhibited the IL-2-dependent proliferative response of cultured NK and TCR-gamma/delta + T cells without affecting their non-MHC-restricted cytotoxicity. The partial inhibitory effect, which was mediated as well by pepsin digested F(ab')2 fragments, was lost upon reduction to Fab. The anti-Kp43 mAb did not interfere with the specific binding of IL-2 to its surface receptors. Altogether the data point out that the Kp43 dimer is involved in the regulation of the IL-2-dependent proliferative response of NK cells and a subset of TCR-gamma/delta + T lymphocytes. 相似文献
82.
A study was undertaken to compare the susceptibility of laboratory-reared female Lutzomyia longipalpis to infection by different species or strains of New World Leishmania. The sand flies proved to be highly susceptible to infection by a strain of Le. guyanensis, with flagellates developing in all (18/18) of the specimens examined. A lower infection rate of 37% (10/27) was recorded in flies exposed to infection by a strain of Le. amazonensis. Flagellates developed in 13% (6/46) of the sand flies that blood fed on dogs in the early stage of experimental infection with an old laboratory strain of Le. chagasi. In contrast, promastigotes did not develop in sand flies that blood fed on dogs with naturally acquired Le. chagasi. The naturally infected dogs were in an advanced stage of disease. Flagellates developed in 9% (3/32) of the sand flies that blood fed on lesions of hamsters infected with a strain of Le. braziliensis and in 9% (3/34) of those that fed on hamsters with lesions due to a parasite of the mexicana complex (strain MHOM/BR/73/BH121). Sand flies did not develop flagellate infections after blood feeding on hamsters bearing lesions induced by strain MHOM/BR/71/BR49. Factors influencing the susceptibility of Lu. longipalpis to infection by New World species of Leishmania are discussed. 相似文献
83.
Nef genes of SIV 总被引:4,自引:0,他引:4
H W Kestler K Mori D P Silva T Kodama N W King M D Daniel R C Desrosiers 《Journal of medical primatology》1990,19(3-4):421-429
Molecular clones of SIVmac were constructed that differed only in sequences within the nef gene. DEAE-transfection of viral DNA containing an open from of nef yielded virus that replicated with similar kinetics and to a similar extent in macaque peripheral blood lymphocyte (PBL) cultures as virus with a deletion or stop codon within nef. Rhesus monkeys that received each kind of molecularly cloned virus became infected. Our results additionally suggest that mutant forms of virus are selected in vitro while open, functional forms are selected in vivo. In animals infected with virus containing a stop codon within nef, reversion of the stop codon to a coding codon was demonstrated in five of five clones analyzed. These results indicate that nef is playing some role crucial to the virus life cycle in vivo. 相似文献
84.
Silastic devices impregnated with oestradiol and blank devices were placed around both oviducts and around skeletal muscle bundles in the forelegs to attain local and systematic delivery, respectively. Another group of mice received an oestradiol-impregnated device around one oviduct and a blank device in the contralateral oviduct. Implantation of blank devices around the oviducts and in the forelegs did not alter ovum transport. Devices impregnated with oestradiol placed around both oviducts produced a dose-dependent delay of ovum transport, which was more pronounced than the effect of devices located in the forelegs. Oviducts receiving an oestradiol-loaded device had a larger retention of ova than did the contralateral oviducts receiving a blank device. These results demonstrate a direct action of oestradiol upon the oviduct to delay ovum transport in the mouse. 相似文献
85.
86.
Concentration dependence of the subunit association of oligomers and viruses and the modification of the latter by urea binding. 总被引:2,自引:1,他引:1
A theoretical model is presented that accounts for the facilitation of the pressure dissociation of R17 phage, and for the partial restoration of the concentration dependence of the dissociation, by the presence of subdenaturing concentrations of urea. As an indifferent osmolyte urea should promote the stability of the protein aggregates under pressure, and the decrease in pressure stability with urea concentration demonstrates that such indirect solvent effects are not significant for this case, and that the progressive destabilization is the result of direct protein-urea interactions. By acting as a "homogenizer" of the properties of the phage particles, urea addition converts the pressure-induced deterministic dissociation of the phage into a limited stochastic equilibrium. The model establishes the origin of the uniform progression from the stochastic equilibrium of dimers, to the temperature-dependent and partially concentration-dependent association of tetramers, to the fully deterministic equilibrium observed in many multimers and in the virus capsids. 相似文献
87.
Macrothrix mexicanus sp. nov. is described from central México, a transition zone between the nearctic and neotropics. All localities where it was found are over 1800 meters above sea level. It shows many resemblances with M. laticornis, M. camjatae and M. rosea but is characterized by a persistent dorsal tooth on the valve keel, a spinous papilla on the basipodite of the antenna, the second thoracic limb with a long conical sensillum between scraper 1 and the gnathobase, the endopod of trunk limb IV having two setae; the postabdomen with the dorsal margin bilobed, and the distal segment of the seta natatoria which is unusually long.Abbreviations used on figures EN
Endopodite
- EP
Epipodite
- EX
Exopodite
- IDL
Inner distal lobe
- ODL
Outer distal lobe
- GT
Gnatobase
- E1
Endite 1
- E2
Endite 2
- E3
Endite 3 相似文献
88.
R. C. Minussi J. L. C. Coelho M. C. Baracat-Pereira D. O. Silva 《Biotechnology letters》1996,18(11):1283-1286
Summary Mycelial growth and production of extracellular pectin lyase by Penicillium griseoroseum at different concentrations of inducers were investigated. The fungus was cultured in mineral medium using sucrose as a carbon source and caffeine, yeast extract, tea extract or pectin as inducers. Caffeine, yeast extract and tea extract in the presence of sucrose, and tea extract alone were capable of inducing pectin lyase in P. griseoroseum, even at low concentrations. 相似文献
89.
Summary Two plasmids isolated from Lactobacillus helveticus strain ILC 54 were analysed by restriction digestion. A restriction map of the 14.3 and 5.6 kb plasmids is presented. Plasmid-curing studies suggest that these plasmids are involved in lactose metabolism and peptidase activity. 相似文献
90.
Markers for selection of the rice Xa21 disease resistance gene 总被引:8,自引:0,他引:8
C. E. Williams B. Wang T. E. Holsten J. Scambray F. de Assis Goes da Silva P. C. Ronald 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(7):1119-1122
Six molecular markers were mapped to a 7.4-cM region of rice chromosome 11 containing the Xa21 gene, which confers resistance to the pathogen Xanthomonas oryzae pv oryzae. Three markers, RG103, 248 and 818, co-segregated with Xa21 in a population of 1141 plants. Multiple copies of all marker loci were present within the region that was introgressed from Oryza longistaminata into O. sativa. The marker loci were cloned and primers were designed that defined sequence-tagged sites. Physical mapping of the three tightly linked central markers revealed that RG103, the marker that hybridizes to the Xa21 gene, resides on a separate DNA fragment from the other two markers.Disclaimer: Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. 相似文献