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51.
The reaction to C-banding was investigated throughout the mitotic cycle ofCrepis capillaris (2n=6): (1) 18–22 C-bodies or C-bands were found during mid telophase and interphase to prophase and metaphase, and also
12–14 at late anaphase to early telophase in the mitotic cycle. Fewer C-bands in late anaphase to early telophase were due
to the absence of minute bands; (2) large and medium sized C-bands were strongly stained by Giemsa, while small and minute
bands stained palely. It is suggested that inCrepis capillaris the difference of color in C-banded segments following Giemsa staining is referable to the amount of constitutive heterochromatin
rather than to the difference in the condensation and decondensation; (3) the size of C-bodies changed during telophase to
interphase and prophase. It is inferred that the extent of C-bodies is regulated by both the length of DNA sequences of constitutive
heterochromatin and the amount of proteins combined with C-banded DNA. It was shown that the reaction to C-banding is neither
due to the differential condensation of chromatin nor to a higher concentration of DNA in the C-banded regions, in the C-banding
mechanism as has been suggested so far at least. 相似文献
52.
Nucleotide sequence of the chromosomal gene coding for the aminoglycoside 6-adenylyltransferase from Bacillus subtilis Marburg 168 总被引:2,自引:0,他引:2
Gene aadK of Bacillus subtilis is 855 bp long and codes for aminoglycoside 6-adenylyltransferase. 相似文献
53.
54.
The cell cycle block and lysis of an activated T cell hybridoma are distinct processes with different Ca2+ requirements and sensitivity to cyclosporine A 总被引:13,自引:0,他引:13
M Mer?ep P D Noguchi J D Ashwell 《Journal of immunology (Baltimore, Md. : 1950)》1989,142(11):4085-4092
Stimulation of transformed T cells leads to both lymphokine secretion and inhibition of spontaneous growth. Studies performed with an Ag-specific T cell hybridoma demonstrated that growth inhibition is an early (within 1 h) manifestation of activation. Experiment in which extracellular Ca2+ was chelated or in which cyclosporine A was included indicated that activation-associated growth inhibition is a two-step process. The first phase is the establishment of a G1/S cell cycle block; it does not require extracellular Ca2+ and is not prevented by the addition of cyclosporine A. The second phase is cell lysis. It can be detected 4 to 6 h after activation, requires the presence of extracellular Ca2+, and is prevented when stimulation occurs in the presence of cyclosporine A. The observation that both Ca2+ depletion and cyclosporine A prevented IL-2 secretion at all time points indicates that the pathways leading to lymphokine secretion and the G1/S block diverge early in the course of the cellular response, and establish the cell cycle block as a distinct activation event with unique characteristics. 相似文献
55.
The sre gene (ORF469) encodes a site-specific recombinase responsible for integration of the R4 phage genome. 总被引:3,自引:0,他引:3 下载免费PDF全文
M Matsuura T Noguchi D Yamaguchi T Aida M Asayama H Takahashi M Shirai 《Journal of bacteriology》1996,178(11):3374-3376
The sre gene (ORF469) of the R4 phage encodes a protein similar to the resolvase-DNA invertase family proteins. Insertional gene disruption of sre prevented a lysogen from entering the lytic cycle, implying that Sre protein is a site-specific recombinase needed for excision of the R4 prophage genome (M. Matsuura, T. Noguchi, T. Aida, M. Asayama, H. Takahashi, and M. Shirai, J. Gen. Appl. Microbiol. 41:53-61, 1995). To determine whether this sre gene is also necessary for the integration reaction, we studied its function by integration plasmid analysis. When deletions, frameshifts, and site-directed mutations that caused an amino acid substitution of Ser-17 for Ala were introduced into the sre structural gene, transformation efficiency of Streptomyces parvulus 2297 with these plasmid DNAs was severely reduced. However, an adenine insertion just before the possible initiation codon of the sre gene did not significantly decrease the efficiency. These data suggest that the Sre protein is a site-specific recombinase responsible for integration of the R4 phage genome. 相似文献
56.
Yuichi Murayama Ryozaburo Mukai Tetsutaro Sata Satoko Matsunaga Atsuo Noguchi Yasuhiro Yoshikawa 《Microbiology and immunology》1996,40(6):467-471
In contrast to the case of peripheral T cells, the surface expression of CD20 antigen and the expression of CD20 mRNA in monkey lymph node (LN) T cells underwent a noticeable increase when they were cultured with mitogen and interleukin-2 (IL-2). To confirm in vivo regulation of CD20 expression during the activation of LN T cells, we examined LNs derived from monkeys experimentally inoculated with simian immunodeficiency virus (SIV). Significant expression of CD20 antigen was detected in the T cells of the LNs at the stage of lymphadenopathy. These findings suggest that lymphocyte activation in the LNs induced expression of the CD20 molecule in some T cells. 相似文献
57.
Dis3, implicated in mitotic control, binds directly to Ran and enhances the GEF activity of RCC1. 总被引:9,自引:0,他引:9 下载免费PDF全文
E Noguchi N Hayashi Y Azuma T Seki M Nakamura N Nakashima M Yanagida X He U Mueller S Sazer T Nishimoto 《The EMBO journal》1996,15(20):5595-5605
Using the two-hybrid method, we isolated a Saccharomyces cerevisiae cDNA encoding a protein homologous to Schizosaccharomyces pombe protein Dis3sp, using as bait, human GTPase Ran. The DIS3 gene is essential for viability and complements S.pombe mutant dis3-54 which is defective in mitosis. Although Dis3sc has no homology to RanBP1, it bound directly to Ran and the S.cerevisiae Ran homologue Cnr1, but not to the S.cerevisiae RCC1 homologue Srm1. Upon binding to Ran with a 1:1 molar ratio, Dis3sc enhanced a nucleotide-releasing activity of RCC1 on Ran. In the presence of Dis3sc, the K(m) of RCC1 on Ran decreased by half, while the kcat was unchanged. In vivo, Dis3sp was present as oligomers of M(r) 670-200 kDa as previously reported, and the 200 kDa oligomer of Dis3sp was found to include Spi1 and Pim1, the S.pombe homologues of Ran and RCC1, respectively. Although the biological function of the heterotrimeric oligomer consisting of Dis3, Spi1 and Pim1 is unknown, our results indicate that Dis3 is a component of the RCC1-Ran pathway. 相似文献
58.
Neutral red (NR) in the culture medium entered the vacuolesof a green alga, Micrasterias pinnatifida, at a higher rateat pH 8 than at pH 5. NR remained soluble in vacuoles of cellscultured at pH 5, while it precipitated and formed granulesin cells cultured at pH 8. The vacuoles of cells cultured atpH 8 contained fibrils, but those of cells cultured at pH 5did not. The amount of NR that entered the cells was markedlyreduced by the addition to the medium of nigericin at 10-5M,monensin at 10-5M, bafilo-mycin A1 at 10-5M, or ammonium chlorideat 50 mM. The formation of NR granules in vacuoles were stronglyinhibited and the disorganization of NR granules were acceleratedby the addition of nigericin at 10-5M, or bafilomycin A1 at10-5M to the culture medium. The possibility is discussed thatNR which enters vacuoles might become positively charged (NRH+)by protons brought into vacuoles by proton pumps and that NRH+might combine with some negatively charged macromolecules toform aggregates or granules. (Received April 18, 1996; Accepted May 27, 1996) 相似文献
59.
To clarify the way in which the light available for growth affectsrespiration in leaves of sun and shade plants, we examined therespiratory properties of mature leaves of Spinacia oleraceaL., a sun species, and of Alocasia macrorrhiza (L.) G. Don.,a shade species, that had been grown at various irradiances.In leaves of S. oleracea, the respiratory rates, on a dry massbasis, decreased with time during the night, and the higherwas the growth irradiance during the day, the higher was therespiratory rate. The marked decreases in the respiratory rateduring the night were accompanied by decreases in the concentrationof carbohydrates in the leaves. By contrast, the respiratoryrates of leaves of A. macrorrhiza were virtually constant throughoutthe night and the absolute rates were lower than those of S.oleracea even though the absolute value of the concentrationof carbohydrates and its decrease at night resembled to thosein S. oleracea. The maximum activities of respiratory enzymeswere also similar to those in S. oleracea. However, the leavesof A. macrorrhiza contained less soluble protein than thoseof S. oleracea. These results suggest that, in S. oleracea,the concentration of carbohydrates might determine the respiratoryrate while such is not the case in A. macrorrhiza. The lowerrespiratory rates in A. macrorrhiza might be due to a lowerdemand for ATP. (Received November 29, 1995; Accepted February 15, 1996) 相似文献
60.
Elisabeth Steichen-Gersdorf Holly H. Gallion Deborah Ford Catherine Girodet Douglas F. Easton Richard A. DiCioccio Gareth Evans Margaret A. Ponder Carole Pye Sylvie Mazoyer Tetsuro Noguchi Fabienne Karengueven Hagay Sobol A. Hardouin Yves-Jean Bignon M. Steven Piver Simon A. Smith Bruce A. J. Ponder 《American journal of human genetics》1994,55(5):870-875
In a study of nine families with “site-specific” ovarian cancer (criterion: three or more cases of epithelial ovarian cancer and no cases of breast cancer diagnosed at age <50 years) we have obtained evidence of linkage to the breast-ovarian cancer susceptibility gene, BRCA1 on 17q12-21. If the risk of cancer in these families is assumed to be restricted to the ovary, the best estimate of the proportion of families linked to BRCA1 is .78 (95% confidence interval .32–1.0). If predisposition to both breast and ovarian cancer is assumed, the proportion linked is 1.0 (95% confidence interval .46–1.0). The linkage of familial site-specific ovarian cancer to BRCA1 indicates the possibility of predictive testing in such families; however, this is only appropriate in families where the evidence for linkage to BRCA1 is conclusive. 相似文献