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921.
Jeffrey B. Pardes Hajime Takagi Theresa A. Martin M. Sofia Ochoa Vincent Falanga 《Journal of cellular physiology》1995,162(1):9-14
We have investigated human neonatal fibroblast synthetic activity in response to fibrin substrates and components of fibrin formation and degradation. Greater than threefold downregulation of procollagen mRNA levels was seen 24 hours after fibroblasts were grown on fibrin gels as compared to tissue culture plastic. This downregulation occurred in both reptilase-generated fibrin (retention of fibrinopeptide B) and thrombin-generated fibrin (loss of both fibrinopeptide A and B). However, fibroblasts grown on fibrin retained their capacity to respond to the stimulatory action of transforming growth factor (TGF)-beta 1. Fibroblasts seeded on reptilase-generated fibrin displayed an abnormal morphology manifested by dendritic appearance and cell rounding, while fibroblast attachment was enhanced by 30% on thrombin-generated fibrin substrate (P < 0.02). Fibrinopeptides A and B, which are generated during fibrin formation, increased and decreased procollagen mRNA levels, respectively. Tissue plasminogen activator (t-PA) increased procollagen mRNA and TGF-beta 1 levels as early as 6 hours after cells were grown on tissue culture plastic, but this stimulation did not occur in cells cultured on a fibrin substrate. We conclude that alpha 1(I) procollagen mRNA levels in cultures of human dermal fibroblasts are consistently down-regulated by a fibrin substrate and are directly and profoundly influenced by complex interactions between components involved in the formation and removal of fibrin. © 1995 Wiley-Liss, Inc. 相似文献
922.
Nucleotide sequence and replication properties of the Bacillus borstelensis cryptic plasmid pHT926.
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S Ebisu Y Murahashi H Takagi K Kadowaki K Yamaguchi H Yamagata S Udaka 《Applied microbiology》1995,61(8):3154-3157
The nucleotide sequence of pHT926, a cryptic plasmid found in Bacillus borstelensis HP926, was determined. pHT926 replicates by a rolling-circle mechanism and belongs to the pC194 plasmid family. The copy number of pHT926 was fourfold higher than that of pUB110 and very stably maintained in Bacillus choshinensis. 相似文献
923.
Inducible expression of a gene encoding an L41 ribosomal protein responsible for the cycloheximide-resistant phenotype in the yeast Candida maltosa.
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In a previous paper (S. Kawai, S. Murao, M. Mochizuki, I. Shibuya, K. Yano, and M. Takagi, J. Bacteriol. 174:254-262, 1992), we showed that in each genome of several yeast species, there is one of two types of L41 gene, one for an L41 (Q-type) protein which confers cycloheximide (CYH) resistance or one for an L41 (P-type) protein which does not. These genes have been suggested to be responsible for the CYH response used in taxonomy. For example, Saccharomyces cerevisiae, which is CYH sensitive, has a P-type L41 gene, while Kluyveromyces fragilis and Candida maltosa, which are CYH resistant, have Q-type L41 genes. However, in contrast to K. fragilis, which is constitutively resistant to CYH, C. maltosa is inducibly resistant to CYH. Here, we show that C. maltosa has both types of the L41 gene in its genome and that expression of the Q-type L41 gene is induced by CYH while the P-type L41 gene is constitutively expressed. 相似文献
924.
Ikuei Nukaya Kuniaki Takagi Takefumi Kawabe Yasunobu Suketa 《Microbiology and immunology》1995,39(9):709-714
We examined the effect of nitric oxide (NO) on cytokine production in T helper (Th) cell subsets, using murine splenic CD4+ T cells and two types of Th clones. Interferon-gamma-treated murine peritoneal exudate cells (IFN-PEC) suppressed DNA synthesis to 60% of the control level in CD4+ T cells stimulated with the anti-CD3 monoclonal antibody. The production of IL-2 and IL-4 in the CD4+ T cells decreased to 63.2% and 9.2%, respectively, of the control value by co-culture with IFN-PEC. The addition of NG-monomethyl-L -arginine (L-NMMA) partially recovered the suppression of DNA synthesis. In the presence of indomethacin, the suppression of DNA synthesis was partially inhibited and the reduction in the cytokine production caused by IFN-PEC was partially recovered. The simultaneous addition of NG-monomethyl-L -arginine (L-NMMA) and indomethacin completely inhibited not only the suppression of DNA synthesis but also the reduction in the cytokine production caused by IFN-PEC. Moreover, DNA synthesis in the Th2 clone was suppressed to a greater extent than that in the Th1 clone by co-culture with IFN-PEC. This suppression in the Th1 clone was inhibited by the addition of L-NMMA, whereas the DNA synthesis in the Th2 clone was not recovered by L-NMMA. In addition, sodium nitroprusside (SNP) suppressed IL-4 production in the Th2 clone but had no effect on IL-2 production in the Th1 clone. In the experiment of the co-culture with IFN-PEC, the inhibitory-effect of NO on T cell activation was not clarified by the influence of prostaglandins. However, in conclusion, cytokine production in Th2 cells may be more susceptible to NO than that in Th1 cells. 相似文献
925.
926.
Masaki Fujita Tatsuya Morooka Shuji Fujimoto Tetsuhiro Moriya Kazunobu Amako 《Archives of microbiology》1995,164(6):444-447
Chromosomal DNA of 27 strains of Campylobacter fetus was analyzed by Southern blotting with a probe of the conserved region of sapA. The probe hybridized with 23 strains that produced type A lipopolysaccharide. These strains had more than six sapA homologs. In Southern blots of SalI-digested chromosomal DNA separated by pulsed-field gel electrophoresis, one fragment from 19 strains and two fragments from
4 strains hybridized. These data indicate that multiple sapA homologs are localized to a limited region on the chromosomal DNA of C. fetus and thus suggest the possibility of developing a typing system using this method.
Received: 28 June 1995 / Accepted: 19 September 1995 相似文献
927.
Nakashima Jin; Awano Tatsuya; Takabe Keiji; Fujita Minoru; Saiki Hiroshi 《Plant & cell physiology》1997,38(2):113-123
Secondary wall thickening is the most characteristic morphologicalfeature of the differentiation of tracheary elements. Isolatedmesophyll cells of Zinnia elegans L. cv. Canary Bird in differentiationmedium are converted to tracheary elements, which develop lignifiedsecondary wall thickenings. Using this system, we investigatedthe distribution of two enzymes, phenylalanine ammonia-Iyase(PAL) (EC 4.3.1.5
[EC]
) and cinnamyl alcohol dehydrogenase (CAD)(EC 1.1.1.195
[EC]
), by both biochemical and immunological methods.Both PAL and CAD appear to be key enzymes in the biosynthesisof lignin precursors, and they have been shown to be associatedwith the differentiation of tracheary elements. Cultured cellswere collected after various times in culture. The culture mediumwas separated from cells by centrifugation and designated fraction(1), the extracellular fraction. The collected cells were homogenizedand separated into four fractions: (2) cytosol; (3) microsomes;(4) cell walls (loosely bound material); and (5) cell walls(tightly bound material). PAL activity was detected in eachfraction. The extracellular fraction consistently had the greatestPAL activity. Moreover, PAL activity in the cytosolic fractionincreased rapidly prior to lignification, as it did in boththe microsomal and the cell wall (tightly bound) fractions duringlignification. Antisera against PAL and against CAD detectedthe proteins with molecular masses that corresponded to thoseof PAL and CAD in Zinnia. Immuno-electron microscopy revealedthat, in differentiating tracheary elements, PAL was dispersedin the cytoplasmic matrix and was located on Golgi-derived vesiclesand on the secondary wall thickenings. "Cell-free" immuno-lightmicroscopy supported the putative distribution of PAL on lignifyingsecondary walls. The pattern of distribution of CAD was similarto that of PAL. Thus, both PAL and CAD seemed to be localizedin secondary wall thickenings. From the results of both biochemicalassays and immunocytochemical staining, it appeared that atleast two types of PAL and CAD are present in differentiatingcells. One type of each enzyme is distributed in the cytosol,while the other is secreted from the Golgi apparatus and transportedby Golgi-derived vesicles to the secondary wall thickenings. (Received April 19, 1996; Accepted November 18, 1996) 相似文献
928.
Takeaki Nagamine Hitoshi Takagi Yoshiaki Hashimoto Hisashi Takayama Ryuya Shimoda Naruo Nomura Keiji Suzuki Masatomo Mori Katsuyuki Nakajima 《Biological trace element research》1997,58(1-2):65-76
We have studied zinc deficiency in hepatitis C patients (complete responder [C,R] 22, nonresponder [NR] 25) with relation to the therapeutic effect of interferon-α (IFN-α). Circadian variations in serum zinc levels were high in the morning (basal level) and then gradually decreased during the day in both chronic hepatitis C patients and healthy controls. Basal zinc levels in serum were significantly lower in chronic hepatitis C patients (73±3 μg/dL,n=12) than in controls (93±5 μg/dL). An injection of 10 MU of IFN-α to hepatitis C patients augmented the serum zinc reductions, up to 40% in 8 h. Serum cortisol levels were significantly elevated 8 h (25.6±2.3 μg/dL) after IFN-α dose. Forty-seven chronic hepatitis C patients were treated with IFN-α for 24 wk, and serum zinc and copper levels were determined 12 and 24 wk during and after the completion of IFN-α therapy. Serum zinc levels and zinc/copper ratio were higher in CRs than in NRs to IFN therapy at each time-point. Hepatic metallothionein staining became prominent after IFN therapy in most of CRs, whereas it diminished NRs. These data suggest that nutritional status of zinc influences the effect of IFN on hepatitis C patients. 相似文献
929.
Since some amino acids, polyols and sugars in cells are thought to be osmoprotectants, we expected that several amino acids
might also contribute to enhancing freeze tolerance in yeast cells. In fact, proline and charged amino acids such as glutamate,
arginine and lysine showed a marked cryoprotective activity nearly equivalent to that of glycerol or trehalose, both known
as major cryoprotectants for Saccharomyces cerevisiae. To investigate the cryoprotective effect of proline on the freezing stress of yeast, we isolated proline-analogue-resistant
mutants derived from a proline-non-utilizing strain of S. cerevisiae. When cultured in liquid minimal medium, many mutants showed a prominent increase, two- to approximately tenfold, in cell
viability compared to the parent after freezing in the medium at −20 °C for 1 week. Some of the freeze-tolerant mutants were
found to accumulate a higher amount of proline, as well as of glutamate and arginine which are involved in proline metabolism.
It was also observed that proline-non-utilizer and the freeze-tolerant mutants were able to grow against osmotic stress. These
results suggest that the increased flux in the meta-bolic pathway of specific amino acids such as proline is effective for
breeding novel freeze-tolerant yeasts.
Received: 6 November 1996 / Accepted: 7 December 1996 相似文献
930.
A fungal chitinase gene fromRhizopus oligosporus confers antifungal activity to transgenic tobacco 总被引:1,自引:0,他引:1
We have studied whether a chitinase involved in cell autolysis of a filamentous fungus,Rhizopus oligosporus, can operate as an antifungal defense system in tobacco. Thechi1 gene was introduced into tobacco by theAgrobacterium tumefaciens leaf disc system. Among 22 transgenic tobacco plants, 2 were selected and their individual homozygous progeny, Tch1-1 and Tch2-1, were studied. Chitinase activity in the extracts of young leaves from Tch1-1 or Tch2-1, in which thechi1 gene product was detected by Western blot analysis, was three- to four-fold higher than that from the control plants. A fungal infection assay on the leaves infected with the discomycete pathogensSclerotinia sclerotiorum andBotrytis cinerea revealed that the symptoms observed with these two were remarkably suppressed as compared with the control leaves.Abbreviations
CaMV
Cauliflower mosaic virus
-
Km
r
kanamycin resistant
-
Km
s
kanamycin sensitive
-
MS
Murashige and Skoog
-
PCR
polymerase chain reaction
-
PDA
potato dextrose agar
-
PR
pathogenesis-related 相似文献