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121.
Differentially regulated expression and function of CD22 in activated B-1 and B-2 lymphocytes 总被引:3,自引:0,他引:3
Lajaunias F Nitschke L Moll T Martinez-Soria E Semac I Chicheportiche Y Parkhouse RM Izui S 《Journal of immunology (Baltimore, Md. : 1950)》2002,168(12):6078-6083
CD22 is a B cell-restricted transmembrane protein that apparently controls signal transduction thresholds initiated through the B cell Ag receptor (BCR) in response to Ag. However, it is still poorly understood how the expression of CD22 is regulated in B cells after their activation. Here we show that the expression levels of CD22 in conventional B-2 cells are markedly down-regulated after cross-linking of BCR with anti-IgM mAb but are up-regulated after stimulation with LPS, anti-CD40 mAb, or IL-4. In contrast, treatment with anti-IgM mAb barely modulated the expression levels of CD22 in CD5(+) B-1 cells, consistent with a weak Ca(2+) response in anti-IgM-treated CD5(+) B-1 cells. Moreover, in CD22-deficient mice, anti-IgM treatment did not trigger enhanced Ca(2+) influx in CD5(+) B-1 cells, unlike CD22-deficient splenic B-2 cells, suggesting a relatively limited role of CD22 in BCR signaling in B-1 cells. In contrast, CD22 levels were markedly down-regulated on wild-type B-1 cells in response to LPS or unmethylated CpG-containing oligodeoxynucleotides. These data indicate that the expression and function of CD22 are differentially regulated in B-1 and conventional B-2 cells, which are apparently implicated in innate and adaptive immunity, respectively. 相似文献
122.
To understand the early steps of C(27) brassinosteroid biosynthesis, metabolic experiments were performed with Arabidopsis thaliana and Nicotiana tabacum seedlings, and with cultured Catharanthus roseus cells. [26, 28-2H(6)]Campestanol, [26-2H(3)]cholesterol, and [26-2H(3)]cholestanol were administered to each plant, and the resulting metabolites were analyzed by gas chromatography-mass spectrometry. In all the species examined, [2H(3)]cholestanol was identified as a metabolite of [2H(6)]campestanol, and [2H(3)]cholest-4-en-3-one and [2H(3)]cholestanol were identified as metabolites of [2H(3)]cholesterol. This study revealed that cholestanol (C(27) sterol) was biosynthesized from both cholesterol (C(27) sterol) and campestanol (C(28) sterol). It was also demonstrated that cholestanol was converted to 6-oxocholestanol, and campestanol was converted to 6-oxocampestanol. 相似文献
123.
A 33-kDa protein component of the oxygen-evolving complex in photosystem II is essential for photosynthesis, and it has been believed that mutants with deletion of this 33-kDa protein are not found in higher plants. We report here the first isolation of an Arabidopsis thaliana mutant with a defect in one of the genes for the 33-kDa proteins, psbO, and an intact gene (psbO2). This mutant showed considerable growth retardation, suggesting that there is a functional difference between psbO and psbO2. 相似文献
124.
Hidewaki Nakagawa Kumiko Koyama Yasuo Miyoshi Hiroshi Ando Shozo Baba Masahiro Watatani Masayuki Yasutomi Nariaki Matsuura Morito Monden Y. Nakamura 《Human genetics》1998,103(2):168-172
Peutz-Jeghers Syndrome (PJS) is an autosomal dominant hereditary disease characterized by hamartomatous polyposis involving
the entire bowel. Recently STK11, a gene bearing a mutation responsible for PJS, was isolated. We investigated the entire
coding region of STK11 in 15 unrelated PJS families by the PCR-SSCP (polymerase chain reaction-single strand conformation
polymorphism) method and PCR-direct sequence analysis, and found nine different, novel mutations among ten of those families.
One nonsense mutation and five different frameshift mutations (two families carried the same mutation), all of which would
cause truncation of the gene product, were found in seven families; mutations found in five families were clustered within
exon 6. Among these five mutations, three occurred at the mononucleotide-repeat region (CCCCCC) of codons 279–281, suggesting
that this region is likely to be a mutational hotspot of this gene. One of the remaining three families carried a 3-bp in-frame
deletion that would eliminate an asparagine residue within a kinase domain of the product; the other two carried intronic
mutations at or adjacent to the consensus dinucleotide sequences of splice-acceptor or -donor sites, which were likely to
lead to aberrant splicing.
Received: 9 March 1998 / Accepted: 1 May 1998 相似文献
125.
126.
Naoko Fukuta Shozo Fujioka Suguru Takatsuto Shigeo Yoshida Yoshimichi Fukuta Masayoshi Nakayama 《Physiologia plantarum》2004,121(3):506-512
A dwarf mutant of broad bean ( Vicia faba L.), the variety Rinrei, has been created by γ -ray irradiation. Rinrei is characterized by dark green leaves and by reduced plant length, internode and petiole length, shoot weight, and number of branches. Genetic analysis of hybrids between Rinrei and two wild-type lines indicated that these characteristics are controlled by a single recessive gene. The phenotype of Rinrei was restored to that of the wild type by application of brassinolide, but not by GA3 . Qualitative and quantitative analysis by gas chromatography–mass spectrometry indicated that 24-methylenecholesterol and isofucosterol accumulated in Rinrei to levels more than 30 times higher than in the wild type. In contrast, Rinrei had lower than wild-type levels of campesterol, sitosterol and brassinosteroids. Therefore, Rinrei is a brassinosteroid-deficient mutant defective in sterol C-24 reduction. The gene was tentatively designated as brassinosteroid deficient dwarf 1 , bdd1 , which seems to be a homologue of Arabidopsis dwf1 ( dim , cbb1 ) and pea lkb . 相似文献
127.
128.
Elizabeth A. Register Ruth Yokoyama Shozo Yokoyama 《Journal of molecular evolution》1994,39(3):268-273
Vertebrate opsins are divided into four major groups: RH1 (rhodopsins), RH2 (rhodopsinlike with various absorption sensitivities), SWS (short-wavelength sensitive), and LWS/MWS (long and middle-wavelength sensitive) groups. The green opsin genes (g101
Af
and g101
Af
) in a Mexican characin Astyanax fasciatus belong to the LWS/MWS group, whereas those in goldfish belong to the RH2 group (Yokoyama 1994, Mol Biol Evol 11:32–39). A newly isolated opsin gene (rh11
Af
) from A. fasciatus contains five exons and four introns, spanning 4.2 kilobases from start to stop codons. This gene is most closely related to the two green opsin genes of goldfish and belongs to the RH2 group. In the LWS/MWS group, gene duplication of the ancestral red and green opsin genes predates the speciation between A. fasciatus and goldfish, suggesting that goldfish also has an additional gene which is orthologous to g101
Af
and g103
Af
.Correspondence to: S. Yokoyama 相似文献
129.
The penetration of leucine-(U)-14C and glucose-(U)-14C throughthe bulb epidermal tissue of Allium cepa was examined in thepresence of indoleacetic acid (IAA). Not only the uptake ofleucine-14C and glucose-14C in epidermal tissue but also theirtranscellular penetration were accelerated by IAA treatment.N-Ethylmaleimide (NEM) inhibited their uptake and transcellularpenetration, and the inhibitory effect was relieved by additionalIAA. In the presence of IAA, leucine-14C and glucose-14C weremore penetrable by adaxial than abaxial application, but inthe absence almost no difference due to application side wasobserved. IAA appears to promote permeability of the epidermaltissue only to substances applied adaxially. N,N'-Dicyclohexylcarbodiimide(DCCD) showed a little inhibitory effect on the IAA-inducedpromotion of the uptake and penetration of leucine-14C appliedadaxially. Leucine-14C and glucose-14C penetrated more easilythrough killed than fresh tissue, with little difference betweenabaxial and adaxial applications.
1 Present address: Department of Biology, Faculty of Science,Kochi University, Kochi 780, Japan.
2 Present address: Department of Medical Zoology, Medical School,Mie University, Tsu 514, Japan. (Received October 13, 1977; ) 相似文献
130.
Selective inhibition of prostaglandin endoperoxide thromboxane isomerase by 1-carboxyalkylimidazoles
Tanihiro Yoshimoto Shozo Yamamoto Osamu Hayaishi 《Prostaglandins & other lipid mediators》1978,16(4):529-540
1-Carboxyalkylimidazoles inhibited the conversion of prostaglandin H2 to thromboxane B2 and 12L-hydroxy-5, 8, 10- heptadecatrienoic acid by a partially purified enzyme (prostaglandin endoperoxide thromboxane isomerase) from bovine platelet microsomes. The degree of the inhibition was dependent on the length of carboxyalkyl chain. 1-Carboxyheptylimidazole was the most potent inhibitor, and an almost complete inhibition was obtained at a concentration on the order of 1 μM. The inhibition, as examined with 1-carboxyheptylimidazole, was of noncompetitive type. These 1-carboxyalkylimidazoles did not affect the formation of prostaglandin H2 from arachidonic acid. Such a selective inhibition was also demonstrated by the reaction of bovine platelet microsomes with arachidonic acid in the presence of 1-carboxyheptylimidazole, resulting in the accumulation of prostaglandin H2 as an intermediate. Furthermore, a series of 1-alkylimidazoles with no carboxyl group also inhibited the isomerase at higher concentrations. However, the inhibition was not specific for the isomerase; namely, the prostaglandin H2 formation from arachidonic acid was also affected. 相似文献