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11.
ELECTRON MICROSCOPIC EXAMINATION OF THE SITES OF NUCLEAR RNA SYNTHESIS DURING AMPHIBIAN EMBRYOGENESIS 下载免费PDF全文
Shuichi Karasaki 《The Journal of cell biology》1965,26(3):937-958
The site of H3-uridine incorporation and the fate of labeled RNA during early embryo-genesis of the newt Triturus pyrrhogaster were studied with electron microscopic autoradiography. Isolated ectodermal and mesodermal tissues from the embryos were treated in H3-uridine for 3 hours and cultured in cold solution for various periods before fixation with OsO4 and embedding in Epon. At the blastula stage, the only structural component of the nucleus seen in electron micrographs is a mass of chromatin fibrils. At the early gastrula stage, the primary nucleoli originate as small dense fibrous bodies within the chromatin material. These dense fibrous nucleoli enlarge during successive developmental stages by the acquisition of granular components 150 A in diameter, which form a layer around them. Simultaneously larger granules (300 to 500 A) appear in the chromatin, and they fill the interchromatin spaces by the tail bud stage. Autoradiographic examination has demonstrated that nuclear RNA synthesis takes place in both the nucleolus and the chromatin, with the former consistently showing more label per unit area than the latter. When changes in the distribution pattern of radioactivity were studied 3 to 24 hours after immersion in isotope at each developmental stage, the following results were obtained. Labeled RNA is first localized in the fibrous region of the nucleolus and in the peripheral region of chromatin material. After longer culture in non-radioactive medium, labeled materials also appear in the granular region of the nucleolus and in the interchromatin areas. Further incubation gives labeling in cytoplasm. 相似文献
12.
13.
In an attempt to understand the significance of predation in the evolution of prey species, the ecological and morphological
characteristics of bacterial species under predation by a ciliated protozoa,Cyclidium sp., were investigated. Serial transfer at 7 day intervals was applied to the bacterial populations in the presence or absence
ofCyclidium. Although cells of the parental bacterial strain are typically short rods up to 1.5 μm long, cells of much greater length,
up to 20 μm long (type L) were found in populations exposed to predation fromCyclidium. However, the wildtype, shorter length bacteria persisted even after the appearance of type L. Type L was not observed in
the singl bacterial culture throughout the serial transfers. Type L appeared to improve the ability to escape predation by
elongating cell size, but growth rate and saturation density were decreased. 相似文献
14.
Hiroko Soda Shigenori Yukizane Ichiro Yoshida Yasutoshi Koga Shuichi Aramaki Hirohisa Kato 《Human genetics》1996,97(4):435-437
We have analyzed two unrelated Japanese patients with carbonic anhydrase II deficiency born to consanguineous parents. We
have identified the same mutation as that reported to be homozygous in a Belgian family and compound heterozygous in an American
family. It comprises to C-to-T transition that results in the amino acid substitution of Tyr (TAT) for His (CAT) at position
107. This point mutation creates an AccI site that can be conveniently screened by the polymerase chain reaction/restriction fragment length polymorphism method
using a restriction enzyme for gene tracking. Our patients exhibit severe mental retardation, not seen in the Belgian and
American patients.
Received: 23 November 1994 / Revised: 22 May 1995 相似文献
15.
Shuichi Matsumura Yasuyoshi Kinta Kazuya Sakiyama Kazunobu Toshima 《Biotechnology letters》1996,18(11):1335-1340
Summary Alkyl -D-xylobioside and alkyl -D-xyloside were prepared by the one-pot reaction of xylan and a fatty alcohol, such as 1-octanol, 1-decanol, 2-octanol and 2-ethylhexanol using the cell-free culture filtrate of the xylan-assimilating strain, Aureobasidium pullulans KK415. Using this strain, a novel surfactant, alkyl -D-xylobioside, was produced as the main product when the alcohol and xylan was incubated at a temperature of 65 °C and pH 4.5. 相似文献
16.
We have analyzed the esterase D (EsD) polymorphism at the nucleic acid level. Two common alleles, EsD1 and EsD2, are characterized by the substitution of one amino acid (Gly-to-Glu), which is caused by the point mutation of one nucleotide (G-to-A). Individuals exhibiting the EsD1 and EsD 2 phenotypes are homozygotes for EsD 1 and EsD 2 cDNAs, respectively. Individuals showing the EsD 2-1 phenotype have two kinds of cDNAs, viz., EsD 1 and EsD 2. The point mutation difference between the cDNAs of the EsD1 and EsD2 alleles results in a different SspI digestion site. A restriction fragment length polymorphism caused by this difference with respect to the SspI digestion site makes it possible to determine the EsD phenotype using DNA samples extracted from forensic materials with no EsD enzymatic activity. 相似文献
17.
Shuichi Yano 《Population Ecology》1994,36(1):63-71
This report shows that one of the most important roles of the flower nectar of an autogamous perennialRorippa indica (L.) Hieron is as an attractant for employing some ant species as a defense against herbivorous insects. The plant has flowers from spring to early winter. Its flower nectar is frequently stolen by some ant species (hereafter cited as ants) which also feed on small herbivorous insects on the plant. Internations among the tritrophic levels (R. indica, herbivores, ants) were experimentally examined and the followings became clear. (1) Ants were attracted toR. indica in search of its flower nectar. (2) The gradual secretion of flower nectar seemed to detain ants on the plant. (3)Pieris butterfly lavae were the major herbivores onR. indica and were potentially harmful to the plant. (4) The presence of ants reduced the survival rate ofP. rapae larvae onR. indica. (5) The presence of ants reduced the feeding damage toR. indica. (6) The disadvantage of nectar use by ants seemed to be minimal for the plant since the ants did not disturb the other flower visitors. These facts suggest a mutualistic relationship betweenR. indica and ants. That is, the flower nectar serves as an indirect defense against herbivorous insects. 相似文献
18.
Michael D. Browning Shuichi Endo Geoffrey B. Smith Ellen M. Dudek Richard W. Olsen 《Neurochemical research》1993,18(1):95-100
Previous work has shown that the GABAA-receptor (GABAA-R) could be phosphorylated by cAMP-dependent protein kinase (PKA), protein kinase C (PKC), and a receptor associated kinase. However, no clear picture has yet emerged concerning the particular subunit subtypes of the GABAA-R that were phosphorylated by PKA and PKC. In the present report we show that an antibody raised against a 23 amino acid polypeptide corresponding to a sequence in the putative intracellular loop of the 1 subunit of the receptor blocks the in vitro phosphorylation of the purified receptor by PKA and PKC. Moreover, N-terminal sequence analysis of the principal phosphopeptide fragment obtained after proteolysis of the receptor yielded a sequence that corresponds to the 3 subunit of the receptor. Such data provide additional support for our hypothesis (Browning et al., 1990, Proc. Natl. Acad. Sci. USA 87:1315–1317) that both PKA and PKC phosphorylate the -subunit of the GABAA-R.Special issue dedicated to Dr. Paul Greengard. 相似文献
19.
Fossil wood assemblages deposited during 6.300–3.000 yBP, are studied at the Akayama Site, central Japan. Layer III containing
fossil woods was divided into three subunits according to intercalating tephras, and total 3618 fossil woods were studied.
In the composition, deciduous broad-leaved trees dominated, accompanied by some evergreen conifers. In the diameter distribution,
nine taxa accounted for nearly 90% of individuals exceeding 10 cm in diameter. Spatial distribution of nine major and three
minor taxa and that of thick individuals clarified the following points: 1)Fraxinus established a lowland forest during 5,000–4,500 yBP, accompanied byAlnus sect.Gymnothyrsus, Acer andAesculus turbinata; 2) small trees ofAlnus sect.Gymnothyrsus extensively intermingled in the lowlandFraxinus forest during 4,500–3,000 yBP; 3)Quercus sect.Prinus and Castanea crenata constituted escarpment forests during 6,300–3,000 yBP; 4)Carpinus sect.Eucarpinus became a major component during 5,000–4,500 yBP, andOstrya japonica replacedCastanea crenata during 4,500–3,000 yBP. Comparison with the other five contemporaneous fossil wood assemblages shows prevalence ofFraxinus-dominant forests during the Late to Latest Jomon Periods in the southern part of the Kanto Plain. 相似文献
20.
Nishijima K Hisatsune T Kato H Kohyama M Kakehi M Hachimura S Kaminogawa S 《Cytotechnology》1997,25(1-3):89-100
Feeding of a whole casein diet, which abolished the αs1-casein-specific proliferation and IFN-γ productivity of CD4+ T cells, did not affect the proliferative response of CD8+ T cells with regard to the antigen dose response, cell dose response, kinetics of the proliferation and epitope specificity,
as well as IFN-γ production. To assess the characteristics of the CD8+ T cells, we established αs1-casein-specific CD8+ T cell clones from both casein-fed and control mice. The established clones produced different amount of IFN-γ and IL-10,
and one clone derived from the casein-fed mice produced a remarkable amount of IL-10. The clones from casein-fed mice produced
considerable amounts of TGF-β, while those from control mice produced only small amounts. The possible role of CD8+ T cells in oral tolerance is discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献