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991.
Nathan Mise Takashi Sado Masako Tada Shuji Takada Nobuo Takagi 《Experimental cell research》1996,223(2):193
Mouse embryonal carcinoma (EC) cell lines are divided into two classes with or without the capability of reactivating the inactive X chromosome from a fusion partner of female lymphocyte. The 5′ region ofXistwas partially methylated in reactivating-competent EC cells but was fully methylated in reactivating-incompetent EC cells having a single X chromosome. Partial or heterogeneous methylation implies methylation of each CpG site in about half of the cell independently of methylation status of neighboring CpG sites. Fusion of the reactivating-competent EC cells with female lymphocytes induced not onlyde novomethylation in the 5′ region ofXistallele on the hitherto inactivated X chromosome, but also demethylation of the same region ofXiston the other X chromosome from the female somatic cell. In contrast, no such changes occurred in hybrid cells involving reactivating-incompetent EC cells. Thus, partial methylation of the 5′ region ofXistmost probably maintained by low maintenance and highde novomethylation efficiency is correlated with reactivation potential of the EC cell. It is possible that this unique methylation pattern is implicated in random X inactivation in EC-hybrid cellsin vitroand in epiblast cellsin vivo. 相似文献
992.
Nobuo Moriyama Shigeharu Kurimoto Shigeo Horie Kimio Nasu Teruo Tanaka Kenichi Yano Hiroshi Hirano Gozo Tsujimoto Kazuki Kawabe 《The Histochemical journal》1996,28(4):283-288
Summary Adrenergic stimulation induces contraction of hypertrophied prostatic tissue via the α1 adrenoceptor, and the results of pharmacological studies suggested the existence of adrenoceptor subtypes. Recently three
subtypes (α1a, α1b, and α1d) were cloned. Using probes for these subtypes, we demonstrated their expression in the tissues of ten cases of benign prostatic
hypertrophy, usingin situ hybridization. To determine the ratio between these subtypes, an RNase protection assay was also performed in three cases.
Expression of the α1a and α1d adrenoceptors was diffuse in the smooth muscles of the interstitium, but was absent in glandular epithelial cells. On the
contrary, the α1b adrenoceptor was hardly detectable. The RNase protection assay confirmed the absence of the α1b adrenoceptor, the ratio of α1a and α1d being 4∶1. These results supported the idea that the differences in prostatic contractile response to several adrenergic
drugs are based on the affinities of these drugs for the different subtypes. 相似文献
993.
Glutathione Efflux from Cultured Astrocytes 总被引:8,自引:6,他引:2
Abstract: The characteristics and kinetics of GSH efflux from the monolayer culture of rat astrocytes were investigated. GSH efflux was dependent on temperature, with a Q 10 value of 2.0 between 37 and 25°C. The GSH efflux rate showed a hyperbolic dependency on the intracellular GSH concentration. The data were fitted well to the Michaelis-Menten model, giving the following kinetic parameter values: K m = 127 nmol/mg of protein; V max = 0.39 nmol/min/mg of protein. p -Chloromercuribenzenesulfonic acid, a thiol-reactive agent impermeable to the cell membrane, lowered the GSH efflux rate by 25% without affecting the intracellular GSH content. These results suggest that a carrier is involved in the efflux of GSH. The GSH content of cultured astrocytes showed a marked increase when the cells were exposed to insults, such as sodium arsenite, cadmium chloride, and glucose/glucose oxidase that lead to the generation of hydrogen peroxide. The increase in GSH content was attributed to the induction of the cystine transport activity by the agents. Although the intracellular GSH concentration and GSH efflux were increased, the kinetics of GSH efflux were not affected by those agents that imposed the oxidative stress. Because the K m value is very large, it is suggested that astrocytes release GSH depending on their GSH concentration in a wide range. 相似文献
994.
B. -S. Seo P. A. Peterson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(1-2):151-163
The transposition of the maize transposable element Enhancer (En) had been focused on one chromosome 3 for several generations. From the a1-m(Au) allele with an autonomous En, a new En reporter allele a1-m(r)3927-1, was isolated that undergoes very infrequent and late excision events, producing one or two small spots in the aleurone. This allele is seriously impaired in its capacity to excise. Coincident with the origin of this allele, an En was located at a site close to the a1 locus. From this initial insertion site, the movement of this En was followed for three to four generations in 974 families with a higher transposition rate of this En (50% of the testcross progeny) than that found in a previous study of En transposition. This is the first case reported where a particular En was followed for more than three generations. The higher rate of wanderings of this En along the same chromosome led to the term vagabond En (En
vag
). Genetic evidence that En may transpose from a replicated donor site to an unreplicated site is provided. Speculative mechanisms on the origin of a1-m(r)3927-1 and En
vag
are discussed.Journal Paper No. J-15864 of Iowa Agricultural and Iowa Economical Experiment Station Project #3176 相似文献
995.
Induction of Salicylic Acid {beta}-Glucosidase in Tobacco Leaves by Exogenous Salicylic Acid 总被引:2,自引:0,他引:2
Salicylic acid (SA) has been proposed to be an endogenous signalfor systemic acquired resistance to infection by pathogens inplants. In general, most SA is found in an inactive form asSA ß-glucoside (SAG). SAG seems to be a storage formof SA from which bioactive SA can be generated. Recent reportsindicate that ß-glucosidase might be involved in regulatingthe signaling activity of phytohormones. Therefore, it seemslikely that SA ß-glucosidase, the enzyme that hydrolyzesSAG to yield free SA, might also play an important role by regulatingthe level of free SA. Since hydrolysis of SAG seems to occurin intercellular spaces, we attempted to isolate SA ß-glucosidaseactivity from the intercellular spaces of SA-treated tobaccoleaves, where we found considerable amounts of the enzymaticactivity. Furthermore, increased levels of SA and SA ß-glucosidaseactivity were found in the leaves after treatment with exogenousSA. The role of SA ß-glucosidase in plant defensesystems is discussed. (Received November 15, 1994; Accepted January 20, 1995) 相似文献
996.
997.
Nobuo Takemori Katsuyuki Hirai Ryuichi Onodera Nagahito Saito 《Cell and tissue research》1995,281(1):69-76
Granules consisting of periodically arranged membranous lamellae and amorphous electron-opaque material, i.e., periodic lamellar granules, are present in human neutrophils. To date, no extensive ultrastructural studies have been carried out on these granules because of their infrequent presence in neutrophils. The bone marrow of 18 cases of chronic myeloproliferative disorders, including one case of chronic neutrophilic leukemia in which periodic lamellar granules were frequently seen in neutrophils, was investigated by electron microscopy. Periodic lamellar granules were seen in neutrophils in 12 of the 18 cases at varying frequencies. They were preferentially seen in immature neutrophils. The transverse profiles of these granules revealed concentric complete/incomplete rings or periodic parallel straight lines, i.e., various patterns of lamellar arrangement were present. Periodic lamellar granules were positive for myeloperoxidase and lysozyme at the electron-microscopic level. These results suggest that these granules represent a primary neutrophil granule subtype. However, their functional and pathologic significance remains unknown. 相似文献
998.
Kohji Egawa Naohiro Seo Takae Tanino Tomomi Tsukiyama 《Cancer immunology, immunotherapy : CII》1995,41(6):384-388
Q5 antigens are expressed on the surface of various experimental murine tumor cells. They share partially common antigenicity with Qa-2 alloantigens expressed on normal lymphocytes. For that reason we tested the immunoprotection by anti-Qa-2 immunization of mice against a Q5+ tumor. Nerve fibrosarcoma (NSFA) tumor, which specifically develops metastasis in the lung, has been reported to be poorly immunogenic. However, expression of the Q5 antigen was evident on the surface of NFSA cells. After immunizing (C3H/He x B6.K1)F1 (Qa-2-) mice with B6 (Qa-2+) lymphocytes, the protection against the proliferation of the semi-syngeneic NFSA tumor was examined First, immunization of normal mice induced resistance to NFSA cell transplants. Second, when the tumor cells were transplanted to the hind foot of a mouse and the resulting tumor was removed by amputating the leg, the mice were protected against the development of lung metastasis after immunization by intraperitoneal inoculation of B6 cells 3 days after tumor removal. Immunization with attenuated NFSA cells in this system failed to protect the mice from lung metastasis. On the other hand, inoculation of the mice with B6 cells without removal of the original tumor on the foot showed little effect on the progression of the tumor. Thus, cytotoxic T lymphocytes (CTL), which seemed to be present in an inactive form in the mice from which the tumor had not been removed, were induced in the mice after the removal of the major tumor followed by immunization with B6 lymphocytes. The induction of CTL by the immunization was suppressed in mice bearing large tumors. Cells stimulated by the tumor antigen seemed to be involved in the suppression. It was also shown that the Q5 antigen is the direct recognition target of the CTL since the activity of Q5-specific CTL clones in lysing tumor cells was inhibited by a monoclonal antibody specific for the Q5 antigen. In contrast to immunization with attenuated tumor cells, our novel allogeneic lymphocyte immunization procedure offers high CTL activation, by-passing the induction of T cell unresponsiveness. 相似文献
999.
Nagase Takahiro; Miyajima Nobuyuki; Tanaka Ayako; Sazuka Takashi; Seki Naohiko; Sato Shusei; Tabata Satoshi; Ishikawa Ken-ichi; Kawarabayasi Yutaka; Kotani Hirokazu; Nomura Nobuo 《DNA research》1995,2(1):37-43
We isolated full-length cDNA clones from size-fractionated cDNAlibraries of human immature myeloid cell line KG-1, and thecoding sequences of 40 genes were newly predicted. A computersearch of the GenBank/EMBL databases indicated that the sequencesof 14 genes were unrelated to any reported genes, while theremaining 26 genes carried some sequences with similaritiesto known genes. Significant transmembrane domains were identifiedin 17 genes, and protein motifs that matched those in the PROSITEmotif database were identified in 11 genes. Northern hybridizationanalysis with 18 different cells and tissues demonstrated that10 genes were apparently expressed in a cell-specific or tissue-specificmanner. Among the genes predicted, half were isolated from themedium-sized cDNA library and the other half from the small-sizedcDNA library, and their average sizes were 4 kb and 1.4 kb,respectively. As judged by Northern hybridization profiles,small-sized cDNAs appeared to be expressed more ubiquitouslyand abundantly in various tissues, compared with that of medium-sizedcDNAs. 相似文献
1000.