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991.
Hiroshi Fujimoto Megumi Isomura Tatsuo Miyazaki Ichiro Matsuo Richard Walton Tohru Sakakibara Katsumi Ajisaka 《Glycoconjugate journal》1997,14(1):75-80
GlcNAc1-2Man and GlcNAc1-6Man were synthesized using the reverse hydrolysis activity of -N-acetylglucosaminidase from both jack beans and Bacillus circulans. In turn, Gal1-4GlcNAc1-2Man and Gal1-4GlcNAc1-6Man were synthesized regioselectively using the transglycosylation activity of -galactosidase from Diplococcus pneumoniae and B. circulans, respectively. These di- and trisaccharides are important components of complex type sugar chains and will be used as intermediates in our synthetic studies. Abbreviations: pNp--GlcNAc, p-nitrophenyl 2-acetamido-2-deoxy--D-glucopyranoside; pNp--Gal, p-nitrophenyl -D-galacto-pyranoside 相似文献
992.
Pyruvate:ferredoxin oxidoreductase was purified to electrophoretic homogeneity from an aerobic, thermophilic, obligately
chemolithoautotrophic, hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6, by precipitation with ammonium sulfate and fractionation by DEAE-Sepharose CL-6B, polyacrylate-quaternary amine, hydroxyapatite,
and Superdex-200 chromatography. The native enzyme had a molecular mass of 135 kDa and was composed of four different subunits
with apparent molecular masses of 46, 31.5, 29, and 24.5 kDa, respectively, indicating that the enzyme has an αβγδ-structure.
The activity was detected with pyruvate, coenzyme A, and one of the following electron acceptors in substrate amounts: ferredoxin
isolated from H. thermophilus, FAD, FMN, triphenyltetrazolium chloride, or methyl viologen. NAD, NADP, and ferredoxins from Chlorella spp. and Clostridium pasteurianum were ineffective as the electron acceptor. The temperature optimum for pyruvate oxidation was approximately 80° C. The pH
optimum was 7.6–7.8. The apparent K
m values for pyruvate and coenzyme A at 70° C were 3.45 mM and 54 μM, respectively. The enzyme was extremely thermostable under
anoxic conditions; the time for a 50% loss of activity (t
50%) at 70° C was approximately 8 h.
Received: 9 September 1996 / Accepted: 27 December 1996 相似文献
993.
Masahiko Yamamoto Takeshi Yasuda Kiyoshi Hayasaka A. Ohnishi Hiroo Yoshikawa Takehiko Yanagihara Tohru Ikegami Tatsunori Yamamoto Hirofumi Ohashi Tomoya Nishimura Terunori Mitsuma Hidenori Kiyosawa Phillip F. Chance G. Sobue 《Human genetics》1997,100(2):151-154
We have used human β2 and β4 cDNA probes to map the genes encoding two isoforms of the regulatory β subunit of voltage-activated
Ca2+ channels, viz. CACNB2 (β2) and CACNB4 (β4), to human chromosomes 10p12 and 2q22-q23, respectively, by fluorescence in situ
hybridization. The gene encoding the β2 protein, first described as a Lambert-Eaton myasthenic syndrome (LEMS) antigen in
humans, is found close to a region that undergoes chromosome rearrangements in small cell lung cancer, which occurs in association
with LEMS. CACNB2 (β2) and CACNB4 (β4) genes are members of the ion-channel gene superfamily and it should now be possible
to examine their loci by linkage analysis of ion-channel-related disorders. To date, no such disease-related gene has been
assigned to 10p12 and 2q22-q23.
Received: 5 February 1997 / Accepted: 4 April 1997 相似文献
994.
Tohru Miyoshi-Akiyama Wakae Fujimaki Xao-Jie Yan Junji Yagi Ken'ichi Imanishi Hidehito Kato Kyuhei Tomonari Takehiko Uchiyama 《Microbiology and immunology》1997,41(4):345-352
We previously reported that Yersinia pseudotuberculosis-derived mitogen (YPM) acts as a superantigen to human T cells. In this study, we assessed the superantigenicity and toxicity of YPM using murine experimental models. YPM activated T cells to produce interleukin-2 in a major histocompatibility complex class II molecule-dependent manner. The T-cell blasts induced by YPM expressed T-cell receptor (TCR) β-chain variable region (Vβ)7, VβS.1, Vβ8.2 and Vβ8.3. The injection of YPM into mice pre-sensitized with D-galactosamine induced lethal shock. This shock was blocked by the injection of monoclonal antibodies (mAbs) to CD4, TCR Vβ7 plus Vβ8, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), but not by injection to CD8 or unrelated Vβ. These results indicate that YPM-induced shock requires the presence of CD4+ T cells bearing TCR Vβ7 and Vβ8, and that endogenous TNF-a and IFN-γ mediate the lethal effects. 相似文献
995.
Nanako Takeda-Hirokawa Lian-pin Neoh Hiroaki Akimoto Hiroshi Kaneko Takashi Hishikawa Iwao Sekigawa Hiroshi Hashimoto Shun-ichi Hirose Tsutomu Murakami Naoki Yamamoto Tohru Mimura Yutaro Kaneko 《Microbiology and immunology》1997,41(9):741-745
To clarify the mechanism by which curdlan sulfate (CRDS) inhibits human immunodeficiency virus (HIV)-1 infection, we examined its influence on the binding of gp120 to CD4 molecules on T cells and macrophages, as well as on the production of TNF-α by gp120-stimulated macrophages (which promotes HIV-1 replication). CRDS treatment of cells not only inhibited the binding of HIV-1 gp120 to CD4+ cells, but also inhibited TNF-α production induced by gp120. Inhibition of HIV-1 infection by CRDS may be related to these two actions. 相似文献
996.
William Ba-Thein Satoko Inui Tohru Shimizu Tint Swe Sayera Banu Kaori Ohtani Misari Oe Naomi Sakurai Shinichi Nakamura Hideo Hayashi 《Microbiology and immunology》1997,41(8):629-631
The genomic structure of the pfoA-colA region in six theta-toxin-deficient strains of Clostridium perfringens was examined by Southern hybridization using the pfoR, pfoA, pbg, arcABDC and colA genes, encoding regulator for pfoA, theta-toxin, beta-galactosidase, arginine metabolism enzymes and kappa-toxin, respectively, as gene probes. It is suggested that the productivity of theta-toxin in these strains is diverse because of the multiple genetic backgrounds including single deletion of pfoA, large deletion of the pfoA-colA region and the putative point mutations. 相似文献
997.
The reproductive allocation (allocation of net production to acorns) of a tall tree speciesQuercus serrata was estimated by a method combining branch diameter distribution and the sampling of acorns per branch. Acorn production
per branch of 0.5-cm diameter significantly varied among individuals and years, but not significantly across tree size. Leaf
production per branch of 0.5-cm diameter had little annual fluctuation, while that of acorns fluctuated about 6 times between
the maximum and minimum. The reproductive allocation was regressed against vegetative allocation, following the general model
of klinkhameret al. (1992); the reproduction had a beginning threshold and reproductive allocation increased drastically at relatively young
stage after the tree began reproduction. With its small threshold production, coppicing traits and large maximum size,Q. serrata seemed adaptive to infrequent but large-scale disturbances like fires. 相似文献
998.
H. Hashimoto H. Toyohara Y. Yokoyama † M. Sakaguchi K. Ozato ‡ Y. Wakamatsu ‡ 《Journal of fish biology》1997,50(1):201-207
The culture medium supplemented with carp serum and fetal bovine serum (FBS) promoted cell growth significantly and induced morphological change of goldfish fin cells in early passage as compared to the medium containing FBS alone. However, these effects were not observed in RBCF-1, a cell line established from the goldfish fin. The sensitivity of the cells in early passage to carp serum suggests the following possibilities: (1) cells in early passage retain the ability to respond to growth-promoting factors specifically included in carp serum; and (2) this ability is lost during the process of long-term culture and/or long-term culture in FBS eliminates cell groups showing high dependency of cell growth on carp serum. 相似文献
999.
Hiroyuki Ishikawa Hajime Hisaeda Yoichi Maekawa Hideyuki Nagasawa Tohru Sakai Fusao Ota Kunisuke Himeno 《Parasitology international》1997,46(4):263-270
We studied the relationship between the expression of 65-kDa heat shock protein (HSP65) and resistance of mice to infection with Leishmania major (L. major), an obligate intracellular protozoan. C57BL/6 (B6) mice, a strain genetically resistant to L. major infection, expressed high level of HSP65 in their peritoneal and draining lymph node macrophages after infection, whereas susceptible BALB/c mice expressed only slightly at the early stage of infection. This protein was not expressed in the parasite itself and macrophages of non-infected mice. We examined the role of T cells in the expression of HSP65 by using SCID mice grafted with the fetal thymus from B6 or BALB/c mice (B6-TG or BALB-TG mice, respectively). Either BALB-TG or B6-TG mice were reconstituted with T cells derived from each grafted fetal thymus. B6-TG mice were markedly resistant against infection with L. major, compared with BALB-TG mice. Furthermore, the HSP65 expression in macrophages of thymus-grafted mice was similar to that of the thymus-donor type. That is, B6-TG mice expressed a high level of this protein, whereas BALB-TG mice did in lower level than B6-TG mice. These results show that T cells are necessary to express HSP65 and the expression correlates with a protective potential of T cells against infection with L. major. 相似文献
1000.
Kensei Kobayashi Hisako Tonishi Taiki Tsuboi Nobushige Suzuki Takeo Kaneko Yoshinori Takano Yasuo Yasuyuki Muramatsu Hirofumi Hashimoto Masamichi Yamashita 《Biological Sciences in Space》2004,18(3):179-180
Complex organic compounds have been found in extraterrestrial bodies such as meteorites and comets. We confirmed the formation of complex organic compounds that contained amino acid precursors from a mixture of carbon monoxide (or methanol), ammonia and water by radiation or UV. Molecular weights of the complex organics were several thousands. Stability of the complex precursors was studied. When free amino acids were irradiated with gamma rays or synchrotron radiation, they easily decomposed. The complex precursors were, however, much more stable than free amino acid against irradiation. We propose to examine the formation and alteration of amino acid precursors in space by using exposed facility of ISS. 相似文献