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991.
Fc{epsilon}RI-mediated mast cell degranulation requires calcium-independent microtubule-dependent translocation of granules to the plasma membrane
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Nishida K Yamasaki S Ito Y Kabu K Hattori K Tezuka T Nishizumi H Kitamura D Goitsuka R Geha RS Yamamoto T Yagi T Hirano T 《The Journal of cell biology》2005,170(1):115-126
The aggregation of high affinity IgE receptors (Fc receptor I [FcRI]) on mast cells is potent stimulus for the release of inflammatory and allergic mediators from cytoplasmic granules. However, the molecular mechanism of degranulation has not yet been established. It is still unclear how FcRI-mediated signal transduction ultimately regulates the reorganization of the cytoskeleton and how these events lead to degranulation. Here, we show that FcRI stimulation triggers the formation of microtubules in a manner independent of calcium. Drugs affecting microtubule dynamics effectively suppressed the FcRI-mediated translocation of granules to the plasma membrane and degranulation. Furthermore, the translocation of granules to the plasma membrane occurred in a calcium-independent manner, but the release of mediators and granule–plasma membrane fusion were completely dependent on calcium. Thus, the degranulation process can be dissected into two events: the calcium-independent microtubule-dependent translocation of granules to the plasma membrane and calcium-dependent membrane fusion and exocytosis. Finally, we show that the Fyn/Gab2/RhoA (but not Lyn/SLP-76) signaling pathway plays a critical role in the calcium-independent microtubule-dependent pathway. 相似文献
992.
Kawatani Y Igarashi H Matsui T Kuwahara K Fujimura S Okamoto N Takagi K Sakaguchi N 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(9):5615-5618
Double-stranded DNA breaks (DSBs) at the IgV region (IgV) genes might be involved in somatic hypermutation and affinity-maturation of the B cell receptor in response to T cell-dependent Ag. By ligation-mediated PCR, we studied IgV DSBs that occurred in mature germinal center B cells in response to nitrophenyl-chicken gamma-globulin in a RAG1-independent, Ag-dependent, and IgV-selective manner. We quantified their levels in GANP-deficient B cells that have impaired generation of high-affinity Ab. GANP-/- B cells showed a decreased level of DSBs with blunt ends than control B cells and, on the contrary, the ganp gene transgenic (GANPTg) B cells showed an increased level. These results suggested that the level of IgV DSBs in germinal center B cells is associated with GANP expression, which is presumably required for B cell receptor affinity maturation. 相似文献
993.
RNAi-mediated silencing of OsGEN-L (OsGEN-like), a new member of the RAD2/XPG nuclease family, causes male sterility by defect of microspore development in rice 总被引:11,自引:0,他引:11
Moritoh S Miki D Akiyama M Kawahara M Izawa T Maki H Shimamoto K 《Plant & cell physiology》2005,46(5):699-715
We have cloned a new member of the RAD2/XPG nuclease family, OsGEN-L (OsGEN-like), from rice (Oryza sativa L.). OsGEN-L possesses two domains, the N- and I-regions, that are conserved in the RAD2/XPG nuclease family. Database searches and phylogenetic analyses revealed that OsGEN-L belongs to class 4 of the RAD2/XPG nuclease family, and OsGEN-L homologs were found in animals and higher plants. To elucidate the function of OsGEN-L, we generated rice OsGEN-L-RNAi transgenic plants in which OsGEN-L expression was silenced. Most of the OsGEN-L-RNAi plants displayed low fertility, and some of them were male-sterile. OsGEN-L-RNAi plants lacked mature pollen, resulting from a defect in early microspore development. A OsGEN-L-green fluorescent protein (GFP) fusion protein was localized in the nucleus, and the OsGEN-L promoter was specifically active in the anthers. Furthermore, a recombinant OsGEN-L protein possessed flap endonuclease activity and both single-stranded and double-stranded DNA-binding activities. Our results suggest that OsGEN-L plays an essential role in DNA metabolism required for early microspore development in rice. 相似文献
994.
Kannan Tharakaraman Satoru Watanabe Kuan Rong Chan Jia Huan Vidya Subramanian Yok Hian Chionh Aditya Raguram Devin Quinlan Megan McBee Eugenia Z. Ong Esther S. Gan Hwee Cheng Tan Anu Tyagi Shashi Bhushan Julien Lescar Subhash G. Vasudevan Eng Eong Ooi Ram Sasisekharan 《Cell host & microbe》2018,23(5):618-627.e6
995.
Shuichi Asano Satoru Ito Mika Morosawa Kishio Furuya Keiji Naruse Masahiro Sokabe Etsuro Yamaguchi Yoshinori Hasegawa 《Biochemistry and Biophysics Reports》2018
Activation of airway smooth muscle (ASM) cells plays a central role in the pathophysiology of asthma. Because ASM is an important therapeutic target in asthma, it is beneficial to develop bioengineered ASM models available for assessing physiological and biophysical properties of ASM cells. In the physiological condition in vivo, ASM cells are surrounded by extracellular matrix (ECM) and exposed to mechanical stresses such as cyclic stretch. We utilized a 3-D culture model of human ASM cells embedded in type-I collagen gel. We further examined the effects of cyclic mechanical stretch, which mimics tidal breathing, on cell orientation and expression of contractile proteins of ASM cells within the 3-D gel. ASM cells in type-I collagen exhibited a tissue-like structure with actin stress fiber formation and intracellular Ca2+ mobilization in response to methacholine. Uniaxial cyclic stretching enhanced alignment of nuclei and actin stress fibers of ASM cells. Moreover, expression of mRNAs for contractile proteins such as α-smooth muscle actin, calponin, myosin heavy chain 11, and transgelin of stretched ASM cells was significantly higher than that under the static condition. Our findings suggest that mechanical force and interaction with ECM affects development of the ASM tissue-like construct and differentiation to the contractile phenotype in a 3-D culture model. 相似文献
996.
Monoclonal antibodies (mAbs) of the IgG class produced by mouse hybridomas raised with NS-1 myelomas have been shown to contain
two types of immunoglobulin light (κ) chains derived from the myelomas and antigen-stimulated spleen lymphocytes, and the
hybridomas produce three mAb species with light chain heterogeneity (Abe and Inouye, 1993). In the present study, 9 hybridoma
lines secreting homogeneous mAbs have been isolated from 63 lines cloned from an established hybridoma line producing three
mAbs. They secrete homogeneous mAbs containing light chains derived from either myeloma or spleen cells. They contain either
κ gene derived from the respective cells, and the other gene was deleted during the cultivation. The deletion frequency of
the κ gene of myelomas is 3 times higher than that of spleen cells, although 80–85% of hybridomas reach the stable state containing
both κ genes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
997.
Conformation of an Shc-derived phosphotyrosine-containing peptide complexed with the Grb2 SH2 domain
Kenji Ogura Shigeo Tsuchiya Hiroaki Terasawa Satoru Yuzawa Hideki Hatanaka Valsan Mandiyan Joseph Schlessinger Fuyuhiko Inagaki 《Journal of biomolecular NMR》1997,10(3):273-278
We have determined the structure of an Shc-derivedphosphotyrosine-containing peptide complexed with Grb2 SH2 based on intra-and intermolecular NOE correlations observed by a series of isotope-filteredNMR experiments using a PFG z-filter. In contrast to an extendedconformation of phosphotyrosine-containing peptides bound to Src, Syp andPLC SH2s, the Shc-derived peptide formed a turn at the +1 and +2positions next to the phosphotyrosine residue. Trp121, locatedat the EF1 site of Grb2 SH2, blocked the peptide binding in an extendedconformation. The present study confirms that eachphosphotyrosine-containing peptide binds to the cognate SH2 with a specificconformation, which gives the structural basis for the binding specificitybetween SH2s and target proteins. 相似文献
998.
999.
The role of the human small heat shock protein (HSP27) in oxidative stress was examined using stable transformants of an immortalized human fibroblast cell line (KMST-6) isolated by transfection of HSP27 expression vectors. Several stable transformants that expressed high or low levels of HSP27 protein were obtained. Clones expressing high levels of HSP27 were more sensitive to growth inhibition by a low dose of hydrogen peroxide (0.1 mM) than those expressing low levels. Clones expressing high levels of HSP27 did not acquire obvious resistance to hyperthermy and cytotoxic agents, except for one (#13), in which resistance to cytotoxic agents was increased. The level of phosphorylated HSP27 in clones expressing high levels of this protein increased at 30 min and was sustained even 4 hours after exposing the cells to 0.1 mM of hydrogen peroxide. On the other hand, the levels in clones expressing low levels of HSP27 were reduced within 4 hours after exposure to hydrogen peroxide. Furthermore, overexpression of nonphosphorylatable mutant HSP27 did not affect sensitivity to oxidative stress. These results suggested that constitutively high expression of HSP27 in KMST-6 cells make them susceptible to oxidative stress resulting in growth arrest, and this mechanism could involve the phosphorylation of HSP27. © 1995 Wiley-Liss, Inc. 相似文献
1000.
Hidetaka Noritomi Motokazu Miyata Satoru Kato Kunio Nagahama 《Biotechnology letters》1995,17(12):1323-1328
Summary The peptide synthesis from N-acetyl-L-tyrosine ethyl ester (Ac-Tyr-OEt) and amino acid amides was realized using -chymotrypsin (CT) in acetonitrile (MeCN) or acetonitrile/supercritical carbon dioxide (SCCO2) containing small amounts of water. In both solvent systems there was an optimum water content for peptide synthesis, above which peptide hydrolysis became more important. After an incubation for 5 hours, the yields of the peptide was 64% in MeCN and 91% in MeCN/SCCO2, respectively. 相似文献