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901.
Topological patterns in the development and evolution of metazoa, from sponges to chordates, are considered by means of previously
elaborated methodology, with the genus of the surface used as a topological invariant. By this means metazoan morphogenesis
may be represented as topological modification(s) of the epithelial surfaces of an animal body. The animal body surface is
an interface between an organism and its environment, and topological transformations of the body surface during metazoan
development and evolution results in better distribution of flows to and from the external medium, regarded as the source
of nutrients and oxygen and the sink of excreta, so ensuring greater metabolic intensity. In sponges and some Cnidaria, the
increase of this genus up to high values and the shaping of topologically complicated fractal-like systems are evident. In
most Bilateria, a stable topological pattern with a through digestive tube is formed, and the subsequent topological complications
of other systems can also appear. The present paper provides a topological interpretation of some developmental events through
the use of well-known mathematical concepts and theorems; the relationship between local and global orders in metazoan development,
i.e., between local morphogenetic processes and integral developmental patterns, is established. Thus, this methodology reveals
a “topological imperative”: A certain set of topological rules that constrains and directs biological morphogenesis. 相似文献
902.
SIN1/MIP1 maintains rictor-mTOR complex integrity and regulates Akt phosphorylation and substrate specificity 总被引:23,自引:0,他引:23
Mammalian target of rapamycin (mTOR) controls cell growth and proliferation via the raptor-mTOR (TORC1) and rictor-mTOR (TORC2) protein complexes. Recent biochemical studies suggested that TORC2 is the elusive PDK2 for Akt/PKB Ser473 phosphorylation in the hydrophobic motif. Phosphorylation at Ser473, along with Thr308 of its activation loop, is deemed necessary for Akt function, although the regulatory mechanisms and physiological importance of each phosphorylation site remain to be fully understood. Here, we report that SIN1/MIP1 is an essential TORC2/PDK2 subunit. Genetic ablation of sin1 abolished Akt-Ser473 phosphorylation and disrupted rictor-mTOR interaction but maintained Thr308 phosphorylation. Surprisingly, defective Ser473 phosphorylation affected only a subset of Akt targets in vivo, including FoxO1/3a, while other Akt targets, TSC2 and GSK3, and the TORC1 effectors, S6K and 4E-BP1, were unaffected. Our findings reveal that the SIN1-rictor-mTOR function in Akt-Ser473 phosphorylation is required for TORC2 function in cell survival but is dispensable for TORC1 function. 相似文献
903.
Panero J Trelles J Rodano V Montserrat JM Iglesias LE Lewkowicz ES Iribarren AM 《Biotechnology letters》2006,28(14):1077-1081
Enzymatic hydrolysis of acetylated nucleosides using microbial whole cells has been carried out for the first time. Unlike Candida antarctica B lipase-catalysed alcoholysis, none of the tested microorganisms displayed a common deacetylation profile. Depending on the substrate and the biocatalyst used, 5′-selective deprotection or mixtures of mono O-acetylated products were obtained. 相似文献
904.
We review the synthesis and photophysical properties of light harvesting phenylacetylene dendrimers with unsymmetrical branching.
We describe the steady state and time dependent experiments that are used to characterize energy transfer properties in the
conjugated dendrimers. Finally, we describe investigations of the unsymmetrical phenylacetylene dendrimers as potential materials
for applications in fluorescence-based sensors, and for non-linear optics. 相似文献
905.
Simoni D Rizzi M Rondanin R Baruchello R Marchetti P Invidiata FP Labbozzetta M Poma P Carina V Notarbartolo M Alaimo A D'Alessandro N 《Bioorganic & medicinal chemistry letters》2008,18(2):845-849
Using concepts of bioisostery a series of curcumin analogs were synthesized: the diketonic system of the compound was elaborated into enaminones, oximes, and the isoxazole heterocycle. The cell growth inhibitory and apoptosis inducing effects of the new analogs were evaluated by in vitro assays in the hepatocellular carcinoma HA22T/VGH cells, as well as in the MCF-7 breast cancer cell line and in its multidrug resistant (MDR) variant MCF-7R. Increased antitumor activity on all cell lines was found with the isoxazole analog and especially with the benzyl oxime derivative; in the HA22T/VGH cell model, the latter compound inhibited constitutive NF-kappaB activation. 相似文献
906.
Bromidge SM Bertani B Borriello M Faedo S Gordon LJ Granci E Hill M Marshall HR Stasi LP Zucchelli V Merlo G Vesentini A Watson JM Zonzini L 《Bioorganic & medicinal chemistry letters》2008,18(20):5653-5656
Investigation of a series 6-[2-(4-aryl-1-piperazinyl)ethyl]-2H-1,4-benzoxazin-3(4H)-ones has led to the discovery of potent 5-HT(1A/1B/1D) receptor antagonists with and without additional SerT affinity. Modulation of the different target activities gave compounds with a range of profiles suitable for further in vivo characterization. 相似文献
907.
Sara Di Toro Giulio Zanaroli Giovanna Cristina Varese Valeria Filipello Marchisio Fabio Fava 《International biodeterioration & biodegradation》2008,62(2):153-161
The biodegradability of two commercial diesel fuels, i.e., Diesel and HiQ Diesel, herewith designated as G1 and G2, respectively, spiked to an agricultural soil at 10 g kg−1 was studied under aerobic slurry-phase conditions in the absence and in the presence of Enzyveba, i.e., a characterized commercial source of microorganisms and nutrients. A quite similar hydrocarbon composition was displayed by G1 and G2, which were found to be both extensively and almost completely biodegraded under all conditions after 4.5 months of treatment with a remarkable depletion of initial soil ecotoxicity, in particular in the G2 spiked one. The addition of Enzyveba resulted in a higher availability of cultivable specialized bacteria and fungi in the reactors but this only resulted in a slight intensification of soil bioremediation, probably because of the high contents of nutrients and indigenous specialized microorganisms of the soil. A faster biodegradation of hydrocarbons and a more rapid and extensive depletion of initial ecotoxicity were generally observed in the soil reactors spiked with G2 with respect to those spiked with G1 probably for the G2 content of additives capable of improving hydrocarbons bioavailability. 相似文献
908.
909.
Wang L Pozzato V Turato G Madamanchi A Murphy TM Chitano P 《American journal of physiology. Lung cellular and molecular physiology》2008,294(5):L964-L973
Airway smooth muscle (ASM) from infant guinea pigs has less spontaneous relaxation during stimulation than ASM from adults. Inhibition of cyclooxygenase (COX), which catalyzes the production of prostanoids, increases this relaxation in infant ASM and abolishes age differences, thus suggesting that prostanoids reduce relaxation in infant ASM. In this study, we investigated whether leukotrienes are also involved in reducing spontaneous relaxation; whether the two COX isoforms, COX-1 and COX-2, differentially regulate spontaneous relaxation; and whether prostanoid release is developmentally regulated in guinea pig ASM. In different age groups, we measured relaxation during and after electrical stimulation in tracheal strips as well as prostanoid release from tracheal segments. Relaxation was studied in the absence and in the presence of a lipoxygenase inhibitor, a cysteinyl leukotriene receptor-1 antagonist, a COX-1 inhibitor, or a COX-2 inhibitor. We found that inhibition of lipoxygenase or cysteinyl leukotriene receptor-1 antagonism did not increase spontaneous relaxation at any age, thus excluding a role for leukotrienes in this phenomenon. Inhibition of COX-2, but not COX-1, promoted spontaneous relaxation. The basal release of prostanoids was more abundant in tissue from infant animals and decreased significantly with age. Thromboxane B2 was the most abundant metabolite released at all ages. Electrical stimulation and epithelium removal did not affect the age difference in prostanoid release. We conclude that increased basal prostanoid release contributes to the reduced spontaneous relaxation in immature guinea pig ASM compared with older animals. By regulating ASM relaxation, prostanoids may play a role in the airway hyperresponsiveness at a young age. 相似文献
910.
Collakova E Goyer A Naponelli V Krassovskaya I Gregory JF Hanson AD Shachar-Hill Y 《The Plant cell》2008,20(7):1818-1832
In prokaryotes, PurU (10-formyl tetrahydrofolate [THF] deformylase) metabolizes 10-formyl THF to formate and THF for purine and Gly biosyntheses. The Arabidopsis thaliana genome contains two putative purU genes, At4g17360 and At5g47435. Knocking out these genes simultaneously results in plants that are smaller and paler than the wild type. These double knockout (dKO) mutant plants show a 70-fold increase in Gly levels and accumulate elevated levels of 5- and 10-formyl THF. Embryo development in dKO mutants arrests between heart and early bent cotyledon stages. Mature seeds are shriveled, accumulate low amounts of lipids, and fail to germinate. However, the dKO mutant is only conditionally lethal and is rescued by growth under nonphotorespiratory conditions. In addition, culturing dKO siliques in the presence of sucrose restores normal embryo development and seed viability, suggesting that the seed and embryo development phenotypes are a result of a maternal effect. Our findings are consistent with the involvement of At4g17360 and At5g47435 proteins in photorespiration, which is to prevent excessive accumulation of 5-formyl THF, a potent inhibitor of the Gly decarboxylase/Ser hydroxymethyltransferase complex. Supporting this role, deletion of the At2g38660 gene that encodes the bifunctional 5,10-methylene THF dehydrogenase/5,10-methenyl THF cyclohydrolase that acts upstream of 5-formyl THF formation restored the wild-type phenotype in dKO plants. 相似文献