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71.
Implementing a recall paradigm without hypnosis, we use functional MRI (fMRI) to explore and compare nociceptive and centrally-driven pain experiences. We posit that a trace of a recent nociceptive event can be used to create sensory-re-experiencing of pain that can be qualified in terms of intensity and vividness. Fifteen healthy volunteers received three levels of thermal stimuli (warm, low pain and high pain) and subsequently were asked to recall and then rate this experience. Neuroimaging results reveal that recalling a previous sensory experience activates an extensive network of classical pain processing structures except the contralateral posterior insular cortex. Nociceptive-specific activation of this structure and the rated intensity difference between physical and recalled pain events allow us to investigate the link between the quality of the original nociceptive stimulus and the mental trace, as well as the differences between the accompanying neural responses. Additionally, by incorporating the behavioural ratings, we explored which brain regions were separately responsible for generating either an accurate or vivid recall of the physical experience. Together, these observations further our understanding of centrally-mediated pain experiences and pain memory as well as the potential relevance of these factors in the maintenance of chronic pain. 相似文献
72.
Abnormal B-cell responses to chemokines, disturbed plasma cell localization, and distorted immune tissue architecture in Rgs1-/- mice
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Normal lymphoid tissue development and function depend upon chemokine-directed cell migration. Since chemokines signal through heterotrimeric G-protein-coupled receptors, RGS proteins, which act as GTPase-activating proteins for Galpha subunits, likely fine tune the cellular responses to chemokines. Here we show that Rgs1(-/-) mice possess B cells that respond excessively and desensitize improperly to the chemokines CXCL12 and CXCL13. Many of the B-cell follicles in the spleens of Rgs1(-/-) mice have germinal centers even in the absence of immune stimulation. Furthermore, immunization of these mice leads to exaggerated germinal center formation; partial disruption of the normal architecture of the spleen and Peyer's patches; and abnormal trafficking of immunoglobulin-secreting cells. These results reveal the importance of a regulatory mechanism that limits and desensitizes chemokine receptor signaling. 相似文献
73.
Kadlcik V Sicard-Roselli C Mattioli TA Kodicek M Houee-Levin C 《Free radical biology & medicine》2004,37(6):881-891
Amyloid beta peptide (Abeta) is a 39 to 43 amino-acid-long peptide implicated in Alzheimer's disease. One of its mechanisms of toxicity is related to its redox properties. Therefore we studied its one electron oxidation using azide free radicals produced in gamma and pulse radiolysis, and compared the results with those obtained with the reverse sequence Abeta(40-1). HPLC analysis combined with absorption, fluorescence, Raman spectroscopy, and MALDI-TOF MS were used for product identification. Met35 was shown to be the target in Abeta(1-40); oxidation leads to a major compound that is Abeta with methionine sulfoxide. Similarly, oxidation of fragment Abeta(29-40) also leads to methionine sulfoxide. For Abeta(40-1), Met35 is not reactive and Tyr10 is the target of azide radicals. The major products are peptide dimer linked by dityrosine and trimer. The lowering of the one-electron reduction potential of the MetS+/Met couple, which was proposed, is in agreement with our findings. To our knowledge, this is the first time that such a drastic effect of the primary sequence is observed in a small peptide. In addition, it is also the first experimental demonstration of the sensitivity of the one-electron reduction potential of methionine on neighboring groups. 相似文献
74.
Devillers N Farmer C Mounier AM Le Dividich J Prunier A 《Reproduction, nutrition, development》2004,44(4):381-396
Blood, colostrum and saliva samples were serially taken from 6 multiparous sows from day 109 of gestation until day 3 postpartum. Plasma was assayed for oestradiol-17beta (E2), progesterone (P4), prolactin (PRL), cortisol, immunoglobulin G (IgG) and lactose. Colostrum was assayed for E2, P4, IgG and lactose. Lactoserum, obtained after ultra centrifugation of colostrum, was assayed for PRL. Saliva was assayed for cortisol. Time-related variations in hormone, IgG and lactose concentrations measured in plasma were parallel to those measured in colostrum, lactoserum or saliva. However, the concentrations were higher in colostrum or lactoserum and lower in saliva than in plasma. Ratios of concentrations of cortisol in saliva and PRL in lactoserum over those in plasma did not vary with time and averaged 0.2 and 1.6, respectively. Conversely, the ratios of concentrations of E2 and P4 in colostrum over those in plasma varied with time (P < 0.05) but were quite constant before the end of parturition, averaging 2.7 and 3.6, respectively. The ratios of concentrations of IgG and lactose in colostrum over those in plasma also varied with time (P < 0.05). The concentrations of hormones in plasma on the one hand and in colostrum, lactoserum or saliva on the other hand were significantly correlated but correlations varied with time (PRL across periods: r = 0.31; cortisol across periods: r = 0.60; E2 during parturition: r = 0.83; P4 before parturition: r = 0.82; P4 during parturition: r = 0.67). The present results indicate that around parturition, assays of hormones in colostrum or saliva can be used to study the hormonal status of sows. Furthermore, variations in colostrum and plasma concentrations of IgG and lactose are good indicators of the transition from colostrum to milk synthesis. 相似文献
75.
Maamar H Valette O Fierobe HP Bélaich A Bélaich JP Tardif C 《Molecular microbiology》2004,51(2):589-598
Progress towards understanding the molecular basis of cellulolysis by Clostridium cellulolyticm was obtained through the study of the first cellulolysis defective mutant strain, namely cipCMut1. In this mutant, a 2 659 bp insertion element, disrupts the cipC gene at the sequence encoding the seventh cohesin of the scaffoldin CipC. cipC is the first gene in a large 'cel' gene cluster, encoding several enzymatic subunits of the cellulosomes, including the processive cellulase Cel48F, which is the major component. Physiological and biochemical studies showed that the mutant strain was affected in cellulosome synthesis and severely impaired in its ability to degrade crystalline cellulose. It produced small amounts of a truncated CipC protein (P120), which had functional cohesin domains and assembled complexes which did not contain any of the enzymes encoded by genes of the 'cel' cluster. The mutant cellulolytic system was mainly composed of three proteins designated P98, P105 and P125. Their N-termini did not match any of the known cellulase sequences from C. cellulolyticum. A large amount of entire CipC produced in the cipCMut1 strain by trans-complementation with plasmid pSOScipC did not restore the cellulolytic phenotype, in spite of the assembly of a larger amount of complexes. The complexes produced in the mutant and complemented strains contained at least 12 different dockerin-containing proteins encoded by genes located outside of the 'cel' cluster. The disturbances observed in the mutant and trans-complemented strains were the result of a strong polar effect resulting from the cipC gene disruption. In conclusion, this study provided genetic evidence that the cellulases encoded by the genes located in the 'cel' cluster are essential for the building of cellulosomes efficient in crystalline cellulose degradation. 相似文献
76.
The enzymatic composition of the cellulosomes produced by Clostridium cellulolyticum was modified by inhibiting the synthesis of Cel48F that is the major cellulase of the cellulosomes. The strain ATCC 35319 (pSOSasrF) was developed to over-produce a 469 nucleotide-long antisense-RNA (asRNA) directed against the ribosome-binding site region and the beginning of the coding region of the cel48F mRNAs. The cellulolytic system secreted by the asRNA-producing strain showed a markedly lower amount of Cel48F, compared to the control strain transformed with the empty plasmid (pSOSzero). This was correlated with a 30% decrease of the specific activity of the cellulolytic system on Avicel cellulose, indicating that Cel48F plays an important role in the recalcitrant cellulose degradation. However, only minor effects were observed on the growth parameters on cellulose. In both transformant strains, cellulosome production was found to be reduced and two unknown proteins (P105 and P98) appeared as major components of their cellulolytic systems. These proteins did not contain any dockerin domain and were shown to be not included into the cellulosomes; they are expected to participate to the non-cellulosomal cellulolytic system of C. cellulolyticum. 相似文献
77.
78.
Lepercq P Gérard P Béguet F Raibaud P Grill JP Relano P Cayuela C Juste C 《FEMS microbiology letters》2004,237(1):65-72
Several H2-producing fermentative anaerobic bacteria including Clostridium, Klebsiella and Fusobacteria degraded octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) (36 microM) to formaldehyde (HCHO) and nitrous oxide (N2O) with rates ranging from 5 to 190 nmol h(-1)g [dry weight] of cells(-1). Among these strains, C. bifermentans strain HAW-1 grew and transformed HMX rapidly with the detection of the two key intermediates the mononitroso product and methylenedinitramine. Its cellular extract alone did not seem to degrade HMX appreciably, but degraded much faster in the presence of H2, NADH or NADPH. The disappearance of HMX was concurrent with the release of nitrite without the formation of the nitroso derivative(s). Results suggest that two types of enzymes were involved in HMX metabolism: one for denitration and the second for reduction to the nitroso derivative(s). 相似文献
79.