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491.
The structure of a diterpenoid, designated salvigresin, that was isolated from the aerial parts of Salvia greggii, has been confirmed by spectroscopic investigation and X-ray analysis. 相似文献
492.
Restriction of amino acid change in influenza A virus H3HA: comparison of amino acid changes observed in nature and in vitro 总被引:5,自引:0,他引:5 下载免费PDF全文
We introduced 248 single-point amino acid changes into hemagglutinin (HA) protein of the A/Aichi/2/68 (H3N2) strain by a PCR random mutation method. These changes were classified as positive or negative according to their effect on hemadsorption activity. We observed following results. (i) The percentage of surviving amino acid changes on the HA1 domain that did not abrogate hemadsorption activity was calculated to be ca. 44%. In nature, it is estimated to be ca. 39.6%. This difference in surviving amino acid changes on the HA protein between natural isolates and in vitro mutants might be due to the immune pressure against the former. (ii) A total of 26 amino acid changes in the in vitro mutants matched those at which mainstream amino acid changes had occurred in the H3HA1 polypeptide from 1968 to 2000. Of these, 25 were positive. We suggest that the majority of amino acid changes on the HA protein during evolution might be restricted to those that were positive on the HA of A/Aichi/2/68. (iii) We constructed two-point amino acid changes on the HA protein by using positive mutants. These two-point amino acid changes with a random combination did not inhibit hemadsorption activity. It is possible that an accumulation of amino acid change might occur without order. (iv) From the analysis of amino acids participating in mainstream amino acid change, each antigenic site could be further divided into smaller sites. The amino acid substitutions in the gaps between these smaller sites resulted in mostly hemadsorption-negative changes. These gap positions may play an important role in maintaining the function of the HA protein, and therefore amino acid changes are restricted at these locations. 相似文献
493.
Furuta K Tohno Y Tohno S Moriwake Y Minami T Takano Y Azuma C Takakura Y 《Biological trace element research》2003,95(2):123-137
Because zinc attenuates endothelial cell dysfunction that proceeds atherosclerosis, depressed zinc status may be involved
in the initiation of endothelial dysfunction. However, before recommending a zinc-enriched diet to reduce the risks for atherosclerosis,
the effect of excess zinc on endothelial cell functions in normozincemic status should be known. Therefore, in this study,
the effect of dietary zinc on normal endothelial cell functions in animals subjected to a diet containing 334±58 ppm zinc
for 30 d was studied to see whether supplemented zinc has an effect on endothelial cells. Despite a slight increase in blood
zinc, unaltered aortic and kidney zinc contents were associated with unchanged blood pressure in rats subjected to a zinc-enriched
diet. Increased basal nitric oxide and prostacyclin were accompanied by a normal response to phenylephrine. Dietary zinc influenced
neither endothelial-dependent nor endothelial-independent relaxations significantly. However, it elevated the share of M1-type
cholinoceptor response as well as dilator prostaglandin release, which seems to be nitric oxide dependent. There was a strong
correlation (r=0.826, p<0.05) between M1-type cholinoceptor response and prostacyclin release in zinc-treated rings. These results suggested that
zinc ions increases M1-mediated prostacyclin release in normal endothelial cells without altering intracellular pathways. 相似文献
494.
495.
The technique of proteome analysis with two-dimensional PAGE has the power to monitor global changes that occur in the protein expression of tissues and organisms and/or expression that occurs under stresses. In this study, the catalogues of the rice proteome were constructed, and a functional characterization of some of these proteins was examined. Proteins extracted from tissues of rice and proteins extracted from rice under various kinds of stress were separated by two-dimensional PAGE. An image analyzer was used to reveal a total of 10,589 protein spots on 10 kinds of two-dimensional PAGE gels stained by Coomassie Brilliant Blue. The separated proteins were electroblotted onto a polyvinylidene difluoride membrane, and the N-terminal amino acid sequences of 272 of 905 proteins were determined. The internal amino acid sequences of 633 proteins were determined using a protein sequencer or mass spectrometry after enzyme digestion of the proteins. Finally, a data file of rice proteins that included information on amino acid sequences and sequence homologies was constructed. The major proteins involved in the growth and development of rice can be identified using the proteome approach. Some of these proteins, including a calcium-binding protein that turned out to be calreticulin and a gibberellin-binding protein, which is ribulose-1,5-bisphosphate carboxylase/oxygenase activase in rice, have functions in the signal transduction pathway. The information thus obtained from the rice proteome will be helpful in predicting the function of the unknown proteins and will aid in their molecular cloning. 相似文献
496.
Matsui T Kondo T Nishita Y Itadani S Tsuruta H Fujita S Omawari N Sakai M Nakazawa S Ogata A Mori H Ohno H Obata T Nakai H Toda M 《Bioorganic & medicinal chemistry letters》2002,12(6):907-910
Metabolic stabilization of the chemical lead 1, which is a structurally novel inhibitor of TNF-alpha production, was accomplished by introducing a (1S)-methyl group into the optically active backbone. As a result, 2, 3 and 4 were identified as drug candidates and evaluated pharmacologically. The analysis of an active conformer was also carried out. 相似文献
497.
Molecular cloning, genomic structure, and expression analysis of MUC20, a novel mucin protein, up-regulated in injured kidney 总被引:9,自引:0,他引:9
498.
Kise K Nakagawa M Okamoto N Hanato T Watanabe N Nishijima S Fujino H Takeuchi Y Shiraishi I 《Birth defects research. Part A, Clinical and molecular teratology》2005,73(8):547-554
BACKGROUND: Congenital heart defects, including conotruncal anomalies, are often associated with arrhythmias. Bis-diamine induces conotruncal anomalies in embryos when administered to pregnant female rats. To investigate the mechanism of arrhythmia in conotruncal anomalies, we histologically examined the development of the cardiac conduction system in this animal model. METHODS: A single dose of 200 mg of bis-diamine was administered to pregnant Wistar rats on ED 10.5 of pregnancy. The embryos were removed on each day from ED 11.5 to 15.5. Immunoexpression of HNK-1, connexin40, and connexin43 were examined in serial sections. The distribution pattern of TUNEL-positive cells around the conduction system was also examined. RESULTS: HNK-1 immunoreactivity was evident in interventricular septum, in both the control and the bis-diamine-treated embryos from ED 12.5. Although a chain of connexin40-immunoreactive cells from interventricular septum to trabeculae, corresponding to the His bundle and its branches, was demonstrated at ED 13.5 in the control embryos, this chain was first detected at ED 14.5 in the bis-diamine-treated embryos. Immunoexpression of connexin43 in the working myocardium was also less in the bis-diamine-treated embryos than in the control at ED 13.5. The number of TUNEL-positive cells in the interventricular septum was highest at ED 12.5 in the control and at ED 13.5 in the bis-diamine-treated embryos. Furthermore, these TUNEL-positive cells were HNK-1 negative, vimentin-positive, and alpha smooth muscle actin-positive. CONCLUSIONS: Bis-diamine disturbed the normal development of gap junctions and apoptosis of myofibroblasts around the HNK-1-positive conduction tissue through overall poor myocardial proliferation and growth. 相似文献
499.
Two types of red pigment, anthocyanins and betacyanins, never occur together in the same plant. Although anthocyanins are widely distributed in higher plants as flower and fruit pigments, betacyanins have replaced anthocyanins in the Caryophyllales. We isolated cDNAs encoding dihydroflavonol 4-reductase (DFR), which is the first enzyme committed to anthocyanin biosynthesis in the flavonoid pathway, from Spinacia oleracea and Phytolacca americana, plants that belong to the Caryophyllales. The deduced amino acid sequence of Spinacia DFR and Phytolacca DFR revealed a high degree of homology with DFRs of anthocyanin-producing plants. The DFR of carnation, an exception in the Caryophyllales that synthesizes anthocyanin, showed the highest level of identity. In the phylogenetic tree, Spinacia DFR and Phytolacca DFR clustered with the DFRs of anthocyanin-synthesizing dicots. Recombinant Spinacia and Phytolacca DFRs expressed in Escherichia coli convert dihydroflavonol to leucoanthocyanidin. The expression and function of DFR in spinach and pokeweed are discussed in relation to the molecular evolution of red pigment biosynthesis in higher plants. 相似文献
500.
This study investigates the influence of exogenously applied abscisic acid (ABA) on the leaves and leaf sheaths of two-week-old rice seedling at the level of the proteome. Significant differences were observed in the two-dimensional polyacrylamide gel electrophoresis protein profiles between control and ABA treated samples. Amino-acid sequence analysis of affected proteins revealed that ABA caused drastic changes in the major photosynthetic protein, ribulose 1,5-bisphosphate carboxylase/oxygenase and accumulation of certain defense/stress-related proteins. Moreover, cutting or treating leaf sheaths with jasmonic acid (JA) rapidly increased the endogenous level of ABA, suggesting a role for ABA during the defense/stress-response. Comparative study indicated a potential overlap between ABA and JA as detected at the level of the proteome. Furthermore, in vitro protein phosphorylation experiments and in-gel kinase assays also revealed considerable changes in the phosphorylation status of some proteins, and differential effects on myelin basic protein and calcium-dependent protein kinase activities by ABA treatment, which suggests involvement of kinase in the downstream signaling cascade. These results provide evidence at proteome level for the involvement of ABA in stress-response in rice seedling. 相似文献