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221.
Piao WH Wong R Bai XF Huang J Campagnolo DI Dorr RT Vollmer TL Shi FD 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(11):7415-7423
The side effects of cancer chemotherapeutic agents such as mitoxantrone (MIT) in multiple sclerosis (MS) patients justify the search for less toxic drugs. Ethonafide is an anthracene-based antineoplastic drug similar to MIT. With reference to MIT, we examined the effect of ethonafide on experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice, an animal model of human MS. We demonstrated that ethonafide is effective in preventing development of EAE as well as in ameliorating the severity of EAE when disease is ongoing. In relatively higher dosages, the effects of ethonafide and MIT on EAE were identical, whereas in lower dosages, MIT seemed more effective. Therapeutic effects of ethonafide were associated with the initial reduction in cellular counts of CD3(+), CD4(+), CD8(+), B220(+), CD11b(+), NK cells, and NKT cells, followed by recovery of these cells from the bone marrow. Interestingly, the recovered autoreactive T cells in ethonafide-treated animals have reduced capacity to expand and produce cytokines in response to myelin Ag stimulation. Furthermore, CD4(+)CD25(+) regulatory T cells were relatively resistant to depletion and/or recovered faster than T effector cells. The ability of regulatory T cells to resist depletion and replenish quickly during cell ablation therapy may provide an opportunity to reprogram the immune system. Moreover, we provided evidences that ethonafide has less cardiac toxicity compared with MIT. The effectiveness and the low cardiotoxicity of ethonafide might make it a promising immunosuppressive agent for clinical use in treating MS patients. 相似文献
222.
When calf thymus chromatin is incubated with protamine, the protein binds to DNA, forming a chromatin-protamine complex. The binding reaches a saturating level at the weight ratio of protamine to DNA of approximately 0.5. Although the saturated binding of protamine to DNA does not cause major displacement of histones from calf thymus chromatin, examination of the dissociation profiles by salt in combination with urea of protamine-treated chromatin shows that the histone-DNA interactions are markedly altered by such binding. The dissociation of histones from the chromatin-protamine complex requires less NaCl but the same concentration of urea as that for untreated chromatin, suggesting that the electorstatic interactions between the histones and DNA are decreased as a result of protamine binding. When protamine concentration is increased beyond that required for saturated binding to DNA during in vitro exposure of calf thymus chromatin to protamine, lysine-rich histone is completely displaced. 相似文献
223.
Yu B Yang M Wong HY Watt RM Song E Zheng BJ Yuen KY Huang JD 《Applied microbiology and biotechnology》2011,91(1):177-188
Live attenuated Salmonella enterica serovar Typhi Ty21a (Ty21a) is an important vaccine strain used in clinical studies for typhoid fever and as a vaccine vector
for the expression of heterologous antigens. To facilitate the use of Ty21a in such studies, it is desirable to develop improved
strategies that enable the stable chromosomal integration and expression of multiple heterologous antigens. The phage λ Red
homologous recombination system has previously been used in various gram-negative bacteria species to mediate the accurate
replacement of regions of chromosomal DNA with PCR-generated ‘targeting cassettes’ that contain flanking regions of shared
homologous DNA sequence. However, the efficiency of λ Red-mediated recombineering in Ty21a is far lower than in Escherichia coli and other Salmonella typhimurium strains. Here, we describe an improved strategy for recombineering-based methods in Ty21a. Our reliable and efficient method
involves the use of linear DNA-targeting cassettes that contain relatively long flanking ‘arms’ of sequence (ca. 1,000 bp)
homologous to the chromosomal target. This enables multiple gene-targeting procedures to be performed on a single Ty21a chromosome
in a straightforward, sequential manner. Using this strategy, we inserted three different influenza antigen expression cassettes
as well as a green fluorescent protein gene reporter into four different loci on the Ty21a chromosome, with high efficiency
and accuracy. Fluorescent microscopy and Western blotting analysis confirmed that strong inducible expression of all four
heterologous genes could be achieved. In summary, we have developed an efficient, robust, and versatile method that may be
used to construct recombinant Ty21a antigen-expressing strains. 相似文献
224.
Drosophila melanogaster and its close relatives are used extensively in comparative biology. Despite the importance of phylogenetic information for such studies, relationships between some melanogaster species group members are unclear due to conflicting phylogenetic signals at different loci. In this study, we use twelve nuclear loci (eleven coding and one non-coding) to assess the degree of phylogenetic incongruence in this model system. We focus on two nodes: (1) the node joining the Drosophila erecta-Drosophila orena, Drosophila melanogaster-Drosophila simulans, and Drosophila yakuba-Drosophila teissieri lineages, and (2) the node joining the lineages leading to the melanogaster, takahashii, and eugracilis subgroups. We find limited evidence for incongruence at the first node; our data, as well as those of several previous studies, strongly support monophyly of a clade consisting of D. erecta-D. orena and D. yakuba-D. teissieri. By contrast, using likelihood based tests of congruence, we find robust evidence for topological incongruence at the second node. Different loci support different relationships among the melanogaster, takahashii, and eugracilis subgroups, and the observed incongruence is not easily attributable to homoplasy, non-equilibrium base composition, or positive selection on a subset of loci. We argue that lineage sorting in the common ancestor of these three subgroups is the most plausible explanation for our observations. Such lineage sorting may lead to biased estimation of tree topology and evolutionary rates, and may confound inferences of positive selection. 相似文献
225.
Tai EK Wu WK Wong HP Lam EK Yu L Cho CH 《Experimental biology and medicine (Maywood, N.J.)》2007,232(6):799-808
Cathelicidin, an antimicrobial peptide of the innate immune system, modulates microbial growth, wound healing, and inflammation. However, its association with inflammatory bowel diseases (IBDs) is unknown. Our objective was to determine whether cathelicidin would exert a modulatory effect on the progression of IBD and, if so, investigate the mechanism of action through which this effect occurred. We evaluated the potential for a synthetic cathelicidin, the mouse cathelin-related antimicrobial peptide (mCRAMP), to prevent the initiation and promote the healing of lesions from inflammatory colitis that was experimentally induced in mice with dextran sulfate sodium (DSS). During the experiment, mCRAMP was given: (i) as a parallel treatment starting together with 3% DSS feeding, and (ii) as a posttreatment starting 7 days after 3% DSS feeding. The body weight, fecal microflora populations, clinical symptoms, and histologic findings of colonic tissues were measured. Relative gene expression of mucins (MUC1, MUC2, MUC3, and MUC4) in colonic tissues was determined by real-time polymerase chain reaction. Intrarectal administration of mCRAMP ameliorated DSS-induced colitis with negligible effects on mucosal healing. The peptide also significantly reduced the increased number of fecal microflora in colitis animals. It reversed the decline of colonic mucus thickness during colitis through upregulation of the expression of mucin genes. Treatment with mCRAMP also prevented colitis development by suppressing the induction of apoptosis by DSS. The current study demonstrates for the first time that intrarectal administration of cathelicidin may be a novel therapeutic option for IBDs. 相似文献
226.
Selvapandiyan A Kumar P Morris JC Salisbury JL Wang CC Nakhasi HL 《Molecular biology of the cell》2007,18(9):3290-3301
Centrin is a calcium-binding centrosome/basal body-associated protein involved in duplication and segregation of these organelles in eukaryotes. We had shown that disruption of one of the centrin genes (centrin1) in Leishmania amastigotes resulted in failure of both basal body duplication and cytokinesis. Here, we undertook to define the role of centrin1 (TbCen1) in the duplication and segregation of basal body and its associated organelles kinetoplast and Golgi, as well as its role in cytokinesis of the procyclic form of Trypanosoma brucei by depleting its protein using RNA inhibition methodology. TbCen1-depleted cells showed significant reduction in growth compared with control cells. Morphological analysis of these cells showed they were large and pleomorphic with multiple detached flagella. Both immunofluorescence assays using organelle-specific antibodies and electron microscopic analysis showed that TbCen1-deficient cells contained multiple basal bodies, kinetoplasts, Golgi, and nuclei. These multiple organelles were, however, closely clustered together, indicating duplication without segregation in the absence of centrin. This failure in organelle segregation may be the likely cause of inhibition of cytokinesis, suggesting for the first time a new and unique role for centrin in the segregation of organelles without affecting their multiplication in the procyclic form of T. brucei. 相似文献
227.
228.
Effect of Phloroglucinol and Resorcinol on the Clingstone Peach Polyphenol Oxidase-catalyzed Oxidation of 4-Methylcatechol 下载免费PDF全文
Phloroglucinol and resorcinol are not substrates for clingstone peach (Prunus persica) polyphenol oxidase, but they react with 4-methyl-o-quinone, produced either enzymatically or nonenzymatically, to give an intense red or red-brown color with a maximal absorption at about 470 nanometers. Several colored products were isolated from an ethyl acetate extract of the reaction by two-dimensional thin layer chromatography. Based on thin layer chromatographic and spectral studies of the enzymatic and nonenzymatic reactions, polyphenol oxidase does not play a role in the reaction between 4-methyl-o-quinone and phloroglucinol, resorcinol, d-catechin, or orcinol. In such reactions, the function of polyphenol oxidase is the formation of 4-methyl-o-quinone which then reacts nonenzymatically with the above phenols. Activation energies of both enzymatic and nonenzymatic reactions were determined. 相似文献
229.
Vince JE Wong WW Khan N Feltham R Chau D Ahmed AU Benetatos CA Chunduru SK Condon SM McKinlay M Brink R Leverkus M Tergaonkar V Schneider P Callus BA Koentgen F Vaux DL Silke J 《Cell》2007,131(4):682-693
XIAP prevents apoptosis by binding to and inhibiting caspases, and this inhibition can be relieved by IAP antagonists, such as Smac/DIABLO. IAP antagonist compounds (IACs) have therefore been designed to inhibit XIAP to kill tumor cells. Because XIAP inhibits postmitochondrial caspases, caspase 8 inhibitors should not block killing by IACs. Instead, we show that apoptosis caused by an IAC is blocked by the caspase 8 inhibitor crmA and that IAP antagonists activate NF-kappaB signaling via inhibtion of cIAP1. In sensitive tumor lines, IAP antagonist induced NF-kappaB-stimulated production of TNFalpha that killed cells in an autocrine fashion. Inhibition of NF-kappaB reduced TNFalpha production, and blocking NF-kappaB activation or TNFalpha allowed tumor cells to survive IAC-induced apoptosis. Cells treated with an IAC, or those in which cIAP1 was deleted, became sensitive to apoptosis induced by exogenous TNFalpha, suggesting novel uses of these compounds in treating cancer. 相似文献
230.
Microbial modification of naturally occurring materials is one of the efficient ways to add new values to them. Hydroxylation
of free unsaturated fatty acids by microorganism is a good example of those modifications. Among microbial strains studied
for that purpose, a new bacterial isolate Pseudomonas aeruginosa PR3 has been well studied to produce several hydroxy fatty acids from different unsaturated fatty acids. Of those hydroxy
fatty acids, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) was efficiently produced from oleic acid by strain PR3. However, it was highly plausible to use
vegetable oil containing oleic acid rather than free oleic acid as a substrate for DOD production by strain PR3. In this study,
we firstly tried to use olive oil containing high content of oleic acid as a substrate for DOD production. DOD production
from olive oil was confirmed by structural determination with GC, TLC, and GC/MS analysis. DOD production yield from olive
oil was 53.5%. Several important environmental factors were also tested. Galactose and glutamine were optimal carbon and nitrogen
sources, and magnesium ion was critically required for DOD production from olive oil. Results from this study demonstrated
that natural vegetable oils containing oleic acid could be used as efficient substrate for the production of DOD by strain
PR3. 相似文献