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991.
W E Seaman M Sleisenger E Eriksson G C Koo 《Journal of immunology (Baltimore, Md. : 1950)》1987,138(12):4539-4544
Weekly injections of a monoclonal antibody (MAb) to the antigen NK-1.1 were used to sustain depletion of NK cells from the spleens of adult C57BL/6 mice for up to 8 wk. Mice depleted of NK cells in this manner had no lasting alteration in the distribution of other lymphocyte subsets in the spleen and did not demonstrate reduced cellular or humoral immunity. Depletion of NK cells, however, markedly increased the localization and growth of B16 melanoma cells or CT 38 colon carcinoma cells in the lung after i.v. administration of tumor cells. Moreover, mice given B16 tumors and treated with anti-NK-1.1 had reduced survival. NK cells were important in host resistance to sublines of B16 that had been passaged either in vivo or in vitro, which express, respectively, high and low levels of class I major histocompatibility antigens. These findings support a role for NK cells in host defense against malignancy. The ability to selectively remove NK cells in vivo by MAb will permit a better understanding of their physiologic role. 相似文献
992.
Choi IY Moon PD Koo HN Myung NY Kim SJ Lee JH Han SH Moon G Seo SY Sung HJ Park RK Jeong HJ Um JY Kim HM Hong SH 《In vitro cellular & developmental biology. Animal》2007,43(7):215-221
To explore effects of Forsythia koreana methanol extract (FKME) on mast cell-mediated allergic and inflammatory properties, the effect of FKME was evaluated on compound
48/80-induced systemic anaphylaxis, ear swelling, and anti-dinitrophenyl (DNP) immunoglobulin E (IgE)-induced passive cutaneous
anaphylaxis (PCA). In addition, the effect of FKME was investigated on the histamine release from rat peritoneal mast cells
(RPMCs) stimulated by compound 48/80, which promotes histamine release. The human mast cell line HMC-1 was stimulated by phorbol
12-myristate 13-acetate plus calcium ionophore A23187. Activated HMC-1 can produce several proinflammatory and chemotactic
cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-8. Cytokine levels in the culture supernatant
were measured by an enzyme-linked immunosorbent assay. Cytotoxicity by FKME was determined by a 3-(4,5-dimethylthiazol-2-yl)-diphenyl-tetrazolium
bromide (MTT) assay. FKME inhibited compound 48/80-induced systemic anaphylactic shock and ear swelling in mice. When 1 g/kg
FKME was pretreated or posttreated with mice, compound 48/80-induced mice morality was 50 and 66.7%, respectively. One gram
per kilogram of FKME pretreatment inhibited ear-swelling responses derived from compound 48/80 by 29.75%. A PCA reaction was
inhibited by 17.9%. In an in vitro model, FKME (1 mg/ml) inhibited histamine release from the RPMCs by 13.8% and TNF-α, IL-6,
and IL-8 production from HMC-1 cells by 71.16% (P < 0.001), 86.72% (P < 0.001), and 44.6%, respectively. However, FKME had no cytotoxic effects on cell viability. In conclusion, FKME inhibited
not only systemic anaphylaxis and ear swelling induced by compound 48/80 but also inhibited a PCA reaction induced by anti-DNP
IgE in vivo. Treatment with FKME showed significant inhibitory effects on histamine, TNF-α, IL-6, and IL-8 release from mast
cells. 相似文献
993.
Chun Hua Jin Yoon Mo Koo Dae-Ki Choi Kyung Ho Row 《Biotechnology and Bioprocess Engineering》2007,12(5):525-530
Here we investigate the chromatographic behavior, with reversed-phase high performance liquid chromatography (RP-HPLC) of
nucleic compounds (nucleobases, nucleosides, and nucleotides) on a C18 column in several different mobile phase additives, including1-butyl-3-methylimidazolium tetrafuloroborate ([BMIm][BF4]), 1-ethyl-3-methylimidazolium methylsulfate ([EMIm][MS]) ionic liquids, ammonium formate, and potassium phosphate. The effect
of the alkyl group length, the imidazolium ring, and the ionic liquid's counterions on retention and resolution of the samples
were tested. The results show the potential application of a used buffer system, ion pairing system, and ionic liquid as mobile
phase additives in liquid chromatography resolution of nucleic compounds. 相似文献
994.
Hypoxia-induced cell death of HepG2 cells involves a necrotic cell death mediated by calpain 总被引:2,自引:0,他引:2
Kim MJ Oh SJ Park SH Kang HJ Won MH Kang TC Hwang IK Park JB Kim JI Kim J Lee JY 《Apoptosis : an international journal on programmed cell death》2007,12(4):707-718
To elucidate mechanism of cell death in response to hypoxia, we attempted to compare hypoxia-induced cell death of HepG2 cells
with cisplatin-induced cell death, which has been well characterized as a typical apoptosis. Cell death induced by hypoxia
turned out to be different from cisplatin-mediated apoptosis in cell viability and cleavage patterns of caspases. Hypoxia-induced
cell death was not associated with the activation of p53 while cisplatin-induced apoptosis is p53 dependent. In order to explain
these differences, we tested involvement of μ-calpain and m-calpain in hypoxia-induced cell death. Calpains, especially μ-calpain,
were initially cleaved by hypoxia, but not by cisplatin. Interestingly, the treatment of a calpain inhibitor restored PARP
cleavage that was absent during hypoxia, indicating the recovery of activated caspase-3. The inhibition of calpains prevented
proteolysis induced by hypoxia. In addition, hypoxia resulted in a necrosis-like morphology while cisplatin induced an apoptotic
morphology. The calpain inhibitor prevented necrotic morphology induced by hypoxia and converted partially to apoptotic morphology
with nuclear segmentation. Our result suggests that calpains are involved in hypoxia-induced cell death that is likely to
be necrotic in nature and the inhibition of calpain switches hypoxia-induced cell death to apoptotic cell death without affecting
cell viability. 相似文献
995.
Background
Many studies implicate Arf6 activity in Rac-mediated membrane ruffling and cytoskeletal reorganization. Although Arf6 facilitates the trafficking of Rac1 to the plasma membrane and in many cases Arf6 activation leads to the activation of Rac1, the details of how Arf6 influences Rac function remain to be elucidated. 相似文献996.
Background
Scientific workflows improve the process of scientific experiments by making computations explicit, underscoring data flow, and emphasizing the participation of humans in the process when intuition and human reasoning are required. Workflows for experiments also highlight transitions among experimental phases, allowing intermediate results to be verified and supporting the proper handling of semantic mismatches and different file formats among the various tools used in the scientific process. Thus, scientific workflows are important for the modeling and subsequent capture of bioinformatics-related data. While much research has been conducted on the implementation of scientific workflows, the initial process of actually designing and generating the workflow at the conceptual level has received little consideration. 相似文献997.
Stolyar S He Q Joachimiak MP He Z Yang ZK Borglin SE Joyner DC Huang K Alm E Hazen TC Zhou J Wall JD Arkin AP Stahl DA 《Journal of bacteriology》2007,189(24):8944-8952
998.
999.
Adenylosuccinate lyase (ADL) catalyzes the breakdown of 5-aminoimidazole- (N-succinylocarboxamide) ribotide (SAICAR) to 5-aminoimidazole-4-carboxamide ribotide (AICAR) and fumarate, and of adenylosuccinate (ADS) to adenosine monophosphate (AMP) and fumarate in the de novo purine biosynthetic pathway. ADL belongs to the argininosuccinate lyase (ASL)/fumarase C superfamily of enzymes. Members of this family share several common features including: a mainly alpha-helical, homotetrameric structure; three regions of highly conserved amino acid residues; and a general acid-base catalytic mechanism with the overall beta-elimination of fumarate as a product. The crystal structures of wild-type Escherichia coli ADL (ec-ADL), and mutant-substrate (H171A-ADS) and -product (H171N-AMP.FUM) complexes have been determined to 2.0, 1.85, and 2.0 A resolution, respectively. The H171A-ADS and H171N-AMP.FUM structures provide the first detailed picture of the ADL active site, and have enabled the precise identification of substrate binding and putative catalytic residues. Contrary to previous suggestions, the ec-ADL structures implicate S295 and H171 in base and acid catalysis, respectively. Furthermore, structural alignments of ec-ADL with other superfamily members suggest for the first time a large conformational movement of the flexible C3 loop (residues 287-303) in ec-ADL upon substrate binding and catalysis, resulting in its closure over the active site. This loop movement has been observed in other superfamily enzymes, and has been proposed to be essential for catalysis. The ADL catalytic mechanism is re-examined in light of the results presented here. 相似文献
1000.
Seok Hwee Koo Tan Ching Ong Kok Ting Chong Caroline Guat Lay Lee Fook Tim Chew Edmund Jon Deoon Lee 《Biological procedures online》2007,9(1):27-42
We have developed and validated a consolidated bead-based genotyping platform, the Bioplex suspension array for simultaneous
detection of multiple single nucleotide polymorphisms (SNPs) of the ATP-binding cassette transporters. Genetic polymorphisms
have been known to influence therapeutic response and risk of disease pathologies. Genetic screening for therapeutic and diagnostic
applications thus holds great promise in clinical management. The allele-specific primer extension (ASPE) reaction was used
to assay 22 multiplexed SNPs for eight subjects. Comparison of the microsphere-based ASPE assay results to sequencing results
showed complete concordance in genotype assignments. The Bioplex suspension array thus proves to be a reliable, cost-effective
and high-throughput technological platform for genotyping. It can be easily adapted to customized SNP panels for specific
applications involving large-scale mutation screening of clinically relevant markers. 相似文献