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131.
The Helicobacter pylori VacA cytotoxin activates RBL-2H3 cells by inducing cytosolic calcium oscillations 总被引:2,自引:0,他引:2
de Bernard M Cappon A Pancotto L Ruggiero P Rivera J Del Giudice G Montecucco C 《Cellular microbiology》2005,7(2):191-198
Helicobacter pylori causes an acute inflammatory response followed by chronic infection of the human gastric mucosa. Identification of the bacterial molecules endowed with a pro-inflammatory activity is essential to a molecular understanding of the pathogenesis of H. pylori associated diseases. The vacuolating cytotoxin A (VacA) induces mast cells to release pro-inflammatory cytokines. Here, we show that VacA activates the mast cell line RBL-2H3 by rapidly inducing an oscillation of the level of cytosolic calcium with exocytosis of secretory granules. Cytosolic calcium derives mainly from intracellular stores. VacA also stimulates a calcium-dependent production of pro-inflammatory cytokines, including tumour necrosis factor alpha (TNF-alpha). These observations indicate that VacA may act as a pro-inflammatory factor of H. pylori at very early stages of the innate immune response. 相似文献
132.
Naccobus aberrans is a major pest of the potato crop in the Andean regions of Argentina, Bolivia, and Perú. It is endemic in northwest Argentina and is also found in lowlands. The resistance of eleven Andean potato landraces and three accessions of the wild tuber-bearing species Solanum acaule, S. infundibuliforme, and S. megistacrolobum were evaluated against a population of N. aberrans from Coctaca, Jujuy province, while Solanum tuberosum ssp. tuberosum 'Spunta', 'Kennebec', and 'Frital INTA' were evaluated against a population from the southeast of Buenos Aires province. The presence, the number of galls, and the number of individuals were recorded. In addition, a reproduction factor was calculated and races were determined. Results showed that the N. aberrans population from Coctaca corresponded to race 2 and the population from the lowlands belonged to the sugar beet group. Landrace Azul, one genotype of S. megistacrolobum, and two genotypes of S. acaule showed resistance towards the race from Coctaca while no infection was recorded in potato cultivars with the Naccobus race from the lowland area. 相似文献
133.
May T Mueller PP Weich H Froese N Deutsch U Wirth D Kröger A Hauser H 《Journal of biotechnology》2005,120(1):99-110
Mouse cell lines were immortalized by introduction of specific immortalizing genes. Embryonic and adult animals and an embryonal stem cell line were used as a source of primary cells. The immortalizing genes were either introduced by DNA transfection or by ecotropic retrovirus transduction. Fibroblasts were obtained by expression of SV40 virus large T antigen (TAg). The properties of the resulting fibroblast cell lines were reproducible, independent of the donor mouse strains employed and the cells showed no transformed properties in vitro and did not form tumors in vivo. Endothelial cell lines were generated by Polyoma virus middle T antigen expression in primary embryonal cells. These cell lines consistently expressed relevant endothelial cell surface markers. Since the expression of the immortalizing genes was expected to strongly influence the cellular characteristics fibroblastoid cells were reversibly immortalized by using a vector that allows conditional expression of the TAg. Under inducing conditions, these cells exhibited properties that were highly similar to the properties of constitutively immortalized cells. In the absence of TAg expression, cell proliferation stops. Cell growth is resumed when TAg expression is restored. Gene expression profiling indicates that TAg influences the expression levels of more than 1000 genes that are involved in diverse cellular processes. The data show that conditionally immortalized cell lines have several advantageous properties over constitutively immortalized cells. 相似文献
134.
Brzuszkiewicz E Thürmer A Schuldes J Leimbach A Liesegang H Meyer FD Boelter J Petersen H Gottschalk G Daniel R 《Archives of microbiology》2011,193(12):883-891
The genome sequences of two Escherichia coli O104:H4 strains derived from two different patients of the 2011 German E. coli outbreak were determined. The two analyzed strains were designated E. coli GOS1 and GOS2 (German outbreak strain). Both isolates comprise one chromosome of approximately 5.31 Mbp and two putative plasmids. Comparisons of the 5,217
(GOS1) and 5,224 (GOS2) predicted protein-encoding genes with various E. coli strains, and a multilocus sequence typing analysis revealed that the isolates were most similar to the entero-aggregative
E. coli (EAEC) strain 55989. In addition, one of the putative plasmids of the outbreak strain is similar to pAA-type plasmids of
EAEC strains, which contain aggregative adhesion fimbrial operons. The second putative plasmid harbors genes for extended-spectrum
β-lactamases. This type of plasmid is widely distributed in pathogenic E. coli strains. A significant difference of the E. coli GOS1 and GOS2 genomes to those of EAEC strains is the presence of a prophage encoding the Shiga toxin, which is characteristic
for enterohemorrhagic E. coli (EHEC) strains. The unique combination of genomic features of the German outbreak strain, containing characteristics from
pathotypes EAEC and EHEC, suggested that it represents a new pathotype Entero-Aggregative-Haemorrhagic E
scherichia
c
oli (EAHEC). 相似文献
135.
Andreas Katsiaras Anne B Newman Andrea Kriska Jennifer Brach Shanthi Krishnaswami Eleanor Feingold Stephen B Kritchevsky Rongling Li Tamara B Harris Ann Schwartz Bret H Goodpaster 《Journal of applied physiology》2005,99(1):210-216
We examined the muscle fatigue characteristics in older men and women and determined whether these were related to the size, strength, or quality of muscle. A total of 1,512 men and women aged 70-79 yr from the Health, Aging, and Body Composition Study participated in this study. Muscle cross-sectional area and attenuation were determined with computed tomography. Skeletal muscle fatigue and strength (peak torque) of the knee extensors and flexors were measured using isokinetic dynamometry. Men were more fatigue resistant than women for both knee extension (fatigue index: 70.4 +/- 15.3 vs. 66.9 +/- 14.3%; P < 0.05) and knee flexion (67.9 +/- 16.4 vs. 64.9 +/- 17.6%; P < 0.05). Peak torque and muscle quality (specific torque) were higher in men than women for knee extension (99.6 +/- 28.2 vs. 63.0 +/- 16.8 N x m and 1.62 +/- 0.43 vs. 1.51 +/- 0.39 N x m/cm2; both P < 0.05) and for knee flexion (74.0 +/- 26.4 vs. 49.6 +/- 15.9 N x m and 2.47 +/- 1.29 vs. 2.22 +/- 0.78 N x m/cm2; both P < 0.05). Total work and power output was greater in men compared with women for both the quadriceps (1,353 +/- 451 vs. 832 +/- 264 J and 87.7 +/- 33.5 vs. 53.3 +/- 19.2 W; both P < 0.05) and the hamstrings (741 +/- 244 vs. 510 +/- 141 J and 35.4 +/- 16.0 vs. 23.7 +/- 10.2 W; both P < 0.05). In both genders, the quadriceps was able to perform more work with greater power compared with the hamstrings. Those who were stronger actually had greater fatigue after adjusting for age, race, physical activity, and total body fat. In conclusion, older men were more fatigue resistant than women, although in both men and women greater fatigue was not related to muscle weakness. 相似文献
136.
Andrea Schmidt Stephanie Bringer-Meyer Karl Poralla Hermann Sahm 《Applied microbiology and biotechnology》1989,30(2):170-175
Summary The influence of different primary aliphatic alcohols on the activities of two key enzymes in hopanoid biosynthesis of Zymomonas mobilis was investigated. By use of 14C- and 3H-labelled substrates the enzymes 3-hydroxy-3-methylglutaryl-CoA-reductase and squalene-hopenecyclase were detected with activities of 1.6 pmol x (min x mg protein)-1 and 2.3 pmol x- (min x mg protein)-1, respectively. Cells grown in the presence of 6% (v/v) ethanol did not show higher activities of these enzymes than cells grown in the presence of 1% (v/v) ethanol. Furthermore, 3-hydroxy-3-methylglutaryl-CoA-reductase was not activated by ethanol. However, ethanol activated the squalene-hopene-cyclase when added to the enzyme test system. Besides ethanol, propanol also had a positive effect on the squalene-hopene-cyclase: the enzyme's activity increased 1.7-fold in the presence of either alcohol at a concentration of 6% (v/v). This corresponded with a similar increase of hopanoid content of whole cells when grown in the presence of 6% (v/v) added ethanol or propanol. These results indicated that the squalene-hopene-cyclase has a regulatory function in the alcohol dependent hopanoid biosynthesis of Z. mobilis.Abbreviation HMG-CoA-reductase
3-hydroxy-3-methylglutaryl-coenzyme A-reductase 相似文献
137.
Luciano A Marraffini Andrea C Dedent Olaf Schneewind 《Microbiology and molecular biology reviews》2006,70(1):192-221
The cell wall envelopes of gram-positive bacteria represent a surface organelle that not only functions as a cytoskeletal element but also promotes interactions between bacteria and their environment. Cell wall peptidoglycan is covalently and noncovalently decorated with teichoic acids, polysaccharides, and proteins. The sum of these molecular decorations provides bacterial envelopes with species- and strain-specific properties that are ultimately responsible for bacterial virulence, interactions with host immune systems, and the development of disease symptoms or successful outcomes of infections. Surface proteins typically carry two topogenic sequences, i.e., N-terminal signal peptides and C-terminal sorting signals. Sortases catalyze a transpeptidation reaction by first cleaving a surface protein substrate at the cell wall sorting signal. The resulting acyl enzyme intermediates between sortases and their substrates are then resolved by the nucleophilic attack of amino groups, typically provided by the cell wall cross bridges of peptidoglycan precursors. The surface protein linked to peptidoglycan is then incorporated into the envelope and displayed on the microbial surface. This review focuses on the mechanisms of surface protein anchoring to the cell wall envelope by sortases and the role that these enzymes play in bacterial physiology and pathogenesis. 相似文献
138.
Varga A Flachner B Konarev P Gráczer E Szabó J Svergun D Závodszky P Vas M 《FEBS letters》2006,580(11):2698-2706
Closure of the two domains of 3-phosphoglycerate kinase, upon substrate binding, is essential for the enzyme function. The available crystal structures cannot provide sufficient information about the mechanism of substrate assisted domain closure and about the requirement of only one or both substrates, since lattice forces may hinder the large scale domain movements. In this study the known X-ray data, obtained for the open and closed conformations, were probed by solution small-angle X-ray scattering experiments. The results prove that binding of both substrates is essential for domain closure. Molecular graphical analysis, indeed, reveals formation of a double-sided H-bond network, which affects substantially the shape of the main molecular hinge at beta-strand L, under the concerted action of both substrates. 相似文献
139.
Although pollen tube growth is essential for plant fertilization and reproductive success, the regulators of the actin-related growth machinery and the cytosolic Ca2+ gradient thought to determine how these cells elongate remain poorly defined. Phospholipases, their substrates, and their phospholipid turnover products have been proposed as such regulators; however, the relevant phospholipase(s) have not been characterized. Therefore, we cloned cDNA for a pollen-expressed phosphatidylinositol 4,5-bisphosphate (PtdInsP2)-cleaving phospholipase C (PLC) from Petunia inflata, named Pet PLC1. Expressing a catalytically inactive form of Pet PLC1 in pollen tubes caused expansion of the apical Ca2+ gradient, disruption of the organization of the actin cytoskeleton, and delocalization of growth at the tube tip. These phenotypes were suppressed by depolymerizing actin with low concentrations of latrunculin B, suggesting that a critical site of action of Pet PLC1 is in regulating actin structure at the growing tip. A green fluorescent protein (GFP) fusion to Pet PLC1 caused enrichment in regions of the apical plasma membrane not undergoing rapid expansion, whereas a GFP fusion to the PtdInsP2 binding domain of mammalian PLC delta1 caused enrichment in apical regions depleted in PLC. Thus, Pet PLC1 appears to be involved in the machinery that restricts growth to the very apex of the elongating pollen tube, likely through its regulatory action on PtdInsP2 distribution within the cell. 相似文献
140.
The steadily increasing availability of human embryonic stem (hES) cell lines has created strong interest in applying available tools for gene transfer in murine cells to human systems. Here we present a method for the transduction of hES cells with ecotropic retroviral vectors. hES cells were transiently transfected with a construct carrying the murine retrovirus receptor mCAT1. Subsequently, the cells were exposed to replication-deficient Moloney murine leukemia virus (MoMuLV) derivatives or pseudotyped lentiviral vectors. With oncoretroviral vectors, this procedure yields overall transduction efficiencies of up to 20% and permits selection of permanently transduced clones with high frequency. Selected clones maintained expression of pluripotency-associated markers and exhibited multi-germ layer differentiation both in vitro and in vivo. HES cell-derived somatic cells including neural progeny maintained high levels of transgene expression. Lentiviral vectors pseudotyped with the MoMuLV envelope could be introduced in the same manner with efficiencies of up to 33%. Transgene expression of lentivirally transduced hES cells remained permanent after differentiation even without selection pressure. Bypassing the regulatory issues associated with the use of amphotropic retroviral systems and exploiting the large pool of existing murine vectors, this method provides a safe and versatile tool for gene transfer and lineage analysis in hES cells and their progeny. 相似文献