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91.
The Saccharomyces cerevisiae TIF3 gene encodes a 436-amino acid (aa) protein that is the yeast homologue of mammalian translation Initiation factor eIF4B. Tif3p can be divided into three parts, the N-terminal region with an RNA recognition motif (RRM) (aa 1-182), followed in the middle part by a sevenfold repeat of 26 amino acids rich in basic and acidic residues (as 183-350), and a C-terminal region without homology to any known sequence (aa 351-436). We have analyzed several Tif3 proteins with deletions at their N and C termini for their ability (1) to complement a tif3delta strain in vivo, (2) to stimulate Tif3-dependent translation extracts, (3) to bind to single-stranded RNA, and (4) to catalyze RNA strand-exchange in vitro. Here we report that yeast Tif3/eIF4B contains at least two RNA binding domains able to bind to single-stranded RNA. One is located in the N-terminal region of the protein carrying the RRM, the other in the C-terminal two-thirds region of Tif3p. The RRM-containing domain and three of the seven repeat motifs are essential for RNA strand-exchange activity of Tif3p and translation in vitro and for complementation of a tif3delta strain, suggesting an important role for RNA strand-exchange activity in translation. 相似文献
92.
93.
H. G. Haldenwanger H.-H. Braess P. Mast S. Schper D. Wagner O. Altmann P. Jeschonnek J. Korinth A. Balk G. Kunstmann M. B. Hegebolz R. Krieger G. Walter F. Woite K. Fraunhofer W. Kraus G. Watzek H. Nonner M. Seifert W. Schweiger G. Paller 《Materialwissenschaft und Werkstofftechnik》1991,22(7):275-278
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95.
Porous graphitic carbon (PGC) emerges as an ideal stationary phase for LC-ESI-MS of complex oligosaccharides. Therefore, we studied the factors influencing detection and elution of charged oligosaccharides from PGC columns coupled to an ESI source. Electrosorption by the carbon surface leads to total retention of very acidic glycans on instruments where voltage is applied to the spray needle. This problem can be eliminated by thorough electrical grounding. A point of general importance is the influence of ionic strength on the elution and peak shape of glycans containing several carboxylic acid groups in the form of sialic acids or uronic acids. Solvent pH had a marginal effect on the ionization efficiency in both ion polarities, but the content of organic solvent strongly influenced signal intensity of acidic glycans in the negative mode. As a consequence, detection in the positive ion mode appears preferable when neutral and charged glycans shall be quantitated in the same sample. While retention of neutral glycans is not affected by pH, sialylated species are retained somewhat stronger at acidic pH resulting in a larger spread of the entire elution range of N-glycans. Remarkably, retention of glycans on PGC increased at higher temperatures. 相似文献
96.
Altmann D Schaar H Bartel C Schorkopf DL Miller I Kreuzinger N Möstl E Grillitsch B 《Water research》2012,46(11):3693-3702
Tertiary wastewater treatment plant effluent before and after ozonation (0.6-1.1 g O3/g DOC) was tested for aquatic ecotoxicity in a battery of standardised microbioassays with green algae, daphnids, and zebrafish eggs. In addition, unconjugated estrogen and 17β-hydroxyandrogen immunoreactive substances were quantified by means of enzyme immunoassays, and endocrine effects were analysed in a 21-day fish screening assay with adult male and female medaka (Oryzias latipes). Ozonation decreased estrogen-immunoreactivity by 97.7 ± 1.2% and, to a lesser extent, androgen-immunoreactivity by 56.3 ± 16.5%. None of the short-term exposure ecotoxicity tests revealed any adverse effects of the tertiary effluent, neither before nor after the ozonation step. Similarly in the fish screening assay, reproductive fitness parameters showed no effects attributed to micropollutants, and no detrimental effects of the effluents were observed. Based on the presented screening, ozonation effectively reduced steroid hormone levels in the wastewater treatment plant effluent without increasing the effluent's ecotoxicity. 相似文献
97.
Ioannis Spanos César Pelegrín Rellán Lena Altmann Marcus Bäumer Matthias Arenz 《International Journal of Hydrogen Energy》2014
In the presented work we investigate the influence of de-alloying carbon supported PtxCo1−x alloy nanoparticles (NPs) on their oxygen reduction reaction (ORR) activity. In our study we used a modification of a recently developed colloidal synthesis approach in order to prepare NPs of similar size, i.e. around 2 nm in diameter, but varying initial Pt:Co ratios. The results show that using a surfactant is favorable to control the initial Pt:Co ratio. The initial composition of the catalyst however is lost upon introduction into an acid environment, i.e. the well-known effect of chemical de-alloying occurs. Interestingly, despite the fact that due to de-alloying almost all Co is removed from the PtxCo1−x NPs, a clear trend of increasing ORR activity with increasing initial Co content is observed. The results indicate that the process of chemical de-alloying is favorable for producing active ORR catalysts. 相似文献
98.
Emre Başeski Nicolas Pugeault Sinan Kalkan Leon Bodenhagen Justus H. Piater Norbert Krüger 《Journal of Visual Communication and Image Representation》2010,21(8):850-864
In this work, we make use of 3D contours and relations between them (namely, coplanarity, cocolority, distance and angle) for four different applications in the area of computer vision and vision-based robotics. Our multi-modal contour representation covers both geometric and appearance information. We show the potential of reasoning with global entities in the context of visual scene analysis for driver assistance, depth prediction, robotic grasping and grasp learning. We argue that, such 3D global reasoning processes complement widely-used 2D local approaches such as bag-of-features since 3D relations are invariant under camera transformations and 3D information can be directly linked to actions. We therefore stress the necessity of including both global and local features with different spatial dimensions within a representation. We also discuss the importance of an efficient use of the uncertainty associated with the features, relations, and their applicability in a given context. 相似文献
99.
Pabst M Grass J Fischl R Léonard R Jin C Hinterkörner G Borth N Altmann F 《Analytical chemistry》2010,82(23):9782-9788
We examined the analysis of nucleotides and nucleotide sugars by chromatography on porous graphitic carbon with mass spectrometric detection, a method that evades contamination of the MS instrument with ion pairing reagent. At first, adenosine triphosphate (ATP) and other triphosphate nucleotides exhibited very poor chromatographic behavior on new columns and could hardly be eluted from columns previously cleaned with trifluoroacetic acid. Satisfactory performance of both new and older columns could, however, be achieved by treatment with reducing agent and, unexpectedly, hydrochloric acid. Over 40 nucleotides could be detected in cell extracts including many isobaric compounds such as ATP, deoxyguanosine diphosphate (dGTP), and phospho-adenosine-5'-phosphosulfate or 3',5'-cyclic adenosine 5'-monophosphate (AMP) and its much more abundant isomer 2',3'-cyclic AMP. A fast sample preparation procedure based on solid-phase extraction on carbon allowed detection of very short-lived analytes such as cytidine 5'-monophosphate (CMP)-2-keto-deoxy-octulosonic acid. In animal cells and plant tissues, about 35 nucleotide sugars were detected, among them rarely considered metabolites such as uridine 5'-diphosphate (UDP)-l-arabinopyranose, UDP-L-arabinofuranose, guanosine 5'-diphosphate (GDP)-L-galactofuranose, UDP-L-rhamnose, and adenosine diphosphate (ADP)-sugars. Surprisingly, UDP-arabinopyranose was also found in Chinese hamster ovary (CHO) cells. Due to the unique structural selectivity of graphitic carbon, the method described herein distinguishes more nucleotides and nucleotide sugars than previously reported approaches. 相似文献
100.
Routine human behavior has often been attributed to plans—mental representations of sequences goals and actions—but can also be attributed to more opportunistic interactions of mind and a structured environment. This study asks whether performance on a task traditionally analyzed in terms of plans can be better understood from a “situated” (or “embodied”) perspective. A saccade-contingent display-updating paradigm is used to change the environment by adding, deleting, and moving task-relevant objects without participants’ direct awareness. Response latencies, action patterns, and eye movements all indicate that performance is guided not by plans stored in memory but by a control routine bound to objects as needed by perception and selective attention. The results have implications for interpreting everyday task performance and particular neuropsychological deficits. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献