全文获取类型
收费全文 | 4891篇 |
免费 | 213篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 73篇 |
综合类 | 8篇 |
化学工业 | 997篇 |
金属工艺 | 168篇 |
机械仪表 | 99篇 |
建筑科学 | 224篇 |
矿业工程 | 18篇 |
能源动力 | 111篇 |
轻工业 | 561篇 |
水利工程 | 37篇 |
石油天然气 | 8篇 |
无线电 | 341篇 |
一般工业技术 | 884篇 |
冶金工业 | 898篇 |
原子能技术 | 39篇 |
自动化技术 | 651篇 |
出版年
2023年 | 38篇 |
2022年 | 34篇 |
2021年 | 72篇 |
2020年 | 63篇 |
2019年 | 45篇 |
2018年 | 104篇 |
2017年 | 121篇 |
2016年 | 120篇 |
2015年 | 119篇 |
2014年 | 158篇 |
2013年 | 242篇 |
2012年 | 250篇 |
2011年 | 267篇 |
2010年 | 225篇 |
2009年 | 205篇 |
2008年 | 224篇 |
2007年 | 196篇 |
2006年 | 149篇 |
2005年 | 151篇 |
2004年 | 131篇 |
2003年 | 110篇 |
2002年 | 127篇 |
2001年 | 88篇 |
2000年 | 103篇 |
1999年 | 80篇 |
1998年 | 258篇 |
1997年 | 183篇 |
1996年 | 104篇 |
1995年 | 102篇 |
1994年 | 83篇 |
1993年 | 83篇 |
1992年 | 48篇 |
1991年 | 46篇 |
1990年 | 47篇 |
1989年 | 43篇 |
1988年 | 46篇 |
1987年 | 42篇 |
1986年 | 35篇 |
1985年 | 36篇 |
1984年 | 43篇 |
1983年 | 41篇 |
1982年 | 30篇 |
1981年 | 35篇 |
1980年 | 42篇 |
1979年 | 26篇 |
1978年 | 24篇 |
1977年 | 29篇 |
1976年 | 64篇 |
1975年 | 34篇 |
1973年 | 19篇 |
排序方式: 共有5117条查询结果,搜索用时 31 毫秒
1.
2.
3.
Pierre Santucci Christina Dedaki Alexandros Athanasoulis Laura Gallorini Anaïs Munoz Dr. Stéphane Canaan Dr. Jean-François Cavalier Dr. Victoria Magrioti 《ChemMedChem》2019,14(3):349-358
In the quest for new antibacterial agents, a series of novel long- and medium-chain mono- and disubstituted β-lactones was developed. Their activity against three pathogenic mycobacteria—M. abscessus, M. marinum, and M. tuberculosis—was assessed by the resazurin microtiter assay (REMA). Among the 16 β-lactones synthesized, only 3-hexadecyloxetan-2-one (VM005) exhibited promising activity against M. abscessus, whereas most of the β-lactones showed interesting activities against M. marinum, similar to that of the classical antibiotic, isoniazid. Regarding M. tuberculosis, six compounds were found to be active against this mycobacterium, with β-lactone VM008 [trans-(Z)-3-(hexadec-7-en-1-yl)-4-propyloxetan-2-one] being the best growth inhibitor. The promising antibacterial activities of the best compounds in this series suggest that these molecules may serve as leads for the development of much more efficient antimycobacterial agents. 相似文献
4.
5.
Dr. Lina Liang Tong-You Wade Wei Pei-Yu Wu Wouter Herrebout Ming-Daw Tsai Prof. Stéphane P. Vincent 《Chembiochem : a European journal of chemical biology》2020,21(20):2982-2990
d -Glycero-d -manno-heptose-1β,7-bisphosphate (HBP) and d -glycero-d -manno-heptose-1β-phosphate (H1P) are bacterial metabolites that were recently shown to stimulate inflammatory responses in host cells through the activation of the TIFA-dependent NF-κB pathway. To better understand structure-based activity in relation to this process, a family of nonhydrolyzable phosphonate analogues of HBP and H1P was synthesized. The inflammation modulation by which these molecules induce the TIFA-NF-κB signal axis was evaluated in vivo at a low-nanomolar concentration (6 nM) and compared to that of the natural metabolites. Our data showed that three phosphonate analogues had similar stimulatory activity to HBP, whereas two phosphonates antagonized HBP-induced TIFA-NF-κB signaling. These results open new horizons for the design of pro-inflammatory and innate immune modulators that could be used as vaccine adjuvant. 相似文献
6.
Jasmin Kuhn Philipp M. Klein Nader Al Danaf Joel Z. Nordin Sren Reinhard Dominik M. Loy Miriam Hhn Samir El Andaloussi Don C. Lamb Ernst Wagner Yoshitsugu Aoki Taavi Lehto Ulrich Lchelt 《Advanced functional materials》2019,29(48)
Phosphorodiamidate morpholino oligomers (PMOs) are oligonucleotide analogs that can be used for therapeutic modulation of pre‐mRNA splicing. Similar to other classes of nucleic acid‐based therapeutics, PMOs require delivery systems for efficient transport to the intracellular target sites. Here, artificial peptides based on the oligo(ethylenamino) acid succinyl‐tetraethylenpentamine (Stp), hydrophobic modifications, and an azide group are presented, which are used for strain‐promoted azide‐alkyne cycloaddition conjugation with splice‐switching PMOs. By systematically varying the lead structure and formulation, it is determined that the type of contained fatty acid and supramolecular assembly have a critical impact on the delivery efficacy. A compound containing linolenic acid with three cis double bonds exhibits the highest splice‐switching activity and significantly increases functional protein expression in pLuc/705 reporter cells in vitro and after local administration in vivo. Structural and mechanistic studies reveal that the lipopeptide PMO conjugates form nanoparticles, which accelerate cellular uptake and that the content of unsaturated fatty acids enhances endosomal escape. In an in vitro Duchenne muscular dystrophy exon skipping model using H2K‐mdx52 dystrophic skeletal myotubes, the highly potent PMO conjugates mediate significant splice‐switching at very low nanomolar concentrations. The presented aminoethylene‐lipopeptides are thus a promising platform for the generation of PMO‐therapeutics with a favorable activity/toxicity profile. 相似文献
7.
Vehicle detection by means of stereo vision-based obstacles features extraction and monocular pattern analysis. 总被引:2,自引:0,他引:2
Gwena?lle Toulminet Massimo Bertozzi Stéphane Mousset Abdelaziz Bensrhair Alberto Broggi 《IEEE transactions on image processing》2006,15(8):2364-2375
This paper presents a stereo vision system for the detection and distance computation of a preceding vehicle. It is divided in two major steps. Initially, a stereo vision-based algorithm is used to extract relevant three-dimensional (3-D) features in the scene, these features are investigated further in order to select the ones that belong to vertical objects only and not to the road or background. These 3-D vertical features are then used as a starting point for preceding vehicle detection; by using a symmetry operator, a match against a simplified model of a rear vehicle's shape is performed using a monocular vision-based approach that allows the identification of a preceding vehicle. In addition, using the 3-D information previously extracted, an accurate distance computation is performed. 相似文献
8.
M Fern? PO Bendahl A Brisfors K Byman M Ekeberg L Ferraud K Grankvist B Hjalmers A Nilsson G Sellberg L Skoog O St?l I Wingmo 《Canadian Metallurgical Quarterly》1997,36(8):793-798
Estrogen and progesterone receptor analysis results were compared within and between six laboratories in Sweden using frozen breast cancer cytosol samples, and the same technique (enzyme immunoassay, Abbott Laboratories). The concordance in receptor status (positive vs. negative) was excellent (98.4% (571/580)). The discordant results were attributable to values near cut-off (n = 4) or outliers (n = 5), the latter probably being due to analytical errors. One laboratory reported significantly higher ER concentrations than the others; thus caution should be observed when comparing absolute values from different centers. For PgR there were similar differences between the laboratories. However, the intra- and inter-laboratory differences were small compared with the overall variability in ER and PgR content between different samples in a large database. The range of the median intra-laboratory coefficient of variation was 11-23% for ER and 12-19% for PgR, indicating that there is room for improvement in the quality of assay performance. 相似文献
9.
Christiane Stüber 《Ethik in der Medizin》2005,17(1):57-60
Ohne Zusammenfassung 相似文献
10.
Pablo Esquinazi Miguel A. Ramos Reinhard König 《Journal of Low Temperature Physics》2004,135(1-2):27-38
We discuss the strain dependence of the acoustic properties of amorphous metals in both normal and superconducting states, in the temperature range 0.1 mK<T<1 K. A crossover is found when the strain energy is of the order of the effective interaction energy between tunneling systems at the corresponding temperature. Our results provide clear evidence for the interaction between tunneling systems, whose energy is in quantitative agreement with theoretical expectations, and reveal that without the knowledge of the corresponding strain dependences, the measured temperature dependences below ~50 mK of the acoustic properties of disordered solids are rather meaningless. 相似文献