全文获取类型
收费全文 | 16802篇 |
免费 | 1062篇 |
国内免费 | 32篇 |
学科分类
工业技术 | 17896篇 |
出版年
2023年 | 155篇 |
2022年 | 149篇 |
2021年 | 590篇 |
2020年 | 404篇 |
2019年 | 430篇 |
2018年 | 539篇 |
2017年 | 511篇 |
2016年 | 589篇 |
2015年 | 507篇 |
2014年 | 670篇 |
2013年 | 1174篇 |
2012年 | 1058篇 |
2011年 | 1252篇 |
2010年 | 877篇 |
2009年 | 821篇 |
2008年 | 879篇 |
2007年 | 851篇 |
2006年 | 642篇 |
2005年 | 550篇 |
2004年 | 423篇 |
2003年 | 425篇 |
2002年 | 374篇 |
2001年 | 256篇 |
2000年 | 220篇 |
1999年 | 234篇 |
1998年 | 337篇 |
1997年 | 258篇 |
1996年 | 225篇 |
1995年 | 202篇 |
1994年 | 182篇 |
1993年 | 178篇 |
1992年 | 133篇 |
1991年 | 81篇 |
1990年 | 127篇 |
1989年 | 129篇 |
1988年 | 91篇 |
1987年 | 98篇 |
1986年 | 103篇 |
1985年 | 107篇 |
1984年 | 95篇 |
1983年 | 79篇 |
1982年 | 96篇 |
1981年 | 91篇 |
1980年 | 74篇 |
1979年 | 74篇 |
1978年 | 67篇 |
1977年 | 79篇 |
1976年 | 79篇 |
1975年 | 45篇 |
1974年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
12.
Jakub Drzmisek Daniel Stipl Denisa Petrackova Branislav Vecerek Ana Dienstbier 《International journal of molecular sciences》2021,22(2)
Bacterial pathogens sense specific cues associated with different host niches and integrate these signals to appropriately adjust the global gene expression. Bordetella pertussis is a Gram-negative, strictly human pathogen of the respiratory tract and the etiological agent of whooping cough (pertussis). Though B. pertussis does not cause invasive infections, previous results indicated that this reemerging pathogen responds to blood exposure. Here, omics RNA-seq and LC–MS/MS techniques were applied to determine the blood-responsive regulon of B. pertussis. These analyses revealed that direct contact with blood rewired global gene expression profiles in B. pertussis as the expression of almost 20% of all genes was significantly modulated. However, upon loss of contact with blood, the majority of blood-specific effects vanished, with the exception of several genes encoding the T3SS-secreted substrates. For the first time, the T3SS regulator BtrA was identified in culture supernatants of B. pertussis. Furthermore, proteomic analysis identified BP2259 protein as a novel secreted T3SS substrate, which is required for T3SS functionality. Collectively, presented data indicate that contact with blood represents an important cue for B. pertussis cells. 相似文献
13.
Alexandra Kodadová Zuzana Vitková Petra Herdová Anton Ťažký Jarmila Oremusová Daniel Grančai 《Drug development and industrial pharmacy》2015,41(7):1080-1088
This study deals with the formulation of natural drugs into hydrogels. For the first time, compounds from the sage essential oil were formulated into chitosan hydrogels. A sample preparation procedure for hydrophobic volatile analytes present in a hydrophilic water matrix along with an analytical method based on the gas chromatography coupled with the mass spectrometry (GC-MS) was developed and applied for the evaluation of the identity and quantity of essential oil components in the hydrogels and saline samples. The experimental results revealed that the chitosan hydrogels are suitable for the formulation of sage essential oil. The monoterpene release can be effectively controlled by both chitosan and caffeine concentration in the hydrogels. Permeation experiment, based on a hydrogel with the optimized composition [3.5% (w/w) sage essential oil, 2.0% (w/w) caffeine, 2.5% (w/w) chitosan and 0.1% (w/w) Tween-80] in donor compartment, saline solution in acceptor compartment, and semi-permeable cellophane membrane, demonstrated the useful permeation selectivity. Here, (according to lipophilicity) an enhanced permeation of the bicyclic monoterpenes with antiflogistic and antiseptic properties (eucalyptol, camphor and borneol) and, at the same time, suppressed permeation of toxic thujone (not exceeding its permitted applicable concentration) was observed. These properties highlight the pharmaceutical importance of the developed chitosan hydrogel formulating sage essential oil in the dermal applications. 相似文献
14.
15.
Gehrig Daniel Rebecq Henri Gallego Guillermo Scaramuzza Davide 《International Journal of Computer Vision》2020,128(3):619-619
International Journal of Computer Vision - The original version of this article was unfortunately omitted to publish the footnote “The best result per row is highlighted in bold” in... 相似文献
16.
17.
Daniel T. Payne Mandeep K. Chahal V clav B&rcaron ezina Whitney A. Webre Katsuhiko Ariga Francis D Souza Jan Labuta Jonathan P. Hill 《Frontiers of Chemical Science and Engineering》2020,14(1):28
Chiral 1,1’-binaphthyl-linked diporphyrin ‘tweezers’ (R)-1/(S)-1 and the corresponding zinc(II) complexes (R)-2/(S)-2 were prepared as chiral host molecules, and their utility for chiral analyses (especially enantiomeric excess (ee) determinations) were evaluated. Tris(1-n-dodecyl)porphyrins were used for the first time as the interacting units. Host capabilities of the diporphyrin tweezers were investigated by titrations with (R,R)- and (S,S)-cyclohexane-1,2-diamine (CHDA). The host molecules could be used as multichannel probes of ee by using UV-vis, circular dichroism (CD), fluorescence emission and 1H nuclear magnetic resonance (1H-NMR) methods. Chiral configurations could also be differentiated using CD or 1H-NMR spectroscopy. All three optical techniques give good resolution of ee with reasonable sensitivity considering the low concentrations used (ca. 10−6 mol·L−1). The ee determination of CHDA enantiomers using NMR spectroscopy is also possible because of the reasonably well separated resonances in the case of (R,R)- and (S,S)-CHDA. Non-metallated (R)-1/(S)-1 hosts could not be used to detect chiral information in a strongly acidic chiral guest. This work demonstrates the utility of 1,1’-binapthyl-linked chiral hosts for chiral analysis of ditopically interacting enantiomers. 相似文献
18.
19.
20.