全文获取类型
收费全文 | 1092篇 |
免费 | 30篇 |
国内免费 | 3篇 |
专业分类
化学 | 723篇 |
晶体学 | 2篇 |
力学 | 10篇 |
数学 | 262篇 |
物理学 | 128篇 |
出版年
2023年 | 6篇 |
2021年 | 17篇 |
2020年 | 13篇 |
2019年 | 17篇 |
2018年 | 6篇 |
2017年 | 15篇 |
2016年 | 23篇 |
2015年 | 20篇 |
2014年 | 24篇 |
2013年 | 32篇 |
2012年 | 52篇 |
2011年 | 40篇 |
2010年 | 31篇 |
2009年 | 24篇 |
2008年 | 36篇 |
2007年 | 41篇 |
2006年 | 43篇 |
2005年 | 33篇 |
2004年 | 28篇 |
2003年 | 16篇 |
2002年 | 11篇 |
1997年 | 13篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 19篇 |
1993年 | 16篇 |
1992年 | 22篇 |
1991年 | 21篇 |
1990年 | 22篇 |
1989年 | 28篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 19篇 |
1980年 | 16篇 |
1979年 | 24篇 |
1978年 | 18篇 |
1977年 | 21篇 |
1976年 | 19篇 |
1975年 | 16篇 |
1974年 | 13篇 |
1973年 | 12篇 |
1970年 | 8篇 |
1900年 | 8篇 |
1893年 | 6篇 |
1892年 | 7篇 |
排序方式: 共有1125条查询结果,搜索用时 194 毫秒
1.
Mnich Konrad Lazarek Mateusz Stefanski Andrzej Perlikowski Przemyslaw 《Meccanica》2022,57(8):1955-1973
Meccanica - This paper presents the experimental identification of the friction force in the inerter with constant and variable inertance. The change of intertance is possible due to the... 相似文献
2.
3.
Kamila Rybczyska-Tkaczyk Teresa Korniowicz-Kowalska Konrad A. Szychowski 《Molecules (Basel, Switzerland)》2021,26(2)
The aim of this study was to evaluate the bioremoval mechanism of anthracycline antibiotics by the white-rot fungus B. adusta CCBAS 930. The activity of oxidoreductases and levels of phenolic compounds and free radicals were determined during the biotransformation of anthraquinone antibiotics: daunomycin (DNR) and doxorubicin (DOX) by B. adusta strain CCBAS 930. Moreover, phytotoxicity (Lepidium sativum L.), ecotoxicity (Vibrio fischeri), genotoxicity and cytotoxicity of anthraquinone dyes were evaluated before and after biological treatment. More than 80% and 90% of DNR and DOX were removed by biodegradation (decolorization). Initial solutions of DNR and DOX were characterized by eco-, phyto-, geno- and cytotoxicity. Despite efficient decolorization, secondary metabolites, toxic to bacteria, formed during biotransformation of anthracycline antibiotics in B. adusta CCBAS 930 cultures. DNR and DOX metabolites did not increase reactive oxygen species (ROS) production in human fibroblasts and resazurin reduction. DNR metabolites did not change caspase-3 activity. 相似文献
4.
Ursula M Kotyrba Kevin Pr?pper Eike-F Sachs Anastasiya Myanovska Tobias Joppe Friederike Lissy George M Sheldrick Konrad Koszinowski Ulf Diederichsen 《ChemistryOpen》2014,3(4):152-160
The DNA bisintercalator triostin A is structurally based on a disulfide-bridged depsipeptide scaffold that provides preorganization of two quinoxaline units in 10.5 Å distance. Triostin A analogues are synthesized with nucleobase recognition units replacing the quinoxalines and containing two additional recognition units in between. Thus, four nucleobase recognition units are organized on a rigid template, well suited for DNA double strand interactions. The new tetra-nucleobase binders are synthesized as aza-TANDEM derivatives lacking the N-methylation of triostin A and based on a cyclopeptide backbone. Synthesis of two tetra-nucleobase aza-TANDEM derivatives is established, DNA interaction analyzed by microscale thermophoresis, cytotoxic activity studied and a nucleobase sequence dependent self-aggregation investigated by mass spectrometry. 相似文献
5.
Charl Ras Konrad Swanepoel Doreen Anne Thomas 《Journal of Optimization Theory and Applications》2017,172(3):845-873
An approximate Steiner tree is a Steiner tree on a given set of terminals in Euclidean space such that the angles at the Steiner points are within a specified error from \(120^{\circ }\). This notion arises in numerical approximations of minimum Steiner trees. We investigate the worst-case relative error of the length of an approximate Steiner tree compared to the shortest tree with the same topology. It has been conjectured that this relative error is at most linear in the maximum error at the angles, independent of the number of terminals. We verify this conjecture for the two-dimensional case as long as the maximum angle error is sufficiently small in terms of the number of terminals. In the two-dimensional case we derive a lower bound for the relative error in length. This bound is linear in terms of the maximum angle error when the angle error is sufficiently small in terms of the number of terminals. We find improved estimates of the relative error in length for larger values of the maximum angle error and calculate exact values in the plane for three and four terminals. 相似文献
6.
Dr. Konrad Viehrig Dr. Frank Surup Dr. Carsten Volz Dr. Jennifer Herrmann Dr. Antoine Abou Fayad Sebastian Adam Dr. Jesko Köhnke Prof. Dr. Dirk Trauner Prof. Dr. Rolf Müller 《Angewandte Chemie (International ed. in English)》2017,56(26):7407-7410
Secondary metabolome mining efforts in the myxobacterial multiproducer of natural products, Chondromyces crocatus Cm c5, resulted in the isolation and structure elucidation of crocagins, which are novel polycyclic peptides containing a tetrahydropyrrolo[2,3-b]indole core. The gene cluster was identified through an approach combining genome analysis, targeted gene inactivation in the producer, and in vitro experiments. Based on our findings, we developed a biosynthetic scheme for crocagin biosynthesis. These natural products are formed from the three C-terminal amino acids of a precursor peptide and thus belong to a novel class of ribosomally synthesized and post-translationally modified peptides (RiPPs). We demonstrate that crocagin A binds to the carbon storage regulator protein CsrA, thereby inhibiting the ability of CsrA to bind to its cognate RNA target. 相似文献
7.
Jan Leipert Philipp T. Kaulich Max K. Steinbach Britta Steer Konrad Winkels Christine Blurton Dr. Matthias Leippe Dr. Andreas Tholey 《Angewandte Chemie (International ed. in English)》2023,62(28):e202301969
While most nanoproteomics approaches for the analysis of low-input samples are based on bottom-up proteomics workflows, top-down approaches enabling proteoform characterization are still underrepresented. Using mammalian cell proteomes, we established a facile one-pot sample preparation protocol based on protein aggregation on magnetic beads and intact proteoform elution using 40 % formic acid. Performed on a digital microfluidics device, the workflow enabled sensitive analyses of single Caenorhabditis elegans nematodes, thereby increasing the number of proteoform identifications compared to in-tube sample preparation by 46 %. Label-free quantification of single nematodes grown under different conditions allowed to identify changes in the abundance of proteoforms not distinguishable by bottom-up proteomics. The presented workflow will facilitate proteoform-directed analysis on samples of limited availability. 相似文献
8.
Dr. Mostofa K. Khan Anas Bsoul Prof. Konrad Walus Dr. Wadood Y. Hamad Prof. Mark J. MacLachlan 《Angewandte Chemie (International ed. in English)》2015,54(14):4304-4308
Chiral nematic mesoporous phenol‐formaldehyde resins, which were prepared using cellulose nanocrystals as a template, can be used as a substrate to produce latent photonic images. These resins undergo swelling, which changes their reflected color. By writing on the films with chemical inks, the density of methylol groups in the resin changes, subsequently affecting their degree of swelling and, consequently, their color. Writing on the films gives latent images that are revealed only upon swelling of the films. Using inkjet printing, it is possible to make higher resolution photonic patterns both as text and images that can be visualized by swelling and erased by drying. This novel approach to printing photonic patterns in resin films may be applied to anti‐counterfeit tags, signage, and decorative applications. 相似文献
9.
The vibration method represents a practical method for the measurement of adhesion forces and adhesion force distributions. This method causes sinusoidally altemating stresses and yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an adhesion force intensification through flattening of asperities. The measuring principle of the vibration method and the analysis of experimental results are described in the article. Normal adhesion forces (pull-off forces) are measured using the vibration method and the colloidal probe technique. The results of both methods show good agreement for small particle sizes. The influence of the detachment force direction is shown by comparing tangential and normal adhesion forces measured using particle reentrainment in a turbulent air flow and the vibration method, respectively. The surface roughness of the substrate and the relative humidity are shown to significantly influence the measured adhesion forces. For the calculation of the adhesion forces, an approach by Rabinovich was combined with approximations of plastic micro asperity flattening. The Rabinovich approach accounts for roughness effects on the van der Waals force by incorporating the rms roughness of the interacting surfaces. rms-values of the particles and substrates were measured with atomic force microscopy at different scanning areas. 相似文献
10.