全文获取类型
收费全文 | 5754篇 |
免费 | 263篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 53篇 |
综合类 | 23篇 |
化学工业 | 1128篇 |
金属工艺 | 90篇 |
机械仪表 | 125篇 |
建筑科学 | 297篇 |
矿业工程 | 10篇 |
能源动力 | 226篇 |
轻工业 | 356篇 |
水利工程 | 56篇 |
石油天然气 | 31篇 |
无线电 | 513篇 |
一般工业技术 | 1162篇 |
冶金工业 | 833篇 |
原子能技术 | 46篇 |
自动化技术 | 1089篇 |
出版年
2023年 | 56篇 |
2022年 | 115篇 |
2021年 | 183篇 |
2020年 | 130篇 |
2019年 | 174篇 |
2018年 | 211篇 |
2017年 | 135篇 |
2016年 | 163篇 |
2015年 | 133篇 |
2014年 | 194篇 |
2013年 | 351篇 |
2012年 | 309篇 |
2011年 | 346篇 |
2010年 | 254篇 |
2009年 | 261篇 |
2008年 | 271篇 |
2007年 | 275篇 |
2006年 | 200篇 |
2005年 | 193篇 |
2004年 | 167篇 |
2003年 | 170篇 |
2002年 | 144篇 |
2001年 | 85篇 |
2000年 | 96篇 |
1999年 | 71篇 |
1998年 | 232篇 |
1997年 | 156篇 |
1996年 | 98篇 |
1995年 | 107篇 |
1994年 | 78篇 |
1993年 | 70篇 |
1992年 | 58篇 |
1991年 | 45篇 |
1990年 | 31篇 |
1989年 | 31篇 |
1988年 | 37篇 |
1987年 | 34篇 |
1986年 | 19篇 |
1985年 | 28篇 |
1984年 | 20篇 |
1983年 | 15篇 |
1982年 | 25篇 |
1981年 | 29篇 |
1980年 | 22篇 |
1979年 | 21篇 |
1978年 | 17篇 |
1977年 | 26篇 |
1976年 | 45篇 |
1975年 | 13篇 |
1972年 | 13篇 |
排序方式: 共有6038条查询结果,搜索用时 0 毫秒
1.
Leibetseder Andreas Schoeffmann Klaus Keckstein Jörg Keckstein Simon 《Multimedia Tools and Applications》2022,81(5):6191-6215
Multimedia Tools and Applications - Endometriosis is a common gynecologic condition typically treated via laparoscopic surgery. Its visual versatility makes it hard to identify for non-specialized... 相似文献
2.
Simon Neumann Pin Hu Felix Bretschneider Holger Schmalz Andreas Greiner 《大分子材料与工程》2021,306(7):2100090
In this study, blends of the bio-based poly(limonene carbonate) (PLimC) with different commodity polymers are investigated in order to explore the potential of PLimC toward generating more sustainable polymer materials by reducing the amount of petro- or food-based polymers. PLimC is employed as minority component in the blends. Next to the morphology and thermal properties of the blends the impact of PLimC on the mechanical properties of the matrix polymers is studied. The interplay of incompatibility and zero-shear melt viscosity contrast determines the blend morphology, leading for all blends to a dispersed droplet morphology for PLimC. Blends with polymers of similar structure to PLimC (i.e., aliphatic/aromatic polyester) show the best performance with respect to mechanical properties, whereas blends with polystyrene or poly(methyl methacrylate) are too brittle and polyamide 12 blends show very low elongations at break. In blends with Ecoflex (poly(butylene adipate-co-terephthalate)) and Arnitel EM400 (copoly(ether ester)) with poly(butylene terephthalate) hard and polytetrahydrofuran soft segments) a threefold increase in E-modulus can be achieved, while keeping the elongation at break at reasonable high values of ≈200%, making these blends highly interesting for applications. 相似文献
3.
Sebastian Roth Peter Stockinger Jakob Steff Simon Steimle Dr. Viktor Sautner Prof. Dr. Kai Tittmann Prof. Dr. Jürgen Pleiss Prof. Dr. Michael Müller 《Chembiochem : a European journal of chemical biology》2020,21(18):2615-2619
The family of NAD(P)H-dependent short-chain dehydrogenases/reductases (SDRs) comprises numerous biocatalysts capable of C=O or C=C reduction. The highly homologous noroxomaritidine reductase (NR) from Narcissus sp. aff. pseudonarcissus and Zt_SDR from Zephyranthes treatiae, however, are SDRs with an extended imine substrate scope. Comparison with a similar SDR from Asparagus officinalis (Ao_SDR) exhibiting keto-reducing activity, yet negligible imine-reducing capability, and mining the Short-Chain Dehydrogenase/Reductase Engineering Database indicated that NR and Zt_SDR possess a unique active-site composition among SDRs. Adapting the active site of Ao_SDR accordingly improved its imine-reducing capability. By applying the same strategy, an unrelated SDR from Methylobacterium sp. 77 (M77_SDR) with distinct keto-reducing activity was engineered into a promiscuous enzyme with imine-reducing activity, thereby confirming that the ability to reduce imines can be rationally introduced into members of the “classical” SDR enzyme family. Thus, members of the SDR family could be a promising starting point for protein approaches to generate new imine-reducing enzymes. 相似文献
4.
5.
Moritz Raab Simon Maier Ralph-Uwe Dietrich 《International Journal of Hydrogen Energy》2021,46(21):11956-11968
A large-scale point to point hydrogen transport is one strategy for a prospective energy import scenario for certain countries. The case for a hydrogen transport from Australia to Japan has been addressed in several studies. However, most studies lack transparency and detailed insights into the made assumptions thus a fair evaluation of different transport pathways is challenging. To address this issue, we developed a model where a large-scale point to point hydrogen transport of liquid hydrogen is compared with the transport via liquid organic hydrogen carrier (LOHC), namely via methyl cyclohexane and hydrogenated dibenzyl toluene. We analyzed, where energy is required along the different pathways, where hydrogen losses do occur and how the costs are put together. Furthermore, the influence of hydrogen feed costs is also considered. For hydrogen production costs of 5 €2018/kgH2 the total delivery costs are in the range of 6.40– 8.10 €2018/kgH2. 相似文献
6.
7.
8.
Joshua C. Price Simon J. Levett Valentin Radu David A. Simpson Aina Mogas Barcons Christopher F. Adams Melissa L. Mather 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(22)
Fluorescent nanodiamonds (fNDs) containing nitrogen vacancy (NV) centers are promising candidates for quantum sensing in biological environments. This work describes the fabrication and implementation of electrospun poly lactic‐co‐glycolic acid (PLGA) nanofibers embedded with fNDs for optical quantum sensing in an environment, which recapitulates the nanoscale architecture and topography of the cell niche. A protocol that produces uniformly dispersed fNDs within electrospun nanofibers is demonstrated and the resulting fibers are characterized using fluorescent microscopy and scanning electron microscopy (SEM). Optically detected magnetic resonance (ODMR) and longitudinal spin relaxometry results for fNDs and embedded fNDs are compared. A new approach for fast detection of time varying magnetic fields external to the fND embedded nanofibers is demonstrated. ODMR spectra are successfully acquired from a culture of live differentiated neural stem cells functioning as a connected neural network grown on fND embedded nanofibers. This work advances the current state of the art in quantum sensing by providing a versatile sensing platform that can be tailored to produce physiological‐like cell niches to replicate biologically relevant growth environments and fast measurement protocols for the detection of co‐ordinated endogenous signals from clinically relevant populations of electrically active neuronal circuits. 相似文献
9.
On the effect of spatial variances in historical rainfall time series to CSO performance evaluation.
Historical, high-resolution rain series are the backbone of modern combined sewer overflow (CSO) structure design. These rain series are the input to the computational estimation of the performance of the measures with respect to CSO pollution abatement. However, those historical precipitation measurements are available at only a few locations. Frequently rain series have to be used from gauging stations at a significant distance. In order to judge and to compensate for this influence an estimate between rain characteristics and combined sewer outflow (CSO) performance indicators would be useful. In this paper such correlations have been sought for a collection of 37 rain series covering large areas of Europe. It was found that the mean annual rain volume can explain most of the variances for the performance indicators Number of overflows and CSO volume. For explaining the spatial differences in the efficiency of the CSO structure another rain characteristic, i.e. the maximum event with a return period of one year, is to be used. 相似文献
10.