全文获取类型
收费全文 | 219702篇 |
免费 | 29653篇 |
国内免费 | 9611篇 |
专业分类
电工技术 | 13268篇 |
技术理论 | 3篇 |
综合类 | 13374篇 |
化学工业 | 43930篇 |
金属工艺 | 11077篇 |
机械仪表 | 12425篇 |
建筑科学 | 16066篇 |
矿业工程 | 5107篇 |
能源动力 | 6167篇 |
轻工业 | 20228篇 |
水利工程 | 4185篇 |
石油天然气 | 8609篇 |
武器工业 | 1628篇 |
无线电 | 29361篇 |
一般工业技术 | 31666篇 |
冶金工业 | 9188篇 |
原子能技术 | 2182篇 |
自动化技术 | 30502篇 |
出版年
2024年 | 782篇 |
2023年 | 2667篇 |
2022年 | 5411篇 |
2021年 | 7547篇 |
2020年 | 6590篇 |
2019年 | 7179篇 |
2018年 | 7621篇 |
2017年 | 8766篇 |
2016年 | 8623篇 |
2015年 | 11056篇 |
2014年 | 12927篇 |
2013年 | 16014篇 |
2012年 | 15276篇 |
2011年 | 16112篇 |
2010年 | 14993篇 |
2009年 | 14550篇 |
2008年 | 13802篇 |
2007年 | 13320篇 |
2006年 | 12291篇 |
2005年 | 10295篇 |
2004年 | 7466篇 |
2003年 | 6619篇 |
2002年 | 6710篇 |
2001年 | 5774篇 |
2000年 | 4957篇 |
1999年 | 4182篇 |
1998年 | 3020篇 |
1997年 | 2676篇 |
1996年 | 2341篇 |
1995年 | 1932篇 |
1994年 | 1514篇 |
1993年 | 1220篇 |
1992年 | 952篇 |
1991年 | 741篇 |
1990年 | 605篇 |
1989年 | 498篇 |
1988年 | 396篇 |
1987年 | 279篇 |
1986年 | 236篇 |
1985年 | 185篇 |
1984年 | 135篇 |
1983年 | 93篇 |
1982年 | 99篇 |
1981年 | 79篇 |
1980年 | 77篇 |
1979年 | 45篇 |
1978年 | 43篇 |
1977年 | 42篇 |
1976年 | 62篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
61.
Physical Stability of Octenyl Succinate–Modified Polysaccharides and Whey Proteins for Potential Use as Bioactive Carriers in Food Systems 下载免费PDF全文
The high cost and potential toxicity of biodegradable polymers like poly(lactic‐co‐glycolic)acid (PLGA) has increased the interest in natural and modified biopolymers as bioactive carriers. This study characterized the physical stability (water sorption and state transition behavior) of selected starch and proteins: octenyl succinate–modified depolymerized waxy corn starch (DWxCn), waxy rice starch (DWxRc), phytoglycogen, whey protein concentrate (80%, WPC), whey protein isolate (WPI), and α‐lactalbumin (α‐L) to determine their potential as carriers of bioactive compounds under different environmental conditions. After enzyme modification and particle size characterization, glass transition temperature and moisture isotherms were used to characterize the systems. DWxCn and DWxRc had increased water sorption compared to native starch. The level of octenyl succinate anhydrate (OSA) modification (3% and 7%) did not reduce the water sorption of the DWxCn and phytoglycogen samples. The Guggenheim–Andersen–de Boer model indicated that native waxy corn had significantly (P < 0.05) higher water monolayer capacity followed by 3%‐OSA‐modified DWxCn, WPI, 3%‐OSA‐modified DWxRc, α‐L, and native phytoglycogen. WPC had significantly lower water monolayer capacity. All Tg values matched with the solid‐like appearance of the biopolymers. Native polysaccharides and whey proteins had higher glass transition temperature (Tg) values. On the other hand, depolymerized waxy starches at 7%‐OSA modification had a “melted” appearance when exposed to environments with high relative humidity (above 70%) after 10 days at 23 °C. The use of depolymerized and OSA‐modified polysaccharides blended with proteins created more stable blends of biopolymers. Hence, this biopolymer would be suitable for materials exposed to high humidity environments in food applications. 相似文献
62.
This paper considers a novel distributed iterative learning consensus control algorithm based on neural networks for the control of heterogeneous nonlinear multiagent systems. The system's unknown nonlinear function is approximated by suitable neural networks; the approximation error is countered by a robust term in the control. Two types of control algorithms, both of which utilize distributed learning laws, are provided to achieve consensus. In the provided control algorithms, the desired reference is considered to be an unknown factor and then estimated using the associated learning laws. The consensus convergence is proven by the composite energy function method. A numerical simulation is ultimately presented to demonstrate the efficacy of the proposed control schemes. 相似文献
63.
64.
65.
通过对CSFB语音方案原理的分析,结合业务模型及网络安全等方面的考虑,提出了一种支持4G CSFB的MSC改造规模预测方法,为端局后续建设提供了参考. 相似文献
66.
67.
This study assessed the collection efficiency (CE) of two popularly used sampling devices (BioSampler and Coriolis sampler) for fungal aerosols. Phosphate‐buffered saline (PBS) supplemented with or without surfactant (Tween‐20, Tween‐80, or Triton X‐100) and antifoam agent was prepared and used as collection liquids. The agar impactor (BioStage) was simultaneously operated with liquid‐based samplers to collect fungi from seven sites located at a university building, public library, and animal farming. Fungal concentrations determined by liquid samplers were divided by those by BioStage, and the ratio values represented CE. Results indicate that the CE of BioSampler was superior to that of Coriolis (P = 0.0001) and the PBS containing surfactant collected fungi better than that without surfactant (P < 0.0001), whereas antifoam agent showed no influence (P = 0.8). Moreover, fungal concentrations determined by BioSampler with surfactant‐added PBS were statistically indifferent from those by BioStage (P > 0.05) with a Spearman correlation coefficient of 0.81‐0.83 (P < 0.01). In addition to sampler and collection liquid, sampling location was also identified as a significant CE factor (P = 0.006), implying potential influences by fungal genera in the studied fields. Overall, BioSampler with surfactant‐supplemented PBS (eg, Triton X‐100) is recommended considering the great CE and compatibility with a variety of analytical assays. 相似文献
68.
Alfredo M. Gravagnuolo Eden Morales‐Narváez Charlene Regina Santos Matos Sara Longobardi Paola Giardina Arben Merkoçi 《Advanced functional materials》2015,25(38):6084-6092
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self‐assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self‐assembling of Vmh2 at liquid–solid interfaces is achieved (in 2 min). The Vmh2‐coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti‐immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self‐assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications. 相似文献
69.
该文针对当前矿井炮掘巷道大断面掘进普遍存在掘进施工较慢的实际,结合公司实际情况,有针对性地提出了解决的办法。 相似文献
70.
Seong‐Hee Kim 《Quality and Reliability Engineering International》2015,31(6):923-934
We present a distribution‐free tabular cumulative sum chart for monitoring the variability of an autocorrelated process. A quantity known as the asymptotic variance parameter is employed as a measure of the variability, and a distribution‐free tabular cumulative sum chart is applied to variance estimates calculated from batches of nonoverlapping samples. The proposed chart is applicable to a stationary process with a general marginal distribution and a general autocorrelation structure. It also determines control limits analytically without trial‐and‐error simulations. The performance of the proposed chart is tested on stationary processes with both normal and nonnormal marginals with various autocorrelation structures. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献