全文获取类型
收费全文 | 115132篇 |
免费 | 20920篇 |
国内免费 | 5027篇 |
专业分类
电工技术 | 6799篇 |
技术理论 | 7篇 |
综合类 | 6413篇 |
化学工业 | 27937篇 |
金属工艺 | 5123篇 |
机械仪表 | 6022篇 |
建筑科学 | 7871篇 |
矿业工程 | 2258篇 |
能源动力 | 3218篇 |
轻工业 | 11768篇 |
水利工程 | 1908篇 |
石油天然气 | 4079篇 |
武器工业 | 978篇 |
无线电 | 16242篇 |
一般工业技术 | 19447篇 |
冶金工业 | 3987篇 |
原子能技术 | 1113篇 |
自动化技术 | 15909篇 |
出版年
2024年 | 357篇 |
2023年 | 1187篇 |
2022年 | 2184篇 |
2021年 | 3387篇 |
2020年 | 3717篇 |
2019年 | 4895篇 |
2018年 | 5028篇 |
2017年 | 5646篇 |
2016年 | 5935篇 |
2015年 | 6957篇 |
2014年 | 7704篇 |
2013年 | 9601篇 |
2012年 | 7901篇 |
2011年 | 8015篇 |
2010年 | 7907篇 |
2009年 | 7696篇 |
2008年 | 7088篇 |
2007年 | 6623篇 |
2006年 | 6116篇 |
2005年 | 5137篇 |
2004年 | 4212篇 |
2003年 | 4033篇 |
2002年 | 4117篇 |
2001年 | 3696篇 |
2000年 | 2985篇 |
1999年 | 2086篇 |
1998年 | 1297篇 |
1997年 | 1031篇 |
1996年 | 909篇 |
1995年 | 733篇 |
1994年 | 616篇 |
1993年 | 484篇 |
1992年 | 390篇 |
1991年 | 281篇 |
1990年 | 229篇 |
1989年 | 175篇 |
1988年 | 138篇 |
1987年 | 94篇 |
1986年 | 101篇 |
1985年 | 60篇 |
1984年 | 44篇 |
1983年 | 50篇 |
1982年 | 42篇 |
1981年 | 33篇 |
1980年 | 22篇 |
1979年 | 20篇 |
1978年 | 11篇 |
1976年 | 19篇 |
1975年 | 11篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
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
44.
Simulating the psychological experience of human vision,a road extraction model based on the format tower is proposed to extract the road in the high resolution remote sensing image from the perspective of morphology.Firstly,based on the spectral and texture information,the suspected road targets are extracted by using segmentation technology.Then these targets are classified according to their reliability and extract the road targets for each category.Finally,three types of identified road information are verified and merged,and the continuous smooth road extraction results are obtained.Experiments on real high resolution images show that the results are consistent with the visual perception of the human eye,and the overall classification accuracy is higher,indicating that the algorithm is effective and feasible and has good use value. 相似文献
45.
2A12铝合金化学铣切加工工艺探讨 总被引:1,自引:0,他引:1
为了精确加工2Al2铝合金,探讨了化铣时间和温度对其化铣速率及表面粗糙度的影响,采用现代技术对化铣工件的力学性能进行了测试与分析.结果表明:延长非化铣部位保护胶固化时间并使保护部位向非加工面位移3~5 mm可很好地解决未化铣区域的腐蚀问题;随化铣时间的延长,化铣速率降低,且化铣温度与化铣速率呈现正相关性;化铣表面的粗糙度随化铣时间的延长而增加,随化铣温度的升高呈先减小后增加的趋势;化铣后材料的抗拉强度和屈服强度均有所提高. 相似文献
46.
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
47.
采用突水系数法对象山煤矿北一采区11#煤层突水危险性进行了预测,结果显示,北一采区西北角、东南角属于相对安全区,突水系数0.06 MPa/m,北一采区北部B6孔附近为相对危险区,突水系数在0.1~0.119 MPa/m之间,其它区域处在临界区。该研究成果可为矿井防治水提供参考依据。 相似文献
48.
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
49.
基于DTW改进算法的孤立词识别系统的仿真与分析 总被引:5,自引:0,他引:5
传统的DTW算法在进行孤立词语音识别时着重于时间规整和语音测度的计算,而没有对数据的可靠性和有效性进行分析。本文提出了一种改进的端点检测算法,并采用一种改进的DTW算法,在计算机上进行了仿真。实验结果表明采用改进后的DTW算法有效的降低了识别时间和存储数据量,提高了系统性能。 相似文献
50.
基于承包商预期收益不变的不平衡报价模型 总被引:1,自引:0,他引:1
在招标实践中,通常采用最低价中标原则,使得投标人不得不压低其投标价格。基于承包商预期收益不变的不平衡报价模型,是在“工程量清单报价”的条件下,考虑到施工中工程量的变化及施工顺序的影响,体现了资金的时间价值,在保持承包商预期收益不变的前提下,通过调整各分项工程的单价,来降低工程报价,以增加中标机会而建立的。所建立的模型简单,易于操作,并配以具体的工程实例,通过计算机求得其最优解,可供承包商投标报价时参考。 相似文献