首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   14240篇
  免费   1099篇
  国内免费   217篇
电工技术   468篇
技术理论   1篇
综合类   493篇
化学工业   2901篇
金属工艺   405篇
机械仪表   531篇
建筑科学   749篇
矿业工程   227篇
能源动力   425篇
轻工业   2439篇
水利工程   202篇
石油天然气   492篇
武器工业   52篇
无线电   1013篇
一般工业技术   2251篇
冶金工业   814篇
原子能技术   75篇
自动化技术   2018篇
  2024年   46篇
  2023年   186篇
  2022年   307篇
  2021年   517篇
  2020年   390篇
  2019年   398篇
  2018年   510篇
  2017年   576篇
  2016年   511篇
  2015年   493篇
  2014年   678篇
  2013年   1140篇
  2012年   916篇
  2011年   1007篇
  2010年   816篇
  2009年   752篇
  2008年   793篇
  2007年   725篇
  2006年   703篇
  2005年   476篇
  2004年   393篇
  2003年   374篇
  2002年   335篇
  2001年   339篇
  2000年   282篇
  1999年   260篇
  1998年   345篇
  1997年   248篇
  1996年   188篇
  1995年   171篇
  1994年   132篇
  1993年   86篇
  1992年   60篇
  1991年   47篇
  1990年   39篇
  1989年   40篇
  1988年   36篇
  1987年   20篇
  1986年   23篇
  1985年   24篇
  1984年   27篇
  1983年   28篇
  1982年   22篇
  1981年   10篇
  1980年   12篇
  1979年   11篇
  1978年   8篇
  1977年   12篇
  1976年   14篇
  1973年   7篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical...  相似文献   
2.
The noninvasive sampling of dermal interstitial fluid (ISF) for the monitoring of clinical biomarkers is a greatly appealing area of research. The identification of molecular biomarkers in biological fluids has been accelerated with -omics analyses but remains limited in ISF because of its time-consuming and complex extraction process. Here, the generation of microneedle (MN) patches made of superabsorbent acrylate-based hydrogels for the rapid sampling of dermal ISF is described to explore its proteome. In depth, iterative optimization allows the identification of novel acrylate-based compositions with the required chemical, mechanical, and biocompatibility properties allowing proteomic analysis of the extracted ISF for the first time after sampling with swelling MNs. The generated MN arrays show no cytotoxic effect, successfully cross the stratum corneum, and can collect up to 6 µL of dermal ISF in 10 min in vivo. Proteomics lead to the detection of 176 clinically relevant biomarkers in the collected samples validating the use of ISF as a relevant bodily fluid for disease monitoring and diagnostic. Importantly, it is discovered that extraction fingerprint is strongly dependent on the MNs chemistry, and thus specific biomarkers could be selectively extracted by tuning the composition of the patch, making the system versatile and specific.  相似文献   
3.

LiFe2/3Mn1/3PO4/C composite was prepared by the rheological phase reaction using LiH2PO4, Li2CO3, FePO4, Mn(Ac)2·4H2O and ascorbic acid as starting materials. The crystal structure and morphology of as-synthesized sample were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The analysis of XRD results showed that the obtained sample was single-phase with orthorhombic olivine-type structure (Pnma space group). SEM micrographs revealed that the sample was aggregates, with an irregular morphology. The initial discharge capacity was 166.9, 149.1, 139.6, 112.8, 82.93 mAh g??1 at the rate of 0.1, 0.5, 1, 2, and 10 C, respectively. And when the rate was 0.1, 0.5, 1, 2, and 10 C, the capacity retention was 92.2%, 90%, 92.9%, 97.6%, 91.5% after 50, 100, 200, 200, 500 cycles, respectively.

  相似文献   
4.
Refining ceramic microstructures to the nanometric range to minimize light scattering provides an interesting methodology for developing novel optical ceramic materials. In this work, we reported the fabrication and properties of a new nanocomposite optical ceramic of Gd2O3-MgO. The citric acid sol-gel combustion method was adopted to fabricate Gd2O3-MgO nanocomposites with fine-grain sizes, dense microstructures and homogeneous phase domains. Nanopowders with low agglomeration and improved sinterability can be obtained by elaborating Φ values. Further refining of the microstructure of the nanocomposites was achieved by elaborating the hot-pressing conditions. The sample sintered at 65 MPa and 1300 °C showed a quite high hardness value of 14.3 ± 0.2 GPa, a high transmittance of 80.3 %–84.7 % over the 3?6 μm wavelength range, due mainly to its extremely fine-grain size of Gd2O3 and MgO (93 and 78 nm, respectively) and high density.  相似文献   
5.
In this study, amaranth flour was used as an ingredient to prepare gluten-free cookies. The production process and attributes of amaranth cookies were characterised, and the potential use of amaranth flour as a functional ingredient was analysed. Cookies exhibited a non-uniform reddish brown colour and a cookie factor ratio of 4.5 ± 0.6. Storage studies indicated that after 3 weeks at room temperature cookies presented slight variations in the texture. Simulated gastrointestinal digestion of this product was able to release peptides capable of exerting potential antithrombotic and antihypertensive activities, IC50 values of 0.22 ± 0.04 and 0.23 ± 0.03 mg mL−1 protein, respectively. This work demonstrates for the first time that food made with amaranth flour exerts potential antithrombotic and antihypertensive activity. In conclusion, these amaranth cookies could be an alternative way of incorporating potentially health beneficial products for people who choose a conscious diet, including coeliac or vegan consumers.  相似文献   
6.
7.
慕星宇  王佳璐 《电子测试》2020,(10):137-138,130
本文对国内外的电视技术发展现状进行了充分的研究和分析,并对超高清电视系统的相关图像技术参数进行了分析和介绍。  相似文献   
8.
Water Resources Management - This paper aims to evaluate the possibility of using non-utilized hydraulic energy in urban water distribution systems. For this purpose, the viability and possible...  相似文献   
9.
Zhang  Xi  Wang  Xianhai  Zhao  Hongke  Ordóñez de Pablos  Patricia  Sun  Yongqiang  Xiong  Hui 《Scientometrics》2019,119(3):1311-1344
Scientometrics - Altmetrics indices are increasingly applied to measure scholarly influence in recent years because they can reflect the influence of research outputs more timely comparing with...  相似文献   
10.
Machine Learning - We propose a set of highly scalable algorithms for the combinatorial data analysis problem of seriating similarity matrices. Seriation consists of finding a permutation of data...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号