全文获取类型
收费全文 | 1740篇 |
免费 | 178篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 17篇 |
综合类 | 2篇 |
化学工业 | 508篇 |
金属工艺 | 23篇 |
机械仪表 | 42篇 |
建筑科学 | 62篇 |
矿业工程 | 2篇 |
能源动力 | 70篇 |
轻工业 | 282篇 |
水利工程 | 22篇 |
石油天然气 | 6篇 |
无线电 | 112篇 |
一般工业技术 | 262篇 |
冶金工业 | 137篇 |
原子能技术 | 13篇 |
自动化技术 | 362篇 |
出版年
2024年 | 10篇 |
2023年 | 29篇 |
2022年 | 88篇 |
2021年 | 110篇 |
2020年 | 62篇 |
2019年 | 78篇 |
2018年 | 89篇 |
2017年 | 91篇 |
2016年 | 116篇 |
2015年 | 66篇 |
2014年 | 94篇 |
2013年 | 145篇 |
2012年 | 112篇 |
2011年 | 147篇 |
2010年 | 82篇 |
2009年 | 77篇 |
2008年 | 83篇 |
2007年 | 64篇 |
2006年 | 58篇 |
2005年 | 40篇 |
2004年 | 34篇 |
2003年 | 23篇 |
2002年 | 32篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 33篇 |
1997年 | 22篇 |
1996年 | 24篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 12篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1922条查询结果,搜索用时 15 毫秒
1.
Vanessa Modelski Schatkoski Thaís Larissa do Amaral Montanheiro Beatriz Rossi Canuto de Menezes Raissa Monteiro Pereira Karla Faquine Rodrigues Renata Guimarães Ribas Diego Morais da Silva Gilmar Patrocínio Thim 《Ceramics International》2021,47(3):2999-3012
Studies related to biomaterials that stimulate the repair of living tissue have increased considerably, improving the quality of many people's lives that require surgery due to traumatic accidents, bone diseases, bone defects, and reconstructions. Among these biomaterials, bioceramics and bioactive glasses (BGs) have proved to be suitable for coating materials, cement, scaffolds, and nanoparticles, once they present good biocompatibility and degradability, able to generate osteoconduction on the surrounding tissue. However, the role of biomaterials in hard tissue engineering is not restricted to a structural replacement or for guiding tissue regeneration. Nowadays, it is expected that biomaterials develop a multifunctional role when implanted, orchestrating the process of tissue regeneration and providing to the body the capacity to heal itself. In this way, the incorporation of specific metal ions in bioceramics and BGs structure, including magnesium, silver, strontium, lithium, copper, iron, zinc, cobalt, and manganese are currently receiving enhanced interest as biomaterials for biomedical applications. When an ion is incorporated into the bioceramic structure, a new category of material is created, which has several unique properties that overcome the disadvantages of primitive material and favors its use in different biomedical applications. The doping can enhance handling properties, angiogenic and osteogenic performance, and antimicrobial activity. Therefore, this review aims to summarize the effect of selected metal ion dopants into bioceramics and silicate-based BGs in bone tissue engineering. Furthermore, new applications for doped bioceramics and BGs are highlighted, including cancer treatment and drug delivery. 相似文献
2.
Martinez-Yelmo Isaias Alvarez-Horcajo Joaquin Briso-Montiano Miguel Lopez-Pajares Diego Rojas Elisa 《Telecommunication Systems》2019,72(4):555-565
Telecommunication Systems - The Software-Defined Networking (SDN) architecture decouples the control plane from the data plane, but it does not explicitly state where the control should be located.... 相似文献
3.
Precil Diego M. M. Neves Fernanda M. Freitas Christiane A. Kojima Beatriz L. Carmello Rodrigo Bazan Pasqual Barretti Luis C. Martin 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(1):143-145
Antibiotics are potentially a cause of neurotoxicity in dialysis patients, the most common are the beta‐lactams as ceftazidime and cefepime, and few cases have been reported after piperacillin/tazobactam use. This report presents a case of a hypertensive and diabetic 67‐year‐old woman in regular hemodialysis, which previously had a stroke. She was hospitalized presenting pneumonia, which was initially treated with cefepime. Two days after treatment, she presented dysarthria, left hemiparesis, ataxia, and IX and X cranial nerves paresis. Computed tomography showed no acute lesions and cefepime neurotoxicity was hypothesized, and the antibiotic was replaced by piperacillin/tazobactam. The neurologic signs disappeared; however, 4 days after with piperacillin/tazobactam treatment, the neurological manifestations returned. A new computed tomography showed no new lesions, and the second antibiotic regimen withdrawn. After two hemodialysis sessions, the patient completely recovered from neurological manifestations. The patient presented sequentially neurotoxicity caused by two beta‐lactams antibiotics. This report meant to alert clinicians that these antibiotics have dangerous neurological effects in chronic kidney disease patients. 相似文献
4.
5.
Participating media with an inhomogeneous index of refraction make light follow curved paths. Simulating this in a global
illumination environment has usually been neglected due to the complexity of the calculations involved, sacrificing accurate
physical simulations for efficient visual results.
This paper aims to simulate non-linear media in a more reasonable time than previous works without losing physical correctness.
Accuracy is achieved by solving the Eikonal equation of geometrical optics, which describes the path followed by a light beam
that traverses a non-linear medium. This equation is used in the context of a photon mapping extension. 相似文献
6.
AP Krapcho E Menta A Oliva R Di Domenico L Fiocchi ME Maresch CE Gallagher MP Hacker G Beggiolin FC Giuliani G Pezzoni S Spinelli 《Canadian Metallurgical Quarterly》1998,41(27):5429-5444
The synthesis and antitumor evaluation of 2, 5-disubstituted-indazolo[4,3-gh]isoquinolin-6(2H)-ones (9-aza-APs) are described. The key intermediates in the synthesis are benz[g]isoquinoline-5,10-diones which are substituted at positions 6 and 9 with groups of different nucleofugacity for SNAr displacements. The initial displacement of fluoride by a substituted hydrazine leads to the pyrazole analogues. Substitution of the remaining leaving group by an amine or BOC-protected amines leads to the 9-aza-APs 12. These analogues were converted into their maleate or hydrochloride salts 13. In two cases, namely, 13x and 13z, sidearm buildup was also employed in the synthetic pathway. In vitro evaluation of 9-aza-APs against the human colon tumor cell line LoVo uncovered for most of the compounds a cytotoxic potency lower than that of DuP-941 or mitoxantrone and comparable to that of doxorubicin. Only analogues 13c, 13n, and 13ff were as cytotoxic as DuP-941. Interestingly, while DuP-941 was highly cross-resistant in the LoVo cell line resistant to doxorubicin (LoVo/Dx), the 9-aza-APs carrying a distal lipophilic tertiary amine moiety in both chains were capable of overcoming the MDR resistance induced in this cell line. The 9-aza-APs show outstanding in vivo antitumor activity against both systemic P388 murine leukemia and MX-1 human mammary carcinoma transplanted in nude mice. At their optimal dosages, congeners 13a-c, 13f, 13n, 13q, 13x, and 13dd were highly effective against P388 leukemia with T/C% of 200-381, while the T/C% value of DuP-941 was 147. In the MX-1 tumor model, 24 compounds elicited percentages of tumor weight inhibitions (TWI) ranging from 50% to 99%. Congeners 13d, 13k, 13l, 13x, 13z, and 13ee emerged as the most effective ones, with TWI% 96, simliar to that of DuP-941 (TWI% = 95). On the basis of their efficacy profile in additional experimental tumors and lack of cardiotoxicity in preclinical models, two congeners have surfaced as potential clinical candidates. 相似文献
7.
8.
Experiences of acid cleaning and passivation treatments of copper alloy tubes are described. The suitability of corrosion monitoring to follow each step of such operation is demonstrated. 相似文献
9.
This study investigates the whole-body vibration exposure in kite surfing, alpine skiing, snowboarding and cycling. The vibration exposure was experimentally evaluated following the ISO 2631 guidelines. Results evidenced that the most critical axis is the vertical one. The weighted vibration levels are always larger than 2.5 m/s2 and the vibration dose values are larger than 25 m/s1.75. The exposure limit values of the EU directive are reached after 8–37 min depending on the sport. The vibration magnitude is influenced by the athletes’ speed, by their skill level and sometimes by the equipment. The large vibration values suggest that the practice of sport activities may be a confounding factor in the aetiology of vibration-related diseases. 相似文献
10.