全文获取类型
收费全文 | 1435篇 |
免费 | 150篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 23篇 |
综合类 | 1篇 |
化学工业 | 464篇 |
金属工艺 | 13篇 |
机械仪表 | 29篇 |
建筑科学 | 61篇 |
矿业工程 | 3篇 |
能源动力 | 44篇 |
轻工业 | 207篇 |
水利工程 | 12篇 |
石油天然气 | 1篇 |
无线电 | 119篇 |
一般工业技术 | 234篇 |
冶金工业 | 108篇 |
原子能技术 | 8篇 |
自动化技术 | 260篇 |
出版年
2024年 | 2篇 |
2023年 | 32篇 |
2022年 | 93篇 |
2021年 | 108篇 |
2020年 | 56篇 |
2019年 | 63篇 |
2018年 | 71篇 |
2017年 | 58篇 |
2016年 | 79篇 |
2015年 | 57篇 |
2014年 | 89篇 |
2013年 | 117篇 |
2012年 | 109篇 |
2011年 | 114篇 |
2010年 | 84篇 |
2009年 | 41篇 |
2008年 | 64篇 |
2007年 | 53篇 |
2006年 | 48篇 |
2005年 | 43篇 |
2004年 | 22篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 30篇 |
1997年 | 21篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有1587条查询结果,搜索用时 15 毫秒
991.
Stefano Menghini Ping Shu Ho Tinotenda Gwisai Simone Schuerle 《International journal of molecular sciences》2021,22(2)
Interest has grown in harnessing biological agents for cancer treatment as dynamic vectors with enhanced tumor targeting. While bacterial traits such as proliferation in tumors, modulation of an immune response, and local secretion of toxins have been well studied, less is known about bacteria as competitors for nutrients. Here, we investigated the use of a bacterial strain as a living iron chelator, competing for this nutrient vital to tumor growth and progression. We established an in vitro co-culture system consisting of the magnetotactic strain Magnetospirillum magneticum AMB-1 incubated under hypoxic conditions with human melanoma cells. Siderophore production by 108 AMB-1/mL in human transferrin (Tf)-supplemented media was quantified and found to be equivalent to a concentration of 3.78 µM ± 0.117 µM deferoxamine (DFO), a potent drug used in iron chelation therapy. Our experiments revealed an increased expression of transferrin receptor 1 (TfR1) and a significant decrease of cancer cell viability, indicating the bacteria’s ability to alter iron homeostasis in human melanoma cells. Our results show the potential of a bacterial strain acting as a self-replicating iron-chelating agent, which could serve as an additional mechanism reinforcing current bacterial cancer therapies. 相似文献
992.
Luca Tonella Valentina Pala Renata Ponti Marco Rubatto Giuseppe Gallo Luca Mastorino Gianluca Avallone Martina Merli Andrea Agostini Paolo Fava Luca Bertero Rebecca Senetta Simona Osella-Abate Simone Ribero Maria Teresa Fierro Pietro Quaglino 《International journal of molecular sciences》2021,22(9)
Melanoma is one of the most aggressive skin cancers. The 5-year survival rate of stage III melanoma patients ranges from 93% (IIIA) to 32% (IIID) with a high risk of recurrence after complete surgery. The introduction of target and immune therapies has dramatically improved the overall survival, but the identification of patients with a high risk of relapse who will benefit from adjuvant therapy and the determination of the best treatment choice remain crucial. Currently, patient prognosis is based on clinico-pathological features, highlighting the urgent need of predictive and prognostic markers to improve patient management. In recent years, many groups have focused their attention on identifying molecular biomarkers with prognostic and predictive potential. In this review, we examined the main candidate biomarkers reported in the literature. 相似文献
993.
Arianna De Nicola Simone Gitto Paolo Mancuso 《Expert systems with applications》2012,39(12):10495-10499
One of the main problems in efficiency analysis is to determinate the environmental variables that have an impact on the production process. This paper shows that applying bootstrap to data envelopment analysis (DEA) before performing classification and regression trees (CART) increase the quality of the results. In particular, employing data on the Italian Health System, the paper highlights that bias corrected DEA allows to individuate variables affecting health efficiency which would remain undiscovered when the traditional DEA model is applied. 相似文献
994.
995.
Cantoro M Hofmann S Pisana S Scardaci V Parvez A Ducati C Ferrari AC Blackburn AM Wang KY Robertson J 《Nano letters》2006,6(6):1107-1112
We report surface-bound growth of single-wall carbon nanotubes (SWNTs) at temperatures as low as 350 degrees C by catalytic chemical vapor deposition from undiluted C2H2. NH3 or H2 exposure critically facilitates the nanostructuring and activation of sub-nanometer Fe and Al/Fe/Al multilayer catalyst films prior to growth, enabling the SWNT nucleation at lower temperatures. We suggest that carbon nanotube growth is governed by the catalyst surface without the necessity of catalyst liquefaction. 相似文献
996.
Qusay F. Alsalhy Khalid T. Rashid Wallaă A. Noori S. Simone A. Figoli E. Drioli 《应用聚合物科学杂志》2012,124(3):2087-2099
Poly(vinyl chloride) (PVC) hollow‐fiber membranes were spun by a dry/wet phase‐inversion technique from dopes containing 15 wt % PVC to achieve membranes with different pore sizes for ultrafiltration (UF) applications. The effects of the N,N‐dimethylacetamide (DMAc) concentration in the internal coagulant on the structural morphology, separation performance, and mechanical properties of the produced PVC hollow fibers were investigated. The PVC membranes were characterized by scanning electron microscopy, average pore size, pore size distribution, void volume fraction measurements, and solubility parameter difference. Moreover, the UF experiments were conducted with pure water and aqueous solutions of poly(vinyl pyrrolidone) as feeds. The mechanical properties of the PVC hollow‐fiber membranes were discussed in terms of the tensile strength and Young's modulus. It was found that the PVC membrane morphology changed from thin, fingerlike macrovoids at the inner edge to fully spongelike structure with DMAc concentration in the internal coagulant. The effective pores showed a wide distribution, between 0.2 and 1.1 μm, for the membranes prepared with H2O as the internal coagulant and a narrow distribution, between 0.114 and 0.135 μm, with 50 wt % DMAc. The results illustrate that the difference in the membrane performances was dependent on the DMAc concentration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
997.
Caterina Viglianisi Lavinia Simone Stefano Menichetti 《Advanced Synthesis \u0026amp; Catalysis》2012,354(1):77-82
A simple procedure for the one‐pot transformation of 2‐N‐tosylamino diselenides into benzo[b][1,4]selenazines has been established. The data collected indicate that the six‐membered heterocyclic ring is the result of a [4+2] cycloaddition reaction of a transient electron‐poor o‐iminoselenoquinone, acting as diene, with an electron‐rich alkene, performing as dienophile. The key step of the synthesis is a 1,4‐elimination at selenium of a selenolate ion, leading to the generation of the heterodiene, that requires catalytic amounts of copper(II) trifluoromethanesulfonate, for the activation of the selenium‐selenium bond. 相似文献
998.
999.
The results of an experimental investigation on the exchange of radiant energy in the infrared band (λ = 4–100 μm) between the walls of a building and the surrounding environment, constituted in part by the sky and in part by the ground, are presented in this paper. The measures were obtained on a purpose built test module for studies and research on building energy. Through measurements of infrared radiation on a South facing vertical wall and on a horizontal roof, and of the relative surface temperatures, the radiant field between these surfaces and the outdoor environment was resolved in conditions of clear hourly diurnal and nocturnal sky. The investigation allowed for the determination of the hourly values of the radiative heat transfer coefficients between the vertical wall and the sky, between the vertical wall and the ground and between the horizontal roof and the sky. Furthermore, EN ISO 13790:2008, which is used for the evaluation of energy requirements of building air-conditioning, was considered and the various contributions used in order to evaluate the radiative exchange with the experimentally obtained values were compared. 相似文献
1000.
Cassio Barbosa Simone Kessler de Barros Ibrahim de Cerqueira Abud Joneo Lopes do Nascimento Sheyla Santana de Carvalho 《Journal of Failure Analysis and Prevention》2012,12(6):654-659
In general, boilers are subjected to aggressive environmental conditions and, for this reason, there is a real necessity of controlling some parameters such as quality of input water, amount and types of addition agents used in the water, and operational conditions of the equipment (pressure and temperature). The lack of control of these and other parameters can cause loss of performance of the boiler by higher amount of fuel consumption, loss of efficiency, or even rupture of components, causing severe accidents. This study has as purpose the failure analysis in a pipe of the lateral wall of a boiler, known as aqua tubular, of an aircraft carrier flat top boat during a test in sea. The material of the pipes, according to preliminary information, is ASTM 192 steel, which is adequate for this kind of application. Through microstructural analysis in important regions for the study of this failure and earlier information about equipment operation, the cause of rupture of the pipe, which was changed only 50?h before the accident, was analyzed. It was observed that incrustations, corrosion pits in the walls of the pipe, and high temperatures together with microstructural changes were the probable causes of the pipe rupture. It can also be concluded that the analyzed failure had no relation with the quality of the material or the fabrication process of the component. 相似文献