全文获取类型
收费全文 | 94112篇 |
免费 | 14664篇 |
国内免费 | 67篇 |
专业分类
电工技术 | 1055篇 |
综合类 | 43篇 |
化学工业 | 30959篇 |
金属工艺 | 1221篇 |
机械仪表 | 1749篇 |
建筑科学 | 3507篇 |
矿业工程 | 109篇 |
能源动力 | 2412篇 |
轻工业 | 17331篇 |
水利工程 | 794篇 |
石油天然气 | 325篇 |
武器工业 | 3篇 |
无线电 | 8906篇 |
一般工业技术 | 19257篇 |
冶金工业 | 9474篇 |
原子能技术 | 274篇 |
自动化技术 | 11424篇 |
出版年
2024年 | 124篇 |
2023年 | 578篇 |
2022年 | 1795篇 |
2021年 | 2534篇 |
2020年 | 2704篇 |
2019年 | 4458篇 |
2018年 | 4723篇 |
2017年 | 4998篇 |
2016年 | 5670篇 |
2015年 | 5286篇 |
2014年 | 5732篇 |
2013年 | 8776篇 |
2012年 | 5922篇 |
2011年 | 5961篇 |
2010年 | 5299篇 |
2009年 | 5085篇 |
2008年 | 4490篇 |
2007年 | 4076篇 |
2006年 | 3339篇 |
2005年 | 2800篇 |
2004年 | 2636篇 |
2003年 | 2500篇 |
2002年 | 2326篇 |
2001年 | 1851篇 |
2000年 | 1736篇 |
1999年 | 1241篇 |
1998年 | 3073篇 |
1997年 | 2022篇 |
1996年 | 1381篇 |
1995年 | 789篇 |
1994年 | 665篇 |
1993年 | 670篇 |
1992年 | 284篇 |
1991年 | 266篇 |
1990年 | 195篇 |
1989年 | 212篇 |
1988年 | 211篇 |
1987年 | 203篇 |
1986年 | 181篇 |
1985年 | 197篇 |
1984年 | 151篇 |
1983年 | 110篇 |
1982年 | 117篇 |
1981年 | 138篇 |
1980年 | 140篇 |
1979年 | 82篇 |
1978年 | 83篇 |
1977年 | 216篇 |
1976年 | 396篇 |
1975年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
141.
142.
Moutafis Panagiotis García-García Francisco Mavrommatis George Vassilakopoulos Michael Corral Antonio Iribarne Luis 《Distributed and Parallel Databases》2021,39(3):733-784
Distributed and Parallel Databases - Given two datasets of points (called Query and Training), the Group (K) Nearest-Neighbor (GKNN) query retrieves (K) points of the Training with the smallest sum... 相似文献
143.
Software Quality Journal - Energy consumption of software has been becoming increasingly significant, since it can vary according to how the software has been developed. In recent years, developers... 相似文献
144.
C García Barroso R Cela Torrijos J A Pérez-Bustamante 《Zeitschrift für Lebensmittel-Untersuchung und -Forschung》1987,185(4):307-314
The different groups and/or classes among phenolic acids and aldehydes identified during the elaboration process of "fino" sherry wine have been studied. The study was carried out using different processes during the elaboration of the wine and we have attempted to establish whether the different treatments of the grape affect these groupings. The study was undertaken by means of cluster and multifactorial analysis on the data obtained by the quantitative determination of phenolic acids and aldehydes during vinification and in experiments carried out on the grape under different mechanical treatments. The analysis of phenolic acids and aldehydes was done with HPLC, using a C-18 mu-Bondapak and a stepwise composite gradient. The samples were previously extracted with ethylic ether. 相似文献
145.
J. M. Martínez 《Computing》1987,39(4):307-325
We introduce a new method for solving Nonlinear Least Squares problems when the Jacobian matrix of the system is large and sparse. The main features of the new method are the following:
- The Gauss-Newton equation is “partially” solved at each iteration using a preconditioned Conjugate Gradient algorithm.
- The new point is obtained using a two-dimensional trust region scheme, similar to the one introduced by Bulteau and Vial.
146.
Maria Buuales Maria Cristina Ballesteros-Briones Manuela Gonzalez-Aparicio Sandra Hervas-Stubbs Eva Martisova Uxua Mancheo Ana Ricobaraza Sara Lumbreras Cristian Smerdou Ruben Hernandez-Alcoceba 《International journal of molecular sciences》2021,22(8)
Immune checkpoint inhibitors (ICIs) have demonstrated remarkable efficacy in a growing number of malignancies. However, overcoming primary or secondary resistances is difficult due to pharmacokinetics issues and side effects associated with high systemic exposure. Local or regional expression of monoclonal antibodies (mAbs) using gene therapy vectors can alleviate this problem. In this work, we describe a high-capacity adenoviral vector (HCA-EFZP-aPDL1) equipped with a mifepristone-inducible system for the controlled expression of an anti-programmed death ligand 1 (PD-L1) blocking antibody. The vector was tested in an immune-competent mouse model of colorectal cancer based on implantation of MC38 cells. A single local administration of HCA-EFZP-aPDL1 in subcutaneous lesions led to a significant reduction in tumor growth with minimal release of the antibody in the circulation. When the vector was tested in a more stringent setting (rapidly progressing peritoneal carcinomatosis), the antitumor effect was marginal even in combination with other immune-stimulatory agents such as polyinosinic-polycytidylic acid (pI:C), blocking mAbs for T cell immunoglobulin, mucin-domain containing-3 (TIM-3) or agonistic mAbs for 4-1BB (CD137). In contrast, macrophage depletion by clodronate liposomes enhanced the efficacy of HCA-EFZP-aPDL1. These results highlight the importance of addressing macrophage-associated immunoregulatory mechanisms to overcome resistance to ICIs in the context of colorectal cancer. 相似文献
147.
The conditions for current oscillations in austenitic stainless steel (AISI Type 303) in 1M H2SO4 containing Cl? ions are given. The periodic oscillations are produced in a close potential range determined at the active-passive transition region. It requires a non-homogeneous distribution of inclusions and carbides at the metal surface and a concentration range of Cl? ion where active and passive areas coexist on the metal surface. The constraints at the surface determining these two regions are related to the Cl? ion competitive adsorption and the local accumulation of corrosion products. Electrochemical data and SEM observations are correlated. 相似文献
148.
The influence of nonsolvent, crystallinity of the polymer film, and addition of dodecane (a poor solvent for the polymer and for the nonsolvent) on the morphology of polylactides films has been investigated and was related to phase separation behavior. Both amorphous poly‐DL ‐lactide (PDLLA) and crystalline poly‐L ‐lactide (PLLA) were dissolved in dichloromethane, and subsequently films were made by immersion in nonsolvent baths. PDLLA gave dense films without any internal structure, since the structure was not solidified by crystallization or glassification. PLLA films show varying structure depending on the nonsolvent. With methanol, asymmetric morphologies were observed as a result from combined liquid‐liquid demixing and crystallization, while with water symmetric spherulitic structures were formed. As a next step, dodecane was added, which is not miscible with the nonsolvent, and we found it to have a strong influence on the morphology of the films. The PDLLA films with dodecane did not collapse: a closed cell structure was obtained. In PLLA films, dodecane speeds up phase separation and induces faster crystallization in the films, and the porosity, size of the pores, and interconnectivity increased. When the PLLA solutions were subjected to a heat pretreatment, crystallization could be postponed, which yielded a cellular structure around dodecane, which did not contain spherulites anymore. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 959–971, 2007 相似文献
149.
The solubility parameter of poly(ethylene oxide) at 25°C has been determined using the method developed by DiPaola-Baranyi and Guillet, by the extrapolation of the values of the interaction parameter χ, at high temperatures, ranging from 70°–90°, 90°–110° and 110°–130°C down to 25°C. The values of the solubility parameter obtained, depending on the temperature ranges employed, are 9.8, 9.9 and 10.1, respectively. 相似文献
150.
Hydrotalcites in the nitrate form were prepared using microwave irradiation in the hydrotreatment step. The surface area (BET) of nitrated hydrotalcites was evaluated. Solids were characterized by atomic absorption, X-ray diffraction and BET analysis. Thermal pretreatment temperature determined the surface area of the hydrotalcites. 相似文献