全文获取类型
收费全文 | 28686篇 |
免费 | 2599篇 |
国内免费 | 1413篇 |
专业分类
电工技术 | 1736篇 |
技术理论 | 1篇 |
综合类 | 2273篇 |
化学工业 | 4892篇 |
金属工艺 | 1749篇 |
机械仪表 | 1813篇 |
建筑科学 | 2345篇 |
矿业工程 | 797篇 |
能源动力 | 784篇 |
轻工业 | 1946篇 |
水利工程 | 581篇 |
石油天然气 | 1406篇 |
武器工业 | 272篇 |
无线电 | 3162篇 |
一般工业技术 | 3384篇 |
冶金工业 | 1268篇 |
原子能技术 | 255篇 |
自动化技术 | 4034篇 |
出版年
2024年 | 117篇 |
2023年 | 404篇 |
2022年 | 646篇 |
2021年 | 1003篇 |
2020年 | 734篇 |
2019年 | 703篇 |
2018年 | 747篇 |
2017年 | 785篇 |
2016年 | 702篇 |
2015年 | 1068篇 |
2014年 | 1233篇 |
2013年 | 1488篇 |
2012年 | 1710篇 |
2011年 | 1829篇 |
2010年 | 1692篇 |
2009年 | 1759篇 |
2008年 | 1638篇 |
2007年 | 1596篇 |
2006年 | 1765篇 |
2005年 | 1439篇 |
2004年 | 1109篇 |
2003年 | 1200篇 |
2002年 | 1437篇 |
2001年 | 1223篇 |
2000年 | 793篇 |
1999年 | 806篇 |
1998年 | 572篇 |
1997年 | 459篇 |
1996年 | 454篇 |
1995年 | 396篇 |
1994年 | 283篇 |
1993年 | 243篇 |
1992年 | 179篇 |
1991年 | 112篇 |
1990年 | 93篇 |
1989年 | 80篇 |
1988年 | 65篇 |
1987年 | 38篇 |
1986年 | 14篇 |
1985年 | 20篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Applied Intelligence - Multi-view data widely exists in real life, which contains rich and comprehensive information. Multi-view learning aims to make full use of the information of multiple views... 相似文献
162.
163.
Fabrication of Fe3O4 Dots Embedded in 3D Honeycomb‐Like Carbon Based on Metallo–Organic Molecule with Superior Lithium Storage Performance 下载免费PDF全文
Chengfei Li Liuqing Li Zhaopeng Li Weihao Zhong Zhenghui Li Xiaoqing Yang Guoqing Zhang Haiyan Zhang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(38)
A novel metallo–organic molecule, ferrocene, is selected as building block to construct Fe3O4 dots embedded in 3D honeycomb‐like carbon (Fe3O4 dots/3DHC) by using SiO2 nanospheres as template. Unlike previously used inorganic Fe3O4 sources, ferrocene simultaneously contains organic cyclopentadienyl groups and inorganic Fe atoms, which can be converted to carbon and Fe3O4, respectively. Atomic‐scale Fe distribution in started building block leads to the formation of ultrasmall Fe3O4 dots (≈3 nm). In addition, by well controlling the feed amount of ferrocene, Fe3O4 dots/3DHC with well‐defined honeycomb‐like meso/macropore structure and ultrathin carbon wall can be obtained. Owing to unique structural features, Fe3O4 dots/3DHC presents impressive lithium storage performance. The initial discharge and reversible capacities can reach 2047 and 1280 mAh g?1 at 0.05 A g?1. With increasing the current density to 1 and 3 A g?1, remarkable capacities of 963 and 731 mAh g?1 remain. Moreover, Fe3O4 dots/3DHC also has superior cycling stability, after a long‐term charge/discharge for 200 times, a high capacity of 1082 mAh g?1 can be maintained (80% against the capacity of the 2nd cycle). 相似文献
164.
Polynomial interpolations, one of the most common interpolations used in finite element methods (FEMs), are a workhorse of many FEM codes. These interpolations are readily available for all kinds of elements, and using them for modeling the variation of elastic moduli in graded elements is thus both convenient and natural. Yet, like all polynomial interpolations, they can be prone to oscillations that can result in regions of negative elastic modulus in the element, even with only positive nodal values of elastic moduli. The result of these negative modulus regions, even if the region is small, can be unexpected singularities in the solution. This defeats the purpose of using polynomial interpolations for capturing material grading in the element. We demonstrate the issue using three-node quadratic Lagrange interpolations of material grading in otherwise isoparametric p-type elements and show how to avoid this problem. 相似文献
165.
In this paper, a supply chain system is viewed as a maintainable system, and the economic-statistical design of a likelihood ratio control chart with a maintenance application is considered for this system. The supply chain system is described by a three-state: normal state, warning state and failure state. A likelihood ratio control chart is used to monitor the system given that only categorical observations can be obtained. When the chart signals, a full inspection is performed to determine the actual system state (normal or warning), and preventive maintenance is immediately performed in the warning state. In addition, the supply chain system must be corrected upon failure (i.e. corrective maintenance), and should be maintained in a scheduled time (i.e. planned maintenance). A mathematical model is developed for the joint optimisation of the control chart parameters and planned maintenance time based on renewal theory. An example is presented to illustrate how to determine the optimal design parameters. We also investigate the effect of coefficients and statistical constraints on the decision variables and the expected cost. 相似文献
166.
167.
168.
Efficient and Targeted Suppression of Human Lung Tumor Xenografts in Mice with Methotrexate Sodium Encapsulated in All‐Function‐in‐One Chimeric Polymersomes 下载免费PDF全文
169.
170.