全文获取类型
收费全文 | 1841篇 |
免费 | 78篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 37篇 |
综合类 | 4篇 |
化学工业 | 543篇 |
金属工艺 | 23篇 |
机械仪表 | 21篇 |
建筑科学 | 77篇 |
矿业工程 | 1篇 |
能源动力 | 45篇 |
轻工业 | 199篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 123篇 |
一般工业技术 | 262篇 |
冶金工业 | 334篇 |
原子能技术 | 12篇 |
自动化技术 | 233篇 |
出版年
2023年 | 13篇 |
2022年 | 70篇 |
2021年 | 82篇 |
2020年 | 35篇 |
2019年 | 31篇 |
2018年 | 42篇 |
2017年 | 27篇 |
2016年 | 46篇 |
2015年 | 35篇 |
2014年 | 47篇 |
2013年 | 70篇 |
2012年 | 100篇 |
2011年 | 90篇 |
2010年 | 63篇 |
2009年 | 65篇 |
2008年 | 56篇 |
2007年 | 55篇 |
2006年 | 50篇 |
2005年 | 42篇 |
2004年 | 40篇 |
2003年 | 34篇 |
2002年 | 32篇 |
2001年 | 21篇 |
2000年 | 29篇 |
1999年 | 34篇 |
1998年 | 59篇 |
1997年 | 37篇 |
1996年 | 36篇 |
1995年 | 31篇 |
1994年 | 25篇 |
1993年 | 22篇 |
1992年 | 19篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 18篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1984年 | 13篇 |
1982年 | 14篇 |
1981年 | 20篇 |
1979年 | 21篇 |
1977年 | 17篇 |
1976年 | 17篇 |
1975年 | 13篇 |
1974年 | 18篇 |
1973年 | 20篇 |
1970年 | 17篇 |
1969年 | 22篇 |
1968年 | 17篇 |
1966年 | 22篇 |
排序方式: 共有1920条查询结果,搜索用时 31 毫秒
1.
Homoisoflavonoids (3-benzylidene-4-chromanones) are considered as an infrequent flavonoid class, possessing multi-beneficial bioactivities. The present study gives an overview on phytochemical aspects of homoisoflavonoids, including utilized plant species, parts, extracts, and separation techniques. Overall, these compounds have mainly been isolated and identified from bulbs and rhizomes of the plants belonging to Asparagaceae and Fabaceae families, particularly the genera of Ophiopogon, Dracaena, Scilla, Polygonatum, and Caesalpinia. 相似文献
2.
An effective practical approach that allows not only a significant reduction in the scope of practical experiments in the course of studying suspension separation processes in hydrocyclones, but also makes it possible to assess the intensity of random components of the processes and define the interrelation between such components and hydrodynamics of flows in a hydrocyclone is presented. Within the frames of the developed probabilistic‐statistical model of suspension separation in hydrocyclones on the basis of statistical self‐similarity properties, a relationship was found between determined and random components of the processes. This allowed transitioning from three‐parameter probability density functions for suspension particles in hydrocyclones to two‐parameter functions; thus significantly improving the efficiency of practical application of the developed model. 相似文献
3.
Hannerz Harald; Albertsen Karen; Nielsen Martin Lindhardt; Tüchsen Finn; Burr Hermann 《Canadian Metallurgical Quarterly》2004,23(3):283
This study explored whether factors related to the work environment could predict changes in body mass index (BMI) and whether the effect of psychosocial factors was dependent on baseline BMI. The sample consisted of 1,980 male employees from the Danish National Work Environment Cohort Study. Changes in BMI between 1995 and 2000 were analyzed, by multiple regression, as a function of background variables and a series of occupational variables obtained in 1995. Age, baseline BMI, job insecurity, and psychological demands predicted changes in BMI. Job insecurity and high or low psychological demands increased the likelihood of weight gain among obese employees, whereas they increased the likelihood of weight loss among employees with a low BMI. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
A self‐consistent texture model is implemented in the finite‐element code ABAQUS/Explicit®. Hardening of the slip systems is described by evolution laws for dislocation densities, and the Bauschinger effect is included. With these ingredients the cold rolling of an IF‐steel is simulated and the evolution of texture and anisotropy is examined. The use of the dislocation based hardening law is found to have a significant effect on the evolution of the anisotropic yield surface, but only very little influence on the texture. Furthermore, the hardening model is used to investigate the evolution of dislocation densities in differently oriented grains during plane strain compression. It is found that the dislocation density varies greatly depending on orientation, an observation which can help to explain the orientation dependence of recrystallization. 相似文献
5.
During large scale wildfires, suppression activities are carried out under the direction of an Incident Management Team (IMT). The aim of the research was to increase understanding of decision processes potentially related to IMT effectiveness. An IMT comprises four major functions: Command, Operations, Planning, and Logistics. Four methodologies were used to study IMT processes: computer simulation experiments; analyses of wildfire reports; interviews with IMT members; and cognitive ethnographic studies of IMTs. Three processes were important determinants of IMT effectiveness: information management and cognitive overload; matching component function goals to overall goals; and team metacognition to detect and counter task‐disruptive developments. These processes appear to be complex multi‐person analogues of individual Incident Command processes identified previously. The findings have implications for issues such as: creating IMTs; training IMTs; managing IMTs; and providing decision support to IMTs. 相似文献
6.
7.
Hermann Ney 《Informatik-Spektrum》2003,26(2):94-102
Dieser Beitrag behandlt die Rolle des statistischen Ansatzes in der maschinellen (oder automatischen) Sprachverarbeitung.
相似文献
8.
S Leyvraz M Bacchi T Cerny A Lissoni C Sessa A Bressoud R Hermann 《Canadian Metallurgical Quarterly》1998,9(8):877-884
Ifosfamide and doxorubicin are the most active agents in the treatment of sarcomas and are characterized by a marked dose-response relationship. The objective of this study was to determine the maximum tolerated dose (MTD) of both agents in combination under granulocyte-macrophage colony-stimulating factor (GM-CSF) cover. PATIENTS AND METHODS: Thirty-three patients with untreated sarcomas (soft tissue: n = 20; gynecological: n = 11; bone: n = 2) were treated with ifosfamide 12 g/m2 by continuous i.v. infusion over five days and doxorubicin with dose escalation from 50 mg/m2 i.v. bolus divided on two days, then to 60 mg/m2 bolus divided on three days. Ifosfamide was reduced to 10 g/m2 and doxorubicin was further escalated up to 90 mg/m2. GM-CSF (5 micrograms/kg/day subcutaneously) was started 24 hours after chemotherapy and continued for 10 days. RESULTS: The MTD was reached with the combination of ifosfamide at 12 g/m2 and doxorubicin at 60 mg/m2. But with ifosfamide 10 g/m2 and doxorubicin 90 mg/m2 the MTD was not obtained. While severe leukopenia and granulopenia were observed at all-dose levels, severe anemia was more frequently related to the highest dose of ifosfamide. Severe thrombopenia and mucositis were more commonly observed at the highest dose of doxorubicin. Ifosfamide 10 g/m2 and doxorubicin 90 mg/m2 induced WHO grade 4 leukopenia in 58%, grade 3-4 thrombopenia in 42%, and anemia in 31% of cycles. Mucositis was minor in 50% of cycles. The overall response rate among 31 evaluable patients was 55% (95 confidence interval (CI): 36%-73%), with four (13%) complete responders and 13 (42%) partial responders. Response rates based on soft-tissue sarcomas or gynecological sarcomas alone were similar. Ten patients could be treated by elective surgery and/or radiotherapy. The total group of patients reached a median survival of two years, with 25% (SE 8%) survivors after three years. CONCLUSIONS: The dose level of ifosfamide 10 g/m2 and doxorubicin 90 mg/m2 with supportive GM-CSF is manageable in a multicenter setting and should be further tested in regular phase II trials, including patients with gynecological and soft-tissue sarcomas. Transient toxicity with myelosuppression should be accepted in order to obtain a high antitumor activity of this regimen and a potential improvement in survival. 相似文献
9.
Hermann Knoflacher 《Sadhana》2007,32(4):293-307
Technological determinism has become a kind of religion for many people since it appears to offer solutions for societal problems
as never before in history. Transport is one of the fascinating technology branches developed during the last 200 years. Effortless
movement over long distances has become possible for car users as long as cheap fossil energy is available. However, the effect
of fast transport on urban structures and society was not taken into account when developing these technical means. Technologists
and economists have used indicators for expected benefits of these fast transport modes without taking into account the real
system effects on society and urban structures. Plausible assumptions and hopes instead of scientific understanding of the
complex system are used in practice. In contradiction to widely held beliefs of transportation planners, there is actually
no growth of mobility if counted in number of trips per person per day, no time saving by increasing speed in the system,
and no real freedom of modal choice. Modal choice is dependent on physical and other structures, the artificial environment
built by urban planners, transport experts and political decisions. The core hypothesis of traditional urban and transport
planning ‘growth of mobility’, ‘travel time saving by increasing speed’ and ‘freedom of modal choice’ are myths and do not
exist in the real urban and transport system. This is the reason why urban planning and transport planning based on traditional
non-scientific assumptions is creating continuously not only more transport problems, but also environmental and social as
well as economic problems all over the world, where these principals are applied. Urban transport planning in Europe, understanding
the transport system and the solutions are presented in this paper. 相似文献
10.
Hermann Jahnke 《OR Spectrum》1993,15(1):21-30
Zusammenfassung Eine Lagerzielmengenpolitik für den Fall intermittierender Fertigung mehrerer Sorten auf einer Anlage bei stochastischer Nachfrage wird durch ein Warteschlangenmodell abgebildet. Für die sich ergebenden Kostenfunktion wird eine Approximation vorgeschlagen. Die Bestimmung optimaler Losgrößen und Lagerzielmengen wird untersucht. 相似文献