全文获取类型
收费全文 | 2381篇 |
免费 | 134篇 |
国内免费 | 31篇 |
专业分类
电工技术 | 31篇 |
综合类 | 26篇 |
化学工业 | 620篇 |
金属工艺 | 49篇 |
机械仪表 | 48篇 |
建筑科学 | 126篇 |
矿业工程 | 23篇 |
能源动力 | 72篇 |
轻工业 | 280篇 |
水利工程 | 20篇 |
石油天然气 | 3篇 |
武器工业 | 2篇 |
无线电 | 188篇 |
一般工业技术 | 415篇 |
冶金工业 | 219篇 |
原子能技术 | 21篇 |
自动化技术 | 403篇 |
出版年
2023年 | 14篇 |
2022年 | 24篇 |
2021年 | 51篇 |
2020年 | 42篇 |
2019年 | 38篇 |
2018年 | 60篇 |
2017年 | 62篇 |
2016年 | 74篇 |
2015年 | 70篇 |
2014年 | 89篇 |
2013年 | 146篇 |
2012年 | 142篇 |
2011年 | 128篇 |
2010年 | 132篇 |
2009年 | 110篇 |
2008年 | 140篇 |
2007年 | 105篇 |
2006年 | 83篇 |
2005年 | 92篇 |
2004年 | 92篇 |
2003年 | 112篇 |
2002年 | 103篇 |
2001年 | 51篇 |
2000年 | 46篇 |
1999年 | 37篇 |
1998年 | 68篇 |
1997年 | 40篇 |
1996年 | 34篇 |
1995年 | 24篇 |
1994年 | 31篇 |
1993年 | 33篇 |
1992年 | 13篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 15篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 15篇 |
1982年 | 20篇 |
1981年 | 10篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 8篇 |
1973年 | 6篇 |
1971年 | 6篇 |
排序方式: 共有2546条查询结果,搜索用时 93 毫秒
1.
Luc Rochette Loubna Mazini Gabriel Malka Marianne Zeller Yves Cottin Catherine Vergely 《International journal of molecular sciences》2020,21(23)
The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs is a major goal in repair medicine. Stem cells are classified by their potential to differentiate into functional cells. Compared with other sources, adipose-derived stem cells (ADSCs) have the advantage of being abundant and easy to obtain. ADSCs are considered to be tools for replacing, repairing, and regenerating dead or damaged cells. The capacity of ADSCs to maintain their properties depends on the balance of complex signals in their microenvironment. Their properties and the associated outcomes are in part regulated by reactive oxygen species, which mediate the oxidation-reduction state of cells as a secondary messenger. ADSC therapy has demonstrated beneficial effects, suggesting that secreted factors may provide protection. There is evidence that ADSCs secrete a number of cytokines, growth factors, and antioxidant factors into their microenvironment, thus regulating intracellular signaling pathways in neighboring cells. In this review, we introduce the roles of ADSCs in the protection of cells by modulating inflammation and immunity, and we develop their potential therapeutic properties. 相似文献
2.
In this article, the authors study the factorial structure of 2 versions (64 items and 32 items) of the Dutch translation of the Inventory of Interpersonal Problems (IIP; L. M. Horowitz, L. E. Alden, J. S. Wiggins, & A. L. Pincus, 2000) in both a clinical sample (n = 382) and a student sample (n = 287). First, the authors test whether both inventories are constituted by correlated uni-dimensional subscales, and they conclude that this is true only for the short version. Second, the authors study whether the correlations between the subscales follow a circumplex pattern. This proves to be true for both versions. Coefficients alpha and correlations between the IIP-64 and IIP-32 subscales are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
A Newman-Tancredi V Audinot C Chaput L Verrièle MJ Millan 《Canadian Metallurgical Quarterly》1997,282(1):181-191
Great progress has been made in the last 10 years in the understanding of the various types of viral hepatitis, and new viruses, concepts, therapies, preventive measures, and control strategies have been recognized. Even more agents, vaccines, and drugs will be discovered or developed in the future, and pediatricians increasingly will be expected to provide guidance to patients and to the community on the importance and use of these new tools. 相似文献
4.
5.
Jean-Louis Iehl Rodolphe Grac Luc le Gratiet Véronique Bardinal Rainer Buhleier Elena Bedel-Pereira Chantal Fontaine Michel Pugnet Jacques-Henry Collet 《电信纪事》1997,52(11-12):627-637
We study the transient gratings photogenerated in the picosecond regime in three families of structures, namely : - structures of thickness in the order of one micron, including quantum wells (GaAs/GaAlAs, CdTe/ CdZnTe). A transmission modulation due to the electric field has been observed. We show that, in accordance with our calculations, this modulation is screened faster than 10 ps at a fluence of a few µJ/cm2. - A structure including GalnAs/GalnAsP MQWS in a cavity. This structure shows a top diffraction efficiency of 2.5 × 10-2 at 1.55 µm for an energy of excitation in the order of 100 µJ/cm2. The diffraction efficiency exhibits several oscillations due to Fabry-Pårot effects. By introducing cavity effects in our model, we show that the diffraction efficiency is amplified by more than a factor 2 with respect to the no-cavity case. Calculations show that the diffraction efficiency may reach 6 × 10-2 around 1.625 µm, for a front mirror reflectivity of 90 %. - Structures including bulk GaAs microcavities. The risetime is lower or in the order of 1 ps while the diffraction efficiency attains 1 %, with an average power of 4 mW (i.e. an energy of 2 µJ/cm2/pulse), compatible with a commutation of packets at 80 MHz. 相似文献
6.
Reviews the book, Psychologie de la famille by Monique V. G. Morval (1985). Morval presents a book with two views: the first looks at the axis of the family in light of systemic approaches and the second centers on the cycle of family life. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Mazzocco Michèle M. M.; Freund Lisa S.; Baumgardner Thomas L.; Forman Lisa; Reiss Allan L. 《Canadian Metallurgical Quarterly》1995,9(4):470
An extensive evaluation was conducted with 16-yr-old monozygotic twins concordant for the fragile X full mutation but discordant for mental retardation. The clearly affected twin had an IQ score of 47; 77% of her neuropsychological z scores were at least 2 SDs below average. Her sister had an IQ score of 105 and average neuropsychological performance. However, each girl demonstrated relative verbal strengths and visual-spatial weaknesses. Their parents rated each girl as having significant problems with attention, conduct, anxiety-withdrawal, and hyperactivity. The girls did not rate themselves as having significant anxiety. These findings are consistent with group data on females with fragile X and demonstrate the wide range of effects associated with the fragile X full mutation. This case report implicates the importance of a psychosocial phenotype of fragile X independent of cognitive ability level. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Control of neuronal morphogenesis by homeoproteins: consequences for the making of neuronal networks
M Volovitch I le Roux AH Joliot E Bloch-Gallego A Prochiantz 《Canadian Metallurgical Quarterly》1993,1(3):133-138
The authors investigated the relationship between plasma lipids and the risk for cortical infarction (61 cases) and transient ischaemic attacks (TIA) (35 cases) compared with matched controls. They observed a maximal increase of total cholesterol, of very low-density lipoprotein and low-density lipoprotein (LDL), triglycerides, total apolipoprotein (Apo), B,LDL-Apo B and Apo-A1, and small size high-density lipoprotein (HDL) and large size HDL whose separation was not possible. In contrast they observed a decrease of HDL-ApoE, a distribution of LDL in a single fraction and the presence of LDL of low weight in the group with cortical infarction with or without cardiac arrhythmias. For the first time, we describe a decrease of the HDL-ApoE/total ApoE ratio. TIA differed from the former group by a low level of HDL and the lack of abnormalities of Apo-A1, distribution of small and large size HDL, and in the distribution and the weight of LDL. These data suggest that previously demonstrated differences in LDL-cholesterol and HDL-cholesterol levels between patients with ischaemic stroke and control subjects may apply to patients with cortical infarction, and that in TIA there are changes in the distribution and the weight of LDL. 相似文献
9.
A computer model was extended and adapted to simulate the hygrothermal behavior of building envelope-wood components. The model was used to predict moisture movement in wood planks forming the decks of nonvented flat roofs insulated with cellulose. The gradient of water potential was considered as the driving force for moisture movement in wood. The model required the determination of convective heat- and mass-transfer coefficients, the sorption curves, the effective water conductivity for different wood species, and the hygrothermal conditions within the assembly to characterize the mass-conservation equation. Once these parameters were integrated in the computer model, this approach was then validated by carrying a simulation of the drying process of wood planks using experimental data from a large-scale test. 相似文献
10.
Vallerand Robert J.; Blais Marc R.; Lacouture Yves; Deci Edward L. 《Canadian Metallurgical Quarterly》1987,19(1):1
Conducted a reliability and validity study of the French version of E. L. Deci and R. M. Ryan's (1985) General Causality Orientations Scale (GCOS), which measures the extent to which people are oriented toward the autonomy, control, and impersonal aspects of the initiation and regulation of behavior. Findings support the psychometric and construct validity of the French version of the GCOS; suggestions for its use in French-Canadian psychological research are discussed. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献