全文获取类型
收费全文 | 1017篇 |
免费 | 60篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 11篇 |
综合类 | 4篇 |
化学工业 | 474篇 |
金属工艺 | 17篇 |
机械仪表 | 27篇 |
建筑科学 | 31篇 |
矿业工程 | 4篇 |
能源动力 | 28篇 |
轻工业 | 65篇 |
水利工程 | 6篇 |
石油天然气 | 12篇 |
武器工业 | 2篇 |
无线电 | 29篇 |
一般工业技术 | 220篇 |
冶金工业 | 62篇 |
原子能技术 | 9篇 |
自动化技术 | 81篇 |
出版年
2023年 | 5篇 |
2022年 | 96篇 |
2021年 | 100篇 |
2020年 | 34篇 |
2019年 | 26篇 |
2018年 | 48篇 |
2017年 | 43篇 |
2016年 | 44篇 |
2015年 | 26篇 |
2014年 | 41篇 |
2013年 | 62篇 |
2012年 | 58篇 |
2011年 | 77篇 |
2010年 | 42篇 |
2009年 | 54篇 |
2008年 | 49篇 |
2007年 | 33篇 |
2006年 | 24篇 |
2005年 | 33篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 33篇 |
2001年 | 19篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有1082条查询结果,搜索用时 632 毫秒
1.
2.
Konstantin V. Dergilev Evgeny K. Shevchenko Zoya I. Tsokolaeva Irina B. Beloglazova Ekaterina S. Zubkova Maria A. Boldyreva Mikhail Yu. Menshikov Elizaveta I. Ratner Dmitry Penkov Yelena V. Parfyonova 《International journal of molecular sciences》2020,21(24)
Cell therapy of the post-infarcted myocardium is still far from clinical use. Poor survival of transplanted cells, insufficient regeneration, and replacement of the damaged tissue limit the potential of currently available cell-based techniques. In this study, we generated a multilayered construct from adipose-derived mesenchymal stromal cells (MSCs) modified to secrete stem cell factor, SCF. In a rat model of myocardium infarction, we show that transplantation of SCF producing cell sheet induced activation of the epicardium and promoted the accumulation of c-kit positive cells in ischemic muscle. Morphometry showed the reduction of infarct size (16%) and a left ventricle expansion index (0.12) in the treatment group compared to controls (24–28%; 0.17–0.32). The ratio of viable myocardium was more than 1.5-fold higher, reaching 49% compared to the control (28%) or unmodified cell sheet group (30%). Finally, by day 30 after myocardium infarction, SCF-producing cell sheet transplantation increased left ventricle ejection fraction from 37% in the control sham-operated group to 53%. Our results suggest that, combining the genetic modification of MSCs and their assembly into a multilayered construct, we can provide prolonged pleiotropic effects to the damaged heart, induce endogenous regenerative processes, and improve cardiac function. 相似文献
3.
Felix Rivkin Irina Kuznetsova Nadezhda Ivanova Sergey Suhodolsky 《Soil Mechanics and Foundation Engineering》2002,39(1):42-43
Soil Mechanics and Foundation Engineering - 相似文献
4.
Borodina I. A. Zaitsev B. D. Kuznetsova I. E. Teplykh A. A. Shurygin V. V. 《Technical Physics Letters》2003,29(9):781-783
The conditions for hybridization of the zero-order and high-order acoustic waves propagating in a piezoelectric crystal plate have been studied. The dependence of the phase velocity of the hybrid waves on the parameter hf (h is the plate thickness and f is the wave frequency) is established for the potassium niobate and lithium niobate plates possessing various crystallographic orientations and conductivities. It is found that hybridization takes place when the conductivity of a thin surface layer exceeds a certain critical value, which can vary within broad limits depending on the plate material and orientation. The degree of dispersive repulsion of the coupled modes grows with increasing electromechanical coupling coefficient. 相似文献
5.
The standard impact factor as an evaluation tool of science fields and scientific journals 总被引:2,自引:2,他引:0
Irina Marshakova-Shaikevich 《Scientometrics》1996,35(2):283-290
The standard impact factor for particular fields of science (Ig) and the relative impact factor K for scientific journals are introduced. The technique of calculation of standard impact factor (Ig) for a field is an inherent part of a method which allows a cross-field evaluation of scientific journals. This method for evaluating scientific journals elaborated in 1988 was aimed at the analysis of Russian journals covered by the SCI database, it was also used for chemical journals (more that 300) and for journals in the Life sciences (more than 1000). The results are discussed. 相似文献
6.
Quantum-mechanical reaction rate constants were calculated from centroid molecular dynamics (CMD) simulations, for the case of barrier crossing in an asymmetrical double-well potential bilinearly coupled to a harmonic bath. The calculation is based on a recently proposed formulation of the reaction rate constant in terms of the position—flux correlation function, which can be approximated via CMD in a well-defined manner. The predictions of CMD and various simplified versions of it are compared to exact results, which were obtained via the quasi-adiabatic propagator path integral (QUAPI) method, and/or path integral quantum transition state theory (PI-QTST). The predictions based on CMD are found to be in good agreement with both. 相似文献
7.
Irina Naydenova Torleiv Klove 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(3):1188-1193
Bose and Lin introduced a class of systematic codes for detection of binary asymmetric errors. In this note, we describe a generalization to q-ary asymmetric error detecting codes. For these codes, the possible undetectable errors are characterized and the undetectable errors of minimum weight are determined 相似文献
8.
9.
V.V. Milyavskiy T.I. Borodina S.N. Sokolov A.Z. Zhuk 《Diamond and Related Materials》2005,14(11-12):1924
Shock-induced phase transitions of C70 fullerite were studied at the pressure range up to 52 GPa with use of recovery assemblies of planar geometry. The starting material consists of two crystalline phases: phase with hexagonal close-packed (HCP) and phase with rhombohedral structure. We have found that C70 fullerite undergoes a series of polymorphic phase transitions in conditions of step-like shock-wave compression. In the specimens, recovered from 9, 14 and 19 GPa, a dominant phase was fullerite C70 with cubic structure. Also, some amount of C70 with HCP structure was observed. The quantity of HCP phase was decreasing with increasing of intensity of shock loading. With further growth of shock pressure, destruction of C70 molecules occurs. In the samples, recovered after shock loading, the main phase was graphite with a low degree of three-dimensional regularity. 相似文献
10.
Rami Dana Irina Kiruschev Phong Dinh Tran Pascal Doppelt Yishay Manassen 《Israel journal of chemistry》2008,48(2):87-97
A new design for a dual-tip scanning tunneling microscope (STM) is presented. The design is a variation on the mechanically controllable break-junction with two electron beam-induced deposition nano-tips. The new design enables one to scan surfaces simultaneously with two probes having a nano-gap separation. By collecting the lateral current flowing between the tips, the transconductance map can then be compared with the STM images for local characterizations of the electron transport. Since the lateral beam carries the property of the density of states of the surface at momentum space, the dispersion of the electronic structure should give an orientation and position dependence of the local transconductance current. In addition, the reduced terminal separation, on the order of the characteristic mesoscopic length scales, is likely to be sensitive to a variety of typically observed interactions and interference effects. 相似文献