全文获取类型
收费全文 | 5159篇 |
免费 | 66篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 54篇 |
综合类 | 3篇 |
化学工业 | 493篇 |
金属工艺 | 38篇 |
机械仪表 | 62篇 |
建筑科学 | 105篇 |
矿业工程 | 2篇 |
能源动力 | 48篇 |
轻工业 | 312篇 |
水利工程 | 19篇 |
石油天然气 | 16篇 |
无线电 | 409篇 |
一般工业技术 | 571篇 |
冶金工业 | 2825篇 |
原子能技术 | 20篇 |
自动化技术 | 251篇 |
出版年
2021年 | 38篇 |
2019年 | 22篇 |
2018年 | 30篇 |
2017年 | 36篇 |
2016年 | 27篇 |
2015年 | 29篇 |
2014年 | 44篇 |
2013年 | 144篇 |
2012年 | 75篇 |
2011年 | 116篇 |
2010年 | 82篇 |
2009年 | 76篇 |
2008年 | 91篇 |
2007年 | 103篇 |
2006年 | 97篇 |
2005年 | 88篇 |
2004年 | 83篇 |
2003年 | 92篇 |
2002年 | 82篇 |
2001年 | 77篇 |
2000年 | 91篇 |
1999年 | 125篇 |
1998年 | 834篇 |
1997年 | 501篇 |
1996年 | 341篇 |
1995年 | 210篇 |
1994年 | 165篇 |
1993年 | 199篇 |
1992年 | 71篇 |
1991年 | 63篇 |
1990年 | 73篇 |
1989年 | 78篇 |
1988年 | 85篇 |
1987年 | 67篇 |
1986年 | 68篇 |
1985年 | 64篇 |
1984年 | 29篇 |
1983年 | 39篇 |
1982年 | 45篇 |
1981年 | 58篇 |
1980年 | 47篇 |
1979年 | 32篇 |
1978年 | 31篇 |
1977年 | 112篇 |
1976年 | 171篇 |
1975年 | 26篇 |
1974年 | 20篇 |
1973年 | 17篇 |
1972年 | 18篇 |
1971年 | 13篇 |
排序方式: 共有5228条查询结果,搜索用时 15 毫秒
141.
Hypervolemia with hypertension often occurs 36-72 hours following massive blood and fluid replacement for hypovolemic shock. This syndrome of "fluid overload" has been attributed to the rapid intravascular flux of previously sequestered fluid in patients with impaired diuresis. This hypothesis was tested in 35 injured patients who received a mean of 9.3 L of blood and 17.4 L of salt during resucitation. The renal parameters measured soon after resuscitation included: 1) renal clearance of inulin (GFR), para-amino hippurate (ERPF), milliosmoles, sodium, and free water; 2) inulin space, renal vascular resistance (RVR), O2 consumption, renin, renal blood flow (RBF), and response to furosemide. Eighteen patients developed hypertension, hypervolemia, and respiratory insufficiency. When compared to the 17 normovolemic, non-hypertensive patients, the 18 hypervolemic patients had significantly increased RVR, with a significant decrease in RBF despite an increase in plasma volume and cardiac output. Furosemide produced less diuresis and natriuresis in the hypertensive patients. The balance between hypovolemia and "fluid overload" seemed percarious in the hypertensive patients. Peripheral renin and catecholamine levels were normal in both groups. Patients with post-traumatic "fluid overload" appear to have a combination of hypervolemia, respiratory insufficiency, hypertension, increased cardiac output, decreased extracellular fluid space, and decreased renal perfusion. These findings suggest that decreased interstitial fluid space compliance rather than "fluid overload" is the underlying factor leading to respiratory insufficiency. The therapeutic aspects of these findings are discussed. 相似文献
142.
C. C. Zammit R. E. Hill R. W. Barker 《Journal of Infrared, Millimeter and Terahertz Waves》1982,3(2):189-203
Further measurements of atmospheric emission from a site in the Canary Islands (Izana, âltitude 2.4 km) have been made during the month of August 1980. The measurements were made with a polarising Interferometer and a composite Ge bolometer. An independent measurement of the precipitable water vapour was made using Infrared Hygrometers. The experimental details are described and the spectra obtained are compared with model spectra using the measured precipitable water vapour. 相似文献
143.
The "overnurtured child" is the label applied to adolescent girls whose strong mother-identification and oedipal attachment to father may be associated with a variety of achievement-related conflicts following puberty. Symptoms include anxiety, depression, vague feelings of inadequacy, loneliness, and isolation from peers. These patients suffer from a form of identity diffusion in which pressures to continue achieving at their present rate of excellence collide with pressures to be more "feminine," social, and affiliative. Therapy is conceptualized as a kind of resocialization process aimed at facilitating separation from family and the development of an independent identity. In treatment, the therapist plays a variety of interrelated roles such as role model, family counselor, and teacher. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
144.
Upon further investigation of the recently reported electrocatalytic oxidation of 1,4-cyclohexadiene to benzene by Rh2(TM4)
4
+2
(TM4=2,5-diisocyano-2,5-dimethylhexane), we have obtained data which strongly implicates the 2e– oxidized d7-d7 complex as the electroactive species. This contrasts with the original report which suggested that the le– oxidized d7-d8 radical acted as the key species via hydrogen atom abstraction from 1,4-cyclohexadiene. A possible mechanism for the catalysis is proposed. 相似文献
145.
CE McMahon 《Canadian Metallurgical Quarterly》1976,2(3):112-115
Despite its impressive rate of growth in the past decades, an increasing amount if dissatisfaction with the area of psychosomatic medicine is reflected in recent literature. The discipline's failures relate to concepts of pathogenesis and therapeutic application of research findings. These failures are explained as a necessary consequence of the philosophical tenet of mind-body dualism which underlies medical theory. It is urged that advocates of psychosomatic medicine give the concept of "holism" meaning at the most fundamental level by establishing a rational basis for theory, or else forsake this line of research for others which yield causal relationships conductive to effective therapy. 相似文献
146.
S. Takahashi A. Betancur-Rodiguez S. Hill S. Takasaki J. Yamada H. Anzai 《Journal of Low Temperature Physics》2006,142(3-4):311-314
We report high-resolution angle-dependent measurements of the Periodic Orbit Resonance (POR) effect in (TMTSF)2ClO4. We observe additional harmonic resonances that were not observed in previous studies. By measuring over a broad range of
frequency, field, and field orientation, we find that all of the POR evolve from the Lebed magic angles observed in dc (ω=0)
AMRO measurements. However, we find that the resonance angles vary with frequency in a manner that can easily be explained
using a semiclassical model. This indicates that these angles are not ‘magic’ at frequencies on the order of the cyclotron
frequency. 相似文献
147.
Composite load modeling via measurement approach 总被引:3,自引:0,他引:3
The accuracy of the load model has great effects on power system stability analysis and control. Based on our practice in China on modeling load from field measurements, this paper systematically develops a measurement-based composite load model. Principles guiding the load modeling practice are discussed based on detailed analysis on stochastic characteristics of the modeling procedure. The structure of the measurement-based composite load model is presented. A multicurve identification technique is described to derive parameters. The generalization capability of this built load model is also investigated in this paper. Two cases are studied to illustrate the accuracy of the developed load model on describing the load dynamic characteristics in the actual power system. 相似文献
148.
149.
A novel technique has been developed for the textural analysis of Lambertian surfaces while in the presence of a variable albedo. The method has direct application for the surface quality determination of cosmetically sensitive components, and has particular application where more traditional methods may prove unsatisfactory. A photometric stereo technique is used to facilitate the isolation of localised irregular features, such as scratching, indentations or small protrusions, which may be obscured by a coincident, regular or random surface albedo. A generic lighting arrangement is employed, which obviates the need for a customised lighting configuration. This represents a significant advantage for the configuration of industrial vision-based inspection systems. Promising experimental results have been obtained using example components, and are presented in the paper. 相似文献
150.
The authors address the problem of disturbance attenuation with internal stability via output feedback for a class of passive systems with uncertainties. The problem is approached by means of adaptive output feedback control which does not require any state observer. The results obtained extend an earlier result of Steinberg and Corless (1985). Sufficient conditions are proposed under which a nonlinear system can be made locally or globally passive via output feedback 相似文献