全文获取类型
收费全文 | 424664篇 |
免费 | 4753篇 |
国内免费 | 1356篇 |
专业分类
电工技术 | 7779篇 |
综合类 | 323篇 |
化学工业 | 63033篇 |
金属工艺 | 18262篇 |
机械仪表 | 13396篇 |
建筑科学 | 9535篇 |
矿业工程 | 2803篇 |
能源动力 | 10891篇 |
轻工业 | 31703篇 |
水利工程 | 4785篇 |
石油天然气 | 9932篇 |
武器工业 | 35篇 |
无线电 | 51376篇 |
一般工业技术 | 87649篇 |
冶金工业 | 76563篇 |
原子能技术 | 10560篇 |
自动化技术 | 32148篇 |
出版年
2021年 | 3895篇 |
2020年 | 2911篇 |
2019年 | 3639篇 |
2018年 | 6366篇 |
2017年 | 6427篇 |
2016年 | 6807篇 |
2015年 | 4100篇 |
2014年 | 7087篇 |
2013年 | 18720篇 |
2012年 | 10929篇 |
2011年 | 14644篇 |
2010年 | 11801篇 |
2009年 | 13336篇 |
2008年 | 13923篇 |
2007年 | 13673篇 |
2006年 | 11911篇 |
2005年 | 10686篇 |
2004年 | 10110篇 |
2003年 | 10246篇 |
2002年 | 9652篇 |
2001年 | 10155篇 |
2000年 | 9426篇 |
1999年 | 9794篇 |
1998年 | 24391篇 |
1997年 | 17074篇 |
1996年 | 13215篇 |
1995年 | 9976篇 |
1994年 | 8831篇 |
1993年 | 8929篇 |
1992年 | 6591篇 |
1991年 | 6460篇 |
1990年 | 6247篇 |
1989年 | 6010篇 |
1988年 | 5953篇 |
1987年 | 5137篇 |
1986年 | 5129篇 |
1985年 | 5607篇 |
1984年 | 5235篇 |
1983年 | 5011篇 |
1982年 | 4580篇 |
1981年 | 4500篇 |
1980年 | 4471篇 |
1979年 | 4346篇 |
1978年 | 4148篇 |
1977年 | 4750篇 |
1976年 | 6053篇 |
1975年 | 3681篇 |
1974年 | 3520篇 |
1973年 | 3581篇 |
1972年 | 3190篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Cresswell M.W. Allen R.A. Guthrie W.F. Sniegowski J.J. Ghoshtagore R.N. Linholm L.W. 《Semiconductor Manufacturing, IEEE Transactions on》1998,11(2):182-193
The physical widths of reference features incorporated into electrical linewidth test structures patterned in films of monocrystalline silicon have been determined from Kelvin voltage measurements. The films in which the test structures are patterned are electrically insulated from the bulk-silicon substrate by a layer of silicon dioxide provided by SIMOX (Separation by the IMplantation of OXygen) processing. The motivation is to facilitate the development of linewidth reference materials for critical-dimension (CD) metrology-instrument calibration. The selection of the (110) orientation of the starting silicon and the orientation of the structures' features relative to the crystal lattice enable a lattice-plane-selective etch to generate reference-feature properties of rectangular cross section and atomically planar sidewalls. These properties are highly desirable for CD applications in which feature widths are certified with nanometer-level uncertainty for use by a diverse range of CD instruments. End applications include the development and calibration of new generations of CD instruments directed at controlling processes for manufacturing devices having sub-quarter-micrometer features 相似文献
62.
The value of flexible videoendoscopy as a biofeedback tool in conservative swallowing rehabilitation of patients suffering from aspiration after head and neck surgery was examined. For this purpose, the outcomes of conventional swallowing therapy and of swallowing therapy with support of videoendoscopic biofeedback were compared. In the first 40 days of swallowing therapy, videoendoscopic biofeedback significantly increased the chance of therapeutic success, shortening the period of functional rehabilitation in comparison to conventional swallowing therapy. Limitations of this visual biofeedback procedure are poor cognitive skills of the patient, rejection of the procedure by the patient and local factors that make the positioning of the endoscope difficult. 相似文献
63.
Pipelining and bypassing in a VLIW processor 总被引:1,自引:0,他引:1
This short note describes issues involved in the bypassing mechanism for a very long instruction word (VLIW) processor and its relation to the pipeline structure of the processor. The authors first describe the pipeline structure of their processor and analyze its performance and compare it to typical RISC-style pipeline structures given the context of a processor with multiple functional units. Next they study the performance effects of various bypassing schemes in terms of their effectiveness in resolving pipeline data hazards and their effect on the processor cycle time 相似文献
64.
65.
66.
Nutrient uptake by the hindlimb was investigated utilising the arteriovenous difference technique in 5 Thoroughbred horses fed to maintenance a diet of 100% roughage or 52% oat grain and 48% roughage. Arterial blood was obtained from a catheter inserted into the carotid artery while venous blood was simultaneously collected from a catheter placed into the iliac vein via the medial saphenous vein. The arteriovenous difference for glucose was significant and represented a mean extraction of 10 +/- 1% with no effect of diet. If fully oxidised, glucose uptake (corrected for lactate and pyruvate arteriovenous difference) was sufficient to account for 78 +/- 13% or 107 +/- 15% of the oxygen consumed by the hindlimb in horses fed a roughage or 52% oat grain diet respectively. Acetate was also a major metabolite of the hindlimb, showing a 39 +/- 5% extraction with no effect of diet. However, the 52% oat grain diet did induce a significant decline in the concentration of acetate in arterial blood. The potential contribution to oxidation in the hindlimb was significantly reduced from 32 +/- 4% in horses fed roughage to 21 +/- 3% when fed 52% oat grain. D-3-Hydroxybutyrate uptake could account for 9 +/- 1% of the oxidation by the hindlimb with no effect of diet. The technique for measuring nutrient uptake across the hindlimb using the arteriovenous difference is relatively simple and would be valuable in investigating fuel use by muscle during exercise. 相似文献
67.
68.
This paper presents a model of heterogenous diffusion in capillary porous materials during the process of drying. The governing heat and mass transfer equations have been established using the liquid as well as vapor flow. Two models have been presented. Model 1 does not consider the heat conduction while the model 2 has been established by considering the conduction. The developed models and the numerical solutions of the resulting differential equations can take into account the moisture and temperature dependent thermophysical properties of the product. All equations have been established in spherical coordinates but the programme written for the purpose of calculations can be used for other geometries also. Numerical calculations have been performed for gas concrete and tiles using model 1, while model 2 has been used for gas concrete only because of the lack of data for thermophysical properties of the tile. For gas concrete it was seen that conduction has only marginal effect on the drying process and the numerical predictions of the drying process were reasonably accurate. 相似文献
69.
Muralidhar N. Ingale Vijaykumar V. Mahajani 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,64(1):80-86
The effectiveness of the hybrid system sonication followed by wet oxidation (SONIWO) to treat otherwise refractory waste has been demonstrated. In such a hybrid system homogeneous CuSO4 catalyst was found to be very efficient. 相似文献
70.
V. A. Arzamastsev N. L. Sardaev A. S. Kochergin 《Metal Science and Heat Treatment》1996,38(11):477-479
The technological process of cold forging applied for the first time in the production of the casing of the internal joint with races is described. The process operations of cold forging and the annealing and carburizing regimes for this part me described. 相似文献