全文获取类型
收费全文 | 532篇 |
免费 | 29篇 |
专业分类
电工技术 | 5篇 |
综合类 | 1篇 |
化学工业 | 143篇 |
金属工艺 | 27篇 |
机械仪表 | 23篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 32篇 |
轻工业 | 38篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 62篇 |
一般工业技术 | 76篇 |
冶金工业 | 41篇 |
自动化技术 | 95篇 |
出版年
2023年 | 6篇 |
2022年 | 24篇 |
2021年 | 27篇 |
2020年 | 11篇 |
2019年 | 4篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 10篇 |
2015年 | 20篇 |
2014年 | 19篇 |
2013年 | 39篇 |
2012年 | 40篇 |
2011年 | 40篇 |
2010年 | 26篇 |
2009年 | 30篇 |
2008年 | 23篇 |
2007年 | 9篇 |
2006年 | 18篇 |
2005年 | 23篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 16篇 |
1997年 | 7篇 |
1996年 | 13篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1971年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有561条查询结果,搜索用时 15 毫秒
71.
Infections were a major cause of death in 84% of 38 autopsied renal allograft recipients in a south Indian hospital. Pyogenic bacteria and fungi were the most common etiological agents encountered, being present in 50 and 47% of cases, respectively. Tuberculosis and hepatitis B virus infection were more prevalent and Pneumocystis carinii and cytomegalovirus disease rarer than in comparable series from non-tropical countries. 1 case each of amoebiasis, strongyloidiasis and filariasis were the parasitic infections encountered. 相似文献
72.
The operation of zero-voltage-switching multi-resonant power converters (ZVSMRCs) limits the use of peak current-mode control. The charge control technique is found applicable to ZVSMRCs for improving dynamic performance. Charge control compares the total charge of the switch current to the control voltage to modulate the switching frequency. Since the charge of the switch current of the forward ZVSMRCs is proportional to the input voltage, charge control provides a fast inner loop and offers excellent transient response. Charge control also provides the possibility to achieve current sharing for ZVSMRC parallel applications 相似文献
73.
74.
The study of feedback fractional-order systems has been receiving considerable attention due to the facts that many physical systems are well characterized by fractional-order models, and that fractional-order controllers are used in feedback systems with the intention of breaking through the performance limitation of integer-order controllers. Owing to the lack of effective analytic methods for the time-domain analysis and simulation of linear feedback fractional-order systems, we suggest in this paper two reliable and accurate numerical methods for inverting fractional-order Laplace transforms. One is based on computing Bromwich's integral with a numerical integration scheme capable of accuracy control, and the other is based on expanding the time response function in a B-spline series. In order to demonstrate the superiority in solution accuracy and computational complexity of these two numerical methods over the Grunwald-Letniknov approximation method and Podlubny's analytic formulas, which are in a form of double infinite series, the time-domain simulations of the feedback control of a fractional-order process with a PDμ-controller and a fractional-order band-limited lead compensator are worked out. The simulation results indicate that a convergence problem indeed occurs in using Podlubny's infinite series expressions, and that the problem could not be overcome by a series acceleration scheme 相似文献
75.
The increased need for accurate and repeatable impurity profiling of shallow junction devices places stringent requirements on the profiling procedures and subsequent data reduction. A computer algorithm is described which simplifies the conversion of sheet resistance to impurity profile as required by the anodization and stripping technique. Error magnification commonly found in discrete data differentiation is avoided. Empirical mobility vs carrier concentration expressions are derived from several sources, and a self-contained computer algorithm is given which allows for data reduction on commonly available minicomputers using Fortran. The experimenter is provided with a check on the accuracy of the profile information. 相似文献
76.
Joseph Leu 《软件工程师》2005,(9):55-56
TheongoingabilityofS iliconV alleyto generate in novations, grow th, goodjobsand risingincom e hasledm uch ofthew orldtoseektodefineandreplicateitskeyelem ents.S ilicon V alley is not just aone-tim e-onlyphe nom enon.A llthelessonsderivedfrom its experiencem aybeappliedatothertim es,inotherplacesto som e extend. T he fact that m ayors,governors,andotherofficialsfrom alloverthew orldflocktoS antaC laraC ounty,then return hom e to nick nam e theiraspiringhigh-technologyarea"S iliconV il-lage"… 相似文献
77.
Chia‐Hung Lee Leu‐Wei Lo Chung‐Yuan Mou Chung‐Shi Yang 《Advanced functional materials》2008,18(20):3283-3292
We synthesized mesoporous silica nanoparticles (MSN) with different densities of surface positive charges. The positive surface charge was generated by incorporating trimethylammonium (TA) functional groups into the framework of MSN (MSN–TA) via direct co‐condensation of a TA‐silane and tetraethoxysilane (TEOS) in the presence of a base as a catalyst. These MSN–TA samples have well‐defined hexagonal structures with an average particle diameter of 100 nm, pore size of 2.7 nm, and surface area of about 1000 m2 g?1. Anionic drug molecules, Orange II (a fluorescent tracing molecule), and sulfasalazine (an anti‐inflammatory prodrug used for bowel disease), were effectively loaded into these MSN–TA samples and remained inside of the MSN–TA under acidic environment (pH 2–5). The amounts of loading of both Orange II and sulfasalazine were increased with increasing positive charge densities resulting from the increasing number of TA groups. When these drug‐loaded MSN–TA nanoparticles were placed in physiological buffer solution (pH 7.4), a partial negative surface charge on the MSN–TA was generated due to the deprotonation of silanol groups, and the strong electrostatic repulsion triggered a sustained release of the loaded molecules. MSN–TA as a nanovehicle for pH‐dependent loading and controllable release of anionic drug molecules can be used as an oral delivery drug systems targeting at intestine. These drugs can be remained trapped in the nanovehicle when passing through the stomach's acidic environment and be released in intestine where the environmental pH is close to neutral. 相似文献
78.
79.
Julie Pépin Eric Lainé Jean-Claude Grandidier Guillaume Benoit David Mellier Mathilde Weber Christophe Langlois 《International Journal of Hydrogen Energy》2018,43(9):4671-4680
An experimental design based on representative sample is described in order to reproduce the detachment and deformation of the inner polymer layer (called liner) of hyperbaric hydrogen storage vessels during the emptying step. It is the first step of a better understanding of the mechanisms involved in the creation of a liner collapse. Results showed that a hydraulic testing machine fitted with a pressure hydrogen chamber enables to create a liner collapse on small samples by explosive decompression experiments. Tomographic observations have revealed that the collapse appears at the polymer liner/composite interface in areas that are not sufficiently bonded, nor consistently. Determination of liner collapse amplitudes, assessed by tomography, has underlined that, under some specific conditions, the deformation of the liner is permanent even when hydrogen has completely desorbed from the sample. In addition to liner collapses, composite cracks were also highlighted. 相似文献