全文获取类型
收费全文 | 1794篇 |
免费 | 34篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 23篇 |
综合类 | 1篇 |
化学工业 | 277篇 |
金属工艺 | 59篇 |
机械仪表 | 27篇 |
建筑科学 | 59篇 |
矿业工程 | 12篇 |
能源动力 | 43篇 |
轻工业 | 92篇 |
水利工程 | 23篇 |
石油天然气 | 1篇 |
无线电 | 149篇 |
一般工业技术 | 245篇 |
冶金工业 | 569篇 |
原子能技术 | 12篇 |
自动化技术 | 238篇 |
出版年
2021年 | 11篇 |
2020年 | 15篇 |
2018年 | 23篇 |
2017年 | 10篇 |
2016年 | 28篇 |
2015年 | 12篇 |
2014年 | 24篇 |
2013年 | 75篇 |
2012年 | 37篇 |
2011年 | 61篇 |
2010年 | 51篇 |
2009年 | 41篇 |
2008年 | 76篇 |
2007年 | 55篇 |
2006年 | 52篇 |
2005年 | 49篇 |
2004年 | 49篇 |
2003年 | 41篇 |
2002年 | 41篇 |
2001年 | 32篇 |
2000年 | 26篇 |
1999年 | 38篇 |
1998年 | 97篇 |
1997年 | 80篇 |
1996年 | 65篇 |
1995年 | 43篇 |
1994年 | 43篇 |
1993年 | 50篇 |
1992年 | 29篇 |
1991年 | 20篇 |
1990年 | 31篇 |
1989年 | 28篇 |
1988年 | 19篇 |
1987年 | 25篇 |
1986年 | 27篇 |
1985年 | 36篇 |
1984年 | 36篇 |
1983年 | 27篇 |
1982年 | 28篇 |
1981年 | 26篇 |
1980年 | 27篇 |
1979年 | 17篇 |
1978年 | 21篇 |
1977年 | 27篇 |
1976年 | 29篇 |
1975年 | 11篇 |
1974年 | 26篇 |
1973年 | 10篇 |
1972年 | 14篇 |
1970年 | 8篇 |
排序方式: 共有1830条查询结果,搜索用时 0 毫秒
1.
The short contact time dissolution of vitrinite and inertinite concentrates of an Australian bituminous coal was studied under isothermal conditions with tetralin as solvent. The reactivity of the two maceral types and the yields and nature of the products were determined for a range of reaction temperatures (400, 420 and 440 °C) and reaction times (2–20 min). The dissolution of vitrinite proceeded at a significantly greater rate than for inertinite and was associated with greater selectivity to soluble non-gaseous products. At very short reaction times (2 min), the vitrinite underwent solubilizing reactions to yield products of higher molecular weight and greater oxygen functionality than was the case for inertinite, for which changes in the chemical nature of the products were negligible over the range of conditions studied. At longer reaction times (5 min), the composition of the vitrinite-derived products was similar to that of the inertinite-derived products. 相似文献
2.
Chwen-Jyh Jeng Warren B. Kindzierski Daniel W. Smith 《Canadian Metallurgical Quarterly》2007,133(3):331-339
This paper presents a particle penetration model predicting particle penetration coefficient (Pp) through a narrow crack of arbitrary incline angles (θ). The objective was to simulate Pp for outdoor-to-indoor particle penetration for residential infiltration conditions. This model assumes laminar infiltration flow and considers particle deposition from both gravitational sedimentation and Brownian diffusion. For micron-sized particles, modeling results indicate that gravitational sedimentation is the major deposition mechanism. Pp increases monotonically with ∣θ∣ because effective particle sedimentation velocity (vs?cos?θ) decreases monotonically with ∣θ∣. For submicron-sized particles (0.1?μm), Brownian diffusion is the major particle deposition mechanism. Because Brownian diffusion is a nondirectional deposition mechanism, crack inclination did not affect Pp. This study applied this model to estimate Pp for L-shaped cracks, and validated modeling results with experiments. Experimental results indicated that inertial impaction and crack entrance cutoff effects were not significant particle deposition mechanisms for the test micron-sized particles. Gravitational sedimentation was the major deposition mechanism. An L-shaped crack can be simulated as the combination of horizontal and vertical sections. This model agreed reasonably with experimental results. 相似文献
3.
4.
J Hellman EM Zanzot PM Loiselle SF Amato KM Black Y Ge JT Kurnick HS Warren 《Canadian Metallurgical Quarterly》1997,176(5):1260-1268
The binding of IgG in antiserum to Escherichia coli J5 to the surface of Enterobacteriaceae and to cell wall fragments released from serum-exposed bacteria was studied in a search for potentially protective epitopes other than lipopolysaccharide (LPS). IgG titers to multiple heterologous gram-negative smooth bacteria increased following incubation of the bacteria in serum and decreased following absorption with serum-exposed heterologous bacteria. IgG eluted from absorbing bacteria bound to at least three conserved bacterial outer membrane proteins (OMPs), but not LPS, as assessed by immunoblotting. The same OMPs were present in LPS-containing macromolecular cell wall fragments released by incubation of heterologous gram-negative bacteria in human serum. Part of the protection offered by J5 antiserum could be from binding of IgG to conserved OMPs at the bacterial surface or to OMPs in cell-wall fragments released from dying bacteria. 相似文献
5.
HS Warren 《Canadian Metallurgical Quarterly》1996,74(5):473-480
Considerable progress has been made in recent years in understanding the biology of NK cells. NK cells are no longer 'null cells', but express an array of functionally important molecules with which they mediate and regulate their cytolytic activity and the cytokines they secrete. Activation and proliferation of NK cells in influenced by cytokines produced by activated monocytes (IL-15, IL-12, IL-10) and activated T cells (IL-2). This paper reviews the phenotype and effector functions of NK cells, their tissue distribution, and evidence that NK cells proliferate in vivo as part of productive or pathologic consequences of immunity. 相似文献
6.
An efficient method is described for sensitivity analysis of nonlinear initial value problems, which may include algebraic equations as well as ordinary differential equations.The linearity of the sensitivity equations is utilized to solve them directly via the local Jacobian of the state equations. The method is implemented with the implicit integrator DASSL and is demonstrated on a stiff industrial reaction model. 相似文献
7.
Free and bound hydrosoluble protein extracts were prepared from four anatomical areas of a multiple sclerosis (MS) cerebrum and from corresponding anatomical areas of a normal (non-MS) control. Increased levels of IgG and anti-myelin basic protein antibodies (anti-MBP) were detected in all MS samples and they were undetectable in the controls. IgG and anti-MBP from free (unbound) hydrosoluble protein extracts are defined as free IgG and free anti-MBP while IgG and anti-MBP from tissue bound protein extracts are defined as bound IgG and bound anti-MBP. IgG was purified from free protein extracts by protein G Sepharose affinity chromatography and anti-MBP was further isolated from purified IgG by antigen specific (MBP) Sepharose affinity chromatography. Free and bound anti-MBP were reacted with 20 synthetic peptides of human MBP prepared by the Fmoc method. Free anti-MBP, whether in the context of whole protein extracts, or as purified IgG or as purified antibody was completely neutralized by peptides #12, #15, #56 and #56* containing overall residues 75-106, partially neutralized by peptides #27, #16 and #21 containing overall residues 61-83 and did not react with the remaining 13 peptides. Tissue bound anti-MBP was completely neutralized only by peptides #12, #15, #56 and #56* (overall residues 75-106) and showed no reactivity towards the remaining 16 peptides including peptides #27, #16 and #21. Synthetic peptide specificity of free anti-MBP purified from MS cerebrum was identical to previously reported specificity of free anti-MBP from MS cerebrospinal fluid (CSF), while tissue bound anti-MBP, as well as bound anti-MBP from CSF had a more restricted synthetic peptide specificity than free anti-MBP. This suggests that the most likely epitope of anti-MBP is located between residues 84 and 95 of human MBP just proximal to the tri-proline sequence (99-101). 相似文献
8.
9.
Cortical implants for the blind 总被引:4,自引:0,他引:4
Arrays of stimulating electrodes can be placed in the brain itself, in the visual cortex, to bring vision to the profoundly blind. However, when designing such devices one needs to take into consideration the fact that the visual pathway maps images onto cortical structures in a complex and unpredictable way 相似文献
10.