全文获取类型
收费全文 | 775篇 |
免费 | 26篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 53篇 |
化学工业 | 190篇 |
金属工艺 | 9篇 |
机械仪表 | 32篇 |
建筑科学 | 18篇 |
能源动力 | 41篇 |
轻工业 | 73篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 68篇 |
一般工业技术 | 149篇 |
冶金工业 | 78篇 |
原子能技术 | 26篇 |
自动化技术 | 59篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 25篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 24篇 |
2017年 | 12篇 |
2016年 | 23篇 |
2015年 | 15篇 |
2014年 | 27篇 |
2013年 | 64篇 |
2012年 | 38篇 |
2011年 | 47篇 |
2010年 | 40篇 |
2009年 | 38篇 |
2008年 | 43篇 |
2007年 | 30篇 |
2006年 | 30篇 |
2005年 | 29篇 |
2004年 | 24篇 |
2003年 | 24篇 |
2002年 | 21篇 |
2001年 | 6篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 25篇 |
1997年 | 19篇 |
1996年 | 20篇 |
1995年 | 7篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有802条查询结果,搜索用时 31 毫秒
101.
Y Seto M Hashimoto R Usami T Hamamoto T Kudo K Horikoshi 《Canadian Metallurgical Quarterly》1995,59(7):1364-1366
An alkali-sensitive mutant, 18224, of the alkaliphilic Bacillus sp. strain C-125 was characterized. The nucleotide sequence of the PvuI-NlaIV DNA fragment that recovers the alkaliphily of 18224 has been cloned from the mutant and sequenced. Comparison of the nucleotide sequences of the corresponding regions found a G to A substitution in the mutant. The mutation resulted in an amino acid substitution from 82Gly to Glu of the putative ORF3 product, which consisted a gene cluster of at least four tandemly located open reading frames. The ORF3 product was deduced to be an 112 amino acid polypeptide with hydrophobic properties, which was expressed using an in vitro translation system. 相似文献
102.
Takegawa Y Deguchi K Ito S Yoshioka S Nakagawa H Nishimura S 《Analytical chemistry》2005,77(7):2097-2106
Neutral and acidic (sialylated) 2-aminopyridine-derivatized (PA) oligosaccharides were analyzed by using reversed-phase high-performance liquid chromatography/ion trap mass spectrometry (RP-HPLC/IT MS) with a sonic spray ionization (SSI) source. Under the RP-HPLC separation using a buffer of 1 mM ammonium acetate (pH4.3) at a flow rate of 0.2 mL/min, both PA-oligosaccharides in the negative-ion mode showed a comparable degree of ionization efficiency, differing from that of the positive-ion mode, which exhibits a wide gap between their ionization efficiencies. In addition, the ion intensities of both PA-oligosaccharides were higher in the negative-ion mode than in the positive-ion mode. These results strongly suggest that the negative-ion mode of SSI-MS is suitable for simultaneous analysis of neutral and acidic (sialylated) oligosaccharides in RP-HPLC/MS. In the present study, RP-HPLC/SSI-IT MS in the negative-ion mode was used in the analysis of PA-oligosaccharides from human serum and its usefulness was investigated. As a result, 32 neutral and sialylated PA-oligosaccharides from human serum were identified with differentiating isomeric oligosaccharides and relatively quantified by a single HPLC/MS run. This method is useful for simple and rapid analysis of the overall distribution of neutral and sialylated oligosaccharides in a complex sample such as serum. 相似文献
103.
Yasuhiro Awakura Shinya Kamei Hiroshi Majima 《Metallurgical and Materials Transactions B》1980,11(3):377-381
This paper presents the results obtained through a kinetic study of the nonoxidative dissolution of natural galena in hydrochloric
acid and perchloric acid solutions with and without the addition of sodium chloride. Under the experimental conditions employed
in this study, the dissolution rates were controlled by a chemical reaction on the surface of the galena sample. The galena
dissolution rate is of the first order with respect to hydrochloric ion activity in hydrochloric acid and perchloric acid
solutions. The addition of sodium chloride to the acid solutions greatly enhanced the dissolution rate. The effect of sodium
chloride has two possible interpretations: First, it may be the result of an increase in hydrogen ion activity. Second, the
enhancement of the dissolution rate observable at high sodium chloride concentration may be due to the specific adsorption
of chloride ions or the surface complexing of chloride ions on the galena surface. 相似文献
104.
Shinya Otsuka Toyokazu Sano Zensaku Kozuka 《Metallurgical and Materials Transactions B》1980,11(2):313-319
Modified coulometric titrations on the galvanic cell;O in liquid Tl or In/ZrO2(+CaO)/Air, Pt, were performed at 973, 1073, and 1173 K to determine the oxygen activities in liquid thallium and liquid indium.
The standard Gibbs energies of solution of oxygen in liquid thallium and liquid indium for l/2 O2 →O (1 at. pct) were determined respectively to be δG‡(in Tl) = -22000 + 0.74T (±300) cal/g-atom = -92000 + 3.10T (±1300) J/g-atom, δG‡(in In) = -42450+ 3.30T (±350) cal/g-atom = -177600 + 13.8T (±1500) J/g-atom, where the reference state for dissolved oxygen was an infinitely dilute solution. It was reconfirmed that
the apparent initial oxygen concentration observed in the range of very low oxygen concentration in liquid metal was attributed
to the oxygen released from the solid electrolyte. 相似文献
105.
Modified coulometric titrations on the galvanic cell:O in liquid Cu or Ag / ZrO2( + CaO) / Air, Pt, were performed to determine precisely the oxygen activities in liquid copper and silver in the range of
relatively low oxygen concentration. The present experimental results were remarkably reproducible in comparison with the
published data. The standard Gibbs energies of solution of oxygen in liquid copper and liquid silver for 1/2 O2(l atm) → O(l at. pct) were determined respectively to be ΔG° (in Cu) = −18040 −0.03 T(K) (± 120) cal · g-atom−1 = −75500
−0.12 T(K)(± 500) J · g-atom−1, ΔG°(inAg)= -3860+ 1.56 T(K) (±90) cal · g-atom−1 = −16140 + 6.52 T(K)(±380) J · g-atom−1 where
the reference state for dissolved oxygen was an infinitely dilute solution. The present value of the partial entropy of oxygen
dissolved in liquid copper differs significantly from that suggested by many investigators. Further, the present equation
for liquid copper has been found to be consistent with a correlation proposed previously by the present authors. The equation
for liquid silver is in good agreement with the published ones. 相似文献
106.
107.
T Nakaoka N Kojima T Hamamoto N Kurosawa YC Lee H Kawasaki K Suzuki S Tsuji 《Canadian Metallurgical Quarterly》1993,114(4):449-452
A calcium-independent phosphatidylserine specific binding protein detected on liposome blotting analysis was purified from rat brain and revealed to be identical to myristoylated, alanine-rich C kinase substrate (MARCKS). MARCKS specifically binds to phosphatidylserine but not phosphatidylcholine. The binding of MARCKS to phosphatidylserine was abolished on protein kinase C-dependent phosphorylation. Since bacterially expressed MARCKS also specifically binds to phosphatidylserine, myristoylation of the N-terminal glycine seems not to be essential for the binding of MARCKS to phosphatidylserine. These data suggest that phosphatidylserine is a membranous target molecule of MARCKS. 相似文献
108.
109.
Makoto Yamano Shusaku Goto Hideki Hamamoto Vuthy Monyrath 《The Science of the total environment》2009,407(9):3120-560
It is possible to estimate the ground surface temperature (GST) history of the past several hundred years from temperature profiles measured in boreholes because the temporal variation in GST propagates into the subsurface by thermal diffusion. This “geothermal method” of reconstructing GST histories can be applied to studies of thermal environment evolution in urban areas, including the development of “heat islands.” Temperatures in boreholes were logged at 102 sites in Bangkok, Jakarta, Taipei, Seoul and their surrounding areas in 2004 to 2007. The effects of recent surface warming can be recognized in the shapes of most of the obtained temperature profiles. The preliminary results of reconstruction of GST histories through inversion analysis show that GST increased significantly in the last century. Existing temperature profile data for the areas in and around Tokyo and Osaka can also be used to reconstruct GST histories. Because most of these cities are located on alluvial plains in relatively humid areas, it is necessary to use a model with groundwater flow and a layered subsurface structure for reconstruction analysis. Long-term records of subsurface temperatures at multiple depths may demonstrate how the GST variation propagates downward through formations. Time series data provide information on the mechanism of heat transfer (conduction or advection) and the thermal diffusivity. Long-term temperature monitoring has been carried out in a borehole located on the coast of Lake Biwa, Japan. Temperatures at 30 and 40 m below the ground surface were measured for 4 years and 2 years, respectively, with a resolution of 1 mK. The obtained records indicate steady increases at both depths with different rates, which is probably the result of some recent thermal event(s) near the surface. Borehole temperatures have also been monitored at selected sites in Bangkok, Jakarta, and Taiwan. 相似文献
110.
Norio Sakai Hideki Horie Hiromasa Yanagisawa Tadashi Fujii Shinya Mizokami Koji Okamoto 《Journal of Nuclear Science and Technology》2014,51(7-8):951-963
The Modular Accident Analysis Program (MAAP) model enhancement items to improve the simulation capability for molten corium behavior in the accidents at the Fukushima Dai-ichi nuclear power plants were validated with the Phenomena Identification and Ranking Table (PIRT). The importance ranks of the identified phenomena were evaluated for each time phase through brainstorming and discussion with the experts in the Atomic Energy Society of Japan and the members of the MAAP model enhancement project. When the current MAAP evaluation models were reviewed with the PIRT, it is found that 95 of the 386 high-ranked phenomena were not considered in MAAP 5.0.1. While 62 of these phenomena will have been addressed in the MAAP enhancement project and 25 others are not suitable to be analyzed by MAAP, 8 important phenomena should be considered in post-MAAP enhancement project with additional experiments or fundamental studies. 相似文献