全文获取类型
收费全文 | 853篇 |
免费 | 11篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 56篇 |
化学工业 | 107篇 |
金属工艺 | 22篇 |
机械仪表 | 12篇 |
建筑科学 | 24篇 |
能源动力 | 12篇 |
轻工业 | 47篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 158篇 |
一般工业技术 | 135篇 |
冶金工业 | 209篇 |
原子能技术 | 35篇 |
自动化技术 | 47篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 19篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 16篇 |
2011年 | 24篇 |
2010年 | 25篇 |
2009年 | 20篇 |
2008年 | 21篇 |
2007年 | 38篇 |
2006年 | 24篇 |
2005年 | 27篇 |
2004年 | 23篇 |
2003年 | 25篇 |
2002年 | 23篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1999年 | 28篇 |
1998年 | 87篇 |
1997年 | 57篇 |
1996年 | 45篇 |
1995年 | 28篇 |
1994年 | 32篇 |
1993年 | 16篇 |
1992年 | 18篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 19篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 3篇 |
排序方式: 共有866条查询结果,搜索用时 15 毫秒
31.
This is the first report to reveal the particle-water distribution of nitropolycyclic aromatic hydrocarbons (NPAHs) and to discuss their potential risks and utility as indicators of diesel vehicle exhaust particles (DEP). Time-series samples of runoff were collected from a highway, and NPAHs and polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography-mass spectrometry (GC-MS) to study their dynamic behavior. The concentrations of total NPAHs ranged from 11 to 73 ng/L in particulate phase (>0.7 mcirom) and from 2.3 to 4.9 ng/L in dissolved phase (<0.7 microm). Like their PAH analogs, most (81-97%) NPAHs were associated with particulate matter. The organic carbon-normalized in situ partition coefficients (Koc') of NPAHs observed in runoff events (10(5.8-6.3) for 2-nitrofluoranthene and 10(5.8-6.2) for 1-nitropyrene [1-NP]) were more than 1 order of magnitude higher than those expected from their Kow, indicating great affinity for particulate matter such as soot. Concentrations of PAHs and NPAHs adjusted by potency equivalency factors and induction equivalency factors showed that the potential risks of NPAHs were smaller than those of PAHs by a factor of more than a hundred for the particulate phase and morethan fourforthe dissolved phase. Comparison of concentrations and compositions of NPAHs and PAHs among runoff, DEP, gasoline vehicle exhaust particles, boiler exhaust particles, and aerosols suggested that the ratio of 1-NP to total PAHs (1-NP/PAH) is a useful indicator of DEP for source apportionment of PAHs among traffic-related sources. Source-apportionment of PAHs in the runoff by 1-NP/PAH and methylphenanthrene/phenanthrene ratios suggested that most PAHs in the runoff except the second flush peak were derived from DEP but that other pyrogenic sources contributed to the particles at the second flush and thus to the overall runoff particles. 相似文献
32.
T Murai Y Yoshida S Koide K Takada T Misaki N Koshikawa AR Cools 《Canadian Metallurgical Quarterly》1998,60(3):695-701
The spectrum of infectious disease (ID) emergencies in hospitalized patients was assessed in a prospective study of 3,626 inpatient ID consultations in a 1,350-bed teaching hospital. ID emergencies, defined by a need or anticipated need for advanced life support or by irreversible organ damage leading to permanent functional loss, were encountered in 175 patients. Infections of the central nervous system (26.3%), cardiovascular system (14.9%), alimentary system (13.1%), and lower respiratory tract (7.4%) and adverse reactions to antimicrobial agents (7.4%) were most common. In 18.9% of the cases, the referring clinicians were unaware of the emergency at the time of referral. Drug reactions (46.1%), severe alimentary and peritoneal infections (32.0%), upper respiratory tract infections (28.6%), and skin and soft-tissue infections (27.3%) were most frequently missed. The emergency ID conditions were not recognized because they had an atypical presentation (51.5%), were not commonly seen in the referring specialty (24.2%), were due to rare organisms (15.2%), or had unusual anatomical sites of involvement (9.1%). A close liaison between clinicians and the ID team is crucial for recognition of ID emergencies at their early stages so that appropriate investigations and management can be instituted expediently, before the occurrence of irreversible damage. 相似文献
33.
A Rydzewski T Urano N Nagai Y Takada Y Katoh-Oishi T Taminato T Yoshimi A Takada 《Canadian Metallurgical Quarterly》1997,27(6):305-314
The linkage of cobalamin and folate deficiency to psychiatric illness has been studied and debated since these vitamins were first discovered in the 1940s. The clinical relevance of these deficiencies remains the subject of investigation and scholarly discussion. This article reviews case reports and studies derived from a MEDLINE search for English-language articles related to folate, cobalamin, and psychiatric illness. Emphasis is given to clinical research and recent developments. Preclinical evidence for direct effects of folate and cobalamin on brain functioning is compelling, and numerous associations of their deficiencies to psychiatric illness are evident. These vitamin deficiencies may typically present initially with psychiatric symptoms, but any direct causal relationship to specific neuropsychiatric illnesses are not well defined. The relationship of these vitamins in dementia is significant, but they may only rarely be a cause of truly reversible dementia. Folate deficiency appears most tightly connected with depressive disorders, and cobalamin deficiency with psychosis. Contrary to intuition, vitamin deficiencies appear to occur infrequently with eating disorders. Other diagnoses have been investigated much less extensively. The diagnosis and management of these deficiencies in the context of neuropsychiatric illness is still a matter of discussion. The quality of clinical research in this area is improving, but there are many unanswered questions that affect clinical practice. Clinicians should remain vigilant to the possibility of deficiencies of folate and cobalamin in diverse psychiatric populations. Normal hematological indices do not rule out the deficiencies. Further study is needed to refine the detection and clinical management of these vitamin deficiencies in psychiatric populations. 相似文献
34.
Taiji Hamada Seiya Yokoyama Toshiaki Akahane Kei Matsuo Akihide Tanimoto 《International journal of molecular sciences》2023,24(1)
Many variants of uncertain significance (VUS) have been detected in clinical cancer cases using next-generation sequencing-based cancer gene panel analysis. One strategy for the elucidation of VUS is the functional analysis of cultured cancer cell lines that harbor targeted gene variants using genome editing. Genome editing is a powerful tool for creating desired gene alterations in cultured cancer cell lines. However, the efficiency of genome editing varies substantially among cell lines of interest. We performed comparative studies to determine the optimal editing conditions for the introduction of platelet-derived growth factor receptor alpha (PDGFRA) variants in human glioblastoma multiforme (GBM) cell lines. After monitoring the copy numbers of PDGFRA and the expression level of the PDGFRα protein, four GBM cell lines (U-251 MG, KNS-42, SF126, and YKG-1 cells) were selected for the study. To compare the editing efficiency in these GBM cell lines, the modes of clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein 9 (Cas9) delivery (plasmid vs. ribonucleoprotein (RNP)), methods of transfection (lipofection vs. electroporation), and usefulness of cell sorting were then evaluated. Herein, we demonstrated that electroporation-mediated transfer of Cas9 with single-guide RNA (Cas9 RNP complex) could sufficiently edit a target nucleotide substitution, irrespective of cell sorting. As the Cas9 RNP complex method showed a higher editing efficiency than the Cas9 plasmid lipofection method, it was the optimal method for single-nucleotide editing in human GBM cell lines under our experimental conditions. 相似文献
35.
Jun Takada Yoichi Tomii Nobuyuki Yoshida Masahiro Sasaki Masahiro Koiwa 《Oxidation of Metals》1992,37(1-2):13-22
Internal oxidation of dilute silver alloys containing Al, Mg, Zn, Cu, and Sn was studied in air at temperatures between 573 K and 1173 K. Electrical resistivity, gravimetric, and gas-extraction measurements were made. The general trend of the resistivity is that it increases upon oxidation at lower temperatures and the resistivity decreases at higher temperatures in all of these alloys except Ag-Mg, in which it increases even at 1173 K. The increase in resistivity is considered to be related to the formation of clusters having excess oxygen. A detailed investigation was performed on Ag-Al alloys. The O/Al ratio in the clusters in Ag-2.2 at.% Al is much higher on oxidation at 773 K than for stoichiometric Al2O3 at 1173 K. The clusters release the excess oxygen on subsequent annealing at high temperatures, and decompose to stable Al2O3 at 1173 K. 相似文献
36.
Mizutori A. Nishizato Y. Koga M. Mori K. Yamamoto T. Suzuki K. Takada A. 《Electronics letters》2009,45(13):683
A novel optical frequency stabilisation technique on the ITU-T frequency grid employing modulated sideband light is proposed. The L-band laser diode second sideband light generated by phase-modulation is locked to a carbon monoxide 12C16O gas absorption line; the original carrier is placed on the ITU-T frequency grid. The square root of Allan variance of 10-8 has been achieved for a period of 12 h. 相似文献
37.
Yasushi Sekine Haruka Takamatsu Sho Aramaki Kazuki Ichishima Mitsuko Takada Masahiko Matsukata Eiichi Kikuchi 《Applied Catalysis A: General》2009,352(1-2):214-222
The water gas shift (WGS) reaction over Pt and Pd catalysts supported on various perovskite oxides has been investigated at 573 K without catalyst pretreatment. The Pt and Pd catalysts on LaCoO3 support showed high catalytic activity. Interaction between Pt or Pd and the support is considered to promote the WGS reaction: Pt/LaCoO3 had high initial activity but deactivated immediately; Pd/LaCoO3 was less active than Pt/LaCoO3, but had superior stability. Catalysts were characterized using XRD, STEM, XPS, and H2-temperature programmed reduction (TPR). Results of this study showed that reduction of the support decreased the CO conversion on Pt/LaCoO3. On the other hand, Pd/LaCoO3 showed stable activity for the WGS reaction. Therefore, Pd was added to Pt/LaCoO3 for stabilizing the catalyst activity, and 0.5 wt.% Pd/1 wt.% Pt/LaCoO3 catalyst showed higher activity and stability. 相似文献
38.
Takada M Yamaguchi H Kitamura H Uchihori Y Fujitaka K 《Radiation protection dosimetry》2002,99(1-4):391-392
Microdosimetric measurements of 19, 32, 43, 55, and 65 MeV protons were carried out with the A-150-walled low pressure proportional counter (LPPC). The spectra are deconvoluted into three components, which are energy loss by directly incident protons, secondary electrons, and scattered protons and heavy charged particle (including protons) produced by proton nuclear reactions with the TE wall. Dose-mean lineal energies of protons are large as usual, because larger lineal energies by proton reaction events are affected. 相似文献
39.
L-rhamnose isomerase of Pseudomonas sp. LL172 immobilized on BCW 2603 Chitopearl beads was used to produce L-talose and D-gulose. At equilibrium, the production yields of L-talose and D-gulose were determined to be 12 and 10% from L-tagatose and D-sorbose, respectively. The crystallized products were confirmed by HPLC, IR and NMR spectra, and optical rotation measurement analyses. 相似文献
40.
Exposure of gold surfaces to solutions of dithiobis N-succinimidyl propionate (DTSP) gives rise to the modification of the surface with N-succinimidyl-3-thiopropionate (NSTP) which can, in turn, react with amino groups allowing for the covalent immobilization of enzymes such as horseradish peroxidase (HRP). The coverage of NSTP has been estimated to be of the order of 1.3 x 10(-10) from the charge consumed during its reductive desorption. The binding reaction of HRP with NSTP modified gold surfaces has been studied with the quartz crystal microbalance, and the results suggest that the immobilization process involves two steps in which the first (faster) appears to correspond to the rapid incorporation of the enzyme whereas the second is likely due to the slow incorporation of additional enzyme and/or reorganization of the immobilized layer. Spectrophotometric and electrochemical assays indicate that the immobilized HRP retains its enzymatic activity after immobilization onto the DTSP modified gold surface. The amount of immobilized (and active) HRP was estimated from QCM and spectrophotometric measurements to be of the order of 1.5 x 10(-11) mol/cm2. A peroxide biosensor was developed making use of a gold surface modified with DTSP and HRP employing Os and Ru complexes of 1,10-phenanthroline 5,6-dione (phen-dione) of the type [M(phendione)x(L)3-x]+2 (where L = 1,10-phenanthroline or 2,2'-bipyridine, x = 1-3) as mediators with the quinone moieties being the active component. The efficiency of the mediators increased with increasing number of phendione ligands. 相似文献