全文获取类型
收费全文 | 1188篇 |
免费 | 23篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 84篇 |
化学工业 | 271篇 |
金属工艺 | 44篇 |
机械仪表 | 15篇 |
建筑科学 | 23篇 |
能源动力 | 58篇 |
轻工业 | 116篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 83篇 |
一般工业技术 | 224篇 |
冶金工业 | 169篇 |
原子能技术 | 55篇 |
自动化技术 | 67篇 |
出版年
2023年 | 3篇 |
2022年 | 18篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 22篇 |
2018年 | 30篇 |
2017年 | 19篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 32篇 |
2013年 | 60篇 |
2012年 | 48篇 |
2011年 | 51篇 |
2010年 | 39篇 |
2009年 | 51篇 |
2008年 | 61篇 |
2007年 | 57篇 |
2006年 | 38篇 |
2005年 | 45篇 |
2004年 | 43篇 |
2003年 | 43篇 |
2002年 | 31篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 34篇 |
1998年 | 66篇 |
1997年 | 51篇 |
1996年 | 37篇 |
1995年 | 31篇 |
1994年 | 33篇 |
1993年 | 27篇 |
1992年 | 17篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有1215条查询结果,搜索用时 15 毫秒
151.
Nakamichi Yamasaki Inna R. Korablova Sergiy F. Korablov 《Journal of the American Ceramic Society》2003,86(6):1061-1063
Formation of an amorphous Al2 Si2 O5 layer on a steel pipe surface, after granite–dry steam interaction in the presence of copper, has been determined by XRD analysis and SEM (with energy dispersive X-ray microanalysis). Kinetic data indicate high-protective properties of the Al2 Si2 O5 layer, which formed a three-dimension substrate ∼5 μm thick, after 100 h exposure. 相似文献
152.
H Ohba M Nishikawa M Kimura N Yamasaki S Moriwaki K Itoh 《Canadian Metallurgical Quarterly》1998,62(6):1166-1170
A prospective study of activated protein C sensitivity, protein C, protein S, and other coagulation factors in 239 women during normal pregnancy was carried out. Protein C activity appeared unaffected by gestation, although an elevation of protein C activity was observed in the early puerperium. A fall in total and free protein S with increasing gestation was observed. Activated protein C sensitivity ratio (APC:SR) showed a progressive fall through pregnancy. This fall correlated with changes in factor VIIIc, factor Vc and protein S. 38% of subjects, with no evidence of Factor V Leiden or anticardiolipin antibodies, showed a low APC:SR (APC:SR <2.6) in the third trimester of pregnancy. Aside from a significant reduction in birth weight, no difference in pregnancy outcome was observed between these subjects and those with a normal APC:SR. Activated protein C sensitivity ratio, modified by pre-dilution of patient samples with factor V depleted plasma, showed no consistent trend with gestation. 相似文献
153.
J Yamaoka S Yamasaki H Kurazono S Imamura M Noda K Miyai Y Takeda 《Canadian Metallurgical Quarterly》1997,23(5):297-302
PURPOSE: To determine the maximum tolerated dose, toxicities, and potential antitumor activity of edatrexate (E), an antifolate agent with enhanced in vitro antitumor activity as compared with methotrexate (M), when given in combination with vinblastine, doxorubicin, cisplatin, and filgrastim (G-CSF) to patients with advanced malignancies. PATIENTS AND METHODS: Thirty-seven patients with advanced malignancies were treated with escalating doses of edatrexate in combination with vinblastine (V), doxorubicin (A), cisplatin (C), and filgrastim (EVAC/G-CSF) following three different subsequently developed schedules. Schedule 1 was patterned after the MVAC regimen, a combination chemotherapy program with activity against different epithelial malignancies, and consisted of E, 40 mg/m2/day, days 1/15/22; V, 3 mg/m2/day, days 2/15/22; A, 30 mg/m2/ day, day 2; C, 70 mg/m2/day, day 2; repeated every 28 days. Schedules 2 and 3 were designed to avoid observed dose-limiting toxicity on schedule 1 consisting of transient elevation of serum creatinine levels and delayed myelosuppression. Schedule 2 consisted of E, 40 or 60 mg/ m2/day, days 1 and 15; V, 3 mg/m2/day, days 2 and 15; A, 30 mg/m2/day, day 2; C, 30 mg/m2/day, days 1 and 2; cycled every 28 days. Schedule 3 consisted of E, 60 to 120 mg/m2/day, day 1; V, 3 mg/m2/day, day 2; A, 30 mg/m2/day, day 2; C, 30 mg/m2/day, days 1 and 2; cycled every 21 days. Filgrastim 5 micrograms/kg/day was given to all patients subcutaneously until the absolute neutrophil count was greater than 10,000/microL postnadir. Three patients were treated on schedule 1, 10 on schedule 2 (four at an E dose of 40 mg/m2/day and six at an E dose of 60 mg/m2/day), and 24 on schedule 3 (six at each of the following E dosages: 60, 80, 100, and 120 mg/m2/day). RESULTS: Dose-limiting toxicities of grade 3 to 4 leukopenia and transient elevation of serum creatinine values were observed in two of three patients treated on schedule 1. A dose-limiting toxicity of grade 3 to 4 leukopenia was noted in two of six patients treated on schedule 2 at an edatrexate dose of 60 mg/m2/day. Two of six patients treated on schedule 3 at an edatrexate dose of 120 mg/m2/day had a dose-limiting toxicity of grade 3 stomatitis (one patient) and grade 3 cytopenia (one patient). Nineteen of 37 patients with evaluable or measurable disease had a response to treatment (response rate 51%, 95% confidence intervals = 35%-67%). Nine of 15 patients with metastatic non-small cell lung cancer responded, including one complete remission (response rate 60%, confidence intervals = 35%-85%). A median survival of 517 days (confidence interval = 163-808 days) and a 1-year survival rate of 60% (confidence interval = 35%-85%) was seen in patients with advanced non-small cell lung cancer. CONCLUSIONS: The maximum tolerated dose and the recommended phase II dose of edatrexate is 100 mg/m2/day when administered as part of the EVAC/G-CSF program following schedule 3. Promising antineoplastic activity against non-small cell lung carcinomas was observed, and a phase II study is planned. 相似文献
154.
The Konan groundwater basin of Kochi Prefecture, Japan, is experiencing freshwater shortages for the past few years, particularly during the winter season. The present study aimed at analyzing the problem and exploring increased groundwater withdrawals to meet burgeoning freshwater demands in various sectors. The trend analysis of waterconsumption indicates that the groundwater demandwould increase by 43 and 52% by the years 2010 and2025, respectively, compared to 32 100 m3 d-1 at present.The streamflow of the Monobe River reduces to a minimumin winter and it shows a decreasing trend in recentyears. The geologic investigation results indicatethat unconfined (phreatic) aquifers comprisingalluvial sand and gravel and/or diluvial silty sandand gravel are dominant, and that the northwestern andwestern portions of the basin have greater potentialfor groundwater. Groundwater flows essentially fromnorth to south into the ocean. Groundwater levelfluctuations over the basin vary appreciably in spaceand time, indicating a wide variation of naturalrecharge. Field observations confirm the hypothesisthat stream-aquifer interaction also significantlycontributes to groundwater recharge, besides therainfall infiltration. Further, the pumping testsresults demonstrate that though the aquifers arelow-yielding, enhanced groundwater withdrawals couldbe possible. The aquifer hydraulic conductivity ischaracterized as high and ranges from 65 to 804 m d-1(mean = 229 m d-1), thereby suggesting great aquiferheterogeneity. Finally, it is concluded that thelong-term sustainability of the scarce groundwaterresource of the Konan basin is doubtful, and that acomprehensive analysis of the groundwater system isessential prior to formulating plans for the futuregroundwater development and management. 相似文献
155.
A Ouhtit M Ueda H Nakazawa M Ichihashi N Dumaz A Sarasin H Yamasaki 《Canadian Metallurgical Quarterly》1997,6(6):433-438
The production and evaluation of non-radioactive probes for the detection of 'Candidatus Liberobacter asiaticum' and 'Candidatus Liberobacter africanum', the two bacterial species associated with citrus huanglongbing (greening) disease is described. Two DNA fagments, In 2.6 and AS 1.7, obtained previously from the beta operons of 'Candidatus Liberobacter asiaticum' and 'Candidatus Liberobacter africanum', respectively, were the starting materials for production of the two non-radioactive probes. These digoxigenin (DIG)-labelled probes were generated by PCR incorporation of DIG-11-dUTP, yielding In 1.7-DIG and AS 1.7-DIG. Probe In 1.7-DIG was hybridized with DNAs extracted from 24 field-collected samples in Bali (Indonesia). The membrane on which the DNAs were blotted was first hybridized with radioactive probe 32P-In 2.6. After the hybridization results were recorded, the radioactive probe was removed, and the membrane hybridized with DIG-labelled probe In 1.7-DIG. Identical results were obtained for 23 samples. One sample was positive with the DIG-labelled probe and negative with the 32P-labelled probe. However, cross-hybridization of In 1.7-DIG with DNA from L. africanum was higher than that obtained with the radioactive probe. This cross-hybridization could be eliminated by raising the temperature of the stringent washing step. No field samples from Africa being available, probe AS 1.7-DIG was dot-blot hybridized against DNAs extracted from leaves of greenhouse-kept citrus plants from different geographical origins and infected with one or other Liberobacter species. The data showed that AS 1.7-DIG hybridized with L. africanum with a sensitivity equivalent to that of the radioactive probe. 相似文献
156.
In this paper we consider nonlinear, infinite networks of purely resistive type where the voltage across a branch of the network is proportional to a fixed power of the current flowing in the branch. It is known that the study of currents in such networks amounts to studying the space of the functions on a network which have finite Dirichlet sums of orderp. Such a study was carried out in [7], [9], and [11]–[14] under the assumption that every node is connected to only finitely many different nodes of the network. In this paper we drop this assumption and work with general countable networks. We prove that most results of the locally finite case, and especially the classification theory, hold true in a more general context. Moreover, we give necessary and sufficient conditions for a network to have only constant Dirichlet finitep-harmonic functions. The relationship with discrete Markov processes is also pointed out. 相似文献
157.
M Yamasaki N Konishi K Yamaguchi S Itoh Y Yokoo 《Canadian Metallurgical Quarterly》1998,62(8):1528-1534
Various derivatives of recombinant human granulocyte colony-stimulating factor (rhG-CSF) have been overproduced in Escherichia coli with the strong, inducible trp promoter. A derivative designated as KW-2228 in which the amino acids were replaced at five positions showed more potent granulopoietic activity and stability than those of wild-type both in vitro and in vivo. The purification involved a sequential renaturation process and three-step chromatography. Refolding succeeded in very high yield using a urea system. The purity of KW-2228 was greater than 99% as measured by SDS-PAGE and HPLC analysis. According to circular dichroism and nuclear magnetic resonance spectroscopy, rhG-CSF and KW-2228 have very similar conformations. This suggests that the substitution of five amino acids does not appreciably change the conformation of hG-CSF. KW-2228 ([Ala1, Thr3, Tyr4, Arg5, and Ser17]-hG-CSF) and derivative A ([Ala1, Thr3, Tyr4, Arg5]-hG-CSF) are easily crystallized and they show similar in vitro activity. On the other hand, neither rhG-CSF nor derivative B ([Ser17]-hG-CSF) are crystallized under the same conditions. Thus, the four amino acid substitution (Ala1, Thr3, Tyr4, Arg5) of the N-terminal sequence may facilitate crystallization. The change of Cys17 to Ser may not influence the stability and activity of hG-CSF. 相似文献
158.
159.
K Sato YH Guo J Feng S Sugiyama M Ichinomiya Y Tsukamasa Y Minegishi A Sakata K Komiya Y Yamasaki Y Nakamura K Ohtsuki M Kawabata 《Canadian Metallurgical Quarterly》1998,811(1-2):69-76
Goldfish were classically conditioned to a mixture of two pulse trains differing in both repetition rate and the spectral profile of the pulses. Animals were then tested for generalization to single pulse trains having one or the other spectral profile presented at a variety of repetition rates. Generalization functions of repetition rate were qualitatively similar to those obtained following conditioning to either of the pulse trains alone. Thus, the spectral profile of each pulse type was appropriately associated with the repetition rate at which that pulse type was presented during conditioning. These results indicate that the two concurrent pulse trains making up the conditioning stimuli were analyzed independently, forming two auditory streams. When either of the two pulse trains were presented with a 500 ms onset asynchrony, stream segregation was enhanced. These and other results suggest that many fundamental features of the human sense of hearing are widely shared among vertebrate animals, and may have developed first among fishes. 相似文献
160.
Plasma-deposited polycrystalline Si films [or microcrystalline Si (μc-Si) films] produced by plasma enhanced chemical vapor deposition (PECVD) have attracted considerable attention as novel, low-cost and stable materials for the photovoltaic i-layer in p–i–n junction thin-film solar cells. The μc-Si films prepared under various deposition conditions show widely various microstructures, from a crystalline–amorphous mixed state to an almost perfect crystalline state, with different crystallographic orientations. These structural changes directly influence the carrier transport properties that play a dominant role in determining photovoltaic performance. Furthermore, obtaining a uniform built-in electric field throughout the i-layer is a crucial issue for achieving excellent photovoltaic performance. To obtain a uniform electric field, the following terms should be required for the i-layer: ‘truly’ intrinsic characteristic (or not n-type characteristics) as well as structural uniformity in the growth direction without an incubation layer. Here, structural properties of μc-Si for achieving truly intrinsic characteristics are reviewed with an emphasis on collations with the crystalline volume function and the degree of (2 2 0) crystallographic preferential orientation in the crystalline phase. In addition, we reviewed a growth mechanism for the μc-Si film that is actually used in the photovoltaic i-layer in highly efficient solar cells: hybrid-phase growth consisting of conventional vapor-phase growth at the surface and the solid-phase crystallization that simultaneously occurs in the film. That growth is very effective in producing structural uniformity along the growth direction and for formation of crystallites directly on the underlying doped layer. 相似文献