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排序方式: 共有950条查询结果,搜索用时 15 毫秒
941.
942.
Ahmed Z Shimonishi T Bhuiyan SH Utamura M Takada G Izumori K 《Journal of Bioscience and Bioengineering》1999,88(4):444-448
L-ribose and L-arabinose were prepared biochemically from ribitol via a two-step reaction, by which the complete oxidation of ribitol to L-ribulose (approximately 98%) was achieved by the reaction of washed cells of Acetobacter aceti IFO 3281. The produced L-ribulose was then used as a substrate for the production of L-ribose and L-arabinose. The isomerization of L-ribulose to L-ribose and L-arabinose was carried out using L-ribose isomerase (L-RI) of Acinetobacter sp. strain DL-28 and L-arabinose isomerase (L-AI) of Mycobacterium smegmatis, respectively. At equilibrium, the ratio of L-ribose: L-ribulose was 70:30 and that of L-arabinose: L-ribulose was 90: 10. After a simple purification treatment, both pentoses could be crystallized without the use of column chromatography. The crystals were confirmed as L-ribose and L-arabinose by High-performance liquid chromatography (HPLC), Infrared (IR), Nuclear magnetic resonance (NMR) and optical rotation measurements. 相似文献
943.
Md. Nurul Kabir Bhuiyan Mariela MenghiniJin Won Seo Jean-Pierre Locquet 《Microelectronic Engineering》2011,88(4):423-426
Dy thin films are grown on Ge(0 0 1) substrates by molecular beam deposition at room temperature. Subsequently, the Dy film is annealed at different temperatures for the growth of a Dy-germanide film. Structural, morphological and electrical properties of the Dy-germanide film are investigated by in situ reflection high-energy electron diffraction, and ex situ X-ray diffraction, atomic force microscopy and resistivity measurements. Reflection high-energy electron diffraction patterns and X-ray diffraction spectra show that the room temperature growth of the Dy film is disordered and there is a transition at a temperature of 300-330 °C from a disordered to an epitaxial growth of a Dy-germanide film by solid phase epitaxy. The high quality Dy3Ge5 film crystalline structure is formed and identified as an orthorhombic phase with smooth surface in the annealing temperature range of 330-550 °C. But at a temperature of 600 °C, the smooth surface of the Dy3Ge5 film changes to a rough surface with a lot of pits due to the reactions further. 相似文献
944.
945.
Md. Shahnewaz Bhuiyan Hiroyuki Toda Kazuyuki Shimizu Hang Su Kentaro Uesugi Akihisa Takeuchi Yoshio Watanabe 《Metallurgical and Materials Transactions A》2018,49(11):5368-5381
High-resolution synchrotron X-ray microtomography has been successfully used to evaluate the local crack driving force at arbitrary crack tip locations as a form of CTOD. This is to our knowledge the first experimental evidence in supporting a correlation between the local fracture toughness associated with the corresponding hydrogen-assisted fracture mode including quasi-cleavage, intergranular, and dimple. Our results have revealed that very small CTOD, of about 1.26 μm, is observed when the crack tip is located in the quasi-cleavage fracture. Compared to quasi-cleavage fracture, the CTOD values increase by a factor of 5 when the crack tip is located in intergranular fracture mode and even greater increase in CTOD (of about 18 times) is observed when the crack tip is located in dimple fracture mode. We also observed that the crack propagation process under the influence of hydrogen deviates greatly from that of standard behavior, where stable crack growth is accompanied by a change in crack tip singularity from the HRR to the RDS. It was concluded that the presence of high concentration of hydrogen ahead of the crack tip increases the slip localization, and thereby reduces crack tip blunting. Hence crack continues to grow before the crack tip becomes fully blunt. 相似文献
946.
LB Brydak R Rokicka-Milewska T Jackowska H Rudnicka H Regnery N Cox 《Canadian Metallurgical Quarterly》1997,26(1-2):163-169
Songbirds exhibit seasonal changes in the volumes of song control nuclei. Birds on long, spring-like days have larger nuclei than do birds on short, winter-like days. The mechanisms mediating volumetric changes have not been determined unequivocally, but testosterone (T) is probably involved. This study examined whether testicular factors are uniquely responsible for seasonal changes in the song system, or whether photoperiod has testis-independent effects. Male American tree sparrows were exposed to one of three photoperiodic conditions: (1) Photosensitive birds were retained on short days (8L:16D). Plasma T is rarely detected in such birds. (2) Photosensitive birds were moved from short days to long days (20L:4D) and photostimulated for three weeks. Photostimulation elevates circulating T in photosensitive birds. (3) Photorefractory birds were held at least four months on 20L:4D. Such birds seldom have detectable levels of T, even though they are on long days. In each condition, there were both intact and castrated birds. Castration typically removes circulating T in tree sparrows. The volumes of the high vocal center (HVC), nucleus robustus archistriatalis (RA), and area X were measured. Song nuclei were largest in intact photostimulated birds. Other long-day birds (i.e. castrated photostimulated, and intact and castrated photorefractory groups) had larger song nuclei than did short-day intact or castrated photosensitive birds and did not differ from each other. These data indicate that photoperiod has both testis-dependent and -independent effects on the volumes of song control nuclei. 相似文献
947.
RL Basser LB To CG Begley CA Juttner DW Maher J Szer J Cebon JP Collins I Russell I Olver 《Canadian Metallurgical Quarterly》1995,1(7):715-721
Women with primary breast cancer associated with extensive axillary node involvement or large primary tumors have a very poor prognosis despite treatment with standard-dose adjuvant chemotherapy. In an attempt to improve the outlook of these patients, we investigated the safety and feasibility of delivering three cycles of high-dose epirubicin and cyclophosphamide supported with filgrastim-mobilized peripheral blood progenitor cells (PBPC). Fifteen previously untreated women, median age 50 (range, 30-58) years, with poor prognosis early stage breast cancer received filgrastim (12 microgram/kg daily for 6 days) prior to chemotherapy to mobilize progenitor cells. Patients were then given three cycles of epirubicin (200 mg/m2) and cyclophosphamide (4 g/m2) at planned 28-day intervals, each followed by infusion of one third of the PBPC collected and daily administration of filgrastim (5 microgram/kg s.c.). Three leukaphereses collected a median of 114.9 (range, 22.7-273.5) x 10(4) granulocyte-macrophage-colony-forming cells/kg body weight. Hemopoietic recovery was rapid after each cycle, and there was no correlation between the rate of recovery and the number of granulocyte-macrophage-colony-forming cells infused. There was a small but significant progressive delay in recovery from hematological and nonhematological toxicities across the three cycles. Left ventricular ejection fraction fell to below 50% in eight (53%) patients, but none developed congestive cardiac failure. Two patients did not complete three cycles because of insufficient PBPC for a third cycle (n = 1) and 2-mercaptoethane sodium sulfonate- related drug reaction during the second cycle (n = 1). There were no deaths during the study or during the follow-up period (median, 70 weeks; range, 50-85 weeks), and no late toxicities occurred. Therefore, we concluded that the delivery of multiple cycles of nonmyeloablative, dose-intensive chemotherapy supported by PBPC and filgrastim is safe, and may be widely applicable to a variety of common chemosensitive cancers with a poor prognosis. The efficacy of three cycles of high-dose epirubicin and cyclophosphamide is to be compared with standard-dose chemotherapy in a randomized trial in patients with high-risk, operable stage II and III breast cancer. 相似文献
948.
Mohammad Nabil Bhuiyan Lesley D. Frame Leslie T. Mushongera 《Advanced Engineering Materials》2023,25(19):2300178
The presence of secondary particles to polycrystalline alloys results in kinetic stabilization of the grain boundaries, which maintains desirable fine microstructures. In some instances, secondary particles trigger abnormal grain growth. The mechanisms influencing abnormal grain growth are still a subject of conjecture. As dispersed fine particles can contribute to abnormal grain growth, it is necessary to clarify the governing mechanism by which this occurs. The current work employs a multiphase field modeling approach to shed light onto abnormal grain growth. Particular attention is placed on understanding the role of grain boundary–particle interactions on abnormal grain growth. The results show that, in the presence of particles, normal grain growth occurs until a pinned state is achieved. In the pinned state, some grains overcome the pinning pressure exerted by some particles by piercing through the particles, which results in abnormal grain growth. The piercing events appear to be entirely random and not related to the size of the interacting particles. None-the-less, a bimodal particle size distribution is observed to lead to abnormal grain growth. A pinning parameter is introduced as a metric to identify the transition from normal to abnormal grain growth. 相似文献
949.
Silicon - In this work, we carried out simulations to demonstrate the effects of using asymmetric channel thickness in conventional double gate junctionless field- effect transistors (DG JLFETs) by... 相似文献
950.