全文获取类型
收费全文 | 4196篇 |
免费 | 0篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 16篇 |
建筑科学 | 2篇 |
轻工业 | 4篇 |
无线电 | 3篇 |
一般工业技术 | 11篇 |
冶金工业 | 4143篇 |
原子能技术 | 5篇 |
自动化技术 | 10篇 |
出版年
2024年 | 1篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 2篇 |
2010年 | 1篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2003年 | 7篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 128篇 |
1998年 | 1291篇 |
1997年 | 713篇 |
1996年 | 462篇 |
1995年 | 266篇 |
1994年 | 192篇 |
1993年 | 260篇 |
1992年 | 42篇 |
1991年 | 48篇 |
1990年 | 45篇 |
1989年 | 71篇 |
1988年 | 60篇 |
1987年 | 64篇 |
1986年 | 42篇 |
1985年 | 49篇 |
1984年 | 2篇 |
1983年 | 9篇 |
1982年 | 18篇 |
1981年 | 31篇 |
1980年 | 28篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 111篇 |
1976年 | 212篇 |
1975年 | 6篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有4196条查询结果,搜索用时 31 毫秒
941.
JD Nieland K Loviscek K Kono KS Albain AR McCall RK Potkul SG Fisher MP Velders M Petersson R Kiessling WM Kast 《Canadian Metallurgical Quarterly》1998,21(4):317-322
BACKGROUND AND OBJECTIVE: The use of hematopoietic growth factors in association with chemotherapy in human immunodeficiency virus (HIV)-related non-Hodgkin's lymphoma (NHL) has been recommended, but few studies have evaluated its cost-effectiveness. DESIGN AND METHODS: The effects of recombinant granulocyte colony-stimulating factor (G-CSF) were analyzed in 33 consecutive patients with HIV-related NHL treated at a single institution with the same chemotherapy program, ProMACE-CytaBOM, with G-CSF, in 21 cases diagnosed after December 31, 1991, or without G-CSF, in 12 cases diagnosed earlier. Pearson's chi-square analysis and the two-sided Student's t-test were used for statistical comparisons. The method of Kaplan-Meyer and the log-rank-test were used for survival analyses. RESULTS: G-CSF support significantly reduced the frequency of day-1 drug dose reductions (p < 0.001) and of chemotherapy delays (p < 0.001), and improved the actual delivered doses of adriamycin, cyclophosphamide and etoposide (p < 0.02). In patients with a CD4+ count < 0.01 x 10(9)/L, chemotherapy could be given at full doses in 90% of cycles with G-CSF compared to only 20% without it. G-CSF affected neither the frequency and duration of fever and hospitalization nor the complete remission and survival rates after stratification according to the CD4+ count. INTERPRETATION AND CONCLUSIONS: G-CSF support significantly improved dose-intensity in patients with HIV-related NHL treated with aggressive chemotherapy, particularly in the subgroup with a CD4+ count < 0.1 x 10(9)/L, but it did not improve their clinical outcome. 相似文献
942.
JD Dawson 《Canadian Metallurgical Quarterly》1998,54(1):323-330
Sample size calculations based on two-sample comparisons of slopes have been reported by many. This paper extends such discussions to include summary statistics other than slopes, such as post-baseline means, change scores, and final observations. Specifically, sample size formulas for analyses based on a broad class of summary statistics are presented, with modifications proposed to allow for missing data caused by staggered entry and random dropouts. The formulas developed are used to illustrate how required sample size is affected by summary statistic choice, variance parameters, the type of treatment difference of interest, and the manner in which incomplete observations are used in the analysis. An example based on longitudinal data from the Muscatine Study is presented. 相似文献
943.
944.
The in vitro activity of a naturally occurring complex carbohydrate, CAN-296, was evaluated by testing 132 clinical and ATCC isolates of yeast and Aspergillus fumigatus, many of which were azole-resistant. The in vitro susceptibility tests were performed by standardized broth micro- and macrodilution methods and results were compared with those obtained for amphotericin B, fluconazole, ketoconazole, flucytosine and the pneumocandin L-733,560. All tested Candida species showed highly uniform susceptibility to CAN-296 at concentrations of 0.078 to 0.312 microgram/ml; non-albicans Candida were as susceptible to CAN-296 as the Candida albicans strains. Multi-azole-resistant Candida species were highly sensitive to CAN-296. Minimum inhibitory concentration measurements did not differ from minimum lethal concentrations by more than two-fold for all tested Candida species. Aspergillus fumigatus, on the other hand, showed only moderate susceptibility to CAN-296. The kinetics of the anti-Candida activity of CAN-296 was investigated by kill-curve experiments using C. albicans and C. glabrata and the results were compared with those obtain for amphotericin B. CAN-296 was found to be rapidly fungicidal in concentrations ranging from 4-16 fold the mean MIC value. The broad spectrum of anti-Candida activity together with the rapid fungicidal effect make this complex carbohydrate a promising agent for clinical use. 相似文献
945.
946.
FM Uckun Y Yanishevski N Tumer B Waurzyniak Y Messinger LM Chelstrom EA Lisowski O Ek T Zeren H Wendorf MC Langlie JD Irvin DE Myers GB Fuller W Evans R Gunther 《Canadian Metallurgical Quarterly》1997,3(3):325-337
Withdrawal responses to mechanical and thermal stimuli applied to the plantar surface of the hindpaw were measured before and after bone damage. In separate groups of rats the bone was injured by scraping the periosteum of the tibia, drilling a hole through the tibia, aspirating bone marrow, or drilling a hole through the calcaneus. Scraping the periosteum did not alter withdrawal responses to the mechanical stimuli, or evoke nocifensive behavior. In contrast, secondary mechanical hyperalgesia and allodynia, and cold allodynia were observed after a hole was drilled through the tibia or calcaneus and after aspiration of bone marrow. The secondary hyperalgesia peaked at 2 h after injury. Drilling a hole through the calcaneus permitted primary hyperalgesia to be easily quantified. Primary hyperalgesia lasted up to 24 h after injury. Nocifensive behavior characterized by a lifting and guarding of the damaged limb was also observed after a hole was drilled through the tibia or calcaneus. Drilling a hole through the tibia or calcaneus should be a useful experimental model for investigating the mechanisms underlying bone pain. 相似文献
947.
AM Orville N Elango JD Lipscomb DH Ohlendorf 《Canadian Metallurgical Quarterly》1997,36(33):10039-10051
Protocatechuate 3,4-dioxygenase (3,4-PCD) catalyzes the oxidative ring cleavage of 3,4-dihydroxybenzoate to produce beta-carboxy-cis, cis-muconate. Crystal structures of Pseudomonas putida3,4-PCD [quaternary structure of (alphabetaFe3+)12] complexed with seven competitive inhibitors [3-hydroxyphenylacetate (MHP), 4-hydroxyphenylacetate (PHP), 3-hydroxybenzoate (MHB), 4-hydroxybenzoate (PHB), 3-fluoro-4-hydroxybenzoate (FHB), 3-chloro-4-hydroxybenzoate (CHB), and 3-iodo-4-hydroxybenzoate (IHB)] are reported at 2.0-2.2 A resolution with R-factors of 0. 0.159-0.179. The inhibitors bind in a narrow active site crevasse lined with residues that provide a microenvironment that closely matches the chemical characteristics of the inhibitors. This results in as little as 20% solvent-exposed surface area for the higher-affinity inhibitors (PHB, CHB, and FHB). In uncomplexed 3,4-PCD, the active site Fe3+ is bound at the bottom of the active site crevasse by four endogenous ligands and a solvent molecule (Wat827). The orientations of the endogenous ligands are relatively unperturbed in each inhibitor complex, but the inhibitors themselves bind to or near the iron in a range of positions, all of which perturb the position of Wat827. The three lowest-affinity inhibitors (MHP, PHP, and IHB) yield distorted trigonal bipyramidal iron coordination geometry in which the inhibitor C4-phenolate group displaces the solvent ligand. MHB binds within the active site, but neither its C3-OH group nor the solvent molecule binds to the iron. The C4-phenolate group of the three highest-affinity inhibitors (PHB, CHB, and FHB) coordinates the Fe3+ adjacent to Wat827, resulting in a shift in its position to yield a six-coordinate distorted octahedral geometry. The range of inhibitor orientations may mimic the mechanistically significant stages of substrate binding to 3, 4-PCD. The structure of the final substrate complex is reported in the following paper [Orville, A. M., Lipscomb, J. D., & Ohlendorf, D. H. (1997) Biochemistry 36, 10052-10066]. 相似文献
948.
Technically, renal transplantation has been feasible for over four decades. However, immunological injury to the transplanted kidney continues to be the leading cause of graft loss. While current immunosuppressive protocols yield a 1-year graft survival of > 90%, the trade off is increased risks from nephrotoxicity to manifestations of long-term immunosuppression. We have developed techniques which would allow genetic manipulation of the donor kidney while utilizing current procurement and preservation protocols. 相似文献
949.
The demonstration of tartrate-resistant acid phosphatase (TRAP) activity has long been a cornerstone in the diagnosis of hairy cell leukemia (HCL). Recently a monoclonal antibody to this enzyme has been developed that can be used in an immunoperoxidase method on paraffin-embedded tissues. By using a peroxidase-labeled streptavidin biotin method, paraffin sections of B5 and formalin-fixed tissue from 86 cases of HCL (41 bone marrow, 36 spleen, 9 liver) were stained with the antibody to TRAP and compared against staining for CD20 (L26) and DBA.44 (DAKO, Carpinteria, Calif). In addition, 193 specimens (127 bone marrow, 42 lymph node, 19 spleen, 5 other) from a variety of neoplastic and nonneoplastic hematologic conditions were stained using the monoclonal antibody to TRAP. For comparison, these cases were also stained with DBA.44. In the cases of HCL, 80 of 86 specimens were immunoreactive for TRAP. While the antibody to TRAP generally stained less than 50% of the hairy cells, CD20 and DBA.44 stained 90% and 50% to 60% of hairy cells, respectively. Two of three cases of marginal zone lymphoma showed weak immunoreactivity to the TRAP antibody. Two specimens from a patient with Gaucher's disease and 8 of 13 cases of mastocytosis also showed positivity to the TRAP antibody in the macrophages and mast cells, respectively. In contrast, staining for DBA.44 was positive in 3 of 9 cases of B-cell large cell lymphoma, 1 of 4 cases of mantle cell lymphoma, and in the paraimmunoblasts of 1 of 7 cases of small lymphocytic lymphoma. Only HCL was TRAP and DBA.44 positive. This antibody to TRAP is a useful addition to the diagnosis of HCL but should be used in conjunction with CD20 and DBA.44. The use of this antibody to determine minimal residual disease after chemotherapy was not addressed. 相似文献
950.
Elcatonin, used for treatment of hypercalcaemia, Paget's disease and osteoporosis, causes flushing of the face and hands. To determine whether this was because of increased levels of vasoactive intestinal peptide, which is known to induce vasodilation, the effect of elcatonin on the plasma levels of vasoactive intestinal peptide was studied in five healthy volunteers. After a single intramuscular administration of elcatonin (20 int units), peak plasma elcatonin levels (approx. 30 pg mL-1) were achieved 30 min after injection. Plasma vasoactive intestinal peptide concentrations rose similarly with peak levels of about 17 pg mL-1 after 30 min. Side-effects such as cutaneous flushing (most obvious in the face and hands) occurred to an extent dependent on the amount of elcatonin administered, and declined over 45 min in parallel with the fate of plasma vasoactive intestinal peptide. The side-effects of elcatonin, especially cutaneous flushing, seem to be closely connected with vasoactive intestinal peptide. 相似文献