全文获取类型
收费全文 | 1575篇 |
免费 | 47篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 13篇 |
化学工业 | 206篇 |
金属工艺 | 13篇 |
机械仪表 | 19篇 |
建筑科学 | 39篇 |
能源动力 | 31篇 |
轻工业 | 93篇 |
水利工程 | 10篇 |
石油天然气 | 15篇 |
无线电 | 131篇 |
一般工业技术 | 240篇 |
冶金工业 | 693篇 |
原子能技术 | 46篇 |
自动化技术 | 74篇 |
出版年
2022年 | 13篇 |
2021年 | 26篇 |
2020年 | 15篇 |
2019年 | 25篇 |
2018年 | 27篇 |
2017年 | 26篇 |
2016年 | 31篇 |
2015年 | 26篇 |
2014年 | 27篇 |
2013年 | 64篇 |
2012年 | 39篇 |
2011年 | 41篇 |
2010年 | 44篇 |
2009年 | 32篇 |
2008年 | 43篇 |
2007年 | 32篇 |
2006年 | 36篇 |
2005年 | 25篇 |
2004年 | 19篇 |
2003年 | 25篇 |
2002年 | 27篇 |
2001年 | 17篇 |
2000年 | 25篇 |
1999年 | 28篇 |
1998年 | 152篇 |
1997年 | 107篇 |
1996年 | 71篇 |
1995年 | 48篇 |
1994年 | 52篇 |
1993年 | 45篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 24篇 |
1989年 | 18篇 |
1988年 | 21篇 |
1987年 | 31篇 |
1986年 | 22篇 |
1985年 | 19篇 |
1984年 | 13篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 33篇 |
1976年 | 47篇 |
1974年 | 12篇 |
1972年 | 13篇 |
1970年 | 11篇 |
排序方式: 共有1623条查询结果,搜索用时 15 毫秒
1.
T Seya M Nomura Y Murakami NA Begum M Matsumoto S Nagasawa 《Canadian Metallurgical Quarterly》1998,1(5):809-816
OBJECT: In this retrospective study, the authors analyzed the frequency, anatomical distribution, and appearance of traumatic brain lesions in 42 patients in a posttraumatic persistent vegetative state. METHODS: Cerebral magnetic resonance (MR) imaging was used to detect the number of lesions, which ranged from as few as five to as many as 19, with a mean of 11 lesions. In all 42 cases there was evidence on MR imaging of diffuse axonal injury, and injury to the corpus callosum was detected in all patients. The second most common area of diffuse axonal injury involved the dorsolateral aspect of the rostral brainstem (74% of patients). In addition, 65% of these patients exhibited white matter injury in the corona radiata and the frontal and temporal lobes. Lesions to the basal ganglia or thalamus were seen in 52% and 40% of patients, respectively. Magnetic resonance imaging showed some evidence of cortical contusion in 48% of patients in this study; the frontal and temporal lobes were most frequently involved. Injury to the parahippocampal gyrus was detected in 45% of patients; in this subgroup there was an 80% incidence of contralateral peduncular lesions in the midbrain. The most common pattern of injury (74% in this series) was the combination of focal lesions of the corpus callosum and the dorsolateral brainstem. In patients with no evidence of diffuse axonal injury in the upper brainstem (26% in this series), callosal lesions were most often associated with basal ganglia lesions. Lesions of the corona radiata and lobar white matter were equally distributed in patients with or without dorsolateral brainstem injury. Moreover, cortical contusions and thalamic, parahippocampal, and cerebral peduncular lesions were also similarly distributed in both groups. CONCLUSIONS: The data indicate that diffuse axonal injury may be the major form of primary brain damage in the posttraumatic persistent vegetative state. In addition, the authors demonstrated in this study that MR imaging, in conjunction with a precise clinical correlation, may provide useful supportive information for the accurate diagnosis of a persistent vegetative state after traumatic brain injury. 相似文献
2.
3.
JM Shin M Kajimura JM Argüello JH Kaplan G Sachs 《Canadian Metallurgical Quarterly》1994,269(36):22533-22537
The transmembrane segments of sarcoplasmic reticulum Ca(2+)-ATPase were determined by trypsinization of cytoplasmic side-out intact sarcoplasmic reticulum vesicles. The membrane portion of tryptic digest comprising the transmembrane fragments, joined by the intravesicular segments, was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after labeling with fluorescein 5-maleimide in the presence of sodium dodecyl sulfate. In this way, seven fluorescent bands of tryptic fragments below 11 kDa were observed which were derived from 4 pairs of membrane spanning segments and one hydrophobic sequence at the C-terminal end. Two peptides of 10.8 and 10.6 kDa had the identical N-terminal sequence beginning at Glu826, representing the transmembrane segments M7 and M8 and their connecting loop. A band at 8.1 kDa contained one peptide beginning at Tyr36 (M1/loop/M2). A 7.7-kDa peptide starting at Leu253 (M3/loop/M4) and a 7.3-kDa peptide beginning at Ala752 (M5/loop/M6) were also observed. A band at 6.7 kDa contained two peptides, one beginning at Ser48 (M1/loop/M2) and another beginning at Tyr763 (M5/loop/M6). In addition, a 4-kDa peptide beginning at Met925 was observed. The size of this peptide did not allow for a complete pair of transmembrane segments, but this peptide could have been derived from trypsinolysis between the last pair of membrane spanning segments. These data therefore provide biochemical evidence for at least 8 transmembrane segments and perhaps two more at the C-terminal end of the enzyme. 相似文献
4.
5.
6.
PURPOSE: We attempted to evaluate the efficacy of transrectal bowel stimulation for neurogenic bowel dysfunction in children with myelodysplasia. MATERIALS AND METHODS: Daily sessions of transrectal electrostimulation were performed on an outpatient basis for 2 to 3 weeks on children with myelodysplasia and stool incontinence. If benefits were noted, 5 to 10 additional daily sessions were performed. Complete success was defined as improvement in all parameters of interest, including decrease in the frequency of daily bowel movements, increased sensation, increased ability to hold stool and a significant subjective change in bowel habits. Moderate success implied improvement in 1 to 3 parameters and treatment failure was defined as lack of improvement in any parameter. RESULTS: A total of 55 children 2 to 14 years old (mean age 6.7) completed a mean of 18 daily sessions per patient of bowel electrostimulation. Followup ranged from 1 to 6 years. Diapers are no longer required due to defecation problems in 14 children older than 3 years. Complete success was achieved in 20 cases (36.3%) and moderate success in an additional 30 (54.5%, overall success rate 90.8%). Specifically, 89% of the patients reported elimination of stooling accidents, 82% reported increased sensation and 71% were able to hold the bowel movement. Overall 68% of the patients noticed significantly improved bowel function. Complete/moderate success of transrectal electro-stimulation was statistically significant for all 4 parameters (p < 0.05), and complete success was significant for increased sensation, ability to hold and episodes of accidents. Therapy failed in 5 children (9%). There were no untoward effects. CONCLUSIONS: Transrectal electrostimulation is a well tolerated and minimally invasive modality that provides sustainable improvement in stool continence in children with myelomeningocele and neuropathic bowel dysfunction. 相似文献
7.
NM Kaplan 《Canadian Metallurgical Quarterly》1998,351(9098):288; author reply 289-288; author reply 290
8.
O Merimsky B Kaplan M Deutsch R Tirosh A Weinreb S Chaitchik 《Canadian Metallurgical Quarterly》1997,21(2):167-177
The effectiveness of detecting melanoma by measuring the intracellular fluorescein fluorescent polarization (IFFP) of patients' SCM (structuredness of the cytoplasmic matrix)-responding lymphocytes was examined. SCM-responding lymphocytes from 46 melanoma patients and 32 healthy volunteers were labeled with fluorescein diacetate and challenged with different stimuli, and the resulting polarization was determined. The polarizations (P) obtained upon stimulation with nothing (P-0), encephalitogenic factor (P-EF), phytohaemagglutinin (P-PHA), or melanoma antigen (P-MEL), and the ratios RR(ef) (P-EF/P-PHA) and RR(mel) (P-MEL/P-PHA) were lower for SCM-responding lymphocytes from the patients as a group than for those of the controls. The specificity and sensitivity of the IFFP tests (using cutoff values) to detect melanoma were 90.6 and 73.9%, respectively. The IFFP tests may facilitate the discrimination between melanoma patients and healthy subjects, and may be used in follow-up of patients with melanoma. 相似文献
9.
10.
In multidigital amputations, it is sometimes better to replant an amputated finger to a different proximal part if a better function can be expected in this position. In our clinical material between October 1991 and March 1994, heterotopic replantation was performed in twelve digits in eleven patients. Three fingers were replanted to the thumb, three to the index, four to the middle, and two to the ring fingers. The functional results were satisfying. The total active range of motion was on an average 24% of a normal finger. Static two-point discrimination was 8.5 mm on an average, and the values for the Semmes-Weinstein test ranged between 3.61 and 6.5. A heterotopic replantation is of special value for primary thumb reconstruction. 相似文献