全文获取类型
收费全文 | 2270篇 |
免费 | 2篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 35篇 |
金属工艺 | 1篇 |
轻工业 | 10篇 |
水利工程 | 1篇 |
无线电 | 3篇 |
一般工业技术 | 8篇 |
冶金工业 | 2207篇 |
原子能技术 | 1篇 |
自动化技术 | 4篇 |
出版年
2019年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2011年 | 1篇 |
2010年 | 4篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 74篇 |
1998年 | 711篇 |
1997年 | 432篇 |
1996年 | 249篇 |
1995年 | 131篇 |
1994年 | 99篇 |
1993年 | 127篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 17篇 |
1989年 | 24篇 |
1988年 | 33篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1978年 | 3篇 |
1977年 | 61篇 |
1976年 | 144篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1968年 | 1篇 |
1964年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有2272条查询结果,搜索用时 31 毫秒
21.
EM Aliouat E Dei-Cas A Ouaissi F Palluault B Soulez D Camus 《Canadian Metallurgical Quarterly》1993,77(2):209-217
Cigarette smoking has been shown to increase consequent to the acute administration of methadone. This suggests the possibility that differences in maintenance dose levels might be associated with differential smoking rates. It is of special concern that higher maintenance levels of methadone may lead to more cigarette smoking because of the putative beneficial effects of higher doses on illicit drug use, treatment retention, and the like. Two experiments were conducted to test the hypothesis that higher maintenance doses of methadone are related to more cigarette smoking. Smoking was measured by self-report and expired carbon monoxide, and the amounts were correlated with subjects' methadone dose levels. The results showed smoking rates of 85% and that self-reported smoking significantly correlated (r = -.52) with CO. Maintenance doses, however, were not correlated with smoking levels. This suggests that the acute effects of methadone on smoking are nullified as clients habituate to dose level, and that decisions regarding appropriate methadone dosage can be made on other grounds. 相似文献
22.
D Young KK Midha MJ Fossler EM Hawes JW Hubbard G McKay ED Korchinski 《Canadian Metallurgical Quarterly》1993,44(5):433-438
Unequal metabolic responses to trauma by women and men have been suggested, but an explicit investigation demonstrating this conjecture has not been made. The responses of resting energy expenditure (REE) and nitrogen balance for 3 days before and 7 days after skeletal trauma were determined for female and male rats. Food intake and body weight were recorded daily, and 24-h urine samples were collected. Baseline REE and nitrogen balance were obtained for 3 consecutive days before induction of trauma. Then rats were divided into female trauma (n = 8), male trauma (n = 7), female control (n = 8), and male control (n = 7) groups. Trauma was produced by bilateral femoral fracture to anesthetized rats. Control rats were anesthetized without skeletal trauma. Traumatized rats were fed ad libitum for 7 days, and control rats were pair fed with the traumatized rats. The results showed that REE increased and nitrogen balance decreased in traumatized male rats relative to their controls. Traumatized female rats had increased REE and unchanged nitrogen balance compared with their controls. Traumatized female rats had a larger percentage increase in REE on days 5 through 7 than did traumatized male rats. These findings demonstrate a difference between female and male rats in response to trauma. Female rats use more energy and lose less nitrogen after trauma than do male rats. The results suggest that recommendations for increased energy and protein needs after trauma should consider the sex of the subject intended to be fed. 相似文献
23.
Dark, shrunken neurons frequently occur as artefacts in immersion fixed tissue. Perfusion fixation will prevent artefacts of this type. However, morphologically identical neurons have been described as truly degenerated cells in perfusion fixed brains in various pathological conditions. Since adequate perfusion is difficult to obtain in some pathological conditions, the question still remains whether the dark neurons found in some of these situations are true in vivo phenomena or artefacts caused by inadequate fixation. In the present study rat brains with cryogenic lesions were fixed in situ by microwave irradiation. With this method no artefactually changed dark neurons were observed in the normal parts of the brains. In the cryogenic lesions, however, a narrow rim of dark, shrunken neurons occurred adjacent to the normal cortex. This zone was identical to that observed in perfusion fixed tissue. Since inadequate fixation due to uneven perfusion of the damaged tissue is prevented with this method, we suggest that the neuronal changes represent true in vivo phenomena. Fixation with microwave irradiation can thus be used to differentiate between artefactually changed and truly degenerated dark neurons in various pathological conditions. 相似文献
24.
We reviewed 187 depth recorded seizures in 33 patients with non-lesional temporal lobe complex partial seizures. All patients had a minimum of 1 year follow-up following temporal lobectomy. We classified seizure onset pattern as rhythmic activity, attenuation, or repetitive spikes or spike wave complexes. The most common pattern of seizure onset was rhythmic activity and the next most common pattern was repetitive spikes. Seventy-five seizures (49%) had only one seizure onset pattern, and 79 seizures (51%) had a combination of seizure onset patterns. The degree of hippocampal gliosis strongly predicted the type of seizure onset pattern (Chi square = 24.07, 2 d.f., P < 0.01). The rhythmic activity pattern was associated with mild gliosis, and the repetitive spike pattern was associated with severe gliosis. We classified seizure onset as focal or regional based on the number of electrode contacts that were involved by the ictal EEG. A focal seizure onset was associated with an excellent outcome following temporal lobectomy. 相似文献
25.
26.
27.
EM de Kleijn WJ Oyen RA Claessens FH Corstens JW van der Meer 《Canadian Metallurgical Quarterly》1995,155(18):1989-1994
BACKGROUND: We assessed the utility of scintigraphy with indium 111-labeled polyclonal human IgG scintigraphy in patients with fever of unknown origin that fulfilled the criteria of temperature of 38.3 degrees C or more for at least 3 weeks and no diagnosis during 1 week of hospital admission. We compared the utility of this technique with results of scintigraphic techniques reported in the literature. METHODS: Data for all patients seen at our university hospital in whom 111In-IgG scanning was performed were analyzed and checked for the criteria for fever of unknown origin. The literature on the utility of scintigraphic techniques in patients with fever of unknown origin was reviewed. RESULTS: We studied 24 patients with fever of unknown origin. In 13 patients, focal 111In-IgG accumulation was observed. In nine (38%) of those, the positive 111In-IgG scintigram led to the final diagnosis; in the other four patients (17%), the scintigraphic findings were not helpful. In the 11 patients with negative 111In-IgG scans, extensive diagnostic workup produced no infection as the final diagnosis in nine patients (38%), one had an abscess in a renal cyst that was detected several months later, and in the other the cause of fever was an infected intravenous line. The overall sensitivity and specificity of 111In-IgG scintigraphy were 81% and 69%, respectively. The positive predictive value was 69% and the negative predictive value was 82%. CONCLUSIONS: Our results show that 111In-IgG scintigraphy significantly contributed to the diagnostic process in patients with fever of unknown origin. A positive scan increased the likelihood of finding the cause of the fever, and a negative scan ruled out an inflammatory component with a high degree of certainty. These data compare favorably with data in the literature concerning other radiopharmaceuticals; a larger prospective evaluation of this technique is indicated. 相似文献
28.
J Barrette R Bellwied P Braun-Munzinger WE Cleland T Cormier G Dadusc G David J Dee O Dietzsch M Fatyga SV Greene JV Germani JR Hall TK Hemmick N Herrmann RW Hogue B Hong K Jayananda D Kraus BS Kumar R Lacasse D Lissauer WJ Llope TW Ludlam R Majka SK Mark JT Mitchell M Muthuswamy E O'Brien C Pruneau FS Rotondo da Silva NC J Simon-Gillo U Sonnadara J Stachel H Takai EM Takagui TG Throwe L Waters C Winter D Wolfe CL Woody N Xu Y Zhang Z Zhang C Zou 《Canadian Metallurgical Quarterly》1995,52(5):2679-2683
29.
IuA Magakian EM Karalova LO Abroian SA Karapetian 《Canadian Metallurgical Quarterly》1997,39(8):705-710
Cytophotometry of rat blood erythroid cells during anaemia, induced by phenylhydrazin (4-8 days from the beginning of injections), revealed that all forms of bone marrow containing haemoglobin were thrown into the blood. On its peak (4th day), the greatest contribution in blood haemoglobinization (50%) is made by microcytes. From the 5th day and up to the end of the restoration period the important role in this process is played by macrocytes. From the 6th day the role of normocytes increases, whose contribution by 8th day reaches 70% of the whole haemoglobin amount in blood. In contrary to anaemizated birds, whose erythroid cells ripen in blood, in rats all the transformations of erythron during anaemia are accomplished in bone marrow. 相似文献
30.