全文获取类型
收费全文 | 2685篇 |
免费 | 8篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 190篇 |
金属工艺 | 58篇 |
机械仪表 | 2篇 |
建筑科学 | 3篇 |
矿业工程 | 8篇 |
能源动力 | 2篇 |
轻工业 | 29篇 |
水利工程 | 1篇 |
石油天然气 | 5篇 |
无线电 | 21篇 |
一般工业技术 | 57篇 |
冶金工业 | 2280篇 |
原子能技术 | 4篇 |
自动化技术 | 29篇 |
出版年
2013年 | 16篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 13篇 |
2002年 | 16篇 |
2001年 | 5篇 |
2000年 | 11篇 |
1999年 | 72篇 |
1998年 | 764篇 |
1997年 | 446篇 |
1996年 | 286篇 |
1995年 | 162篇 |
1994年 | 118篇 |
1993年 | 128篇 |
1992年 | 18篇 |
1991年 | 25篇 |
1990年 | 22篇 |
1989年 | 35篇 |
1988年 | 20篇 |
1987年 | 24篇 |
1986年 | 30篇 |
1985年 | 28篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 15篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1979年 | 7篇 |
1978年 | 12篇 |
1977年 | 48篇 |
1976年 | 90篇 |
1975年 | 18篇 |
1974年 | 17篇 |
1973年 | 21篇 |
1972年 | 15篇 |
1971年 | 15篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1968年 | 6篇 |
1967年 | 6篇 |
1966年 | 5篇 |
1965年 | 4篇 |
1959年 | 4篇 |
1921年 | 5篇 |
排序方式: 共有2693条查询结果,搜索用时 10 毫秒
91.
Conclusions Commonness and differences in yarn structure formation by high-temperature and low-temperature stretching have been shown.Model concepts on the development of structure in high-temperature deformation during the process of high-speed yarn spinning have been examined.It has been found that, on changing the linear density of elementary filaments, the spinning speed, or the position of the lubricating device, the proportion of effective high-temperature and low-temperature deformations changes.Translated from Khimicheskie Volokna, No. 3, pp. 16–19, May–June, 1988. 相似文献
92.
93.
R. F. Geller 《Journal of the American Ceramic Society》1923,6(10):1098-1111
Following a conference with producers and consumers of refractories, a series of proposed laboratory tests were conducted on forty-one commercial brands of brick. The work included reheating at 1450° and 1400°C, quenching, load test, fusion point determination, chemical analyses and petrographic examination. Results of tests are presented, They will be more fully discussed when correlated with service tests now under way. 相似文献
94.
95.
SC Finn 《Canadian Metallurgical Quarterly》1998,7(10):1211-1215
Manganese (Mn) complexes are unstable and dissociate in vivo. Because of the release of this metal, there exists some concern about the potential long-term neurotoxicity associated with the use of Mn-based contrast agents. This latter problem arises because manganese is known to accumulate in specific regions of the brain of people intoxicated by this metal. It was previously demonstrated that Mn can accumulate in the mice brain after administration of 5 micromol/kg of MnCl2, Mn-diethylenetriaminepentaacetate (Mn-DTPA), or Mn-dipyridoxal diphosphate (Mn-DPDP). In order to better characterize the behavior of Mn complexes after administration, this study assesses the regional distribution of Mn in the brain after i.v. injection of a single dose of MnCl2 or Mn-DTPA. Male Wistar rats received an i.v. injection of 5 micromol/kg of 54Mn as MnCl2 or Mn-DTPA. The rats were killed at one and two weeks post exposure. The distribution of the radioactivity in the slices was monitored by autoradiography. For both MnCl2 or Mn-DTPA, we observed that the radioactivity was dispersed in the entire brain, but the radioactivity was higher in several regions. No difference was observed between MnCl2 or Mn-DTPA in the regional distribution of Mn, and no difference was observed between the two times of exposure (1 week or 2 weeks). The uptake of Mn was minimal in corpus callosum. Maximal Mn concentration was observed in the hippocampal region, thalamus, colliculi, amygdala, olfactory nuclei, and cerebellum. 相似文献
96.
Clinical experience of arthroscopy in 12 temporomandibular joints with a clinical diagnosis of closed lock was described. There were 10 patients and all were females with a mean age of 31.2 years (range 20 to 59 years). The antero-lateral approach was used for entry into 11 joints. The clinical findings were adhesions (64%), fibrillation (64%), anterior displacement of disc (36%) and scuffing of the articular surface of the glenoid fossa (9%). Two of the joints that had arthrocentesis prior to arthroscopy did not show any different findings from the rest. Of the 8 patients who had pre-arthroscopy pain, 7 patients (88%) had reduction of the symptom. Three patients (38%) had complete resolution of pain. The range of mouth opening (measured as maximal incisor opening) increased in all patients two weeks following arthroscopy. The average change in maximal incisor opening was 40.3% with a range of 22% to 85%. The mean follow-up was 34 months (range 4 to 68 months). 相似文献
97.
98.
JR Montague M Bovarnick SC Effren CC Southerland 《Canadian Metallurgical Quarterly》1998,88(9):429-436
To test the null hypothesis that limb dominance (laterality) and side of complaint are not associated in a diverse population, nearly 400 patients (40% male, 60% female) of varying age and body size from three South Florida podiatric medical teaching facilities were surveyed in 1995-1996. Radiographs of feet were available for 15% of the patients, and the metatarsus adductus angle was measured on each x-ray. The typical patient was a women (median age, 49 years) of average body weight and average body-mass index. No statistical association was found between laterality and side of complaint in the broader sample, although a significant association did appear in the subsample of patients with bilateral x-rays. The prevalence of metatarsus adductus deformity (metatarsus adductus angle > 15 degrees) among patients with x-rays was 62%. No sex-specific, age-specific, or body size-specific associations were found between handedness and metatarsus adductus deformity. 相似文献
99.
Pregnancy is thought to have an ameliorating effect on endometriosis, inducing a state of quiescence. We report a case of ruptured endometriotic cyst in pregnancy successfully treated by laparoscopic ovarian cystectomy. Our patient subsequently progressed uneventfully to deliver a healthy baby girl at term. Laparoscopic ovarian cystectomy in pregnancy, even with ruptured cysts, appeared to be safe in trained hands with similar benefits of reduced post-operative morbidity. 相似文献
100.
KH Yeh MT Lin DT Lin JL Tang LT Lui JF Lin YS Chang AL Cheng SC Yu KJ Chang YC Chen 《Canadian Metallurgical Quarterly》1998,49(3):237-244
BACKGROUND: Epidemiologic studies are necessary to determine the prevalence of allergic diseases. This varies widely depending on allergen preparations and patients studied. OBJECTIVE: To investigate the prevalence of atopic disease, skin test reactivity, total and specific IgE to common allergens, and other variables in a sample of students from Málaga, southern Spain. METHODS: Three hundred sixty-five students (age 17.9 +/- 1.18) were interviewed by an allergist. Skin prick tests were performed with Dermatophagoides pteronyssinus, Artemisia vulgaris, Plantago lanceolata, Chenopodium album, Olea europaea, Phleum pratense, Parietaria judaica, Cynodon dactylon, Alternaria tenuis, and cat dander. Total and specific IgE to D. pteronyssinus, Olea, and Parietaria were determined. RESULTS: Of all subjects studied, 19.9% suffered from rhinoconjunctivitis, 4.1% rhinoconjunctivitis plus asthma, 3.1% asthma alone, and 0.8% atopic dermatitis; 46.4% had a positive skin test to at least one allergen (28.2% to D. pteronyssinus, 20.4% to Olea, 13.8% to Phleum); and 43% had total IgE > 100 kU/L and 44.7% a family history of atopy. Allergic symptoms were strongly associated with skin test positivities and family allergic history. Patients with asthma or skin prick test positive had higher total IgE values than others (P < .01). There was a significant correlation between specific IgE values and wheal size in skin test. CONCLUSIONS: Our findings confirm the high prevalence of atopic diseases, and the close relationship of skin tests reactivity (or presence of specific IgE) to allergens with symptoms of asthma and rhinitis. The presence of a family history of allergic diseases influences the development of positive skin tests and atopic illness. Dermatophagoides pteronyssinus and pollen of Olea europaea were found to be the most common allergens. 相似文献