全文获取类型
收费全文 | 2232篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 5篇 |
金属工艺 | 2篇 |
机械仪表 | 3篇 |
轻工业 | 1篇 |
石油天然气 | 2篇 |
无线电 | 1篇 |
一般工业技术 | 8篇 |
冶金工业 | 2202篇 |
原子能技术 | 1篇 |
自动化技术 | 9篇 |
出版年
2021年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2000年 | 1篇 |
1999年 | 56篇 |
1998年 | 629篇 |
1997年 | 374篇 |
1996年 | 227篇 |
1995年 | 114篇 |
1994年 | 112篇 |
1993年 | 134篇 |
1992年 | 18篇 |
1991年 | 22篇 |
1990年 | 19篇 |
1989年 | 32篇 |
1988年 | 31篇 |
1987年 | 36篇 |
1986年 | 27篇 |
1985年 | 22篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 26篇 |
1978年 | 4篇 |
1977年 | 88篇 |
1976年 | 190篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1960年 | 1篇 |
1955年 | 5篇 |
排序方式: 共有2234条查询结果,搜索用时 15 毫秒
71.
A case of a mature posterior cervical teratoma resembling two fingers and a case of a lumbosacral limb are presented. These are at least the seventh and eighth reported paraspinous or occipital teratomas with recognizable extremity development. Both anomalies had intradural extension and required exploration to decrease the likelihood of future spinal cord tethering. Preoperative evaluation, surgical technique, postoperative follow-up, and review of the literature are presented. 相似文献
72.
RH Messer 《Canadian Metallurgical Quarterly》1995,21(5):221-226
Current cancer screening recommendations for women have been reviewed. Controversies have been identified. Many additional references are available upon request. 相似文献
73.
mRNA and cytoskeletal filaments 总被引:1,自引:0,他引:1
There is evidence that low birth weight and poor growth in early life cause a long-term predisposition to non-insulin-dependent diabetes. Morphological changes were assessed in fetal rat pancreas subjected to both pre- and post-natal maternal protein deprivation (LP). Further groups were subjected to purely prenatal maternal protein deprivation (preLP) and purely postnatal maternal protein deprivation (postLP), as well as a control group. The results show that the LP and postLP groups had fewer but larger islets than the control group, while the preLP group had more numerous, smaller islets. All three low protein groups had more irregularly shaped islets than the control group. There was a reduction in the amount of beta cells within each islet in all three protein-deprived groups. The LP and postLP groups showed a reduction in the percentage of islet tissue and beta cells per pancreas, but the percentage of islet tissue expressed per unit body weight was similar in all four groups. These results show that in maternal protein deprivation, homeostatic mechanisms ensure a constant amount of pancreatic endocrine tissue per unit of body weight. However, there remain major structural changes in the size, shape, and composition of the islets. These results support the theory that early development profoundly affects the structure of the pancreas and may play a role in the later development of adult diseases, such as non-insulin-dependent diabetes mellitus. 相似文献
74.
A procedure was developed for the detection and determination of bixin and norbixin in human plasma by reversed-phase HPLC with a sensitivity limit of 5 micrograms l-1. A group of seven volunteers ingested a single dose of 1 ml of a commercial Annatto Food Color (16 mg of cis-bixin in soybean oil). The presence of bixin (cis and trans) and norbixin (cis and trans) was demonstrated in the plasma at average levels of 11.6, 10.1, 2.8 and 0 micrograms l-1 of bixin and 48, 58, 53 and 29 micrograms l-1 of norbixin after 2, 4, 6 and 8 h, respectively. Considerable individual variations were observed. Complete plasma clearance generally occurred for bixin by 8 h and for norbixin by 24 h after ingestion of cis-bixin. 相似文献
75.
76.
77.
78.
Helicobacter pylori infection is an important cause of peptic ulcer disease and chronic gastritis. Infection with this bacterium stimulates the production of immunoglobulin (Ig) G antibody. Salivary IgG antibody tests to detect H pylori infection offer a convenient and noninvasive method of diagnosis. To evaluate an IgG salivary antibody kit, saliva was collected from 157 out-patients with dyspepsia referred for endoscopy to a tertiary centre. A salivary IgG ELISA antibody assay was performed using the Helisal Helicobacter pylori (IgG) assay kit, and at least four gastric biopsies were obtained. H pylori infection was confirmed by demonstration of the organism on Warthin-Starry silver stain (sensitivity 85%, specificity 55%). The prevalence of infection with H pylori was 30%. When the analysis was redone, excluding those treated with eradication therapy, the results were similar (sensitivity 86%, specificity 58%). The positive predictive value of the assay was 45% and the negative predictive value was 90%. Despite the ease of sampling, the assay used has limited diagnostic utility, lacking the predictive value to indicate which patients referred with dyspeptic symptoms to a tertiary care setting are infected with H pylori. 相似文献
79.
FS Baker RA Daley RH Bradley 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(8):878-883
The surface oxygen content of selected wood‐based phosphoric acid‐activated carbons was quantified using X‐ray photoelectron spectroscopy (XPS) and correlated with the residual bulk phosphate levels of the carbons and their adsorptivity in solution. The adsorption of Al3+, Cu2+, and para‐chlorophenol, respectively, from water decreased as a function of increasing surface oxygen content of the carbons. When the carbon of lowest surface oxygen content was oxidized with ozone to impart a surface oxygen content comparable to that of a carbon with a much higher phosphate level, adsorption of Al3+, Cu2+, and para‐chlorophenol from water decreased proportionally. The increase in polarity of the carbon surface was accompanied by a decrease in pH and appeared to be the dominant factor with respect to the adsorption of the target species from water. Copyright © 2005 Society of Chemical Industry 相似文献
80.
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