全文获取类型
收费全文 | 1243篇 |
免费 | 4篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 1篇 |
综合类 | 4篇 |
化学工业 | 7篇 |
金属工艺 | 1篇 |
机械仪表 | 8篇 |
建筑科学 | 3篇 |
能源动力 | 2篇 |
轻工业 | 15篇 |
石油天然气 | 1篇 |
无线电 | 1篇 |
一般工业技术 | 2篇 |
冶金工业 | 1188篇 |
原子能技术 | 1篇 |
自动化技术 | 19篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 11篇 |
2012年 | 3篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 9篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 30篇 |
1998年 | 348篇 |
1997年 | 195篇 |
1996年 | 158篇 |
1995年 | 54篇 |
1994年 | 70篇 |
1993年 | 71篇 |
1992年 | 7篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1978年 | 5篇 |
1977年 | 38篇 |
1976年 | 97篇 |
1975年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有1253条查询结果,搜索用时 15 毫秒
41.
ER Righini R Alvisi S Bortolazzi E Marangoni G Gritti 《Canadian Metallurgical Quarterly》1998,64(9):399-407
In the cranio-facial region the giant-cell reparative granuloma (GCRG) is a typical lesion of the maxillary bones. Because giant-cell reparative granuloma is not strictly a granuloma, clinically and histologically, many authors prefer call it giant-cell lesion (GCL). A review of the literature have along with our experiences is reported. Authors present 17 patients with giant-cell lesion and their results, treated at the Maxillo-Facial Department of Parma. Clinical, radiographic and pathologic features were evaluated and differential diagnosis was considered, showing the real great difficulty in differential diagnosis also and especially for surgical treatment. 相似文献
42.
ER Floyd 《Canadian Metallurgical Quarterly》1986,34(10):3246-3249
43.
44.
The type and distribution of keratins (K) in malignant tumors of eyelids were examined immunohistochemically to understand the pathomechanism of intercellular interactions. All of the tumor cells in the basal cell carcinoma were positive for K14, which is specific for basal cells, whereas all of them were negative for K10, which is specific for suprabasal layers in stratified squamous epithelia. These findings suggest that basal cell carcinoma may consist of uniform, basal cell-like tumor cells. On the other hand, the squamous cell carcinoma and sebaceous carcinoma, which were positive for either K14 or K10 to varying extent, may consist of various tumor cells with different types and degrees of differentiation. In these tumors, K14 was frequently detected throughout the border cells of the tumor mass. Apoptotic bodies were detected at the region where this continuous distribution of K14 was interrupted. These findings may help to clarify the pathomechanism of the interactions between the tumor cells and stromal cells. 相似文献
45.
46.
ER Moxon 《Canadian Metallurgical Quarterly》1997,350(9086):1240-1244
Genetics, cell biology, and whole-genome sequencing of pathogens have changed dramatically the opportunities to investigate the epidemiology, pathogenesis, diagnosis, and control of microbial diseases. For example, recombinant DNA and PCR are powerful tools used to isolate genes whose role in pathogenicity can be investigated in biologically relevant virulence assays. Vaccines that target one or more of these genes can then be developed. Complete genome sequences of microbes provide an inventory of the genes encoding every virulence factor and potential immunogen. Candidate vaccines can be selected and developed using various approaches, including the recent innovation of immunisation with nucleic acids. Although many successful vaccines have been and will continue to be developed through empirical approaches, molecular microbiology provides a rational basis for discovery, development, and implementation of safer, more effective and, potentially cheaper vaccines. 相似文献
47.
KM Egan MJ Stampfer BA Rosner D Trichopoulos PA Newcomb A Trentham-Dietz MP Longnecker R Mittendorf ER Greenberg WC Willett 《Canadian Metallurgical Quarterly》1998,7(5):359-364
For the study of the relationship of the pelviureteric system of one kidney to that of the contralateral one, bilateral cutaneous ureterostomy was performed in 14 dogs. The renal pelvis (RP) and ureter (U) of one side were distended separately with a balloon filled with saline in increments of 1 and 0.25 ml, respectively, and the pressure response of the contralateral RP and U was recorded. The test was repeated after anesthetization of the RP and U. RP distension with 1 ml of saline effected a pressure rise (P < 0.05) in the ipsilateral RP but no pressure response in the ipsilateral U or the contralateral RP or U (P > 0.05). RP distension with 2, 3, and 4 ml of saline induced a significant pressure rise in the ipsi- and contralateral RP but not in the ureters. Ureteric distension produced a pressure elevation (P < 0.05) on the ipsilateral U but had no effect on the contralateral U (P > 0.05) or on either of the renal pelves (P > 0.05). Distension of the anesthetized RP or U effected no pressure response in any of the ipsi- or contralateral RPs or Us. In conclusion, distension of the RP with large volumes led to an increase in pressure in the contralateral RP but not in the U. A reflex relationship is postulated to exist between the two renal pelves and to be mediated through a reflex we call the reno-renal pelvic reflex. It seems that this reflex acts to allow either of the kidneys to share an extra load of the other one by increasing the contractile activity of the RP, thus assumedly assisting the regulation of urine flow. 相似文献
48.
LJ Shaw ED Peterson LK Shaw KL Kesler ER DeLong FE Harrell LH Muhlbaier DB Mark 《Canadian Metallurgical Quarterly》1998,98(16):1622-1630
BACKGROUND: Exercise testing is useful in the assessment of symptomatic patients for diagnosis of significant or extensive coronary disease and to predict their future risk of cardiac events. The Duke treadmill score (DTS) is a composite index that was designed to provide survival estimates based on results from the exercise test, including ST-segment depression, chest pain, and exercise duration. However, its usefulness for providing diagnostic estimates has yet to be determined. METHODS AND RESULTS: A logistic regression model was used to predict significant (>/=75% stenosis) and severe (3-vessel or left main) coronary artery disease, and a Cox regression analysis was used to predict cardiac survival. After adjustment for baseline clinical risk, the DTS was effectively diagnostic for significant (P<0.0001) and severe (P<0.0001) coronary artery disease. For low-risk patients (score >/=+5), 60% had no coronary stenosis >/=75% and 16% had single-vessel >/=75% stenosis. By comparison, 74% of high-risk patients (score <-11) had 3-vessel or left main coronary disease. Five-year mortality was 3%, 10%, and 35% for low-, moderate-, and high-risk DTS groups (P<0.0001). CONCLUSIONS: The composite DTS provides accurate diagnostic and prognostic information for the evaluation of symptomatic patients evaluated for clinically suspected ischemic heart disease. 相似文献
49.
Changes in the kinetic properties of voltage-activated sodium currents (I(Na)) were studied in rat retinal ganglion cells during in vivo differentiation. Whole-cell recordings from cells maintained as retinal slices or whole-mounts were examined using the patch-clamp technique in the perforated patch mode. Voltage-clamp recordings revealed significant ontogenetic modifications in key properties of I(Na) and the present study described for the first time the detailed time course of such alterations. I(Na) was first expressed on embryonic day 17/18 (E17/18). Current density increased during development from an average of -81 pA/pF on E17/18 to a maximum of -747pA/pF on postnatal day 10/12 (P10/12). Simultaneously, the activation of I(Na) shifted towards more negative potentials, reflected by a shift in the potential of half-activation from -14.1 mV on E17/18 to - 37.5 mV on P10/12. No significant changes in these parameters were observed after P10/12. Steady-state inactivation shifted first towards more positive potentials, reflected by a shift in the potential of half-inactivation from -51 mV on E17/18 to -38 mV on P3/5, but shifted back towards more negative values thereafter (-44 mV in the adult). The most striking feature of I(Na) in rat RGCs was a transient slowing of I(Na) kinetics that was never described before. Time to peak and decay time constants increased between E20 and P5, resulting in slow and broad sodium currents within a developmental period that is characterized by intensive synaptogenesis in the target structures of retinal ganglion cells and maximum retinal ganglion cell death. Thereafter, time to peak and decay time constants decreased again to values found before E20, resulting in rapid sodium spikes. In conclusion, sodium currents in rat retinal ganglion cells displayed substantial electrophysiological changes during pre- and postnatal development. These changes in the sodium system had different temporal time patterns, indicating that they may play specific roles during the development of the visual system. 相似文献
50.