全文获取类型
收费全文 | 428篇 |
免费 | 0篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 8篇 |
能源动力 | 1篇 |
轻工业 | 5篇 |
无线电 | 1篇 |
一般工业技术 | 1篇 |
冶金工业 | 409篇 |
自动化技术 | 2篇 |
出版年
2018年 | 1篇 |
2013年 | 1篇 |
2010年 | 1篇 |
2005年 | 4篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 10篇 |
1998年 | 131篇 |
1997年 | 63篇 |
1996年 | 51篇 |
1995年 | 20篇 |
1994年 | 22篇 |
1993年 | 21篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1978年 | 1篇 |
1977年 | 11篇 |
1976年 | 27篇 |
1975年 | 3篇 |
排序方式: 共有428条查询结果,搜索用时 13 毫秒
101.
In the first large-scale survey on the use of alcohol and tobacco and the inhalation of paint thinner by Japanese high school students, a higher percentage of respondents reported past or regular use of these substances than in a 1978 survey. The survey was conducted in 44 high schools. The 14,438 respondents (ages 15-18 years) represented 9 of Japan's 47 geographically distinct urban and rural prefectures. Most (76%) reported that they had consumed alcohol at some time, and 50% reported drinking on a regular basis. Alcohol consumption, drinking partners, and motivation for drinking were compared by student gender, geographic region, and years of education. Fewer students reported smoking cigarettes: 32% had smoked at some time, and 14% smoked regularly. Inhalation of paint thinner was rare: 3% had purposely inhaled it, and 1% had abused it. A significant percentage of the alcohol drinkers also used tobacco and/or thinner, a tendency that was the same despite differences in gender, grade in high school, and urban or rural geographic region. A tendency toward polysubstance use was evident among these high school students. 相似文献
102.
KN Kashkin EV Fle?shman PM Chumakov AG Perevoshchikov 《Canadian Metallurgical Quarterly》1998,34(8):1049-1055
Most colorectal tumors are characterized, among other genetic alterations, by allele loss of the genes located on the short arm of chromosome 17 (17p13.1), including the p53 suppressor gene. In ovarian and mammary-gland tumors, deletions of another candidate tumor-suppressor gene, located in the 17p13.3 chromosome region, were observed. We analyzed allele losses in the loci of the short arm of chromosome 17 (YNZ22, MCT35.1, and the p53 gene) in colorectal-cancer patients from the former Soviet Union. Tumors with cytogenetic alterations in 17p and/or with a detected loss of heterozygosity at the YNZ22 (D17S30) locus were examined for allele losses in the p53 gene using two polymorphic sites. Different methods revealed alterations on 17p in 24 (48%) out of 50 patients with colorectal carcinomas. In all tumors with an allele loss of the YNZ22 marker (15 out of 44 informative cases), which was detected by means of PCR, allele loss of the p53 gene was found (12 out of 15 informative cases). In 5 out of 13 tumors with cytogenetic alterations in 17p, allele loss of the p53 gene was found, with the YNZ22 marker being unaffected. In one of these tumors, the i(17q) marker was found, and in the remaining four tumors, 17p translocations were detected. In 4 out of 5 tumors with translocations affecting 17p, the t(17;20)(q21;p12) translocation was detected. The informativeness of the screening for 17p translocations, using PCR for the YNZ22 locus, and the reasons for discrepancy between the data of PCR and cytogenetic analyses are discussed. 相似文献
103.
104.
Insulin on intravenous administration in dogs caused a rise in blood cholesterol level. This may be due to its direct action on liver or other peripheral structures. On the other hand, insulin administered into the lateral cerebral ventricles in normal as well as in spinal and vagotomized dogs resulted in a lowering of blood cholesterol. In cross circulation studies insulin administered into lateral cerebral ventricles of donor dogs produced a hypocholesterolaemia in the recepient dogs without significant changes in blood cholesterol of donor dogs. It is suggested that some substance may be liberated from some parts of central nervous system due to an action of centrally administered insulin. This substance in turn causes hypocholesterolaemia by acting on liver or some other peripheral structures in dogs. 相似文献
105.
We observed endothelin (ET)-induced contractile responses on prostatic and epididymal segments, as well as the facilitation of an electrically stimulated tone on prostatic segments of isolated rat vas deferens. In both segments, the selective ET(B)-receptor agonists, IRL 1620 and sarafotoxin S6c, produced only a small contraction or no contraction at a concentration of 1 microM. The rank order of contraction potencies (pD2 value) was ET-1 = ET-2 > ET-3 > sarafotoxin S6c = IRL 1620. The maximum responses of ET-induced contractions in the prostatic segments were larger than those in the epididymal segments. The contractile response to ET-3 was antagonized by pretreatment for 30 min with BQ-123 (10 nM), a selective ET(A) receptor antagonist, and BQ-788 (1 microM), a selective ET(B) receptor antagonist. The contractile responses to ET-1 were antagonized by pretreatment with BQ-123 (10 microM), but not with BQ-788 (1 microM). The ET-3-induced facilitation on the twitch response to electrical stimulation in the prostatic segment of the vas deferens was antagonized by BQ-123 (0.1 microM) and BQ-788 (1 microM). The ET-1-induced facilitation was antagonized by pretreatment with BQ-123 (3 microM), but not with BQ-788 (10 microM). These results suggest that in rat vas deferens the ET(A) receptors are divided into BQ-123-sensitive ET(A1) and BQ-123-insensitive ET(A2) subtypes, and the production of a contractile response of smooth muscle as well as the facilitation of neurotransmission are accomplished through mediation by ET(A1)- and ET(A2)-subtypes. 相似文献
106.
Y Lu AK Mathur BA Blunt CC Gluer AS Will TP Fuerst MD Jergas KN Andriano SR Cummings HK Genant 《Canadian Metallurgical Quarterly》1996,11(5):626-637
Dual X-ray absorptiometry (DXA) is widely used to monitor treatment efficacy in reducing the rate of bone mineral loss. In order to assure the validity of these measurements, instrument quality control of the DXA scanners becomes very important. This paper compares five quality control procedures (visual inspection, Shewhart chart with sensitizing rules, Shewhart chart with sensitizing rules and a filter for clinically insignificant mean changes, moving average chart and standard deviation, and cumulative sum chart [CUSUM]) in their ability to identify scanner malfunction by means of (1) an analysis of five longitudinal phantom data sets that had been collected during a clinical trial and (2) an analysis of simulated data sets. The visual inspection method is relatively subjective and depends on the operator's experience and attention. The regular Shewhart chart with sensitizing rules has a high false alarm rate. The Shewhart chart with sensitizing rules and an additional filter for clinically insignificant mean changes has the lowest false alarm rate but a relatively low sensitivity. The CUSUM method has good sensitivity and a low false alarm rate. In addition, this method provides an estimate of the date a change in the DXA scanner performance might have occurred. The method combining a moving average chart and a moving standard deviation chart came closest to the performance of the CUSUM method. Comparing the advantages and disadvantages of all methods, we propose the use of the CUSUM method as a quality control procedure for monitoring DXA scanner performance. For clinical trials use of the more intuitive Shewhart charts may be acceptable at the individual sites provided their scanner performance is followed up by CUSUM analysis at a central quality assurance center. 相似文献
107.
Previous studies have shown that the diuretic hormone atrial natriuretic peptide (ANP) also regulates the steroidogenic responsiveness in isolated Leydig cells from mouse and rat testes. In the present study, we examined the distribution of specific receptors for ANP and C-type natriuretic peptide (CNP) in the testicular compartments of 12-week-old Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). We used an in vitro autoradiographic procedure on slide-mounted frozen testicular sections to localize the receptors of the natriuretic peptide hormone family using 125I-ANP and 125I-CNP as radioligands. A high level of specific 125I-ANP binding sites was localized largely in the Leydig cells of the interstitial compartment; other testicular cells were not significantly labeled. On the other hand, no significant difference was observed in 125I-CNP binding sites in the testicular cells of SHR and WKY. Semiquantitative analysis of the binding sites indicated that the density of 125I-ANP receptor binding in Leydig cells of WKY testis was ninefold higher than in those of SHR testis. A moderate level of 125I-ANP binding was also observed in seminiferous tubules, particularly in the spermatids of both SHR and WKY. 125I-ANP binding in WKY spermatids was approximately 2.5-fold higher than in SHR spermatids. Northern blot analysis showed that mRNA specific for guanylyl cyclase type A (Npra) was expressed at approximately twofold higher levels in WKY than in SHR testis. ANP (1 x 10(-8) mol/L) stimulated fourfold to fivefold increased levels of testosterone production in isolated Leydig cells from normotensive WKY compared with those from SHR. These findings support a new physiological role of ANP in Leydig cells, in which a functional relationship seems to exist between testicular ANP receptor expression and testosterone production and the state of hypertension in SHR. 相似文献
108.
MK Mohapatra MM Samal KN Padhiary PC Dash GN Sahoo BC Patnaik 《Canadian Metallurgical Quarterly》1996,44(6):375-377
Sigmoid volvulus is an unusual cause of intestinal obstruction in children. We report two cases of sigmoid volvulus as a complication of segmental dilatation of the colon occurring in two girls (5 years old and 9 years old) previously treated for chronic constipation. In both cases the constipation had been recognised since the neonatal period mimicking a Hirschsprung's disease, a diagnosis which has been excluded after rectal biopsy. The delayed diagnosis of segmental dilatation of the sigmoid colon followed the volvulus. Segmental colonic resection resulted in both cases in the cure of the constipation. 相似文献
109.
CM Grilo KN Levy DF Becker WS Edell TH McGlashan 《Canadian Metallurgical Quarterly》1996,47(4):426-429
Structured diagnostic interviews were used to determine DSM-III-R axis I and II diagnoses among 136 female psychiatric inpatients. To distinguish comorbidity of eating disorders with axis I and II disorders from simple diagnostic overlap, the frequency and distribution of diagnoses among the 31 patients with an eating disorder and the 105 without an eating disorder were compared. Social phobia, substance use disorders, borderline personality disorder, and avoidant personality disorder were diagnosed in a significantly larger proportion of the group with eating disorders. Future studies should focus on interpreting the meaning of the co-occurrence of these disorders in patients with eating disorders. 相似文献
110.
This study evaluated the expression of the corticosteroid-metabolizing enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta HSD) during in vitro decidualization of human endometrial stromal cells. The cultured stromal cells displayed both NADP(+)-dependent (type 1) and NAD(+)-dependent (type 2) 11 beta HSD activities under basal conditions. Although the cells did not respond to estradiol (E2) added alone, catalytic levels of both isoforms were enhanced by medroxyprogesterone acetate (MPA) and further enhanced by E2 plus MPA. Type I messenger RNA (mRNA) was undetected by Northern analysis of total RNA, but was evident as a 1.5-kilobase band in polyadenylated selected RNA from E2- plus MPA-treated cultures. Use of RT-PCR to augment the sensitivity of mRNA detection revealed the presence of type I mRNA as a faint band in the MPA-treated cultures and as an intense band in the E2- plus MPA-treated cultures. Thus, type I mRNA is present as a low abundance message in the cultured stromal cells whose steady state levels parallel progestin-enhanced enzyme activity. As the expression of several progestin-regulated decidualization markers is also augmented by E2, the results of the present study reveal a correlation between enhanced 11 beta HSD expression and the decidualization reaction. Time-course measurements indicated that elevated 11 beta HSD expression is an early event in the decidualization response, which precedes E2- plus MPA-enhanced PRL production by several days. Clear dose-response effects on both type 1 and type 2 11 beta HSD activities were obtained in cells incubated with 10(-8) mol/liter E2 added together with MPA at concentrations that approximated circulating progesterone levels from the luteal phase (10(-9) mol/liter) through pregnancy (10(-7) mol/liter). Corticosteroids are thought to exert toxic and teratogenic effects on the implanting embryo and could influence trophoblast invasion by regulating extracellular matrix turnover. Therefore, the novel finding that decidualization involves marked enhancement of the corticosteroid-metabolizing capacity of stromal cells suggests a mechanism by which decidual cells could affect the health and invasiveness of implanting trophoblastic cells. 相似文献