全文获取类型
收费全文 | 1281篇 |
免费 | 0篇 |
专业分类
综合类 | 4篇 |
化学工业 | 5篇 |
金属工艺 | 2篇 |
机械仪表 | 6篇 |
建筑科学 | 2篇 |
能源动力 | 1篇 |
轻工业 | 3篇 |
水利工程 | 1篇 |
无线电 | 5篇 |
一般工业技术 | 14篇 |
冶金工业 | 1224篇 |
自动化技术 | 14篇 |
出版年
2022年 | 1篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 3篇 |
2008年 | 2篇 |
2006年 | 7篇 |
2005年 | 2篇 |
2003年 | 5篇 |
2002年 | 1篇 |
1999年 | 30篇 |
1998年 | 395篇 |
1997年 | 209篇 |
1996年 | 148篇 |
1995年 | 66篇 |
1994年 | 63篇 |
1993年 | 73篇 |
1992年 | 6篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 22篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1978年 | 2篇 |
1977年 | 36篇 |
1976年 | 77篇 |
1975年 | 2篇 |
1928年 | 1篇 |
1909年 | 1篇 |
1885年 | 4篇 |
排序方式: 共有1281条查询结果,搜索用时 15 毫秒
61.
S Wagner F Deymeer LL Kürz S Benz L Schleithoff F Lehmann-Horn P Serdaro?lu C Ozdemir R Rüdel 《Canadian Metallurgical Quarterly》1998,21(9):1122-1128
Clinical, electrophysiological, and molecular findings are reported for a family with dominant myotonia congenita in which all affected members have experienced long-term fluctuations of the symptom of myotonia. In some patients myotonia is combined with myalgia. The myotonia-causing mutation in this family is in the gene encoding the muscular chloride channel, hCIC-1, predicting the amino acid exchange G200R. We have constructed recombinant DNA vectors for expression of the mutant protein in tsA201 cells and investigation of the properties of the mutant channel. The most prominent alteration was a +100-mV shift of the midpoint of the activation curve. Therefore, within the physiological range the open probability of the mutant channel is markedly smaller than in wild-type. This shift is likely to be responsible for the myotonia in the patients. The fluctuating symptoms of this chloride channelopathy are discussed with respect to short-term fluctuations of myotonia in the sodium channelopathy of potassium-aggravated myotonia. 相似文献
62.
RA McKay LJ Miraglia LL Cummins SR Owens H Sasmor NM Dean 《Canadian Metallurgical Quarterly》1999,274(3):1715-1722
The use of antisense oligonucleotides to inhibit the expression of targeted mRNA sequences is becoming increasingly commonplace. Although effective, the most widely used oligonucleotide modification (phosphorothioate) has some limitations. In previous studies we have described a 20-mer phosphorothioate oligodeoxynucleotide inhibitor of human protein kinase C-alpha expression. In an effort to identify improved antisense inhibitors of protein kinase C expression, a series of 2' modifications have been incorporated into the protein kinase C-alpha targeting oligonucleotide, and the effects on oligonucleotide biophysical characteristics and pharmacology evaluated. The incorporation of 2'-O-(2-methoxy)ethyl chemistry resulted in a number of significant improvements in oligonucleotide characteristics. These include an increase in hybridization affinity toward a complementary RNA (1.5 degrees C per modification) and an increase in resistance toward both 3'-exonuclease and intracellular nucleases. These improvements result in a substantial increase in oligonucleotide potency (>20-fold after 72 h). The most active compound identified was used to examine the role played by protein kinase C-alpha in mediating the phorbol ester-induced changes in c-fos, c-jun, and junB expression in A549 lung epithelial cells. Depletion of protein kinase C-alpha protein expression by this oligonucleotide lead to a reduction in c-jun expression but not c-fos or junB. These results demonstrate that 2'-O-(2-methoxy)ethyl-modified antisense oligonucleotides are 1) effective inhibitors of protein kinase C-alpha expression, and 2) represent a class of antisense oligonucleotide which are much more effective inhibitors of gene expression than the widely used phosphorothioate antisense oligodeoxynucleotides. 相似文献
63.
64.
NA Lisitsyn MV Rosenberg GA Launer LL Wagner VK Potapov TB Kolesnik ED Sverdlov 《Canadian Metallurgical Quarterly》1993,(3):26-29
We describe a novel technique for isolation of sequences that are present in one genome (tracer), but absent in another (driver). Tracer DNA, cleaved with Sau 3A and capped with a single stranded PCR adapter, is allowed to hybridize with an excess of sheared biotinylated driver; biotinylated DNA and its hybrids with the tracer are removed by phenol/chloroform extraction after incubation with streptavidin. After several rounds of subtraction the ends of self-annealed tracer molecules from the nonextractable fraction are filled-in with Tag polymerase and amplified, using the single stranded PCR adapter as a primer. The method has been applied to purification of fragments from a 2.9 kb plasmid added to E. coli DNA at equimolar quantity. Plasmid derived fragments (250-1000 bp), initially comprising 1/1400th part of tracer DNA, were purified to homogeneity after two rounds of subtraction followed by PCR. 相似文献
65.
Ethanol dependence, arising from chronic ethanol exposure, is associated with neuroadaptations of GABAA receptors, evidenced by alterations in various behaviors, receptor responsiveness and subunit gene expression. The present studies explored the effects of ethanol dependence in female rats for comparison with previous studies in our laboratory using male rats. We found that ethanol dependence resulted in differential effects on GABAA receptor gene expression in female rat cerebral cortex compared to ethanol dependent male rats. Notably, chronic ethanol consumption did not change GABAA receptor alpha 1 subunit peptide levels in ethanol dependent female rat cortex, in contrast to previously observed decreases in alpha 1 subunit expression in ethanol dependent male rat cortex. The effects of ethanol dependence on additional GABAA receptor subunit peptide levels (alpha 4, beta 2/3 and gamma 2) were similar, but not identical, between female and male rat cortex. When directly compared within the experiment, male and female rats had similar baseline bicuculline seizure thresholds and displayed a similar increase in seizure susceptibility during ethanol withdrawal. Ethanol withdrawn female rats were cross tolerant to the anticonvulsant effects of diazepam, similar to the findings in ethanol withdrawn male rats. Ethanol withdrawn female rats showed a dose-dependent enhancement of the anticonvulsant effect of the neuroactive steroid, THDOC (3 alpha,21-dihydroxy-5 alpha-pregnan-20-one) compared to control animals. This finding is similar to previous observations of increased sensitivity to the anticonvulsant effect of 3 alpha,5 alpha-THP (3 alpha-hydroxy-5 alpha-pregnan-20-one) in ethanol withdrawn male and female rats. In addition, low dose administration of THDOC elevated seizure thresholds in ethanol withdrawn female but not male rats, suggesting that ethanol withdrawn female rats were more responsive to the anticonvulsant effects of this neurosteroid than were ethanol withdrawn male rats. These findings show that gender impacts on adaptations in GABAA receptors elicited by ethanol dependence. However, the physiological outcomes of the differential alterations are not clear. Taken together, these studies suggest that additional mechanisms, beyond effects on GABAA receptor gene expression are involved in the mediation of ethanol dependence and withdrawal. 相似文献
66.
67.
NV Tat'ianko LL Gromashevskaia AD Vovk MG Kasatkina OV Liashok VI Matiash SP Iasinovy? IaN Kovgan 《Canadian Metallurgical Quarterly》1996,(5-6):119-122
In this paper, characterization is given of clinical and biochemical features of VH B course against the background of narcomania. Recordable in such patient populations are high percentage of delta hepatitis (14.2%), unusual severity of the intoxication syndrome, protracted course with exacerbations (12.2%) and recurrences (8%), outcome being a chronic hepatitis (14.2%), slower normalization of biochemical indicators, persistently low ratio of AIAT activity in diluted and whole blood sera. The persistence of viral markers in drug addicts discharged from the hospital (68%) is fraught with danger of spreading viral hepatitis of prophylactic measures are not strictly observed. 相似文献
68.
LL Ronk 《Canadian Metallurgical Quarterly》1993,24(5):65-67
Traditional roles need not become self-fulfilling prophecies if managers can bridge the gender gap. Feminine, as well as masculine, characteristics can be incorporated into managerial styles to enhance effective leadership. Autonomy, decision-making and assertiveness are as important as nurturing and caring. What are little girls made of? Little girls are made of sugar and spice and everything nice. What are little boys made of? Little boys are made of rats and snails and puppy dog tails. 相似文献
69.
The mitochondrial inner membrane anion channel (IMAC) is a transport pathway which is believed to be involved in mitochondrial volume homeostasis. The protein, however, has not been identified. In this paper, we examine the relationship between IMAC and the adenine nucleotide translocator. Many inhibitors of the adenine nucleotide translocase are shown to block IMAC, including Cibacron blue 3GA, bromcresol green, alizarin red S, agaric acid, palmitoyl-CoA, and the fluorescein derivatives erythrosin B, erythrosin isothiocyanate, rose bengal, and eosin Y. The following evidence suggests that Cibacron blue, agaric acid, and palmitoyl-CoA inhibit by binding to a common site. 1) They all only partially block the transport of small anions such as Cl-, NO3-, and HCO3-, but completely block the transport of larger anions such as malonate. 2) They decrease the IC50 values of each other in a manner consistent with competitive binding. 3) N-Ethylmaleimide decreases their IC50 values by a similar extent. 4) Inhibition by all shows no dependence on matrix pH and only a small dependence on medium pH. It is suggested that these agents may selectively bind to an open state of IMAC and inhibit by decreasing its conductance. The physiological nucleotides CoA, NAD+, NADH, NADP+, NADH, and ATP do not inhibit; in fact, IMAC is shown to transport ATP. Despite these similarities between IMAC and the adenine nucleotide translocase, IMAC appears to be a separate entity, since some of the IC50 values differ by up to 8-fold, and carboxyatracyloside, the most selective inhibitor of the adenine nucleotide translocase, has no effect on IMAC. In addition, IMAC is also able to transport AMP, while the adenine nucleotide translocase does not. 相似文献
70.
The absorption and elimination of [14C]-phenol (63.5 nmol) after oral, dermal, intratracheal, or intravenous administration in rat was rapid and extensive. Urinary elimination of radioactivity predominated, with a range of 75-95% of the dose detected in urine by 72 h post-exposure. Washing the dermal site 72 h post-exposure removed 14% of the dose. Two per cent of the dose was detected in the skin. The urinary metabolites at 4 and 8 h after administration by the four routes included phenyl sulphate and lower amounts of phenyl glucuronide. Phenol was poorly retained in the body after administration by the four routes. Phenol remaining in the body was widely distributed, with accumulation primarily in the liver, lung, and kidney. 相似文献