全文获取类型
收费全文 | 1983篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 20篇 |
金属工艺 | 1篇 |
机械仪表 | 3篇 |
建筑科学 | 1篇 |
轻工业 | 21篇 |
一般工业技术 | 10篇 |
冶金工业 | 1918篇 |
原子能技术 | 1篇 |
自动化技术 | 9篇 |
出版年
2022年 | 1篇 |
2015年 | 1篇 |
2013年 | 8篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 49篇 |
1998年 | 582篇 |
1997年 | 307篇 |
1996年 | 244篇 |
1995年 | 149篇 |
1994年 | 105篇 |
1993年 | 106篇 |
1992年 | 19篇 |
1991年 | 39篇 |
1990年 | 36篇 |
1989年 | 18篇 |
1988年 | 26篇 |
1987年 | 31篇 |
1986年 | 27篇 |
1985年 | 34篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1978年 | 4篇 |
1977年 | 27篇 |
1976年 | 104篇 |
1975年 | 6篇 |
1955年 | 1篇 |
排序方式: 共有1984条查询结果,搜索用时 15 毫秒
71.
SE Santos AK Ribeiro-Dos-Santos JF Guerreiro EJ Santos TA Weimer SM Callegari-Jacques MA Mestriner MH Franco MH Hutz FM Salzano 《Canadian Metallurgical Quarterly》1998,25(6):505-522
A total of 732 individuals affiliated with six Amazonian Indian populations were variously studied in relation to 26 protein genetic systems. Eleven of them were found to be monomorphic in these groups, in accordance with previous investigations. Similarities and dissimilarities (the latter involving the Rh, Duffy, haptoglobin and transferrin systems) were observed in relation to earlier investigations in four of these populations (Galibi, Palikour, Mundurucu and Tenharim). A dimeric, cathodal variant of albumin was found among two Galibi subjects, and the fairly common occurrence of CP* ACAY among some South American Indian populations was confirmed. The results in the six populations were compared with those from 29 others. When relationships are searched for among tribes of the same linguistic group, the factor that seems to be most influential is geographical localization, an exception being the pattern observed among the Cayapo subgroups. The latter shows genetic differences of the same level of magnitude as those observed among Ge-speaking tribes. 相似文献
72.
Cleavage motifs of the yeast 20S proteasome beta subunits deduced from digests of enolase 1 总被引:3,自引:0,他引:3
AK Nussbaum TP Dick W Keilholz M Schirle S Stevanovi? K Dietz W Heinemeyer M Groll DH Wolf R Huber HG Rammensee H Schild 《Canadian Metallurgical Quarterly》1998,95(21):12504-12509
The 436-amino acid protein enolase 1 from yeast was degraded in vitro by purified wild-type and mutant yeast 20S proteasome particles. Analysis of the cleavage products at different times revealed a processive degradation mechanism and a length distribution of fragments ranging from 3 to 25 amino acids with an average length of 7 to 8 amino acids. Surprisingly, the average fragment length was very similar between wild-type and mutant 20S proteasomes with reduced numbers of active sites. This implies that the fragment length is not influenced by the distance between the active sites, as previously postulated. A detailed analysis of the cleavages also allowed the identification of certain amino acid characteristics in positions flanking the cleavage site that guide the selection of the P1 residues by the three active beta subunits. Because yeast and mammalian proteasomes are highly homologous, similar cleavage motifs might be used by mammalian proteasomes. Therefore, our data provide a basis for predicting proteasomal degradation products from which peptides are sampled by major histocompatibility complex class I molecules for presentation to cytotoxic T cells. 相似文献
73.
74.
5-Aminosalicylic acid conjugate of ursodeoxycholic acid was synthesized in above 90% yield by adding a basic solution of 5-aminosalicylic acid into the mixed anhydride formed with ursodeoxycholic acid and ethyl chloroformate. The 5-aminosalicylic acid conjugate of ursodeoxycholic acid was poorly secreted into the bile and was deconjugated with cholylglycine hydrolase and Clostridium perfringens, that deconjugate naturally occurring glycine and taurine conjugates of bile acids. However, ursodeoxycholic acid 5-aminosalicylic acid conjugate was not absorbed from the duodenum but was concentrated in the colon where it was partially hydrolyzed by the intestinal bacteria to ursodeoxycholic acid and 5-aminosalicylic acid. We believe that this unique conjugation of ursodeoxycholic acid with 5-aminosalicylic acid may facilitate the transport of both 5-aminosalicylic acid and ursodeoxycholic acid to the colon and may be useful for the treatment of colonic inflammatory bowel diseases, ulcerative colitis and Crohn's disease. 相似文献
75.
U Hammerling E Bongcam-Rudloff N Setterblad R Kroon AK Rehnstr?m E Viitanen G Andersson L Sj?din 《Canadian Metallurgical Quarterly》1998,18(7):451-460
Cells of a human glioblastoma line were stably transfected with a glial fibrillary acidic protein (GFAP) promoter sequence/lacZ reporter gene. Following this modification, they produced Escherichia coli beta-galactosidase constitutively in amounts that could be measured through their conversion of an added fluorophore into a product readily estimated by fluorimetry. Human interferons (IFN) selectively and in a dose-dependent manner reduce the formation of beta-galactosidase in this system. We have used it as the basis for a novel assay that is sensitive (4-40 pg/ml), precise, completed in 30 h, and applicable to both type I and type II human IFNs. Statistical analysis showed interassay relative standard deviations ranging from 5% to 11%, and most individual assays revealed potencies with limits of error within 85%-115%. Neither partially trypsin-digested IFN nor the other cytokines and mitogens we tested reacted in this system, except for tumor necrosis factor-alpha (TNF-alpha). The high selectivity was further shown by the loss of response to IFN in the presence of the appropriate specific anti-IFN or anti-IFN-gamma receptor antibodies. 相似文献
76.
WH Kahr A Al-Homadhi J Meharchand DJ Bailey AK Stewart 《Canadian Metallurgical Quarterly》1998,28(3-4):437-442
We present a case of a 55 year old man with multiple myeloma who underwent autologous stem cell transplantation and subsequently developed testicular myeloma. Testicular enlargement was observed only after treatment of an incidental prostatic adenocarcinoma with chemical orchidectomy at a time when myeloma was controlled systemically. A subsequent bilateral surgical orchiectomy revealed plasmacytoma in both testis. Enhanced production of B-lymphocytes after castration has been reported and implicates testosterone as a possible negative regulator of B-cell production. We propose that the androgen deficient state may have contributed to the development of plasmacytoma of the testes in our patient. The regulatory role of sex steroids in B-cell development is discussed. 相似文献
77.
78.
79.
We present an epidemiological model applicable to insulin-dependent diabetes mellitus (IDDM), based on which prevalence rates are estimated from assumed rates of incidence and mortality of diabetes. The model is illustrated by analysing epidemiological data on IDDM in Fyn County, Denmark for the period 1970-1990, with predictions of prevalence rates during 1990-2020. The epidemiological model assumes known prevalence rates as well as incidence rates and mortality at a given point of time. Under assumed rates of incidence and mortality of IDDM and its complications, the prevalence rate is the dependent variable which is estimated as a function of calendar time. We used epidemiological data on IDDM (operationally defined as insulin-treated diabetes with onset before age 30 years), blindness and nephropathy as well as mortality as reported for the years 1973 and 1987 in Fyn County, Denmark. During 1970-1990 the prevalence of IDDM increased steadily, due to increasing incidence and decreasing risk of complications and mortality. The relative prevalence of patients with nephropathy increased whereas that of blind patients decreased considerably. Under specified assumptions regarding the future levels of incidence of disease, complications and of mortality, it is estimated that the prevalence rate of IDDM in the year 2020 will be 45-60% higher than the level in 1990. The relative prevalence of patients with nephropathy will increase further, whereas the relative prevalence of blind patients will remain constant at a low level. We conclude that IDDM will represent an increasing public health problem in Denmark over the next decades, with increasing overall prevalence rates and a rising proportion of patients with nephropathy. The major determinants of this trend are increasing incidence, combined with declining mortality and declining risk of complications. It is recommended that epidemiological modelling techniques be further developed to provide improved data for the planning of the future diabetes care. 相似文献
80.