全文获取类型
收费全文 | 2268篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 8篇 |
金属工艺 | 1篇 |
建筑科学 | 3篇 |
矿业工程 | 1篇 |
轻工业 | 10篇 |
无线电 | 5篇 |
一般工业技术 | 2篇 |
冶金工业 | 2238篇 |
自动化技术 | 2篇 |
出版年
2023年 | 1篇 |
2020年 | 1篇 |
2013年 | 1篇 |
2011年 | 4篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 70篇 |
1998年 | 737篇 |
1997年 | 371篇 |
1996年 | 267篇 |
1995年 | 131篇 |
1994年 | 112篇 |
1993年 | 120篇 |
1992年 | 19篇 |
1991年 | 28篇 |
1990年 | 18篇 |
1989年 | 21篇 |
1988年 | 19篇 |
1987年 | 21篇 |
1986年 | 15篇 |
1985年 | 16篇 |
1983年 | 3篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 17篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 67篇 |
1976年 | 160篇 |
1975年 | 3篇 |
1964年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有2270条查询结果,搜索用时 15 毫秒
1.
2.
3.
W Guo RS Lovell YH Zhang BL Huang TP Burris WJ Craigen ER McCabe 《Canadian Metallurgical Quarterly》1996,178(1-2):31-34
We cloned the murine full-length cDNA encoding Ahch, the mouse homologue of DAX1 (DSS-AHC Region on Human X Chromosome, Gene1) which is the gene responsible for human X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH). Sequence analysis revealed that the murine and human cDNAs have 65% aa identity and 75% aa similarity overall. The cysteine residues in the putative DNA binding domain, which may interact with Zn2+ ions to form zinc fingers, are 100% conserved between the two species, indicating that the novel zinc-finger structures in DAX1 may be functional. In addition, mouse interspecific backcrosses show that the Ahch gene is closely linked to the glycerol kinase locus, GyK, on the mouse X chromosome, indicating that the order of the loci is conserved in this syntenic region between mouse and human. 相似文献
4.
WJ Cho EK Kim MJ Park SU Choi CO Lee SH Cheon BG Choi BH Chung 《Canadian Metallurgical Quarterly》1998,6(12):2449-2458
In this study a series of 3-arylisoquinoline derivatives were synthesized and cytotoxicity against human melanoma tumor cell evaluated, and a three dimensional quantitative structure-activity relationship was investigated using the comparative molecular field analysis (CoMFA). The results suggested that the electrostatic, steric and hydrophobic factors of 3-arylisoquinolines were strongly correlated with the antitumor activity. Considerable predictive ability (cross-validated r2 as high as 0.721) was obtained through CoMFA. 相似文献
5.
Peripheral blood lymphocytes from two human donors with elevated serum IgE concentrations were maintained in short term tissue culture preparations. Repeated culture preparations demonstrated that IgE was produced in vitro in amounts that could be measured by the double antibody radioimmunoassay technique. The amount of IgE produced by replicate cultures of cells from a single bleeding of the donor was similar when the cultures were simultaneously prepared. In contrast, IgE production by the same donor's lymphocytes varied when the culture preparations were initiated from separate bleedings. The results of simultaneous cultures of a single bleeding were sufficiently consistent to provide a means of testing the effect of pharmacologic agents on the in vitro production of IgE. Cholera toxin effected a marked reduction in production of IgE by lymphocytes of both cell donors. Isoproterenol showed marked inhibition of IgE production at 10(-3) M but cell viability studies suggested that this may have been due to decreased cell viability. At lower, nontoxic concentrations of isoproterenol (10(-4) M-10(-6) M) slight but definite inhibition of in vitro IgE production was evident. This inhibition was more pronounced subsequent to the first 24 hr of exposure of the cells to isoproterenol. 相似文献
6.
It has been demonstrated that low concentrations of basic lipophilic drugs in biological fluids may be extracted and concentrated 10(4)-10(6) times by a series of extraction procedures in which the ratio of the extracting solvent to that of the solution to be extracted is of the order of 1:100 (microphase extraction procedure). Typically, basic drugs (atropine, aminopentamide, hyoscine, chloroquine, pyrimethamine) were extracted and concentrated sufficiently for direct GC analysis from 24-hour urine samples by a procedure involving three simple consecutive extraction steps. Using this procedure, it was demonstrated that after administration of aminopentamide (300 micrograms) to patients in the form of anti-diarrhoeal tablets, measurable quantities of the free, unchanged drug can be demonstrated in 24-hour urine samples. The main advantages of the method are simplicity, rapidity and sensitivity due to the low background interference in the GC separations. The principle involved can be extended to the analysis of acidic drugs with suitable solubility properties. 相似文献
7.
8.
T Barkas SF AL-Khateeb WJ Irvine NM Davidson P Roscoe 《Canadian Metallurgical Quarterly》1976,25(2):270-279
Circulating immune complexes in the sera of patients with thyroid disorders or bronchogenic carcinoma were investigated using an assay system based on the inhibition of the ADCC activity of rat spleen cells. Increased inhibition, as compared with that of the sera of age and sex matched controls, was found in patients with thashimoto thyroiditis, primary hypothyroidism and bronchogenic carcinoma. The degree of inhibition in the first two groups was markedly increased compared with control sera of the same IgG content. However, the results in the lung cancer group were slightly but not significantly greater than in controls with the same level of IgG. Increased IgG levels were found in patients with thashimoto thyroiditis and thyrotoxicosis, and also in patients with bronchogenic carcinoma who had mediastinal gland involvement. The lower level of sensitivity of the assay system was approximately 600 ng added aggregated IgG, corresponding to a concentration of 6mu g/ml in the sample assayed. It is possible that circulating immune complexes may exist in lung cancer, but at a level below that of the present assay system. 相似文献
9.
We found that it was nearly impossible to apply the quinoline-carbamate aphicide per os by means of synthetic diets, owing to its high feeding-deterrent-effect. After application via the roots of the host plant, this systemic compound is deposited on the leaf surface. The results suggest that the toxic effect is not the result of the oral uptake of phloem sap, but of the tarsal contact with the toxicant. Sensitivity of aphids to this compound and LD50-values were determined after topical applications. 相似文献
10.
Mutant strains of Rhizobium japonicum that were unable to allow the Corsoy cultivar of soybean to reduce acetylene or fix N2 were isolated. These strains grow as well as the wild type in a variety of media. Mutant strains SM1 and SM2 did not form nodules on the host plant; however, they reduced acetylene in the nonsymbiotic assay. Strains SM3 and SM4 produced nodules that did not have the characteristic pink pigment caused by leghemoglobin. The nodules formed by these strains also were small. One mutant strain, SM5, produced large pink nodules. The lesion in this strain seems to be in the gene that specifies nitrogenase component II. 相似文献