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排序方式: 共有480条查询结果,搜索用时 15 毫秒
71.
There is strong evidence that chronic heart chronic heart failure (CHF) impairs skeletal muscle function independent of blood flow and bulk O2 delivery. Purpose: This investigation sought to determine whether alterations in muscle capillary geometry and surface area that are thought to be primary determinants of the efficacy for blood-tissue 02 exchange might be altered in CHF and contribute to these changes. Methods: Plantaris (fast twitch) and soleus (slow twitch) muscles from control (C) and 6- to 7-wk post myocardial infarcted (CHF) rates were perfusion-fixed in situ. These muscles were analyzed using morphometric techniques that facilitated determination of muscle sarcomere length fiber cross-sectional area, capillary tortuosity and branching coefficient (c(K,0)), capillary length, volume, and surface area. Results: Normalized to a sarcomere length of 2.1 microns, plantaris fiber cross-sectional area decreased by 21% (P < 0.05), and capillary-to-fiber ratio decreased from 2.05 +2- 0.07 in C to 1.79 +2- 0.04 (P < 0.05) in CHF, but these variables were unchanged in soleus. These was no change in c(K,0) or capillary diameter in either muscle, and thus capillary length and surface area per fiber volume remained unchanged. From the measured fiber atrophy and capillary involution in plantaris reductions of total muscle capillary length, volume, and surface area of 11%, 9% and 17%, respectively, are estimated. Conclusion: These changes, coupled with reduced blood flow may impair the effective matching of muscle fiber 02 delivery to 02 requirement during repeated muscle contractions (i.e. exercise). The scenario is expected to reduce intramyocyte 02 partial pressure and thereby contribute to the greater fatigability characteristic of the CHF condition. 相似文献
72.
A O Tamm 《Die Nahrung》1984,28(6-7):711-715
In order to answer up to now open questions regarding the role of the microflora in the pathophysiology of adult coeliac disease the excretion of bacterial metabolites in urine has been followed. Unusual high outputs of p-cresol and/or phenol were found in almost all patient, whereas an increased excretion of indican could be observed in a few persons, only. The response to short-term antibacterial therapy was variable. 相似文献
73.
Effects of high concentrations of lithium, cesium and ammonium chlorides on the reaction ability of free CMP and cytosine in free DNA of CD phage with respect to O-methylhydroxylamine (OMHA) are studied. CMP reaction in all the cases takes place mainly for 24 hours. Like classical B-form, native DNA, having C-form in high ionic strength solution (as estimated from circular dichroism data), is not modificated. Thus, the access of some cytosine residues in intraphage DNA to OMHA is due not to the decreased DNA hydratation in situ, but to the presence of differently ordered regions in DNA. 相似文献
74.
Fibroblasts growth synthesis activities appear to be under exquisite control. This control is mediated in part by substances present in blood plasma or released by other cells. We have studied the role of peripheral blood mononuclear cells (PBM) activated with phytohemagglutinin-P (PHA) on DNA synthesis, proliferation, and the cell cycle of human diploid fibroblasts. Culture medium from activated but not from unactivated PBM cultures inhibited fibroblast DNA synthesis and growth in a dose-dependent manner. The activity, which was designated as lymphocyte factor (LF), was very potent; it inhibited 50% of the DNA synthesis and cell growth at a dilution of 1:160. It has a molecular weight between 50,000 and 100,000 daltons and it is destroyed by trypsin digestion or by heating at 80 degrees C for 30 minutes. The activity was not due to the presence of prostaglandin. Furthermore, using immunoprecipitation and affinity chromatography, it was shown conclusively to to be distinctly different from alpha lymphotoxin (alpha-LT). It was not cytotoxic, as shown by the 51chromium release technique. Using flow microfluorimetry it was shown that the activity regulates fibroblast growth by preventing quiescent cells in the G0 or G1 stage of the cell cycle from entering the S phase. Cells already in S at the time of exposure complete DNA synthesis but cannot divide, and they accumulate in G2. The activity also has marked effects on protein synthesis. Activated mononuclear cells may play a major role in regulating fibroblast growth and synthesis in normally healing wounds and in acute and chronic inflammatory processes. 相似文献
75.
Effects of some phenols and polycyclic aromatic hydrocarbon derivatives on benz(a)-pyrene metabolism have been studied in the microsomal system isolated from the mouse embryonic cell cultures. The rate of benz(a)pyrene metabolism was shown to depend on the structure and concentration of the agents added. The toxic effect of benz(a)pyrene was summed up with that of either agent studied (except ionol) added simultaneously to the cell culture. 相似文献
76.
B. Tamm 《Automatica》1977,13(3):323-324
77.
78.
Epidemiologic studies of time to some failure often show a quadratic relation between the risk of failure and covariate(s). We study the nadir for a given covariate, i.e., the value of the covariate associated with the lowest risk (supposing a U-shape), within Aalen's additive risk model. This model was applied since the effect of the covariate(s) is allowed to vary over time and, as a consequence, a given nadir can vary over time. We propose a test for the null hypothesis that the nadir is time independent and, if this is the case, an estimate of the nadir. Large sample properties of the test statistic and estimator are derived. The methods are illustrated with data where time to death is related to body mass index. 相似文献
79.
Mutations in the myocilin (MYOC), also known as Trabecular meshwork-Inducible Glucocorticoid Response (TIGR) gene can lead to juvenile open-angle glaucoma in human and may be responsible for at least 3% of primary open-angle glaucoma. To develop a mouse model of primary open angle glaucoma, and to get deeper insight into the mechanisms of the MYOC/TIGR gene regulation and function, we have isolated and characterized full size mouse Myoc/Tigr cDNA and genomic clones. The mouse and human MYOC/TIGR genes have the same exon-intron structure and contain 3 exons, although the mouse gene is 6 kb shorter than the human gene (10 kb versus 16 kb) due to differences in the length of introns. The MYOC/TIGR gene encodes a moderately conserved protein, which is 82% identical between human and mouse. The encoded protein is 14 amino acids shorter at the N-terminus in the mouse than in the human (490 versus 504 amino acids). Mouse and human MYOC/TIGR genes show a similar pattern of expression in adult ocular and nonocular tissues. The mouse Myoc/Tigr gene was mapped to Chromosome 1 at position 82.8 cM from the centromere. All residues, which were identified in the human MYOC/TIGR protein as critical for glaucoma development, are conserved in the mouse Myoc/Tigr. 相似文献
80.