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941.
A Sarría Chueca MT Martín Nasarre de Letosa B Lomba García LA Moreno Aznar A Lázaro Almarza M Bueno Sánchez 《Canadian Metallurgical Quarterly》1997,47(4):357-362
The production of extracellular beta-amylase by some Bacillus cereus, Bacillus megaterium and Bacillus polymyxa [corrected] strains was investigated, and the maximal yields of the enzyme were 3.6; 9.3 and 20.4 U/mL of the culture fluid, respectively (U, 1 mumol of maltose equivalent per min at 30 degrees C). Several cultivation media were used for beta-amylase production. Bacillus cereus and some strains of Bacillus megaterium gave good yields of beta-amylase only in medium with the addition of nutrient broth. However, beta-amylase produced during growth in protein rich medium (nutrient broth) was highly unstable, probably due to inactivation by proteolytic enzymes co-existing in the culture fluid. Bacillus polymyxa [corrected] strains can produce good yields of beta-amylase on a semi-synthetic medium consisting of inorganic salts, potato starch and inexpensive soybean extract instead of costly peptone and meat extract. The most potential beta-amylase producer was the strain Bacillus polymyxa [corrected] NCIB 8524. The tested Bacillus megaterium and Bacillus polymyxa [corrected] strains were apparently differentiated by temperature cultivation (30 and 37 degrees C) suitable for beta-amylase amylase yield. 相似文献
942.
943.
944.
MA Botella MJ Coleman DE Hughes MT Nishimura JD Jones SC Somerville 《Canadian Metallurgical Quarterly》1997,12(5):1197-1211
Map positions have been determined for 42 non-redundant Arabidopsis expressed sequence tags (ESTs) showing similarity to disease resistance genes (R-ESTs), and for three Pto-like sequences that were amplified with degenerate primers. Employing a PCR-based strategy, yeast artificial chromosome (YAC) clones containing the EST sequences were identified. Since many YACs have been mapped, the locations of the R-ESTs could be inferred from the map positions of the YACs. R-EST clones that exhibited ambiguous map positions were mapped as either cleavable amplifiable polymorphic sequence (CAPS) or restriction fragment length polymorphism (RFLP) markers using F8 (Ler x Col-0) recombinant inbred (RI) lines. In all cases but two, the R-ESTs and Pto-like sequences mapped to single, unique locations. One R-EST and one Pto-like sequence each mapped to two locations. Thus, a total of 47 loci were identified in this study. Several R-ESTs occur in clusters suggesting that they may have arisen via gene duplication events. Interestingly, several R-ESTs map to regions containing genetically defined disease resistance genes. Thus, this collection of mapped R-ESTs may expedite the isolation of disease resistance genes. As the cDNA sequencing projects have identified an estimated 63% of Arabidopsis genes, a very large number of R-ESTs (approximately 95), and by inference disease resistance genes of the leucine-rich repeat-class probably occur in the Arabidopsis genome. 相似文献
945.
NV Shchetinina AN Vernigora MT Gengin NV Firstova 《Canadian Metallurgical Quarterly》1997,69(3):23-28
Phenylmethylsulfonyl fluoride (PMSF)-inhibited carboxypeptidase (CP) is recently described exopeptidase, that cleaved arginine residues from C-terminal of enkephalin synthetic analogs. The highest enzyme activity was found in the adrenal gland and 40% lower one was revealed in the pituitary gland. A 2.5-fold lower than PMSF-inhibited CP activity in adrenal glands was present in testes. The enzyme activity in the brain regions, liver and spleen was about 2.3-fold lower than in the pituitary gland. Its activity in kidneys is insignificant. In the brain region the lowest PMSF-inhibited CP activity was observed in hippocamp and optic and auditory hills, the highest enzyme activity, in the olfactory bulbus and cerebral hemispheres. The differences between brain regions with the highest and the lowest PMSF-inhibited CP activity do not exceed 1.5 fold. The tissue and regional distribution of PMSF-inhibited CP correlated with that for CPH, enzyme of regulatory peptides processing, and it did not correlate with the distribution of lysosomal CPB. The results allow one to suggest the involvement of PMSF-inhibited CP in the processing of the precursors of biological active peptides and secretory proteins. The differences of distribution of PMSF-inhibited CP and CPH are probably connected with involvements of these enzymes in the processing of precursors of different regulatory peptides. 相似文献
946.
Myoglobin has been studied extensively as a paradigm for protein folding. As part of an ongoing study of potential folding initiation sites in myoglobin, we have synthetized a series of peptides covering the entire sequence of sperm whale myoglobin. We report here on the conformation preferences of a series of peptides that cover the region from the A helix to the FG turn. Structural propensities were determined using circular dichroism and nuclear magnetic resonance spectroscopy in aqueous solution, trifluoroethanol, and methanol. Peptides corresponding to helical regions in the native protein, namely the B, C, D, and E helices, populate the alpha region of (phi, psi) space in water solution but show no measurable helix formation except in the presence of trifluoroethanol. The F-helix sequence has a much lower propensity to populate helical conformations even in TFE. Despite several attempts, we were not successful in synthesizing a peptide corresponding to the A-helix region that was soluble in water. A peptide termed the AB domain was constructed spanning the A- and B-helix sequences. The AB domain is not soluble in water, but shows extensive helix formation throughout the peptide when dissolved in methanol, with a break in the helix at a site close to the A-B helix junction in the intact folded myoglobin protein. With the exception of one local preference for a turn conformation stabilized by hydrophobic interactions, the peptides corresponding to turns in the folded protein do not measurably populate beta-turn conformations in water, and the addition of trifluoroethanol does not enhance the formation of either helical or turn structure. In contrast to the series of peptides described here, either studies of peptides from the GH region of myoglobin show a marked tendency to populate helical structures (H), nascent helical structures (G), or turn conformations (GH peptide) in water solution. This region, together with the A-helix and part of the B-helix, has been shown to participate in an early folding intermediate. The complete analysis of conformational properties of isolated myoglobin peptides supports the hypothesis that spontaneous secondary structure formation in local regions of the polypeptide may play an important role in the initiation of protein folding. 相似文献
947.
948.
OBJECTIVES: The aim of this study was to identify factors that contributed to the chronic patient's quality of life from both the patients' and staff's point of view. We were also interested in any lack of congruence between staff and patient perception as these could have significant implications for planning long-term care. METHOD: Fifty of the patients under the Day Release Scheme at View Road Hospital and their staff were given a modified questionnaire concerning the patients' quality of life. RESULTS: Generally the patients reported satisfaction with life domain items covering their living conditions. The majority felt safe in the current setting, enjoyed their work, their regular outings and parole to the nearby shopping centers. Significant differences were observed between the staff and patients' perception in life domain items relating to general well-being, knowledge and education, relationships, in-patient care, leisure and vocational rehabilitation. The staff group perceived having good food, money, good treatment and in employment as being important to their patients' well-being. Patients emphasised having money, family support or a partner, being employed, having time for recreational activities and eating good food. Having good health, medication and feeling at peace were also considered important by many of our patient. CONCLUSIONS: The findings of the study are discussed with regard to implications in planning rehabilitation services and improving the quality of care given to patients. 相似文献
949.
C Schumacher K Paul Y Robbe MT Sicart JL Chanal R Delard JB Dubois 《Canadian Metallurgical Quarterly》1997,52(12):729-731
In mice, in a test of rectal gamma irradiation, cysteamine and cysteine are poor radioprotectors relative to thiazolanes or WR 2721. Among the tested prodrugs, 2-isopropyl 1,3-thiazolane was nearly as efficient as WR 2721 as soon as 15 minutes after its administration. The guarantee of radioprotection is the effective presence of the active aminothiols in the intracellular room during the irradiation. In this study, enterocytes of the rectal mucous membrane were not sufficiently permeable to exogenous cysteine or cysteamine. The cell imperviousness to these straight active aminothiols was compensated by the diffusion of their precursors across the membrane. 相似文献
950.
MD Fraga Fuentes B García Díaz P de Juana Velasco MT Bermejo Vicedo 《Canadian Metallurgical Quarterly》1997,12(6):277-288
Understanding the interaction between foods and antimicrobial agents is an aspect of therapy which may have an important clinical repercussion, which is why it must not be forgotten. This study reviews the interactions of foods with the anti-microbial agents which occur at the level of absorption, considering the mechanisms involved. The food-drug interaction can cause an increase, a decrease, or a delay in the bio-availability of the anti-microbial agents; foods may have no affect on the absorption of the anti-microbial agents, or they may improve the gastrointestinal tolerance. The Food and Drug Administration's bioequivalency criteria for considering whether or not there is an alteration in absorption have an orientative function, as generally all studies are conducted on healthy volunteers, but in clinical practice one must consider the physiological and pathological condition of the patient. The composition of the diet as well as the volume of liquid administered are other aspects which should be considered, as these may exert a different effect depending on the type of drug. After ingesting fatty foods, there is an increased absorption of albendazole, griseofulvin, itraconazole, and mebendazole. All foods but especially carbohydrates reduce the absorption of isoniazide. Among the anti-HIV drugs, the following must be administered on an empty stomach: didanosine, indinavir zalcitabine , and zidovudine ; lamivudine can be administered either on an empty or on a full stomach, because although food delays the absorption, it does not affect the amount absorbed; the absorption of stavudine is not affected by foods; ritonavir should be administered together with tile meals, and saquinavir must be administered after ingestion of food. It is advisable to administer clarithromycin together with foods, and azythromycin on an empty stomach; the same holds true for perfloxacin and rifabutine as for lamivudine. 相似文献