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71.
Cytolytic antibodies to murine lymphomas elicited by immunization with allogenic and syngenic tumors
Five quaternary ammonium germicides (QAGs) were tested for their adsorption by agar. This was found to be in the following ascending order: alkylbenzylmethyl-ammonium chloride, alkyltrimethylammonium bromide, cetyltrimethylammonium bromide, cetylpyrimidinium chloride and cetylbenzyldimethylammonium chloride. An inverse relationship was established between the extent of agar binding of the QAGs and their inhibition zones. In an attempt to develop a sensitive cup-plate assaying technique suitable for QAGs, important factors affecting the agar-diffusion of QAGs were investigated. These included the influence of various polysorbates, buffer ions, agars and test organisms. Furthermore, the effect of the pH and/or the concentration of the selected polysorbate and the buffer were studied. The best medium developed for the sensitive agar-diffusion assay of QAGs was nutrient agar-Tris (0.05 M, pH 8) provided that distilled water and polysorbate 20 (0.5%) were used as diluents for the mixed alkyl and the pure cetyl QAGs, respectively. 相似文献
72.
Experimental colitis 总被引:1,自引:0,他引:1
Ulcerative colitis and Crohn's disease are complex, problematic diseases of unknown etiology in man, and appropriate experimental models would be useful in elucidating their pathogenesis and treatment. Although there have been numerous attempts to produce inflammatory ulcerative colonic disease in laboratory animals resembling those human disease forms, none has been entirely successful. Investigators have conducted experiments involving almost every etiological factor suggested for initiation of these diseases. The methods reviewed in this paper include production of experimental colitis by vascular impairment, and immunological methods such as bacterial infection, allergic reactions, direct and indirect hypersensitivity reactions, as well as autoimmune mechanisms. The results of carrageenan-induced colitis, irradiation, dietary, and drug-induced techniques are also discussed and the frequency and nature of spontaneous colonic lesions in animals is summarized. 相似文献
73.
Organ specificity of angiotensin II and Des-aspartyl angiotensin II in the conscious rat 总被引:2,自引:0,他引:2
Des-Asp angiotensin II (des-Asp AII) is a naturally occurring heptapeptide metabolite of angiotensin II (AII) which is formed by the enzymatic action of aminopeptidase A. Angiotensin II and des-Asp AII were infused into unanesthetized rats while direct mean arterial pressure, serum aldosterone and serum corticosterone were measured. Both AII and des-Asp AII caused a dose-related increase in serum aldosterone with a significant increase occurring with a dose as low as 1 ng/min. This effect was blocked by pretreatment with 1-Sar-8-Ala-angiotensin II, a competitive inhibitor of AII; however, the inhibitor was more effective in blocking the effects of AII (101%) than of des-Asp AII (82%). Both angiotensins induced a dose-related increase in serum corticosterone and mean arterial pressure. Des-Asp AII was however only 1/10 as potent as AII in elevating mean arterial pressure. 1-Sar-8-Ala-AII was also effective in inhibiting the pressor effects of AII and des-Asp AII. These data illustrate a high degree of organ specificity or selectivity for des-Asp AII and a low specificity for AII. Aminopeptidase A and leucine aminopeptidase were identified in the adrenal cortex and medulla in large amounts. Des-Asp AII may thus be formed from AII locally in the adrenal gland prior to exerting its action at that site. 相似文献
74.
An acromegalic patient with galactorrhea-amenorrhea who conceived following long-term 2-bromo-alpha-ergocryptine (CB-154) therapy is described. During CB-154 therapy, determinations of serum prolactin (PRL), luteinizing hormone (LH)-human chorionic gonadotropin, follicle-stimulating hormone a reduction in PRL level followed by an LH peak, a rise in basal body temperature and menstruation. The patient became pregnant during the next cycle, but therapeutic abortion was performed because of the active acromegaly. These results demonstrate that CB-154 can restore ovulatory function not only to the patient with a hypothalamic disorder but also to the acromegalic patient with an enlarged sella turcica. 相似文献
75.
Michaela Fox Mike Mitchell Moira Dean Christopher Elliott Katrina Campbell 《Food Security》2018,10(4):939-963
Food fraud is an intentional act for economic gain. It poses a risk to food integrity, the economy, public health and consumers’ ethics. Seafood is one commodity which has endured extensive fraudulent activity owing to its increasing consumer demand, resource limitations, high value and complex supply chains. It is essential that these fraudulent opportunities are revealed, the risk is evaluated and countermeasures for mitigation are assigned. This can be achieved through mapping of the seafood supply chains and identifying the vulnerability analysis critical control points (VACCP), which can be exposed, infiltrated and exploited for fraudulent activity. This research systematically maps the seafood supply chain for three key commodities: finfish, shellfish and crustaceans in the United Kingdom. Each chain is comprised of multiple stakeholders across numerous countries producing a diverse range of products distributed globally. For each supply chain the prospect of fraud, with reference to species substitution, fishery substitution, illegal, unreported and unregulated substitution, species adulteration, chain of custody abuse, catch method fraud, undeclared product extension, modern day slavery and animal welfare, has been identified and evaluated. This mapping of the fraudulent opportunities within the supply chains provides a foundation to rank known and emerging risks and to develop a proactive mitigation plan which assigns control measures and responsibility where vulnerabilities exist. Further intelligence gathering and management of VACCPs of the seafood supply chains may deter currently unknown or unexposed fraudulent opportunities. 相似文献
76.
Norbixin is the primary carotenoid in annatto coloring, which imparts the desired orange color in Cheddar cheese. However, a portion of the colorant remains in the cheese whey and is undesirable; therefore, a bleaching step is often applied. Restrictions exist for norbixin concentrations in products destined for infant formula. As such, evaluation of norbixin concentrations in whey and whey ingredients is desirable. Current extraction methods are laborious and require solvents that are banned in many countries. The objective of this study was to develop a fast and inexpensive norbixin extraction and quantitation technique using approved solvents with similar sensitivity to current established methods. Instead of solvent extraction and column purification, acetonitrile was added directly to fluid wheys, retentates, and rehydrated whey protein concentrates. An isocratic mobile phase [70% acetonitrile and 30% water with 0.1% (wt/vol) formic acid] was used and, to increase sensitivity, a large volume (50 μL) was injected onto the column. The column used was a C18 column with a particle size of 2.6 μm and column length of 10 cm. The column inner diameter was 4.6 mm and the pore size was 100 ?. All of the previously described conditions allowed the run time to be only 4 min. The sample was sent through a photodiode array detector and quantified at 482 nm. Norbixin was quantified using external standard curves. The developed method had a >90% norbixin recovery in both milk and whey (9.39 μg/L–2.35 mg/L). The limit of detection of norbixin in fluid whey was 2.7 μg/kg and the limit of quantitation was 3.5 μg/kg, both of which are significantly lower than in previously described methods. The extracts were stable over 30 min at 21°C and stable over 24 h at 4°C. Repeatability and precision of the method had relative standard deviations of less than 13%. The developed method provides time and cost savings for evaluation of norbixin concentration in whey and whey products. 相似文献
77.
Boxes of beef were examined when product was packed and when boxes were loaded out of five packing plants, when boxes were loaded into and loaded out of seven refrigerated warehouses, and when boxes were received and opened at 21 retail stores. At each stage of handling at each facility, the boxes to be examined were selected at random. For each selected box, the temperature of product at the centre of the box was measured, and the date of packing and the plant of origin were noted. When cuts were packed, the minimum, median and maximum temperatures were about 2, 6 and 18 °C, respectively. Temperatures were successively lower when boxes were loaded out of packing plants, into warehouses and out of warehouses. When loaded out of warehouses, the minimum, median and maximum temperatures were about −2, 1 and 8 °C, respectively. The ranges of temperatures were similar, but the median temperatures were about 2 or 1.5 °C, respectively, when boxes were received at or were opened at retail stores. At packing plants and warehouses, the temperatures of manufacturing and ground beef were lower than those of cuts, but at the retail store the temperatures of all types of product were similar. When boxes were opened at retail stores, the minimum, median and maximum ages of cuts were about 2, 20 and 130 days, respectively; and the corresponding ages for manufacturing and ground beef were 2, 7 and 56 days, respectively. The data indicate that boxed beef is generally cooled to and maintained at temperatures within the range sought by the meat industry. However, cooling to chiller temperatures of product that is packed while warm can take several days; and some product is held for times that are excessive in view of the temperatures of boxed beef. 相似文献
78.
Lofts S Chapan PM Dwyer R McLaughlin MJ Choeters I Sheppard SC Adams WJ Alloway BJ Antunes PM Campbell PG Davies B Degryse F De Vries W Farley K Garrett RG Green A Jan Groenenberg B Hale B Harrass M Hendershot WH Keller A Lanno R Liang T Liu WX Ma Y Menzie C Moolenaar SW Piatkiewicz W Reimann C Rieuwerts JS Santore RC Sauvé S Schuetze G Schlekat C Skeaff J Smolders E Tao S Wilkins J Zhao FJ 《Environmental science & technology》2007,41(18):6326-6331
79.
用精确饲喂技术评价了 3个品种的中国双低油菜和 1个加拿大卡诺拉的脱脂种籽和商品饼粕的能量和氨基酸的有效性。结果表明 ,4个脱脂种籽的氮校正真代谢能和氨基酸真消化率没有差异 (P >0 .0 5 ) ;而 4个商品饼粕的脱脂样品的氮校正真代谢能和氨基酸真消化率有极显著或显著差异。研究结果证实 ,不适当的加工方式不仅降低了氨基酸的有效性 ,而且影响家禽对能量的利用效率。 相似文献
80.