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排序方式: 共有9701条查询结果,搜索用时 15 毫秒
61.
Zhigang Zhu Lise Kristensen Gareth F. Difford Morten Poulsen Samantha J. Noel Waleed Abu Al-Soud Søren J. Sørensen Jan Lassen Peter Løvendahl Ole Højberg 《Journal of dairy science》2018,101(11):9847-9862
In the present study, we hypothesized that the rumen bacterial and archaeal communities would change significantly over the transition period of dairy cows, mainly as an adaptation to the classical use of low-grain prepartum and high-grain postpartum diets. Bacterial 16S rRNA gene amplicon sequencing of rumen samples from 10 primiparous Holstein dairy cows revealed no changes over the transition period in relative abundance of genera such as Ruminococcus, Butyrivibrio, Clostridium, Coprococcus, and Pseudobutyrivibrio. However, other dominant genus-level taxa, such as Prevotella, unclassified Ruminococcaceae, and unclassified Succinivibrionaceae, showed distinct changes in relative abundance from the prepartum to the postpartum period. Overall, we observed individual fluctuation patterns over the transition period for a range of bacterial taxa that, in some cases, were correlated with observed changes in the rumen short-chain fatty acids profile. Combined results from clone library and terminal-restriction fragment length polymorphism (T-RFLP) analyses, targeting the methyl-coenzyme M reductase α-subunit (mcrA) gene, revealed a methanogenic archaeal community dominated by the Methanobacteriales and Methanomassiliicoccales orders, particularly the genera Methanobrevibacter, Methanosphaera, and Methanomassiliicoccus. As observed for the bacterial community, the T-RFLP patterns showed significant shifts in methanogenic community composition over the transition period. Together, the composition of the rumen bacterial and archaeal communities exhibited changes in response to particularly the dietary changes of dairy cows over the transition period. 相似文献
62.
Jan Michniewicz Mieczysaw Jankiewicz 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1988,187(2):102-106
Summary The gelatinized, autoclaved and sodiumhydroxide-treated starch preparations were used and their interaction with soluble pentosans and gliadin was analysed. The molecular sieving technique and optical methods were used to detect the complexes formed. The modified starches formed complexes with both soluble pentosans and gliadin in acidic and neutral media (non-ionic molecular forces being involved). The autoclaved starch showed the highest reactivity. The amylose and amylopectin played different roles in the interactions and the aggregates of amylose with gliadin and amylopectin with soluble pentosans were the prevailing forms present in the complexes. Small quantities of other products were also identified.
Einfluß der hydrothermischen Behandlung auf die physiko-chemischen Eigenschaften des RoggenkornsII. Wechselwirkung der Eiweiß-und Kohlenhydratkomplexe (Modelluntersuchung)
Zusammenfassung Die Wechselwirkungen verkleisterter, autoklavierter und mit Natronlauge behandelter Stärke mit löslichen Pentosanen und Gliadin werden mit Hilfe der Gelpermeation und mit optischen Methoden untersucht. Die modifizierten Stärken bildeten Komplexe mit den Pentosanen und mit Gliadin im sauren und neutralen Medium, autoklavierte Stärke zeigte die hächste Reaktion. Die unterschiedliche Rolle von Amylose und Amylopection zeigte vorherrschend Amylose-Gliadin und Amylopectin-PentosanKomplexe, während andere Komplexe in kleineren Mengen auftraten.相似文献
63.
Jan A. Delcour Sonja Vanhamel Etienne Moerman Roger Vancraenenbroeck 《Journal of the Institute of Brewing》1988,94(6):371-374
When using proanthocyanidin-free materials for the production of beer, a reduction of the wort boiling time can be considered. In worts prepared with regular malt and tannin-free hop extract there is a continuous precipitation of the malt flavanoids while in brews prepared from proanthocyanidin-free malt and regular hops there is a simultaneous extraction and removal of the hop flavanoids leading to constant levels of these hop flavanoids. The results also show that the level of Kjeldahl nitrogen in worts boiled with hops will be the same as that in worts boiled with n-hexane tannin-free hop extracts. These results and the fact that more protein precipitates in brews containing no malt or hop proanthocyanidins suggest that, unlike what is the case during the development of beer haze, polyphenols are not necessary for an effective protein precipitation during wort boiling. 相似文献
64.
JL Beaumont V Beaumont F Jan JC Buxtorf 《Canadian Metallurgical Quarterly》1976,98(44):7057-8, 7061-4, 7067-8
In this review, the clinical reality, the statistical risk, and the frequency of thromboembolism in pill users are evaluated, 6 cases described, and premonitory signs, treatment, and etiology are discussed. Clinically these thromboembolisms appear in unlikely subjects and unusual bodily locations such as the mesenteric veins, without warning. The risks are 8-11 times higher for pulmonary thrombosis, 3-6 times higher for myocardial infarction, based on previously used higher dosed pills. The frequency is about .5-1/1000, or 500-1000/year in France. Some of the cases described used pills with less than .05 mg estrogen, some were heavy smokers, 1 woman died, 1 had a lower extremity amputation, and 1 woman had demonstrated IgG lamda antibodies against ethinyl estradiol. Premonitory signs are rare, and unsually ignored. The immediate action is to stop the pill and start anticoagulants. The cause of these disorders is not known in detail, but is presumed to be estrogens, therefore, low-dose pills, i.e., those with .05 or .03 mg ethinyl estradiol, should be used if possible. Other risk factors are surgery, age, immobilization, history of vein disorders, smoking, hyperlipidemia, hypertension, especially since the pill potentiates hypertension, hyperlipidemia, and hypercoagulation. Some mechanisms proposed are hyperlipidemia, disturbed blood coagulation factors, decreased fibrinolysis, alterations in the blood vessel endothelium and immunity against the estrogen in the pill. 相似文献
65.
66.
Wang Z Yang C Fingas M Hollebone B Peng X Hansen AB Christensen JH 《Environmental science & technology》2005,39(22):8700-8707
Biomarkers have become increasingly important for identifying the source of spilled oil, due to their specificity and high resistance to biodegradation. The biomarkers most commonly used in forensic investigations are the high molecular weight (MW) tri- and pentacyclic terpanes and steranes. For lighter petroleum products such as jet fuels and diesels, the refining processes remove most high MW biomarkers from the original crude oil feedstock. The smaller bicyclic sesquiterpanes, however, are concentrated in these products. Sesquiterpanes are ubiquitous components of crude oils and ancient sediments. Examination of GC-MS chromatograms of these bicyclic biomarkers using their characteristic fragment ions (m/z 123, 179, 193, and 207) provides a highly diagnostic means for identifying spilled oil, particularly for lighter refined product samples that are difficult to identify by current techniques. In this work, sesquiterpanes in crude oils and petroleum products are identified and characterized, distributions of sesquiterpanes in oils and refined products are compared, the effects of evaporative weathering on sesquiterpane distributions are examined, and a methodology using diagnostic indices of sesquiterpanes is developed for oil correlation and differentiation. Finally, two case studies are presented to illustrate the unique utility of sesquiterpanes for fingerprinting and identifying unknown diesel spills. 相似文献
67.
FJ Cousin S Louesdon MB Maillard S Parayre H Falentin SM Deutsch G Boudry G Jan 《Food microbiology》2012,32(1):135-146
Dairy propionibacteria display probiotic properties which require high populations of live and metabolically active propionibacteria in the colon. In this context, the probiotic vector determines probiotic efficiency. Fermented dairy products protect propionibacteria against digestive stresses and generally contain a complex mixture of lactic and propionic acid bacteria. This does not allow the identification of dairy propionibacteria specific beneficial effects. The aim of this study was to develop a dairy product exclusively fermented by dairy propionibacteria. As they grow poorly in milk, we determined their nutritional requirements concerning carbon and nitrogen by supplementing milk ultrafiltrate (UF) with different concentrations of lactate and casein hydrolysate. Milk or UF supplemented with 50 mM lactate and 5 g L−1 casein hydrolysate allowed growth of all dairy propionibacteria studied. In these new fermented dairy products, dairy propionibacteria remained viable and stress-tolerant in vitro during minimum 15 days at 4 °C. The efficiency of milk fermented by the most tolerant Propionibacterium freudenreichii strain was evaluated in piglets. Viability and SCFA content in the colon evidenced survival and metabolic activity of P. freudenreichii. This work results in the design of a new food grade vector, which will allow preclinical and clinical trials. 相似文献
68.
69.
Wasan Duangkhamchan Adisak Phomphai Ruchuon Wanna Lamul Wiset Juckamas Laohavanich Frederik Ronsse Jan G. Pieters 《Food and Bioprocess Technology》2017,10(2):284-295
Infrared (IR) heating method against rice weevils (Sitophilus oryzae) in an egg stage was investigated. A kinetic model was developed to describe insect mortality in a temperature range of 40–60 °C. Effects of IR heating temperature (50–60 °C) and exposure time (1–3 min) on insect mortality and quality attributes of the treated rice were evaluated. The optimized condition obtained by means of the response surface method was used to analyze rice quality before and after IR treatment with storage. The results showed that the 0.5th-order thermal death kinetic equation was the most suitable model, and the S. oryzae eggs had less heat tolerance than the adults and some other species. Mortality achieved 100 % after 2 min for all temperatures. Both IR heating parameters significantly affected the treated milled rice qualities. The minimal changes in rice quality before and after storage could be obtained using optimized temperature and exposure time of 53.6 °C and 1.2 min, respectively. 相似文献
70.