全文获取类型
收费全文 | 82929篇 |
免费 | 1912篇 |
国内免费 | 46篇 |
出版年
2018年 | 890篇 |
2017年 | 1071篇 |
2016年 | 2795篇 |
2015年 | 6131篇 |
2014年 | 5727篇 |
2013年 | 5451篇 |
2012年 | 4640篇 |
2011年 | 1885篇 |
2010年 | 2007篇 |
2009年 | 1994篇 |
2008年 | 491篇 |
2007年 | 454篇 |
2006年 | 501篇 |
2005年 | 6588篇 |
2004年 | 5289篇 |
2003年 | 3499篇 |
2002年 | 1086篇 |
2001年 | 1085篇 |
2000年 | 312篇 |
1999年 | 1462篇 |
1998年 | 322篇 |
1997年 | 170篇 |
1992年 | 1923篇 |
1991年 | 2011篇 |
1990年 | 2077篇 |
1989年 | 2001篇 |
1988年 | 1956篇 |
1987年 | 1814篇 |
1986年 | 1628篇 |
1985年 | 1653篇 |
1984年 | 1087篇 |
1983年 | 833篇 |
1982年 | 458篇 |
1981年 | 421篇 |
1980年 | 369篇 |
1979年 | 1074篇 |
1978年 | 759篇 |
1977年 | 607篇 |
1976年 | 629篇 |
1975年 | 872篇 |
1974年 | 994篇 |
1973年 | 1005篇 |
1972年 | 953篇 |
1971年 | 931篇 |
1970年 | 820篇 |
1969年 | 830篇 |
1968年 | 735篇 |
1967年 | 752篇 |
1966年 | 584篇 |
1965年 | 431篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
222.
Zh T A?tbaeva P N Deriabin B V Karal'nik K G Kaverina 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1989,(5):16-20
Highly sensitive and specific erythrocyte diagnostic agents (ED) for the determination of antibodies to Proteus O-antigens have been obtained by the sensitization of formolated sheep red blood cells (SPBC) with activated lipopolysaccharides (LPS) without the use of mediators. The tannin treatment of formolated SRBC and/or the increase of temperature from 45 degrees C to 100 degrees C in the process of the preparation of ED have been found to produce no increase in effectiveness. Antibody ED permitting the detection of Proteus O- and H-antigens has been obtained by the sensitization of formolated chick red blood cells with immunoglobulin preparations to Proteus hydroxylamine antigens, carried out with the use of amidol. The experiments have shown the possibility of using this antibody ED for the determination of O-antibodies in the antigen neutralization test with nonactivated LPS used as an agglutinating agent. The passive hemagglutination test with antibody ED has proved to be a more sensitive method for the detection of O-antibodies than the antigen neutralization test with antigenic ED. The determination of Proteus etiology in the passive hemagglutination test with the use of antigenic ED has been shown to be highly effective in the examination of patients with chronic osteomyelitis at the stage of exacerbation. 相似文献
223.
224.
225.
K Gromysz-Ka?kowska E Szubartowska E Kaczanowska 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1989,92(1):89-93
1. Testosterone reduces the haemolytic action of Ekatin on the morphotic blood elements by accelerating maturation of erythroblastic cells. 2. Testosterone, by accelerating the metabolism of the pesticide causes a defective defence processes of the organism by decreasing the number of macrophages. 3. Intoxication of androgenised birds with Ekatin leads to a breakdown of the systemic adaptive mechanisms by rapid and early switching on the adrenal cortex in response to the stress caused by poisoning. 相似文献
226.
E A Serbinova R A Bakalova Ts S Sto?chev V E Kagan 《Biulleten' eksperimental'no? biologii i meditsiny》1986,102(10):419-421
The efficacy of lipid peroxidation inhibition by the natural antioxidant alpha-tocopherol and 2,2,5,7,8-pentamethyl-6-hydroxy-chromane (PMC), a derivative without hydrocarbon tail, as well as by the synthetic antioxidant 4-methyl-2,6-diterbutyl phenol (BHT) and its phospholipid derivative was studied in the membranes of rat liver microsomes and mitochondria. The presence of hydrocarbon tail in the antioxidant molecule determines the decrease of antioxidant efficiency in biomembranes. PMC and BHT exert a destructive effect on biomembranes, leading to an increase in their permeability to ions. This evidence suggests that the presence of hydrocarbon tail in the molecules of natural antioxidants provides not only for a relatively high antioxidant efficiency but also for a structural stability of biomembranes. 相似文献
227.
228.
Mateusz Lezyk Carsten Jers Louise Kjaerulff Charlotte H. Gotfredsen Maria D. Mikkelsen J?rn D. Mikkelsen 《PloS one》2016,11(1)
This paper describes the discovery of novel α-L-fucosidases and evaluation of their potential to catalyse the transglycosylation reaction leading to production of fucosylated human milk oligosaccharides. Seven novel α-L-fucosidase-encoding genes were identified by functional screening of a soil-derived metagenome library and expressed in E. coli as recombinant 6xHis-tagged proteins. All seven fucosidases belong to glycosyl hydrolase family 29 (GH 29). Six of the seven α-L-fucosidases were substrate-inhibited, moderately thermostable and most hydrolytically active in the pH range 6–7, when tested with para-nitrophenyl-α-L-fucopyranoside (pNP-Fuc) as the substrate. In contrast, one fucosidase (Mfuc6) exhibited a high pH optimum and an unusual sigmoidal kinetics towards pNP-Fuc substrate. When tested for trans-fucosylation activity using pNP-Fuc as donor, most of the enzymes were able to transfer fucose to pNP-Fuc (self-condensation) or to lactose. With the α-L-fucosidase from Thermotoga maritima and the metagenome-derived Mfuc5, different fucosyllactose variants including the principal fucosylated HMO 2’-fucosyllactose were synthesised in yields of up to ~6.4%. Mfuc5 was able to release fucose from xyloglucan and could also use it as a fucosyl-donor for synthesis of fucosyllactose. This is the first study describing the use of glycosyl hydrolases for the synthesis of genuine fucosylated human milk oligosaccharides. 相似文献
229.
W Brandst?dter 《Folia haematologica (Leipzig, Germany : 1928)》1982,109(6):843-848
A report is presented on the results of investigations made in 188 657 prospective blood donors from 1974-1980 within the district of Magdeburg. Methods of investigation and recommendations of the International Society of Blood Transfusion for selecting blood donors are compared. A total of 12337 (= 6.53%) were not admitted as a donor and 1360 blood conserves (0.77%) could not be used for transfusion because of laboratory findings obtained afterwards. Causes are dealt with in detail. The necessity of supervising the health of donors and the existing limitations for it are pointed out. 相似文献
230.