全文获取类型
收费全文 | 343881篇 |
免费 | 28632篇 |
国内免费 | 268篇 |
出版年
2021年 | 3286篇 |
2019年 | 2949篇 |
2018年 | 5124篇 |
2017年 | 4846篇 |
2016年 | 6466篇 |
2015年 | 7655篇 |
2014年 | 8870篇 |
2013年 | 12105篇 |
2012年 | 13627篇 |
2011年 | 13700篇 |
2010年 | 9309篇 |
2009年 | 8029篇 |
2008年 | 11620篇 |
2007年 | 11611篇 |
2006年 | 11125篇 |
2005年 | 10134篇 |
2004年 | 10048篇 |
2003年 | 9479篇 |
2002年 | 9089篇 |
2001年 | 14459篇 |
2000年 | 14237篇 |
1999年 | 11010篇 |
1998年 | 3632篇 |
1997年 | 3449篇 |
1996年 | 3428篇 |
1995年 | 3143篇 |
1994年 | 3043篇 |
1992年 | 8327篇 |
1991年 | 8043篇 |
1990年 | 8065篇 |
1989年 | 7925篇 |
1988年 | 7240篇 |
1987年 | 6920篇 |
1986年 | 6194篇 |
1985年 | 6551篇 |
1984年 | 5199篇 |
1983年 | 4508篇 |
1982年 | 3228篇 |
1981年 | 2976篇 |
1979年 | 4851篇 |
1978年 | 3679篇 |
1977年 | 3443篇 |
1976年 | 3319篇 |
1975年 | 3907篇 |
1974年 | 4202篇 |
1973年 | 4188篇 |
1972年 | 3672篇 |
1971年 | 3382篇 |
1970年 | 3112篇 |
1969年 | 2954篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
U A Bommer G Lutsch J Behlke J Stahl N Nesytova A Henske H Bielka 《European journal of biochemistry》1988,172(3):653-662
The location of initiation factor eIF-2 and of its subunits in quaternary initiation complexes (40S-ribosomal-subunit.eIF-2. GuoPP[CH2]P.Met-tRNAf) was investigated by immunoelectron microscopy. Quaternary complexes were fixed with glutaraldehyde and reacted with affinity-purified polyclonal antibodies against eIF-2 alpha, eIF-2 beta or eIF-2 gamma. The dimeric immune complexes obtained by sucrose gradient centrifugation were investigated electron microscopically after negative staining. Antibody-binding sites were observed on the interface side of the 40S ribosomal subunit in the region between the 'head' and the 'body' (neck region) of the 40S ribosomal subunit. Within this region, eIF-2 alpha points to the rear side, whereas eIF-2 beta and eIF-2 gamma point to the frontal side of the 40S subunit indicating an elongated shape of eIF-2 about 15 nm long. By analytical ultracentrifugation of isolated eIF-2 the sedimentation and diffusion coefficients were determined to be 6.54 S and 4.74 x 10(-7) cm2/s respectively. From these data, a molar mass of 122.4 kg/mol and a dry volume of 147.4 nm3 were calculated. For the shape of eIF-2 a prolate ellipsoid of revolution is assumed with a maximal length of about 15 nm and with an axial ratio of about 1:3.5. This conclusion is further confirmed by a calculated frictional ratio of 1.37 and a Stokes radius of about 4.54 nm. 相似文献
992.
S N Khil'ko M A Kirasova V R Isakova M P Burgasova E K Kiseleva 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1989,(7):41-47
An enzyme-linked immunosorbent assay (ELISA) was developed for analysis of rabbit and mouse IgG antibodies specific to adenoviral hexon. The anti-hexon antibodies were detected by capture with purified hexon coated onto polystyrene microtiter plates and visualizing them by respective anti-IgG horseradish peroxidase conjugates. In the sera from hyperimmunized rabbits and mice as well as in the mouse ascite fluids the ELISA procedure revealed primarily type-specific (epsilon) and genus-specific (alpha) antigenic determinants in hexon but not those of intermediate specificities. 相似文献
993.
994.
M. Konečná 《Zeitschrift fur angewandte Ichthyologie》2012,28(5):806-810
This study focuses on assessing the reproduction mode of an important model species for evolutionary and behavioural ecology by using digital image analysis: the European bitterling Rhodeus amarus (Bloch, 1782). Specifications of mode of reproduction were determined using oocyte size distribution, seasonal dynamics in mean oocyte diameter and total number of oocytes in ovary samples gained from April to July 2007. The rapid oocyte count was enabled by using lucia image analysis software, which also provided measurement and colour estimations of oocytes. Bitterling ovaries showed features typical for indeterminate spawners, i.e. a continuous distribution of oocyte size over the reproductive season and recruitment of new pre‐vitelogenic oocytes in the second half of the reproductive season. These results are consistent with the view that the European bitterling is a batch spawning fish with indeterminate fecundity. 相似文献
995.
Patients with primary polycythaemia may present clinical features which lead to an erroneous diagnosis of intracerebral neoplasm. Three such cases are described in detail in this report. 相似文献
996.
997.
B P Sokolov V V Dzhemelinski? V N Kalinin 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1989,(6):45-46
The simple technique for isolation of high-molecular eucaryotic DNA has been proposed. It includes cell or nuclei lysates by sodium dodecylsulfate in the presence of pronase, proteins precipitation by potassium acetate, DNA precipitation by ethanol. The DNA isolated by this technique is easily cleaved by restriction endonucleases and can be used for analysis of the unique genes by blot-hybridization. The yield of DNA is similar or somewhat higher than that in case of using the standard methods including phenol extraction or phenol-chloroform extraction. 相似文献
998.
999.
A B Maslennikov S P Kovalenko E A Oteva T A Filimonova N P Mertvetsov 《Genetika》1991,27(12):2152-2156
Restriction fragments' length polymorphism in the region of apolipoprotein A-I (apo A-I) gene was investigated in Novosibirsk (Siberia, USSR) population. Correlation between PstI apo A-I alleles (2,2 kb-P1; 3,3 kb-P2) and total cholesterol, triglycerides, high density polyproteins cholesterol, and apolipoprotein A-I level was analysed. A tendency to increase in cholesterol index of atherogenicity and to decrease in high density lipoproteins cholesterol as well as apolipoprotein A-I level was shown to occur for P1P2 genotype patients. 相似文献
1000.
Sixteen raptors, including one eagle, two falcons, five hawks and eight owls, were found to have developmental ocular lesions. The most common lesion was microphthalmia. Other findings included cataract, microphakia, retinal dysplasia, malformation of the ciliary body, choroid and pecten, and lentoid formation. Specific causes for these lesions could not be determined. It is hypothesized that developmental ocular disease probably is more common than available reports indicate. 相似文献