全文获取类型
收费全文 | 94713篇 |
免费 | 5866篇 |
国内免费 | 18篇 |
出版年
2021年 | 1175篇 |
2020年 | 1003篇 |
2019年 | 1003篇 |
2018年 | 2495篇 |
2017年 | 2195篇 |
2016年 | 2998篇 |
2015年 | 3984篇 |
2014年 | 4116篇 |
2013年 | 5480篇 |
2012年 | 6498篇 |
2011年 | 5794篇 |
2010年 | 3729篇 |
2009年 | 2782篇 |
2008年 | 4467篇 |
2007年 | 4188篇 |
2006年 | 4157篇 |
2005年 | 3506篇 |
2004年 | 3531篇 |
2003年 | 3135篇 |
2002年 | 2912篇 |
2001年 | 2291篇 |
2000年 | 2136篇 |
1999年 | 1679篇 |
1998年 | 791篇 |
1997年 | 547篇 |
1996年 | 627篇 |
1995年 | 594篇 |
1994年 | 541篇 |
1992年 | 1101篇 |
1991年 | 999篇 |
1990年 | 989篇 |
1989年 | 1022篇 |
1988年 | 879篇 |
1987年 | 892篇 |
1986年 | 805篇 |
1985年 | 900篇 |
1984年 | 746篇 |
1983年 | 660篇 |
1982年 | 567篇 |
1979年 | 801篇 |
1978年 | 620篇 |
1977年 | 595篇 |
1975年 | 671篇 |
1974年 | 693篇 |
1973年 | 671篇 |
1972年 | 616篇 |
1971年 | 549篇 |
1970年 | 586篇 |
1969年 | 653篇 |
1968年 | 628篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
R J Srám 《Molecular & general genetics : MGG》1970,106(3):286-288
Summary Ethylenimine, ethyl methanesulfonate and formaldehyde have been shown to produce a storage effect in dominant lethality in Drosophila melanogaster. 相似文献
22.
J. Vlasák 《Biologia Plantarum》1981,23(6):406-413
Cell nuclei have been released from various plant tissues (barley leaves, roots and embryos, tobacco leaves and tissue cultures,Vicia faba roots,Arabidopsis thaliana leaves) by several homogenization methods and the optimal method was established for each tissue. The effect of the composition
of isolation medium on the yield and appearance of isolated nuclei was also studied. Longer incubation withn-octanol increases the yield considerably in most cases. Low concentrations of osmoticum increase the yield and their adverse
effect on the integrity of nuclei is of little significance. Gum arabic has a favourable effect on nuclei isolation from roots
only. 相似文献
23.
Carmen de Sena-Tomás Mónica Navarro-González Ursula Kües José Pérez-Martín 《Genetics》2013,195(1):47-57
The fungal fruiting body or mushroom is a multicellular structure essential for sexual reproduction. It is composed of dikaryotic cells that contain one haploid nucleus from each mating partner sharing the same cytoplasm without undergoing nuclear fusion. In the mushroom, the pileus bears the hymenium, a layer of cells that includes the specialized basidia in which nuclear fusion, meiosis, and sporulation occur. Coprinopsis cinerea is a well-known model fungus used to study developmental processes associated with the formation of the fruiting body. Here we describe that knocking down the expression of Atr1 and Chk1, two kinases shown to be involved in the response to DNA damage in a number of eukaryotic organisms, dramatically impairs the ability to develop fruiting bodies in C. cinerea, as well as other developmental decisions such as sclerotia formation. These developmental defects correlated with the impairment in silenced strains to sustain an appropriated dikaryotic cell cycle. Dikaryotic cells in which chk1 or atr1 genes were silenced displayed a higher level of asynchronous mitosis and as a consequence aberrant cells carrying an unbalanced dose of nuclei. Since fruiting body initiation is dependent on the balanced mating-type regulator doses present in the dikaryon, we believe that the observed developmental defects were a consequence of the impaired cell cycle in the dikaryon. Our results suggest a connection between the DNA damage response cascade, cell cycle regulation, and developmental processes in this fungus. 相似文献
24.
25.
Condon Tom Hakim Abbas Moran Antonio B. Zenteno Blumstein Daniel T. 《Journal of Ethology》2021,39(1):89-96
Journal of Ethology - Animals emit predator-elicited calls in response to potential predation threats. These vocalizations induce a variety of anti-predator behaviors in conspecific receivers... 相似文献
26.
27.
V jarovisovaných a nejarovisovaných obilkách jedné ozimé a jedné jarní odr?dy p?enice byly chromatograficky stanoveny látky typu auxin? a giberelin?. Chromatogramy byly vyhodnoceny pomocí biologických test?. U ozimé odr?dy jsme nena?li rozdíly v rozlo?ení r?stových látek mezi jarovisovanou a nejarovisovanou variantou. U jarní odr?dy jsme rozdíly na?li. Na základě výsledk? soudíme, ?e rozdíly mezi oběma variantami jarní odr?dy byly zp?sobeny nespecifickým p?sobením nízké teploty a ?e proces jarovisace není kausálně spjat se změnami hladiny r?stových látek. 相似文献
28.
Klein , Richard M. (New York Bot. Gdn., New York, N.Y.), and Deana T. Klein. Interaction of ionizing and visible radiation in mutation induction in Neurospora crassa. Amer. Jour. Bot. 49(8): 870–874. 1962.—Conidia of the purple adenineless strain of N. crassa were irradiated with 25 kr of X rays and then exposed to far-red or red radiations or to far-red followed by red radiation. Far-red light, without effect on un-irradiated conidia, augmented the genetic damage caused by X rays as measured by survival (colony count), back mutation to adenine prototrophy, and the induction of mutants affecting colony morphology. Post-X-irradiation with red light ameliorated the severity of X-radiation as measured by survival and back mutation. The potentiation of X-ray-induced genetic damage by far-red light could be completely negated by subsequent exposure to red light. 相似文献
29.
30.
Dr. Ed. Formánek 《Plant Systematics and Evolution》1888,38(12):419-423
Ohne Zusammenfassung 相似文献