全文获取类型
收费全文 | 19810篇 |
免费 | 1542篇 |
国内免费 | 6篇 |
出版年
2023年 | 183篇 |
2022年 | 147篇 |
2021年 | 321篇 |
2020年 | 269篇 |
2019年 | 286篇 |
2018年 | 715篇 |
2017年 | 608篇 |
2016年 | 730篇 |
2015年 | 672篇 |
2014年 | 769篇 |
2013年 | 1200篇 |
2012年 | 1615篇 |
2011年 | 1731篇 |
2010年 | 941篇 |
2009年 | 683篇 |
2008年 | 1247篇 |
2007年 | 1126篇 |
2006年 | 1066篇 |
2005年 | 878篇 |
2004年 | 872篇 |
2003年 | 819篇 |
2002年 | 704篇 |
2001年 | 491篇 |
2000年 | 616篇 |
1999年 | 363篇 |
1998年 | 218篇 |
1997年 | 148篇 |
1996年 | 141篇 |
1995年 | 113篇 |
1994年 | 112篇 |
1993年 | 117篇 |
1992年 | 150篇 |
1991年 | 118篇 |
1990年 | 84篇 |
1989年 | 75篇 |
1988年 | 71篇 |
1987年 | 67篇 |
1986年 | 44篇 |
1985年 | 79篇 |
1984年 | 60篇 |
1983年 | 56篇 |
1982年 | 55篇 |
1981年 | 43篇 |
1980年 | 43篇 |
1979年 | 48篇 |
1978年 | 41篇 |
1977年 | 53篇 |
1976年 | 44篇 |
1975年 | 34篇 |
1973年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 671 毫秒
91.
Alicia Mimbrera Luis Rivas Faustino Mollinedo Emilio Muñoz Vicente Larraga 《Molecular and cellular biochemistry》1983,56(1):73-80
Summary The combined use of proteolytic digestion and lactoperoxidase catalyzed labelling with [125I] applied to membrane-bound or soluble pure F1-ATPase from Micrococcus lysodeikticus has allowed us to establish the topography of its , , and subunits within the protein molecule and with respect to the plane of the membrane.The subunit is most externally located to the membrane bilayer looking towards the cytoplasmic face, a position consistent with its proposed catalytic role. The and subunits lie in an intermediate layer between the subunits and the membrane, in which the subunit occupies a central position within the F1-ATPase molecule in contact with the subunit. The subunit appears to be tightly bound to the F0 component of the ATPase complex, probably buried in the membrane bilayer. A molecular arrangement of M. lysodeikticus ATPase is proposed that, taking into account the subunit stoichiometry 3 3 2 2 (MW 420 000), accommodates the role assigned to each subunit and most, if not all, the known properties of this bacterial energy-transducing protein. 相似文献
92.
The time of the last DNA replication of the Mauthner's neuron precursor cell has been investigated using radioautography. Embryos of Xenopus laevis were labeled at different stages of early development by single microinjections of tritiated thymidine. Labeling times were designed to cover the entire period of development between gastrula and hatching stages. The embryos were fixed at later stages (41 to 44, according to Nieuwkoop and Faber, 1967), when the Mauthner neuron can be readily distinguished by its characteristically large size and large nucleolus.Mauthner neurons of embryos which received tritiated thymidine from stage 10 (beginning of gastrulation) to stage 12 (advanced gastrula, medium yolk plug) were always labeled. Those embryos which received the isotope at or after stage (advanced gastrula, small yolk plug) were never found labeled. These results imply that the last DNA replication of the cell destined to give rise to the Mauthner neuron occurs during the last gastrula stages. This last DNA replication immediately proceeds the time of the so-called “histogenetic determination” of the Mauthner neuron proposed to correspond to stage 13 (slit blastopore) by Stefanelli (1951).Therefore it appears that the developmental program of the Mauthner neuron involves a remarkably early cessation of DNA replication closely followed by histogenetic determination. This is the earliest known event of this type for a specific, well characterized neuron in the amphibian embryo. 相似文献
93.
94.
95.
Regression analysis of the spontaneous spike activity of neurons in Helix pomatia was carried out with the aim to establish the statistical parameters of this activity under constant experimental conditions and during longer time intervals. The activity of 38 randomly chosen neurons in visceral and parietal ganglia, penetrated by microelectrodes and activated either endogenously by pacemaker potentials or by synaptic inputs, was recorded during time intervals lasting from 20 min to 3 h. The main results of the statistical analyses are presented in the table where the parameters of both cell types are listed. The validity of the regression analysis applied here is discussed from the point of the possibility it offers for carrying on the data processing quickly and without applying complex calculating means. The results are also considered regarding the current interest of our research group. 相似文献
96.
97.
J. Řičica 《Folia microbiologica》1969,14(4):322-326
A proposal for a graphical solution of the design of a multi-stage continuous culture system is presented. The holding times
in individual stages are derived from the reciprocal values of the growth rate and of the product formation rate and plotted
against the cell and product concentrations. Characteristic changes of physiologically significant paramaters are then projected
on these production curves.
Dedicated to Academican Ivan Málek on the occasion of his 60th birthday 相似文献
98.
Resumen Se presentan 15 casos de aspergilosis recolectados en diferentes ciudades del país. Doce fueron casos autopsiados. Los tres restantes se refieren a pacientes en quienes se efectuó una lobectomía pulmonar superior derecha por aspergiloma gigante intracavitario. En los doce primeros existía una enfermedad básica que había alterado seriamente el estado general del paciente; once de ellos habían recibido antibióticos, cinco habían recibido esteroides, y dos, agentes citotóxicos. Se cree que, tanto el estado general del paciente, como la administración de dichas drogas, favorecieron la infección micótica. De los tres casos con aspergiloma intracavitario gigante, se cree que, en uno, la micosis se implantó en una caverna tuberculosa cicatrizada. En los otros dos, la cavidad era un bronquio localmente dilatado y se consideró que no existía una infección tuberculosa.ElAspergillus posee un amplio espectro de patogenicidad. Se le puede observar en lesiones que van desde una localización intrabronquial, acompañada de mínima o nula reacción inflamatoria, hasta casos en los cuales existen lesiones pulmonares necrotizantes con diseminación hematógena a otros órganos (sistema nervioso central, hígado, riñón). 相似文献
99.
100.
A?koliv na zá kladě mnoha pokus? se p? edpokládalo, ?e tzv. bÍlkovinná v?etena v buňkách tzn. buně?né inkluse X-viru kaktus? (Ca XV), jsou slo?ena z ?etních prodlou?ených ?ásti Ca XV, p?esto to dosud nebylo proká zá no. Proto jsme se pokusili pomocÍ fluoreskujÍcÍch protilátek doká ?at, ?e bilkovinná v?etena jsou skute?ně agregáty virových ?ástic. V těto práci jsme pouzili tzv. nep?Ímé metody. Nejprve jsme p? sobili na buňky obsahujÍci tato v?etena homologiokým antisé rem proti Ca XV, zÍskanym imunizacÍ králÍk? a teprve potom jsme buňky vlo?ili do roztoku fluoreskujicÍch protilátek proti králicimu γglobulinu. BÍlkovinná v?etena svitila potom ve fluorescen?nÍm mikroskopu silně ?lutozeleně (bylopou?ito fluoresceinisothiocyaná tu). Tato fluorescence ná m uká zala, ?e nastala pozitivnÍ reakce a ?e bÍlkovianá v?etena jsou slo?ena z virových ?ástic. ?etné kontrolnÍ pokusy potvrdily ná? základnÍ pokus. 相似文献