全文获取类型
收费全文 | 8697篇 |
免费 | 765篇 |
国内免费 | 2篇 |
出版年
2023年 | 46篇 |
2022年 | 56篇 |
2021年 | 172篇 |
2020年 | 140篇 |
2019年 | 149篇 |
2018年 | 265篇 |
2017年 | 248篇 |
2016年 | 350篇 |
2015年 | 449篇 |
2014年 | 471篇 |
2013年 | 721篇 |
2012年 | 745篇 |
2011年 | 811篇 |
2010年 | 559篇 |
2009年 | 440篇 |
2008年 | 492篇 |
2007年 | 452篇 |
2006年 | 443篇 |
2005年 | 369篇 |
2004年 | 383篇 |
2003年 | 349篇 |
2002年 | 333篇 |
2001年 | 71篇 |
2000年 | 60篇 |
1999年 | 65篇 |
1998年 | 74篇 |
1997年 | 58篇 |
1996年 | 55篇 |
1995年 | 66篇 |
1994年 | 36篇 |
1993年 | 59篇 |
1992年 | 57篇 |
1991年 | 34篇 |
1990年 | 39篇 |
1989年 | 24篇 |
1988年 | 17篇 |
1987年 | 18篇 |
1986年 | 21篇 |
1985年 | 26篇 |
1984年 | 32篇 |
1983年 | 10篇 |
1982年 | 17篇 |
1981年 | 17篇 |
1980年 | 16篇 |
1978年 | 18篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1975年 | 12篇 |
1973年 | 14篇 |
1962年 | 9篇 |
排序方式: 共有9464条查询结果,搜索用时 15 毫秒
1.
Maria Teresa Fiorenza Giandomenico Russo Maria Grazia Narducci Antonella Bresin Franco Mangia Arturo Bevilacqua 《Journal of cellular physiology》2020,235(4):3393-3401
Activation of Akt/Protein Kinase B (PKB) by phosphatidylinositol-3-kinase (PI3K) controls several cellular functions largely studied in mammalian cells, including preimplantation embryos. We previously showed that early mouse embryos inherit active Akt from oocytes and that the intracellular localization of this enzyme at the two-cell stage depends on the T-cell leukemia/lymphoma 1 oncogenic protein, Tcl1. We have now investigated whether Akt isoforms, namely Akt1, Akt2 and Akt3, exert a specific role in blastomere proliferation during preimplantation embryo development. We show that, in contrast to other Akt family members, Akt2 enters male and female pronuclei of mouse preimplantation embryos at the late one-cell stage and thereafter maintains a nuclear localization during later embryo cleavage stages. Depleting one-cell embryos of single Akt family members by microinjecting Akt isoform-specific antibodies into wild-type zygotes, we observed that: (a) Akt2 is necessary for normal embryo progression through cleavage stages; and (b) the specific nuclear targeting of Akt2 in two-cell embryos depends on Tcl1. Our results indicate that preimplantation mouse embryos have a peculiar regulation of blastomere proliferation based on the activity of the Akt/PKB family member Akt2, which is mediated by the oncogenic protein Tcl1. Both Akt2 and Tcl1 are essential for early blastomere proliferation and embryo development. 相似文献
2.
Dominique Dorin-Semblat Claudia Demarta-Gatsi Romain Hamelin Florence Armand Teresa Gil Carvalho Marc Moniatte Christian Doerig 《PloS one》2015,10(12)
Casein kinase 1 (CK1) is a pleiotropic protein kinase implicated in several fundamental processes of eukaryotic cell biology. Plasmodium falciparum encodes a single CK1 isoform, PfCK1, that is expressed at all stages of the parasite’s life cycle. We have previously shown that the pfck1 gene cannot be disrupted, but that the locus can be modified if no loss-of-function is incurred, suggesting an important role for this kinase in intra-erythrocytic asexual proliferation. Here, we report on the use of parasite lines expressing GFP- or His-tagged PfCK1 from the endogenous locus to investigate (i) the dynamics of PfCK1 localisation during the asexual cycle in red blood cells, and (ii) potential interactors of PfCK1, so as to gain insight into the involvement of the enzyme in specific cellular processes. Immunofluorescence analysis reveals a dynamic localisation of PfCK1, with evidence for a pool of the enzyme being directed to the membrane of the host erythrocyte in the early stages of infection, followed by a predominantly intra-parasite localisation in trophozoites and schizonts and association with micronemes in merozoites. Furthermore, we present strong evidence that a pool of enzymatically active PfCK1 is secreted into the culture supernatant, demonstrating that PfCK1 is an ectokinase. Our interactome experiments and ensuing kinase assays using recombinant PfCK1 to phosphorylate putative interactors in vitro suggest an involvement of PfCK1 in many cellular processes such as mRNA splicing, protein trafficking, ribosomal, and host cell invasion. 相似文献
3.
Iwanowska Anna; Tykarska Teresa; Kuras Mieczyslaw; Zobel Alicja M. 《Annals of botany》1994,74(4):313-320
During embryogenesis and maturation of an embryo the tissuescovering it produce phenolic compounds the localization of whichchanges during maturation of the embryo. In the ovary containinga globular embryo, phenolics are located in the epidermis ofthe integumentum externum and the innermost layer of the integumentuminternum. In the ovule at the stage at which heart- and torpedo-shapedembryos are present, phenolic compounds are visible in the stellarcells, the innermost cells of the integumentum internum andthe endosperm. In hard, green seeds, after the integumentuminternum and layers over the stellar cells gradually disappear,the remaining tissue contains cell walls impregnated with phenolics.Mature, black seeds contain only one distinct layer of cellsstellarcells, which, like the other compressed cell walls, are impregnatedwith phenolics. In this way they constitute a barrier betweenthe embryo and its environment.Copyright 1994, 1999 AcademicPress Brassica napus, seed coat, integumentum, phenolic compounds 相似文献
4.
5.
Vertical plankton transport due to self-induced convection 总被引:2,自引:0,他引:2
The slightly increased density of Chlorella over that of purewater is shown to be capable of driving convective water motionswhich lead to very efficient vertical transport. 相似文献
6.
7.
8.
9.
Perera-Castro Alicia Victoria Flexas Jaume González-Rodríguez Águeda María Fernández-Marín Beatriz 《Photosynthesis research》2021,149(1-2):135-153
Photosynthesis Research - In Antarctica, multiple stresses (low temperatures, drought and excessive irradiance) hamper photosynthesis even in summer. We hypothesize that controlled inactivation of... 相似文献
10.
The vegetables germplasm conservation programme in Poland was started in 1982, activities under this program resulted up to
this date in building up a tomato germplasm collection of 782 accessions that are available for distribution to breeders and
researchers in Poland and abroad. Between 1990 and 1999 we distributed 651 tomato seed samples to breeders and scientists
in Poland, and 95 samples to users abroad. During 1990 – 1999 the 652 tomato accessions were evaluated for 43 traits of plants
and fruits. Work is in progress to expand the collection and identify useful characteristics of the collected material, and
to make use of them in breeding and other research works. 相似文献