全文获取类型
收费全文 | 9066篇 |
免费 | 940篇 |
国内免费 | 69篇 |
专业分类
10075篇 |
出版年
2023年 | 62篇 |
2022年 | 106篇 |
2021年 | 218篇 |
2020年 | 148篇 |
2019年 | 196篇 |
2018年 | 211篇 |
2017年 | 213篇 |
2016年 | 283篇 |
2015年 | 464篇 |
2014年 | 462篇 |
2013年 | 594篇 |
2012年 | 719篇 |
2011年 | 639篇 |
2010年 | 459篇 |
2009年 | 400篇 |
2008年 | 511篇 |
2007年 | 451篇 |
2006年 | 410篇 |
2005年 | 360篇 |
2004年 | 385篇 |
2003年 | 307篇 |
2002年 | 295篇 |
2001年 | 158篇 |
2000年 | 112篇 |
1999年 | 120篇 |
1998年 | 78篇 |
1997年 | 79篇 |
1996年 | 67篇 |
1995年 | 60篇 |
1994年 | 55篇 |
1993年 | 56篇 |
1992年 | 81篇 |
1991年 | 76篇 |
1990年 | 86篇 |
1989年 | 83篇 |
1988年 | 71篇 |
1987年 | 60篇 |
1986年 | 54篇 |
1985年 | 72篇 |
1984年 | 53篇 |
1983年 | 49篇 |
1982年 | 52篇 |
1981年 | 42篇 |
1980年 | 51篇 |
1979年 | 50篇 |
1978年 | 33篇 |
1977年 | 35篇 |
1976年 | 39篇 |
1972年 | 31篇 |
1971年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Suzanne Camus Sergio Menéndez Kenneth Fernandes Nelly Kua Geng Liu Dimitris P. Xirodimas David P. Lane Jean-Christophe Bourdon 《Cell cycle (Georgetown, Tex.)》2012,11(8):1646-1655
The discovery that the single p53 gene encodes several different p53 protein isoforms has initiated a flurry of research into the function and regulation of these novel p53 proteins. Full-length p53 protein level is primarily regulated by the E3-ligase Mdm2, which promotes p53 ubiquitination and degradation. Here, we report that all of the novel p53 isoforms are ubiquitinated and degraded to varying degrees in an Mdm2-dependent and -independent manner, and that high-risk human papillomavirus can degrade some but not all of the novel isoforms, demonstrating that full-length p53 and the p53 isoforms are differentially regulated. In addition, we provide the first evidence that Mdm2 promotes the NEDDylation of p53β. Altogether, our data indicates that Mdm2 can distinguish between the p53 isoforms and modify them differently. 相似文献
2.
3.
D. S. Coffman Ben H. Leichtling H. V. Rickenberg 《Journal of cellular biochemistry》1981,15(4):369-385
The phosphoproteins of Dictyostelium discoideum were compared at different stages of development by polyacrylamide gel electrophoresis. Certain phosphoproteins of vegetative amoebae were conserved while others appeared and disappeared during development. Four major phosphoproteins with apparent subunit molecular weights of 50,000, 47,000, 38,000, and 34,000 disappeared precociously in response to exogenous cAMP. Two membranal phosphoproteins, with apparent subunit molecular weights of 80,000 and 81,000, appeared precociously in response to added cAMP. One of these phosphoproteins, molecular weight of 80,000, has been identified tentatively as the “contact site A” glycoprotein. Another membranal protein, with apparent subunit molecular weight of 42,000, unaffected in its appearance by cAMP, has been identified tentatively as phosphoactin. 相似文献
4.
The complete sequence of recombinant human interleukin-2 expressed in Escherichia coli has been confirmed by thermospray liquid chromatography-mass spectrometry (TS-LC-MS) of a tryptic digest derived from 100 micrograms (7 nmol) of reduced carboxymethylated interleukin-2. The preparation was shown by this method to contain predominantly unprocessed N-terminal initiator Met, with some authentic N-terminal Ala; the rest of the protein was as predicted from the DNA sequence, though some deamidated material was noted. TS-LC-MS proved to be a rapid and efficient method for surveying the protein tryptic peptide products allowing all the data to be collected in one chromatographic run; all tryptic fragments were identified by their molecular ions including those for the larger peptides (Mr 1500-3500) which, due to the presence of doubly and triply charged molecular ions, were brought within the mass range of the instrument (1800 Da). It is proposed that TS-LC-MS is a good general method for analyzing recombinant protein digests with respect to sequence confirmation, processing, and post-translational modification, and since each chromatographic peak is identified allows for subsequent monitoring of the protein by LC using uv detection. The method suffers from the disadvantages that all the sample is consumed during the experiment and that no fragment (sequence) ions are generally observed. 相似文献
5.
6.
7.
Xu Liu Ben Chen Lulan Chen Wan-Ting Ren Juan Liu Guoxiang Wang Wei Fan Xin Wang Yun Wang 《PloS one》2013,8(4)
Phenol red is widely used in cell culture as a pH indicator. Recently, it also has been reported to have estrogen-like bioactivity and be capable of promoting cell proliferation in different cell lines. However, the effect of phenol red on primary neuronal culture has never been investigated. By using patch clamp technique, we demonstrated that hippocampal pyramidal neurons cultured in neurobasal medium containing no phenol red had large depolarization-associated epileptiform bursting activities, which were rarely seen in neurons cultured in phenol red-containing medium. Further experiment data indicate that the suppressive effect of the phenol red on the abnormal epileptiform burst neuronal activities was U-shape dose related, with the most effective concentration at 28 µM. In addition, this concentration related inhibitory effect of phenol red on the epileptiform neuronal discharges was mimicked by 17-β-estradiol, an estrogen receptor agonist, and inhibited by ICI-182,780, an estrogen receptor antagonist. Our results suggest that estrogen receptor activation by phenol red in the culture medium prevents formation of abnormal, epileptiform burst activity. These studies highlight the importance of phenol red as estrogen receptor stimulator and cautions of careful use of phenol red in cell culture media. 相似文献
8.
H K Sharma H R Prasanna R S Lane M Rothstein 《Archives of biochemistry and biophysics》1979,194(1):275-282
The rates of synthesis and degradation of enolase and total soluble proteins slow with age in the free-living nematode, Turbatrix aceti. The half-lives are 73 and 58 h for soluble protein and enolase, respectively, in young organisms (5 days old). The respective figures are 163 and 161 h for old organisms (22–30 days old). Similar slowing of protein turnover occurs when the organisms are aged by a repeated screening procedure which avoids the use of fluorodeoxyuridine, an inhibitor of DNA synthesis normally added to aging cultures to obtain synchrony. The results support the idea that slowed protein turnover may be responsible for the formation of altered enzymes in old organisms. 相似文献
9.
10.
H. Ben Slimen F. Suchentrunk A. Memmi H. Sert U. Kryger P.C. Alves A. Ben Ammar Elgaaied 《Journal of Zoological Systematics and Evolutionary Research》2006,44(1):88-99
Systematics and taxonomy of hares of the genus Lepus (Lagomorpha) are under contentious debate, and phylogenetic relationships among many taxa are not well understood. Here we study genetic differentiation and evolutionary relationships among North African hares, currently considered subspecies of Lepus capensis , cape hares ( L. capensis ) from the Cape province in South Africa, and brown hares ( L. europeaus ) from Europe and Anatolia, using maternally (mtDNA) and biparentally (allozymes) inherited markers. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of a c. 1.8 kb long segment of the mitochondrial control region using eight hexanucleotide-recognizing restriction endonucleases yielded 28 haplotypes, and horizontal starch gel electrophoresis of proteins encoded by 25 structural gene loci revealed 52 alleles at 18 polymorphic loci. Diverse phylogenetic analyses (neighbor joining dendrogram, median joining network, multidimensional scaling of pairwise distances, AMOVA, F -statistics, hierarchical F -statistics) of genetic variants revealed marked substructuring of mtDNA into three phylogeographic groups, namely an African, a central European, and an Anatolian, but a somewhat less pronounced overall differentiation of the nuclear genome, despite a relatively high number of population-specific (private) alleles. However, all our results are not incongruent with Petter's (1959: Mammalia 23 , 41; 1961: Z. f. Säugetierkunde 26 , 30; 1972 : Société Des Sciences Naturelles et Physiques du Maroc 52 , 122) hypothesis that North African hares generally belong to L. capensis and that brown hares should be included in this species as well. 相似文献