全文获取类型
收费全文 | 30975篇 |
免费 | 16000篇 |
国内免费 | 117篇 |
出版年
2023年 | 54篇 |
2022年 | 183篇 |
2021年 | 571篇 |
2020年 | 2262篇 |
2019年 | 3804篇 |
2018年 | 3940篇 |
2017年 | 4169篇 |
2016年 | 4243篇 |
2015年 | 4307篇 |
2014年 | 3962篇 |
2013年 | 4447篇 |
2012年 | 2233篇 |
2011年 | 1881篇 |
2010年 | 3259篇 |
2009年 | 1975篇 |
2008年 | 984篇 |
2007年 | 504篇 |
2006年 | 504篇 |
2005年 | 519篇 |
2004年 | 477篇 |
2003年 | 431篇 |
2002年 | 432篇 |
2001年 | 359篇 |
2000年 | 310篇 |
1999年 | 244篇 |
1998年 | 72篇 |
1997年 | 56篇 |
1996年 | 45篇 |
1995年 | 44篇 |
1994年 | 54篇 |
1993年 | 47篇 |
1992年 | 79篇 |
1991年 | 66篇 |
1990年 | 45篇 |
1989年 | 57篇 |
1988年 | 52篇 |
1987年 | 41篇 |
1986年 | 43篇 |
1985年 | 31篇 |
1984年 | 51篇 |
1983年 | 27篇 |
1982年 | 27篇 |
1981年 | 22篇 |
1980年 | 16篇 |
1979年 | 28篇 |
1978年 | 28篇 |
1977年 | 21篇 |
1976年 | 13篇 |
1975年 | 16篇 |
1971年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
231.
This paper reviews the systematic status and geographical distribution of 30 odd species of freshwater calanoid copepods in Southeast Asia. Three regions are delineated based on the diversity and abundance of these organisms; Region I being the Southasiatic element, Region II the attenuated belt of copepods and Region III rich in endemic species. The implication of a north-south diminishing of copepod species to inland fisheries is postulated. 相似文献
232.
233.
The freshwater calanoida (crustacea : copepoda) of Singapore and Peninsular Malaysia 总被引:7,自引:7,他引:0
The systematics and geographical distribution of Malaysian and Singapore freshwater calanoid copepods are discussed in details. Neodiaptomus handeli Brehm, N. laii Kiefer, N. blachei (Brehm), N. botulifer Kiefer, N. mephistopheles Brehm, Pseudodiaptomus (Schmackeria) dauglishi Sewell, P. (S.) tollingerae Sewell and Tropodiaptomus spp. Kiefer are all present in the northwestern part of the Peninsula. There are only 4 species, namely, N. handeli, N. botulifer, N. meggitti Kiefer and Tropodiaptomus sp. in the southern half of the Peninsula. The whole of the east coast also has 4 species, i.e. N. handeli, N. malaindosinensis (n.n.), P. (S.) tollingerae and one species of Tropodiaptomus. The only species that cut across a wide range of geographical barriers are N. handeli and Tropodiaptomus. 相似文献
234.
Studies on hemoglobin variants in Korean cattle 总被引:1,自引:0,他引:1
814 hemoglobin samples from Korean cattle were investigated by starch gel electrophoresis for the detection of hemoglobin variants. A new variant of cattle hemoglobin, called Hb, H, was recognized. It has a slower rate of migration than Hb A.
Hemoglobin types from 814 Korean cattle were as follows: 652 of Hb AA type (80.1 %), 133 of Hb AB (16.4 %), 12 of Hb AC (1.5 %), 9 of Hb BB (1.1 %), 2 of Hb BC (0.2 %), 4 of Hb AH (0.5 %), 1 of Hb CH (0.1 %), 1 of Hb HH (0.1 %). These figures correspond to the frequencies: HbA = 0.893, HbB = 0.093, Hbc =0.009, HbH = 0.004.
Gene frequencies at the Hb locus in Korean cattle were compared among six population from different provinces. Generally, high frequencies of HbA were observed in each province. 相似文献
Hemoglobin types from 814 Korean cattle were as follows: 652 of Hb AA type (80.1 %), 133 of Hb AB (16.4 %), 12 of Hb AC (1.5 %), 9 of Hb BB (1.1 %), 2 of Hb BC (0.2 %), 4 of Hb AH (0.5 %), 1 of Hb CH (0.1 %), 1 of Hb HH (0.1 %). These figures correspond to the frequencies: Hb
Gene frequencies at the Hb locus in Korean cattle were compared among six population from different provinces. Generally, high frequencies of Hb
235.
A double-stranded ribonucleic acid (dsRNA) was isolated from coremial extracts of wild type P. claviforme, by methylated-albumin kieselguhr chromatography. Differential centrifugations of the coremial extracts from WT and Sh mutant strains yielded two classes of virus-like particles (VLP), of dimensions 25-30 nm, and 50-70 nm. The possible ecological significance of fungal viruses is discussed. 相似文献
236.
E Mendez C Y Lai A Wodnar-Filipowicz 《Biochemical and biophysical research communications》1975,67(4):1435-1443
The sequence of the four tryptic peptides containing cysteine from cholera toxin has been determined. The cysteine residue in peptide A2, forms a disulfide bridge with the cysteine in the A1 chain located near the NH2-terminus. The region around the latter cysteine residue is characterized by a high content of proline. One of the cysteine residues that form the intrachain disulfide bond in subunit B has been located at position 9 in this subunit. 相似文献
237.
The specificity of the hydrolytic reaction has been compared to that of the synthetic reaction for maltase and isomaltase (alpha-methyl-D-glucosidase) from Saccharomyces oviformis. Maltase which hydrolyzes the alpha-1,4-disaccharide, maltose, and the alpha-1,6-disaccharide, isomaltose, catalyzes the formation of both maltose and isomaltose from free glucose. Isomaltase, which hydrolyzes isomaltose but not maltose, catalyzes the formation only of isomaltose from glucose. Both enzymes hydrolyze p-nitrophenyl-alpha-D-glucoside releasing the alpha-anomer of glucose. The enzymes utilize the alpha-anomer but not the beta-anomer for the synthesis of the disaccharides. These results are consistent with the double displacement mechanism for glycosidases and with the proposal that the glucosyl-enzyme complex is an intermediate in the reaction. The competitive inhibition by D-glucose is independent of its anomeric form for both enzymes. 相似文献
238.
239.
Fabrice Roegiers Joshua Kavaler Nicholas Tolwinski Yu-Ting Chou Hong Duan Fernando Bejarano Diana Zitserman Eric C. Lai 《Genetics》2009,182(1):407-410
Forty years ago, a high frequency of lethal giant larvae (lgl) alleles in wild populations of Drosophila melanogaster was reported. This locus has been intensively studied for its roles in epithelial polarity, asymmetric neural divisions, and restriction of tissue proliferation. Here, we identify a high frequency of lgl alleles in the Bloomington second chromosome deficiency kit and the University of California at Los Angeles Bruinfly FRT40A-lethal P collection. These unrecognized aberrations confound the use of these workhorse collections for phenotypic screening or genetic mapping. In addition, we determined that independent alleles of insensitive, reported to affect asymmetric cell divisions during sensory organ development, carry lgl deletions that are responsible for the observed phenotypes. Taken together, these results encourage the routine testing of second chromosome stocks for second-site alleles of lgl. 相似文献
240.
ZAKβ antagonizes and ameliorates the cardiac hypertrophic and apoptotic effects induced by ZAKα
下载免费PDF全文
![点击此处可从《Cell biochemistry and function》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chien‐Yao Fu Wei‐Wen Kuo Tsung‐Jung Ho Su‐Ying Wen Ling‐Chun Lin Yan‐Shen Tseng Hui‐Chuan Hung Vijaya Padma Viswanadha Chih‐Yang Huang 《Cell biochemistry and function》2016,34(8):606-612
ZAK (sterile alpha motif and leucine zipper containing kinase AZK), a serine/threonine kinase with multiple biochemical functions, has been associated with various cell processes, including cell proliferation, cell differentiation, and cardiac hypertrophy. In our previous reports, we found that the activation of ZAKα signaling was critical for cardiac hypertrophy. In this study, we show that the expression of ZAKα activated apoptosis through both a FAS‐dependent pathway and a mitochondria‐dependent pathway by subsequently inducing caspase‐3. ZAKβ, an isoform of ZAKα, is dramatically expressed during cardiac hypertrophy and apoptosis. The interaction between ZAKα and ZAKβ was demonstrated here using immunoprecipitation. The results show that ZAKβ has the ability to diminish the expression level of ZAKα. These findings reveal an inherent regulatory role of ZAKβ to antagonize ZAKα and to subsequently downregulate the cardiac hypertrophy and apoptosis induced by ZAKα. 相似文献