全文获取类型
收费全文 | 6443篇 |
免费 | 430篇 |
国内免费 | 1篇 |
出版年
2023年 | 62篇 |
2022年 | 85篇 |
2021年 | 168篇 |
2020年 | 140篇 |
2019年 | 146篇 |
2018年 | 183篇 |
2017年 | 184篇 |
2016年 | 241篇 |
2015年 | 363篇 |
2014年 | 359篇 |
2013年 | 481篇 |
2012年 | 561篇 |
2011年 | 553篇 |
2010年 | 346篇 |
2009年 | 279篇 |
2008年 | 376篇 |
2007年 | 353篇 |
2006年 | 297篇 |
2005年 | 283篇 |
2004年 | 277篇 |
2003年 | 215篇 |
2002年 | 212篇 |
2001年 | 52篇 |
2000年 | 39篇 |
1999年 | 39篇 |
1998年 | 73篇 |
1997年 | 48篇 |
1996年 | 33篇 |
1995年 | 30篇 |
1994年 | 30篇 |
1993年 | 30篇 |
1992年 | 23篇 |
1991年 | 15篇 |
1990年 | 24篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 21篇 |
1986年 | 19篇 |
1985年 | 31篇 |
1984年 | 21篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1981年 | 12篇 |
1980年 | 16篇 |
1979年 | 9篇 |
1977年 | 7篇 |
1973年 | 9篇 |
1972年 | 7篇 |
1968年 | 11篇 |
1961年 | 5篇 |
排序方式: 共有6874条查询结果,搜索用时 31 毫秒
991.
992.
Genetic signature of the northward expansion of the Egyptian mongoose Herpestes ichneumon (Herpestidae) in the Iberian Peninsula
下载免费PDF全文
![点击此处可从《Biological journal of the Linnean Society. Linnean Society of London》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tânia Barros Eduardo Ferreira Rita Gomes Rocha Philippe Gaubert Victor Bandeira Luis Souto António Mira Carlos Fonseca 《Biological journal of the Linnean Society. Linnean Society of London》2016,118(3):686-697
In the last three decades, the range of the Egyptian mongoose (Herpestes ichneumon) has increased in the Iberian Peninsula. A panel of microsatellites was used to confront the patterns of genetic diversity of the species with the scenario of its recent northward expansion in its Iberian range. Evidence of substructure and significant genetic differentiation within the studied population were recorded, with a central‐northern subpopulation (CNorth) and a southern subpopulation (S). Northward range expansion was supported by the observed allelic frequencies, diversity parameters, and observed heterozygosity of the studied loci, with S showing a higher allelic diversity and a higher number of private alleles than CNorth. Patterns of isolation‐by‐distance and isolation‐by‐barrier as a result of the Tagus River were demonstrated, suggesting that the river acted as a semi‐permeable barrier, possibly leading to genetic differentiation of the studied population. The observed individuals from CNorth in southern locations and individuals from S in central/northern areas might comprise evidence for long‐range dispersals across the studied range. A bottleneck event after population expansion was supported by a significant heterozygosity deficiency in CNorth, which is in agreement with a scenario of founder events occurring in recently colonized areas after the crossing of the Tagus River. 相似文献
993.
994.
Luiz Fernando Freire Royes Patrícia Gabbi Leandro Rodrigo Ribeiro Iuri Domingues Della-Pace Fernanda Silva Rodrigues Ana Paula de Oliveira Ferreira Mauro Eduardo Porto da Silveira Junior Luís Roberto Hart da Silva Alan Barroso Araújo Grisólia Danielle Valente Braga Fernando Dobrachinski Anderson Manoel Herculano Oliveira da Silva Félix Alexandre Antunes Soares Sara Marchesan Ana Flavia Furian Mauro Schneider Oliveira Michele Rechia Fighera 《Amino acids》2016,48(6):1373-1389
995.
996.
997.
Moltó E Bonzón-Kulichenko E Gallardo N Andrés A 《Archives of biochemistry and biophysics》2007,467(1):31-40
Metallothioneins are cysteine-rich proteins, with a high capacity to bind metallic ions, and for which a precise biological role has not been established. Here we investigated the effects of MTPA, a metallothionein from the lobster Panulirus argus, on mitochondrial oxygen consumption and ROS production. An HPLC-RP-ESI-MS analysis of recombinant MTPA showed that despite its extra Cys, MTPA binds 6 Zn2+ per molecule akin to other crustacean metallothioneins with 18 Cys. The extra Cys is not involved in zinc binding, since its side-chain would be oriented to the outside of the molecule according to a preliminary model of the tridimensional structure of MTPA. MTPA-Zn2+6 is imported into the hepatopancreatic mitochondria intermembrane space and inhibits mitochondrial oxygen consumption, increasing thereby ROS production. Nevertheless, the stimulation of ROS production by MT-bound Zn2+ is weaker compared to equivalent amounts of free Zn2+, suggesting that MTPA protects against oxidative stress. This constitutes the first report on metallothioneins effects on mitochondrial function in invertebrates and agrees with the results described for mammals, suggesting a connection between metallothioneins and energy metabolism. 相似文献
998.
The aim of the present study was to examine the effects of experimental cryptorchidism on rat testicular phospholipids and neutral lipids that contain long-chain (C(18)-C(22)) and very long-chain (VLC) (C(24)-C(32)) polyunsaturated fatty acids (PUFA). The weight of the cryptorchid testis was nearly half that of the contralateral control at postsurgical Days 7-10 owing to the depletion of germ cells. Concomitantly, the amounts of major glycerophospholipids (GPL) and sphingomyelin (SM) per testis decreased. Both these lipids lost their characteristic long-chain and very long-chain PUFA, notably 22:5n-6 and 28:4n-6, respectively, which suggests that these species are linked to the membranes of germ cells. In contrast, the amounts and concentrations of triglycerides (TG; triacylglycerols and 1-O-alkyl-2,3-diacylglycerols) and cholesterol esters (CE) increased several fold in the surviving cells (mainly Sertoli cells) in the cryptorchid testis. All these neutral lipids, but especially CE, accumulated large amounts of the major PUFA of the testis, 22:5n-6, as well as pentaenes with longer carbon chains (i.e., 24:5n-6 in TG and 28:5n-6 in CE). This accretion suggests that neutral lipids may store preformed PUFA coming from dying germ cell GPL and also VLCPUFA no longer needed as a source of PUFA destined to assemble new germ cell GPL. The lipid adjustments observed in cryptorchidism suggest a possible role for Sertoli cell CE in the turnover and conservation of PUFA within seminiferous tubules. 相似文献
999.
Unfolding kinetics of beta-lactoglobulin induced by surfactant and denaturant: a stopped-flow/fluorescence study
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The beta-->alpha transition of beta-lactoglobulin, a globular protein abundant in the milk of several mammals, is investigated in this work. This transition, induced by the cationic surfactant dodecyltrimethylammonium chloride (DTAC), is accompanied by partial unfolding of the protein. In this work, unfolding of bovine beta-lactoglobulin in DTAC is compared with its unfolding induced by the chemical denaturant guanidine hydrochloride (GnHCl). The final protein states attained in the two media have quite different secondary structure: in DTAC the alpha-helical content increases, leading to the so-called alpha-state; in GnHCl the amount of ordered secondary-structure decreases, resulting in a random coil-rich final state (denatured, or D, state). To obtain information on both mechanistic routes, in DTAC and GnHCl, and to characterize intermediates, the kinetics of unfolding were investigated in the two media. Equilibrium and kinetic data show the partial accumulation of an on-pathway intermediate in each unfolding route: in DTAC, an intermediate (I(1)) with mostly native secondary structure but loose tertiary structure appears between the native (beta) and alpha-states; in GnHCl, another intermediate (I(2)) appears between states beta and D. Kinetic rate constants follow a linear Chevron-plot representation in GnHCl, but show a more complex mechanism in DTAC, which acts like a stronger binding species. 相似文献
1000.