全文获取类型
收费全文 | 1721篇 |
免费 | 190篇 |
出版年
2023年 | 8篇 |
2022年 | 29篇 |
2021年 | 47篇 |
2020年 | 13篇 |
2019年 | 26篇 |
2018年 | 36篇 |
2017年 | 20篇 |
2016年 | 51篇 |
2015年 | 80篇 |
2014年 | 70篇 |
2013年 | 89篇 |
2012年 | 117篇 |
2011年 | 103篇 |
2010年 | 76篇 |
2009年 | 68篇 |
2008年 | 100篇 |
2007年 | 95篇 |
2006年 | 93篇 |
2005年 | 74篇 |
2004年 | 82篇 |
2003年 | 78篇 |
2002年 | 76篇 |
2001年 | 20篇 |
2000年 | 18篇 |
1999年 | 26篇 |
1998年 | 23篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 17篇 |
1992年 | 11篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 11篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1973年 | 8篇 |
1972年 | 10篇 |
1970年 | 10篇 |
排序方式: 共有1911条查询结果,搜索用时 14 毫秒
91.
92.
Length–weight relationship of thirteen demersal fishes from the tropical Brazilian continental shelf
Leandro N. Eduardo Thierry Frdou Alex S. Lira Lucas V. S. Silva Beatrice P. Ferreira Arnaud Bertrand Frdric Mnard Flvia Lucena-Frdou 《Zeitschrift fur angewandte Ichthyologie》2019,35(2):590-593
This study provides the length‐weight relationship (LWR) for 13 demersal fish species belonging to 11 families and 8 orders. Data were collected in the northeast Brazilian continental shelf during two scientific surveys (2015 and 2017) using a bottom trawl net (side length of body mesh: 40 mm, side length of cod‐end mesh: 25 mm) at 35 stations between 15 and 60 m of depth. We provide novel LWRs for four species and expand the size range of 9 relationships previously established. 相似文献
93.
Rosangela Marchelli Roberto Corradini Terenzio Bertuzzi Gianni Galaverna Arnaldo Dossena Francesco Gasparrini Beatrice Galli Claudio Villani Domenico Misiti 《Chirality》1996,8(6):452-461
The copper(II) complexes of two new diastereomeric ligands, N2-(R)- and N2-(S)-2′-hydroxypropyl-(S)-phenylalaninamide [(R, S)-1 and (S, S)-1], have been used as additives to the eluent in high-performance liquid chromatography (HPLC) reversed phase for the chiral separation of DNS-amino acids. The aim was that of comparing the separation process obtained by the chiral eluent with that obtained by an analogous bonded stationary phase containing (S)-phenylalaninamide, previously studied [CSP-(S)-Phe-NH2]. The affinity of the ternary complexes for the C18 column was determined by adsorption experiments in HPLC. It was shown that the two systems (chiral eluent, chiral stationary phase) work according to different mechanisms. Ternary complex formation in solution was studied by fluorescence spectroscopy. It was shown that chiral separation with the Cu(II) complexes added to the eluent was determined by the relative affinities of the ternary complexes for the column-stationary phase rather than by their stabilities in solution. With CSP-(S)-Phe-NH2 the separation is accounted for by the relative stabilities of the ternary complexes, which depends mainly on the “allowed” geometry of the complex and on the steric repulsion of the amino acid side chain with the spacer. © 1996 Wiley-Liss, Inc. 相似文献
94.
95.
Mitochondrial Group II Introns, Cytochrome c Oxidase, and Senescence in Podospora anserina 下载免费PDF全文
Odile Begel Jocelyne Boulay Beatrice Albert Eric Dufour Annie Sainsard-Chanet 《Molecular and cellular biology》1999,19(6):4093-4100
Podospora anserina is a filamentous fungus with a limited life span. It expresses a degenerative syndrome called senescence, which is always associated with the accumulation of circular molecules (senDNAs) containing specific regions of the mitochondrial chromosome. A mobile group II intron (alpha) has been thought to play a prominent role in this syndrome. Intron alpha is the first intron of the cytochrome c oxidase subunit I gene (COX1). Mitochondrial mutants that escape the senescence process are missing this intron, as well as the first exon of the COX1 gene. We describe here the first mutant of P. anserina that has the alpha sequence precisely deleted and whose cytochrome c oxidase activity is identical to that of wild-type cells. The integration site of the intron is slightly modified, and this change prevents efficient homing of intron alpha. We show here that this mutant displays a senescence syndrome similar to that of the wild type and that its life span is increased about twofold. The introduction of a related group II intron into the mitochondrial genome of the mutant does not restore the wild-type life span. These data clearly demonstrate that intron alpha is not the specific senescence factor but rather an accelerator or amplifier of the senescence process. They emphasize the role that intron alpha plays in the instability of the mitochondrial chromosome and the link between this instability and longevity. Our results strongly support the idea that in Podospora, "immortality" can be acquired not by the absence of intron alpha but rather by the lack of active cytochrome c oxidase. 相似文献
96.
97.
Diani AR Sawada G Wyse B Murray FT Khan M 《American journal of physiology. Endocrinology and metabolism》2004,286(1):E116-E122
Thiazolidinediones may slow the progression of type 2 diabetes by preserving pancreatic beta-cells. The effects of pioglitazone (PIO) on structure and function of beta-cells in KKA(y), C57BL/6J ob/ob, and C57BL/KsJ db/db mice (genetic models of type 2 diabetes) were examined. ob/ob (n = 7) and db/db (n = 9) mice were randomly assigned to 50-125 mg.kg body wt-1.day-1 of PIO in chow beginning at 6-10 wk of age. Control ob/ob (n = 7) and db/db mice (n = 9) were fed chow without PIO. KKA(y) mice (n = 15) were fed PIO daily at doses of 62-144 mg.kg body wt-1.day-1. Control KKA(y) mice (n = 10) received chow without PIO. Treatment continued until euthanasia at 14-26 wk of age. Blood was collected at baseline (before treatment) and just before euthanasia and was analyzed for glucose, glycosylated hemoglobin, and plasma insulin. Some of the splenic pancreas of each animal was resected and partially sectioned for light or electron microscopy. The remainder of the pancreas was assayed for insulin content. Compared with baseline and control groups, PIO treatment significantly reduced blood glucose and glycosylated hemoglobin levels. Plasma insulin levels decreased significantly in ob/ob mice treated with PIO. All groups treated with PIO exhibited significantly greater beta-cell granulation, evidence of reduced beta-cell stress, and 1.5- to 15-fold higher levels of pancreatic insulin. The data from these studies suggest that comparable effects would be expected to slow the progression of type 2 diabetes, either delaying or possibly preventing progression to an insulin-dependent state. 相似文献
98.
99.
Carbonylation of glycolytic proteins is a key response to drug-induced oxidative stress and apoptosis 总被引:2,自引:0,他引:2
Recent work has highlighted the importance of protein post-translational modifications such as phosphorylation (enzymatic) and nitrosylation (nonenzymatic) in the early stages of apoptosis. In this study, we have investigated the levels of protein carbonylation, a nonenzymatic protein modification that occurs in conditions of cellular oxidative stress, during etopside-induced apoptosis of HL60 cells. Within 1 h of VP16 treatment, a number of proteins underwent carbonylation due to oxidative stress. This was inhibited by the antioxidant N-acetyl-L-cysteine. Among the proteins found to be carbonylated were glycolytic enzymes. Subsequently, we found that the rate of glycolysis was significantly reduced, probably due to a carbonylation mediated reduction in enzymatic activity of glycolytic enzymes. Our work demonstrates that protein carbonylation can be rapidly induced through cytotoxic drug treatment and may specifically inhibit the glycolytic pathway. Given the importance of glycolysis as a source of cellular ATP, this has severe implications for cell function. 相似文献
100.
Christoph?Kluge Thorsten?Seidel Susanne?Bolte Shanti?S?Sharma Miriam?Hanitzsch Beatrice?Satiat-Jeunemaitre Joachim?Ro? Markus?Sauer Dortje?Golldack Karl-Josef?DietzEmail author 《BMC cell biology》2004,5(1):29