全文获取类型
收费全文 | 2686篇 |
免费 | 172篇 |
出版年
2022年 | 21篇 |
2021年 | 26篇 |
2020年 | 21篇 |
2019年 | 39篇 |
2018年 | 36篇 |
2017年 | 44篇 |
2016年 | 54篇 |
2015年 | 96篇 |
2014年 | 95篇 |
2013年 | 154篇 |
2012年 | 204篇 |
2011年 | 170篇 |
2010年 | 127篇 |
2009年 | 109篇 |
2008年 | 191篇 |
2007年 | 217篇 |
2006年 | 188篇 |
2005年 | 170篇 |
2004年 | 182篇 |
2003年 | 176篇 |
2002年 | 176篇 |
2001年 | 26篇 |
2000年 | 19篇 |
1999年 | 30篇 |
1998年 | 28篇 |
1997年 | 19篇 |
1996年 | 26篇 |
1995年 | 21篇 |
1994年 | 24篇 |
1993年 | 19篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 4篇 |
1969年 | 3篇 |
排序方式: 共有2858条查询结果,搜索用时 15 毫秒
91.
Matsuzaki H Nemoto T Fuchigami M Uehara M Suzuki K Nakamura K 《BioFactors (Oxford, England)》2004,22(1-4):43-46
This study investigated the gender differences in the kidney function of magnesium (Mg)-deficient rats. Male and female rats were fed a control diet or a Mg-deficient diet for 21 d. Mg-deficient diet had no significant effect on kidney calcium (Ca) or phosphorus (P) concentration in male rats, while Ca and P concentrations in female rats were significantly higher in Mg-deficient rats than in the control rats. With regard to indicators of kidney function, no significant differences in creatinine clearance and serum urea nitrogen concentration were observed among the groups. Serum albumin concentrations were significantly lower in rats fed the Mg-deficient diet than in rats fed the control diet. In both sexes, urinary albumin excretion was significantly higher in rats fed the Mg-deficient diet than in rats fed the control diet. Gender differences had no significant influence on creatinine clearance, serum urea nitrogen concentration, serum albumin concentration and urinary albumin excretion. These results suggest that gender differences have no effect on kidney function in Mg-deficient rats under the condition used. 相似文献
92.
Sato N Shibata T Jitsuoka M Ohno T Takahashi T Hirohashi T Kanno T Iwaasa H Kanatani A Fukami T 《Bioorganic & medicinal chemistry letters》2004,14(7):1761-1764
A series of substituted 4-alkoxy-2-aminopyridines 2, which were formally derived from neuropeptide Y1 antagonist 1 by replacing the morpholino portion with alkoxy groups, were synthesized and evaluated as neuropeptide Y Y1 receptor antagonists. Primary structure-activity relationships and identification of potent 4-alkoxy derivatives are described. 相似文献
93.
Noriko Okazaki Reiko Kikuno Reiko Ohara Susumu Inamoto Haruhiko Koseki Shuichi Hiraoka Yumiko Saga Hiroshi Kitamura Tomoko Nakagawa Takahiro Nagase Osamu Ohara Hisashi Koga 《DNA research》2004,11(2):127-135
We have been conducting a mouse cDNA project to predict protein-coding sequences of mouse KIAA-homologous genes since 2001. As an extension of this project, we also started to accumulate mouse cDNA clones homologous to the human FLJ cDNA clones which are another long cDNA resource produced in our institute. We have isolated the cDNA clones from size-fractionated cDNA libraries derived from five different mouse tissues and natural killer T-cells. Although the human FLJ cDNA clones were originally derived from human spleen libraries, one-third of their mouse homologues were obtained from the brain library. We designated these homologues "mFLJ" plus a 5-digit number and herein characterized 110 mFLJ cDNA clones. We assigned an integrity of the CDSs from the comparison of the 110 cDNA clones with the corresponding human FLJ cDNA clones. The average size of the 110 mouse cDNA sequences was 3.8 kb and that of the deduced amino acid sequences from their longest CDS in each cDNA was 663 amino acid residues. Homology and/or motif search against public databases revealed new domains and/or motifs in 26 mFLJ gene products which provide additional speculation regarding the function of FLJ genes. 相似文献
94.
Saeki Y Isono E Oguchi T Shimada M Sone T Kawahara H Yokosawa H Toh-e A 《Genes & genetic systems》2004,79(2):77-86
We constructed polyubiquitin derivatives that contain a tandem repeat of ubiquitins and were insensitive to ubiquitin hydrolases. They were designated tandem ubiquitin (tUb) with the number of repeats, such as tUb2. When tUbs were expressed under the control of the GAL1 promoter in the wild-type yeast strain, growth was strongly inhibited. Under these conditions, the degradation of N-end rule substrates, a UFD substrate and Gcn4 was inhibited, indicating that the tUb inhibits 26S proteasome activity. Consistent with this, tUb binds to the 26S proteasome. We showed that tUb inhibited the in vitro degradation of polyubiquitinylated Sic1 by the 26S proteasome. When tUB6 messenger RNA was injected into Xenopus embryos, cell division was inhibited, suggesting that tUb can be used as a versatile inhibitor of the 26S proteasome. 相似文献
95.
Kon T Tanigawa T Hayamizu K Shen M Tsuji T Naito Y Yoshikawa T 《Redox report : communications in free radical research》2004,9(6):325-330
Singlet oxygen is regarded as contributing to the pathogenesis of various diseases including light-induced skin disorders and inflammatory response. In this study, the correlation between singlet oxygen quenching activity (SOQA) of human serum and blood biochemistry or life-style was evaluated. Healthy volunteers were recruited and carried out a measurement of SOQA by using electron paramagnetic resonance (EPR) and a questionnaire survey about a smoking. It was demonstrated that major quenchers of singlet oxygen in serum are proteins, and small molecular anti-oxidants relatively play a minor role. SOQA of whole sera showed no correlation with protein concentration, but positively correlated with SOQA of small molecular fraction. In vitro studies demonstrated that the decrease of sulfhydryl groups by NO or superoxide significantly attenuated SOQA of albumin. Together, these results may imply that the underlying oxidative condition in each individual influences both small molecular antioxidant states and the sulfhydryl content of serum proteins. SOQA of sera from women with a smoking history was significantly lower compared to non-smoking women, suggesting that the smoking habit impaired the defense mechanism against singlet oxygen. 相似文献
96.
Cell-passage activity is required for the malarial parasite to cross the liver sinusoidal cell layer 总被引:3,自引:1,他引:2
Liver infection is an obligatory step in malarial transmission, but it remains unclear how the sporozoites gain access to the hepatocytes, which are separated from the circulatory system by the liver sinusoidal cell layer. We found that a novel microneme protein, named sporozoite microneme protein essential for cell traversal (SPECT), is produced by the liver-infective sporozoite of the rodent malaria parasite, Plasmodium berghei . Targeted disruption of the spect gene greatly reduced sporozoite infectivity to the liver. In vitro cell invasion assays revealed that these disruptants can infect hepatocytes normally but completely lack their cell passage ability. Their apparent liver infectivity was, however, restored by depletion of Kupffer cells, hepatic macrophages included in the sinusoidal cell layer. These results show that malarial sporozoites access hepatocytes through the liver sinusoidal cell layer by cell traversal motility mediated by SPECT and strongly suggest that Kupffer cells are main routes for this passage. Our findings may open the way for novel malaria transmission-blocking strategies that target molecules involved in sporozoite migration to the hepatocyte. 相似文献
97.
Androgenesis, development from paternal but not maternal chromosomes, can be induced in some organisms including fish, but has not been induced previously in mollusk. In this study we investigated the induction of haploid androgenesis in the Pacific oyster by ultraviolet irradiation and observed nuclear behavior in the androgenetic eggs. Irradiation for 90 seconds at a UV intensity of 72 erg/mm2 per second (6480 erg/mm2) was the optimal dose to achieve haploid androgenesis. The fertilization and development rates of D-shaped larvae decreased with increasing exposure time, and the development of the genetically inactivated eggs terminated before reaching the D-shaped stage. Cytologic observations showed that UV irradiation did not affect germinal vesicle breakdown or chromosomal condensation but caused various nuclear behavioral patterns during meiosis and first mitosis: 21.7% of eggs extruded all maternal chromosomes as 2 or 3 polar bodies, and 59.1% of eggs formed one female pronucleus. The maternally derived nucleus did not participate, or partially participated, in the first karyokinesis. The cytologic evidence demonstrates that the male genome is directing development in haploids produced by UV irradiation. 相似文献
98.
Kimura M Masuda T Yamada K Mitani M Kubota N Kawakatsu N Kishii K Inazu M Kiuchi Y Oguchi K Namiki T 《Bioorganic & medicinal chemistry》2004,12(11):3069-3078
An efficient asymmetric synthesis of the chiral N-(3-chloro-2-hydroxypropyl)anilines (2a and 2b) was achieved through the regioselective ring-opening reaction of chiral epichlorohydrin with aniline. This was applied to an asymmetric synthesis of the enantiomers of 1-[4,4-bis(4-fluorophenyl)butyl]-4-[2-hydroxy-3-(phenylamino)propyl]piperazine 1 as a novel potent dopamine uptake inhibitor. Both enantiomers as trihydrochlorides, 4a.3HCl and 4b.3HCl, could be synthesized in good total yields and optical purities of 100% ee in three steps synthesis, respectively. The absolute configurations of 4a.3HCl and 4b.3HCl were determined using the modified Mosher's method with the related compounds, the intermediates (2a and 2b) and the free bases (4a and 4b). The analytical results indicated that 4a.3HCl and 4b.3HCl have the (S)- and (R)-configuration, respectively, and a series of reactions to provide them proceeded without the apparent influence on the stereochemistry at the chiral centers. In in vitro pharmacological evaluations, 4a.3HCl and 4b.3HCl showed potent dopamine transporter binding affinities, high dopamine, moderate serotonin, and weak norepinephrine uptake inhibitory activities, and 4a.3HCl exhibited a more potent and selective dopamine uptake inhibition over the serotonin or norepinephrine uptake inhibition as compared with 4b.3HCl. An ex vivo evaluation revealed that the oral administrations of both enantiomers at a dose of 30 mg/kg in rats displayed apparent dopamine uptake inhibitory activities and 4a.3HCl had a stronger tendency to inhibit dopamine uptake compared with 4b.3HCl. 相似文献
99.
100.
Okuno T Yamada-Inagawa T Karata K Yamanaka K Ogura T 《Journal of structural biology》2004,146(1-2):148-154
We have established a fluorescence polarization assay system by which degradation of sigma32, a physiological substrate, by FtsH can be monitored spectrometrically. Using the system, it was found that an FtsH hexamer degrades approximately 0.5 molecules of Cy3-sigma32 per min at 42 degrees C and hydrolyzes approximately 140 ATP molecules during the degradation of a single molecule of Cy3-sigma32. Evidence also suggests that degradation of sigma32 proceeds from the N-terminus to the C-terminus. Although FtsH does not have a robust enough unfoldase activity to unfold a tightly folded proteins such as green fluorescent protein, it can unfold proteins with lower [Formula: see text] s such as glutathione S-transferase (Tm = 52 degrees C). 相似文献