全文获取类型
收费全文 | 6036篇 |
免费 | 285篇 |
国内免费 | 7篇 |
出版年
2023年 | 10篇 |
2022年 | 42篇 |
2021年 | 64篇 |
2020年 | 31篇 |
2019年 | 50篇 |
2018年 | 90篇 |
2017年 | 59篇 |
2016年 | 125篇 |
2015年 | 172篇 |
2014年 | 203篇 |
2013年 | 526篇 |
2012年 | 353篇 |
2011年 | 380篇 |
2010年 | 228篇 |
2009年 | 236篇 |
2008年 | 391篇 |
2007年 | 413篇 |
2006年 | 368篇 |
2005年 | 409篇 |
2004年 | 388篇 |
2003年 | 411篇 |
2002年 | 326篇 |
2001年 | 56篇 |
2000年 | 31篇 |
1999年 | 66篇 |
1998年 | 87篇 |
1997年 | 72篇 |
1996年 | 63篇 |
1995年 | 54篇 |
1994年 | 56篇 |
1993年 | 60篇 |
1992年 | 44篇 |
1991年 | 34篇 |
1990年 | 36篇 |
1989年 | 24篇 |
1988年 | 28篇 |
1987年 | 14篇 |
1986年 | 17篇 |
1985年 | 20篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1982年 | 31篇 |
1981年 | 48篇 |
1980年 | 28篇 |
1979年 | 20篇 |
1978年 | 13篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1975年 | 17篇 |
1973年 | 12篇 |
排序方式: 共有6328条查询结果,搜索用时 15 毫秒
991.
Yoshihiro Itoh Satoshi Horiuchi Kenji Yamamoto 《Photochemical & photobiological sciences》2005,4(10):835-839
A series of benzyl-containing ammonium salts, p-alkylbenzyltrimethylammonium halides (C(n)BA: 1a-c) and alkylbenzyldimethylammonium halides (C(n)AB: 2a-d), have been prepared and their photodegradabilities in aqueous solutions have been compared. The photolytic decomposition proceeded by heterolytic and homolytic cleavages of the benzyl-nitrogen bond. The conversion yields were almost the same for all surfactants, whereas the product yields were slightly dependent on the alkyl-chain length. After irradiation, C(8)BA (1b) and C(12)BA (1c) were converted to non-surfactants, whereas C(12)AB (2c) and C(16)AB (2d) still remained surface-active. Their solution properties were concomitantly changed. 相似文献
992.
Celina M Haraguchi Tadashi Mabuchi Shuji Hirata Tomoko Shoda Kazuhiko Hoshi Kenji Akasaki Sadaki Yokota 《The journal of histochemistry and cytochemistry》2005,53(4):455-465
We investigated the localization of several markers for lysosomes and aggresomes in the chromatoid bodies (CBs) by immunoelectron microscopy. We found so-called aggresomal markers such as Hsp70 and ubiquitin in the core of the CBs and vimentin and proteasome subunit around the CBs. Ubiquitin-conjugating enzyme (E2) was also found in the CBs. In tubulovesicular structures surrounding the CBs, lysosomal markers were detected but an endoplasmic reticulum retention signal (KDEL) was not. Moreover, proteins located in each subcellular compartment, including the cytosol, mitochondria, and nucleus, were detected in the CBs. Signals for cytochrome oxidase I (COXI) coded on mitochondrial DNA were also found in the CBs. Quantitative analysis of labeling density showed that all proteins examined were concentrated in the CBs to some extent. These results show that the CBs have some aggresomal features, suggesting that they are not a synthetic site as proposed previously but a degradation site where unnecessary DNA, RNA, and proteins are digested. 相似文献
993.
Mori Toyoki Takeuchi Tadayoshi Ohura Makoto Miyakoda Goro Fujiki Hiroyuki Orito Kensuke Yoshida Kenji Hirano Takahiro Yamamura Yoshitaka Sumida Takumi Nakaya Yutaka Satake Hiromu Hata Fumiaki 《Molecular and cellular biochemistry》1998,178(1-2):335-343
Pranidipine, a new calcium channel modulator, prolonged endothelium-dependent relaxation induced by acetylcholine in a aortic ring preparation, contracted with prostaglandin F2. This action was not shared by amlodipine. The effect was not modified by indomethacin, suggesting that the action of pranidipine does not involve prostanoid metabolism. NG-nitro-L-arginine completely prevented the action of Pranidipine. The drug affected neither nitric oxide (NO) synthase activity nor the level of cyclic GMP in the vessel. Pranidipine did not affect the sensitivity of the contractile proteins to calcium. Pranidipine also did not alter cyclic GMP-induced relaxation in a-toxinskinned vascular preparations. Pranidipine also prolonged glyceryl trinitrate-induced relaxation in the endothelium denuded rat aorta. Furthermore, pranidipine enhanced relaxation of the aorta induced by glyceryl trinitrate even in the presence of methylene blue, a guanylyl cyclase inhibitor. This action was not modified by iberiotoxin or by charybdotoxin, two inhibitors of the calciumactivated potassium channel. The results strongly suggest that pranidipine enhances cyclic GMPindependent NO-induced relaxation of smooth muscle by a mechanism other than through NOinduced hyperpolarization. These effects were in direct contrast to amlodipine, another new 1,4dihydropyridine calcium antagonist. 相似文献
994.
One hundred sixty-six isolates of Fusarium spp. from domestic cereal grains, feed, and other sources were examined for their ability to produce zearalenone on autoclaved moist rice grains. They belonged to the following species (number of producers/number tested): F. roseum (9/28), F. roseum (Culmorum) (3/4), F. roseum (Gibbosum) (2/5), F. roseum (Avenaceum) (1/2), F. roseum (Scirpi) (0/1), F. tricinctum (1/4), F. tricinctum (Sporotrichiella) (0/7), F. lateritium (1/1), F. episphaeria (0/2), F. moniliforme (0/3), F. oxysporum (0/12), F. rigidiusculum (0/4), F. solani (0/4), F. splendens (0/1), F. nivale (0/2), and Fusarium spp. (15/86). Zearalenone was isolated from molded rice by ethanol extraction and purified by column chromatography. Selected isolates of F. roseum M-3-2 and F. roseum (Gibbosum) A-O-2 produced 50 to 100 mg of zearalenone per kg of rice. Increased yields (250 to 407 mg/kg of rice) were obtained by F. roseum M-3-2 when the substrate was supplemented with 1% peptone. 相似文献
995.
Production of the Hepatotoxic Chlorine-Containing Peptide by Penicillium islandicum Sopp 总被引:2,自引:2,他引:0 下载免费PDF全文
Twenty-six strains of Penicillium islandicum Sopp were tested for production of a chlorine-containing peptide (Cl-peptide), which is a hepatotoxin. Highest levels of the mycotoxin were produced in a modification of Wickerham medium. The mycotoxin was isolated by adsorption on charcoal and, after washing the charcoal with acetone-water (1:1), was eluted into n-butanol. Further purification was accomplished by gel filtration. Maximum yields were 10 to 20 mg of toxin per liter of culture filtrate. 相似文献
996.
997.
Toshihisa Yashiro Yuki Mitaka Tomonari Nozaki Kenji Matsuura 《Applied Entomology and Zoology》2018,53(2):215-221
Numerous termite species have been introduced outside their native ranges by human transport, and some have become invasive. The dampwood termite Zootermopsis nevadensis (Hagen), which is native to western North America, has been introduced to and become established in Kawanishi City, Hyogo Prefecture, Japan. Zootermopsis nevadensis is subdivided into two subspecies based on cuticular hydrocarbon (CHC) phenotypes: Z. nevadensis nevadensis and Z. nevadensis nuttingi (Haverty and Thorne). Here, we identified Z. nevadensis in Japan as hybrids between the two subspecies. Chemical analysis showed the presence of 7,15-dimethylhenicosane and 5,17-dimethylhenicosane in the CHCs of Z. nevadensis in Japan, corresponding to the CHC phenotype of Z. n. nevadensis. Conversely, all mitochondrial cytochrome c oxidase subunit I sequences of Z. nevadensis in Japan were identical to sequences from Z. n. nuttingi and hybrids between the two subspecies from a native hybrid zone in California, USA. In addition, phylogenetic analysis showed that Z. nevadensis in Japan formed a clade with Z. n. nuttingi and hybrids between the two subspecies. Our results show discordance between the chemical and genetic features of Z. nevadensis in Japan, indicating that individuals of Z. nevadensis in Japan are hybrids between the two subspecies. 相似文献
998.
Lipid-Protein Interplay in Dimerization of Juxtamembrane Domains of Epidermal Growth Factor Receptor
Ryo Maeda Takeshi Sato Kenji Okamoto Masataka Yanagawa Yasushi Sako 《Biophysical journal》2018,114(4):893-903
Transmembrane (TM) helix and juxtamembrane (JM) domains (TM-JM) bridge the extracellular and intracellular domains of single-pass membrane proteins, including epidermal growth factor receptor (EGFR). TM-JM dimerization plays a crucial role in regulation of EGFR kinase activity at the cytoplasmic side. Although the interaction of JM with membrane lipids is thought to be important to turn on EGF signaling, and phosphorylation of Thr654 on JM leads to desensitization, the underlying kinetic mechanisms remain unclear. In particular, how Thr654 phosphorylation regulates EGFR activity is largely unknown. Here, combining single-pair FRET imaging and nanodisc techniques, we showed that phosphatidylinositol 4,5-bis phosphate (PIP2) facilitated JM dimerization effectively. We also found that Thr654 phosphorylation dissociated JM dimers in the membranes containing acidic lipids, suggesting that Thr654 phosphorylation electrostatically prevented the interaction with basic residues in JM and acidic lipids. Based on the single-molecule experiment, we clarified the kinetic pathways of the monomer (inactive state)-to-dimer (active state) transition of JM domains and alteration in the pathways depending on the membrane lipid species and Thr654 phosphorylation. 相似文献
999.
1000.
Masaya Yamaguchi Kenji Satoo Hironori Suzuki Yuko Fujioka Yoshinori Ohsumi Fuyuhiko Inagaki Nobuo N. Noda 《Journal of molecular biology》2018,430(3):249-257
Atg8 is a unique ubiquitin-like protein that is covalently conjugated with a phosphatidylethanolamine through reactions similar to ubiquitination and plays essential roles in autophagy. Atg7 is the E1 enzyme for Atg8, and it activates the C-terminal Gly116 of Atg8 using ATP. Here, we report the crystal structure of Atg8 bound to the C-terminal domain of Atg7 in an unprecedented mode. Atg8 neither contacts with the central β-sheet nor binds to the catalytic site of Atg7, both of which were observed in previously reported Atg7–Atg8 structures. Instead, Atg8 binds to the C-terminal α-helix and crossover loop, thereby changing the autoinhibited conformation of the crossover loop observed in the free Atg7 structure into a short helix and a disordered loop. Mutational analyses suggested that this interaction mode is important for the activation reaction. We propose that Atg7 recognizes Atg8 through multiple steps, which would be necessary to induce a conformational change in Atg7 that is optimal for the activation reaction. 相似文献