全文获取类型
收费全文 | 3202篇 |
免费 | 175篇 |
出版年
2023年 | 14篇 |
2022年 | 29篇 |
2021年 | 64篇 |
2020年 | 45篇 |
2019年 | 52篇 |
2018年 | 72篇 |
2017年 | 70篇 |
2016年 | 101篇 |
2015年 | 143篇 |
2014年 | 161篇 |
2013年 | 243篇 |
2012年 | 271篇 |
2011年 | 261篇 |
2010年 | 174篇 |
2009年 | 141篇 |
2008年 | 248篇 |
2007年 | 213篇 |
2006年 | 224篇 |
2005年 | 204篇 |
2004年 | 167篇 |
2003年 | 160篇 |
2002年 | 117篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 21篇 |
1998年 | 11篇 |
1997年 | 18篇 |
1996年 | 15篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1961年 | 3篇 |
排序方式: 共有3377条查询结果,搜索用时 31 毫秒
101.
102.
The macroinvertebrate assemblages in an artificial habitat, the settling basin of a hydroelectric power plant, were investigated and compared with those in a natural habitat, riffles in a nearby river. This study showed that macroinvertebrate density was much higher in the settling basin than in the riffles. Macroinvertebrate assemblage composition differed between the settling basin and the riffles. The difference was probably due to the widespread bryophyte beds in the settling basin. Cincticostella, Brachycentrus, Ephmerella, and chironomid midges, which are usually abundant in bryophyte beds, were present at much higher densities in the settling basin. Cheumatopsyche and Taeniopterygidae were also present at higher densities in the settling basin than in the natural riffles. In contrast, Epeorus was present at lower density in the settling basin than in the natural riffles. This study suggests that the settling basin increases β-diversity in riverine ecosystems. 相似文献
103.
Junichiro Kishi Shinsuke Inuki Natsumi Hirata Emi Kashiwabara Daisuke Yoshidome Osamu Ichihara Yukari Fujimoto 《Bioorganic & medicinal chemistry letters》2019,29(8):970-973
Abstract
CD1d is a non-polymorphic antigen-presenting glycoprotein that recognizes glycolipids as ligands. Ligands bind to the hydrophobic grooves of CD1d, and the resulting ligand-CD1d complexes activate natural killer T (NKT) cells by means of T cell receptor recognition, leading to the secretion of various cytokines. However, details of the ligand recognition mechanism of a large hydrophobic ligand binding pocket and the relationship between cytokine induction and ligand structure are unclear. We report the synthesis of α-GalCer derivatives containing a Bz amide group having various substituting groups in the ceramide moiety, and the analysis of the structure-activity relationships. The assays reveal that the Bz amide-containing CD1d ligands function as NKT cell modulators displaying Th2 cytokine biasing responses. Furthermore, molecular dynamics simulation studies suggest that the phenyl groups can interact with the aromatic amino acid residues in the lipid binding pocket of CD1d. 相似文献104.
105.
Toshihiro Hamajima Fumie Takahashi Koji Kato Yukihito Sugano Susumu Yamaki Daisuke Suzuki Ayako Moritomo Satoshi Kubo Koji Nakamura Kaoru Yamagami Koji Yokoo Hidehiko Fukahori 《Bioorganic & medicinal chemistry》2019,27(6):1056-1064
Chemical optimization of the 5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine (THPP) scaffold was conducted with a focus on cellular potency while maintaining high selectivity against PI3K isoforms. Compound 11f was identified as a potent, highly selective and orally available PI3Kδ inhibitor. In addition, 11f exhibited efficacy in an in vivo antibody production model. The desirable drug-like properties and in vivo efficacy of 11f suggest its potential as a drug candidate for the treatment of autoimmune diseases and leukocyte malignancies. 相似文献
106.
Nurmaya Effendi Kenji Mishiro Takeshi Takarada Daisuke Yamada Ryuichi Nishii Kazuhiro Shiba Seigo Kinuya Akira Odani Kazuma Ogawa 《Bioorganic & medicinal chemistry》2019,27(2):383-393
Several malignant tumors and fibrotic diseases are associated with PDGFRβ overexpression and excessive signaling, making this receptor attractive for molecular targeting and imaging approaches. A series of benzo[d]imidazole-quinoline derivatives were designed and synthesized to develop radioiodinated compounds as PDGFRβ-specific imaging probes. The structure activity relationship (SAR) evaluation of the designed compounds was performed. Among them, 2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]-8-(piperazin-1-yl)quinoline (5a) and 4-{2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinolin-8-yl}morpholine (5d) exhibited a relatively high PDGFRβ-TK inhibitory potency, whereas iodinated 5a derivative 5-iodo-2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]-8-(piperazin-1-yl)quinoline (8) exhibited a superior inhibitory potency as PDGFRβ inhibitor than iodinated 5d derivative 4-{5-iodo-2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinolin-8-yl}morpholine (11). Furthermore, [125I]8 and [125I]11 were synthesized and evaluated for PDGFRβ radioligand ability, both in vitro and in vivo. Cellular uptake experiments showed that [125I]8 had a higher uptake in BxPC3-luc cells as PDGFRβ-positive cells than [125I]11. Incubation of [125I]8 after pretreatment of PDGFRβ ligands significantly reduced the uptake of [125I]8. In biodistribution experiments using tumor-bearing mice, [125I]8 accumulation in the tumor 1?h postinjection was higher than that of the benzo[d]imidazol-quinoline derivative [125I]IIQP, used in our previous research. These results indicate that [125I]8 could be a promising PDGFRβ imaging agent. Although its clinical application requires further structural modifications, the results obtained in this research may be useful for the development of PDGFRβ-specific radioligands. 相似文献
107.
With more than 40,000 species, Malacostraca is the most diverse crustacean class. Most malacostracans are gonochoristic, but simultaneous hermaphrodites are also known. Tanaidacea is one of two malacostracan orders that includes simultaneously hermaphroditic species; so far, simultaneous hermaphroditism has been confirmed externally and internally in only two tanaidacean species, both in the genus Apseudes (Apseudidae). Here we show, through external and internal morphological observations of fixed specimens, that the apseudid Falsapseudes bowmani is a simultaneous hermaphrodite, making Falsapseudes the second tanaidacean genus in which simultaneous hermaphroditism has been confirmed both externally and internally. In this species, the epistome (a projection on the clypeus) was thick and elongate in large specimens but was thin and spiniform in smaller specimens; the brooding of eggs or embryos was observed only in thin‐epistome individuals, although a pair of ovaries was confirmed in both thick‐ and thin‐epistome individuals. This suggests that individuals with a thick epistome may act as males while also retaining the female reproductive organs. 相似文献
108.
Takashi Yazawa Yoshitaka Imamichi Koh‐ichi Yuhki Junsuke Uwada Daisuke Mikami Masayuki Shimada Kaoru Miyamoto Takeshi Kitano Satoru Takahashi Toshio Sekiguchi Nobuo Suzuki Md. Rafiqul Islam Khan Fumitaka Ushikubi Akihiro Umezawa Takanobu Taniguchi 《Molecular reproduction and development》2019,86(7):786-797
109.
Koyama Satoshi Fujita Hiroyuki Shimosato Takeshi Kamijo Aki Ishiyama Yasufumi Yamamoto Eri Ishii Yoshimi Hattori Yukako Hagihara Maki Yamazaki Etsuko Tomita Naoto Nakajima Hideaki 《Probiotics and antimicrobial proteins》2019,11(1):295-298
Probiotics and Antimicrobial Proteins - Probiotic-rich foods are consumed without much restriction. We report here, a case of septic shock caused by yogurt derived Lactobacillus species in a... 相似文献
110.
Kengo Sasaki Jun Inoue Daisuke Sasaki Namiko Hoshi Tomokazu Shirai Itsuko Fukuda Takeshi Azuma Akihiko Kondo Ro Osawa 《Biotechnology journal》2019,14(5)
Compositional alteration of the gut microbiota is associated with ulcerative colitis (UC). Here, a model culture system is established for the in vitro human colonic microbiota of UC, which will be helpful for determining medical interventions. 16S ribosomal RNA sequencing confirms that UC models are successfully developed from fecal inoculum and retain the bacterial species biodiversity of UC feces. The UC models closely reproduce the microbial components and successfully preserve distinct clusters from the healthy subjects (HS), as observed in the feces. The relative abundance of bacteria belonging to the family Lachnospiraceae significantly decreases in the UC models compared to that in HS, as observed in the feces. The system detects significantly lower butyrogenesis in the UC models than that in HS, correlating with the decreased abundance of Lachnospiraceae. Interestingly, the relative abundance of Lachnospiraceae does not correlate with disease activity (defined as partial Mayo score), suggesting that Lachnospiraceae persists in UC patients at a decreased level, irrespective of the alteration in disease activity. Moreover, the system shows that administration of Clostridium butyricum MIYAIRI restores butyrogenesis in the UC model. Hence, the model detects deregulation in the intestinal environment in UC patients and may be useful for simulating the effect of probiotics. 相似文献