全文获取类型
收费全文 | 3112篇 |
免费 | 163篇 |
国内免费 | 3篇 |
专业分类
3278篇 |
出版年
2022年 | 12篇 |
2021年 | 20篇 |
2020年 | 14篇 |
2019年 | 18篇 |
2018年 | 38篇 |
2017年 | 29篇 |
2016年 | 45篇 |
2015年 | 68篇 |
2014年 | 90篇 |
2013年 | 244篇 |
2012年 | 145篇 |
2011年 | 176篇 |
2010年 | 102篇 |
2009年 | 110篇 |
2008年 | 179篇 |
2007年 | 192篇 |
2006年 | 219篇 |
2005年 | 204篇 |
2004年 | 202篇 |
2003年 | 196篇 |
2002年 | 192篇 |
2001年 | 31篇 |
2000年 | 28篇 |
1999年 | 32篇 |
1998年 | 32篇 |
1997年 | 43篇 |
1996年 | 40篇 |
1995年 | 51篇 |
1994年 | 32篇 |
1993年 | 46篇 |
1992年 | 41篇 |
1991年 | 20篇 |
1990年 | 24篇 |
1989年 | 19篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 12篇 |
1985年 | 29篇 |
1984年 | 21篇 |
1983年 | 29篇 |
1982年 | 30篇 |
1981年 | 29篇 |
1980年 | 26篇 |
1979年 | 10篇 |
1978年 | 20篇 |
1977年 | 15篇 |
1976年 | 12篇 |
1975年 | 9篇 |
1974年 | 11篇 |
1973年 | 13篇 |
排序方式: 共有3278条查询结果,搜索用时 0 毫秒
101.
Hiroki Kumamoto Hiroyuki Hayakawa Hiromichi Tanaka Satoru Shindoh Keisuke Kato Tadashi Miyasaka 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):15-27
Abstract Based on the recently developed lithiation-mediated stannyl migration of 6-chloropurine derivatives, 2-iodocordycepin was prepared from cordycepin. The reaction of this compound with terminal alkynes was carried out to synthesize a series of 2-alkynyl derivatives. The vasodilating effect of these compounds was evaluated. 相似文献
102.
Atsushi Kittaka Naoki Yamada Hiromichi Tanaka Kazuo T. Nakamura Tadashi Miyasaka 《Nucleosides, nucleotides & nucleic acids》2013,32(9):1447-1457
Abstract A vinyl radical generated from a 6-chloro-9-(2-deoxy--d eryrhro-pent-l-enofuranosyl)-8-(2,2-dibromovinyl) purine effected cyclization either at the 1′-or at the 2′-position. The result is discussed in comparison with our previous study of the corresponding uracil derivative. 相似文献
103.
Tadashi Itagaki Naomi Motoyoshi Hiroko Kobayashi Yoshio Ogawa Dai Hirose Norio Inokuchi 《Mycoscience》2013,54(3):188-197
A gene encoding a ribonuclease T2 (RNase T2) family enzyme, RNHe30, was cloned from Hericium erinaceum by PCR. The deduced amino acid sequence from the complimentary DNA (cDNA) (1074 bp) encodes a 302-aa protein (RNase He30) that has the consensus amino acid sequences of RNase T2 family enzymes including the putative signal peptide. The presence of five introns in the genomic DNA was confirmed by comparison of the cDNA and genomic DNA sequences. The promoter region contains a putative CAAT box and a consensus TATA box. Genes coding homologous enzymes were also identified in various other basidiomycetes. A phylogenetic tree of RNase T2s from these fungi was constructed from a multiple alignment of the deduced amino acid sequences. The tree showed that the enzymes were divided into two main groups. 相似文献
104.
We examined complex geographical patterns in the morphology of a kleptoparasitic spider, Argyrodes kumadai, across its distributional range in Japan. To disentangle biotic and abiotic factors underlying morphological variation, latitudinal trends were investigated in two traits, body size and relative leg length, across separate transition zones for host use and voltinism. Statistical analyses revealed complex sawtooth clines. Adult body size dramatically changed at the transition zones for host use and voltinism, and exhibited a latitudinal decline following the converse to Bergmann’s cline under the same host use and voltinism in both sexes. A similar pattern was observed for relative leg length in females but not in males. A genetic basis for a part of observed differences in morphology was supported by a common-garden experiment. Our data suggest that local adaptation to factors other than season length such as resource availability (here associated with host use) obscures underlying responses to latitude. 相似文献
105.
Tae Mogami Naho Yokota Mikiko Asai-Sato Roppei Yamada Shiro Koizume Yuji Sakuma Mitsuyo Yoshihara Yoshiyasu Nakamura Yasuo Takano Fumiki Hirahara Yohei Miyagi Etsuko Miyagi 《PloS one》2013,8(11)
Ovarian clear cell adenocarcinoma (CCC) is the second most common subtype of ovarian cancer after high-grade serous adenocarcinomas. CCC tends to develop resistance to the standard platinum-based chemotherapy, and has a poor prognosis when diagnosed in advanced stages. The ANXA4 gene, along with its product, a Ca++-binding annexin A4 (ANXA4) protein, has been identified as the CCC signature gene. We reported two subtypes of ANXA4 with different isoelectric points (IEPs) that are upregulated in CCC cell lines. Although several in vitro investigations have shown ANXA4 to be involved in cancer cell proliferation, chemoresistance, and migration, these studies were generally based on its overexpression in cells other than CCC. To elucidate the function of the ANXA4 in CCC cells, we established CCC cell lines whose ANXA4 expressions are stably knocked down. Two parental cells were used: OVTOKO contains almost exclusively an acidic subtype of ANXA4, and OVISE contains predominantly a basic subtype but also a detectable acidic subtype. ANXA4 knockdown (KO) resulted in significant growth retardation and greater sensitivity to carboplatin in OVTOKO cells. ANXA4-KO caused significant loss of migration and invasion capability in OVISE cells, but this effect was not seen in OVTOKO cells. We failed to find the cause of the different IEPs of ANXA4, but confirmed that the two subtypes are found in clinical CCC samples in ratios that vary by patient. Further investigation to clarify the mechanism that produces the subtypes is needed to clarify the function of ANXA4 in CCC, and might allow stratification and improved treatment strategies for patients with CCC. 相似文献
106.
Kazuyo Yasuda Toshihiko Torigoe Rena Morita Takahumi Kuroda Akari Takahashi Junichi Matsuzaki Vitaly Kochin Hiroko Asanuma Tadashi Hasegawa Tsuyoshi Saito Yoshihiko Hirohashi Noriyuki Sato 《PloS one》2013,8(8)
Cancer stem-like cells (CSCs)/cancer-initiaiting cells (CICs) are defined as a small population of cancer cells that have self-renewal capacity, differentiation potential and high tumor-initiating ability. CSCs/CICs of ovarian cancer have been isolated by side population (SP) analysis, ALDEFLUOR assay and using cell surface markers. However, these approaches are not definitive markers for CSCs/CICs, and it is necessary to refine recent methods for identifying more highly purified CSCs/CICs. In this study, we analyzed SP cells and aldehyde dehydrogenese bright (ALDHBr) cells from ovarian cancer cells. Both SP cells and ALDHBr cells exhibited higher tumor-initiating ability and higher expression level of a stem cell marker, sex determining region Y-box 2 (SOX2), than those of main population (MP) cells and ALDHLow cells, respectively. We analyzed an SP and ALDHBr overlapping population (SP/ALDHBr), and the SP/ALDHBr population exhibited higher tumor-initiating ability than that of SP cells or ALDHBr cells, enabling initiation of tumor with as few as 102 cells. Furthermore, SP/ADLHBr population showed higher sphere-forming ability, cisplatin resistance, adipocyte differentiation ability and expression of SOX2 than those of SP/ALDHLow, MP/ALDHBr and MP/ALDHLow cells. Gene knockdown of SOX2 suppressed the tumor-initiation of ovarian cancer cells. An SP/ALDHBr population was detected in several gynecological cancer cells with ratios of 0.1% for HEC—1 endometrioid adenocarcinoma cells to 1% for MCAS ovary mucinous adenocarcinoma cells. Taken together, use of the SP and ALDHBr overlapping population is a promising approach to isolate highly purified CSCs/CICs and SOX2 might be a novel functional marker for ovarian CSCs/CICs. 相似文献
107.
108.
Yui Shimizu Kazue Ohishi Rintaro Suzuki Yuko Tajima Tadasu Yamada Yuka Kakizoe Takeharu Bando Yoshihiro Fujise Hajime Taru Tsukasa Murayama Tadashi Maruyama 《Microbiology and immunology》2013,57(9):624-632
Morbillivirus infection is a severe threat to marine mammals. Mass die‐offs caused by this infection have repeatedly occurred in bottlenose dolphins (Turiops truncatus) and striped dolphins (Stenella coeruleoalba), both of which belong to the family Delphinidae, but not in other cetaceans. However, it is unknown whether sensitivity to the virus varies among cetacean species. The signaling lymphocyte activation molecule (SLAM) is a receptor on host cells that allows morbillivirus invasion and propagation. Its immunoguloblin variable domain‐like (V) region provides an interface for the virus hemagglutinin (H) protein. In this study, variations in the amino acid residues of the V region of 26 cetacean species, covering almost all cetacean genera, were examined. Three‐dimensional (3D) models of them were generated in a homology model using the crystal structure of the marmoset SLAM and measles virus H protein complex as a template. The 3D models showed 32 amino acid residues on the interface that possibly bind the morbillivirus. Among the cetacean species studied, variations were found at six of the residues. Bottlenose and striped dolphins have substitutions at five positions (E68G, I74V, R90H, V126I, and Q130H) compared with those of baleen whales. Three residues (at positions 68, 90 and 130) were found to alternate electric charges, possibly causing changes in affinity for the virus. This study shows a new approach based on receptor structure for assessing potential vulnerability to viral infection. This method may be useful for assessing the risk of morbillivirus infection in wildlife. 相似文献
109.
Naoko Sekino‐Suzuki Kohei Yuyama Toshiaki Miki Mizuho Kaneda Hidenori Suzuki Naomasa Yamamoto Tadashi Yamamoto Chitose Oneyama Masato Okada Kohji Kasahara 《Journal of neurochemistry》2013,124(4):514-522
The association of gangliosides with specific proteins in the central nervous system was examined by coimmunoprecipitation with an anti‐ganglioside antibody. The monoclonal antibody to the ganglioside GD3 (R24) immunoprecipitated the Csk (C‐terminal src kinase)‐binding protein (Cbp). Sucrose density gradient analysis showed that Cbp of rat cerebellum was detected in detergent‐resistant membrane (DRM) raft fractions. R24 treatment of the rat primary cerebellar cultures induced Lyn activation and tyrosine phosphorylation of Cbp. Treatment with anti‐ganglioside GD1b antibody also induced tyrosine phosphorylation. Furthermore, over‐expressions of Lyn and Cbp in Chinese hamster ovary (CHO) cells resulted in tyrosine 314 phosphorylation of Cbp, which indicates that Cbp is a substrate for Lyn. Immunoblotting analysis showed that the active form of Lyn and the Tyr314‐phosphorylated form of Cbp were highly accumulated in the DRM raft fraction prepared from the developing cerebellum compared with the DRM raft fraction of the adult one. In addition, Lyn and the Tyr314‐phosphorylated Cbp were highly concentrated in the growth cone fraction prepared from the developing cerebellum. Immunoelectron microscopy showed that Cbp and GAP‐43, a growth cone marker, are localized in the same vesicles of the growth cone fraction. These results suggest that Cbp functionally associates with gangliosides on growth cone rafts in developing cerebella. 相似文献
110.
Shota Tanifuji Megumi Funakoshi-Tago Fumihito Ueda Tadashi Kasahara Sumiko Mochida 《The Journal of biological chemistry》2013,288(26):19050-19059
Presynaptic nerve terminals must maintain stable neurotransmission via synaptic vesicle membrane recycling despite encountering wide fluctuations in the number and frequency of incoming action potentials (APs). However, the molecular mechanism linking variation in neuronal activity to vesicle trafficking is unknown. Here, we combined genetic knockdown and direct physiological measurements of synaptic transmission from paired neurons to show that three isoforms of dynamin, an essential endocytic protein, work individually to match vesicle reuse pathways, having distinct rate and time constants with physiological AP frequencies. Dynamin 3 resupplied the readily releasable pool with slow kinetics independently of the AP frequency but acted quickly, within 20 ms of the incoming AP. Under high-frequency firing, dynamin 1 regulated recycling to the readily releasable pool with fast kinetics in a slower time window of greater than 50 ms. Dynamin 2 displayed a hybrid response between the other isoforms. Collectively, our findings show how dynamin isoforms select appropriate vesicle reuse pathways associated with specific neuronal firing patterns. 相似文献