全文获取类型
收费全文 | 5277篇 |
免费 | 355篇 |
国内免费 | 3篇 |
出版年
2022年 | 23篇 |
2021年 | 44篇 |
2020年 | 23篇 |
2019年 | 36篇 |
2018年 | 56篇 |
2017年 | 51篇 |
2016年 | 75篇 |
2015年 | 129篇 |
2014年 | 159篇 |
2013年 | 266篇 |
2012年 | 257篇 |
2011年 | 248篇 |
2010年 | 149篇 |
2009年 | 157篇 |
2008年 | 237篇 |
2007年 | 236篇 |
2006年 | 223篇 |
2005年 | 255篇 |
2004年 | 224篇 |
2003年 | 264篇 |
2002年 | 232篇 |
2001年 | 199篇 |
2000年 | 220篇 |
1999年 | 177篇 |
1998年 | 78篇 |
1997年 | 61篇 |
1996年 | 55篇 |
1995年 | 56篇 |
1994年 | 51篇 |
1993年 | 51篇 |
1992年 | 119篇 |
1991年 | 123篇 |
1990年 | 105篇 |
1989年 | 110篇 |
1988年 | 101篇 |
1987年 | 74篇 |
1986年 | 76篇 |
1985年 | 53篇 |
1984年 | 67篇 |
1983年 | 50篇 |
1982年 | 42篇 |
1981年 | 34篇 |
1980年 | 23篇 |
1979年 | 43篇 |
1978年 | 34篇 |
1977年 | 32篇 |
1976年 | 26篇 |
1974年 | 33篇 |
1971年 | 28篇 |
1970年 | 29篇 |
排序方式: 共有5635条查询结果,搜索用时 15 毫秒
1.
2.
T Tobe S Minoshima S Yamase N H Choi M Tomita N Shimizu 《Cytogenetics and cell genetics》1991,57(4):193-195
SP-40,40 is a serum glycoprotein consisting of two different subunits (alpha and beta) assembled into a dimer by disulfide bonds. Northern blot hybridization, using total RNA from several cell lines, showed that SP-40,40 is expressed in glioblastoma and testicular tumor cells, as well as hepatoma cells. Spot blot hybridization of flow-sorted human chromosomes, using a SP-40,40 cDNA fragment as a probe, localized the gene for SP-40,40 to human chromosome 8. This gene has been given the designation CLI, for complement lysis inhibitor, by the Human Gene Nomenclature Committee. 相似文献
3.
Akihisa Hattori 《Journal of Ethology》2006,24(1):51-57
The distribution patterns of the leathery sea anemone, Heteractis crispa, which contains an algal endosymbiont (zooxanthellae) and anemonefish, were investigated in relation to size distribution on a shallow fringing reef (3.2 ha, 0–4 m depth) in Okinawa, Japan. Individual growth and movements were also examined. Large individuals (>1,000 cm2) inhabited reef edges up to a depth of 4 m, while small anemone (<500 cm2) inhabited shallow reefs including inner reef flats. Individuals rarely moved, and their sizes were significantly correlated with their water depths. Growth of small anemones was negatively correlated with their distance from the reef edge, suggesting that reef edges provide more prey and lower levels of physiological stress. This study suggested that deep reef edges are suitable habitats for H. crispa. Large anemones were inhabited by large Amphiprion perideraion or large Amphiprion clarkii, both of which are effective defenders against anemone predators. Anemones that settle in deep reef edges may enjoy a higher survival rate and attain a large size because of their symbiotic relationship with anemonefish. However, early settlers do not harbor anemonefish. Their mortality rate would be higher in the deep edges than in shallow edges, the complicated topography of which provides refuge. 相似文献
4.
An examination of four species of Cirsium disclosed the presence of two new flavonoids in C. lineare. The structure of one was 5,4′-dihydroxy-6,7,3′-trimethoxyflavone (cirsilineol) 4′-monoglucoside and the other 5,3′,4′-trihydroxy-6,7-dimethoxyflavone (cirsiliol) 4′-monoglucoside. Luteolin 7-glucoside was found in C. suffultum, and pectolinarin and linarin in C. kamtschaticum and C. pectinellum. 相似文献
5.
Hisao Tsukamoto Yoshihiro Kubo David L. Farrens Mitsumasa Koyanagi Akihisa Terakita Yuji Furutani 《The Journal of biological chemistry》2015,290(45):27176-27187
Melanopsins play a key role in non-visual photoreception in mammals. Their close phylogenetic relationship to the photopigments in invertebrate visual cells suggests they have evolved to acquire molecular characteristics that are more suited for their non-visual functions. Here we set out to identify such characteristics by comparing the molecular properties of mammalian melanopsin to those of invertebrate melanopsin and visual pigment. Our data show that the Schiff base linking the chromophore retinal to the protein is more susceptive to spontaneous cleavage in mammalian melanopsins. We also find this stability is highly diversified between mammalian species, being particularly unstable for human melanopsin. Through mutagenesis analyses, we find that this diversified stability is mainly due to parallel amino acid substitutions in extracellular regions. We propose that the different stability of the retinal attachment in melanopsins may contribute to functional tuning of non-visual photoreception in mammals. 相似文献
6.
T Maoka A Arai M Shimizu T Matsuno 《Comparative biochemistry and physiology. B, Comparative biochemistry》1986,83(1):121-124
Racemic mixtures of (3RS, 3'RS)-zeaxanthin were separated into the three optical isomers, (3R, 3'R)-zeaxanthin (1), (3R,3'S;meso)-zeaxanthin (2) and (3S,3'S)-zeaxanthin (3), by converting to their corresponding dibenzoates and by using HPLC on an optical resolution column Sumipax OA-2000. According to this procedure, it has been shown that only (1) is isolated from higher plants, shellfish, starfish, sea squirt, sea cucumber and then examined; on the other hand (1), (2) and (3) are isolated from zeaxanthin fraction of shrimp, fish and turtle examined. This is the first isolation of enantiomeric and meso-zeaxanthin in nature. 相似文献
7.
Akira Shimizu 《Journal of Ethology》1992,10(2):85-102
Anoplius eous Yasumatsu (Hymenoptera, Pompilidae) exhibits some outstanding nesting behavior. Females excavate a unicellular or multicellular
nest in wet ground, or dig a single-celled nest in rotten wood, or build clustered mud cells in narrow spaces between walls
of such substances as wood or vinyl sheets. The latter nest-type has been unknown within the subfamily Pompilinae. Females
prepare a nest-cell before hunting, and construct it further after hunting, leaving the prey near the nest (behavior-formula:
IVPTIOC). They transport their prey backward on the ground, grasping it in their mandibles by any part of the legs, and forward
on the surface film of water or on the ground, grasping it by the middle part of the 1st or 2nd legs. Their only prey is the
adult female semi-aquatic spider,Pardosa pseudoannulata (Lycosidae). These nesting and provisioning behavior patterns are compared with those of other pompilids. The position of
the present species in the behavioral evolution of the Pompilidae is suggested. 相似文献
8.
T Nimura M Okada M Shimizu M Kawabe T Itoh M Iwasaki H Kimura T Takeuchi 《The Annals of physiological anthropology》1990,9(4):329-333
Motorcyclists who work in some offices sometimes complained of coldness, pain and numbness of upper limbs. We studied how to discriminate between vibration syndrome and local fatigue of the motorcyclists. Subjects are 42 motorcyclists of an office in Aichi prefecture. 25 of them held several letters in their left hand when they delivered the letters. They complained of coldness, pain and numbness in the left upper limbs more than in the right limbs (p less than 0.01). We think that it is the local fatigue rather than the disorder of vibration syndrome that causes such symptoms. So it is very important to recognize the existence of local fatigue in order to know how to discriminate between vibration syndrome and local fatigue of the motorcyclists. 相似文献
9.
Masanori Shinzato Mikihiro Shamoto Satoru Hosokawa Chiyuki Kaneko Akido Osada Miyuki Shimizu Asako Yoshida 《Biotechnic & histochemistry》1995,70(3):114-118
The present study shows that Langerhans cells can be differentiated from Interdigitating cells at the light microscopic level. Superficial lymph nodes and skin taken from necropsies and the lymph nodes of dermatopathic lymphadenopathy (DPL) were used for this experiment. Sections of lymph node and skin were embedded using the acetone, methyl benzoate and xylene (AMeX) method and dendritic cells were immunostained with anti S-100 protein antibody (S-100, and OKT-6 (CD1a) using the restaining method. Langerhans cells in the skin were positive for both CD1a and S-100. Dendritic cells positive for both CD1a and S-100, and dendritic cells positive for S-100, but not for CD1a were observed in superficial lymph nodes. In normal superficial lymph nodes, there were more interdigitating cells than Langerhans cells. The majority of the dendritic cells in the DPL were Langerhans cells. We conclude that the S-100 and CD1a positive cells are Langerhans cells, and the S-100 positive-CD1a negative cells are interdigitating cells. 相似文献
10.