全文获取类型
收费全文 | 1739篇 |
免费 | 108篇 |
出版年
2022年 | 9篇 |
2021年 | 22篇 |
2020年 | 13篇 |
2019年 | 21篇 |
2018年 | 22篇 |
2017年 | 27篇 |
2016年 | 37篇 |
2015年 | 39篇 |
2014年 | 58篇 |
2013年 | 123篇 |
2012年 | 92篇 |
2011年 | 92篇 |
2010年 | 55篇 |
2009年 | 47篇 |
2008年 | 84篇 |
2007年 | 73篇 |
2006年 | 85篇 |
2005年 | 67篇 |
2004年 | 51篇 |
2003年 | 77篇 |
2002年 | 61篇 |
2001年 | 63篇 |
2000年 | 55篇 |
1999年 | 57篇 |
1998年 | 30篇 |
1997年 | 20篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 12篇 |
1992年 | 36篇 |
1991年 | 33篇 |
1990年 | 34篇 |
1989年 | 36篇 |
1988年 | 18篇 |
1987年 | 16篇 |
1986年 | 25篇 |
1985年 | 20篇 |
1984年 | 23篇 |
1983年 | 22篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 19篇 |
1978年 | 12篇 |
1974年 | 11篇 |
1973年 | 7篇 |
1972年 | 14篇 |
1968年 | 8篇 |
1967年 | 8篇 |
排序方式: 共有1847条查询结果,搜索用时 499 毫秒
71.
AMP deaminase [EC 3.5.6.4] purified from chicken erythrocytes was inhibited by phytic acid (inositol hexaphosphate), which is the principal organic phosphate in chicken red cells. Kinetic analysis has indicated that this inhibition is of an allosteric type. The estimated Ki value was within the normal range of phytic acid concentration, suggesting that this compound acts as a physiological effector. Divalent cations such as Ca2+ and Mg2+ were shown to affect AMP deaminase by potentiating inhibition by lower concentrations of phytic acid, and by relieving the inhibition at higher concentrations of phytic acid. These results suggests that Ca2+ and Mg2+ can modify the inhibition of AMP deaminase by phytic acid in chicken red cells. 相似文献
72.
73.
74.
75.
Yoshikazu Inoh Yuuki Tsuchiya Yokiko Nakanishi Satoru Yokawa Tadahide Furuno 《Cell biology international》2020,44(4):1068-1075
Cationic liposomes are commonly used as vectors to effectively introduce foreign genes into target cells. In another function, we recently showed that cationic liposomes bound to the mast cell surface suppress the degranulation induced by the cross‐linking of high‐affinity immunoglobulin E receptor in a time‐ and dose‐dependent manner. This suppression is mediated by the impairment of the sustained level of intracellular Ca2+ concentration ([Ca2+]i) via the inhibition of store‐operated Ca2+ entry. Further, we revealed that the mechanism underlying an impaired [Ca2+]i increase is the inhibition of the activation of the phosphatidylinositol 3‐kinase (PI3K)‐Akt pathway. Yet, how cationic liposomes inhibit the PI3K‐Akt pathway is still unclear. Here, we focused on caveolin‐1, a major component of caveolae, which is reported to be involved in the activation of the PI3K‐Akt pathway in various cell lines. In this study, we showed that caveolin‐1 translocated from the cytoplasm to the plasma membrane after the activation of mast cells and colocalized with the p85 subunit of PI3K, which seemed to be essential for PI3K activity. Meanwhile, cationic liposomes suppressed the translocation of caveolin‐1 to the plasma membrane and the colocalization of caveolin‐1 with PI3K p85 also at the plasma membrane. This finding provides new information for the development of therapies using cationic liposomes against allergies. 相似文献
76.
Theoretical models on the movement of colonial animals predict that neighbouring colonies may segregate their foraging areas, and many seabird studies have reported the presence of such segregations. However, these studies have often lacked the appropriate null model to test the effect of neighbouring colonies on foraging areas, especially in small colonies or in short‐ranging species. Here, we examined the foraging areas of Adélie Penguins Pygoscelis adeliae from two neighbouring (2 km apart) colonies by using bird‐borne GPS loggers. The field study was conducted at Hukuro Cove colony (104 pairs) and Mizukuguri Cove colony (338 pairs) in Lützow‐Holm Bay, East Antarctica. We obtained GPS tracks for 504 foraging trips from 48 chick‐rearing Adélie Penguins and quantified the degree of overlap in the foraging areas between two colonies. We also produced simulated movement tracks by using correlated random‐walks assuming no inter‐colony competition and quantified the degree of overlap in the simulated foraging areas. Finally, we compared the results from real GPS tracks with those from simulated tracks to examine the effect of neighbouring colonies on Adélie Penguin movement. The results indicate that the degree of overlap was significantly smaller in real tracks than in simulated tracks. In real tracks, the foraging area of the smaller Hukuro Cove colony extended to the other side of the larger Mizukuguri Cove colony, unlike in simulated tracks. Consequently, we suggest that Adélie Penguins from two neighbouring colonies segregated their foraging areas and that the larger colony appeared to affect the foraging area of the smaller colony. 相似文献
77.
Qinlong Hao Mingjie Zheng Kechao Weng Yumei Hao Yao Zhou Yuchen Lin Feng Gao Ziqi Kou Shoji Kawamura Ke Yao Pinglong Xu Jinghai Chen Jian Zou 《遗传学报》2021,48(1):52-62
Although the unique organization of vertebrate cone mosaics was first described long ago,both their underlying molecular basis and physiological significance are largely unknown.Here,we demonstrate that Crumbs proteins,the key regulators of epithelial apical polarity,establish the planar cellular polarity of photoreceptors in zebrafish.Via heterophilic Crb2a-Crb2b interactions,the apicobasal polarity protein Crb2b restricts the asymmetric planar distribution of Crb2a in photoreceptors.The planar polarized Crumbs proteins thus balance intercellular adhesions and tension between photoreceptors,thereby stabilizing the geometric organization of cone mosaics.Notably,loss of Crb2b in zebrafish induces a nearsightedness-like phenotype in zebrafish accompanied by an elongated eye axis and impairs zebrafish visual perception for predation.These data reveal a detailed mechanism for cone mosaic homeostasis via previously undiscovered apical-planar polarity coordination and propose a pathogenic mechanism for nearsightedness. 相似文献
78.
Motosugi Nanane Nakamura Futoshi Nakajima Souta Takahata Chihiro Kawamura Kazuhiro Morimoto Junko 《Landscape and Ecological Engineering》2021,17(2):95-106
Landscape and Ecological Engineering - There have been many earlier studies of the biodiversity and ecosystem services of abandoned farmlands, but studies of abandoned villages are limited,... 相似文献
79.
Matsumoto Yuuki Kaneita Yoshitaka Jike Maki Osaki Yoneatsu Kanda Hideyuki Higuchi Susumu Itani Osamu Otsuka Yuichiro 《Sleep and biological rhythms》2021,19(3):325-336
Sleep and Biological Rhythms - This study aimed to assess the success of the Japanese government’s “Early to bed, early to rise, and don’t forget your breakfast” (EB, ER,... 相似文献
80.
Taiki Hanzawa Kyohei Shibasaki Takahiro Numata Yukio Kawamura Thierry Gaude Abidur Rahman 《The Plant cell》2013,25(9):3424-3433
High-temperature-mediated adaptation in plant architecture is linked to the increased synthesis of the phytohormone auxin, which alters cellular auxin homeostasis. The auxin gradient, modulated by cellular auxin homeostasis, plays an important role in regulating the developmental fate of plant organs. Although the signaling mechanism that integrates auxin and high temperature is relatively well understood, the cellular auxin homeostasis mechanism under high temperature is largely unknown. Using the Arabidopsis thaliana root as a model, we demonstrate that under high temperature, roots counterbalance the elevated level of intracellular auxin by promoting shootward auxin efflux in a PIN-FORMED2 (PIN2)-dependent manner. Further analyses revealed that high temperature selectively promotes the retrieval of PIN2 from late endosomes and sorts them to the plasma membrane through an endosomal trafficking pathway dependent on SORTING NEXIN1. Our results demonstrate that recycling endosomal pathway plays an important role in facilitating plants adaptation to increased temperature. 相似文献