全文获取类型
收费全文 | 2756篇 |
免费 | 166篇 |
国内免费 | 4篇 |
出版年
2021年 | 26篇 |
2020年 | 13篇 |
2019年 | 23篇 |
2018年 | 32篇 |
2017年 | 17篇 |
2016年 | 54篇 |
2015年 | 62篇 |
2014年 | 94篇 |
2013年 | 282篇 |
2012年 | 121篇 |
2011年 | 137篇 |
2010年 | 100篇 |
2009年 | 70篇 |
2008年 | 114篇 |
2007年 | 145篇 |
2006年 | 151篇 |
2005年 | 128篇 |
2004年 | 136篇 |
2003年 | 134篇 |
2002年 | 121篇 |
2001年 | 114篇 |
2000年 | 87篇 |
1999年 | 67篇 |
1998年 | 31篇 |
1997年 | 20篇 |
1996年 | 28篇 |
1995年 | 31篇 |
1994年 | 27篇 |
1993年 | 32篇 |
1992年 | 50篇 |
1991年 | 45篇 |
1990年 | 41篇 |
1989年 | 43篇 |
1988年 | 37篇 |
1987年 | 36篇 |
1986年 | 28篇 |
1985年 | 28篇 |
1984年 | 19篇 |
1983年 | 20篇 |
1982年 | 25篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1977年 | 16篇 |
1976年 | 12篇 |
1975年 | 13篇 |
1974年 | 10篇 |
1973年 | 8篇 |
1969年 | 7篇 |
排序方式: 共有2926条查询结果,搜索用时 15 毫秒
1.
Yoshinari Maeda Kiyoshi Yoshimura Hiroto Matsui Yoshitaro Shindo Takao Tamesa Yukio Tokumitsu Noriaki Hashimoto Yoshihiro Tokuhisa Kazuhiko Sakamoto Kouhei Sakai Yutaka Suehiro Yuji Hinoda Koji Tamada Shigefumi Yoshino Shoichi Hazama Masaaki Oka 《Cancer immunology, immunotherapy : CII》2015,64(8):1047-1056
2.
Hiroto Ichishima 《Journal of morphology》2016,277(12):1661-1674
A cribriform plate, a perpendicular plate, and two lateral masses are major components of the ethmoid bone of mammals. Notwithstanding the noticeable bone, virtually sitting in the center of the skull, extensive modifications of the skull of modern cetaceans, especially odontocetes (toothed whales), and the lack of clarity as to what characteristics delimit each element of the ethmoid has made the problem of the nature of the cetacean ethmoid more complicated and elusive than in other, less modified mammals. Furthermore, contention as to whether a perpendicular plate of the ethmoid, or the mesethmoid, exists in all mammals including cetaceans has remained unsettled. In odontocetes, the mesethmoid has been variably identified not only as the osseous nasal septum but also as the mediodorsal region of the posterior wall of the nasal passage below the nasals, as a mass of bone encased by the vomer in front of the osseous nasal cavity at the base of the rostrum, and as a combination of some portions mentioned above. The presence or absence of the mesethmoid in various groups of mammals has attracted the attention of some biologists, and here, I demonstrate that cetaceans have no mesethmoid. The close inspection of the ontogenetic changes of the basicranial elements in cetaceans reveals that a mass of bone ensheathed by the vomer in front, or at the level of the osseous nasal cavity is actually the presphenoid. It is highly likely that in odontocetes the posterior wall of the nasal passages below the nasals consists of the combination of the frontal, the imperforated cribriform plate, the paired ectethmoids, and the vomer, the latter three of which partially concealing the presphenoid dorsally and laterally as the ontogeny proceeds. In contrast, mysticetes clearly display ethmoturbinates and a cribriform plate, which are morphologically similar to those in terrestrial mammals. J. Morphol. 277:1661–1674, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
3.
Abstract It is well known that facultative intracellular pathogens such as Salmonella suppress the host immune system. In the present study we attempted to clarify the mechanism responsible for the suppression of T-cell proliferation in mice infected with Salmonella typhimurium . The proliferation of murine spleen cells stimulated with a T-cell mitogen such as phytohemagglutinin (PHA) or concanavalin A (ConA) was significantly suppressed when the mice were infected with S. typhimurium , but not with Eschirichia coli . The suppression of T-cell proliferation did not necessarily parallel the level of interleukin-2 (IL-2) secretion, and was not restored by treatment with a calcium ionophore, indomethacin or IL-2. Only phorbol 12-myristate-13 acetate (PMA), an activator of protein kinase C (PKC), caused a slight recovery of cell proliferation with an augmentation of IL-2 secretion. Furthermore, Western blotting using anti-phosphotyrosine antibodies showed that the mitogen-induced tyrosine phosphorylation of 120-, 106-, 94-, 68- and 57-kDa proteins in murine splenic T-cells was inhibited by S. typhimurium infection. Also, the inhibition of tyrosine phosphorylation was not restored by treatment with PMA. These results suggest that the suppression of T-cell proliferation induced by Salmonella infection may be regulated by inhibition of tyrosine phosphorylation in T-cells, although the inhibition is not associated with PKC activation and subsequent IL-2 secretion of T cells. 相似文献
4.
5.
Takeshi Kitahara Keimei Fujimoto Masanao Matsui 《Bioscience, biotechnology, and biochemistry》2013,77(8):1511-1514
The synthesis and biological activities of 2,2-dimethyl-3,3-dichlorocyclopropane carboxylic esters are descrived. 相似文献
6.
7.
The AtXTH28 Gene, a Xyloglucan Endotransglucosylase/Hydrolase, is Involved in Automatic Self-Pollination in Arabidopsis thaliana 总被引:1,自引:0,他引:1
Kurasawa Kasumi; Matsui Akihiro; Yokoyama Ryusuke; Kuriyama Tomoko; Yoshizumi Takeshi; Matsui Minami; Suwabe Keita; Watanabe Masao; Nishitani Kazuhiko 《Plant & cell physiology》2009,50(2):413-422
Successful automatic self-pollination in flowering plants isdependent on the correct development of reproductive organs.In the stamen, the appropriate growth of the filament, whichlargely depends on the mechanical properties of the cell wall,is required to position the anther correctly close to the stigmaat the pollination stage. Xyloglucan endotransglucosylase/hydrolases(XTHs) are a family of enzymes that mediate the constructionand restructuring of xyloglucan cross-links, thereby controllingthe extensibility or mechanical properties of the cell wallin a wide variety of plant tissues. Our reverse genetic analysishas revealed that a loss-of-function mutation of an ArabidopsisXTH family gene, AtXTH28, led to a decrease in capability forself-pollination, probably due to inhibition of stamen filamentgrowth. Our results also suggest that the role of AtXTH28 inthe development of the stamen is not functionally redundantwith its closest paralog, AtXTH27. Thus, our finding indicatesthat AtXTH28 is specifically involved in the growth of stamenfilaments, and is required for successful automatic self-pollinationin certain flowers in Arabidopsis thaliana. 相似文献
8.
LTE1 encodes a homolog of GDP-GTP exchange factors for the Ras superfamily and is required at low temperatures for cell cycle progression at the stage of the termination of M phase inSaccharomyces cerevisiae. We isolated extragenic suppressors which suppress the cold sensitivity oflte1 cells and confer a temperature-sensitive phenotype on cells. Cells mutant for the suppressor alone were arrested at telophase at non-permissive temperatures and the terminal phenotype was almost identical to that oflte1 cells at non-permissive temperatures. Genetic analysis revealed that the suppressor is allelic toCDC15, which encodes a protein kinase. Thecdc15 mutations thus isolated were recessive with regard to the temperature-sensitive phenotype and were dominant with respect to suppression oflte1. We isolatedCDC14 as a low-copy-number suppressor ofcdc15-rlt1.CDC14 encodes a phosphotyrosine phosphatase (PTPase) and is essential for termination of M phase. An extra copy ofCDC14 suppressed the temperature sensitivity ofcdc15-rlt1 cells, but not that ofcdc15-1 cells. In addition, some residues that are essential for the Cdc14 PTPase activity were found to be non-essential for the suppression. These results strongly indicate that Cdc14 possesses dual functions; PTPase activity is needed for one function but not for the other. We postulate that the cooperative action of Cdc14 and Cdc15 plays an essential role in the termination of M phase. 相似文献
9.
Toshio Atsumi Toshitsugu Fukumaru Tomoya Ogawa Masanao Matsui 《Bioscience, biotechnology, and biochemistry》2013,77(11):2621-2626
A novel synthesis of N-acetyllincosamine derivatives (3) and (14) was accomplished. 相似文献
10.