全文获取类型
收费全文 | 2477篇 |
免费 | 129篇 |
出版年
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 6篇 |
2019年 | 21篇 |
2018年 | 33篇 |
2017年 | 25篇 |
2016年 | 46篇 |
2015年 | 67篇 |
2014年 | 98篇 |
2013年 | 158篇 |
2012年 | 184篇 |
2011年 | 160篇 |
2010年 | 114篇 |
2009年 | 90篇 |
2008年 | 154篇 |
2007年 | 155篇 |
2006年 | 161篇 |
2005年 | 159篇 |
2004年 | 140篇 |
2003年 | 143篇 |
2002年 | 150篇 |
2001年 | 20篇 |
2000年 | 24篇 |
1999年 | 29篇 |
1998年 | 41篇 |
1997年 | 50篇 |
1996年 | 23篇 |
1995年 | 25篇 |
1994年 | 11篇 |
1993年 | 25篇 |
1992年 | 15篇 |
1991年 | 29篇 |
1990年 | 18篇 |
1989年 | 18篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 18篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1971年 | 5篇 |
排序方式: 共有2606条查询结果,搜索用时 93 毫秒
101.
102.
103.
Yoshinori Yabuki Takashi Nagai Keiya Inao Junko Ono Nobuyuki Aiko Nobutoshi Ohtsuka 《Bioscience, biotechnology, and biochemistry》2016,80(10):2069-2075
Laboratory experiments were performed to determine the sampling rates of pesticides for the polar organic chemical integrative samplers (POCIS) used in Japan. The concentrations of pesticides in aquatic environments were estimated from the accumulated amounts of pesticide on POCIS, and the effect of water temperature on the pesticide sampling rates was evaluated. The sampling rates of 48 pesticides at 18, 24, and 30 °C were obtained, and this study confirmed that increasing trend of sampling rates was resulted with increasing water temperature for many pesticides. 相似文献
104.
Efficient modification of the myostatin gene in porcine somatic cells and generation of knockout piglets 下载免费PDF全文
105.
Two isoforms of chicken melanopsins show blue light sensitivity 总被引:1,自引:0,他引:1
Torii M Kojima D Okano T Nakamura A Terakita A Shichida Y Wada A Fukada Y 《FEBS letters》2007,581(27):5327-5331
Melanopsin is a vertebrate non-visual opsin and functions as a circadian photoreceptor in mammalian retinas. Here we found the expression of two kinds of melanopsin genes in the chicken pineal gland and identified the presence of five isoforms derived from these two genes. Reconstitution of the recombinant proteins with 11-cis-retinal revealed that at least two of these melanopsin protein isoforms can function as blue-sensitive photopigments with absorption maxima at 476-484nm. These values are consistent with maximal sensitivities of action spectra determined from the physiological and behavioral studies on mammalian melanopsins. The melanopsin isoforms found in this study may function as pineal circadian photoreceptors. 相似文献
106.
Ichthyological Research - Two types of ophichthid larvae collected from Japanese coastal waters around Kyushu and Shikoku were identified by DNA barcoding as Ophichthus celebicus (Bleeker 1856) and... 相似文献
107.
Eric O. Walliser Kazushige Tanabe Yoshinori Hikida Kotaro Shirai Bernd R. Schne 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2019,52(3):410-428
Here, we present the first sclerochronological investigation of shells of the gigantic inoceramids Sphenoceramus schmidti and S. sachalinensis from the middle Campanian cold seep carbonate‐bearing strata of the Yezo Basin in Hokkaido (northern Japan). Stable carbon (δ13C) and oxygen (δ18O) isotope values were measured in the aragonitic and calcitic shell layers of both species and compared to those of other co‐occurring benthic (mainly bivalves and gastropods) and demersal molluscs (ammonites). Sedimentological and stable isotope data suggest that these bivalves lived near cold seeps and were exposed to high H2S level in the seawater. The inoceramid shells exhibited higher δ13C and lower δ18O values than the coeval non‐cold seep molluscs. We ascribed the anomalous isotopic pattern to a combination of vital and environmental effects determined by the hosting of chemosymbionts and the exposure to warm interstitial waters. Inoceramid δ13C minima coincided with growth lines and likely reflect changes in nutrient supply by the chemosymbionts. Absolute temperatures estimated from δ18O values of Sphenoceramus schmidti and S. sachalinensis were, on average, ca. 4–5°C warmer than those reconstructed for the non‐seepage environment (19.3 ± 0.7°C). Short‐term δ18O fluctuations of the inoceramid material indicate local temperature ranges of up to 5.2°C, that is four times larger than those reconstructed from the benthic and demersal fauna (1.3°C). In general, our data suggest that the stable carbon and oxygen isotope values of the studied Sphenoceramus spp. were strongly affected by short‐term fluctuations in seepage activity and do not reflect seasonal fluctuations. 相似文献
108.
Sugawara H Inoue T Li C Gotowda M Hibino T Takabe T Kai Y 《Journal of biochemistry》1999,125(5):899-903
Plastocyanin functions as an electron carrier between the cytochrome b6f complex and photosystem I. The crystal structures of the wild-type and E43K/D44K double mutant from the higher plant, Silene, have been determined at 2.0 and 1.75 A resolution, respectively. The wild-type plastocyanin comprises two monomers per asymmetric unit, one of which shows the unusually great distance between the copper ion and the Ndelta1 atom of H87 because of the hydrogen bond network formation between H87 and symmetry-related G10. The root mean square deviation for Ca atoms between the wild-type and mutant plastocyanins is 0.44 A, however, the electrostatic potential maps of their molecular surfaces are remarkably different. The low electron-transfer rate in the E43K/D44K mutant results from the hindrance of electrostatic interactions, not from the structural change due to the mutation. 相似文献
109.
Soeno Y Yajima H Kawamura Y Kimura S Maruyama K Obinata T 《Molecular and cellular biochemistry》1999,190(1-2):125-131
Very long, elastic connectin/titin molecules position the myosin filaments at the center of a sarcomere by linking them to the Z line. The behavior of the connectin filaments during sarcomere formation in differentiating chicken skeletal muscle cells was observed under a fluorescent microscope using the antibodies to the N terminal (located in the Z line), C terminal (M line), and C zone (myosin filament) regions of connectin and was compared to the incorporation of -actinin and myosin into forming sarcomeres. In early stages of differentiating muscle cells, the N terminal region of connectin was incorporated into a stress fiber-like structure (SFLS) together with -actinin to form dots, whereas the C terminal region was diffusely distributed in the cytoplasm. When both the C and N terminal regions formed striations in young myofibrils, the epitope to the C zone of A-band region, that is the center between the A-I junction and the M-line, initially was diffuse in appearance and later formed definite striations. It appears that it took some time for the N and C terminal regions of connectin to form a regular organization in a sarcomere. Thus the two ends of the connectin filaments were first fixed followed by the specific binding of the middle portion onto the myosin filament during sarcomere formation. 相似文献
110.
Yoshinori Asakawa Masao Toyota Tsunematsu Takemoto Claude Suire 《Phytochemistry》1979,18(8):1355-1357
Four novel secoaromadendrane-type sesquiterpene hemiacetals, plagiochilines C, D, E and F, together with the previously known (?)-bicyclogermacrene, have been isolated from the liverwort, Plagiochila asplenioides and their structures have been spectroscopically elucidated. From Plagiochila semidecurrens plagiochilines A and C have been obtained along with (?)-bicyclogermacrene and its related sesquiterpene hydrocarbons. 相似文献