全文获取类型
收费全文 | 1010篇 |
免费 | 65篇 |
出版年
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 19篇 |
2016年 | 19篇 |
2015年 | 44篇 |
2014年 | 34篇 |
2013年 | 42篇 |
2012年 | 69篇 |
2011年 | 61篇 |
2010年 | 36篇 |
2009年 | 29篇 |
2008年 | 51篇 |
2007年 | 55篇 |
2006年 | 46篇 |
2005年 | 33篇 |
2004年 | 33篇 |
2003年 | 29篇 |
2002年 | 33篇 |
2001年 | 24篇 |
2000年 | 17篇 |
1999年 | 32篇 |
1998年 | 5篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1993年 | 6篇 |
1992年 | 16篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 16篇 |
1988年 | 19篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 9篇 |
1973年 | 4篇 |
1971年 | 6篇 |
1970年 | 10篇 |
1969年 | 4篇 |
排序方式: 共有1075条查询结果,搜索用时 156 毫秒
71.
Nobuhiko?NaritaEmail author Yoshifumi?Nakahara Mamoru?Morimoto Ryosuke?Aoki Shigeru?Suda 《The International Journal of Life Cycle Assessment》2004,9(6):355-359
In 1998, the Japan’s Ministry of Economy, Trade, and Industry (METI) launched a five-year national project entitled ‘Development
of Life Cycle Impact Assessment for Products’ (commonly known as ‘the LCA Project’). The purpose of the project is to develop
common LCA methodology as well as a highly reliable database that can be shared in Japan. Activities over these five years
have resulted in the supply of LCI data on some 250 products. Industrial associations voluntarily provided data. The results
of these activities are currently being made available on the Internet on a trial basis in the form of an LCA database. In
addition, a method entitled ‘Life-cycle Impact assessment Method based on Endpoint modeling (LIME)’ was developed. It is expected
that these results will be widely used in Japan in the future. This paper presents an outline of the results of the research
and development that has been conducted in the LCA Project in Japan. 相似文献
72.
Effect of phytate-removal and deamidation of soybean proteins on calcium absorption in the in situ rats 总被引:1,自引:0,他引:1
Kumagai H Koizumi A Sato N Ishikawa Y Suda A Sakurai H Kumagai H 《BioFactors (Oxford, England)》2004,22(1-4):21-24
Soybean proteins were deamidated by cation-exchange resins after phytate, the inhibitor for calcium absorption from the small intestine, was removed in order to provide the enhancement function of calcium absorption to soybean proteins. About 92% of the phosphorus was removed from the soybean proteins by anion-exchange-resin treatment, indicating that most of the phytate was removed. About 70% of the acid amide was deamidated by cation-exchange-resin treatment, and phytate-removed and deamidated soybean proteins (PrDS) having high calcium binding properties were obtained. PrDS were hydrolyzed by digestive enzymes and their calcium-binding properties and the enhancement function of the calcium absorption from the small intestine of rats were examined. As a result, PrDS retained their high calcium binding properties even after hydrolysis by digestive enzymes. In situ experiments showed that PrDS and their hydrolysates enhanced the calcium absorption from the intestine. 相似文献
73.
Blackwell KA Sorenson JP Richardson DM Smith LA Suda O Nath K Katusic ZS 《American journal of physiology. Heart and circulatory physiology》2004,287(6):H2448-H2453
Oxidative stress has been implicated as an important mechanism of vascular endothelial dysfunction induced by aging. Previous studies suggested that tetrahydrobiopterin (BH4), an essential cofactor of endothelial NO synthase, could be a molecular target for oxidation. We tested the hypothesis that oxidative stress, in particular oxidation of BH4, may contribute to attenuation of endothelium-dependent relaxation in aged mice. Vasomotor function of isolated carotid arteries was studied using a video dimension analyzer. Vascular levels of BH4 and its oxidation products were measured via HPLC. In aged mice (age, 95 +/- 2 wk), endothelium-dependent relaxation to ACh (10(-5) to 10(-9) M) as well as endothelium-independent relaxation to the NO donor diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate, 10(-5) to 10(-9) M) were significantly reduced compared with relaxation detected in young mice (age, 23 +/- 0.5 wk). Incubation of aged mouse carotid arteries with the cell-permeable SOD mimetic Mn(III)tetra(4-benzoic acid)porphyrin chloride normalized relaxation to ACh and DEA-NONOate. Furthermore, production of superoxide anion in aorta and serum levels of amyloid P component, which is the murine analog of C-reactive protein, was increased in old mice. In aorta, neither the concentration of BH4 nor the ratio of reduced BH4 to the oxidation products were different between young and aged mice. Our results demonstrate that in mice, aging impairs relaxation mediated by NO most likely by increased formation of superoxide anion. Oxidation of BH4 does not appear to be an important mechanism underlying vasomotor dysfunction in aged mouse arteries. 相似文献
74.
Tie2/angiopoietin-1 signaling regulates hematopoietic stem cell quiescence in the bone marrow niche 总被引:69,自引:0,他引:69
The quiescent state is thought to be an indispensable property for the maintenance of hematopoietic stem cells (HSCs). Interaction of HSCs with their particular microenvironments, known as the stem cell niches, is critical for adult hematopoiesis in the bone marrow (BM). Here, we demonstrate that HSCs expressing the receptor tyrosine kinase Tie2 are quiescent and antiapoptotic, and comprise a side-population (SP) of HSCs, which adhere to osteoblasts (OBs) in the BM niche. The interaction of Tie2 with its ligand Angiopoietin-1 (Ang-1) induced cobblestone formation of HSCs in vitro and maintained in vivo long-term repopulating activity of HSCs. Furthermore, Ang-1 enhanced the ability of HSCs to become quiescent and induced adhesion to bone, resulting in protection of the HSC compartment from myelosuppressive stress. These data suggest that the Tie2/Ang-1 signaling pathway plays a critical role in the maintenance of HSCs in a quiescent state in the BM niche. 相似文献
75.
Several clinical and laboratory studies have demonstrated electromagnetic interaction between implantable medical devices like pacemakers and cell phones being operated in close proximity. Those devices are largely now immune to phone interaction or procedures have been established to limit their interaction. The use of cell phones near people with implanted neural stimulators has not been studied. This research was initiated to investigate electromagnetic interaction between current cell phone technology and specific models of Cyberonics neural stimulators. Out of 1080 test runs conducted for this study, no interactions were observed, and it was concluded that the phone technologies examined in this study did not adversely affect the Cyberonics NeuroStar (Model 102) NeuroCybernetic Prosthesis (NCP) System. This article provides details on the experimental procedure that was used, which can also be used to test other neural stimulators and test technologies, and the results obtained. 相似文献
76.
Kobori A Murase T Suda H Saito I Nakatani K 《Bioorganic & medicinal chemistry letters》2004,14(13):3431-3433
We have demonstrated that aromatic heterocycles having hydrogen-bonding surfaces complementary to those of nucleotide bases are effective molecular elements for the binding to single nucleotide bulges and base mismatches. We here report that a new molecule, 2-ureidoquinoline having an alignment of hydrogen-bonding groups in the order of acceptor-donor-donor stabilizes single cytosine and thymine bulges in duplex DNAs. Furthermore, a dimeric form of 2-ureidoquinoline stabilizes cytosine-cytosine and cytosine-thymine mismatches. 相似文献
77.
The influence of sex of broilers and dietary phosphorus (P) level on energy utilization and apparent ileal digestibility of N, P and phytate-P were investigated. The AME(N) was determined using 3- and 6-week old broilers, while the apparent ileal digestibility were determined only with 6-week old birds. Sex of broilers had no effect on the AME(N) values determined during week 3. During week 6, the AME(N) values for male broilers were higher (P < 0.01) than those for the females. An interaction (P < 0.05) between sex and dietary P level was also observed. AME(N) values determined with male broilers were lower in the adequate-P diet compared to those in the low-P diet, whereas no effect of P level was observed in females. Female broilers tended (P < 0.10) to have a higher ileal N digestibility than the males, but a significant (P < 0.01) sex x P level interaction was observed. Males receiving the adequate-P diet had a lower N digestibility than those receiving the low-P diet, whereas the opposite was true in the females. Ileal phytate P degradation in males was higher than in females (0.282 vs. 0.234), but the differences were not significant. Increasing dietary P level increased ileal P digestibility in both the males and females, but the improvements were greater in the females, as indicated by a significant sex x P level interaction. 相似文献
78.
Overexpression of CNP in chondrocytes rescues achondroplasia through a MAPK-dependent pathway 总被引:17,自引:0,他引:17
Yasoda A Komatsu Y Chusho H Miyazawa T Ozasa A Miura M Kurihara T Rogi T Tanaka S Suda M Tamura N Ogawa Y Nakao K 《Nature medicine》2004,10(1):80-86
Achondroplasia is the most common genetic form of human dwarfism, for which there is presently no effective therapy. C-type natriuretic peptide (CNP) is a newly identified molecule that regulates endochondral bone growth through GC-B, a subtype of particulate guanylyl cyclase. Here we show that targeted overexpression of CNP in chondrocytes counteracts dwarfism in a mouse model of achondroplasia with activated fibroblast growth factor receptor 3 (FGFR-3) in the cartilage. CNP prevented the shortening of achondroplastic bones by correcting the decreased extracellular matrix synthesis in the growth plate through inhibition of the MAPK pathway of FGF signaling. CNP had no effect on the STAT-1 pathway of FGF signaling that mediates the decreased proliferation and the delayed differentiation of achondroplastic chondrocytes. These results demonstrate that activation of the CNP-GC-B system in endochondral bone formation constitutes a new therapeutic strategy for human achondroplasia. 相似文献
79.
The genus Reynoutria is represented by four taxa in the Czech Republic: Reynoutria japonica var. japonica, R. japonica var. compacta, R. sachalinensis and R. xbohemica. By using flow cytometry, cytological variability within the genus is described based on 257 Reynoutria samples. The varieties of R. japonica are cytologically uniform, var. japonica is exclusively octoploid (2n = 8x = 88) and var. compacta occurs only as a tetraploid (2n = 4x = 44), but R. sachalinensis and R. xbohemica exhibit some variation in chromosome numbers. Reynoutria sachalinensis is predominantly tetraploid (2n = 4 x = 44), but also occurs occasionally as hexaploid and octoploid cytotypes. The most common ploidy level in R. xbohemica is hexaploid (2n = 6x = 66), but tetraploid and octoploid clones were also found. The four taxa occurring in the Czech Republic are described briefly and the possible origins of the cytotypes discussed. 相似文献
80.
Osteogenic differentiation of the mesenchymal progenitor cells, Kusa is suppressed by Notch signaling 总被引:6,自引:0,他引:6
Shindo K Kawashima N Sakamoto K Yamaguchi A Umezawa A Takagi M Katsube K Suda H 《Experimental cell research》2003,290(2):370-380
Notch receptor plays a crucial role in proliferation and differentiation of many cell types. To elucidate the function of Notch signaling in osteogenesis, we transfected the constitutively active Notch1 (Notch intracellular domain, NICD) into two different osteoblastic mesenchymal cell lines, KusaA and KusaO, and examined the changes of their osteogenic potentials. In NICD stable transformants (KusaA(NICD) and KusaO(NICD)), osteogenic properties including alkaline phosphatase activity, expression of osteocalcin and type I collagen, and in vitro calcification were suppressed. Transient transfection of NICD attenuated the promoter activities of Cbfa1 and Ose2 element. KusaA was capable of forming trabecular bone-like tissues when injected into mouse abdomen, but this in vivo bone forming activity was significantly suppressed in KusaA(NICD). Osteoclasts were induced in the KusaA-derived bone-like tissues, but lacked in the KusaA(NICD)-derived tissues. These results suggest that Notch signaling suppresses the osteoblastic differentiation of mesenchymal progenitor cells. 相似文献