全文获取类型
收费全文 | 2292篇 |
免费 | 159篇 |
专业分类
2451篇 |
出版年
2023年 | 12篇 |
2022年 | 13篇 |
2021年 | 29篇 |
2020年 | 13篇 |
2019年 | 31篇 |
2018年 | 30篇 |
2017年 | 31篇 |
2016年 | 37篇 |
2015年 | 72篇 |
2014年 | 55篇 |
2013年 | 121篇 |
2012年 | 119篇 |
2011年 | 119篇 |
2010年 | 80篇 |
2009年 | 91篇 |
2008年 | 117篇 |
2007年 | 95篇 |
2006年 | 112篇 |
2005年 | 128篇 |
2004年 | 116篇 |
2003年 | 99篇 |
2002年 | 92篇 |
2001年 | 76篇 |
2000年 | 82篇 |
1999年 | 78篇 |
1998年 | 25篇 |
1997年 | 32篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 19篇 |
1993年 | 24篇 |
1992年 | 47篇 |
1991年 | 49篇 |
1990年 | 29篇 |
1989年 | 23篇 |
1988年 | 43篇 |
1987年 | 23篇 |
1986年 | 22篇 |
1985年 | 33篇 |
1984年 | 31篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1975年 | 13篇 |
1974年 | 10篇 |
1972年 | 12篇 |
1969年 | 9篇 |
1968年 | 11篇 |
排序方式: 共有2451条查询结果,搜索用时 15 毫秒
21.
K Yamamoto K Itoh S Yoshida K Saito Y Sakamoto A Matsuda T Saito T Kuzuya 《Endocrinologia japonica》1979,26(2):255-261
Using B-mode ultrasonography, an attempt was made to measure the volume of extraocular muscles and retrobulbar fat in 31 patients (62 orbits) with Graves' disease. None of the patients had exophthalmometric measurements greater than 21 mm or had eye symptoms. The mean value of muscle volume of Graves' patients was significantly larger than that of normal controls (6.48 +/- 2.70 cm3 and 3.25 +/- 1.30 cm3, respectively, p less than 0.001). All of the patients had extraocular muscle swelling, although 2 of them had no extraocular muscle change for their unilateral eye. The extraocular muscle volume increased as the degree of the proptosis increased. The fat volume tended to increase in parallel with the degree of the proptosis. In the Graves' group with obvious proptosis (Hertel reading: 19--21 mm), the fat volume increased more significantly than in any other group. The ratio of extraocular muscle volume to retrobulbar fat volume was significantly higher in Graves' disease, but it did not increase as the degree of the proptosis increased. A significant correlation between proptosis and muscle volume plus fat volume was observed. No significant difference of the extraocular muscle volume was observed between the patients untreated and treated with antithyroid drugs. The data show a uniform enlargement of the extraocular muscles in Graves' disease and also suggest an involvement of increased retrobulbar fat volume in a group of obvious exophthalmos. The degree of the proptosis is in aclose proportion ot the quantitative change of the orbital soft tissue. 相似文献
22.
Yoshikazu Arai Jun Ohgane Shuh‐hei Fujishiro Kazuaki Nakano Hitomi Matsunari Masahito Watanabe Kazuhiro Umeyama Dai Azuma Naomi Uchida Nozomu Sakamoto Tomohiro Makino Shintaro Yagi Kunio Shiota Yutaka Hanazono Hiroshi Nagashima 《Genesis (New York, N.Y. : 2000)》2013,51(11):763-776
Porcine induced pluripotent stem cells (iPSCs) provide useful information for translational research. The quality of iPSCs can be assessed by their ability to differentiate into various cell types after chimera formation. However, analysis of chimera formation in pigs is a labor‐intensive and costly process, necessitating a simple evaluation method for porcine iPSCs. Our previous study identified mouse embryonic stem cell (ESC)‐specific hypomethylated loci (EShypo‐T‐DMRs), and, in this study, 36 genes selected from these were used to evaluate porcine iPSC lines. Based on the methylation profiles of the 36 genes, the iPSC line, Porco Rosso‐4, was found closest to mouse pluripotent stem cells among 5 porcine iPSCs. Moreover, Porco Rosso‐4 more efficiently contributed to the inner cell mass (ICM) of blastocysts than the iPSC line showing the lowest reprogramming of the 36 genes (Porco Rosso‐622‐14), indicating that the DNA methylation profile correlates with efficiency of ICM contribution. Furthermore, factors known to enhance iPSC quality (serum‐free medium with PD0325901 and CHIR99021) improved the methylation status at the 36 genes. Thus, the DNA methylation profile of these 36 genes is a viable index for evaluation of porcine iPSCs. genesis 51:763–776. © 2013 Wiley Periodicals, Inc. 相似文献
23.
X-ray crystallographic and biochemical characterization of the inhibitory action of an imidazole-dioxolane compound on heme oxygenase 总被引:1,自引:0,他引:1
Sugishima M Higashimoto Y Oishi T Takahashi H Sakamoto H Noguchi M Fukuyama K 《Biochemistry》2007,46(7):1860-1867
Heme oxygenase (HO) catalyzes the regiospecific cleavage of the porphyrin ring of heme using reducing equivalents and O2 to produce biliverdin, iron, and CO. Because CO has a cytoprotective effect through the p38-MAPK pathway, HO is a potential therapeutic target in cancer. In fact, inhibition of the HO isoform HO-1 reduces Kaposi sarcoma tumor growth. Imidazole-dioxolane compounds have recently attracted attention because they have been reported to specifically inhibit HO-1, but not HO-2, unlike Cr-containing protoporphyrin IX, a classical inhibitor of HO, that inhibits not only both HO isoforms but also other hemoproteins. The inhibitory mechanism of imidazole-dioxolane compounds, however, has not yet been characterized. Here, we determine the crystal structure of the ternary complex of rat HO-1, heme, and an imidazole-dioxolane compound, 2-[2-(4-chlorophenyl)ethyl]-2-[(1H-imidazol-1-yl)methyl]-1,3-dioxolane. This compound bound on the distal side of the heme iron, where the imidazole and 4-chlorophenyl groups were bound to the heme iron and the hydrophobic cavity in HO, respectively. Binding of the bulky inhibitor in the narrow distal pocket shifted the distal helix to open the distal site and moved both the heme and the proximal helix. Furthermore, the biochemical characterization revealed that the catalytic reactions of both HO-1 and HO-2 were completely stopped after the formation of verdoheme in the presence of the imidazole-dioxolane compound. This result should be mainly due to the lower reactivity of the inhibitor-bound verdoheme with O2 compared to the reactivity of the inhibitor-bound heme with O2. 相似文献
24.
25.
Brusatte SL Sakamoto M Montanari S Harcourt Smith WE 《Journal of evolutionary biology》2012,25(2):365-377
Theropod dinosaurs, an iconic clade of fossil species including Tyrannosaurus and Velociraptor, developed a great diversity of body size, skull form and feeding habits over their 160+ million year evolutionary history. Here, we utilize geometric morphometrics to study broad patterns in theropod skull shape variation and compare the distribution of taxa in cranial morphospace (form) to both phylogeny and quantitative metrics of biting behaviour (function). We find that theropod skulls primarily differ in relative anteroposterior length and snout depth and to a lesser extent in orbit size and depth of the cheek region, and oviraptorosaurs deviate most strongly from the "typical" and ancestral theropod morphologies. Noncarnivorous taxa generally fall out in distinct regions of morphospace and exhibit greater overall disparity than carnivorous taxa, whereas large-bodied carnivores independently converge on the same region of morphospace. The distribution of taxa in morphospace is strongly correlated with phylogeny but only weakly correlated with functional biting behaviour. These results imply that phylogeny, not biting function, was the major determinant of theropod skull shape. 相似文献
26.
27.
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
28.
Yuki Sakamoto Jun Yamazaki Takayuki Yamada Jun Yokoyama Yuki Ogura‐Tsujita Masayuki Maki 《Plant Species Biology》2017,32(1):81-86
The diversity of mycorrhizal fungi among four Japanese Cephalanthera (Orchidaceae) species was examined at a total of seven sites, based on sequence variation in nuclear ribosomal DNA. This is the first report to detect mycorrhizal fungi in C. subaphylla. Two patterns of mycorrhizal associations were confirmed from our results. C. falcata has lower fungal specificity, associating with Russulaceae, Sebacinales and Thelephoraceae. By contrast, the three Cephalanthera species C. erecta, C. subaphylla, and C. longifolia were associated mainly with Thelephoraceae fungi. There is no large difference found in mycobionts between green and albino individuals of C. falcata and no distinct preference of Japanese Cephalanthera species for a specific fungal group of Thelephoraceae. 相似文献
29.
30.
CCL3 is a proinflammatory chemokine that mediates many of the cellular changes occurring in pulmonary disease. Here, CCL3−/− mice were used to investigate the role of this chemokine during respiratory herpesvirus infection. Compared to wild-type mice, CCL3−/− mice infected with the alphaherpesvirus equine herpesvirus 1 (EHV-1) displayed reduced body weight loss but had higher pulmonary viral loads. Lungs from infected CCL3−/− mice suffered a milder interstitial pneumonia, and fewer immune cells were recovered from the pulmonary airways after infection. We could also demonstrate that herpesvirus-encoded chemokine-binding glycoprotein G (gG) was capable of inhibiting the chemotactic functions of CCL3. This CCL3-mediated chemotaxis, however, was restored in the presence of gG-specific antibodies, which puts into question the advertised use of gG deletion mutants as marker vaccines. In summary, we concluded that CCL3 is a major player in controlling herpesvirus replication in the target organ, the lung, and does so by evoking a strong inflammatory response. The immunomodulatory activity of CCL3 is balanced by the expression of viral gG, whose chemokine-binding activity is mitigated in secondary infections by the production of anti-gG antibodies. 相似文献