全文获取类型
收费全文 | 2255篇 |
免费 | 126篇 |
国内免费 | 1篇 |
专业分类
2382篇 |
出版年
2022年 | 11篇 |
2021年 | 20篇 |
2020年 | 14篇 |
2019年 | 16篇 |
2018年 | 24篇 |
2017年 | 24篇 |
2016年 | 44篇 |
2015年 | 60篇 |
2014年 | 73篇 |
2013年 | 150篇 |
2012年 | 121篇 |
2011年 | 108篇 |
2010年 | 82篇 |
2009年 | 90篇 |
2008年 | 107篇 |
2007年 | 129篇 |
2006年 | 120篇 |
2005年 | 169篇 |
2004年 | 150篇 |
2003年 | 163篇 |
2002年 | 154篇 |
2001年 | 27篇 |
2000年 | 26篇 |
1999年 | 23篇 |
1998年 | 37篇 |
1997年 | 20篇 |
1996年 | 16篇 |
1995年 | 25篇 |
1994年 | 30篇 |
1993年 | 17篇 |
1992年 | 27篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 24篇 |
1988年 | 18篇 |
1987年 | 24篇 |
1986年 | 19篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1983年 | 21篇 |
1982年 | 19篇 |
1981年 | 15篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1975年 | 7篇 |
1974年 | 10篇 |
1973年 | 11篇 |
1968年 | 12篇 |
排序方式: 共有2382条查询结果,搜索用时 15 毫秒
81.
Shigeru Kitanishi Toshiaki Yamamoto Hiromi Ishii Yuko Yamaguchi Toru Kobayashi 《Ichthyological Research》2017,64(1):111-115
To evaluate the influences of spatial scale on dispersal, the dispersal patterns of masu salmon Oncorhynchus masou masou were investigated at among-river (ca. <43 km) and within-river levels in mid-western Hokkaido, Japan. A genetic differentiation (F ST) and assignment test showed that among-river dispersal was much less common (2.9 % of 339 individuals) than within-river dispersal (7.4 % of 190 individuals). We also found that there was no bias in dispersal at the among-river level, while anadromous males were more likely to disperse at the within-river level, suggesting that the dispersal patterns may be scale dependent. 相似文献
82.
George Ohta Masato Kobayshi Tokuma Yanai Hiroki Sakai Masashi Yuki Toshiaki Masegi 《Experimental Animals》2008,57(4):397-400
A 2.5 year-old female ferret had a stiff palpable mass arising from the dorsal surface of the thoracic (T) to lumbar (L) vertebrae with paralysis of the hind limbs. By myelography the dorsal and ventral lines of contrast were not observed in the area forwarded of L3. Grossly, the tumor encircled the dorsal vertebrae. Microscopically, tumor cells were proliferated intimately and were attached to the vertebrae surface involving surrounding fatty and connective tissues. The tumor consisted of fibroblastic cells with prominent cellular atypia. The bromodeoxyuridine (BrdU) labeling index to examine cellular kinetics was high (11.8%). Based on macro and micropathological features, the present tumor was diagnosed as periosteal fibrosarcoma arising from perivertebral connective tissue. 相似文献
83.
Takahashi K Yamaguchi S Shimoyama T Seki H Miyokawa K Katsuta H Tanaka T Yoshimoto K Ohno H Nagamatsu S Ishida H 《American journal of physiology. Endocrinology and metabolism》2008,294(5):E898-E909
Obese conditions increase the expression of adipocytokine monocyte chemoattractant protein-1 (MCP-1) in adipose tissue as well as MCP-1 plasma levels. To investigate the mechanism behind increased MCP-1, we used a model in which 3T3-L1 adipocytes were artificially hypertrophied by preloading with palmitate in vitro. As observed in obesity, under our model conditions, palmitate-preloaded cells showed significantly increased oxidative stress and increased MCP-1 expression relative to control cells. This increased MCP-1 expression was enhanced by adding exogenous tumor necrosis factor-alpha (TNF-alpha; 17.8-fold vs. control cells, P < 0.01) rather than interleukin-1beta (IL-1beta; 2.6-fold vs. control cells, P < 0.01). However, endogenous TNF-alpha and IL-1beta release was not affected in hypertrophied cells, suggesting that these endogenous cytokines do not mediate hypertrophy-induced increase in MCP-1. MCP-1 secretion from hypertrophied cells was significantly decreased by treatment with antioxidant N-acetyl-cysteine, JNK inhibitors SP600125 and JIP-1 peptide, and IkappaB phosphorylation inhibitors BAY 11-7085 and BMS-345541 (P < 0.01). MCP-1 secretion was not affected by peroxisome proliferator-activated receptor-gamma (PPARgamma) antagonists assayed. Adiponectin, another adipocytokine studied in parallel, also showed increased release in hypertrophy relative to control cells. But in contrast to MCP-1, adiponectin release was significantly suppressed by both exogenous TNF-alpha and IL-1beta as well as by PPARgamma antagonists bisphenol A diglycidyl ether and T0070907 (P < 0.01). JNK inhibitors and IkappaB phosphorylation inhibitors showed no significant effect on adiponectin. We conclude that adipocyte hypertrophy through palmitate loading causes oxidative stress, which in turn increases MCP-1 expression and secretion through JNK and IkappaB signaling. In contrast, the parallel increase in adiponectin expression appears to be related to the PPARgamma ligand properties of palmitate. 相似文献
84.
85.
86.
Jun Kojima Jun Araya Hiromichi Hara Saburo Ito Naoki Takasaka Kenji Kobayashi Satoko Fujii Chikako Tsurushige Takanori Numata Takeo Ishikawa Kenichiro Shimizu Makoto Kawaishi Keisuke Saito Noriki Kamiya Jun Hirano Makoto Odaka Toshiaki Morikawa Hiroshi Hano Satoko Arai Toru Miyazaki Yumi Kaneko Katsutoshi Nakayama Kazuyoshi Kuwano 《Respiratory research》2013,14(1):30
Background
Marked accumulation of alveolar macrophages (AM) conferred by apoptosis resistance has been implicated in pathogenesis of chronic obstructive pulmonary disease (COPD). Apoptosis inhibitor of macrophage (AIM), has been shown to be produced by mature tissue macrophages and AIM demonstrates anti-apoptotic property against multiple apoptosis-inducing stimuli. Accordingly, we attempt to determine if AIM is expressed in AM and whether AIM is involved in the regulation of apoptosis in the setting of cigarette smoke extract (CSE) exposure.Methods
Immunohistochemical evaluations of AIM were performed. Immunostaining was assessed by counting total and positively staining AM numbers in each case (n = 5 in control, n = 5 in non-COPD smoker, n = 5 in COPD). AM were isolated from bronchoalveolar lavage fluid (BALF). The changes of AIM expression levels in response to CSE exposure in AM were evaluated. Knock-down of anti-apoptotic Bcl-xL was mediated by siRNA transfection. U937 monocyte-macrophage cell line was used to explore the anti-apoptotic properties of AIM.Results
The numbers of AM and AIM-positive AM were significantly increased in COPD lungs. AIM expression was demonstrated at both mRNA and protein levels in isolated AM, which was enhanced in response to CSE exposure. AIM significantly increased Bcl-xL expression levels in AM and Bcl-xL was involved in a part of anti-apoptotic mechanisms of AIM in U937 cells in the setting of CSE exposure.Conclusions
These results suggest that AIM expression in association with cigarette smoking may be involved in accumulation of AM in COPD. 相似文献87.
Yuriko Osakabe Naoko Arinaga Taishi Umezawa Shogo Katsura Keita Nagamachi Hidenori Tanaka Haruka Ohiraki Kohji Yamada So-Uk Seo Mitsuru Abo Etsuro Yoshimura Kazuo Shinozaki Kazuko Yamaguchi-Shinozaki 《The Plant cell》2013,25(2):609-624
Osmotic adjustment plays a fundamental role in water stress responses and growth in plants; however, the molecular mechanisms governing this process are not fully understood. Here, we demonstrated that the KUP potassium transporter family plays important roles in this process, under the control of abscisic acid (ABA) and auxin. We generated Arabidopsis thaliana multiple mutants for K+ uptake transporter 6 (KUP6), KUP8, KUP2/SHORT HYPOCOTYL3, and an ABA-responsive potassium efflux channel, guard cell outward rectifying K+ channel (GORK). The triple mutants, kup268 and kup68 gork, exhibited enhanced cell expansion, suggesting that these KUPs negatively regulate turgor-dependent growth. Potassium uptake experiments using 86radioactive rubidium ion (86Rb+) in the mutants indicated that these KUPs might be involved in potassium efflux in Arabidopsis roots. The mutants showed increased auxin responses and decreased sensitivity to an auxin inhibitor (1-N-naphthylphthalamic acid) and ABA in lateral root growth. During water deficit stress, kup68 gork impaired ABA-mediated stomatal closing, and kup268 and kup68 gork decreased survival of drought stress. The protein kinase SNF1-related protein kinases 2E (SRK2E), a key component of ABA signaling, interacted with and phosphorylated KUP6, suggesting that KUP functions are regulated directly via an ABA signaling complex. We propose that the KUP6 subfamily transporters act as key factors in osmotic adjustment by balancing potassium homeostasis in cell growth and drought stress responses. 相似文献
88.
Kanbe Y Kim MH Nishimoto M Ohtake Y Yoneya T Ohizumi I Tsunenari T Taniguchi K Kaiho S Nabuchi Y Araya H Kawata S Morikawa K Jo JC Kwon HA Lim HS Kim HY 《Bioorganic & medicinal chemistry letters》2006,16(18):4959-4964
In order to develop orally active pure antiestrogens, we incorporated the carboxy-containing side chains into the 7alpha-position of the steroid scaffold and found that 17-keto derivative CH4893237 (12b) functioned as a pure antiestrogen with its oral activity much superior to clinically used pure antiestrogen, ICI182,780. Results from the pharmacokinetic evaluation indicated that the potent antiestrogen activity at oral dosing in mice attributed to both improved absorption from the intestinal wall and metabolic stability in liver. 相似文献
89.
90.
Toru Ishikawa Satoshi Abe Asami Hoshii Yumi Yamada Akihiko Iiduka Takeo Nemoto Keiko Takeda Toshiaki Yoshida 《PloS one》2016,11(1)