全文获取类型
收费全文 | 10374篇 |
免费 | 738篇 |
国内免费 | 7篇 |
出版年
2023年 | 34篇 |
2022年 | 18篇 |
2021年 | 164篇 |
2020年 | 149篇 |
2019年 | 177篇 |
2018年 | 307篇 |
2017年 | 248篇 |
2016年 | 398篇 |
2015年 | 633篇 |
2014年 | 701篇 |
2013年 | 751篇 |
2012年 | 1036篇 |
2011年 | 910篇 |
2010年 | 556篇 |
2009年 | 506篇 |
2008年 | 697篇 |
2007年 | 636篇 |
2006年 | 545篇 |
2005年 | 480篇 |
2004年 | 436篇 |
2003年 | 388篇 |
2002年 | 312篇 |
2001年 | 216篇 |
2000年 | 204篇 |
1999年 | 176篇 |
1998年 | 65篇 |
1997年 | 51篇 |
1996年 | 32篇 |
1995年 | 37篇 |
1994年 | 26篇 |
1993年 | 22篇 |
1992年 | 33篇 |
1991年 | 27篇 |
1990年 | 18篇 |
1989年 | 17篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1974年 | 7篇 |
1969年 | 4篇 |
1967年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The lateral resolution of continuous wave (CW) stimulated emission depletion (STED) microscopy is enhanced about 12% by applying annular‐shaped amplitude modulation to the radially polarized excitation beam. A focused annularly filtered radially polarized excitation beam provides a more condensed point spread function (PSF), which contributes to enhance effective STED resolution of CW STED microscopy. Theoretical analysis shows that the FWHM of the effective PSF on the detection plane is smaller than for conventional CW STED. Simulation shows the donut‐shaped PSF of the depletion beam and confocal optics suppress undesired PSF sidelobes. Imaging experiments agree with the simulated resolution improvement. 相似文献
72.
73.
74.
Woo Seung Son Kyu-Sung Jeong Sang Min Lim Ae Nim Pae 《Bioorganic & medicinal chemistry letters》2019,29(10):1168-1172
Highly effective and safe drugs for the treatment of neuropathic pain are urgently required and it was shown that blocking T-type calcium channels can be a promising strategy for drug development for neuropathic pain. We have developed pyrrolidine-based T-type calcium channel inhibitors by structural hybridization and subsequent assessment of in vitro activities against Cav3.1 and Cav3.2 channels. Profiling of in vitro ADME properties of compounds was also carried out. The representative compound 17h showed comparable in vivo efficacy to gabapentin in the SNL model, which indicates T-type calcium channel inhibitors can be developed as effective therapeutics for neuropathic pain. 相似文献
75.
Jeyun Jo Heegyu Kim Ji Youn Oh Soyeong Kim Yeong Hye Park Hyeonjin Choi Jee-Yeong Jeong Young-Suk Jung Hwayoung Yun 《Bioorganic & medicinal chemistry letters》2019,29(24):126752
Triple-negative breast cancers (TNBCs) account for approximately 15% of breast cancer cases and exhibit an aggressive clinical behavior. In this study, we designed and synthesized two series of 2-anilinopyrimidines based on the structure of our previously reported compound 1 that act as a selective inhibitor of the basal-like TNBC cell line MDA-MB-468. Through the fine-tuning of 1, cyclic and acyclic amines at 4-position of the pyrimidine core were turned out to be crucial for the selectivity. An extensive analysis of structure-activity relationships of the analogs revealed that aminoalkyl groups at the end of the propyl chain are amenable to modification. Among the newly synthesized analogs, compound 38, bearing 4-chloropiperidinyl and cyclohexyl groups, was found to be the most potent and selective, and was about three times more potent and selective than 1 was against the TNBC cells. 相似文献
76.
Woong-Hee Kim Pyeonghwa Jeong Seon-Wook Kim Haaglim Cho Jeong-min Lee Shinae Seo Haihong Shen Youngkeun Ahn Da-Woon Jung Yong-Chul Kim Darren R. Williams 《Bioorganic & medicinal chemistry》2019,27(13):2923-2934
Indirubin-based compounds affect diverse biological processes, such as inflammation and angiogenesis. In this study, we tested a novel indirubin derivative, LDD-1819 (2-((((2Z,3E)-5-hydroxy-5′-nitro-2′-oxo-[2,3′-biindolinylidene]-3-ylidene)amino)oxy)ethan-1-aminium chloride) for two major biological activities: cell plasticity and anti-cancer activity. Biological assays indicated that LDD-1819 induced somatic cell plasticity. LDD-1819 potentiated myoblast reprogramming into osteogenic cells and fibroblast reprogramming into adipogenic cells. Interestingly, in an assay of skeletal muscle dedifferentiation, LDD-1819 induced human muscle cellularization and blocked residual proliferative activity to produce a population of mononuclear refractory cells, which is also observed in the early stages of limb regeneration in urodele amphibians. In cancer cell lines, LDD-1819 treatment inhibited cell invasion and selectively induced apoptosis compared to normal cells. In an animal tumor xenograft model, LDD-1819 reduced human cancer cell metastasis in vivo at doses that did not produce toxicity. Biochemical assays showed that LDD-1819 possessed inhibitory activity against glycogen synthase kinase-3β, which is linked to cell plasticity, and aurora kinase, which regulates carcinogenesis. These results indicate that novel indirubin derivative LDD-1819 is a dual inhibitor of glycogen synthase kinase-3β and aurora A kinase, and has potential for development as an anti-cancer drug or as a reprogramming agent for cell-therapy based approaches to treat degenerative diseases. 相似文献
77.
Meeja Seo Jeong Hwan Kim Bo Yoon Seo Changgyu Park Byeong Ryeol Choi Kwang Ho Kim Chang Woo Ji Jum Rae Cho 《Journal of Asia》2019,22(4):1013-1018
Anastatus orientalis is a solitary endoparasitoid of Lycorma delicatula (Hemiptera: Fulgoridae) eggs. We investigated the development, longevity, fecundity, and sex ratio of A. orientalis on different temperatures to establish the optimal temperature condition for laboratory mass rearing. There were significant differences in its development and longevity between 15 °C and the rest of temperature conditions (20, 25, and 30 °C), among which were no significant differences. The average number of eggs laid by A. orientalis was higher at 20 and 25 °C, but there was no statistically significant difference in its fecundity between the two temperatures. More females emerged at 15 and 20 °C than higher temperatures.Parasitisms of A. orientalis varied with host egg ages and densities. Even in 14 day old eggs of L. delicatula, parasitoids successfully emerged from 92.3% of the parasitized eggs. On the other hand, parasitism was lowest (13.8%) on just before hatching eggs. Parasitism was negatively dependent on host density.Oviposition behavior for A. orientalis primarily occurred at 1400–1600 h, not at 2400–0800 h. The majority of this parasitoid's emergence occurred at 0800–1000 h, largely before noon. These results may be useful for controlling the adequate time for supplying host eggs and release density of this parasitoid as well as for potentially predicting the accurate time for securing parasitoid adults in laboratory mass rearing of A. orientalis. 相似文献
78.
Nguyen Thu Thi Hwang In Yeub Na Jeong Geol Lee Eun Yeol 《Journal of industrial microbiology & biotechnology》2019,46(5):675-685
Journal of Industrial Microbiology & Biotechnology - Propane is the main component of liquefied petroleum gas and is derived from crude oil processing. Methanotrophic bacteria can convert... 相似文献
79.
Kyung Eun Kim Eun Ae Jeong Hyun Joo Shin Jong Youl Lee Eun Bee Choi Hyeong Seok An Kyung-Ah Park Zhen Jin Dong Kun Lee Tamas L. Horvath Gu Seob Roh 《Biochemical and biophysical research communications》2019,508(1):123-129
Hypothalamic inflammation has been known as a contributor to high-fat diet (HFD)-induced insulin resistance and obesity. Myeloid-specific sirtuin 1 (SIRT1) deletion aggravates insulin resistance and hypothalamic inflammation in HFD-fed mice. Neurogranin, a calmodulin-binding protein, is expressed in the hypothalamus. However, the effects of myeloid SIRT1 deletion on hypothalamic neurogranin has not been fully clarified. To investigate the effect of myeloid SIRT1 deletion on food intake and hypothalamic neurogranin expression, mice were fed a HFD for 20 weeks. Myeloid SIRT1 knockout (KO) mice exhibited higher food intake, weight gain, and lower expression of anorexigenic proopiomelanocortin in the arcuate nucleus than WT mice. In particular, KO mice had lower ventromedial hypothalamus (VMH)-specific neurogranin expression. However, SIRT1 deletion reduced HFD-induced hypothalamic neurogranin. Furthermore, hypothalamic phosphorylated AMPK and parvalbumin protein levels were also lower in HFD-fed KO mice than in HFD-fed WT mice. Thus, these findings suggest that myeloid SIRT1 deletion affects food intake through VMH-specific neurogranin-mediated AMPK signaling and hypothalamic inflammation in mice fed a HFD. 相似文献