全文获取类型
收费全文 | 8724篇 |
免费 | 826篇 |
国内免费 | 93篇 |
出版年
2022年 | 123篇 |
2021年 | 182篇 |
2020年 | 108篇 |
2019年 | 136篇 |
2018年 | 149篇 |
2017年 | 138篇 |
2016年 | 248篇 |
2015年 | 446篇 |
2014年 | 426篇 |
2013年 | 524篇 |
2012年 | 682篇 |
2011年 | 626篇 |
2010年 | 381篇 |
2009年 | 345篇 |
2008年 | 462篇 |
2007年 | 416篇 |
2006年 | 428篇 |
2005年 | 373篇 |
2004年 | 328篇 |
2003年 | 306篇 |
2002年 | 254篇 |
2001年 | 236篇 |
2000年 | 229篇 |
1999年 | 183篇 |
1998年 | 81篇 |
1997年 | 58篇 |
1996年 | 69篇 |
1995年 | 57篇 |
1994年 | 46篇 |
1993年 | 59篇 |
1992年 | 124篇 |
1991年 | 95篇 |
1990年 | 100篇 |
1989年 | 108篇 |
1988年 | 77篇 |
1987年 | 83篇 |
1986年 | 88篇 |
1985年 | 90篇 |
1984年 | 61篇 |
1983年 | 62篇 |
1982年 | 50篇 |
1981年 | 49篇 |
1980年 | 46篇 |
1979年 | 76篇 |
1978年 | 61篇 |
1977年 | 45篇 |
1976年 | 47篇 |
1975年 | 36篇 |
1974年 | 43篇 |
1973年 | 41篇 |
排序方式: 共有9643条查询结果,搜索用时 15 毫秒
991.
Identification of ciliary and ciliopathy genes in Caenorhabditis elegans through comparative genomics 总被引:2,自引:0,他引:2
992.
993.
Mycoplasma arthritidis mitogen (MAM) is a superantigen secreted by M. arthritidis, an agent of murine arthritis and toxicity. We previously demonstrated that C3H mouse sub-strains differing in expression of Toll-like receptor 4 (TLR4), differed in immune reactivity to MAM due to differential engagement of TLR2 and TLR4. Here we examine the role of B7 co-stimulatory molecules in immune outcome and disease manifestations resulting from these different MAM/TLR2 and MAM/TLR4 interactions. Injections of MAM into C3H/HeJ mice upregulated expression of B7-1 but not B7-2 on peritoneal adherent cells, whereas B7-1 expression was lower on cells from C3H/HeSnJ mice. Anti-B7-1 antibody but not anti-B7-2, injected in vivo, changed the type 1 cytokines in MAM-injected C3H/HeJ mice to a type 2 cytokines and, conversely, the type 2 response in C3H/HeSnJ mice injected with anti-B7-1 shifted to a type 1 pattern. Whereas anti-B7-2 exerted no effect on disease in either mouse strain, anti-B7-1 significantly delayed the lethal toxicity of M. arthritidis in C3H/HeJ mice but enhanced arthritis in C3H/HeSnJ mice. Thus, TLR-mediated regulation of B7-1 results in diverse cytokine profiles in C3H sub-strains, and that the interaction of MAM with different TLR(s) may differentially affect cytokine responses and ultimately, M. arthritidis disease. 相似文献
994.
Plant cells do not have centrioles and their mitosis is frequently likened to the chromosome-based mechanism seen in acentriolar animal cells. However, this is a false analogy. Although plants can use this mechanism, they generally divide by a method that uses bipolar mitotic caps, which is more similar to the canonical centrosome-based method of animals. 相似文献
995.
Cheng Du Baosheng Ge Zhongfeng Liu Kai Fu Wing C Chan Timothy W McKeithan 《BMC biotechnology》2006,6(1):28-11
Background
The use of small interfering RNAs (siRNAs) to silence target gene expression has greatly facilitated mammalian genetic analysis by generating loss-of-function mutants. In recent years, high-throughput, genome-wide screening of siRNA libraries has emerged as a viable approach. Two different methods have been used to generate short hairpin RNA (shRNA) libraries; one is to use chemically synthesized oligonucleotides, and the other is to convert complementary DNAs (cDNAs) into shRNA cassettes enzymatically. The high cost of chemical synthesis and the low efficiency of the enzymatic approach have hampered the widespread use of screening with shRNA libraries. 相似文献996.
997.
998.
999.
1000.
Chan L Stefanac T Turcotte N Hu Z Chen Y Bédard J May S Jin H 《Bioorganic & medicinal chemistry letters》2000,10(13):1477-1480
Following the identification of first pass metabolism issues with our recently described anti-HCMV compounds, the naphthyridines and isoquinolines, we have designed a class of novel metabolically stable and orally bioavailable anti-HCMV agents, the dihydroisoquinolines. 相似文献