全文获取类型
收费全文 | 6258篇 |
免费 | 654篇 |
国内免费 | 85篇 |
出版年
2022年 | 28篇 |
2021年 | 122篇 |
2020年 | 85篇 |
2019年 | 89篇 |
2018年 | 78篇 |
2017年 | 107篇 |
2016年 | 126篇 |
2015年 | 237篇 |
2014年 | 291篇 |
2013年 | 344篇 |
2012年 | 444篇 |
2011年 | 443篇 |
2010年 | 278篇 |
2009年 | 232篇 |
2008年 | 329篇 |
2007年 | 377篇 |
2006年 | 314篇 |
2005年 | 329篇 |
2004年 | 273篇 |
2003年 | 261篇 |
2002年 | 251篇 |
2001年 | 132篇 |
2000年 | 109篇 |
1999年 | 103篇 |
1998年 | 83篇 |
1997年 | 57篇 |
1996年 | 52篇 |
1995年 | 60篇 |
1994年 | 71篇 |
1993年 | 48篇 |
1992年 | 68篇 |
1991年 | 67篇 |
1990年 | 75篇 |
1989年 | 85篇 |
1988年 | 63篇 |
1987年 | 76篇 |
1986年 | 56篇 |
1985年 | 44篇 |
1984年 | 57篇 |
1983年 | 26篇 |
1982年 | 41篇 |
1981年 | 32篇 |
1980年 | 26篇 |
1979年 | 42篇 |
1978年 | 37篇 |
1976年 | 43篇 |
1974年 | 31篇 |
1972年 | 35篇 |
1970年 | 26篇 |
1969年 | 25篇 |
排序方式: 共有6997条查询结果,搜索用时 15 毫秒
1.
2.
Complement components and terminal complement complex in oesophageal smooth muscle of patients with achalasia. 总被引:3,自引:0,他引:3
Wulf B Storch Volker F Eckardt Theo Junginger 《Cellular and molecular biology, including cyto-enzymology》2002,48(3):247-252
This study investigates whether patients with achalasia exhibit autoimmune reactions with subsequent complement activation within oesophageal smooth muscle, vessels and neurones. Oesophageal muscular biopsies from 8 patients undergoing surgery for achalasia and from 6 patients operated for oesophageal cancer were investigated by immunofluorescence for the presence of the complement components C1q, C4, C3c, C3d, C9 and the C9 neoantigen of the terminal C5b-C9 complement complex. Tissues were also investigated for the expression of immunoglobulins (G,A,M) and of the antigens of rubella and varicella zoster viruses. In addition, sera of both patient groups were tested for the presence of autoantibodies against Auerbach's plexus. The terminal complement complex C5b-C9 was found within muscle cells from all patients with achalasia but in only one specimen from a patient with cancer. Two patients with achalasia also exhibited the terminal complement complex as well as IgM within ganglion cells. Muscle cells stained positive for the complement component C9 in all five patients with achalasia in whom this test was performed but in none of the control tissues. In addition, sera from four patients with achalasia contained antibodies against Auerbach's plexus. Studies for the complement components C1q, C4, C3c and for antigens of rubella and varicella zoster viruses revealed negative results in all patients and controls. The results of this study suggest that a complement activation is involved in the autoimmune pathogenesis of achalasia. However, the triggering mechanism of this phenomenon remains to be determined. 相似文献
3.
Yveta Lhotáková Luká? Plí?til Alena Morávková Pavel Kubát Kamil Lang Jitka Forstová Ji?í Mosinger 《PloS one》2012,7(11)
Novel biomaterials based on hydrophilic polycaprolactone and polyurethane (Tecophilic®) nanofibers with an encapsulated 5,10,5,20-tetraphenylporphyrin photosensitizer were prepared by electrospinning. The doped nanofiber textiles efficiently photo-generate O2(1Δg), which oxidize external chemical and biological substrates/targets. Strong photo-virucidal effects toward non-enveloped polyomaviruses and enveloped baculoviruses were observed on the surface of these textiles. The photo-virucidal effect was confirmed by a decrease in virus infectivity. In contrast, no virucidal effect was detected in the absence of light and/or the encapsulated photosensitizer. 相似文献
4.
Albumin in urine is selectively adsorbed on an immunoadsorber (human serum albumin-specific antibodies coupled covalently with a silica stationary phase) and after elution with 0.1% HCl is quantitatively determined by reversed-phase chromatography with detection of native fluorescence. The optimization of sample preparation and characteristics of the method such as recovery, linearity, reproducibility, detection limit, and selectivity are discussed. 相似文献
5.
6.
7.
Summary Granules isolated from the blue-green alga Anabaena cylindrica and composed of copolymers of arginine and aspartic acid have the electron microscopic aspects of structured granules and the solubility and certain of the staining properties of cyanophycin granules. Material which accumulates at the poles of heterocysts may have a similar composition. 相似文献
8.
9.
In vivo neutralization of TNF-alpha promotes humoral autoimmunity by preventing the induction of CTL. 总被引:3,自引:0,他引:3
C S Via A Shustov V Rus T Lang P Nguyen F D Finkelman 《Journal of immunology (Baltimore, Md. : 1950)》2001,167(12):6821-6826
Neutralization of TNF-alpha in humans with rheumatoid arthritis or Crohn's disease has been associated with the development of humoral autoimmunity. To determine the effect of TNF-alpha neutralization on cell-mediated and humoral-mediated responses, we administered anti-TNF-alpha mAb to mice undergoing acute graft-vs-host disease (GVHD) using the parent-into-F(1) model. In vivo neutralization of TNF-alpha blocked the lymphocytopenic features characteristic of acute GVHD and induced a lupus-like chronic GVHD phenotype (lymphoproliferation and autoantibody production). These effects resulted from complete inhibition of detectable antihost CTL activity and required the presence of anti-TNF-alpha mAb for the first 4 days after parental cell transfer, indicating that TNF-alpha plays a critical role in the induction of CTL. Moreover, an in vivo blockade of TNF-alpha preferentially inhibited the production of IFN-gamma and blocked IFN-gamma-dependent up-regulation of Fas; however, cytokines such as IL-10, IL-6, or IL-4 were not inhibited. These results suggest that a therapeutic TNF-alpha blockade may promote humoral autoimmunity by selectively inhibiting the induction of a CTL response that would normally suppress autoreactive B cells. 相似文献
10.
为明确昆虫抗冻蛋白基因转入甘薯(Ipomoea batatas)后是否能提升其抗冻能力,进而为培育甘薯抗冻育种材料奠定基础,将黄粉虫(Tenebrio molitor)抗冻蛋白基因TmAFP导入植物基因表达质粒,经农杆菌介导的遗传转化获得抗冻甘薯新材料。以甘薯品种Huachano为受体材料建立甘薯植株高效再生体系,并采用不同成分的体细胞胚成熟培养基培养胚性悬浮细胞。胚性愈伤组织对除草剂的敏感性测试结果表明,转基因阳性植株筛选的最适培养基为MS+0.2 mg·L–12,4-D+0.8 mg·L^–1 GAP+100 mg·L^–1 Carb。将表达质粒分别转化Huachano后共获得7个胚性愈伤团并最终获得42株再生抗性植株,其中转pSUIBEV3-AFP有23个株系,转pCAMBIA-AFP有19个株系,经PCR、Southern杂交和RT-PCR检测后证实TmAFP基因已整合至甘薯基因组中并获得表达。将转基因甘薯及对照植株在–1℃下处理15小时后转移至室温,结果表明,转基因甘薯植株的抗冻能力显著提升。 相似文献