全文获取类型
收费全文 | 5904篇 |
免费 | 520篇 |
国内免费 | 274篇 |
出版年
2023年 | 32篇 |
2022年 | 135篇 |
2021年 | 259篇 |
2020年 | 177篇 |
2019年 | 199篇 |
2018年 | 215篇 |
2017年 | 147篇 |
2016年 | 199篇 |
2015年 | 330篇 |
2014年 | 400篇 |
2013年 | 396篇 |
2012年 | 494篇 |
2011年 | 426篇 |
2010年 | 286篇 |
2009年 | 272篇 |
2008年 | 341篇 |
2007年 | 277篇 |
2006年 | 228篇 |
2005年 | 201篇 |
2004年 | 161篇 |
2003年 | 182篇 |
2002年 | 170篇 |
2001年 | 102篇 |
2000年 | 91篇 |
1999年 | 74篇 |
1998年 | 53篇 |
1997年 | 49篇 |
1996年 | 53篇 |
1995年 | 52篇 |
1994年 | 41篇 |
1993年 | 44篇 |
1992年 | 40篇 |
1991年 | 40篇 |
1990年 | 39篇 |
1989年 | 31篇 |
1988年 | 20篇 |
1987年 | 31篇 |
1986年 | 34篇 |
1985年 | 22篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 24篇 |
1981年 | 32篇 |
1980年 | 18篇 |
1979年 | 24篇 |
1978年 | 14篇 |
1976年 | 14篇 |
1975年 | 15篇 |
1974年 | 16篇 |
1973年 | 22篇 |
排序方式: 共有6698条查询结果,搜索用时 15 毫秒
141.
Shenghao Hua Tao Feng Lei Yin Qi Wang Xuejun Shao 《Journal of cellular and molecular medicine》2021,25(19):9331-9339
It has been demonstrated that neural precursor cell expressed developmentally downregulated protein (NEDD) plays crucial roles in tumorigenesis and may serve as potential biomarkers in cancer diagnosis and prognosis. However, few studies systematically investigated the expression of NEDD family members in acute myeloid leukaemia (AML). We systemically determined the expression of NEDD family members in AML and determined their clinical significance. We identified that NEDD9 expression was the only member among NEDD family which was significantly increased in AML. NEDD9 overexpression was more frequently classified as FAB-M4/M5 (p = 0.008 and 0.013, respectively), hardly as FAB-M2/M3. Moreover, NEDD9 overexpression was significantly associated with complex karyotype and TP53 mutation. The significant association between NEDD9 overexpression and survival was also observed in whole-cohort AML and non-M3 AML patients. Notably, AML patients with NEDD9 overexpression may benefit from hematopoietic stem cell transplantation (HSCT), whereas those cases without NEDD9 overexpression did not. Finally, a total of 822 mRNAs and 31 microRNAs were found to be differentially expressed between two groups. Among the microRNAs, miR-381 was also identified as a microRNA that could direct target NEDD9. Taken together, our findings demonstrated that NEDD9 overexpression is associated with genetic abnormalities as well as prognosis and might act as a potential biomarker guiding the choice between HSCT and chemotherapy in patients with AML after achieving complete remission. 相似文献
142.
Arunagiri Kuha Deva Magendhra Rao Vittal Rangan Arvinden Deepa Ramasamy Krishna Patel Balaiah Meenakumari Priya Ramanathan Shirley Sundersingh Velusami Sridevi Thangarajan Rajkumar Zdenko Herceg Harsha Gowda Samson Mani 《Journal of cellular and molecular medicine》2021,25(8):3912-3921
Breast cancer is a major cause of cancer-related death in women worldwide. Non-coding RNAs are a potential resource to be used as an early diagnostic biomarker for breast cancer. Circular RNAs are a recently identified group of non-coding RNA with a significant role in disease development with potential utility in diagnosis/prognosis in cancer. In this study, we identified 26 differentially expressed circular RNAs associated with early-stage breast cancer. RNA sequencing and two circRNA detection tools (find_circ and DCC) were used to understand the circRNA expression signature in breast cancer. We identified hsa_circ_0006743 (circJMJD1C) and hsa_circ_0002496 (circAPPBP1) to be significantly up-regulated in early-stage breast cancer tissues. Co-expression analysis identified four pairs of circRNA-miRNA (hsa_circ_0023990 : hsa-miR-548b-3p, hsa_circ_0016601 : hsa_miR-1246, hsa_circ_0001946 : hsa-miR-1299 and hsa_circ_0000117:hsa-miR-502-5p) having potential interaction. The miRNA target prediction and network analysis revealed mRNA possibly regulated by circRNAs. We have thus identified circRNAs of diagnostic implications in breast cancer and also observed circRNA-miRNA interaction which could be involved in breast cancer development. 相似文献
143.
Mao Ting Zhu Mingdong Ahmad Shakeel Ye Guoyou Sheng Zhonghua Hu Shikai Jiao Guiai Xie Lihong Tang Shaoqing Wei Xiangjin Hu Peisong Shao Gaoneng 《Molecular breeding : new strategies in plant improvement》2021,41(10):1-14
Molecular Breeding - The stem color of young mung bean is a very useful tool in germplasm identification. Flowering time and plant height (PH) are known to be strongly correlated with crop adaption... 相似文献
144.
Weiwei Kuang Wenlong Hu Hong Ren Yinhong Shao Bingqian Liu 《Saudi Journal of Biological Sciences》2021,28(5):2739-2746
The current study was undertaken to investigate anticancer activity of coumestrol phytoestrogen against human skin cancer. MTT assay was performed for cell viability assessment and clonogenic assay for cell colony formation assessment. Apoptosis was analysed by Annexin V/FITC staining, AO/EB staining and western blotting assays. Effects on the m-TOR/PI3K/AKT signalling pathway were investigated by western blotting. Results indicated that coumestrol induced significant toxicity in human skin cancer cells in contrast to mouse skin cancer cells. The proliferation rate in normal skin cells remained almost intact. Annexin V-FITC and AO/EB staining assays indicated coumestrol induced cytotoxicity in skin cancer cells is mediated through apoptosis stimulation. The apoptosis in skin cancer cells was mediated through caspase-activation. Cell migration and invasion was inhibited by coumestrol in human skin cancer cells via inhibition of MMP-2 and MMP-9 expressions. Moreover, m-TOR/PI3K/AKT signalling pathway in SKEM-5 cells was blocked by coumestrol. 相似文献
145.
Frigeir Grímsson Silvia Ulrich Mario Coiro Shirley A. Graham Bonnie F. Jacobs Ellen D. Currano Alexandros Xafis Reinhard Zetter 《Ecology and evolution》2021,11(10):5164
Fossil pollen believed to be related to extant Hagenia abyssinica were discovered in the early Miocene (21.73 Ma) Mush Valley paleoflora, Ethiopia, Africa. Both the fossil and extant pollen grains of H. abyssinica were examined with combined light microscopy, scanning electron microscopy, and transmission electron microscopy to compare the pollen and establish their relationships. Based on this, the fossil pollen grains were attributed to Hagenia. The presence of Hagenia in the fossil assemblage raises the questions if its habitat has changed over time, and if the plants are/were wind pollinated. To shed light on these questions, the morphology of extant anthers was also studied, revealing specialized hairs inside the anthers, believed to aid in insect pollination. Pollen and anther morphology are discussed in relation to the age and origin of the genus within a molecular dated phylogenetic framework, the establishment of complex topography in East Africa, other evidence regarding pollination modes, and the palynological record. The evidence presented herein, and compiled from the literature, suggests that Hagenia was an insect‐pollinated lowland rainforest element during the early Miocene of the Mush Valley. The current Afromontane habitat and ambophilous (insect and wind) pollination must have evolved in post‐mid‐Miocene times. 相似文献
146.
147.
Zhao Lv Lan Chen Lingyun Chen Chen Shao Miao Miao Alan Warren 《The Journal of eukaryotic microbiology》2013,60(5):455-466
The live morphology, infraciliature, and morphogenesis of a new oxytrichid ciliate, Notohymena apoaustralis n. sp. collected from a freshwater pond in Qingdao (Tsingtao), China, were studied in vivo and after protargol impregnation. Notohymena apoaustralis n. sp. is characterized as follows: undulating membranes in Notohymena‐pattern; cortical granules yellow‐green, grouped around the marginal cirri and dorsal bristles, and in short irregular rows elsewhere in the cell; single contractile vacuole positioned at anterior 1/3 of the body length; two macronuclear nodules and one micronucleus; about 39 adoral membranelles; 18 frontoventral transverse cirri in typical Oxytricha‐pattern; one right and one left marginal row, almost confluent posteriorly; dorsal ciliature in typical Oxytricha‐pattern; 8–10 caudal cirri arranged in three rows, one each at the posterior end of dorsal kineties 1, 2, and 4, indistinguishable from marginal cirri in life. The morphogenetic process in N. apoaustralis n. sp. is consistent with that of the type species, Notohymena rubescens Blatterer and Foissner, 1988. Phylogenetic analyses based on small subunit rDNA sequence data suggest a sister relationship between N. apoaustralis n. sp. and Paraurostyla weissei, which cluster in a clade with Rubrioxytricha ferruginea. 相似文献
148.
149.
Lois A. St Brice Xiongjun Shao Javier A. Izquierdo 《Preparative biochemistry & biotechnology》2013,43(2):206-216
The affinity digestion process for cellulase purification consisting of binding to amorphous cellulose, and amorphous cellulose hydrolysis in the presence of dialysis (Morag et al., 1991), was optimized to obtain high activity recoveries and consistent protein recoveries in the isolation of Clostridium thermocellum cellulase. Experiments were conducted using crude supernatant prepared from C. thermocellum grown on either Avicel or cellobiose. While no difference was observed between Avicel-grown or cellobiose-grown cellulase in the adsorption step, differences were observed during the hydrolysis step. The optimal amorphous cellulose loading was found to be 3 mg amorphous cellulose per milligram supernatant protein. At this loading, 90–100% of activity in the crude supernatant was adsorbed. Twenty-four-hour incubation with the amorphous cellulose during the adsorption stage was found to result in maximal and stable adsorption of activity to the substrate. By fitting the adsorption data to the Langmuir model, an adsorption constant of 410 L/g and a binding capacity of 0.249 g cellulase/g cellulose were obtained. The optimal length of time for hydrolysis was found to be 3 hr for cellulase purified from Avicel cultures and 4 hr for cellulase purified from cellobiose cultures. These loadings and incubation times allowed for more than 85% activity recovery. 相似文献
150.