全文获取类型
收费全文 | 5216篇 |
免费 | 408篇 |
国内免费 | 5篇 |
专业分类
5629篇 |
出版年
2023年 | 21篇 |
2022年 | 59篇 |
2021年 | 96篇 |
2020年 | 71篇 |
2019年 | 70篇 |
2018年 | 131篇 |
2017年 | 109篇 |
2016年 | 164篇 |
2015年 | 293篇 |
2014年 | 320篇 |
2013年 | 348篇 |
2012年 | 449篇 |
2011年 | 405篇 |
2010年 | 269篇 |
2009年 | 231篇 |
2008年 | 329篇 |
2007年 | 290篇 |
2006年 | 273篇 |
2005年 | 246篇 |
2004年 | 252篇 |
2003年 | 242篇 |
2002年 | 160篇 |
2001年 | 110篇 |
2000年 | 101篇 |
1999年 | 90篇 |
1998年 | 29篇 |
1997年 | 35篇 |
1996年 | 36篇 |
1995年 | 25篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 37篇 |
1991年 | 26篇 |
1990年 | 18篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1975年 | 12篇 |
1974年 | 9篇 |
1971年 | 6篇 |
排序方式: 共有5629条查询结果,搜索用时 0 毫秒
991.
Seung Hak Lee Chiyul Yoon Sun Gun Chung Hee Chan Kim Youngbin Kwak Hee-won Park Keewon Kim 《PloS one》2015,10(6)
Range of motion (ROM) measurements are essential for the evaluation for and diagnosis of adhesive capsulitis of the shoulder (AC). However, taking these measurements using a goniometer is inconvenient and sometimes unreliable. The Kinect (Microsoft, Seattle, WA, USA) is gaining attention as a new motion detecting device that is nonintrusive and easy to implement. This study aimed to apply Kinect to measure shoulder ROM in AC; we evaluated its validity by calculating the agreement of the measurements obtained using Kinect with those obtained using goniometer and assessed its utility for the diagnosis of AC. Both shoulders of 15 healthy volunteers and affected shoulders of 12 patients with AC were included in the study. The passive and active ROM of each were measured with a goniometer for flexion, abduction, and external rotation. Their active shoulder motions for each direction were again captured using Kinect and the ROM values were calculated. The agreement between the two measurements was tested with the intraclass correlation coefficient (ICC). Diagnostic performance using the Kinect ROM was evaluated with Cohen’s kappa value. The cutoff values of the limited ROM were determined in the following ways: the same as passive ROM values, reflecting the mean difference, and based on receiver operating characteristic curves. The ICC for flexion/abduction/external rotation between goniometric passive ROM and the Kinect ROM were 0.906/0.942/0.911, while those between active ROMs and the Kinect ROMs were 0.864/0.932/0.925. Cohen’s kappa values were 0.88, 0.88, and 1.0 with the cutoff values in the order above. Measurements of the shoulder ROM using Kinect show excellent agreement with those taken using a goniometer. These results indicate that the Kinect can be used to measure shoulder ROM and to diagnose AC as an alternative to goniometer. 相似文献
992.
993.
Lee J Nam S Hwang SB Hong M Kwon JY Joeng KS Im SH Shim J Park MC 《Journal of biochemistry and molecular biology》2004,37(1):107-113
Since the completion of the genome project of the nematode C. elegans in 1998, functional genomic approaches have been applied to elucidate the gene and protein networks in this model organism. The recent completion of the whole genome of C. briggsae, a close sister species of C. elegans, now makes it possible to employ the comparative genomic approaches for identifying regulatory mechanisms that are conserved in these species and to make more precise annotation of the predicted genes. RNA interference (RNAi) screenings in C. elegans have been performed to screen the whole genome for the genes whose mutations give rise to specific phenotypes of interest. RNAi screens can also be used to identify genes that act genetically together with a gene of interest. Microarray experiments have been very useful in identifying genes that exhibit co-regulated expression profiles in given genetic or environmental conditions. Proteomic approaches also can be applied to the nematode, just as in other species whose genomes are known. With all these functional genomic tools, genetics will still remain an important tool for gene function studies in the post genome era. New breakthroughs in C. elegans biology, such as establishing a feasible gene knockout method, immortalized cell lines, or identifying viruses that can be used as vectors for introducing exogenous gene constructs into the worms, will augment the usage of this small organism for genome-wide biology. 相似文献
994.
O‐linked β‐N‐acetylglucosaminylation (O‐GlcNAcylation) regulates many cellular processes including the cell cycle, cell signaling, and protein trafficking. Dysregulation of O‐GlcNAcylation may be involved in the development of insulin resistance and type 2 diabetes. Therefore, it is necessary to identify cellular proteins that are induced by elevated O‐GlcNAcylation. Here, using adenosine 5′‐triphosphate affinity chromatography, we employed a proteomic approach in order to identify differentially expressed proteins in response to treatment with the O‐GlcNAcase inhibitor, O‐(2‐acetamido‐2‐deoxy‐d ‐glucopyranosylidene)amino‐N‐phenylcarbamate (PUGNAc), in mouse C2C12 myotube cells. Among 205 selected genes, we identified 68 nucleotide‐binding proteins, 14 proteins that have adenosinetriphosphatase activity, and 10 proteins with ligase activity. Upregulation of proteins, including ubiquitin‐activating enzyme E1, proteasome subunit 20S, cullin‐associated NEDD8‐dissociated protein 1, ezrin, and downregulation of the protein nucleoside diphosphate kinase B, were confirmed by western blot analysis. In particular, we found that the protein ubiquitination level in C2C12 cells was increased by PUGNAc treatment. This is the first report of quantitative proteomic profiles of myotube cells after treatment with PUGNAc, and our results demonstrate the potential to enhance understanding of the relationship between insulin resistance, O‐GlcNAc, and PUGNAc in the future. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
995.
Uncoordinated 51-like kinase 2 (ULK2), a member of the serine/threonine kinase family, plays an essential role in the regulation of autophagy in mammalian cells. Given the role of autophagy in normal cellular homeostasis and in multiple diseases, improved mechanistic insight into this process may result in the development of novel therapeutic approaches. Here, we present evidence that ULK2 associates with karyopherin beta 2 (Kapβ2) for its transportation into the nucleus. We identify a potential PY-NLS motif (774gpgfgssppGaeaapslRyvPY795) in the S/P space domain of ULK2, which is similar to the consensus PY-NLS motif (R/K/H)X2–5PY. Using a pull-down approach, we observe that ULK2 interacts physically with Kapβ2 both in vitro and in vivo. Confocal microscopy confirmed the co-localization of ULK2 and Kapβ2. Localization of ULK2 to the nuclear region was disrupted by mutations in the putative Kapβ2-binding motif (P794A). Furthermore, in transient transfection assays, the presence of the Kapβ2 binding site mutant (the cytoplasmic localization form) was associated with a substantial increase in autophagy activity (but a decrease in the in vitro serine-phosphorylation) compared with the wild type ULK2. Mutational analysis showed that the phosphorylation on the Ser1027 residue of ULK2 by Protein Kinase A (PKA) is the regulatory point for its functional dissociation from Atg13 and FIP 200, nuclear localization, and autophagy. Taken together, our observations indicate that Kapβ2 interacts with ULK2 through ULK2’s putative PY-NLS motif, and facilitates transport from the cytoplasm to the nucleus, depending on its Ser1027 residue phosphorylation by PKA, thereby reducing autophagic activity. 相似文献
996.
Kateryna Raykova Melina V. Jones Hwa Huang Paul F. Hoffman Michael Levy 《Journal of visualized experiments : JoVE》2015,(99)
The rat optic nerve is a useful model for stem cell regeneration research. Direct injection into the rat optic nerve allows delivery into the central nervous system in a minimally-invasive surgery without bone removal. This technique describes an approach to visualization and direct injection of the optic nerve following minor fascial dissection from the orbital ridge, using a conjunctival traction suture to gently pull the eye down and out. Representative examples of an injected optic nerve show successful injection of dyed beads. 相似文献
997.
The Role of Aquaporin RWC3 in Drought Avoidance in Rice 总被引:3,自引:0,他引:3
Lian Hong-Li; Yu Xin; Ye Qin; Ding Xiaodong; Kitagawa Yoshichika; Kwak Sang-Soo; Su Wei-Ai; Tang Zhang-Cheng 《Plant & cell physiology》2004,45(6):810
The above article appeared 相似文献
998.
999.
Rouhana L Wang L Buter N Kwak JE Schiltz CA Gonzalez T Kelley AE Landry CF Wickens M 《RNA (New York, N.Y.)》2005,11(7):1117-1130
Cytoplasmic polyadenylation is important in the control of mRNA stability and translation, and for early animal development and synaptic plasticity. Here, we focus on vertebrate poly(A) polymerases that are members of the recently described GLD2 family. We identify and characterize two closely related GLD2 proteins in Xenopus oocytes, and show that they possess PAP activity in vivo and in vitro and that they bind known polyadenylation factors and mRNAs known to receive poly(A) during development. We propose that at least two distinct polyadenylation complexes exist in Xenopus oocytes, one of which contains GLD2; the other, maskin and Pumilio. GLD2 protein interacts with the polyadenylation factor, CPEB, in a conserved manner. mRNAs that encode GLD2 in mammals are expressed in many tissues. In the brain, mouse, and human GLD2 mRNAs are abundant in anatomical regions necessary for long-term cognitive and emotional learning. In the hippocampus, mouse GLD2 mRNA colocalizes with CPEB1 and Pumilio1 mRNAs, both of which are likely involved in synaptic plasticity. We suggest that mammalian GLD2 poly(A) polymerases are important in synaptic translation, and in polyadenylation throughout the soma. 相似文献
1000.
To understand the functions of antioxidant enzymes during leaf development in sweetpotato, we investigated the activities
of several antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APX) and catalase
(CAT). Significant increases were observed in the activities of SOD, POX and APX during the late stage of leaf development,
whereas CAT activity increased during the early developmental stage. By RT-PCR analysis, various POX and APX genes showed
differential expression patterns during leaf development. Four POX genes swpa3, swpa4, swpa6, swpb4 and one APX gene swAPX1 exhibited high levels of gene expression during the senescence stage of leaf development, but two POX genes, swpa1 and swpa7 were preferentially expressed at both the mature green and the late senescence stages of leaf development. These results
indicate that hydrogen peroxide (H2O2)-related antioxidant enzymes are differentially regulated in the process of leaf development of sweetpotato. 相似文献