全文获取类型
收费全文 | 19934篇 |
免费 | 1953篇 |
国内免费 | 1931篇 |
专业分类
23818篇 |
出版年
2024年 | 53篇 |
2023年 | 295篇 |
2022年 | 683篇 |
2021年 | 1067篇 |
2020年 | 848篇 |
2019年 | 923篇 |
2018年 | 935篇 |
2017年 | 663篇 |
2016年 | 887篇 |
2015年 | 1319篇 |
2014年 | 1468篇 |
2013年 | 1511篇 |
2012年 | 1744篇 |
2011年 | 1529篇 |
2010年 | 1049篇 |
2009年 | 862篇 |
2008年 | 1059篇 |
2007年 | 922篇 |
2006年 | 823篇 |
2005年 | 659篇 |
2004年 | 617篇 |
2003年 | 604篇 |
2002年 | 528篇 |
2001年 | 413篇 |
2000年 | 306篇 |
1999年 | 344篇 |
1998年 | 195篇 |
1997年 | 174篇 |
1996年 | 164篇 |
1995年 | 166篇 |
1994年 | 161篇 |
1993年 | 103篇 |
1992年 | 106篇 |
1991年 | 113篇 |
1990年 | 81篇 |
1989年 | 89篇 |
1988年 | 58篇 |
1987年 | 46篇 |
1986年 | 52篇 |
1985年 | 33篇 |
1984年 | 28篇 |
1983年 | 26篇 |
1982年 | 23篇 |
1981年 | 16篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1973年 | 4篇 |
1968年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Xiangming Yao Shiming Chen Changhong Wang Taowen Chen Jiangxiao Li Shida Xue Zhikang Deng Wenguang Zhao Bowen Nan Yiqian Zhao Kai Yang Yongli Song Feng Pan Luyi Yang Xueliang Sun 《Liver Transplantation》2024,14(10):2303422
NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) is one of the most promising solid-state electrolytes (SSEs) to achieve high-energy-density solid-state batteries (SSBs) due to its high ionic conductivity, high-voltage stability, and low cost. However, its practical application is constrained by inadequate interfacial compatibility with cathode materials and significant incompatibility with lithium metal. In this work, a cost-effective interface welding approach is reported, utilizing an innovative thermal pulse sintering (TPS) to fabricate LATP-based solid-state batteries. Initially, the rapid thermal pulses enhance the ionic conductivity of LATP SSE by inducing selective growth of LATP nanowires, effectively occupying interparticle voids. Additionally, this process results in the formation of a dense layer (GCM) comprising graphene oxide, carbon nanotubes, and MXene with a controlled Li+ transport pathway, facilitating lithium stripping and plating processes. Moreover, these thermal pulses facilitate the interfacial fusion between LATP and cathode materials, while avoiding undesired phase diffusion. As a result, SSBs with a LiCoO2 cathode deliver favorable cycle stability at 4.6 V, marking significant progress. This facile interface welding strategy represents a substantial step toward high-energy-density SSB development. 相似文献
992.
Yixiao Tian Xinyue Wang Dongyan Shao Wen Zhao Renan Chen Qingsheng Huang 《Cell biochemistry and function》2024,42(2):e3986
To establish accurate detection methods of process-specific Escherichia coli residual host cell protein (HCP) and residual host cell DNA (rcDNA) in recombinant biological preparations. Taking the purification process of GLP expressed by E. coli as a specific-process model, the HCP of empty E. coli was intercepted to immunize mice and rabbits. Using IgG from immunized rabbits as the coating antibody and mouse immune serum as the second sandwich antibody, a process-specific enzyme-linked immunosorbent assay (ELISA) for E. coli HCP was established. Targeting the 16S gene of E. coli, ddPCR was used to obtain the absolute copies of rcDNA in samples. Non-process-specific commercial ELISA kit and the process-specific ELISA established in this study were used to detect the HCP in GLP preparation. About 62% of HCPs, which should be process-specific HCPs, could not be detected by the non-process-specific commercial ELISA kit. The sensitivity of established ELISA can reach 338 pg/mL. The rcDNA could be absolutely quantitated by ddPCR, for the copies of rcDNA in three multiple diluted samples showed a reduced gradient. While the copies of rcDNA in three multiple diluted samples could not be distinguished by the qPCR. Process-specific ELISA has high sensitivity in detecting process-specific E. coli HCP. The absolutely quantitative ddPCR has much higher accuracy than the relatively quantitative qPCR, it is a nucleic acid quantitative method that is expected to replace qPCR in the future. 相似文献
993.
Nan Liu Yan-yan Yao Jin Zhang Ji-guo Zhang Chao Wu Du-juan Ouyang Chang-yong Zou Zhen-qiang Yang Ji-xiang Li 《Cell biochemistry and function》2024,42(2):e3965
A highly efficient chlorobenzene-degrading strain was isolated from the sludge of a sewage treatment plant associated with a pharmaceutical company. The strain exhibited a similarity of over 99.9% with multiple strains of Paenarthrobacter ureafaciens. Therefore, the strain was suggested to be P. ureafaciens LY. This novel strain exhibited a broad spectrum of pollutant degradation capabilities, effectively degrading chlorobenzene and other organic pollutants, such as 1, 2, 4-trichlorobenzene, phenol, and xylene. Moreover, P. ureafaciens LY co-metabolized mixtures of chlorobenzene with 1, 2, 4-trichlorobenzene or phenol. Evaluation of its degradation efficiency showed that it achieved an impressive degradation rate of 94.78% for chlorobenzene within 8 h. The Haldane–Andrews model was used to describe the growth of P. ureafaciens LY under specific pollutants and its concentrations, revealing a maximum specific growth rate (μmax) of 0.33 h−1. The isolation and characterization of P. ureafaciens LY, along with its ability to degrade chlorobenzene, provides valuable insights for the development of efficient and eco-friendly approaches to mitigate chlorobenzene contamination. Additionally, investigation of the degradation performance of the strain in the presence of other pollutants offers important information for understanding the complexities of co-metabolism in mixed-pollutant environments. 相似文献
994.
Gustin DJ Sehon CA Wei J Cai H Meduna SP Khatuya H Sun S Gu Y Jiang W Thurmond RL Karlsson L Edwards JP 《Bioorganic & medicinal chemistry letters》2005,15(6):1687-1691
A novel series of competitive, reversible cathepsin S (CatS) inhibitors was discovered and optimized. The 4-(2-keto-1-benzimidazolinyl)-piperidin-1-yl moiety was found to be an effective replacement for the 4-arylpiperazin-1-yl group found in our earlier series of CatS inhibitors. This replacement imparted improved PK properties as well as decreased off-target activity. Optimization of the ketobenzimidazole moiety led to the discovery of the lead compound JNJ 10329670, which represents a novel class of selective, noncovalent, reversible, and orally bioavailable inhibitors of cathepsin S. 相似文献
995.
As an approach to improving Fibrobacter succinogenes 1,3-1,4-beta-d-glucanase (Fsbeta-glucanase) for use in industry and to studying the structure-function relationship of the C-terminus in the enzyme, a C-terminally truncated ( approximately 10 kDa) Fsbeta-glucanase was generated using a PCR-based gene truncation method and then overexpressed in either Escherichia coli BL21(DE3) or Pichia pastoris strain X-33 host cells. The initial rate kinetics, protein folding, and thermostability of the wild-type and truncated glucanases were characterized. The truncated enzyme expressed in Pichia cells was found to be glycosylated and composed of two dominant polypeptide bands as judged by SDS-PAGE. An approximate 3-4-fold increase in the turnover rate (k(cat)), relative to that of the full-length enzyme, was detected for the purified truncated glucanases produced in E. coli (designated TF-glucanase) or Pichia host cells (designated glycosylated TF-glucanase). The glycosylated TF-glucanase is the most active known 1,3-1,4-beta-d-glucanase, with a specific activity of 10 800 +/- 200 units/mg. Similar binding affinities for lichenan (K(m) = 2.5-2.89 mg/mL) were detected for the full-length enzyme, TF-glucanase, and glycosylated TF-glucanase. Both forms of truncated glucanase retained more than 80% of their original enzymatic activity after a 10 min incubation at 90 degrees C, whereas the full-length enzyme possessed only 30% of its original enzymatic activity after the same treatment. This report demonstrates that deletion of the C-terminal region ( approximately 10 kDa) in Fsbeta-glucanase, consisting of serine-rich repeats and a basic terminal domain rich in positively charged amino acids, significantly increases the catalytic efficiency and thermotolerance of the enzyme. 相似文献
996.
Sun Z Chen J Yao H Liu L Wang J Zhang J Liu JN 《Protein expression and purification》2005,43(1):26-32
To prevent in vivo degradation, small peptides are usually expressed in fusion proteins from which target peptides can be released by proteolytic or chemical reagents. In this report, a modified Ssp dnaB mini-intein linked with a chitin binding domain tag was used as a fusion partner for production of human brain natriuretic peptide (hBNP), a hormone for the treatment of congestive heart failure. The fusion protein was expressed as an inclusion body in Escherichia coli. After refolding, the fusion protein was purified with a chitin affinity column, and dnaB mini-intein mediated peptide-bond hydrolysis was triggered by shifting the pH in the chitin column to 7.0 at 25 degrees C for 16 h, which led to the release and separation of hBNP from its fusion partner. The hBNP sample was further purified with reverse phase HPLC and its biological activity was assayed in vitro. It was found that hBNP had a potent vasodilatory effect on rabbit aortic strips with an EC(50) of (1.24+/-0.32)x10(-6)mg/ml, which was similar to that of the synthetic BNP standard. The expression strategy described here promises to produce small peptides without use of proteolytic or chemical reagents. 相似文献
997.
Li Y Schwabe RF DeVries-Seimon T Yao PM Gerbod-Giannone MC Tall AR Davis RJ Flavell R Brenner DA Tabas I 《The Journal of biological chemistry》2005,280(23):21763-21772
Two key features of atherosclerotic plaques that precipitate acute atherothrombotic vascular occlusion ("vulnerable plaques") are abundant inflammatory mediators and macrophages with excess unesterified, or "free," cholesterol (FC). Herein we show that FC accumulation in macrophages leads to the induction and secretion of two inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). The increases in TNF-alpha and IL-6 mRNA and protein were mediated by FC-induced activation of the IkappaB kinase/NF-kappaB pathway as well as activation of MKK3/p38, Erk1/2, and JNK1/2 mitogen-activated protein kinases (MAPK). Activation of IkappaB kinase and JNK1/2 was needed for the induction of both cytokines. However, MKK3/p38 signaling was specifically involved in TNF-alpha induction, and Erk1/2 signaling was required for IL-6. Most interestingly, activation of all of the signaling pathways and induction of both cytokines required cholesterol trafficking to the endoplasmic reticulum (ER). The CHOP branch of the unfolded protein response, an ER stress pathway, was required for Erk1/2 activation and IL-6 induction. In contrast, one or more other ER-related pathways were responsible for activation of p38, JNK1/2, and IkappaB kinase/NF-kappaB and for the induction of TNF-alpha. These data suggest a novel scenario in which cytokines are induced in macrophages by endogenous cellular events triggered by excess ER cholesterol rather than by exogenous immune cell mediators. Moreover, this model may help explain the relationship between FC accumulation and inflammation in vulnerable plaques. 相似文献
998.
999.
Yanchun Liang Hongyu Xie Jinjie Wu Duo Liu Shuzhong Yao 《Reproductive biology and endocrinology : RB&E》2018,16(1):122
Endometriosis is a complex and heterogeneous disorder with unknown etiology. Dysregulation of macrophages and innervation are important factors influencing the pathogenesis of endometriosis-associated pain. It is known to be an estrogen-dependent disease, estrogen can promote secretion of chemokines from peripheral nerves, enhancing the recruitment and polarization of macrophages in endometriotic tissue. Macrophages have a role in the expression of multiple nerve growth factors (NGF), which mediates the imbalance of neurogenesis in an estrogen-dependent manner. Under the influence of estrogen, co-existence of macrophages and nerves induces an innovative neuro-immune communication. Persistent stimulation by inflammatory cytokines from macrophages on nociceptors of peripheral nerves aggravates neuroinflammation through the release of inflammatory neurotransmitters. This neuro-immune interaction regulated by estrogen sensitizes peripheral nerves, leading to neuropathic pain in endometriosis. The aim of this review is to highlight the significance of estrogen in the interaction between macrophages and nerve fibers, and to suggest a potentially valuable therapeutic target for endometriosis-associated pain. 相似文献
1000.
Bioprocess and Biosystems Engineering - To overcome the contamination in open pond, microalgal strain selection should focus on species with tolerability to extreme environments. In this study, a... 相似文献