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排序方式: 共有832条查询结果,搜索用时 15 毫秒
101.
Cuong Quang Le Mercy Oyugi Ebenezer Joseph Toan Nguyen Md Hasmat Ullah Joshua Aubert Thien Phan Joseph Tran Kayunta Johnson-Winters 《Biochemistry and Biophysics Reports》2017
F420H2:NADP+ Oxidoreductase (Fno) catalyzes the reversible reduction of NADP+ to NADPH by transferring a hydride from the reduced F420 cofactor. Here, we have employed binding studies, steady-state and pre steady-state kinetic methods upon wtFno and isoleucine 135 (I135) Fno variants in order to study the effects of side chain length on the donor-acceptor distance between NADP+ and the F420 precursor, FO. The conserved I135 residue of Fno was converted to a valine, alanine and glycine, thereby shortening the side chain length. The steady-state kinetic analysis of wtFno and the variants showed classic Michaelis-Menten kinetics with varying FO concentrations. The data revealed a decreased kcat as side chain length decreased, with varying FO concentrations. The steady-state plots revealed non-Michaelis-Menten kinetic behavior when NADPH was varied. The double reciprocal plot of the varying NADPH concentrations displays a downward concave shape, while the NADPH binding curves gave Hill coefficients of less than 1. These data suggest that negative cooperativity occurs between the two identical monomers. The pre steady-state Abs420 versus time trace revealed biphasic kinetics, with a fast phase (hydride transfer) and a slow phase. The fast phase displayed an increased rate constant as side chain length decreased. The rate constant for the second phase, remained ~2 s?1 for each variant. Our data suggest that I135 plays a key role in sustaining the donor-acceptor distance between the two cofactors, thereby regulating the rate at which the hydride is transferred from FOH2 to NADP+. Therefore, Fno is a dynamic enzyme that regulates NADPH production. 相似文献
102.
103.
Jennifer S Michaelson Stephen J Demarest Brian Miller Aldo Amatucci William B Snyder Xiufeng Wu Flora Huang Samantha Phan Sharon Gao Adam Doern Graham K Farrington Alexey Lugovskoy Ingrid Joseph Veronique Bailly Xin Wang Ellen Garber Jeff Browning Scott M Glaser 《MABS-AUSTIN》2009,1(2):128-141
Bispecific antibodies (BsAbs) represent an emerging class of biologics that achieve dual targeting with a single agent. Recombinant DNA technologies have facilitated a variety of creative bispecific designs with many promising therapeutic applications; however, practical methods for producing high quality BsAbs that have good product stability, long serum half-life, straightforward purification, and scalable production have largely been limiting. Here we describe a protein-engineering approach for producing stable, scalable tetravalent IgG-like BsAbs. The stability-engineered IgG-like BsAb was envisioned to target and crosslink two TNF family member receptors, TRAIL-R2 (TNF-Related Apoptosis Inducing Ligand Receptor-2) and LTβR (Lymphotoxin-beta Receptor), expressed on the surface of epithelial tumor cells with the goal of triggering an enhanced anti-tumor effect. Our IgG-like BsAbs consists of a stability-engineered anti-LTβR single chain Fv (scFv) genetically fused to either the N- or C-terminus of the heavy chain of a full-length anti-TRAIL-R2 IgG1 monoclonal antibody. Both N- or C-terminal BsAbs were active in inhibiting tumor cell growth in vitro, and with some cell lines demonstrated enhanced activity relative to the combination of parental Abs. Pharmacokinetic studies in mice revealed long serum half-lives for the BsAbs. In murine tumor xenograft models, therapeutic treatment with the BsAbs resulted in reduction in tumor volume either comparable to or greater than the combination of parental antibodies, indicating that simultaneously targeting and cross-linking receptor pairs is an effective strategy for treating tumor cells. These studies support that stability-engineering is an enabling step for producing scalable IgG-like BsAbs with properties desirable for biopharmaceutical development.Key words: bispecific antibodies, single-chain Fv, immunoglobulins, antibody therapeutics, protein stability, pharmacokinetics, protein engineering, tumor inhibition, cancer treatment 相似文献
104.
Factors affecting the production of milk-clotting enzyme (MCE) by Bacillus subtilis (natto) Takahashi, a ready available commercial natto starter, were studied. Remarkable milk-clotting activity (MCA), 685.7 SU/ml or 12,000 SU/g, was obtained when the bacteria were cultivated in the medium containing sucrose (50 g/L) and basal salts at pH 6, 37 °C with shaking at 175 rpm for 1 day. The MCA and MCA/PA ratio of the crude enzyme obtained are comparable with those of Pfizer microbial rennin and Mucor rennin. The crude enzyme showed excellent pH and thermal stability; it retained 96% of MCA after incubation for 40 min at 40 °C and retained more than 80% of its activity between pH 4 and pH 7 for more than 30 min at 30 °C. The MCE of B. subtilis (natto) Takahashi has potential as calf rennet substitutes. 相似文献
105.
Hoang Anh Vu Phan Thi Xinh Katsushi Tokunaga 《Biochemical and biophysical research communications》2009,383(3):308-238
We recently reported that the ETV6/FLT3 fusion protein conferred interleukin-3-independent growth on Ba/F3 cells. The present study has been conducted to assess role of the juxtamembrane domain of FLT3 for signal transduction and cell transformation. The wild-type ETV6/FLT3 fusion protein in transfected cells was a constitutively activated tyrosine kinase that led to up-regulation of PIM-1 and activations of STAT5, AKT, and MAPK. Deletion of the juxtamembrane domain abrogated interleukin-3-independent growth of the transfected cells and PIM-1 up-regulation, whereas it retained compatible levels of phosphorylations of STAT5, AKT, and MAPK. Further deletion of N-terminal region of the tyrosine kinase I domain of FLT3 completely abolished these phosphorylations. Our data indicate that the juxtamembrane domain of FLT3 in ETV6/FLT3 fusion protein is critical for cell proliferation and PIM-1 up-regulation that might be independent of a requirement for signaling through STAT5, MAPK, and AKT pathways. 相似文献
106.
Eric Jain Amos Bairoch Severine Duvaud Isabelle Phan Nicole Redaschi Baris E Suzek Maria J Martin Peter McGarvey Elisabeth Gasteiger 《BMC bioinformatics》2009,10(1):136-19
Background
The UniProt consortium was formed in 2002 by groups from the Swiss Institute of Bioinformatics (SIB), the European Bioinformatics Institute (EBI) and the Protein Information Resource (PIR) at Georgetown University, and soon afterwards the website was set up as a central entry point to UniProt resources. Requests to this address were redirected to one of the three organisations' websites. While these sites shared a set of static pages with general information about UniProt, their pages for searching and viewing data were different. To provide users with a consistent view and to cut the cost of maintaining three separate sites, the consortium decided to develop a common website for UniProt. Following several years of intense development and a year of public beta testing, the domain was switched to the newly developed site described in this paper in July 2008. 相似文献107.
Constance Schultsz Nguyen Van Dung Le Thanh Hai Do Quang Ha J. S. Malik Peiris Wilina Lim Jean-Michel Garcia Nguyen Dac Tho Nguyen Thi Hoang Lan Huynh Huu Tho Phan Xuan Thao H. Rogier van Doorn Nguyen Van Vinh Chau Jeremy Farrar Menno D. de Jong 《PloS one》2009,4(11)
Background
Between 2003 and 2005, highly pathogenic avian influenza A (H5N1) viruses caused large scale outbreaks in poultry in the Ho Chi Minh City area in Vietnam. We studied the prevalence of antibodies against H5N1 in poultry workers and cullers who were active in the program in Ho Chi Minh City in 2004 and 2005.Methodology/Principal Findings
Single sera from 500 poultry workers and poultry cullers exposed to infected birds were tested for antibodies to avian influenza H5N1, using microneutralization assays and hemagglutination inhibition assay with horse blood. All sera tested negative using microneutralization tests. Three samples showed a 1∶80 titer in the hemagglutination inhibition assay.Conclusions/Significance
This study provides additional support for the low transmissibility of clade 1 H5N1 to humans, but limited transmission to highly exposed persons cannot be excluded given the presence of low antibody titers in some individuals. 相似文献108.
Tran Cong Toai Huynh Duy Thao Nguyen Phuong Thao Ciro Gargiulo Phan Kim Ngoc Pham Hung Van D. Michael Strong 《Cell and tissue banking》2010,11(3):269-280
It is well accepted that human umbilical cord blood (UCB) is a source of mesenchymal stem cells (MSCs) which are able to differentiate
into different cell phenotypes such as osteoblasts, chondrocytes, adipocytes, myocytes, cardiomyocytes and neurons. The aim
of this study was to isolate MSCs from human UCB to determine their osteogenic potential by using different kinds of osteogenic
medium. Eventually, only those MSCs cultured in osteogenic media enriched with vitamin D2 and FGF9, were positive for osteocalcin by RT-PCR. All these cells were positive for alizarin red, alkaline phosphatase and
Von Kossa. The results obtained from RT-PCR have confirmed that osteogenesis is complete by expression of the osteocalcin
marker. In conclusion, vitamin D2, at least in vitro, may replace vitamin D3 as an osteogenic stimulator factor for MSC differentiation. 相似文献
109.
G-quadruplexes and Z-DNA are two important non-B forms of DNA architecture. Results on novel structural elements, folding and unfolding kinetics, and interactions with small molecules and proteins have been reported recently for these forms. These results will enhance our understanding of the biology of these structures and provide a platform for drug design. 相似文献
110.
Genus Pteris from Vietnam and Laos is revised in this paper. Seven species newly reported from Vietnam and Laos are P.argyraea, P.sichuanensis, P.maclurei, P.pseudopellucida, P.setuloso costulata, P.morii, and P.wangiana. 相似文献