全文获取类型
收费全文 | 13339篇 |
免费 | 1056篇 |
国内免费 | 2篇 |
专业分类
14397篇 |
出版年
2023年 | 69篇 |
2022年 | 156篇 |
2021年 | 270篇 |
2020年 | 160篇 |
2019年 | 192篇 |
2018年 | 259篇 |
2017年 | 253篇 |
2016年 | 411篇 |
2015年 | 666篇 |
2014年 | 765篇 |
2013年 | 922篇 |
2012年 | 1253篇 |
2011年 | 1159篇 |
2010年 | 701篇 |
2009年 | 620篇 |
2008年 | 892篇 |
2007年 | 929篇 |
2006年 | 776篇 |
2005年 | 757篇 |
2004年 | 669篇 |
2003年 | 638篇 |
2002年 | 629篇 |
2001年 | 107篇 |
2000年 | 77篇 |
1999年 | 103篇 |
1998年 | 144篇 |
1997年 | 88篇 |
1996年 | 75篇 |
1995年 | 70篇 |
1994年 | 71篇 |
1993年 | 71篇 |
1992年 | 51篇 |
1991年 | 47篇 |
1990年 | 42篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 23篇 |
1985年 | 15篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 8篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1975年 | 8篇 |
1971年 | 11篇 |
1969年 | 8篇 |
1966年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Lackner A Genta K Koppensteiner H Herbacek I Holzmann K Spiegl-Kreinecker S Berger W Grusch M 《Analytical biochemistry》2008,380(1):146-148
Baculoviruses are widely used for protein production in insect cells, and their potential for gene transfer to mammalian cells is increasingly being recognized. Here we describe a baculovirus vector with a bicistronic mammalian expression cassette and demonstrate its suitability for efficient transient and stable protein expression in human glioblastoma cells. Bicistronic baculovirus vectors are safe, cost efficient, and easy to produce; thus, they represent an excellent gene transfer system for mammalian cells. 相似文献
92.
Erpenbeck VJ Malherbe DC Sommer S Schmiedl A Steinhilber W Ghio AJ Krug N Wright JR Hohlfeld JM 《American journal of physiology. Lung cellular and molecular physiology》2005,288(4):L692-L698
Recent studies have shown that surfactant components, in particular the collectins surfactant protein (SP)-A and -D, modulate the phagocytosis of various pathogens by alveolar macrophages. This interaction might be important not only for the elimination of pathogens but also for the elimination of inhaled allergens and might explain anti-inflammatory effects of SP-A and SP-D in allergic airway inflammation. We investigated the effect of surfactant components on the phagocytosis of allergen-containing pollen starch granules (PSG) by alveolar macrophages. PSG were isolated from Dactylis glomerata or Phleum pratense, two common grass pollen allergens, and incubated with either rat or human alveolar macrophages in the presence of recombinant human SP-A, SP-A purified from patients suffering from alveolar proteinosis, a recombinant fragment of human SP-D, dodecameric recombinant rat SP-D, or the commercially available surfactant preparations Curosurf and Alveofact. Dodecameric rat recombinant SP-D enhanced binding and phagocytosis of the PSG by alveolar macrophages, whereas the recombinant fragment of human SP-D, SP-A, or the surfactant lipid preparations had no effect. In addition, recombinant rat SP-D bound to the surface of the PSG and induced aggregation. Binding, aggregation, and enhancement of phagocytosis by recombinant rat SP-D was completely blocked by EDTA and inhibited by d-maltose and to a lesser extent by d-galactose, indicating the involvement of the carbohydrate recognition domain of SP-D in these functions. The modulation of allergen phagocytosis by SP-D might play an important role in allergen clearance from the lung and thereby modulate the allergic inflammation of asthma. 相似文献
93.
Generation of Neutralizing Human Monoclonal Antibodies against Parvovirus B19 Proteins 总被引:8,自引:6,他引:8 下载免费PDF全文
Andreas Gigler Simone Dorsch Andrea Hemauer Constance Williams Sonnie Kim Neal S. Young Susan Zolla-Pazner Hans Wolf Miroslaw K. Gorny Susanne Modrow 《Journal of virology》1999,73(3):1974-1979
Infections caused by human parvovirus B19 are known to be controlled mainly by neutralizing antibodies. To analyze the immune reaction against parvovirus B19 proteins, four cell lines secreting human immunoglobulin G monoclonal antibodies (MAbs) were generated from two healthy donors and one human immunodeficiency virus type 1-seropositive individual with high serum titers against parvovirus. One MAb is specific for nonstructural protein NS1 (MAb 1424), two MAbs are specific for the unique region of minor capsid protein VP1 (MAbs 1418-1 and 1418-16), and one MAb is directed to major capsid protein VP2 (MAb 860-55D). Two MAbs, 1418-1 and 1418-16, which were generated from the same individual have identity in the cDNA sequences encoding the variable domains, with the exception of four base pairs resulting in only one amino acid change in the light chain. The NS1- and VP1-specific MAbs interact with linear epitopes, whereas the recognized epitope in VP2 is conformational. The MAbs specific for the structural proteins display strong virus-neutralizing activity. The VP1- and VP2-specific MAbs have the capacity to neutralize 50% of infectious parvovirus B19 in vitro at 0.08 and 0.73 μg/ml, respectively, demonstrating the importance of such antibodies in the clearance of B19 viremia. The NS1-specific MAb mediated weak neutralizing activity and required 47.7 μg/ml for 50% neutralization. The human MAbs with potent neutralizing activity could be used for immunotherapy of chronically B19 virus-infected individuals and acutely infected pregnant women. Furthermore, the knowledge gained regarding epitopes which induce strongly neutralizing antibodies may be important for vaccine development. 相似文献
94.
95.
Tanja Lucas Karim Benihoud Frédéric Vigant Christoph Q. Andreas Schmidt Max G. Bachem Thomas Simmet Stefan Kochanek 《PloS one》2015,10(2)
Primary pancreatic carcinoma has an unfavourable prognosis and standard treatment strategies mostly fail in advanced cases. Virotherapy might overcome this resistance to current treatment modalities. However, data from clinical studies with oncolytic viruses, including replicating adenoviral (Ad) vectors, have shown only limited activity against pancreatic cancer and other carcinomas. Since pancreatic carcinomas have a complex tumor architecture and frequently a strong stromal compartment consisting of non-neoplastic cell types (mainly pancreatic stellate cells = hPSCs) and extracellular matrix, it is not surprising that Ad vectors replicating in neoplastic cells will likely fail to eradicate this aggressive tumor type. Because the TGFβ receptor (TGFBR) is expressed on both neoplastic cells and hPSCs we inserted the TGFBR targeting peptide CKS17 into the hypervariable region 5 (HVR5) of the capsid protein hexon with the aim to generate a replicating Ad vector with improved activity in complex tumors. We demonstrated increased transduction of both pancreatic cancer cell lines and of hPSCs and enhanced cytotoxicity in co-cultures of both cell types. Surface plasmon resonance analysis demonstrated decreased binding of coagulation factor X to CKS17-modified Ad particles and in vivo biodistribution studies performed in mice indicated decreased transduction of hepatocytes. Thus, to increase activity of replicating Ad vectors we propose to relax tumor cell selectivity by genetic hexon-mediated targeting to the TGFBR (or other receptors present on both neoplastic and non-neoplastic cells within the tumor) to enable replication also in the stromal cell compartment of tumors, while abolishing hepatocyte transduction, and thereby increasing safety. 相似文献
96.
Structures of mono-doped fullerenes, C59Xn and C59X(6mn)m (X=Bm, N+, P+, As+, Si), the isoelectronic analogues to C60 and C606m with 60 and 66 pi-electrons, have been investigated at the B3LYP/6-31G* level of density functional theory. On the basis of the computed nucleus independent chemical shifts (NICS) at the cage center and also at the center of individual rings as magnetic criteria, heterofullerenes with 60 pi-electrons are as aromatic as the parent C60, while those with 66 pi-electrons are much less aromatic than C606m. The very distinct endohedral chemical shifts of the 66 pi-electron systems may be useful to identify the heterofullerenes through their endohedral 3He NMR chemical shifts. 相似文献
97.
The complete amino acid sequence of apolipophorin-III (apoLp-III), a lipid-binding hemolymph protein from the greater wax
moth,Galleria mellonella, was determined by protein sequencing. The mature protein consists of 163 amino acid residues forming a protein of 18,075.5
Da. Its sequence is similar to apoLp-III from other Lepidopteran species, but remarkably different from the apoLp-IIIs of
insects from other orders. As shown by mass spectrometric analysis, the protein carries no modifications. Thus, all of its
known physiological functions, including its recently discovered immune response-stimulating activity, must reside in the
protein itself. 相似文献
98.
Paul D. Lampe Joerg Kistler Andreas Hefti Jacqui Bond Shirley Müller Ross G. Johnson Andreas Engel 《Journal of structural biology》1991,107(3)
Gap junction structures were assembled in vitro from octyl-β-
-glucopyranoside-solubilized components of lens fiber cell membranes. Individual pore structures (connexons), short double-membrane structures, and other amorphous material were evident in the solubilized mixture. Following the removal of the detergent by dialysis, these connexons associated to form single- and double-layered, two-dimensional hexagonal arrays (unit cell size a = B = 8.5 nm). The formation of larger arrays was dependent on the lipid-to-protein ratio and the presence of Mg2+ ions. Crystallographic analysis of electron micrographs revealed that lens junctional connexons consisted of six subunits surrounding a stain-filled channel. Upon further detergent treatment, in vitro assembled gap junctions were insoluble and formed three-dimensional stacks while other components were solubilized. SDS-PAGE and mass data from scanning transmission electron microscopy strongly suggest that a 38-kDa polypeptide, which is a processed form of the lens specific gap junction protein MP70, is a major component of the arrays. The in vitro assembly of gap junctions opens new avenues for the structural analysis of gap junctions and for the study of the intermolecular interactions of connexons during junctional assembly. 相似文献
99.
The yeast glucose transporters Hxt1, Hxt2, Hxt3, Hxt4, Hxt6, Hxt7 and Gal2, individually expressed in an hxt1-7 null mutant strain, demonstrate the phenomenon of countertransport. Thus, these transporters, which are the most important glucose transporters in Saccharomyces cerevisiae, are facilitated diffusion transporters. Apparent K(m)-values from high to low affinity, determined from countertransport and initial-uptake experiments, respectively, are: Hxt6 0.9+/-0.2 and 1.4+/-0.1 mM, Hxt7 1.3+/-0.3 and 1.9+/-0.1 mM, Gal2 1.5 and 1.6+/-0.1 mM, Hxt2 2.9+/-0.3 and 4.6+/-0.3 mM, Hxt4 6.2+/-0.5 and 6.2+/-0.3 mM, Hxt3 28.6+/-6.8 and 34.2+/-3.2 mM, and Hxt1 107+/-49 and 129+/-9 mM. From both independent methods, countertransport and initial uptake, the same range of apparent K(m)-values was obtained for each transporter. In contrast to that in human erythrocytes, the facilitated diffusion transport mechanism of glucose in yeast was symmetric. Besides facilitated diffusion there existed in all single glucose transport mutants, except for the HXT1 strain, significant first-order behaviour. 相似文献
100.
Marco Dollinger René Müller-Wille Florian Zeman Michael Haimerl Christoph Niessen Lukas P. Beyer Sven A. Lang Andreas Teufel Christian Stroszczynski Philipp Wiggermann 《PloS one》2015,10(8)