全文获取类型
收费全文 | 12062篇 |
免费 | 776篇 |
国内免费 | 7篇 |
出版年
2024年 | 15篇 |
2023年 | 38篇 |
2022年 | 115篇 |
2021年 | 232篇 |
2020年 | 131篇 |
2019年 | 205篇 |
2018年 | 295篇 |
2017年 | 244篇 |
2016年 | 424篇 |
2015年 | 615篇 |
2014年 | 745篇 |
2013年 | 797篇 |
2012年 | 1066篇 |
2011年 | 1042篇 |
2010年 | 648篇 |
2009年 | 498篇 |
2008年 | 787篇 |
2007年 | 674篇 |
2006年 | 611篇 |
2005年 | 558篇 |
2004年 | 570篇 |
2003年 | 452篇 |
2002年 | 360篇 |
2001年 | 355篇 |
2000年 | 327篇 |
1999年 | 227篇 |
1998年 | 89篇 |
1997年 | 77篇 |
1996年 | 49篇 |
1995年 | 48篇 |
1994年 | 38篇 |
1993年 | 29篇 |
1992年 | 83篇 |
1991年 | 54篇 |
1990年 | 44篇 |
1989年 | 48篇 |
1988年 | 27篇 |
1987年 | 28篇 |
1986年 | 21篇 |
1985年 | 23篇 |
1984年 | 13篇 |
1983年 | 15篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 15篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1970年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Conditions were evaluated for optimum cryopreservation of primary chicken embryo kidney (CEK) cells. The recovery of viable
CEK cells was best (50.8% viability) when the concentration of dimethyl sulfoxide (DMSO) in the freezing medium was 20% (v/v).
The viability of primary CEK cells was not influenced by the concentration of calf serum in the freezing medium, the duration
of storage at −70°C before storage in liquid nitrogen, cell concentration, or the method of addition or dilution of DMSO.
Thawed cells recovered and grew in complete growth medium similarly to cells freshly isolated from kidney, and influenza viruses
produced plaques in the monolayer. The cryopreservation procedures described here may facilitate maintenance of a standard
stock of primary CEK cells for laboratories where preparation of primary CEK cells is not an option. 相似文献
952.
Rogers JV Choi YW Richter WR Rudnicki DC Joseph DW Sabourin CL Taylor ML Chang JC 《Journal of applied microbiology》2007,103(4):1104-1112
AIMS: To evaluate the decontamination of Bacillus anthracis, Bacillus subtilis, and Geobacillus stearothermophilus spores on indoor surface materials using formaldehyde gas. METHODS AND RESULTS: B. anthracis, B. subtilis, and G. stearothermophilus spores were dried on seven types of indoor surfaces and exposed to approx. 1100 ppm formaldehyde gas for 10 h. Formaldehyde exposure significantly decreased viable B. anthracis, B. subtilis, and G. stearothermophilus spores on all test materials. Significant differences were observed when comparing the reduction in viable spores of B. anthracis with B. subtilis (galvanized metal and painted wallboard paper) and G. stearothermophilus (industrial carpet and painted wallboard paper). Formaldehyde gas inactivated>or=50% of the biological indicators and spore strips (approx. 1x10(6) CFU) when analyzed after 1 and 7 days. CONCLUSIONS: Formaldehyde gas significantly reduced the number of viable spores on both porous and nonporous materials in which the two surrogates exhibited similar log reductions to that of B. anthracis on most test materials. SIGNIFICANCE AND IMPACT OF THE STUDY: These results provide new comparative information for the decontamination of B. anthracis spores with surrogates on indoor surfaces using formaldehyde gas. 相似文献
953.
Lim SJ Lee YJ Park DH Lee E Choi MK Park W Chun KH Choi HG Cho JS 《Apoptosis : an international journal on programmed cell death》2007,12(2):423-431
Sulindac sulfone (also known as exisulind) and its chemical derivatives are promising anticancer agents capable of inducing
apoptosis in a variety of malignant cell types with minimal toxicity to normal cells. Here, we tested the ability of alpha-tocopheryl
succinate (TOS), another promising anticancer agent, to sensitize colon cancer cells to exisulind-induced apoptosis. We found
that sub-apoptotic doses of TOS greatly enhanced exisulind-induced growth suppression and apoptosis in the HCT116, LoVo and
SNU-C4 human colon cancer cell lines. Our results revealed that this was accounted for primarily by an augmented cleavage
of poly(ADP-ribose) polymerase (PARP) and enhanced activation of caspase-8, -9 and -3. Pretreatment with z-VAD-FMK (a pan-caspase inhibitor), z-IETD-FMK (a caspase-8 inhibitor) or z-LEHD-FMK (a caspase-9 inhibitor) blocked TOS and exisulind cotreatment-induced PARP cleavage and apoptosis. Furthermore,
TOS/exisulind cotreatment induced JNK phosphorylation, while pretreatment with SP600151 (a JNK inhibitor) partially blocked
cotreatment-induced caspase-dependent PARP cleavage and apoptosis. Taken together, these findings indicate that TOS sensitizes
human colon cancer cells to exisulind-induced apoptosis. Apoptotic synergy induced by exisulind plus TOS seems likely to be
mediated through a mechanism involving activation of caspases and JNK.
S.-J. Lim, Y.-J. Lee both authors are contributed equally to this study. 相似文献
954.
Choi MR Groot M Drexler HC 《Apoptosis : an international journal on programmed cell death》2007,12(11):2025-2035
RhoGDI2, a cytosolic regulator of Rho GTPase, is cleaved during apoptosis in a caspase-3 dependent fashion. By using 2D-gel
electrophoresis, mass spectrometry and Western blotting we investigate in this paper the functional consequences of RhoGDI2
processing. We can show that loss of the N-terminal 19 amino acids results in a shift of the isoelectric point of the truncated
RhoGDI2 (NΔ19) to a more basic value due to the removal of 9 acidic amino acids from the N-terminus, which may be responsible
for enhanced retention of the N-terminally truncated protein within the nuclear compartment. Fusion of the p53 nuclear export
signaling sequence MFRELNEALELK to NΔ19 (NΔ19NES) abolished its apoptosis promoting properties, while overexpression of NΔ19
significantly increased the susceptibility to apoptosis induction by the proteasome inhibitor PSI and by staurosporine. These
results suggest that cleavage of RhoGDI2 by caspase-3 is not a functionally irrelevant bystander effect of caspase activation
during apoptosis, but rather expedites progression of the apoptotic process. 相似文献
955.
Regulation of cyclin-dependent kinase inhibitor p21<Superscript>WAF1/CIP1</Superscript> by protein kinase Cδ-mediated phosphorylation 总被引:1,自引:0,他引:1
Oh YT Chun KH Park BD Choi JS Lee SK 《Apoptosis : an international journal on programmed cell death》2007,12(7):1339-1347
Cyclin-dependent kinase (CDK) inhibitor p21WAF1/CIP1(-/-)-null mice have an increased incidence of tumor formation. Here, we demonstrate that p21WAF1/CIP1 is unstable in HeLa cells treated with siRNA duplexes that target PKCδ. PKCδ phosphorylates p21WAF1/CIP1 at a serine residue (146Ser) located in its C-terminal domain. In cells treated with 12-O-tetradecanoylphorbol 13-acetate, the levels of both p21WAF1/CIP1 and its 146Ser-phosphorylated form increased significantly. We also show that a substitution, resulting from a single nucleotide polymorphism
(SNP) at 149Asp found in certain cancer patients, strongly compromises PKCδ-mediated phosphorylation at 146Ser and results in cells that are relatively resistant to TNFα-induced apoptosis. Thus, post-translational phosphorylation
of p21WAF1/CIP1 is important from an apoptotic cell death, and may also have patho-physiological relevance for the development of human cancer. 相似文献
956.
AIMS: Enhancement of algicidal activity by immobilization of algicidal bacteria antagonistic to Stephanodiscus hantzschii. METHODS AND RESULTS: In laboratory studies, A diatom-lysing bacterium, Pseudomonas fluorescens HYK0210-SK09 showed strong algicidal activity against S. hantzschii, but a natural mesocosm study revealed that this bacterium failed to fully control natural blooms of Stephanodiscus at the low water temperatures that favour these blooms. Here, we sought to develop an effective immobilization strategy for enhancing the algicidal activity of HYK0210-SK09 in the natural setting. Bacterium HYK0210-SK09 was immobilized with various carriers including agar, alginate, polyurethane and cellulose sponge. The bacterial cells immobilized with cellulose sponge (CIS) induced more rapid and complete lysis of S. hantzschii than other carriers, and had a higher packing ability than polyurethane. Furthermore, CIS-immobilized cells showed higher lysis of S. hantzschii at the same concentrations as that of free cells (< or =1 x 10(7) cells ml(-1)), and had especially strong algicidal activity at the low temperatures (<10 degrees C). Based on these laboratory studies, we assessed the possible application of HYK0210-SK09 cells in the field by performing a mesocosm study during the winter season. The CIS-immobilized cells with species-specific activity towards the genera Stephanodiscus showed extremely high algicidal activity (up to 95%) against a bloom of Stephanodiscus hantzschii even at low water temperatures, because of high cell packing and subsequent cell protection against low temperatures and predators, whereas free cells showed negligible algicidal activities under these conditions. CONCLUSION: Immobilizing cells of HYK0210-SK09 in CIS foam, rather than in the other matrices tested, could achieve more efficient control of Stephanodiscus blooms and showed a significant algicidal activity on in vitro and in vivo blooms, even at low water temperature. SIGNIFICANCE AND IMPACT OF THE STUDY: Collectively, these results indicate that CIS of algicidal bacteria may form an important strategy for effective management of Stephanodiscus blooms at low water temperatures. 相似文献
957.
Choi YJ Lee EM Park JM Lee KM Han SH Kim JK Lee SH Song HJ Choi MS Kim IS Park KH Jang WJ 《Microbiology and immunology》2007,51(3):307-312
This study revealed the presence of various rickettsial agents in mites from wild rodents collected in Southern Jeolla Province, Korea, by nested polymerase chain reaction (PCR) and sequence analysis of a partial citrate synthase and rickettsia outer membrane protein B genes. Rickettsial agents closely related to the Rickettsia species TwKM02, R. australis, and the Rickettsia species Cf15 were successfully identified in this study, for the first time in Korea, and R. japonica, R. akari, R. conorii, R. felis, and R. typhi were also detected, as previously described. The data presented in this paper extend knowledge on the geographic distribution of SFG rickettsiae in eastern Asia and it may necessary to consider the role of mites in rickettsial transmission. 相似文献
958.
Min BW Cho YN Song MJ Noh TK Kim BK Chae WK Park YS Choi YD Harn CH 《Plant cell reports》2007,26(3):337-344
A mannose selection system was adapted for use in the Agrobacterium-mediated transformation of Chinese cabbage. This system makes use of the pmi gene that encodes phosphomannose isomerase, which converts mannose-6-phosphate to fructose-6-phosphate. Hypocotyl explants
from 4–5-day-old seedlings of Chinese cabbage inbred lines were pre-cultured for 2–3 days and then infected with Agrobacterium. Two genes (l-guluno-γ-lactone oxidase, GLOase, and jasmonic methyl transferase, JMT) were transformed into Chinese cabbage using the transformation procedure developed in this study. We found that supplementing
the media with 7 g l−1 mannose and 2% sucrose provides the necessary conditions for the selection of transformed plants from nontransformed plants.
The transformation rates were 1.4% for GLOase and 3.0% for JMT, respectively. The Southern blot analysis revealed that several independent transformants (T
0) were obtained from each transgene. Three different inbred lines were transformed, and most of the T
1 plants had normal phenotypes. The transformation method presented here for Chinese cabbage using mannose selection is efficient
and reproducible, and it can be useful to introduce a desirable gene(s) into commercially useful inbred lines of Chinese cabbage. 相似文献
959.
Homeobox genes are essential regulators of plant development. ATHB23, a class I homeodomain leucine zipper gene of Arabidopsis, was found to be induced by treatment with the phytohormone gibberellin (GA). In order to clarify its role in development, we performed a histochemical analysis of transgenic plants containing a construct with a GUS::GFP reporter under the control of the 1.5 kb upstream region of ATHB23. The construct was mainly expressed in young leaves and the styles of flowers but not in mature leaves. Microscopic examination of young leaves revealed that it was expressed in the adaxial domain of leaf primordia and the rib meristem. Expression of ATHB23, like that of GA5 encoding GA 20-oxidase, was reduced in mutants related to adaxial-abaxial leaf polarity (phb-1d, se-2, and kan1 kan2). Reduced expression of the GUS::GFP reporter gene was also observed in an se-2 background. These results indicate that ATHB23 is under the control of GA and other activators such as PHB, and is involved in establishing polarity during leaf development. 相似文献
960.
Hong OK Lee SH Rhee M Ko SH Cho JH Choi YH Song KH Son HY Yoon KH 《Journal of cellular biochemistry》2007,101(3):665-675
Pancreatic islet fibrosis observed in Type 2 diabetes is one of the major factors leading to progressive beta-cell loss and dysfunction. Despite its importance, the mechanism of islet-restricted fibrogenesis associated with pancreatic stellate cell (PSC) activation and proliferation remains to be defined. Therefore, we studied whether the islet-specific environment represented by hyperglycemia and hyperinsulinemia had additive effects on the activation and proliferation of cultured rat PSCs. Cells were stimulated to activate and proliferate with glucose and insulin, either individually or concomitantly. Both stimuli promoted PSC proliferation and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation independently, but an additive effect was also demonstrated. Blockade of ERK signaling by the mitogen-activated protein kinase kinase (MEK) inhibitor, U0126, suppressed both glucose- and insulin-induced ERK 1/2 phosphorylation and PSC proliferation. Glucose and insulin-induced ERK 1/2 phosphorylation also stimulated connective tissue growth factor gene expression. Thus, hyperglycemia and hyperinsulinemia are two crucial mitogenic factors that activate and proliferate PSCs, and the presence of both states will amplify this response. 相似文献