全文获取类型
收费全文 | 988篇 |
免费 | 42篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 34篇 |
2020年 | 15篇 |
2019年 | 27篇 |
2018年 | 27篇 |
2017年 | 30篇 |
2016年 | 41篇 |
2015年 | 42篇 |
2014年 | 62篇 |
2013年 | 66篇 |
2012年 | 99篇 |
2011年 | 84篇 |
2010年 | 47篇 |
2009年 | 37篇 |
2008年 | 47篇 |
2007年 | 63篇 |
2006年 | 52篇 |
2005年 | 32篇 |
2004年 | 37篇 |
2003年 | 36篇 |
2002年 | 33篇 |
2001年 | 11篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1030条查询结果,搜索用时 15 毫秒
1.
2.
3.
The role of dendritic cells in the initiation of immune responses to contact sensitizers. I. In vivo exposure to antigen 总被引:2,自引:0,他引:2
S C Knight J Krejci M Malkovsky V Colizzi A Gautam G L Asherson 《Cellular immunology》1985,94(2):427-434
Twenty-four hours after skin painting mice with picryl chloride (PIC) there was a four- to fivefold increase in the numbers of dendritic cells (DC) isolated from the lymph nodes. These DC initiated primary proliferative and cytotoxic responses when added to cultures of normal syngeneic lymph node cells. The proliferative response was enhanced when the donors of the responding lymph node cells were sensitized with the same antigen. Contact sensitivity developed in syngeneic mice injected into the footpads with 30,000-50,000 DC from lymph nodes of mice painted with picryl chloride 1 day previously. Thus, 1 day after skin painting mice, there were dendritic cells in the draining lymph nodes which were able both to initiate primary stimulation of lymphocytes in vitro and to sensitize recipient mice to give specific delayed hypersensitivity reactions. 相似文献
4.
Foreign protein expression from the commonly used SV40 promoter has been found to be primarily during the S-phase of the cell cycle. Simple mathematical models with this cell cycle phase dependent expression of foreign protein suggest that the specific production rate will be proportional to the cell growth rate, which is particularly disadvantageous in high cell density fed-batch or perfusion bioreactors. In this study we investigate this predicted relationship between the production rate and growth rate by culturing recombinant CHO cells in a continuous suspension bioreactor. One CHO cell line, GS-26, has been stably transfected with the plasmid pSVgal, which contains the E. coli lac Z gene under the control of the SV40 promoter. This GS-26 cell line was grown in suspension cultures over a range of specific growth rates in batch and continuous modes. The intracellular -galactosidase activity was assayed using a standard spectrophotometric method after breaking the cells open and releasing the enzyme. A strong growth associated relationship is found between the intracellular -galactosidase content and the specific growth rate in batch and continuous cultures, as predicted. 相似文献
5.
The role of acid phosphatases in plant phosphorus metabolism 总被引:18,自引:0,他引:18
Hydrolysis of phosphate esters is a critical process in the energy metabolism and metabolic regulation of plant cells. This review summarizes the characteristics and putative roles of plant acid phosphatase (APase). Although immunologically closely related, plant APases display remarkable heterogeneity with regards to their kinetic and molecular properties, and subcellular location. The secreted APases of roots and cell cultures are relatively non-specific enzymes that appear to be important in the hydrolysis and mobilization of Pi from extracellular phosphomonoesters for plant nutrition. Intracellular APases are undoubtedly involved in the routine utilization of Pi reserves or other Pi -containing compounds. A special class of intracellular APase exists that demonstrate a clear-cut (but generally nonabsolute) substrate selectivity. These APases are hypothesized to have distinct metabolic functions and include: phytase, phosphoglycolate phosphatase, 3-phosphoglycerate phosphatase, phosphoenolpyruvate phosphatase, and phosphotyrosyl-protein phosphatase. APase expression is regulated by a variety of developmental and environmental factors. Pi starvation induces de novo synthesis of extra- and intracellular APases in cell cultures as well as in whole plants. Recommendations are made to achieve uniformity in the analyses of the different APase isoforms normally encountered within and between different plant tissues. 相似文献
6.
A simple neural network model is proposed for kindling — the phenomenon of generating epilepsy by means of repeated electrical stimulation. The model satisfies Dale's hypothesis, incorporates a Hebb-like learning rule and has low periodic activity in absence of shocks. Many of the experimental observations are reproduced and some new experiments are suggested. It is proposed that the main reason for kindling is the formation of a large number of excitatory synaptic connections due to learning. 相似文献
7.
Sharma Shivani Kumar Amit Dhakte Priyanka Raturi Gaurav Vishwakarma Gautam Barbadikar Kalyani M. Das B. K. Shivaraj S. M. Sonah Humira Deshmukh Rupesh 《Journal of Plant Growth Regulation》2023,42(1):46-59
Journal of Plant Growth Regulation - Crop improvement in light of the rapidly changing climate and the increasing human population continues to be one of the primary concerns for researchers across... 相似文献
8.
S. P. Gautam A. K. Gupta R. Shrivastava M. Awasthi 《World journal of microbiology & biotechnology》1996,12(1):99-100
Two thermostable enzymes produced by the thermophilic fungus Paecilomyces varioti, a chitinase and laminarinase, were used to isolate protoplasts of a thermophilic fungus, Malbranchea sulfurea. The frequency of protoplast regeneration observed (35%) was considerably higher than that obtained using commercial lytic enzymes. 相似文献
9.
Summary Several clones of CHO cells, including recombinant cell lines expressing Hepatitis B surface antigen, were grown in macroporous collagen microspheres. These provided sufficient cell density in a packed bed recirculation system for phosphorus-31 nuclear magnetic resonance spectroscopic estimation of metabolite concentration. Intracellular nucleoside triphosphate as well as nucleoside tri- plus diphosphate levels were higher in the methotrexate-selected clones compared to the dhfr– cell line. 相似文献
10.
People of all ages are suffering from periodontal disease. It causes indirect damage in the oral cavity. It is of interest to evaluate the efficacy of xanthan-based chlorhexidine gel (Xan-CHX) in patients with mild-severe chronic periodontitis. Five patients with 60 sites were divided in two groups. Group A (treated with SRP) and group B (treated with Chlosite i.e., SRP + CHL). The recorded clinical parameters were Plaque index (PI), Gingival index (GI), Bleeding index (BI), and Clinical attachment Level (CAL) with sub gingival plaque subjected to microbial analysis. Significant reduction was observed in both groups. However, group B (treated with Chlosite i.e., SRP + CHL) showed statistically significant improvement on above mentioned parameters as compared to group A. Data suggest that in the treatment of periodontal disease (viz. PI, GI, BI and CAL) combination of SRP and Chlosite showed added benefits over only SRP. 相似文献