全文获取类型
收费全文 | 2961篇 |
免费 | 218篇 |
国内免费 | 1篇 |
专业分类
3180篇 |
出版年
2024年 | 1篇 |
2023年 | 16篇 |
2022年 | 34篇 |
2021年 | 58篇 |
2020年 | 39篇 |
2019年 | 51篇 |
2018年 | 97篇 |
2017年 | 76篇 |
2016年 | 107篇 |
2015年 | 203篇 |
2014年 | 234篇 |
2013年 | 236篇 |
2012年 | 288篇 |
2011年 | 240篇 |
2010年 | 154篇 |
2009年 | 153篇 |
2008年 | 193篇 |
2007年 | 193篇 |
2006年 | 148篇 |
2005年 | 129篇 |
2004年 | 162篇 |
2003年 | 122篇 |
2002年 | 103篇 |
2001年 | 17篇 |
2000年 | 16篇 |
1999年 | 23篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有3180条查询结果,搜索用时 0 毫秒
11.
12.
Alkaline-oxidative (A/O) pretreatment and enzymatic saccharification were optimized for bioethanol fermentation from water hyacinth by Saccharomyces cerevisiae. Water hyacinth was subjected to A/O pretreatment at various NaOH and H(2)O(2) concentrations and reaction temperatures for the optimization of bioethanol fermentation by S. cerevisiae. The most effective condition for A/O pretreatment was 7% (w/v) NaOH at 100 °C and 2% (w/v) H(2)O(2). The carbohydrate content was analyzed after reaction at various enzyme concentrations and enzyme ratios using Celluclast 1.5 L and Viscozyme L to determine the effective conditions for enzymatic saccharification. After ethanol fermentation using S. cerevisiae KCTC 7928, the concentration of glucose, ethanol and glycerol was analyzed by HPLC using a RI detector. The yield of ethanol in batch fermentation was 0.35 g ethanol/g biomass. Continuous fermentation was carried out at a dilution rate of 0.11 (per h) and the ethanol productivity was 0.77 [g/(l h)]. 相似文献
13.
Production of nattokinase by high cell density fed-batch culture of Bacillus subtilis 总被引:1,自引:0,他引:1
Bacillus subtilis was cultivated to high cell density for nattokinase production by pH-stat fed-batch culture. A concentrated mixture solution
of glucose and peptone was automatically added by acid-supplying pump when culture pH rose above high limit. Effect of the
ratio of glucose to peptone in feeding solution was investigated on cell growth and nattokinase production by changing the
ratio from 0.2 to 5 g glucose/g peptone. The highest cell concentration was 77 g/L when the ratio was 0.2 g glucose/g peptone.
Cell concentration decreased with increasing the ratio of glucose to peptone in feeding solution, while the optimum condition
existed for nattokinase production. The highest nattokinase activity was 14,500 unit/mL at a ratio of 0.33 g glucose/g peptone,
which was 4.3 times higher than that in batch culture. 相似文献
14.
15.
Misun Won Soyoun Kim Seunghwan Lee Chuljung Kim Hyunsu Kim Moohyung Jun Kyung Bin Song 《Biotechnology letters》2000,22(14):1165-1168
To study the characteristics of recombinant thin aggregative fimbriae of salmonella and to develop a vaccine for salmonella infections, the AgfA subunit gene was amplified from Salmonella entiritidis using PCR. Maltose binding protein (MBP)-AgfA fusion protein was over-produced in E. coli and purified. Antibody against MBP-AgfA was prepared and its immunogenicity was studied. 相似文献
16.
Microbial flocculant from Arcuadendron sp. TS-49 总被引:9,自引:0,他引:9
Summary A flocculant was purified from the culture broth of Archuadendron sp. TS-49 by a series of precipitations with acetone, 60% ammonium sulfate-butanol, salting-out by dialysis, and cetylpyridinium chloride. The flocculating activity was observed most highly at pH 3.0 and markedly enhanced by the addition of salts, especially in the case of FeCl3 or FeSO4. This bioflocculant efficiently flocculated all tested solids, including various microorganisms and organic/ inorganic materials. Qualitative analyses of the bioflocculant showed that it might contain hexosamine, uronic acid, neutral sugar, and protein. 相似文献
17.
Nakashima A Maruki Y Imamura Y Kondo C Kawamata T Kawanishi I Takata H Matsuura A Lee KS Kikkawa U Ohsumi Y Yonezawa K Kamada Y 《PloS one》2008,3(5):e2223
The target of rapamycin (Tor) protein plays central roles in cell growth. Rapamycin inhibits cell growth and promotes cell cycle arrest at G1 (G0). However, little is known about whether Tor is involved in other stages of the cell division cycle. Here we report that the rapamycin-sensitive Tor complex 1 (TORC1) is involved in G2/M transition in S. cerevisiae. Strains carrying a temperature-sensitive allele of KOG1 (kog1-105) encoding an essential component of TORC1, as well as yeast cell treated with rapamycin show mitotic delay with prolonged G2. Overexpression of Cdc5, the yeast polo-like kinase, rescues the growth defect of kog1-105, and in turn, Cdc5 activity is attenuated in kog1-105 cells. The TORC1-Type2A phosphatase pathway mediates nucleocytoplasmic transport of Cdc5, which is prerequisite for its proper localization and function. The C-terminal polo-box domain of Cdc5 has an inhibitory role in nuclear translocation. Taken together, our results indicate a novel function of Tor in the regulation of cell cycle and proliferation. 相似文献
18.
So Eun Park Jong Cheol Kim Se Jin Lee Mi Rong Lee Sihyeon Kim Dongwei Li Sehyeon Baek Ji Hee Han Jeong Jun Kim Kyung Bon Koo Tae Young Shin Jae Su Kim 《Journal of Asia》2018,21(4):1102-1109
Entomopathogenic fungi have great potential to control agricultural and horticultural insect pests, however optimizing conidial production systems to demonstrate high productivity and stability still needs additional efforts for successful field application and industrialization. Although many virulent entomopathogenic fungal isolates have been viewed as potential candidates in a laboratory environment, very few of the isolates are being used in practice for application in agricultural fields as commercial products. I. javanicus is an entomopathogenic fungus that is parasitic to various diverse coleopteran and lepidopteran insects and thought good candidate as biopesticdes. In this work, the basic characteristics of two entomopathogenic fungi, I. javanica FG340 and Pf04, were investigated in morphological examinations, genetic identification, and virulence against Thrips palmi, and then the feasibility of various grains substrates for conidial production was assessed, particularly focusing on conidial productivity and thermotolerance. Isaria javanica FG340 and Pf04 conidia were solid-cultured on 12 grains for 14?days in a Petri dish. Of the tested Italian millet, perilla seed, millet and barley-based cultures showed high conidial production. The four-grain media yielded >1?×?109 conidia/g of I. javanica FG340 and Pf04. Pf04 strain had enhanced thermotolerance up to 45?°C when cultured on Italian millet. In application, it was easy to make a conidial suspension using the cultured grains, and several surfactants were tested to release the conidia. This work suggests several possible inexpensive grain substrates by which to promote conidial production combined with enhanced stability against exposure to high temperature. 相似文献
19.
In this work we investigated the antibacterial properties of differently shaped silver nanoparticles against the gram-negative bacterium Escherichia coli, both in liquid systems and on agar plates. Energy-filtering transmission electron microscopy images revealed considerable changes in the cell membranes upon treatment, resulting in cell death. Truncated triangular silver nanoplates with a {111} lattice plane as the basal plane displayed the strongest biocidal action, compared with spherical and rod-shaped nanoparticles and with Ag(+) (in the form of AgNO(3)). It is proposed that nanoscale size and the presence of a {111} plane combine to promote this biocidal property. To our knowledge, this is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, and our results demonstrate that silver nanoparticles undergo a shape-dependent interaction with the gram-negative organism E. coli. 相似文献