全文获取类型
收费全文 | 8880篇 |
免费 | 688篇 |
国内免费 | 830篇 |
专业分类
10398篇 |
出版年
2024年 | 40篇 |
2023年 | 169篇 |
2022年 | 364篇 |
2021年 | 594篇 |
2020年 | 385篇 |
2019年 | 430篇 |
2018年 | 438篇 |
2017年 | 325篇 |
2016年 | 409篇 |
2015年 | 579篇 |
2014年 | 663篇 |
2013年 | 688篇 |
2012年 | 844篇 |
2011年 | 742篇 |
2010年 | 468篇 |
2009年 | 391篇 |
2008年 | 430篇 |
2007年 | 373篇 |
2006年 | 315篇 |
2005年 | 263篇 |
2004年 | 214篇 |
2003年 | 182篇 |
2002年 | 150篇 |
2001年 | 106篇 |
2000年 | 112篇 |
1999年 | 106篇 |
1998年 | 87篇 |
1997年 | 85篇 |
1996年 | 55篇 |
1995年 | 56篇 |
1994年 | 71篇 |
1993年 | 34篇 |
1992年 | 38篇 |
1991年 | 33篇 |
1990年 | 26篇 |
1989年 | 31篇 |
1988年 | 16篇 |
1987年 | 15篇 |
1986年 | 10篇 |
1985年 | 20篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1951年 | 1篇 |
1950年 | 1篇 |
1948年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
942.
943.
944.
945.
Jiang?Tian Chenlei?Yu Yingwen?Xue Ruixue?Zhao Jing?Wang Lanzhou?ChenEmail author 《Biodegradation》2016,27(4-6):265-276
The novel trichlorfon (TCF)-degrading bacterium PA F-3, identified as Bacillus tequilensis, was isolated from pesticide-polluted soils by using an effective screening and domesticating procedure. The TCF biodegradation pathways of PA F-3 were also systematically elucidated. As revealed by high-performance liquid chromatography, the TCF residues in the mineral salt medium demonstrated that PA F-3 can utilize TCF as its sole carbon source and reach the highest degradation of 71.1 % at an initial TCF concentration of 200 mg/L within 5 days. The TCF degradation conditions were optimized using response surface methodology as follows: temperature, 28 °C; inoculum amount, 4 %; and initial TCF concentration, 125 mg/L. Biodegradation treatments supplemented with exogenous carbon sources and yeast extract markedly increased the microbial dry weights and TCF-degrading performance of PA F-3, respectively. Meanwhile, five metabolic products of TCF were identified through gas chromatography/mass spectrometry, and a biodegradation pathway was proposed. Results indicated that deoxidation and dehydration (including the cleavage of the P–C phosphonate bond and the C–O bond) were the preferred metabolic reactions of TCF in this TCF-degrading bacterium. 相似文献
946.
正Dear Editor,Perennial ryegrass (Lolium perenne) is a globally important forage and turf grass species that commonly forms symbiotic associations with the asexual fungal endophyte—Epichlo? festucae var. lolii. Epichlo? endophytes mutualistically interact with host plants by providing major fitness enhancements and protection from both biotic and abiotic stresses 相似文献
947.
948.
949.
Field cultivation experiments on white sesame (Sesamum indicum L.)seeds implanted with low-energy C ion showed that different dosages of C ion implantation produce different biological effects.Sesame plants in 6 different dosage groups with C ion density respectively at 1×1011,1×1012,1×1015,5×1015,1×1016,5×1016 ion/cm2 were superior to the control group in plant height,leaf number,stalk diameter and leaf size.Further,sesame plants in these groups flower and seed earlier than those in the control group,and single plant yield also increased.Of all the groups,the 5×1015 ion/cm2 dosage group yielded the best effect,whereas the 1×1017/cm2 dosage group showed an evident inhibitory effect of ion implantation on the germination and growth of the sesame seeds. 相似文献
950.
Tian Q Miller EG Jayaprakasha GK Patil BS 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,846(1-2):385-390
Recent studies have shown that citrus limonoids have potential health benefits. However, information on the absorption and metabolism of limonoids in human gastrointestinal (GI) tract is limited. In the present study we have investigated the metabolism of limonin glucoside (LG), the predominant limonoid in citrus by four microorganisms (Enterococcus fecalis, Escherichia coli, Lactobacillus salivarius, and Candida albican) widely present in the human lower GI tract. LG and metabolites in the culture medium were purified using solid phase extraction and analyzed using HPLC using UV detection at 210nm. The identity of LG was further confirmed by electrospray ionization mass spectrometry (ESI-MS). Significant metabolic activity of Escherichia coli and Candida albican on LG was observed. Several unidentified metabolites were also found in the medium. The results of the present study indicated that LG may be metabolized in the intestine by some microbes. Further studies are needed to establish the possible route of LG metabolism in the human system. 相似文献