全文获取类型
收费全文 | 9365篇 |
免费 | 859篇 |
国内免费 | 414篇 |
出版年
2023年 | 31篇 |
2022年 | 109篇 |
2021年 | 212篇 |
2020年 | 176篇 |
2019年 | 222篇 |
2018年 | 252篇 |
2017年 | 202篇 |
2016年 | 284篇 |
2015年 | 413篇 |
2014年 | 440篇 |
2013年 | 531篇 |
2012年 | 700篇 |
2011年 | 642篇 |
2010年 | 410篇 |
2009年 | 389篇 |
2008年 | 540篇 |
2007年 | 460篇 |
2006年 | 420篇 |
2005年 | 399篇 |
2004年 | 406篇 |
2003年 | 419篇 |
2002年 | 393篇 |
2001年 | 226篇 |
2000年 | 174篇 |
1999年 | 161篇 |
1998年 | 100篇 |
1997年 | 96篇 |
1996年 | 67篇 |
1995年 | 83篇 |
1994年 | 67篇 |
1993年 | 57篇 |
1992年 | 59篇 |
1991年 | 53篇 |
1990年 | 54篇 |
1989年 | 50篇 |
1988年 | 40篇 |
1987年 | 38篇 |
1986年 | 25篇 |
1985年 | 28篇 |
1984年 | 35篇 |
1983年 | 34篇 |
1982年 | 32篇 |
1981年 | 42篇 |
1980年 | 31篇 |
1979年 | 31篇 |
1978年 | 50篇 |
1974年 | 28篇 |
1973年 | 35篇 |
1971年 | 25篇 |
1966年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
In a study of the effect of glycerin in transport media on Vibrio parahaemolyticus and Salmonella, it was found that a concentration of 30% glycerin was highly inhibitory for V. parahaemolyticus and to a lesser degree for Salmonella. The incorporation of peptone or human feces in media did not reduce the inhibitory effect of glycerin. In media with 15% glycerin, viable counts of V. parahaemolyticus and Salmonella increased after 24 hr of incubation both in the presence and absence of feces. Due to the concurrent increase in the total bacterial count in the media containing feces, no enrichment effect was noted. 相似文献
2.
3.
Regina M. Santella Dezider Grunberger Alfred Nordheim Alexander Rich 《Biochemical and biophysical research communications》1982,106(4):1226-1232
Poly(dG-m5dC)·poly(dG-m5dC) was modified by treatment with N-acetoxy-N-2-acetylaminofluorene (N-Aco-AAF) and its conformation examined by circular dichroism (CD) and susceptibility to S1 nuclease digestion. A sample with a modification level of 10% shows a CD spectrum characteristic of the Z form and is resistant to digestion by S1 nuclease. The relative reactivity of several polymers with N-Aco-AAF was shown to follow the order of ease of formation of Z DNA: poly(dG-m5dC)·poly(dG-m5dC) > poly(dG-dC)·poly(dG-dC) > poly(dG)·poly(dC). This suggests that AAF reacts more readily with Z DNA than B DNA. 相似文献
4.
Barbora Straková Michail Rovatsos Lukáš Kubička Lukáš Kratochvíl 《BioEssays : news and reviews in molecular, cellular and developmental biology》2020,42(10):2000050
Frequent independent origins of environmental sex determination (ESD) are assumed within amniotes. However, the phylogenetic distribution of sex-determining modes suggests that ESD is likely very ancient and may be homologous across ESD groups. Sex chromosomes are demonstrated to be old and stable in endothermic (mammals and birds) and many ectothermic (non-avian reptiles) lineages, but they are mostly non-homologous between individual amniote lineages. The phylogenetic pattern may be explained by ancestral ESD with multiple transitions to later evolutionary stable genotypic sex determination. It is pointed out here that amniote ESD shares several key aspects with sequential hermaphroditism of fishes such as a lack of sex differences in genomes, biased population sex ratios, and potentially also molecular mechanism related to general stress responses. Here, it is speculated that ESD evolves via a heterochronic shift of the sensitive period of sex change from the adult to the embryonic stage in a hermaphroditic amniote ancestor. Also see the video abstract here https://youtu.be/q2mjtlCefu4 . 相似文献
5.
6.
Jun‐juan Wang Qi‐min Zhang Wei‐wei Ni Xin Zhang Ying Li Ai‐li Li Peng Du Chun Li Su‐su Yu 《Microbiology and immunology》2019,63(8):303-315
We investigated the correlation between the beneficial effect of Lactobacillus acidophilus on gut microbiota composition, metabolic activities, and reducing cow's milk protein allergy. Mice sensitized with β‐lactoglobulin (β‐Lg) were treated with different doses of L. acidophilus KLDS 1.0738 for 4 weeks, starting 1 week before allergen induction. The results showed that intake of L. acidophilus significantly suppressed the hypersensitivity responses, together with increased fecal microbiota diversity and short‐chain fatty acids (SCFAs) concentration (including propionate, butyrate, isobutyrate, and isovalerate) when compared with the allergic group. Moreover, treatment with L. acidophilus induced the expression of SCFAs receptors, G‐protein–coupled receptors 41 (GPR41) and 43 (GPR43), in the spleen and colon of the allergic mice. Further analysis revealed that the GPR41 and GPR43 messenger RNA expression both positively correlated with the serum concentrations of transforming growth factor‐β and IFN‐γ (p < .05), but negatively with the serum concentrations of IL‐17, IL‐4, and IL‐6 in the L. acidophilus–treated group compared with the allergic group (p < .05). These results suggested that L. acidophilus protected against the development of allergic inflammation by improving the intestinal flora, as well as upregulating SCFAs and their receptors GPR41/43. 相似文献
7.
The kinetics of the electrostatically induced phase transition of dimyristoyl phosphatidic acid bilayers was followed using the stopped-flow technique. The phase transition was triggered by a fast change in the pH or the magnesium ion concentration and followed by recording the time dependence of the absorbance. When the phase transition was induced by a pH jump the time course of the absorbance could be described by two exponentials, their time constants displaying the for cooperative processes characteristic maximum at the transition midpoint. The time constants are in the 10 and 100 ms range for the H+ triggered transition from the fluid to the ordered state. A third slower process shows no appreciable temperature dependence and is probably caused by vesicle aggregation. For the OH--induced transition fron the ordered to the fluid state the time constants are in the 100 and 1000 ms range. The fluid-ordered transition could also be triggered by addition of magnesium ions. Of the several observed processes only the fastest in the 10–100 ms time range could definitely be assigned to the fluid-ordered transition while the others are due to aggregation phenomena. The experimental data were compared with results obtained from pressure jump experiments and could be interpreted on the basis of theories for non-equilibrium relaxation. 相似文献
8.
9.
Alfred Fischel 《Development genes and evolution》1915,41(2):312-322
Ohne Zusammenfassung 相似文献
10.