全文获取类型
收费全文 | 53281篇 |
免费 | 3871篇 |
国内免费 | 24篇 |
出版年
2023年 | 179篇 |
2022年 | 468篇 |
2021年 | 1079篇 |
2020年 | 657篇 |
2019年 | 774篇 |
2018年 | 1163篇 |
2017年 | 1032篇 |
2016年 | 1694篇 |
2015年 | 2716篇 |
2014年 | 3099篇 |
2013年 | 3392篇 |
2012年 | 4547篇 |
2011年 | 4332篇 |
2010年 | 2719篇 |
2009年 | 2468篇 |
2008年 | 3419篇 |
2007年 | 3304篇 |
2006年 | 2921篇 |
2005年 | 2643篇 |
2004年 | 2467篇 |
2003年 | 2067篇 |
2002年 | 1825篇 |
2001年 | 1343篇 |
2000年 | 1255篇 |
1999年 | 1035篇 |
1998年 | 434篇 |
1997年 | 383篇 |
1996年 | 274篇 |
1995年 | 229篇 |
1994年 | 242篇 |
1993年 | 190篇 |
1992年 | 348篇 |
1991年 | 314篇 |
1990年 | 278篇 |
1989年 | 240篇 |
1988年 | 178篇 |
1987年 | 170篇 |
1986年 | 139篇 |
1985年 | 112篇 |
1984年 | 88篇 |
1983年 | 96篇 |
1982年 | 70篇 |
1981年 | 59篇 |
1980年 | 65篇 |
1979年 | 70篇 |
1978年 | 57篇 |
1977年 | 63篇 |
1975年 | 45篇 |
1974年 | 67篇 |
1973年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
K. H. Jang J. W. Seo K. B. Song C. H. Kim S. K. Rhee 《Bioprocess and biosystems engineering》1999,21(5):453-458
Secretion of levansucrase from Zymomonas mobilis in Escherichiacoli by glycine supplement was investigated. A significant amount of levansucrase (about 25% of total activity) was found in intact whole-cells. Cell fractionation experiments showed that levansucrase was found both in the periplasmic space and in the cytoplasmic fraction of E. coli. None or only trace amounts of levansucrase was detected in the extracellular culture broth at 24 h of cultivation and it accrued with the increasing concentration of glycine in the culture medium and duration of the culture period. Optimal glycine concentration for the maximum secretion of levansucrase was in the range of 0.8-1%, in which approximately 20-50% of levansucrase was released into the extracellular fraction at 24 h of cultivation, although glycine retarded the bacterial growth. 相似文献
3.
4.
Shira Weingarten-Gabbay Susan Klaeger Siranush Sarkizova Leah R. Pearlman Da-Yuan Chen Kathleen M.E. Gallagher Matthew R. Bauer Hannah B. Taylor W. Augustine Dunn Christina Tarr John Sidney Suzanna Rachimi Hasahn L. Conway Katelin Katsis Yuntong Wang Del Leistritz-Edwards Melissa R. Durkin Christopher H. Tomkins-Tinch Pardis C. Sabeti 《Cell》2021,184(15):3962-3980.e17
- Download : Download high-res image (225KB)
- Download : Download full-size image
5.
6.
7.
8.
Michael D. Jensen Ji?í Bajnárek Sang Yeoup Lee Soren Nielsen Christina Koutsari 《Journal of lipid research》2009,50(9):1863-1869
The relationship between overnight postabsorptive (fasting) respiratory exchange ratio (RER) and plasma FFA concentrations was addressed using data from three separate protocols, each of which involved careful control of the antecedent diet. Protocol 1 examined the relationship between fasting RER and the previous daytime RER. In Protocol 2 fasting, RER and plasma palmitate concentrations were measured in 29 women and 31 men (body mass index <30 kg·m−2). Protocol 3 analyzed data from Nielsen et al. (Nielsen, S., Z. K. Guo, J. B. Albu, S. Klein, P. C. O''Brien, M. D. Jensen. 2003. Energy expenditure, sex and endogenous fuel availability in humans. J. Clin. Invest. 111: 981-988.) to understand how fasting RER and palmitate concentrations relate within individuals during four consecutive measurements. The results were as follows: 1) Fasting RER was correlated (r = 0.74, P < 0.001) with the previous day''s average RER, and less so with RER variability. 2) Fasting RER was correlated (r = −0.39, P = 0.007) with fasting plasma palmitate concentrations. 3) The pattern of the RER/palmitate relationship was similar within individuals and between individuals; a negative slope was observed significantly more often than a positive slope (χ2 test; P < 0.001). Our findings suggest that, despite a fixed food quotient, the slight departures from energy equilibrium in a controlled General Clinical Research Center environment can effect plasma FFA concentrations. We suggest that including indirect calorimetry as part of FFA metabolism studies may aid in data interpretation. 相似文献
9.
10.
I C Kim 《The Journal of biological chemistry》1982,257(2):1063-1070
Rabbit antiserum produced against rat liver cytochrome H-450 was specific for cytochrome H-450. The antiserum did not react with hemolysate, microsomal and mitochondrial fractions of liver, and tissue extracts from heart, lung skeletal muscle, and testis of rat. With the monospecific antiserum, a rocket immunoelectrophoretic assay method was developed for the quantitation of the antigen with a sensitivity of 25 ng. By using rocket immunoelectrophoresis, the total amounts of the antigen found in liver, kidney, and brain of 20 rats were 33.6, 3.6, and 1.3 mg, respectively. It appears that the antigens in liver, kidney, and brain are immunologically identical. From immunological studies with subcellular fractions of rat liver, the antigen was found only in the postmicrosomal fraction. This indicates that the antigen is not a precursor or a proteolytic product of known cytochromes in mitochondria or microsomes. Therefore, cytochrome H-450 is a unique cytosolic protein found in brain, kidney, and liver. 相似文献