全文获取类型
收费全文 | 14235篇 |
免费 | 369篇 |
国内免费 | 7篇 |
出版年
2021年 | 98篇 |
2020年 | 100篇 |
2019年 | 104篇 |
2018年 | 306篇 |
2017年 | 271篇 |
2016年 | 345篇 |
2015年 | 354篇 |
2014年 | 422篇 |
2013年 | 619篇 |
2012年 | 561篇 |
2011年 | 610篇 |
2010年 | 388篇 |
2009年 | 278篇 |
2008年 | 384篇 |
2007年 | 421篇 |
2006年 | 393篇 |
2005年 | 388篇 |
2004年 | 330篇 |
2003年 | 364篇 |
2002年 | 337篇 |
2001年 | 317篇 |
2000年 | 273篇 |
1999年 | 214篇 |
1998年 | 106篇 |
1992年 | 269篇 |
1991年 | 265篇 |
1990年 | 208篇 |
1989年 | 239篇 |
1988年 | 276篇 |
1987年 | 281篇 |
1986年 | 262篇 |
1985年 | 284篇 |
1984年 | 233篇 |
1983年 | 185篇 |
1982年 | 101篇 |
1979年 | 259篇 |
1978年 | 188篇 |
1977年 | 166篇 |
1976年 | 168篇 |
1975年 | 196篇 |
1974年 | 293篇 |
1973年 | 284篇 |
1972年 | 272篇 |
1971年 | 267篇 |
1970年 | 274篇 |
1969年 | 264篇 |
1968年 | 200篇 |
1967年 | 205篇 |
1966年 | 179篇 |
1965年 | 131篇 |
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
1.
2.
3.
4.
A new simple enzymatic method for measuring AMP content in freeze-clamped rat heart is presented. The method is based on the ammonia estimation after the deamination of 5'-AMP by muscle 5'-adenylic acid deaminase. The minimum detectable amount of AMP was about 1.5 nmol. The recovery of AMP added to the tissue homogenate was 94%. The variance coefficient evaluated by assaying five samples from one tissue extract was equal to 5%. AMP content of rat heart (0.28 mumol/g wet tissue) is comparable with the values reported by others. 相似文献
5.
6.
Pfarrer Ch. Münch 《Plant Systematics and Evolution》1862,12(2):35-37
Ohne Zusammenfassung 相似文献
7.
8.
Bacopa monniera Wettst. (BM, syn. Herpestis monniera L; Scrophulariaceae), is an Ayurvedic drug used as a rasayana. Its fresh juice was earlier reported to have significant antiulcerogenic activity. In continuation, methanolic extract of BM (BME) standardized to bacoside-A content (percentage-38.0 ± 0.9), when given in the dose of 10–50 mg/kg, twice daily for 5 days, showed dose-dependent anti-ulcerogenic on various gastric ulcer models induced by ethanol, aspirin, 2 h cold restraint stress and 4 h pylorus ligation. BME in the dose of 20 mg/kg, given for 10 days, twice daily showed healing effects against 50% acetic acid-induced gastric ulcers. Further work was done to investigate the possible mechanisms of its action by studying its effect on various mucosal offensive acid-pepsin secretion and defensive factors like mucin secretion, mucosal cell shedding, cell proliferation and antioxidant activity in rats. BME 20 mg/kg showed no effect on acid-pepsin secretion, increased mucin secretion, while it decreased cell shedding with no effect on cell proliferation. BME showed significant antioxidant effect per se and in stressed animals. Thus, the gastric prophylactic and curative effects of BME may be due to its predominant effect on mucosal defensive factors. 相似文献
9.
10.
M. Filek J. Biesaga-Kościelniak I. Marcińska M. Cvikrová I. Macháčková J. Krekule 《Biologia Plantarum》2010,54(3):483-487
The contents of endogenous free and conjugated polyamines, putrescine (Put) and spermidine (Spd), were determined during 9
week of vernalization (at 5 °C) in winter wheat seedlings cultivated on Murashige and Skoog media without (MS0) and with 2
mg dm−3 zearalenone (MSZEN). At the 4th week of chilling treatment, which is sufficient to induce generative development in 30 % of plants, the marked increase in
free and conjugated forms of Put and free Spd were observed. The presence of ZEN in medium significantly accelerated the vernalization.
About 20 % of plants treated with ZEN flowered already after 2 weeks and 40 % after 3 weeks of chilling. Significantly higher
content of free Put was determined in roots grown on MSZEN compared with MS0 during the first 5 weeks of vernalization with
maximum at the 4th week. After germination, a marked decrease in free Spd content was observed both in plants grown on MS0 and MSZEN. Application
of ZEN significantly slowed down the Spd decline in leaves and roots during the first and second week of vernalization. The
content of Spd and its conjugates decreased in vernalized plants after 1 week of cultivation at 20 °C. 相似文献