全文获取类型
收费全文 | 862篇 |
免费 | 62篇 |
国内免费 | 1篇 |
专业分类
925篇 |
出版年
2022年 | 5篇 |
2021年 | 7篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2016年 | 18篇 |
2015年 | 28篇 |
2014年 | 24篇 |
2013年 | 40篇 |
2012年 | 48篇 |
2011年 | 49篇 |
2010年 | 38篇 |
2009年 | 29篇 |
2008年 | 55篇 |
2007年 | 37篇 |
2006年 | 46篇 |
2005年 | 54篇 |
2004年 | 38篇 |
2003年 | 29篇 |
2002年 | 34篇 |
2001年 | 11篇 |
1999年 | 12篇 |
1998年 | 21篇 |
1997年 | 9篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 16篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1974年 | 8篇 |
1973年 | 5篇 |
1970年 | 6篇 |
1969年 | 9篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1963年 | 4篇 |
1961年 | 5篇 |
排序方式: 共有925条查询结果,搜索用时 0 毫秒
891.
Helga Kühne 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1950,20(7-8):226-253
Ohne ZusammenfassungMit 24 TextabbildungenDissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Hamburg. 相似文献
892.
The different secretions of the mouth, the vestibular organs, and the vestibular pits of chaetognaths are shown on scanning
electron micrographs of the head ofSagitta setosa. The secreting organs are described and the functions of the secretions are discussed. In addition, the secretion under the
praeputium, a pit between the two rows of anterior teeth, and the surface structure of the teeth are described. 相似文献
893.
Summary Puffer fish (Tetraodon steindachneri) can execute precise maneuvers due to their highly specialized mode of propulsion. In the conventional locomotion exemplified by the goldfish (Carassius auratus), the fish thrusts are generated by lateral beating of the caudal fin. In contrast, the puffer generates its propulsive force by very rapid undulating movements of the pectoral, dorsal and anal fins. The fine structure of the fin muscles is identical in the two species of fishes, despite the differences in fin movement; cytologically, the fibers are intermediate between those of red and of white muscle. On the other hand, both the fusion frequency and the number of motor endplates are considerably higher in the fin muscles of the puffer than in those of the goldfish. 相似文献
894.
895.
896.
Tom J. Mabry Imre J. Eifert Christina Chang Helga Mabry Carol Kido H.-Diermar. Behnke 《Biochemical Systematics and Ecology》1975,3(1):53-54
The discovery of anthocyanins (and no betalains) along with S-type sieve-element plastids in Theligonum cynocrambe supports the exclusion of this taxon from the order Centrospermae. 相似文献
897.
Ingrid Beck-Speier Helga Hinze Helmut Holzer 《Biochimica et Biophysica Acta (BBA)/General Subjects》1985,841(1):81-89
Mammalian tissues show significant differences in the activity of sulfite oxidase (EC 1.8.3.1) which detoxifies sulfite by oxidation to sulfate. Lung tissue and phagocytic cells such as alveolar macrophages, peritoneal macrophages, Kupffer cells and granulocytes show very low activities of sulfite oxidase. Liver tissue and hepatocytes, however, exhibit high activities of sulfite oxidase. Lung tissue and macrophages show an almost 100% decrease of the intracellular ATP levels when incubated with 1 mM sulfite at pH 6 for 30 min. In addition, the O2 consumption of lung tissue is inhibited by 1 mM sulfite at pH 6 by more than 80%. This sulfite-induced decrease of the ATP level and of the O2 consumption of lung tissue is enhanced between pH 6.0 and pH 7.4 with decreasing pH value of the incubation medium. In contrast, the ATP levels in liver tissue and hepatocytes are not affected by 1 mM sulfite at pH 6. The O2 consumption of liver tissue and hepatocytes is significantly increased by sulfite due to the high activities of sulfite oxidase. Therefore, the activity of the ‘sulfite-detoxifying enzyme’ sulfite oxidase and the sensitivity of the energy metabolism to sulfite show a reciprocal relationship in the tissues and cells studied. 相似文献
898.
Helga I. Maass 《Plant Systematics and Evolution》1997,208(1-2):35-44
Polymorphisms for six enzyme systems (GPI, IDH, PDG, PGM, SKD, and TPI) were analysed in the top onion,Allium ×proliferum. Five multilocus isozyme genotypes were found. The banding patterns of top onions were compared with those ofA. ×wakegi, A. cepa, A. fistulosum, A. altaicum, and artificial hybrids between these three species. One top onion type and one artificial hybrid had identical banding patterns. Shallots andA. altaicum, the wild progenitor ofA. fistulosum, cannot be distinguished from the common onion andA. fistulosum, respectively; these species are also potential contributors to the top onion's gene pool. 相似文献
899.
900.
Amany K. Elshorbagy Helga Refsum A. David Smith Ian M. Graham 《Obesity (Silver Spring, Md.)》2009,17(7):1435-1440
We recently reported a strong positive association of plasma total cysteine (tCys) with fat mass in over 5,000 subjects. As γ‐glutamyltransferase (GGT) enzyme increases cysteine availability by catalyzing glutathione breakdown and is positively associated with BMI and adiposity, we hypothesized that GGT might explain the association of tCys with adiposity. To study whether the associations of tCys and serum GGT with BMI and obesity were interrelated we conducted a cross‐sectional study using data from 1,550 subjects recruited from nine European countries in the COMAC project. Multiple linear and logistic regression models and concentration‐response curves were used. In age and sex‐adjusted analyses, tCys showed strong positive associations with BMI (partial r = 0.19, P < 0.001), and obesity (odds ratio (OR) for 4th vs. 1st tCys quartile: 2.8; 95% confidence interval: 1.6–5.0, P < 0.001), both of which remained robust after adjustment for GGT and other metabolic and lifestyle confounders. Serum GGT was also a positive predictor of BMI (partial r = 0.17, P < 0.001) and obesity (OR for 4th vs. 1st GGT quartile: 4.8; 95% confidence interval: 2.5–9.2, P < 0.001), independent of tCys. However, the associations of GGT with BMI and obesity were weakened by adjustment for obesity‐related factors such as serum lipids and blood pressure. These results indicate that tCys is a strong positive predictor of BMI and obesity, independent of GGT and other obesity‐related factors. We also suggest that the association of serum GGT with BMI and obesity is unrelated to the role of GGT in cysteine turnover. The potential link between cysteine and fat metabolism should be further evaluated. 相似文献