全文获取类型
收费全文 | 391篇 |
免费 | 45篇 |
专业分类
436篇 |
出版年
2021年 | 6篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 25篇 |
2014年 | 12篇 |
2013年 | 26篇 |
2012年 | 21篇 |
2011年 | 18篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 20篇 |
2006年 | 22篇 |
2005年 | 22篇 |
2004年 | 22篇 |
2003年 | 7篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 14篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1983年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1973年 | 2篇 |
1972年 | 5篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1969年 | 5篇 |
1968年 | 3篇 |
1964年 | 2篇 |
1962年 | 2篇 |
1955年 | 2篇 |
1954年 | 2篇 |
1950年 | 2篇 |
排序方式: 共有436条查询结果,搜索用时 15 毫秒
431.
D.J. Nolte 《Journal of insect physiology》1976,22(6):833-838
A new method of synthesis of the locust gregarization pheromone, locustol, is described, the pathway being from guaiacol to acetyl-isoacetovanillone, to isoacetovanillone, to 5-ethylguaiacol. These substances were all checked for their infrared spectra and were bioassayed. Only 5-ethylguaiacol affected chiasma frequency, hopper colour, and the morphometric ratio, although guaiacol had some effect on chiasma frequency. Hopper and adult faeces, as well as grasshopper faeces, were steamextracted, tested by infrared spectrophotometry and by gas chromatography, and were bioassayed. Only the hopper faeces extract contained the pheromone as well as some isoacetovanillone. In the adult and grasshopper faeces extracts no aromatic substance could be found but the impurities contained, possibly, a mixture of a secondary alcohol, a carboxylic acid, and/or its ester, some of which also occurred in the impure hopper faeces extract. Isovanillin, 5-methylguaiacol, and amylacetate were also bioassayed: they showed no effect on chiasma frequencies, but the latter stimulated the production of a gregaria ratio in solitaries. A figure is given of the chemical structures of eight substances which are part-analogues of locustol in regard to chiasma frequency, and of eight related substances which are chromosomally inactive but of which amylacetate stimulates the gregaria ratio and methylformate stimulates the production of black hopper colour in solitaries. A consideration of these structures may aid in solving the chemical action of locustol. 相似文献
432.
A novel hantavirus associated with an outbreak of fatal respiratory disease in the southwestern United States: evolutionary relationships to known hantaviruses. 总被引:13,自引:4,他引:9
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
B Hjelle S Jenison N Torrez-Martinez T Yamada K Nolte R Zumwalt K MacInnes G Myers 《Journal of virology》1994,68(2):592-596
Four Corners hantavirus (FCV) is the tentative name of the suspected etiologic agent of the newly identified hantavirus-associated respiratory distress syndrome (HARDS). The identification in HARDS patients of serum immunoglobulin M and immunoglobulin G antibodies that cross-reacted with Hantaan, Seoul, and Puumala virus antigens first suggested that FCV is a hantavirus. Limited nucleotide sequence data from the FCV glycoprotein-2 (G2) confirmed that FCV is a hantavirus and showed that it is most closely related to Prospect Hill and Puumala viruses. We have molecularly cloned approximately 95% of the sequences of the M and S segments of the FCV genome encoding the envelope glycoproteins and nucleocapsid protein N from the lungs of a patient with HARDS. The nucleotide sequence has been determined for 2,632 bases. The nucleotide sequence data show that FCV is a new member of the Puumala virus and Prospect Hill virus division of the hantavirus genus. Phylogenetic tree analyses indicate that the M and S segments have evolved in parallel. Therefore, the novel pathogenic activity of FCV is not likely to be the result of recent reassortment of segments from less pathogenic viruses. 相似文献
433.
Determination of volatile products of human colon cell line metabolism by GC/MS analysis 总被引:2,自引:0,他引:2
Dunja Zimmermann Michelle Hartmann Mary Pat Moyer Jürgen Nolte Jörg Ingo Baumbach 《Metabolomics : Official journal of the Metabolomic Society》2007,3(1):13-17
Colon cancer is one of the most reasons for cancer death worldwide. Thus, it is important to find new prognostic and diagnostic
marker, as well as to throw light on the special metabolic pathways of colon cancer cells. This paper highlights for the first
time some qualitative differences in the profiles of the volatile metabolites of colon cancer cell lines SW 480 (grade IV,
Duke B) and SW 1116 (grade II, Duke A) among themselves and in comparison to the normal colon cell line NCM460, which are
mostly represented by ketones and alcohols. These results, which were obtained by applying solid phase micro extraction (SPME)
and combined gas chromatography/mass spectrometry (GC/MS), are consistent with Warburg’s hypothesis because the found reaction
products may indicate that the cancer cells show the Crabtree’s effect. Furthermore, compounds like undecan-2-ol and pentadecan-2-one
were associated for the first time with the human metabolism. In summary, these findings indicate that the metabolism of colon
cancer cells differs extremely from the metabolism of healthy cells and it changes during the progress of the disease. Compounds
that are present in the breath, the blood and the tissue of patients represent the differences and they can serve as new biomarker
for colon cancer in future. 相似文献
434.
435.
436.
Bone allograft material is treated with sterilization methods to prevent the transmission of diseases from the donor to the recipient. The effect of some of these treatments on the integrity of the bone is unknown. This study was performed to evaluate the effect of several sterilization methods on the mechanical behaviour of human middle ear bones. Due to the size and composition of the bones (approximately 1.5 mm diameter by 4 mm long), mechanical testing options were limited to the traditional platens compression test. Experiments were first performed with synthetic bone to evaluate the precision of this test applied to small specimens. Following this, fresh frozen human ossicles were thawed and sterilized with (i) 1 N NaOH (n = 12); (ii) 0.9% LpH, a phenolic solution (n = 12); or (iii) steam at 134 degrees C (n = 18). A group of 26 control specimens did not receive any sterilization treatment. Material and structural properties were determined from axial compression testing. Results from the synthetic bone showed that the test was reproducible, with standard deviations less than 20% of the means. Significant differences occurred in stiffness and ultimate force values between NaOH-treated and autoclaved bones when compared to normals (p<0.05), but not for LpH-treated bones. LpH is not approved for medical use, so NaOH is the most appropriate of the treatments studied for the sterilization of ossicle allografts. 相似文献