全文获取类型
收费全文 | 971篇 |
免费 | 49篇 |
国内免费 | 1篇 |
出版年
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 26篇 |
2020年 | 12篇 |
2019年 | 22篇 |
2018年 | 32篇 |
2017年 | 25篇 |
2016年 | 36篇 |
2015年 | 48篇 |
2014年 | 70篇 |
2013年 | 68篇 |
2012年 | 89篇 |
2011年 | 86篇 |
2010年 | 60篇 |
2009年 | 36篇 |
2008年 | 38篇 |
2007年 | 56篇 |
2006年 | 38篇 |
2005年 | 32篇 |
2004年 | 32篇 |
2003年 | 30篇 |
2002年 | 25篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1994年 | 6篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1972年 | 4篇 |
1970年 | 1篇 |
1969年 | 3篇 |
1967年 | 2篇 |
1950年 | 1篇 |
排序方式: 共有1021条查询结果,搜索用时 15 毫秒
1.
Summary As a part of integrated study of makhana, the mineral contents of the plant parts and the fruits of makhana (Euryale ferox) have been presented here. It has been observed that the fruits were not only rich in minerals but also in protein. The plant
parts also contained high amounts of micronutrients. Its fruits are, therefore, a good supplement for minerals which are produced
from otherwise agriculturally waste (water-logged) areas. 相似文献
2.
Callus cultures were established from stem explants of Ruscus hypophyllum on a modified basal medium of Murashige and Skoog (1962) supplemented with 1 mg l-1 2,4-D+0.1 mg l-1 BAP. The optimal 2,4-D concentration for promoting shoot bud formation and growth was 0.05 mg l-1 along with 0.5 mg l-1 BAP. Sixty percent of rootless shoots produced flowers on the regenerating medium. Rooting was induced when shoots were transferred to half strength MS inorganic salts supplemented with 2 mg l-1 IBA. Eighty percent of plants transferred to soil have survived. 相似文献
3.
S Shimizu B Jha S Kagawa K Nakao K Yoshida S Wakabayashi A Matsuoka 《Endocrinologia japonica》1983,30(2):255-260
The culture for 7 days in medium with 5.5 mM glucose and 1 mM 2-deoxy-D-glucose enhanced the glucose sensitivity of neonatal rat B cells, and even stimulated their growth in vitro. Also, 2-deoxy-D-glucose supplementation maintained insulin release evoked by leucine and 2-ketoisocaproate from B cells at day 7 at levels several times higher than at day 1. The effect of leucine was greatly augmented by glutamine, whereas that of the 2-keto acid remained almost unchanged irrespective of the presence of glutamine. These results suggest an increase in oxidative catabolism of medium nutrients in B cells grown in medium with 2-deoxy-D-glucose for 7 days, and such metabolic changes may promote the growth of B cells in vitro. 相似文献
4.
The calcium binding characteristics of antibiotic X-537A (lasalocid-A) in a lipophilic solvent, acetonitrile (CH3CN), have been studied using circular dichroism (CD) spectroscopy. The analysis of the data indicated that in this medium polar solvent, X-537A forms predominantly the charged complexes of stoichiometries 2:1 and 1:1, the relative amounts of the two being dependent on [Ca2+]. The conformations of the complexes, arrived at on the basis of the data, seem to indicate a rigid part encompassing Ca2+, liganded to 3 oxygens of the molecule, viz., the carbonyl, the substituted tetrahydrofuran ring and the substituted pyran ring oxygens (apart from, possibly, the liganding provided by nitrogen atoms of the solvent molecules), and a flexible part consisting of the salicylic acid group of the molecule. 相似文献
5.
M A Swan R Vishwanath I G White P D Brown-Woodman 《Zeitschrift für mikroskopisch-anatomische Forschung》1990,104(2):273-286
Gossypol administered orally to male rats at a daily dose of 20 mg/kg body weight for 63 days caused hypertrophy of the cauda epididymal epithelium, with more than fourfold increase in height of the cells. The principal cells lost most of their microvilli and formed apical blebs which appeared to produce the dense secretory material which was found in the lumen. Less dramatic but similar changes also occurred after 9 days on the same regimen, with the height of the epithelium doubling. However after 19 days on this regimen, with the height of the epithelium doubling. However after 19 days on this regimen, the epithelium looked fairly normal apart from a maintained hypertrophy. As reported in other studies, the cauda epididymal sperm were severely damaged and immotile; many were decapitated and the oxygen uptake was low. Ultrastructural defects were abnormal or absent mitochondria, absence of plasma membranes and axonemal components and accessory fibres. 相似文献
6.
Summary Protoplasts were isolated for the first time from cell suspensions ofNigella sativa. These were then cultured in media and observed at regular intervals. Different concentrations of auxin and kinetin were tried with success to obtain root from the callus tissues of the protoplasts. 相似文献
7.
A series of coal mine spoils (5, 10, 12, 16 and 20-yr old) in a dry tropical environment was sampled to assess the changes with time in spoil characteristics, species composition and plant biomass. Coarse fragments (>2 mm) decreased with age of mine spoil while the proportion of 0.2–0.1 mm particles increased. Total soil N, mineral N, NaHCO3-extractable Pi, and exchangeable K increased with age of mine spoil and these parameters were lower in mine spoils than native forest soil even after 20 years of succession. Exchangeable Na decreased with age of mine spoil and in 20-yr old spoil it was higher than native forest soil. Plant community composition changed with age. Only a few species participated in community formation. Species richness increased with age, while evenness and species diversity declined from 5-yr old to 16-yr old community with an increase in the 20-yr old community. A reverse trend occurred for concentration of dominance. Area-weighted shoot and root biomass of other species increased with the age of the mine spoil while that of Xanthium strumarium patches declined with age. Data collected on spoil features, microbial C, N and P, and shoot and root biomass when subjected to Discriminant Analysis indicated a continued profound effect of age. 10 and 12-yr old mine spoils were closer to each other, and 5 and 20-yr old spoils were farthest apart. 相似文献
8.
Jha Anubhuti Kumar Anil Kumar Awanish 《International journal of peptide research and therapeutics》2020,26(3):1559-1566
International Journal of Peptide Research and Therapeutics - Candida albicans is the most common nosocomial systemic fungal infections causing high mortality/morbidity. Existing antifungal... 相似文献
9.
ObjectiveIn health-care systems, compression is an essential tool to solve the storage and transmission problems. In this regard, this paper reports a new electrocardiogram (ECG) data compression scheme which employs sifting function based empirical mode decomposition (EMD) and discrete wavelet transform.MethodEMD based on sifting function is utilized to get the first intrinsic mode function (IMF). After EMD, the first IMF and four significant sifting functions are combined together. This combination is free from many irrelevant components of the signal. Discrete wavelet transform (DWT) with mother wavelet ‘bior4.4’ is applied to this combination. The transform coefficients obtained after DWT are passed through dead-zone quantization. It discards small transform coefficients lying around zero. Further, integer conversion of coefficients and run-length encoding are utilized to achieve a compressed form of ECG data.ResultsCompression performance of the proposed scheme is evaluated using 48 ECG records of the MIT-BIH arrhythmia database. In the comparison of compression results, it is observed that the proposed method exhibits better performance than many recent ECG compressors. A mean opinion score test is also conducted to evaluate the true quality of the reconstructed ECG signals.ConclusionThe proposed scheme offers better compression performance with preserving the key features of the signal very well. 相似文献
10.
Raju V. Kumar M. Yariswamy Vikram Joshi K.K. Dharmappa Shivaprasad H. Venkatesha B.K. Sharath Bannikuppe S. Vishwanath 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2013,164(2):111-116
In the present study we describe the purification and characterization of Malabarase, a serine protease from Trimeresurus malabaricus venom. Purification was achieved by gel-permeation chromatography on Sephadex G-75 followed by ion-exchange chromatography on CM Sephadex C-25. Homogeneity of Malabarase was confirmed by RP-HPLC. Malabarase is a monomer that migrated as a single protein band on SDS-PAGE under both reducing and non-reducing conditions. The molecular mass of Malabarase was determined to be 23.4 kDa using MALDI-TOF mass spectrometry. Malabarase is the first serine protease purified from T. malabaricus venom and is selective for fibrinogen. Malabarase hydrolyzes Aα and Bβ but not γ-chains of fibrinogen similar to the metalloproteases, Malabarin and Trimarin, isolated from the same venom. However, the action of Malabarase on plasma coagulation is opposite than those of Malabarin, Trimarin and the whole venom. Malabarase significantly prolonged plasma coagulation time from 152–341 s; whereas Malabarin, Trimarin, and whole venom, greatly reduce plasma clotting time from 152 to 12, 48, and 14 s, respectively. Malabarase did not show hemorrhagic or myotoxic activity. In contrast, Malabarin, Trimarin and whole venom are highly hemorrhagic and myotoxic. These observations support the specificity of Malabarase towards fibrinogen and its non-toxic nature. In conclusion, Malabarase is a fibrinogen-specific, anti-coagulant, and non-toxic serine protease. Its selective action and non-toxic nature might make it useful for treating thrombotic disorders. 相似文献