全文获取类型
收费全文 | 1109篇 |
免费 | 73篇 |
专业分类
1182篇 |
出版年
2023年 | 8篇 |
2022年 | 27篇 |
2021年 | 61篇 |
2020年 | 27篇 |
2019年 | 18篇 |
2018年 | 39篇 |
2017年 | 30篇 |
2016年 | 31篇 |
2015年 | 41篇 |
2014年 | 56篇 |
2013年 | 75篇 |
2012年 | 100篇 |
2011年 | 77篇 |
2010年 | 45篇 |
2009年 | 31篇 |
2008年 | 47篇 |
2007年 | 42篇 |
2006年 | 34篇 |
2005年 | 35篇 |
2004年 | 18篇 |
2003年 | 14篇 |
2002年 | 16篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 14篇 |
1995年 | 5篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1980年 | 7篇 |
1979年 | 14篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 11篇 |
1972年 | 11篇 |
1971年 | 8篇 |
1970年 | 6篇 |
1966年 | 6篇 |
排序方式: 共有1182条查询结果,搜索用时 15 毫秒
91.
Patil Prasanna Kumar Vinay Tharabenahalli Nagaraju Ghate Sudeep Darbhe Baskaran Viswanathan Avunje Satheesha 《Antonie van Leeuwenhoek》2021,114(12):2019-2031
Antonie van Leeuwenhoek - The endemic Indian white shrimp (Penaeus indicus) is an economically important crustacean species, distributed in the Indo-West Pacific region. Knowledge of its gut... 相似文献
92.
93.
Wei Chen Shaozhen He Degao Liu Gunvant B. Patil Hong Zhai Feibing Wang Troy J. Stephenson Yannan Wang Bing Wang Babu Valliyodan Henry T. Nguyen Qingchang Liu 《PloS one》2015,10(9)
Sweetpotato highly produces carotenoids in storage roots. In this study, a cDNA encoding geranylgeranyl phyrophosphate synthase (GGPS), named IbGGPS, was isolated from sweetpotato storage roots. Green fluorescent protein (GFP) was fused to the C-terminus of IbGGPS to obtain an IbGGPS-GFP fusion protein that was transiently expressed in both epidermal cells of onion and leaves of tobacco. Confocal microscopic analysis determined that the IbGGPS-GFP protein was localized to specific areas of the plasma membrane of onion and chloroplasts in tobacco leaves. The coding region of IbGGPS was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis thaliana to obtain transgenic plants. High performance liquid chromatography (HPLC) analysis showed a significant increase of total carotenoids in transgenic plants. The seeds of transgenic and wild-type plants were germinated on an agar medium supplemented with polyethylene glycol (PEG). Transgenic seedlings grew significantly longer roots than wild-type ones did. Further enzymatic analysis showed an increased activity of superoxide dismutase (SOD) in transgenic seedlings. In addition, the level of malondialdehyde (MDA) was reduced in transgenics. qRT-PCR analysis showed altered expressions of several genes involved in the carotenoid biosynthesis in transgenic plants. These data results indicate that IbGGPS is involved in the biosynthesis of carotenoids in sweetpotato storage roots and likely associated with tolerance to osmotic stress. 相似文献
94.
Pravin Patil Surendra Kumar Malik Shrikant Sutar Shrirang Yadav Joseph John Kangila Venkataraman Bhat 《Nordic Journal of Botany》2015,33(6):696-707
Seed morphology of Abelmoschus is known to be variable, but patterns of variation have never been critically studied. We studied seed macro‐ and micro‐morphological characters, including seed shape/size, seed coat pattern and trichome density/structure in multiple samples to evaluate the taxonomic significance of seed characters. Among the studied characters, seed shape and trichome structure were found to have major taxonomic importance and proved to be valuable characters for separating taxa. Two main seed types were present: seeds with deciduous trichomes and seeds with persistent trichomes. These characters offer significant evidence to the distinctness of certain species (A. esculentus, A. moschatus subsp. moschatus, A. moschatus subsp. tuberosus, A. crinitus and A. angulosus). Further, our results indicate that A. moschatus subsp. tuberosus should be maintained as a separate subspecies while A. manihot subsp. tetraphyllus var. pungens may be merged in A. angulosus. No significant intraspecific variation was observed, except in A. esculentus. We conclude that seed coat sculpturing and seed trichomes do indeed provide stable and diagnostic characters for many morphologically closely related taxa of Abelmoschus and that LM/SEM techniques can be useful in solving systematic problems and management of Abelmoschus genetic resources. 相似文献
95.
Kalagouda B. Gudasi Siddappa A. Patil Rashmi V. Shenoy Sim Wan Annie Bligh 《Inorganica chimica acta》2006,359(10):3229-3236
The chelating behavior of 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) (H2dapa) towards manganese(II), cadmium(II) and oxovanadium(IV) ions has been studied by elemental analyses, conductance measurements, magnetic properties and spectral (IR, 1H NMR, UV-Vis and EPR) studies. The IR spectral studies suggest the pentadentate nature of the ligand with pyridine nitrogen, two azomethine nitrogens and two carbonyl oxygen atoms as the ligating sites. Six coordinate structure for [VO(H2dapa)]SO4 · H2O and seven coordinate structures for [Mn(H2dapa)(Cl)(H2O)]Cl · 2H2O and [Cd(H2dapa)Cl2] · H2O complexes have been proposed. Pentagonal bipyramidal geometry for [Mn(H2dapa)(Cl)(H2O)]Cl · 2H2O and [Cd(H2dapa)(Cl2)] · H2O complexes was confirmed by single crystal analysis. The X-band EPR spectra of the oxovanadium(IV) and manganese(II) complexes in the polycrystalline state at room (300 K) and also at liquid nitrogen temperature (77 K) were recorded and their salient features are reported. 相似文献
96.
PSGL-1 derived from human neutrophils is a high-efficiency ligand for endothelium-expressed E-selectin under flow 总被引:1,自引:0,他引:1
Zou X Shinde Patil VR Dagia NM Smith LA Wargo MJ Interliggi KA Lloyd CM Tees DF Walcheck B Lawrence MB Goetz DJ 《American journal of physiology. Cell physiology》2005,289(2):C415-C424
P-selectin glycoprotein ligand-1 (PSGL-1) has been proposed as an important tethering ligand for E-selectin and is expressed at a modest level on human leukocytes. Sialyl Lewis x (sLex)-like glycans bind to E-selectin and are expressed at a relatively high level on circulating leukocytes. It is unclear whether PSGL-1 has unique biochemical attributes that contribute to its role as an E-selectin ligand. To probe this issue, we conjugated microspheres with either sLex or PSGL-1 purified from myeloid cells (neutrophils and HL-60) and compared their adhesion to endothelial expressed E-selectin under defined shear conditions. We found that both sLex and PSGL-1 microspheres adhere to 4 h of IL-1-activated human umbilical vein endothelial cells predominantly through E-selectin. Analysis of the adhesion revealed that the rate of initial tethering of the PSGL-1 microspheres to E-selectin was significantly greater than the rate of initial tethering of the sLex microspheres despite the fact that the sLex microspheres tested had higher ligand densities than the PSGL-1 microspheres. We also found that pretreatment of the PSGL-1 or sLex microspheres with HECA-452 had no significant effect on initial tethering to E-selectin. These results support the hypotheses that 1) PSGL-1 is a high-efficiency tethering ligand for E-selectin, 2) ligand biochemistry can significantly influence initial tethering to E-selectin, and 3) PSGL-1 tethering to E-selectin can occur via non-HECA-452 reactive epitopes. adhesion; leukocyte; inflammation 相似文献
97.
A highly chitinolytic strain Penicillium ochrochloron MTCC 517 was procured from MTCC, Chandigarh, India. Culture medium supplemented with 1% chitin was found to be suitable for maximum production of chitinase. Purification of extracellular chitinase was done from the culture medium by organic solvent precipitation and DEAE-cellulose column chromatography. The chitinase was purified 6.92-fold with 29.9% yield. Molecular mass of purified chitinase was found to be 64 kDa by SDS-PAGE. The chitinase showed optimum temperature 40 °C and pH 7.0. The enzyme activity was completely inhibited by Hg2+, Zn2+, K+ and NH4+. The enzyme kinetic study of purified chitinase revealed the following characteristics, such as apparent Km 1.3 mg ml?1, Vmax 5.523 × 10?5 moles l?1 min?1 and Kcat 2.37 s?1 and catalytic efficiency 1.82 s?1 M?1. The enzyme hydrolyzed colloidal chitin, glycol chitin, chitosan, glycol chitosan, N,N′-diacetylchitobiose, p-nitrophenyl N-acetyl-β-d-glucosaminide and 4-methylumbelliferyl N-acetyl-β-d-glucosaminide. The chitinase of P. ochrochloron MTCC 517 is an exoenzyme, which gives N-acetylglucosamine as the main hydrolyzate after hydrolysis of colloidal chitin. Protoplasts with high regeneration capacity were obtained from Aspergillus niger using chitinase from P. ochrochloron MTCC 517. Since it also showed antifungal activity, P. ochrochloron MTCC 517 seems to be a promising biocontrol agent. 相似文献
98.
Kusal K. Das Amrita Das Gupta Salim A. Dhundasi Ashok M. Patil Swastika N. Das Jeevan G. Ambekar 《Biometals》2007,20(2):177-184
In this experimental study, we investigated whether l-ascorbic acid has any influence on the blood antioxidant defense system, lipid peroxidation and hematological parameters
of the albino rats exposed to nickel sulfate(NiSO4).Twenty four adult rats were divided into four groups of six animals in each group. The control rats were untreated and comprised
Group I. Group II rats were administered nickel sulfate (2.0 mg/100 g b.wt.; intraperitonially, i.p.). Group II rats were
treated orally l-ascorbic acid (50 mg/100 g b.wt.) and Group IV rats were given both nickel sulfate and l-ascorbic acid simultaneously on alternate days until the tenth dose. The hematological parameters were assessed: red blood
corpuscle counts, packed cell volume %, hemoglobin concentration, white blood corpuscle counts and platelets count decreased
significantly and clotting time increased significantly in nickel treated rats. We also observed increase malondialdehyde
(MDA) and decrease glutathione level (GSH) in erythrocytes of nickel treated rats. The activities of erythrocyte antioxidant
enzymes like superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were significantly increased in
rats treated with nickel sulfate. Simultaneously treatment of l-ascorbic acid exhibited a possible protective role on the toxic effect of nickel sulfate on the hematological values, erythrocyte
MDA and GSH concentrations as well as antioxidant enzymatic defense system. 相似文献
99.
100.
Abhrak bhasma is a commonly used ayurvedic drug against many diseases including hepatitis. It is tested in albino rats using a model of hepatitis induced by a single dose of CCl4 (3 ml/kg body wt). Different doses of abhrak bhasma (10, 20, 30 and 40 mg/kg body wt) were tested to decide the dose related hepatoprotective efficacy. The centrolobular necrosis induced by single dose of CCl4 was reduced significantly by abhrak bhasma (10 mg) and liver histology was also protected by 20 mg dose. Liver acid lipase activity was lowered, while alkaline and lipoprotein lipase activities were elevated due to treatment of single dose of CCl4. Abhrak bhasma counteracted the action of CCl4 on liver lipolytic enzymes. CCl4 did not alter the kidney histologically. Activities of three lipases of rat kidney (acid, alkaline and lipoprotein lipases) were reduced by CCl4 treatment and were reversed by administration of abhrak bhasma. Acid lipase activity of rat adipose tissue was reduced by CCl4 treatment. On the contrary alkaline, lipoprotein and hormone sensitive lipases were enhanced after 24 hr of administration of CCl4. Acid lipase activity was raised by administration of different doses of abhrak bhasma concurrent with CCl4. Abhrak bhasma treatment along with CCl4 enhanced alkaline lipase activity at 10 and 20 mg dose and later it was reduced at 30 and 40 mg doses and came to normal levels. Lipoprotein and hormone sensitive lipases were reduced by the counteraction of increasing doses of abhrak bhasma. 相似文献