全文获取类型
收费全文 | 1748篇 |
免费 | 97篇 |
国内免费 | 4篇 |
专业分类
1849篇 |
出版年
2024年 | 6篇 |
2023年 | 14篇 |
2022年 | 56篇 |
2021年 | 77篇 |
2020年 | 36篇 |
2019年 | 48篇 |
2018年 | 58篇 |
2017年 | 56篇 |
2016年 | 71篇 |
2015年 | 98篇 |
2014年 | 115篇 |
2013年 | 130篇 |
2012年 | 168篇 |
2011年 | 161篇 |
2010年 | 85篇 |
2009年 | 65篇 |
2008年 | 94篇 |
2007年 | 64篇 |
2006年 | 67篇 |
2005年 | 63篇 |
2004年 | 49篇 |
2003年 | 44篇 |
2002年 | 30篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1986年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1967年 | 3篇 |
排序方式: 共有1849条查询结果,搜索用时 0 毫秒
31.
Syed Siraj-ul-Islam Chintala V.N. Rao Atindra N. Chakraborty S. Ghosh Dastidar 《Carbohydrate research》1982,110(1):69-75
The lipopolysaccharide isolated from the cells of Shigella boydii type 8 bacteria gave precipitin bands against homologous antisera on Ouchterlony plates, whereas the carbohydrate-containing fractions obtained from it did not. One of the fractions was obtained in major proportion and contained 23.5% of sugars. A structure was assigned to the carbohydrate chain in this material by using the results of methylation, periodate oxidation, and deamination studies. 相似文献
32.
In this paper, a fractional complex transform (FCT) is used to convert the given fractional partial differential equations (FPDEs) into corresponding partial differential equations (PDEs) and subsequently Reduced Differential Transform Method (RDTM) is applied on the transformed system of linear and nonlinear time-fractional PDEs. The results so obtained are re-stated by making use of inverse transformation which yields it in terms of original variables. It is observed that the proposed algorithm is highly efficient and appropriate for fractional PDEs and hence can be extended to other complex problems of diversified nonlinear nature. 相似文献
33.
Mohyeddin Mandana Bonab Kamran Alimoghaddam Fatemeh Talebian Syed Hamid Ghaffari Ardeshir Ghavamzadeh Behrouz Nikbin 《BMC cell biology》2006,7(1):14-7
Background
A hot new topic in medical treatment is the use of mesenchymal stem cells (MSC) in therapy. The low frequency of this subpopulation of stem cells in bone marrow (BM) necessitates their in vitro expansion prior to clinical use. We evaluated the effect of long term culture on the senescence of these cells. 相似文献34.
Syed Mohsin Waheed Arnab Ghosh Ritu Chakravarti Ashis Biswas Mohammad Mahfuzul Haque Koustubh Panda Dennis J. Stuehr 《Free radical biology & medicine》2010,48(11):1548-1558
Although the insertion of heme into proteins enables their function in bioenergetics, metabolism, and signaling, the mechanisms and regulation of this process are not fully understood. We developed a means to study cellular heme insertion into apo-protein targets over a 3-h period and then investigated how nitric oxide (NO) released from a chemical donor (NOC-18) might influence heme (protoporphyrin IX) insertion into seven targets that present a range of protein structures, heme ligation states, and functions (three NO synthases, two cytochrome P450's, catalase, and hemoglobin). NO blocked cellular heme insertion into all seven apo-protein targets. The inhibition occurred at relatively low (nM/min) fluxes of NO, was reversible, and did not involve changes in intracellular heme levels, activation of guanylate cyclase, or inhibition of mitochondrial ATP production. These aspects and the range of protein targets suggest that NO can act as a global inhibitor of heme insertion, possibly by inhibiting a common step in the process. 相似文献
35.
36.
Syed Muhammad Hamid Mevlut Citir Erdem Murat Terzi Ismail Cimen Zehra Yildirim Asli Ekin Dogan Begum Kocaturk Umut Inci Onat Moshe Arditi Christian Weber Alexis TraynorKaplan Carsten Schultz Ebru Erbay 《EMBO reports》2020,21(12)
The ER‐bound kinase/endoribonuclease (RNase), inositol‐requiring enzyme‐1 (IRE1), regulates the phylogenetically most conserved arm of the unfolded protein response (UPR). However, the complex biology and pathology regulated by mammalian IRE1 cannot be fully explained by IRE1’s one known, specific RNA target, X box‐binding protein‐1 (XBP1) or the RNA substrates of IRE1‐dependent RNA degradation (RIDD) activity. Investigating other specific substrates of IRE1 kinase and RNase activities may illuminate how it performs these diverse functions in mammalian cells. We report that macrophage IRE1 plays an unprecedented role in regulating phosphatidylinositide‐derived signaling lipid metabolites and has profound impact on the downstream signaling mediated by the mammalian target of rapamycin (mTOR). This cross‐talk between UPR and mTOR pathways occurs through the unconventional maturation of microRNA (miR) 2137 by IRE1’s RNase activity. Furthermore, phosphatidylinositol (3,4,5) phosphate (PI(3,4,5)P3) 5‐phosphatase‐2 (INPPL1) is a direct target of miR‐2137, which controls PI(3,4,5)P3 levels in macrophages. The modulation of cellular PI(3,4,5)P3/PIP2 ratio and anabolic mTOR signaling by the IRE1‐induced miR‐2137 demonstrates how the ER can provide a critical input into cell growth decisions. 相似文献
37.
Syed Husne Mobarak Anamika Koner Saubhik Mitra Paroma Mitra Anandamay Barik 《Journal of Applied Entomology》2020,144(7):616-631
Green gram, Vigna radiata (L.) Wilczek, is an important pulse crop of Asia. Severe attack by the larvae of Spilosoma obliqua Walker (Lepidoptera: Arctiidae) causes defoliation of green gram and reduces seed yield. Females lay eggs on the leaf surface, and therefore, surface wax plays an important role as short-range attractant and oviposition stimulant. So, we have attempted to find out whether leaf surface wax compounds (alkanes and free fatty acids) from three green gram cultivars (PDM 54, PUSA BAISAKHI and SAMRAT) could act as short-range attractant and oviposition stimulant in females. The TLC, GC-MS and GC-FID analyses of n-hexane extracts revealed 20 n-alkanes from n-C15 to n-C36 and 13 free fatty acids from C12:0 to C21:0, whilst linoleic acid was unique in SAMRAT. Pentacosane was the predominant amongst n-alkanes in the leaf surface waxes of three cultivars. Heneicosanoic acid and palmitoleic acid were the predominant free fatty acids in the leaf surface waxes of PDM 54, and PUSA BAISAKHI and SAMRAT, respectively. Females were attracted towards one leaf equivalent surface wax of three green gram cultivars against solvent controls (n-hexane) in Y-tube olfactometer bioassays. A synthetic blend of pentacosane, heptacosane, nonacosane, hexatriacontane, palmitoleic acid, linolenic acid and stearic acid, a synthetic blend of pentacosane, hexatriacontane and stearic acid, and a synthetic blend of hexatriacontane, linolenic acid and stearic acid resembling in amounts present in one leaf equivalent surface wax of PDM 54, PUSA BAISAKHI and SAMRAT, respectively, served as short-range attractant and oviposition stimulant in females. Females showed equal preference for egg laying towards the above three synthetic blends when these blends were tested against each other, and hence, these blends could be employed in development of baited traps in pest management strategies. 相似文献
38.
39.
Hina Gul Muhammad Awais Salina Saddick Yazeed Ahmed Falak Sher Khan Eilaf Ahmed Umara Afzal Syed Muhammad Zaigham Abbas Naqvi Muhammad Asghar Khan Muhammad Gulfraz Ghazala Kaukab Raja 《Saudi Journal of Biological Sciences》2021,28(1):247-254
Liver disorders may occur as a result of exposure to chemical compounds capable of inducing the oxidative stress and hepatic injuries. The aim of present study was to investigate the effects of flower extracts of B. Variegata for the treatment of liver injury induced by the CCl4. About 1 ml/kg body weight (b.w) of CCl4 was induced to experimental mice by intraperitoneal way for 14 days. The methanol and chloroform extracts (100, 200 and 300 mg/kg b.w) were administered to experimental animals for 14 days along with standard drug Silymarine (100 mg/kg b.w). The extracts alone showed no evidence of hepatic toxicity but animals exposed to CCl4 without the treatment with B. Variegata presented variations in levels of liver enzymes, antioxidant enzymes, proteins and blood cells as well as injuries in liver cells were also observed during histopathological study. However, after the treatments especially with 300 mg/kg b.w of methanol flower extracts levels of liver markers (ALT, AST and ALP), antioxidant enzymes and blood cells decreases and turned towards normal levels. Whereas level of total proteins and bilirubin was improved and damaged liver cells were repaired. The curative activity of flower extracts can be correlated to the higher potential of antioxidants and occurrence of Quercetin and some other organic compounds those were investigated from flower extracts of B. Variegata during HPLC and GC-MS analysis. The finding of this study supports the use of B. Variegata flower formulation in folk medicines. 相似文献
40.
Muhammad Afzal Imran Kazmi Anwarulabedin Mohsin Quazi Aftab Ahmad Fahad A. Al-Abaasi Faisal Imam Khalid Saad Alharbi Sami I. Alzarea Ameeduzzafar Zafar 《Saudi Journal of Biological Sciences》2021,28(6):3418-3423
The 6-shogaol, is a flavanone type flavonoid that is abundant in citrus fruit and has a wide range of pharmacological effects. The present study attempted to evaluate the antiurolithic effect of 6-shogaol on ethylene glycol (EG) and ammonium chloride (AC)-induced experimental urolithiasis in rats. The efficacy of 6-shogaol 50 mg/kg and 100 mg/kg was studied in EG 0.75% (V/V) and AC 1% (W/V) experimentally induced urolithiasis in rats for 21 days. The weight difference, urine volume, the levels of calcium, phosphate, magnesium, oxalate and uric acid in urine was observed. The blood urea nitrogen, creatinine, uric acid in serum and levels of malondialdehyde (MDA) and glutathione (GSH) were also measured. Histopathological analyses in kidneys were also performed. The rats weights were higher in the 6-shogaol groups than the urolithiasis group. EG caused a significant increase in serum creatinine (p < 0.05), BUN (P < 0.001), and uric acid (p < 0.01) while treatment with Cystone (750 mg/kg), and 6-shogaol (50 and 100 mg/kg) showed the significant reduction in increased serum levels of creatinine (p < 0.001), uric acid (p < 0.01) and BUN (p < 0.001). Administration of EG and AC showed statistically significant (p < 0.001) elevated levels of MDA and reduction in GSH levels. Treatment of Cystone (750 mg/kg), and 6-shogaol (50 and 100 mg/kg) significantly (p < 0.001) reduced MDA levels and an increase GSH levels as compared to EG and AC-treated group. The histological findings further attested antiurolithiatic properties of 6-shogaol. The present study attributed clinical shreds of evidence first time that claiming the significant antiurolithic effect of 6-shogaol and could be a cost-effective candidate for the prevention and treatment of urolithiasis. 相似文献