全文获取类型
收费全文 | 211篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
232篇 |
出版年
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 15篇 |
2012年 | 10篇 |
2011年 | 7篇 |
2010年 | 15篇 |
2009年 | 7篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 4篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1982年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1968年 | 2篇 |
1958年 | 5篇 |
1957年 | 2篇 |
1956年 | 4篇 |
1955年 | 2篇 |
1954年 | 2篇 |
1953年 | 4篇 |
1952年 | 5篇 |
1951年 | 2篇 |
1950年 | 2篇 |
1949年 | 1篇 |
1918年 | 1篇 |
排序方式: 共有232条查询结果,搜索用时 15 毫秒
51.
52.
53.
Sayed M. Riyadh Shojaa A. El‐Motairi Hany E. A. Ahmed Khaled D. Khalil EL‐Sayed E. Habib 《化学与生物多样性》2018,15(9)
2‐(1‐{4‐[(4‐Methylphenyl)sulfonamido]phenyl}ethylidene)thiosemicarbazide ( 3 ) was exploited as a starting material for the synthesis of two novel series of 5‐arylazo‐2‐hydrazonothiazoles 6a – 6j and 2‐hydrazono[1,3,4]thiadiazoles 10a – 10d , incorporating sulfonamide group, through its reactions with appropriate hydrazonoyl halides. The structures of the newly synthesized products were confirmed by spectral and elemental analyses. Also, the antimicrobial, anticancer, and DHFR inhibition potency for two series of thiazoles and [1,3,4]thiadiazoles were evaluated and explained by molecular docking studies and SAR analysis. 相似文献
54.
KEN W. SMITH ALI AGHNAJ MOHAMMED EL BEKKAY WIDADE OUBROU MOHAMMED RIBI MARIA JIMENEZ ARMESTO CHRISTOPHER G. R. BOWDEN 《Ibis》2008,150(4):728-734
The Northern Bald Ibis Geronticus eremita is a globally threatened species with its main remaining world population breeding in an area of sea cliffs and coastal semi‐desert steppe near Agadir in southern Morocco. Between 1998 and 2002, we showed experimentally that the small‐scale provision of fresh water near the breeding colonies led to an increase in the productivity of the birds. The increase was greatest in years with low natural rainfall but was positive in all years tested. The supplementary fresh water appears to help buffer productivity against the impacts of low rainfall and its provision is now part of the ongoing conservation measures for this species. 相似文献
55.
RENATA JACH ELŻBIETA MACHANIEC ALFRED UCHMAN 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2012,45(3):342-355
Jach, R., Machaniec, E. & Uchman, A. 2011: The trace fossil Nummipera eocenica from the Tatra Mountains, Poland: morphology and palaeoenvironmental implications. Lethaia, Vol. 45, pp. 342–355. The tubular trace fossil Nummipera eocenica Hölder 1989 occurs in a single stratigraphical horizon in Eocene nummulitic limestones of the Tatra Mountains, Poland. The wall of N. eocenica is built of Discocyclina and Nummulities (larger foraminifera) tests, very rarely of the Ditrupa (Polychaeta) tube fragments, bivalve shell fragments, echinoid spines and coralline algae. Morphotype are distinguished on the basis of wall composition and structure. Morphotype A is dominated by fusiform Discocyclina tests, which were preferentially selected by the trace makers for construction of a well‐constructed and resistant wall. Morphotype B contains more robust tests of Nummulites, while morphotype C is dominated by saddle‐shaped tests of Discocyclina. Nummipera eocenica was produced during a period of seafloor stabilization caused by a deepening. The succession of the morphotypes B, A reflects diminishing energy and increasing water depth. Probably morphotype C represents even lower energy environment than morphotype A. The trace fossil is interpreted as a domichnion, which wall was constructed for protection. The trace maker can be considered between polychaetes and crustaceans; however, comparisons to the closest recent analogues, the polychaete Diopatra cuprea or alpheid shrimps, are not satisfactory. □Bartonian, burrow, Carpathians, large foraminifera, trace fossils. 相似文献
56.
The present study was initiated to determine whether dietary supplemental L-carnitine and ascorbic acid affect growth performance, carcass yield and composition, abdominal fat and plasma L-carnitine concentration of broiler chicks reared under normal and high temperature. During the experiment, two temperature regimes were employed in two experimental rooms, which were identical but different in environmental temperature. The regimes were thermoneutral (20-22°C for 24 h) or recycling hot (34-36°C for 8 h and 20-22°C for 16 h). One-day-old broiler chicks (ROSS) were used in the experiment. A 2 x 2 x 2 factorial arrangement was employed with two levels (0 and 50 mg/kg) of supplemental L-carnitine and two levels (0 or 500 mg/kg) of supplemental ascorbic acid in drinking water under thermoneutral or high temperature regimes. Body weight gain was affected by high temperature. However, body weight gain was significantly improved in animals receiving supplemental L-carnitine, ascorbic acid or L-carnitine + ascorbic acid compared to animals receiving unsupplemented diet under high temperature. On the other hand, supplemental L-carnitine or L-carnitine + ascorbic acid reduced body weight gain under thermoneutral condition. Supplemental ascorbic acid significantly improved feed conversion efficiency, the improvement was relatively greater under high temperature. The L-carnitine content in the plasma was higher in the groups receiving supplemental L-carnitine and ascorbic acid under high temperature, while broilers fed supplemental L-carnitine and ascorbic acid had a decreased level of plasma L-carnitine concentration under normal temperature. It is concluded that dietary supplemental L-carnitine or L-carnitine + ascorbic acid may have positive effects on body weight gain, carcass weight under high temperature conditions. 相似文献
57.
D. Jabborova R.Z. Sayyed A. Azimov Z. Jabbarov A. Matchanov Y. Enakiev Alaa Baazeem Ayman EL Sabagh Subhan Danish Rahul Datta 《Saudi Journal of Biological Sciences》2021,28(9):5268-5274
Ginger is used as one of the important ingredients in traditional as well as modern medicine besides as a spice. It boosts immunity and is a rich source of many biologically active substances and minerals. Although it is a medicinally important crop, its productivity is, however, affected due to poor nutrient management and therefore it requires an adequate supply of nutrients in the form of inorganic fertilizers or organic manuring, or a mixture of both. In this context, the present study was aimed to investigate the effect of mineral fertilizers on the content of mineral elements in the ginger rhizome, on soil enzyme activity, and soil properties. Lysimeter experiments were conducted at the Institute of Genetics and Plant Experimental Biology, Kibray, Tashkent region, Uzbekistan. The experiment comprised of four treatments T1 – Control, T2 - N75P50K50 kg/ha, T3 - and T4 - N100P75K75 + B3Zn6Fe6 kg/ha. The results showed that the application of N125P100K100 kg/ha increased rhizome K content by 49%, P content by 20%, and Na content by 58% as compared to control without fertilizer. While the application of N100P75K75 + B3Zn6Fe6 kg/ha showed a significant enhancement in rhizome K, Ca, P, Mg, Na, Fe, Mn, Zn, Cu, Cr, Mo, and Si contents over the control. This treatment also improved active P content by 29%, total P content by 80%, total K content 16%, and N content by 33% content, and the activities of urease, invertase, and catalase activities as compared to control of without mineral fertilizer and control respectively. Thus the application of NPK + BZnFe at the rate of 100:75:75:3:6:6 kg/ha helps in improving macroelements and microelements in the ginger rhizome and activities of soil enzymes that helps in mineral nutrition of the rhizome. 相似文献
58.
Hamza Gadhoumi Martinez-Rojas Enriqueta Tounsi Moufida Saidani Hayouni EL Akrem 《Biology Bulletin》2021,48(6):667-672
Biology Bulletin - Erodium glaucophyllum, Erodium hirtum and Erodium guttatum were medicinal herbs from a southern Mediterranean known for its health benefits. There is a strong demand for the find... 相似文献
59.
Lamia Sakouhi Sondès Rahoui Marouane Ben Massoud Shintaro Munemasa Ezzeddine EL Ferjani Yoshiyuki Murata Abdelilah Chaoui 《Journal of Plant Growth Regulation》2016,35(4):1064-1073
Impact of exogenous calcium and ethylene glycol tetraacetic acid (EGTA) supplement on chickpea (Cicer arietinum L.) germinating seeds exposed to cadmium stress for 6 days was studied. Ca and EGTA late treatment (3 days) alleviated growth inhibition and decreased Cd accumulation as well as lipid peroxidation and protein carbonylation in both root and shoot cells. Exogenous effector application relieved Cd-induced cell death which was associated with a constant level of ATP, which was considered as an apoptotic-like process. Redox balance was examined through the study of the redox state of pyridine nucleotide couples NAD+/NADH and NADP+/NADPH as well as their related oxidative [NAD(P)H-oxidase] and dehydrogenase (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and malate dehydrogenase) enzyme activities. The present research illustrated an ameliorative effect of Ca and EGTA on growth of Cd-exposed chickpea seedlings that occurs through the protection of sensitive cell sites from Cd-induced oxidation, namely membrane lipids and proteins, rather than the improvement of recycling capabilities of the cellular reducing power. 相似文献
60.