全文获取类型
收费全文 | 1462篇 |
免费 | 131篇 |
国内免费 | 3篇 |
专业分类
林业 | 132篇 |
农学 | 55篇 |
基础科学 | 6篇 |
266篇 | |
综合类 | 117篇 |
农作物 | 68篇 |
水产渔业 | 68篇 |
畜牧兽医 | 689篇 |
园艺 | 22篇 |
植物保护 | 173篇 |
出版年
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 21篇 |
2020年 | 34篇 |
2019年 | 20篇 |
2018年 | 48篇 |
2017年 | 51篇 |
2016年 | 69篇 |
2015年 | 58篇 |
2014年 | 57篇 |
2013年 | 97篇 |
2012年 | 107篇 |
2011年 | 117篇 |
2010年 | 62篇 |
2009年 | 47篇 |
2008年 | 100篇 |
2007年 | 87篇 |
2006年 | 82篇 |
2005年 | 85篇 |
2004年 | 63篇 |
2003年 | 61篇 |
2002年 | 51篇 |
2001年 | 24篇 |
2000年 | 33篇 |
1999年 | 24篇 |
1998年 | 15篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 15篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1971年 | 3篇 |
1969年 | 9篇 |
1968年 | 4篇 |
1965年 | 2篇 |
1958年 | 5篇 |
排序方式: 共有1596条查询结果,搜索用时 93 毫秒
991.
992.
Krista Mitchell Michele Barletta Steeve Giguère Jane Quandt David Osborn Eryn Watson Bradley Cohen Karl V. Miller 《Veterinary anaesthesia and analgesia》2021,48(3):356-363
ObjectiveTo compare oxygenation and ventilation in white-tailed deer (Odocoileus virginianus) anesthetized with two treatments with and without oxygen supplementation.Study designRandomized, blinded, crossover study.AnimalsA total of eight healthy adult white-tailed deer weighing 49–62 kg.MethodsEach deer was anesthetized twice intramuscularly: 1) treatment XK, xylazine (2 mg kg–1) and ketamine (6 mg kg–1) and 2) treatment XTZ, xylazine (2 mg kg–1) and tiletamine–zolazepam (4 mg kg–1). With the deer in sternal position, arterial and venous blood was collected before and at 30 minutes during administration of oxygen at 1 L minute–1 through a face mask. PaO2 and heart rate (HR) were compared using two-way repeated measures anova. pH, PaCO2 and lactate concentration were analyzed using mixed-effects linear models, p < 0.05.ResultsWhen breathing air, PaO2 was < 80 mmHg (10.7 kPa) in six and seven deer with XK and XTZ, respectively, and of these, PaO2 was < 60 mmHg (8.0 kPa) in three and five deer, respectively. With oxygen supplementation, PaO2 increased to 128 ± 4 and 140 ± 5 mmHg (17.1 ± 0.5 and 18.7 ± 0.7 kPa), mean ± standard error, with XK and XTZ, respectively (p < 0.001). PaO2 was not significantly different between treatments at either time point. HR decreased during oxygen supplementation in both treatments (p < 0.001). Lactate was significantly lower (p = 0.047) with XTZ than with XK (2.2 ± 0.6 versus 3.5 ± 0.6 mmol L–1) and decreased (p < 0.001) with oxygen supplementation (4.1 ± 0.6 versus 1.6 ± 0.6 mmol L–1). PaCO2 increased in XTZ during oxygen breathing.Conclusions and clinical relevanceTreatments XK and XTZ resulted in hypoxemia, which responded to oxygen supplementation. Both treatments are suitable for immobilization of white-tailed deer under the study circumstances. 相似文献
993.
994.
Delphine Bon Véronique Gilard Stéphane Massou Guénola Pérès Myriam Malet-Martino Robert Martino Franck Desmoulin 《Biology and Fertility of Soils》2006,43(2):191-198
This study demonstrates that 31P and 1H high resolution-magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR), a recently developed NMR technique, can be applied to the in vivo analysis of metabolites from an unstarved earthworm. The endogeic earthworm Aporrectodea caliginosa was cut into lengths and then the different body parts (anterior, middle, posterior) with the gut content were analyzed. With the HR-MAS NMR, metabolites show well-resolved signals, whereas, with conventional NMR, spectra are highly dependent on the gut content. 31P HR-MAS NMR has been used to evaluate the effect of an acute exposure of the earthworm to glyphosate. Our observations support a low toxicity of the herbicide and suggest that glyphosate could be trapped in the cutaneous mucus. Earthworms could therefore play a role in horizontal dispersion and stabilization of glyphosate in the drilosphere. Phosphorylated metabolites, such as phospholombricine and lombricine, were clearly identified and their amount measured during experiments. The 1H HR-MAS NMR method offers the opportunity to measure, on the same sample and simultaneously, both the hydrosoluble metabolites and lipids. The data on lipid location and relative succinate concentration shed light on the physiological and metabolic functions of the different body parts of the earthworm. 相似文献
995.
Al-Awwadi N Azay J Poucheret P Cassanas G Krosniak M Auger C Gasc F Rouanet JM Cros G Teissèdre PL 《Journal of agricultural and food chemistry》2004,52(4):1008-1016
A polyphenol extract from a Corbières (France) red wine (P, 200 mg/kg), ethanol (E, 1 mL/kg), or a combination of both (PE) was administered by daily gavage for 6 weeks to healthy control or streptozotocin (60 mg/kg i.v.)-induced diabetic rats (180-200 g). Treatment groups included C or D (untreated control or diabetic) and CP, CE, or CPE (treated control) or DP, DE, or DPE (treated diabetic). P treatment induced a reduction in body growth, food intake, and glycemia in both CP and DP groups. In DP, hyperglycemia was reduced when measured 1 h after daily treatment but not at sacrifice (no treatment on that day). The hyperglycemic response to the oral glucose tolerance test (OGTT) and plasma insulin at sacrifice were impaired similarly in DP and D groups. In contrast, in DE or DPE, body growth was partially restored while hyperglycemia was reduced both during treatment and at sacrifice. In addition, hyperglycemia response to OGTT was reduced and plasma insulin was higher in DE or DPE than in D animals, indicating a long-term correction of diabetes in ethanol-treated animals. Morphometric studies showed that ethanol partially reversed the enlarging effect of diabetes on the mesenteric arterial system while the polyphenolic treatment enhanced it in the absence of ethanol. In summary, our study shows that (i). a polyphenol extract from red wine ("used at a pharmacological" dose) reduces glycemia and decreases food intake and body growth in diabetic and nondiabetic animals and (ii). ethanol ("nutritional" dose) administered alone or in combination with polyphenols is able to correct the diabetic state. Some of the effects of polyphenols were masked by the effects of ethanol, notably in diabetic animals. Further studies will determine the effect of "nutritional" doses of polyphenols as well as their mechanism of action. 相似文献
996.
Rondini L Peyrat-Maillard MN Marsset-Baglieri A Fromentin G Durand P Tomé D Prost M Berset C 《Journal of agricultural and food chemistry》2004,52(13):4338-4343
Ferulic acid (FA) is reported as a good antioxidant absorbed by human or rat but only few data deal with the influence of the food matrix on its bioavailability and with its potential protection against cardiovascular diseases and cancer. Wheat bran is used as a source of ferulic acid, the compound being mainly bound to arabinoxylans of the plant cell walls. Pharmacokinetic profiles of FA and its metabolites are established in rats. Free and conjugated FA quickly appear in plasma, reach a plateau 1 h after intake and remain approximately constant at 1 microM up to 24 h. 2.3% of FA are eliminated in urine. Compared with results obtained after intake of free FA, the presence of FA-arabinoxylans bonds in the food matrix increases the occurrence time of FA in the organism and decreases the level of urinary excretion in 24 h. Nevertheless, sulfated FA is still the main plasmatic form. The antioxidant activity of plasmas of rats fed with a standard diet (containing no FA), pure ferulic acid (5.15 mg FA/kg bw) or bran (4.04 mg FA/kg bw) are measured in an ex vivo test using AAPH as free radical inducer. Plasmas of rats fed with bran show a better antioxidant activity than the control group and the pure FA supplemented group, increasing the resistance of erythrocytes to hemolysis by factors of 2 and 1.5, respectively. These results show the good bioavailability of FA from bran and its potential efficiency to protect organism against pathology involving radical steps of development. 相似文献
997.
P Leone M Nègre M Gennari V Boero R Celis J Cornejo 《Journal of agricultural and food chemistry》2002,50(2):291-298
Adsorption of imazapyr (IMZ), imazethapyr (IMZT), and imazaquin (IMZQ) was studied on two smectite-humic acid and two smectite-ferrihydrite binary systems prepared by treating a Wyoming smectite with a humic acid extracted from soil (4 and 8% w/w of the smectite) and with just-precipitated synthetic ferrihydrite (8 and 16% w/w of the smectite). Adsorption of the three herbicides on the smectite was not measurable at pH >4.5, presumably because of negative charges on the surface of the smectite. Adsorption on the smectite-humic acid systems was also not measurable, presumably because of negative charges on the surface, despite the high affinity of the three herbicides for humic acid, the adsorption order of which was IMZ < IMZT < IMZQ. Adsorption decreased in the order IMZ < IMZT < IMZQ on the smectite-ferrihydrite systems and IMZQ < IMZT < IMZ on ferrihydrite, although here the differences were small. These results show that even though pure smectite cannot adsorb herbicides, it modifies the adsorption capacity of ferrihydrite. The mutual interaction of active phases such as humic acid, ferrihydrite, and smectite alters the characteristics of the resulting surface and hence the adsorption process. Investigations of herbicide adsorption have been seen to produce more reliable results if conducted on polyphasic systems rather than on single soil components. 相似文献
998.
999.
Lebreton A Lakisic G Job V Fritsch L Tham TN Camejo A Matteï PJ Regnault B Nahori MA Cabanes D Gautreau A Ait-Si-Ali S Dessen A Cossart P Bierne H 《Science (New York, N.Y.)》2011,331(6022):1319-1321
Intracellular pathogens such as Listeria monocytogenes subvert cellular functions through the interaction of bacterial effectors with host components. Here we found that a secreted listerial virulence factor, LntA, could target the chromatin repressor BAHD1 in the host cell nucleus to activate interferon (IFN)-stimulated genes (ISGs). IFN-λ expression was induced in response to infection of epithelial cells with bacteria lacking LntA; however, the BAHD1-chromatin associated complex repressed downstream ISGs. In contrast, in cells infected with lntA-expressing bacteria, LntA prevented BAHD1 recruitment to ISGs and stimulated their expression. Murine listeriosis decreased in BAHD1(+/-) mice or when lntA was constitutively expressed. Thus, the LntA-BAHD1 interplay may modulate IFN-λ-mediated immune response to control bacterial colonization of the host. 相似文献
1000.
Mairesse Y de Bohan A Frasinski LJ Merdji H Dinu LC Monchicourt P Breger P Kovacev M Taïeb R Carré B Muller HG Agostini P Salières P 《Science (New York, N.Y.)》2003,302(5650):1540-1543
Subfemtosecond light pulses can be obtained by superposing several high harmonics of an intense laser pulse. Provided that the harmonics are emitted simultaneously, increasing their number should result in shorter pulses. However, we found that the high harmonics were not synchronized on an attosecond time scale, thus setting a lower limit to the achievable x-ray pulse duration. We showed that the synchronization could be improved considerably by controlling the underlying ultrafast electron dynamics, to provide pulses of 130 attoseconds in duration. We discuss the possibility of achieving even shorter pulses, which would allow us to track fast electron processes in matter. 相似文献