全文获取类型
收费全文 | 444篇 |
免费 | 30篇 |
专业分类
林业 | 21篇 |
农学 | 15篇 |
基础科学 | 2篇 |
107篇 | |
综合类 | 45篇 |
农作物 | 25篇 |
水产渔业 | 34篇 |
畜牧兽医 | 188篇 |
园艺 | 2篇 |
植物保护 | 35篇 |
出版年
2023年 | 2篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 20篇 |
2012年 | 32篇 |
2011年 | 38篇 |
2010年 | 19篇 |
2009年 | 18篇 |
2008年 | 21篇 |
2007年 | 22篇 |
2006年 | 16篇 |
2005年 | 20篇 |
2004年 | 12篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1965年 | 3篇 |
1964年 | 5篇 |
1963年 | 4篇 |
排序方式: 共有474条查询结果,搜索用时 15 毫秒
51.
J. Staehelin A. Waldvogel J. L. Collett Jr. R. Dixon R. Heimgartner W. Henrich C. Hsu L. Li L. Mosimann B. Oberholzer A. S. H. Prevot W. Schmid T. Schumann M. Steiner M. Volken B. Zinder 《Water, air, and soil pollution》1993,68(1-2):1-14
Wet deposition plays an important role as a mechanism for cleansing of the polluted troposphere. Fluxes of pollutants from the atmosphere to earth's surface can affect soil and aquatic ecosystems. The investigation of the pollutant incorporation into wet deposition is therefore of considerable interest for environmental research. The project “Winter precipitation at Mount Rigi” addresses the processes determining the chemical composition of wet deposition through an integrated approach considering atmospheric physical and chemical processes and their complex interactions. The investigated topics include: aerosol and gas scavenging, atmospheric chemistry (cloud water chemistry), cloud physics and dynamics. The design of the experiment, using three ground based measuring stations at the northwestern slope of the mountain, and the conceptual ideas using case study investigations are discussed. 相似文献
52.
Malm O Guimarães JRD Castro MB Bastos WR Viana JP Branches FJP Silveira EG Pfeiffer WC 《Water, air, and soil pollution》1997,97(1-2):45-51
Informal economy of gold mining has contaminated some important river basins in Amazon. Follow-up studies on critical compartments showed some areas with high Hg levels in fish as well as in human hair samples. Average Hg in piscivorous fish in the Madeira river itself was 846 ppb (N=284) with a maximum of 3921 ppb. Mercury in fish from non polluted areas in this basin shows high variability, even for single species. A seasonal variation in Hg content was observed, with higher values at the end of the dry season. In the upper Tapajós basin comparable values were found for fish but with a definite decreasing trend downstream. Average value for piscivorous fish in the whole Tapajós basin is 482 ppb (N=122) with a maximum value of 3770 ppb. Hair Hg was higher in fishing villages in the Tapajós (average: 17 ppm; with N=432 and maximum value of 176 ppm) than in the Madeira (average: 9 ppm; N=169; maximum 71 ppm), and data from some areas of the Tapajós suggest a decrease with time. Mercury was much higher in urine of goldshop workers in Santarém (low Tapajós) than in Alta Floresta (high Tapajbs) and show a decreasing trend in both cases, probably related to the significant decline in gold mining activities during the study period (1986–1994). 相似文献
53.
Hsu FL Lin YH Lee MH Lin CL Hou WC 《Journal of agricultural and food chemistry》2002,50(21):6109-6113
Dioscorin, the tuber storage protein of yam (Dioscorea alata cv. Tainong No. 1), was purified to homogeneity by DE-52 ion-exchange chromatography. This purified dioscorin was shown by spectrophotometric methods to inhibit angiotensin converting enzyme (ACE) in a dose-dependent manner (12.5-750 microg, respectively, 20.83-62.5% inhibitions) using N-[3-(2-furyl)acryloyl]-Phe-Gly-Gly (FAPGG) as substrates. The 50% inhibition (IC(50)) of ACE activity was 6.404 microM dioscorin (250 microg corresponding to 7.81 nmol) compared to that of 0.00781 microM (0.0095 nmol) for captopril. The commercial bovine serum albumin and casein (bovine milk) showed less ACE inhibitory activity. The use of qualitative TLC also showed dioscorin as ACE inhibitors. Dioscorin showed mixed noncompetitive inhibitions against ACE; when 31.25 microg of dioscorin (0.8 microM) was added, the apparent inhibition constant (K(i)) was 2.738 microM. Pepsin was used for dioscorin hydrolysis at 37 degrees C for different times. It was found that the ACE inhibitory activity was increased from 51.32% to about 75% during 32 h hydrolysis. The smaller peptides were increased with increasing pepsin hydrolytic times. Dioscorin and its hydrolysates might be a potential for hypertension control when people consume yam tuber. 相似文献
54.
55.
New dammarane-type saponins from the galls of Sapindus mukorossi 总被引:2,自引:0,他引:2
Kuo YH Huang HC Yang Kuo LM Hsu YW Lee KH Chang FR Wu YC 《Journal of agricultural and food chemistry》2005,53(12):4722-4727
Five new dammarane-type saponins, 3beta,7beta,20(S),22-tetrahydroxydammar-24-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, 3beta,7beta,20(S),22,23-pentahydroxydammar-24-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, 3beta,7beta,20(S),22,25-pentahydroxydammar-23-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, 25-methoxy-3beta,7beta,20(S),22-tetrahydroxydammar-23-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, and 25-methoxy-3beta,7beta,20(R)-trihydroxydammar-23-ene-3-O-alpha-l-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, named sapinmusaponins A (1), B (2), C (3), D (4), and E (5), respectively, together with three known phenylpropanoid glycosides (6-8), were isolated from the galls of Sapindus mukorossi. The structures of these saponins were elucidated on the basis of spectroscopic analyses and chemical methods. Preliminary bioassay data revealed that saponins 1 and 3-5 showed moderate cytotoxic activity (ED50 approximately 9-18 microg/mL) against human tumor cell lines (Hepa59T/VGH, NCI, HeLa, and Med) and that 1-5 were inactive in vitro against HIV replication in H9 lymphocytes. 相似文献
56.
Inhibitory effect of caffeic acid phenethyl ester on angiogenesis, tumor invasion, and metastasis 总被引:10,自引:0,他引:10
Liao HF Chen YY Liu JJ Hsu ML Shieh HJ Liao HJ Shieh CJ Shiao MS Chen YJ 《Journal of agricultural and food chemistry》2003,51(27):7907-7912
Caffeic acid phenethyl ester (CAPE) derived from honeybee propolis has been used as a folk medicine and has several proven biological activities. The present study investigated the effect of CAPE on angiogenesis, tumor invasion, and metastasis. A cytotoxicity assay of CAPE in CT26 colon adenocarcinoma cells showed a dose-dependent decrease in cell viability but no significant influence on the growth of human umbilical vein epithelial cells (HUVEC). A low concentration of CAPE (1.5 microg/mL) inhibited 52.7% of capillary-like tube formation in HUVEC culture on Matrigel. CAPE (6 microg/mL)-treated CT26 cells showed not only inhibited cell invasion by 47.8% but also decreased expression of matrix metalloproteinase (MMP)-2 and -9. Vascular endothelial growth factor (VEGF) production from CT26 cells was also inhibited by treatment with CAPE (6 microg/mL). Intraperitoneal injection of CAPE (10 mg/kg/day) in BALB/c mice reduced the pulmonary metastatic capacity of CT26 cells accompanied with a decreased plasma VEGF level. CAPE treatment also prolonged the survival of mice implanted with CT26 cells. These results indicate that CAPE has potential as an antimetastatic agent. 相似文献
57.
Evaluation of corn fiber, cottonseed hulls, oat hulls and soybean hulls as roughage sources for ruminants 总被引:2,自引:0,他引:2
J T Hsu D B Faulkner K A Garleb R A Barclay G C Fahey L L Berger 《Journal of animal science》1987,65(1):244-255
An in situ trial (randomized complete block design) using cows, and a site and extent of digestion trial (Latin square design) using sheep were conducted to study the potential of corn fiber (CF), cottonseed hulls (CSH), oat hulls (OH) and soybean hulls (SH) as roughage sources for ruminants. Two feedlot trials with steers and one with lambs (completely randomized design with factorial arrangements of treatments) were conducted to study the potential of CF and SH as energy supplements relative to corn. In situ rate of ruminal dry matter (DM) disappearance (3 to 36 h) and extent of DM disappearance (36 h) indicated that CF and SH were more fermentable in the rumen compared with OH or CSH, with SH being the most fermentable. Total tract digestibilities of DM, organic matter (OM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were above 70% for sheep fed CF and SH diets, and were 50% or less for sheep fed OH and CSH diets. A ranking of by-products in terms of nutritive value followed the trend: CF greater than SH greater than OH greater than CSH. Lamb feedlot trial data showed that CF was of similar nutritive value to corn and of higher nutritive value than SH at the 50% level of supplementation. Corn-fed lambs responded better than CF- or SH-fed lambs at the 70% level of supplementation. Data from steer feedlot trials showed that CF was of similar quality to corn and of higher quality than SH. Dramatic differences exist in by-product feed utilization by ruminants. All by-products tested appeared to have some usefulness as dietary components. 相似文献
58.
Effects of tolazoline and yohimbine on xylazine-induced central nervous system depression, bradycardia, and tachypnea in sheep 总被引:2,自引:0,他引:2
W H Hsu D D Schaffer C E Hanson 《Journal of the American Veterinary Medical Association》1987,190(4):423-426
We compared the ability of tolazoline and yohimbine to antagonize xylazine-induced central nervous system depression, bradycardia, and tachypnea in 9 ewes and 5 rams. Once a week for 3 weeks, each sheep received one IV treatment of 0.4 mg xylazine/kg, 0.4 mg xylazine/kg followed in 10 minutes by 2 mg tolazoline/kg, or 0.4 mg xylazine/kg followed in 10 minutes by 0.2 mg yohimbine/kg. The order of the 3 treatments in each sheep was randomized. Xylazine alone caused recumbency for 41.0 +/- 3.7 minutes (mean +/- SEM). Tolazoline and yohimbine shortened the xylazine-induced recumbency to 12.1 +/- 0.9 minutes and 18.1 +/- 1.5 minutes, respectively. Sheep given xylazine alone had head droop for 34.0 +/- 5.4 minutes after rising. Head drooping of sheep given tolazoline or yohimbine was reduced to 10.1 +/- 1.7 minutes and 14.2 +/- 1.7 minutes, respectively. Both tolazoline and yohimbine reversed the bradycardia and tachypnea that followed xylazine administration. No statistical differences in the rate and magnitude of the reversal were observed between the 2 drugs. 相似文献
59.
60.