全文获取类型
收费全文 | 188篇 |
免费 | 3篇 |
专业分类
林业 | 26篇 |
农学 | 9篇 |
基础科学 | 1篇 |
54篇 | |
综合类 | 22篇 |
农作物 | 5篇 |
水产渔业 | 11篇 |
畜牧兽医 | 49篇 |
园艺 | 1篇 |
植物保护 | 13篇 |
出版年
2021年 | 1篇 |
2018年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 19篇 |
2012年 | 12篇 |
2011年 | 17篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 13篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1952年 | 1篇 |
排序方式: 共有191条查询结果,搜索用时 16 毫秒
11.
G.?J.?Dietrich R.?Kowalski M.?Wojtczak S.?Dobosz K.?Goryczko A.?CiereszkoEmail author 《Fish physiology and biochemistry》2005,31(1):1-9
The present study investigated the effects of sequential collection of milt, time of post-mortem storage and anesthesia on rainbow trout (Oncorhynchus mykiss) sperm motility parameters (using computer-assisted sperm analysis – CASA) as well as seminal plasma osmolality and sperm
concentration. The post-mortem storage and time of anesthesia altered motility characteristics of rainbow trout sperm to different extents. The moderate
impact of time of anesthesia was manifested in a shortened duration of sperm motility after 10 min exposure of fish to anesthetic.
The prolonged post-mortem storage (≥40–60 min), in addition to lowering sperm motility duration, also significantly influenced sperm motility parameters,
such as sperm velocities, percentage of motile sperm and sperm trajectory parameters. These results clearly demonstrate that
when milt from sacrificed fish is used for sperm motility studies, the time of post-mortem storage significantly alters sperm motility characteristics. Since sperm motility rate and swimming velocity could predict
fertilizing ability, detrimental effects of prolonged post-mortem storage may lead to reduced fertilization success. Sperm concentration and seminal plasma osmolality were lower in the first
fractions and increased with successive collections of milt. It suggests the presence of urine contamination of the first
milt fractions which were collected by stripping. Therefore, testing of sperm concentration and/or seminal plasma osmolality
should be mandatory while handling stored milt. 相似文献
12.
Vergara C von Baer D Mardones C Wilkens A Wernekinck K Damm A Macke S Gorena T Winterhalter P 《Journal of agricultural and food chemistry》2012,60(4):929-933
Health benefits of trans-resveratrol and other stilbenes in grapes, must, and wine have been pointed out by numerous authors. Less attention has been paid to the presence of stilbene derivatives in viticultural residues, such as grape canes. The present work reports the first results of a systematic study of stilbene levels in different grape varieties and cultivation areas in Chile, to evaluate their potential as an alternative source of bioactive stilbenes. In all cane samples, the predominant stilbene is trans-resveratrol, followed by ε-viniferin and piceatannol. In canes of Pinot noir up to 5590 ± 172 mg kg(-1) of trans-resveratrol and up to 6915 ± 175 mg kg(-1) of total stilbenes were detected. The observed concentrations of stilbenes in canes of Pinot noir from southern Chile until now are higher than those reported previously for this red variety. However, the highest concentration of total stilbenes observed in the analyzed samples was in the canes of white variety Gewürztraminer with 7857 ± 498 mg kg(-1). Preliminary results indicate that these levels can evolve if canes are left for some months on the vineyard after pruning, observing an increase during the first 2 months and a decrease after this period. 相似文献
13.
Summary The alkali extract (5% KOH) from beech holocellulose was fractionated by ion exchange chromatography, resulting in several fractions containing different amounts of polyoses and lignin. The separated polyoses varied to some extent in the ratios of their sugar components. Three different 4-0-methylglucurono-xylans and three arabinogalactans were isolated. There was a direct relationship between the chemical composition and the ultrastructure of the fractions. Those containing a pure 4-0-methylglucurono-xylan showed bundles of thin and stiff fibrils while in fractions with a high percentage of lignin coiled fibrils and globular particles could be observed in the electron microscope.Submitted by Arbeitsgemeinschaft Industrieller Forschungsvereinigungen (AIF) via Deutsche Gesellschaft für Holzforschung. The conscientious preparation of the electron microscopic specimens by Miss U. Schwarz is appreciated. 相似文献
14.
Brimhall GH Chadwick OA Lewis CJ Compston W Williams IS Danti KJ Dietrich WE Power ME Hendricks D Bratt J 《Science (New York, N.Y.)》1992,255(5045):695-702
Soils are differentiated vertically by coupled chemical, mechanical, and biological transport processes. Soil properties vary with depth, depending on the subsurface stresses, the extent of mixing, and the balance between mass removal in solution or suspension and mass accumulation near the surface. Channels left by decayed roots and burrowing animals allow organic and inorganic detritus and precipitates to move through the soil from above. Accumulation occurs at depths where small pores restrict further passage. Consecutive phases of translocation and root growth stir the soil; these processes constitute an invasive dilatational process that leads to positive cumulative strains. In contrast, below the depth of root penetration and mass additions, mineral dissolution by descending organic acids leads to internal collapse under overburden load. This softened and condensed precursor horizon is transformed into soil by biological activity, which stirs and expands the evolving residuum by invasion by roots and macropore networks that allows mixing of materials from above. 相似文献
15.
von der Linde D 《Science (New York, N.Y.)》2003,302(5649):1345-1346
16.
Boyen HG Kästle G Weigl F Koslowski B Dietrich C Ziemann P Spatz JP Riethmüller S Hartmann C Möller M Schmid G Garnier MG Oelhafen P 《Science (New York, N.Y.)》2002,297(5586):1533-1536
Gold nanoparticles ranging in diameter from 1 to 8 nanometers were prepared on top of silicon wafers in order to study the size dependence of their oxidation behavior when exposed to atomic oxygen. X-ray photoelectron spectroscopy showed a maximum oxidation resistance for "magic-number" clusters containing 55 gold atoms. This inertness is not related to electron confinement leading to a size-induced metal-to-insulator transition, but rather seems to be linked to the closed-shell structure of such magic clusters. The result additionally suggests that gold-55 clusters may act as especially effective oxidation catalysts, such as for oxidizing carbon monoxide. 相似文献
17.
D'aes J Hua GK De Maeyer K Pannecoucque J Forrez I Ongena M Dietrich LE Thomashow LS Mavrodi DV Höfte M 《Phytopathology》2011,101(8):996-1004
Pseudomonas CMR12a was previously selected as an efficient biocontrol strain producing phenazines and cyclic lipopeptides (CLPs). In this study, biocontrol capacity of Pseudomonas CMR12a against Rhizoctonia root rot of bean and the involvement of phenazines and CLPs in this ability were tested. Two different anastomosis groups (AGs) of Rhizoctonia solani, the intermediately aggressive AG 2-2 and the highly aggressive AG 4 HGI, were included in growth-chamber experiments with bean plants. The wild-type strain CMR12a dramatically reduced disease severity caused by both R. solani AGs. A CLP-deficient and a phenazine-deficient mutant of CMR12a still protected bean plants, albeit to a lesser extent compared with the wild type. Two mutants deficient in both phenazine and CLP production completely lost their biocontrol activity. Disease-suppressive capacity of CMR12a decreased after washing bacteria before application to soil and thereby removing metabolites produced during growth on plate. In addition, microscopic observations revealed pronounced branching of hyphal tips of both R. solani AGs in the presence of CMR12a. More branched and denser mycelium was also observed for the phenazine-deficient mutant; however, neither the CLP-deficient mutant nor the mutants deficient in both CLPs and phenazines influenced hyphal growth. Together, results demonstrate the involvement of phenazines and CLPs during Pseudomonas CMR12a-mediated biocontrol of Rhizoctonia root rot of bean. 相似文献
18.
R A Dietrich S H Amosson R P Crawford V C Beal 《Journal of the American Veterinary Medical Association》1991,198(1):78-80
Initial and cumulative reactor rates for strain 19 vaccinates and nonvaccinates were significantly (P less than 0.001) lower for beef herds containing variable proportions of vaccinates, compared with reactor rates in nonvaccinated herds. In addition, significant (P less than 0.005) reduction in cumulative incidence was observed in nonvaccinated and strain 19-vaccinated cattle as the proportion of vaccinates within the herd increased from 1 to 19%, 20 to 39%, 40 to 59%, and 60 to 100%. Duration of quarantine and number of herd tests were not reduced in herds with strain 19-vaccinated cattle. In herds released from quarantine, duration of quarantine and number of tests were positively correlated to proportion of the herd vaccinated. In nonvaccinated herds released from quarantine, effect of herd size was documented by strong positive (P = 0.042) correlation with duration of quarantine and slightly weaker correlation (P = 0.095) with number of tests. 相似文献
19.
Angelika Brandt Bertram Schnorr Dietrich Weyrauch 《Anatomia, histologia, embryologia》1983,12(1):7-24
The ultrastructure of the adipose tissue connective tissue, mesothelium and milky spots forming the greater cmentum of sheep and goats was studied.
The mixture of connective tissue fibers and adipose tissue is arranged in submesothelial, marginal, and central layers. – The mesothelial cells are covered by a surface coat and are characterized by numerous microvilli and vesicles. The number of milky spots varies greatly. They are commonly found on the surface of the omentum and are covered by modified mesothelial cells; their interior contains macrophages and lymphoid cells. 相似文献
The mixture of connective tissue fibers and adipose tissue is arranged in submesothelial, marginal, and central layers. – The mesothelial cells are covered by a surface coat and are characterized by numerous microvilli and vesicles. The number of milky spots varies greatly. They are commonly found on the surface of the omentum and are covered by modified mesothelial cells; their interior contains macrophages and lymphoid cells. 相似文献
20.
Dietrich U 《Clinical Techniques in Small Animal Practice》2005,20(2):108-116
Cats are usually presented at a very late stage in the course of glaucoma when the eye is already blind. Secondary glaucoma because of another underlying ocular lesion is the most common form of glaucoma in the cat and is frequently associated with chronic anterior uveitis or intraocular neoplasia. Chronic stages of glaucoma in the cat are characterized by buphthalmus, anterior lens luxation, and exposure keratitis secondary to the enlarged globe. Ophthalmoscopic signs of glaucomatous retinal degeneration are only noticed in very advanced stages. Treatment of glaucoma in cats is usually aimed to keep the eye comfortable and within a normal intraocular pressure range. However, many antiglaucoma medications that are successfully used in humans and dogs are not very well tolerated by cats and, therefore, the selection of recommended drugs is limited in this species. 相似文献