全文获取类型
收费全文 | 14120篇 |
免费 | 1072篇 |
国内免费 | 73篇 |
专业分类
林业 | 629篇 |
农学 | 824篇 |
基础科学 | 125篇 |
2004篇 | |
综合类 | 1669篇 |
农作物 | 496篇 |
水产渔业 | 1042篇 |
畜牧兽医 | 7077篇 |
园艺 | 228篇 |
植物保护 | 1171篇 |
出版年
2023年 | 90篇 |
2021年 | 88篇 |
2020年 | 122篇 |
2019年 | 202篇 |
2018年 | 373篇 |
2017年 | 345篇 |
2016年 | 334篇 |
2015年 | 306篇 |
2014年 | 326篇 |
2013年 | 571篇 |
2012年 | 482篇 |
2011年 | 574篇 |
2010年 | 464篇 |
2009年 | 422篇 |
2008年 | 565篇 |
2007年 | 589篇 |
2006年 | 477篇 |
2005年 | 524篇 |
2004年 | 410篇 |
2003年 | 453篇 |
2002年 | 361篇 |
2001年 | 764篇 |
2000年 | 721篇 |
1999年 | 593篇 |
1998年 | 171篇 |
1997年 | 164篇 |
1996年 | 126篇 |
1995年 | 150篇 |
1994年 | 156篇 |
1993年 | 120篇 |
1992年 | 321篇 |
1991年 | 346篇 |
1990年 | 294篇 |
1989年 | 266篇 |
1988年 | 272篇 |
1987年 | 320篇 |
1986年 | 245篇 |
1985年 | 193篇 |
1984年 | 170篇 |
1983年 | 147篇 |
1982年 | 94篇 |
1981年 | 83篇 |
1980年 | 79篇 |
1979年 | 141篇 |
1978年 | 94篇 |
1977年 | 73篇 |
1975年 | 77篇 |
1974年 | 79篇 |
1971年 | 69篇 |
1969年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
A sandwich-ELISA was developed for the detection of soluble Taenia hydatigena antigens in fecal samples of dogs. Affinity-purified polyclonal catching antibodies and alkaline phosphatase-conjugated detecting antibodies were employed, which had been obtained from rabbits hyperimmunized with excretory/secretory antigens derived from in vitro maintained adult Taenia hydatigena. The assay allowed the detection of 800 ng T. hydatigena antigen g-1 of feces as a lower limit. Six helminth-free dogs were each infected with 10 T. hydatigena cysticerci isolated from Swiss sheep. After prepatent periods ranging from 57 to 71 days, the dogs started to excrete Taenia eggs and/or proglottids. The ELISA detected Taenia antigens in all six dogs during the prepatent period starting individually between Day 18 and 45 post-infection (p.i.). Anthelmintic treatment of three dogs at Day 95 p.i. resulted in elimination of the cestodes and within the 5 following days in the disappearance of Taenia antigens from feces. The specificity of the assay was evaluated by testing crude antigens derived from helminths or bacteria. Four Taenia species showed cross-reactivity at concentrations of 5 micrograms protein ml-1. Conversely, no cross-reactions occurred with various antigen batches derived from Echinococcus granulosus, E. multilocularis, Dipylidium caninum, Mesocestoides corti, Diphyllobothrium sp., Toxocara canis and bacterial antigens (Salmonella and Escherichia). Moreover, fecal samples from dogs naturally infected with T. canis (n: 13), hookworms (n: 2), Trichuris vulpis (n: 13) and of 10 dogs with mixed infections with these three nematode groups were tested, and results confirmed the high degree of specificity. The Taenia antigens detectable by this ELISA remained immunologically stable in native feces stored at +25 degrees, +4 degrees or at -20 degrees C for at least 5 days. 相似文献
963.
Y Sasaki M Hayashi K Matsumoto S Namioka 《The Japanese journal of veterinary research》1990,38(2):35-42
An altered expression of the Yc subunit gene of rat glutathione S-transferase (GST) in the liver of the LEC rat, which is a mutant strain with spontaneous hereditary hepatitis associated with severe jaundice, has been reported. To provide further information concerning the structure of the Yc subunit gene, we carried out the Southern blot hybridization analysis of DNA samples from rats of eight different inbred strains including LEC with cDNA complementary to mRNA specific for the Yc subunit of rat liver GST as a probe. The hybridization patterns of the DNA samples from rats belonging to the different inbred strains showed interstrain variation in the length of restriction fragments with four restriction endonucleases. Since the DNA samples prepared from several rats of one inbred strain gave an identical hybridization pattern, the restriction fragment patterns for the Yc gene could be used as markers for genetic monitoring of inbred rat strains. Although the altered expression of Yc-Yc activity of GST has been observed in the liver of the LEC rat, the characteristic changes in the gene structure of the Yc subunit of LEC rat were not detected in the present hybridization analysis. 相似文献
964.
H Endo Y Hayashi T Komiya E Narushima M Sasaki 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(5):533-537
The architecture of the M. caninus in the elongated nose was examined in the Asian elephant (Elephas maximus). The following complicated musculature of the M. caninus was observed in the proximal and distal regions of the nose: (1) Proximal region: In the superficial layer, the longitudinal bundles are confirmed in the dorsal part, and the obliquely-oriented ones in the ventral part. In the middle layer, some bundles run ventro-distally, while other ones represent longitudinally-oriented running. The deep layer consists of complicated architecture of many bundles. Some muscle bundles run medio-laterally, while the others extend proximo-distally in this space. (2) Distal region: In the dorsal part of the M. caninus, the bundles run at deep-superficial direction, while in the ventral part the bundles are longitudinally arranged. The bundles run at lateral direction near the septum of the nasal conduits. The N. facialis and N. infraorbitalis send many branches in the lateral area of the M. caninus in the trunk. This muscle architecture of multi-oriented bundles and well-developed innervation to them suggest that they enable the elongated nose to act as a refined manipulator in the Asian elephant. 相似文献
965.
Jean K. Reichle DVM MS Richard A. Peterson II DVM Mary B. Mahaffey DVM MS Curtis G. Schelling VMD MS Paul Y. Barthez DVM PHD 《Veterinary radiology & ultrasound》2003,44(4):433-437
Four dogs with ureteral fibroepithelial polyps, ranging from 9-12 years of age, are presented in this report. The patients presented with urinary incontinence, urinary tract infection, and/or polydypsia and pollakiuria. All dogs were intact at the time of diagnosis or for the majority of their lives and three were male. Various diagnostic procedures were performed including ultrasonography, contrast radiography, and nuclear scintigraphy. Not all procedures were performed in all patients. Findings included ureteral dilation proximal to the level of an intraluminal mass and ipsilateral hydronephrosis. Unilateral ureteronephrectomy was performed in three dogs with masses in the proximal ureter; ureteral resection and anastamosis was performed in the remaining patient with a mass located in the distal ureter. The same pathologist (RAP) reviewed all four lesions. The lesions appeared polypoid and were attached to the ureteral wall by a thin stalk. Histopathologically, they contained a superficial layer of well-differentiated transitional epithelial cells overlying a prominent fibrovascular stroma with a mild (three dogs) or marked (one dog) degree of lymphoplasmacytic inflammation. This disease may represent a benign neoplasm or a chronic inflammatory reaction and has a good prognosis with surgical removal. Its histopathological characteristics, higher incidence in males, and location more commonly within the upper third of the ureter is remarkably similar to the disease in humans. 相似文献
966.
J.L. Hernandez J.G. Besso D.N. Rault A.H. Cohen A. Guionnet D. Begon Y. Ruel 《Veterinary radiology & ultrasound》2003,44(2):196-198
An 8-year-old intact female West Highland White Terrier was examined for anorexia, vomiting, abdominal distension, and mild purulent vulvar discharge. The results of physical examination, laboratory testing, and radiography are presented. Emphysematous pyometra was suspected and confirmed at surgery. Clostridium perfringens was isolated from the uterine lumen. A brief discussion of emphysematous pyometra is presented. 相似文献
967.
From 1978 to 1983, 411 bird submissions consisting of 911 birds were received in our laboratory for diagnosis. Filariasis occurred in four submissions (0.97% of total) consisting of four birds (0.44% of total), and microfilariasis was diagnosed in 34 submissions (8.27% of total) consisting of 123 birds (13.5% of total). Adult filariae were found in the abdominal air sacs of two cockatoos and two red lories and identified as Cardiofilaria sp. Although filariasis and microfilariasis in birds are found world-wide, there seems to have been no report made previously in Indonesia. 相似文献
968.
969.
Economic loss from transmissible gastroenteritis (TGE) was estimated at $0.18 per hog marketed for the average Missouri Mail-in-Record swine panel producer in 1978. This cost was $0.19 per hog marketed in 1979. These estimates were averaged for all producers in the record system, those with TGE in their herds as well as TGE-free herds. Estimates were also prepared for those herds with TGE outbreaks. In 1978, the average loss due to TGE for producers who had the disease on their farms was estimated at $1.74 per hog marketed, or 18% of the average return earned above total production costs. In 1979, this cost was $1.25 per hog marketed, or 13% of the average return earned above total production costs. 相似文献
970.
Angkanaporn K. Ravindran V. Mollah Y. Bryden W.L. 《Veterinary research communications》1997,21(3):161-167
Angkanaporn, K., Ravindran, V., Mollah, Y. and Bryden, W.L., 1997. Secretion of homoarginine into the gut of chickens. Veterinary Research Communications, 21(3), 161-167A technique, based on the homoarginine present in guanidinated proteins, has been used to distinguish between endogenous secretions and exogenous dietary amino acids in the ileal digesta of monogastric animals. This technique assumes that the ingested homoarginine is not recycled into the small intestine after absorption, but this assumption is yet to be experimentally validated in chickens. The secretion of homoarginine into the gut of broilers that were intravenously infused with 20 and 40 mmol/L homoarginine solutions was assessed. The plasma concentrations of homoarginine increased with increasing concentrations of homoarginine infused. However, only negligible levels of homoarginine (7.0 to 45.2 µg/g dry matter) were found in the digesta. Less than 0.01% of the intravenously infused homoarginine was recovered in the intestinal digesta, indicating that the secretion of homoarginine into the gut of chickens was insignificant. 相似文献