全文获取类型
收费全文 | 405篇 |
免费 | 36篇 |
专业分类
林业 | 15篇 |
农学 | 9篇 |
基础科学 | 2篇 |
42篇 | |
综合类 | 120篇 |
农作物 | 7篇 |
水产渔业 | 20篇 |
畜牧兽医 | 202篇 |
园艺 | 4篇 |
植物保护 | 20篇 |
出版年
2021年 | 8篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 9篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 15篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 14篇 |
2005年 | 12篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 11篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1980年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1972年 | 9篇 |
1971年 | 5篇 |
1970年 | 8篇 |
1969年 | 3篇 |
1968年 | 6篇 |
1967年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有441条查询结果,搜索用时 93 毫秒
31.
Abtahian F Guerriero A Sebzda E Lu MM Zhou R Mocsai A Myers EE Huang B Jackson DG Ferrari VA Tybulewicz V Lowell CA Lepore JJ Koretzky GA Kahn ML 《Science (New York, N.Y.)》2003,299(5604):247-251
Lymphatic vessels develop from specialized endothelial cells in preexisting blood vessels, but the molecular signals that regulate this separation are unknown. Here we identify a failure to separate emerging lymphatic vessels from blood vessels in mice lacking the hematopoietic signaling protein SLP-76 or Syk. Blood-lymphatic connections lead to embryonic hemorrhage and arteriovenous shunting. Expression of slp-76 could not be detected in endothelial cells, and blood-filled lymphatics also arose in wild-type mice reconstituted with SLP-76-deficient bone marrow. These studies reveal a hematopoietic signaling pathway required for separation of the two major vascular networks in mammals. 相似文献
32.
Myers EH 《Science (New York, N.Y.)》1933,77(2008):609-610
33.
34.
Wohlmuth H Leach DN Smith MK Myers SP 《Journal of agricultural and food chemistry》2005,53(14):5772-5778
Ginger (Zingiber officinale Roscoe), a monocotyledonous, sterile cultigen, is widely used as a spice, flavoring agent, and herbal medicine. The pungency of fresh ginger is due to a series of homologous phenolic ketones of which [6]-gingerol is the major one. The gingerols are thermally unstable and can be converted to their corresponding shogaols, which are present in dried ginger. Fresh rhizomes of 17 clones of Australian ginger, including commercial cultivars and experimental tetraploid clones, were assayed by HPLC for gingerols and shogaols. [6]-Gingerol was identified as the major pungent phenolic compound in all samples, while [8]- and [10]-gingerol occurred in lower concentrations. One cultivar known as "Jamaican" contained the highest concentrations of all three gingerols and was the most pungent of the clones analyzed. Gingerols were stable in ethanolic solution over a 5-month period when stored at 4 degrees C. Shogaols were not identified in the extracts prepared from fresh rhizomes at ambient temperature, confirming that these compounds are not native constituents of fresh ginger. In contrast to previous findings, this study did not find significant differences in gingerol concentrations between the tetraploid clones and their parent diploid cultivar. 相似文献
35.
The selective toxicity of new N-phosphorothioyl-carbamate esters 总被引:4,自引:0,他引:4
M A Fahmy T R Fukuto R O Myers R B March 《Journal of agricultural and food chemistry》1970,18(5):793-796
36.
R. L. Grier G. Di Guardo R. Myers D. F. Merkley 《The Journal of small animal practice》1995,36(9):385-388
Distilled water was studied as an hypoosmotic oncolysis agent to prevent mast cell tumour (MCT) recurrence following surgical excision. The results from 118 MCTS excised in 74 dogs were: surgery alone, a recurrence rate of 52·6 per cent (10/19); and surgery followed by distilled water injections into the wound, a 26·2 per cent (26/99) recurrence rate. All of 10 small MCTS (0·03 to 0·25 cm3) injected with distilled water in situ with no surgery, regressed. The present data suggest that distilled water should be considered as an adjunct to surgery for canine MCTS. 相似文献
37.
Ten foals of various breeds were deprived of colostrum from birth to 36 hours of age, then were allotted to 2 groups. Foals of group 1 (n = 6) were given 20 g (200 ml) of purified equine IgG IV in a 10% solution, and foals of group 2 (n = 4) were given 30 g (300 ml) of the same preparation. Total administration time for each 10 g of IgG in 100 ml was approximately 10 minutes. Serum IgG concentration in foals was assessed prior to, between 24 and 48 hours, and at 7 and 14 days after IgG administration. Between 24 and 48 hours after IgG administration, mean serum IgG concentration in group-1 foals was 425 mg/dl (range, 350 to 480 mg/dl). Mean body weight for this group of foals was 50.3 kg (range, 43.3 to 54.7 kg). For group-2 foals, mean serum IgG concentration was 768 mg/dl (range, 640 to 920 mg/dl) between 24 and 48 hours after administration of IgG. Foals of this group had mean body weight of 43.2 kg (range, 36.5 to 47.5 kg). Serum IgG concentration in group-2 foals at 24 to 48 hours was significantly (P = 0.005) greater than that in group-1 foals. Mean total IgG recovery at 24 to 48 hours, calculated on the basis of 94.5 ml of plasma volume/kg of body weight, was approximately 100%. Values of IgG measured in all foals 1 and 2 weeks after administration of the IgG concentrate were equivalent to values expected after normal decay of passively acquired IgG.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
38.
39.
Endogenous opioid suppression of release of luteinizing hormone during suckling in postpartum anestrous beef cows 总被引:1,自引:0,他引:1
Beef cows were used to determine if suckling influences release of LH via endogenous opioids at 28 +/- 4 d after parturition. Cows of similar weight and body condition (6.8 +/- .1, 1 = emaciated, 9 = obese) were assigned randomly to five groups (n = 6 to 7): 1) control-suckled/saline (suckled 15 min every 6 hr for 48 hr); 2) control-suckled/naloxone; 3) calf-removal/saline (calf removal for 52 hr); 4) calf-removal/naloxone; and 5) control-suckled/GnRH (Gonadotropin-Releasing Hormone). At 0 hr, saline was administered to all cows. This treatment was continued at 6 hr intervals for 24 hr. Either naloxone (0.5 mg/kg), GnRH (40 ng/kg) or saline was administered to cows in their respective groups every 6 hr during the ensuing 24-hr period in calf-removal groups, or immediately preceding each suckling episode in the control-suckled groups. Blood samples for analysis of luteinizing hormone (LH) were collected at 15-min intervals for 1 hr prior to and 3 hr after treatment at 0, 24, 36 and 48 hr. Cows were observed for estrus twice daily. All cows in the control-suckled/GnRH group released LH (P less than .05) in response to exogenous GnRH, indicating the presence of releasable quantities of the gonadotropin. Mean concentrations of LH were not effected (P greater than .05) by the control-suckled regime. However, calf-removal alone, or in combination with naloxone, increased (P less than .05) mean concentrations of LH by 48 hr.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
40.
Norman Myers 《Forest Ecology and Management》1983,6(1):59-79
Tropical moist forests (TMFs) are undergoing three principal types of exploitation — commercial logging, large-scale ranching and small-scale cultivation — that generally amount to unsustainable use. These modes of exploitation, or rather over-exploitation, focus on only a very few of the many products available from the forest ecosystems, resulting in degradation if not destruction for the rest. Through systematic screening of raw materials such as phytochemicals and genetic resources for industry, agriculture, and medicine, we could make expanded use of tropical forests — and the harvesting of these low-volume products need cause little disruption of forest ecosystems. Moreover, tropical forests offer many environmental services, whose value is increasingly apparent as deforestation proceeds. A comprehensive development strategy is required if we are to make best use of these forests, with a shift in emphasis from short-term, narrow-interest exploitation of a few products, to long-term, broad-scale utilization of whatever goods and services can be made available without degradation of the ecosystem. 相似文献