全文获取类型
收费全文 | 1619篇 |
免费 | 68篇 |
国内免费 | 2篇 |
专业分类
林业 | 145篇 |
农学 | 60篇 |
基础科学 | 4篇 |
270篇 | |
综合类 | 73篇 |
农作物 | 50篇 |
水产渔业 | 238篇 |
畜牧兽医 | 723篇 |
园艺 | 20篇 |
植物保护 | 106篇 |
出版年
2023年 | 3篇 |
2022年 | 13篇 |
2021年 | 55篇 |
2020年 | 27篇 |
2019年 | 19篇 |
2018年 | 34篇 |
2017年 | 45篇 |
2016年 | 49篇 |
2015年 | 75篇 |
2014年 | 74篇 |
2013年 | 148篇 |
2012年 | 114篇 |
2011年 | 125篇 |
2010年 | 39篇 |
2009年 | 72篇 |
2008年 | 116篇 |
2007年 | 108篇 |
2006年 | 95篇 |
2005年 | 97篇 |
2004年 | 94篇 |
2003年 | 84篇 |
2002年 | 63篇 |
2001年 | 38篇 |
2000年 | 30篇 |
1999年 | 12篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1965年 | 1篇 |
1953年 | 1篇 |
排序方式: 共有1689条查询结果,搜索用时 15 毫秒
31.
32.
Shibata I Okuda Y Yazawa S Ono M Sasaki T Itagaki M Nakajima N Okabe Y Hidejima I 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(3):405-408
Porcine circovirus type 2 (PCV2) shedding patterns were investigated by polymerase chain reaction (PCR) for the detection of PCV2 DNA, and the diagnostic suitability of a sample for the PCR was examined by using different types of samples. In the experimental infection, sixteen pigs were inoculated intranasally with PCV2. The samples, including oropharyngeal and nasal swabs, feces, whole blood and serum became positive for PCV2 DNA by PCR immediately after the inoculation, and almost all samples remained positive during the observation period, post-inoculation-day 70. Field samples were collected from 313 pigs in five different age groups. The overall percentages of positive samples in the whole blood, nasal swabs, and feces detected by PCR were 30.4%, 19.2%, and 20.4%, respectively. The frequency of positive samples increased after the nursery stages and reached a peak in the 3 to 4-month-old pigs. These results indicate that PCV2 infection may occur after weaning, that PCV2 DNA may be present in whole blood for a long period after infection, and that whole blood and serum are the most suitable sample types for the PCR analysis of PCV2. 相似文献
33.
Shimokawa T Yamagiwa D Hondo E Nishiwaki S Kiso Y Makita T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(3):423-426
To accumulate histological information of cetaceans, the proper gastric gland of Minke whales was examined by light and electron microscopic observation. A small number of mucous neck cells and a large number of chief and parietal cells were observed in the gland. At the body to basal portions of the gland, the ratio of chief cells to other cells seemed to be large compared to the neck portion. Transmission electron microscopy revealed that the chief cell had secretory granules with middle level of electron density, and that the parietal cell contained abundant mitochondria and intracellular canaliculi. The proper gastric gland of the Minke whales may appear to secrete large amounts of digestive enzymes and have high digestive activity. 相似文献
34.
Ishikawa A Sakamoto H Katagiri S Takahashi Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(1):99-102
The longitudinal changes in fecal steroid hormone concentrations and sexual behavior in 2 mated/pregnant and 3 non-mated female Hokkaido brown bears were investigated during the breeding season. Behavioral estrus (standing) lasted for 14 and 32 days in the mated females and for 25 to 36 days in the non-mated females. In non-mated females, sexual behavior, such as female-female mounting and masturbation, was observed for several days before and after the estrous period. In mated females, mean fecal estradiol-17beta concentrations were higher in the estrous period than in the post-estrous period, while fecal progesterone concentrations were higher in the post-estrous period than in the estrous period. The similar trends of steroid hormone changes were observed in the non-mated females. 相似文献
35.
El-Abasy M Motobu M Na KJ Shimura K Nakamura K Koge K Onodera T Hirota Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(8):865-871
The effects of oral administration of sugar cane extracts (SCE) on Eimeria tenella oocysts infection in chickens were studied with 2 different experiments. In Experiment 1, 3-week-old inbred chickens (MHC; H.B15) were inoculated into the crop with SCE (500 mg/kg/day) for 1 day or 3 consecutive days, and then challenged with E. tenella sporulated oocysts (2 x 10(4) cells/chicken). In Experiment 2, 1-week-old chickens were orally administered SCE at the same dose for 3 consecutive days, and then initially infected with E. tenella sporulated oocysts (2 x 10(3) cells/chicken). At 2 and 3 weeks of age, these chickens were immunized intravenously with the mixed antigens of sheep red blood cells (SRBC) and Brucella abortus (BA). At 4 weeks of age, chickens were challenged with E. tenella sporulated oocysts (1 x 10(5)/chicken). Challenged chickens with E. tenella oocysts showed markedly decreased body weight gain/day, severe hemorrhage and great number of shedding oocysts in feces and high lesion scores. Oral administration of SCE and initial infection with oocysts (2 x 10 (3)/chicken) resulted in a remarkable improvement in body weight gain/day, hemorrhage, the number of shedding oocysts and lesion score, compare to other infected groups. In addition, SCE-inoculated chickens with the initial infection showed a significant increase in antibody responses against SRBC and BA and also improvement in decreased relative proportions of Bu-1a(+) and CD4( )cells in cecal tonsil lymphocytes of E. tenella-challenged chickens. Cecal tissues of chickens administered SCE and initially infected with E. tenella oocysts showed lower numbers of schizonts, gametocytes and oocysts than those of infected control chickens. These results suggest that SCE have immunostimulating and protective effects against E. tenella infection in chickens. 相似文献
36.
Suzuki M Uchida K Morozumi M Hasegawa T Yanai T Nakayama H Tateyama S 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(11):1233-1239
Canine necrotizing meningoencephalitis (NME) and granulomatous meningoencephalomyelitis (GME) were compared pathologically. Gross observation exhibited lateral ventricular dilation and discoloration, malacia and/or cavitation of the cerebrum in NME. On the contrary, gross changes were milder in GME, except for occasional visible granulomatous mass formation. Histopathologically, the lesions of NME were distributed predominantly in the cerebral cortex and various degrees of inflammatory and necrotic changes were observed according to clinical stages. Besides, microscopic lesions of GME were mainly distributed in the white matter of the cerebrum, cerebellum and brainstem, which are characterized by perivascular cuffing, multiple granulomas and leptomeningeal infiltrates. Although macrophages and lymphocytes were predominant in the inflammatory lesions of both disorders, macrophages in GME transformed into epithelioid cells and exhibited more massive infiltration. Although lectin RCA-1-reactive cells were numerous in both disorders, lysozyme immunoreactive cells in NME were fewer than that in GME. Parenchymal infiltration of MAC387-positive cells was common in GME and limited in NME. The number of CD3-positive lymphocytes in the GME lesions tended to be greater than in NME, though the difference was not statistically significant. Morphological and immunohistochemical differences of the lesions, in particular, the characteristics of infiltrative macrophages may reflect these different pathogeneses of the two disorders. 相似文献
37.
Changes of receptor mRNAs for oxytocin and estrogen during the estrous cycle in rat uterus 总被引:1,自引:0,他引:1
Murata T Narita K Honda K Higuchi T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(6):707-712
Oxytocin receptor (OTR) mRNA levels increase dramatically near term and is potently stimulated by estrogen because increased OTR mRNA levels result from estrogen treatment in ovariectomized rat uterus. In this study, OTR, estrogen receptor (ER) alpha and ERbeta mRNA levels in the rat uterus during the estrous cycle were examined by quantitative RT-PCR. OTR mRNA levels during the estrous cycle began to increase on diestrus (P<0.05, vs value on estrus), reached maximal increase both in the morning (1000-1130 hr) and afternoon (1600-1630 hr) on proestrus (P<0.01, vs metestrus, diestrus and estrus) and then declined on estrus. In contrast ER alpha mRNA levels began to decrease on diestrus, reached statistical significance both in the morning and the afternoon on proestrus (P<0.01, vs metestrus, diestrus and estrus) and returned to the value of metestrus on estrus. ERbeta mRNA levels were low in the morning and the afternoon on proestrus (P<0.01, vs metestrus and estrus) and also returned to metestrus values on estrus. Treatments with estrogen for 3 days significantly decreased both ERalpha and ERbeta mRNA levels. It can be concluded from these results that during the estrous cycle, OTR mRNA levels in rat uterus predominantly increase at proestrus with a decrease in ERalpha and ERbeta mRNA levels, which is probably due to the increased estrogen levels in circulation before ovulation. 相似文献
38.
Mohamed T Oikawa S Nakada K Kurosawa T Sawamukai Y Sato H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(7):821-824
A new method for catheterization of the portal and hepatic veins in cattle by means of the over-the-wire system was investigated to maintain more reliable long-term patency of catheters. Four cattle were used to evaluate the success rate, patency and safety of the procedure. The catheters, coated by urokinase were patent as long as they were in situ. In addition, the introducer was useful to prevent the catheter from being broken. No complications developed during the10 days after the procedure. Two cows were then euthanized. Post mortem findings were minimal. The results of the study reported here are promising, the benefits are significant and there is no apparent disadvantage to its use. 相似文献
39.
Effects of propofol-sevoflurane anesthesia on the maternal and fetal hemodynamics blood gases, and uterine activity in pregnant goats 总被引:2,自引:0,他引:2
Setoyama K Shinzato T Misumi K Fujiki M Sakamoto H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(10):1075-1081
To determine the effects of propofol and sevoflurane on hemodynamics, acid-base balance and uterine activity in pregnant animals, a prospective experimental study was designed by use of ten pregnant goats. Propofol was intravenously administered at a bolus dose of 5 mg/kg and then infused a rate of 0.3 mg/kg/min for 5 min. Following the induction, the animals were incrementally inhaled 2.7 and 4.1% of end-tidal concentration of sevoflurane each for 30 min, and then recovered. The maternal and fetal heart rate (HR), arterial blood pressure (BP) and acid-base balance, the intrauterine pressure (IUP), and the uterine blood flow (UBF) were measured. Following the pre-anesthetic data, the parameters were measured 7 times throughout the anesthetic and recovering periods. The propofol infusion induced 1.37 times of HR increase and produced decrease in PO(2) and a relevant metabolic acidemia in the mother, with no effect in the fetus. Sevoflurane reduced BP in the fetus from 30 (2.7%) to 60 (4.1%) min of inhalation. The uterine contractions disappeared throughout sevoflurane inhalation, and then recurred within 15 min after the cessation of sevoflurane. Propofol injection increases HR, and induces a moderate hypoxemia and metabolic acidemia associated with the suppressed ventilation for pregnant goats, with less effect on the fetal hemodinamics. Sevoflurane causes minimal change in maternal hemodynamics, but induces significant hypotension in the fetus and reduction of uterine activity. These data may be useful in making anesthetic choices combined with analgesia for Caesarian section in goats. 相似文献
40.