全文获取类型
收费全文 | 601篇 |
免费 | 39篇 |
专业分类
林业 | 11篇 |
农学 | 2篇 |
基础科学 | 1篇 |
37篇 | |
综合类 | 111篇 |
农作物 | 28篇 |
水产渔业 | 22篇 |
畜牧兽医 | 406篇 |
园艺 | 4篇 |
植物保护 | 18篇 |
出版年
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 12篇 |
2015年 | 8篇 |
2014年 | 9篇 |
2013年 | 27篇 |
2012年 | 18篇 |
2011年 | 23篇 |
2010年 | 22篇 |
2009年 | 24篇 |
2008年 | 34篇 |
2007年 | 22篇 |
2006年 | 21篇 |
2005年 | 16篇 |
2004年 | 10篇 |
2003年 | 23篇 |
2002年 | 14篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 17篇 |
1988年 | 8篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1972年 | 8篇 |
1971年 | 5篇 |
1970年 | 13篇 |
1969年 | 6篇 |
1968年 | 8篇 |
1967年 | 8篇 |
排序方式: 共有640条查询结果,搜索用时 31 毫秒
631.
Ma HT Patterson RL van Rossum DB Birnbaumer L Mikoshiba K Gill DL 《Science (New York, N.Y.)》2000,287(5458):1647-1651
The coupling mechanism between endoplasmic reticulum (ER) calcium ion (Ca2+) stores and plasma membrane (PM) store-operated channels (SOCs) is crucial to Ca2+ signaling but has eluded detection. SOCs may be functionally related to the TRP family of receptor-operated channels. Direct comparison of endogenous SOCs with stably expressed TRP3 channels in human embryonic kidney (HEK293) cells revealed that TRP3 channels differ in being store independent. However, condensed cortical F-actin prevented activation of both SOC and TRP3 channels, which suggests that ER-PM interactions underlie coupling of both channels. A cell-permeant inhibitor of inositol trisphosphate receptor (InsP3R) function, 2-aminoethoxydiphenyl borate, prevented both receptor-induced TRP3 activation and store-induced SOC activation. It is concluded that InsP3Rs mediate both SOC and TRP channel opening and that the InsP3R is essential for maintaining coupling between store emptying and physiological activation of SOCs. 相似文献
632.
We report a photoactivatable variant of the Aequorea victoria green fluorescent protein (GFP) that, after intense irradiation with 413-nanometer light, increases fluorescence 100 times when excited by 488-nanometer light and remains stable for days under aerobic conditions. These characteristics offer a new tool for exploring intracellular protein dynamics by tracking photoactivated molecules that are the only visible GFPs in the cell. Here, we use the photoactivatable GFP both as a free protein to measure protein diffusion across the nuclear envelope and as a chimera with a lysosomal membrane protein to demonstrate rapid interlysosomal membrane exchange. 相似文献
633.
The ability to visualize, track, and quantify molecules and events in living cells with high spatial and temporal resolution is essential for understanding biological systems. Only recently has it become feasible to carry out these tasks due to the advent of fluorescent protein technology. Here, we trace the development of highly visible and minimally perturbing fluorescent proteins that, together with updated fluorescent imaging techniques, are providing unprecedented insights into the movement of proteins and their interactions with cellular components in living cells. 相似文献
634.
D.P. Patterson MS S.R. Cooper PhD D.W. Freeman PhD R.G. Teeter PhD 《Journal of Equine Veterinary Science》2002,22(10)
This study examines the effect of phytase supplementation on dry matter and phosphorus digestibility in mature horses. Four mature sedentary quarter horse geldings were used in a 4 × 4 Latin square design experiment. Horses were fed at 2% of the group's average body weight. The experimental diets consisted of textured concentrate of rolled corn, oats, and soybean meal fed in a 50:50 ratio with native prairie grass hay. The treatments were as follows: (1) control (0) with no phytase added to the basal ration, (2) 300 FTU/kg added to the basal ration, (3) 600 FTU/kg added to the basal ration, and (4) 900 FTU/kg added to the basal ration. During the 72-hour collections, total urine and feces were collected. Feed samples were also collect randomly throughout the trial. Feed and fecal sample were analyzed for dry matter, phosphorus, calcium, and magnesium. Urine samples were analyzed for phosphorus, calcium, and magnesium. There was no significance difference in dry matter intake, fecal output, dry matter digestibility, and urinary output across all diets (P > .05). Phosphorus digestibility was not improved with the addition of supplemental phytase (P > .05). The failure to observe an improvement in phosphorus digestibility may be because of the high levels of phosphorus in the diets. Further research needs to be conducted using diets with lower levels of phosphorus. 相似文献
635.
Dr R. L. Stanley M. E. Mccue S. J. Valberg J. R. Mickelson I. G. Mayhew C. Mcgowan C. N. Hahn J. C. Patterson‐Kane R. J. Piercy 《Equine veterinary journal》2009,41(6):597-601
Reasons for performing study: A glycogen synthase (GYS1) mutation has been described in horses with histopathological evidence of polysaccharide storage myopathy (PSSM) in the USA. It is unknown whether the same mutation is present in horses from the UK. Objectives: To determine whether the GYS1 mutation occurs in UK horses with histopathological evidence of PSSM and exertional rhabdomyolysis. Hypothesis: The R309H GYS1 mutation is present in a variety of UK horse breeds and that the mutation is commonly associated with exertional rhabdomyolysis. Methods: DNA was extracted from 47 muscle or blood samples from UK horses with histories of exertional rhabdomyolysis in which muscle biopsy diagnosis had been pursued. The proportions of GYS1 mutation positive cases were compared among histopathologically defined groups. In addition, breeds that carried the GYS1 mutation were identified from a total of 37 grade 2 (amylase‐resistant) PSSM cases. Results: Of 47 horses with exertional rhabdomyolysis in which a muscle biopsy diagnosis was pursued, 10 (21%) carried the GYS1 mutation. The mutation was only found in horses with grade 2 PSSM (i.e. not in horses with normal, idiopathic myopathy or grade 1 PSSM biopsy samples). In total, the GYS1 mutation was found in 24/37 (65%) of grade 2 PSSM cases. A variety of breeds, including Quarter Horse, Appaloosa, Warmblood, Connemara‐cross, Cob, Polo Pony and Thoroughbred cross carried the mutation. Conclusions: The GYS1 mutation is an important cause of exertional rhabdomyolysis of UK horse breeds but does not account for all forms of PSSM. Potential relevance: Genotyping is recommended in cases of exertional rhabdomyolysis, prior to or in combination with, muscle biopsy. However a significant proportion of horses with histopathological evidence of PSSM and/or exertional rhabdomyolysis have different diseases. 相似文献
636.
Pork products are a possible source of introduction of PCV2 isolates into a pig population. However, limited work has been done on the transmission through meat of porcine circovirus type 2 (PCV2), a virus associated with several disease syndromes in pigs. The objectives of this study were to determine if pork products from PCV2-infected pigs contain PCV2 DNA/antigen and to determine if the PCV2 present in the tissues is infectious by performing in vitro and in vivo studies. Skeletal muscle, bone marrow, and lymphoid tissues from pigs experimentally inoculated with PCV2 were collected 14 days post-inoculation (DPI). The tissues were tested for presence of PCV2 DNA by quantitative real-time PCR, for PCV2 antigen by immunohistochemistry (IHC), and for presence of infectious PCV2 by virus isolation and inoculation of PCV2 naïve pigs. Lymphoid tissues contained the highest amount of PCV2 (positive by PCR, IHC, and virus isolation), bone marrow contained a lower amount of PCV2 (positive by PCR and IHC but negative by virus isolation), and skeletal muscle contained the lowest amount of PCV2 (positive by PCR but negative by IHC and virus isolation). Naïve pigs fed for three consecutive days with either skeletal muscle, bone marrow, or lymphoid tissues all became PCV2 viremic as determined by quantitative real-time PCR on serum starting at 7 DPI. The pigs also seroconverted to PCV2 as determined by PCV2 IgM and IgG ELISA. In addition, PCV2 antigen was detected by IHC stains in lymphoid tissues and intestines collected from the majority of these pigs. Results from this study indicate that uncooked PCV2 DNA positive lymphoid tissues, bone marrow, and skeletal muscle from PCV2 viremic pigs contain sufficient amount of infectious PCV2 to infect naïve pigs by the oral route. 相似文献
637.
LCG Silva CF Lúcio GAL Veiga JA Rodrigues CI Vannucchi 《Reproduction in domestic animals》2009,44(S2):160-163
This study aimed to standardize signs and diagnostic criteria of respiratory function in newborn puppies delivered normally or after dystocia and caesarean operation. A total of 48 neonates were allocated into groups: eutocia (n = 20), dystocia (n = 8), caesarean (c)-section (n = 20). Neonatal health was assessed using the Apgar score and body temperature was determined at 0, 5 and 60 min after delivery. Venous blood gases (pO2 and SO2 ) was measured immediately and 60 min after delivery, and a thoracic radiograph was made between 0 and 5 min of life. The c-section group had significantly lower Apgar scores at birth and 5 min. Hypothermia was present at 5 min in the eutocia and c-section groups, and at 60 min in all groups. The eutocia group had an irregular respiratory pattern in 78% of puppies at birth, 27.7% at 5 min and 21% at 60 min compared with 87.5%, 62.5% and 12.5% of the pups in the dystocia group where there was irregular respiratory rhythm, moderate to intense respiratory sounds with agonic episodes. The c-section group had respiratory alterations in 70%, 45% and 16% of puppies at 0, 5 and 60 min, respectively. Radiographic abnormalities were present in 17% of the pups in the eutocia group, 25% of the pups in the dystocia group and 30% of the pups in the c-section group, respectively. The c-section group had significantly lower SO2 values at 60 min than at birth. All puppies had hypoxaemia, but a significant decrease was observed in the c-section group. Newborn puppies had tissue hypoxia and irregular respiratory pattern at birth. Caesarean-section puppies had lower vitality; however, all developed satisfactory Apgar scores at 5 min of life, regardless of the obstetric condition. 相似文献
638.
JC Monteiro JSA Gonçalves JA Rodrigues CF Lúcio LCG Silva MEOA Assumpção CI Vannucchi 《Reproduction in domestic animals》2009,44(S2):359-362
Poor sperm viability post-thaw has resulted in constant research into methods of cryopreservation of canine semen. One factor that may be involved in poor viability is sperm oxidative stress caused by excessive formation of reactive oxygen species. The present study was performed in order to evaluate the effect of different concentrations of ascorbic acid (AA) and glutathione (Glu) added to an extender for the freeze-thawing of dog sperm. Semen from five mature dogs was collected and frozen in two studies. Prior to and after freezing, sperm motility, morphology and membrane status were examined. In addition, sperm motility was examined up to 120 min after thawing to evaluate thermo-resistance. In study I, semen was collected twice from each dog. On both occasions, semen was divided into three aliquots: control, Glu 1 m m and Glu 5 m m . In study II, semen was collected twice and divided into three aliquots; control, AA 50 μ m and AA 250 μ m . Initial sperm motility was significantly higher in sperm diluted with AA 50 μ m ; sperm longevity, however, measured by a thermal-resistance test (TRT), was higher for Glu treatments. Higher concentration of Glu produced significant improvement in TRT and membrane status, whereas higher concentration of AA had a negative impact in sperm longevity. Antioxidant supplementation to semen freezing extenders improved semen quality post-thaw. Moreover, Glu had the most beneficial effect when supplemented at 5 m m . 相似文献
639.
M D'Angelo JA Visintin LJ Richtzenhain RF Gonçalves 《Reproduction in domestic animals》2009,44(3):536-539
The aim of this study was to evaluate the efficiency of trypsin treatment on the inactivation of bovine herpesvirus type 1 (BoHV-1) on in vitro produced by fertilization and artificially infected bovine embryos. Bovine embryos on day 7 were exposed with 10 μl of BoHV-1, Los Angeles strain 107.5 TCID. These embryos and control embryos were divided in two groups: submitted to the sequential washes or to the trypsin treatment according to the International Embryo Transfer Society (IETS) guidelines. The embryos and the last washing drop of each group were used as inoculum to infect Madin Darby bovine kidney (MDBK) cells and submitted to nested PCR reaction using the primer that encodes the gene conserved region of virus glycoprotein gB. The data have shown that the control embryos and their last washing drop were negative. The exposed embryos that were treated with trypsin have shown positive results on the n-PCR and MDBK culture, and their last washing drop were negative. Our data have demonstrated that the trypsin treatment was not able to eliminate the BHV-1 of the embryos, suggesting an interaction between virus and embryo. 相似文献
640.
Lily Summerton Mark Greener David Patterson Colin D Brown 《Pest management science》2023,79(2):616-626