首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   83714篇
  免费   4726篇
  国内免费   56篇
林业   2943篇
农学   2285篇
基础科学   564篇
  9197篇
综合类   14874篇
农作物   3087篇
水产渔业   3913篇
畜牧兽医   45688篇
园艺   880篇
植物保护   5065篇
  2018年   1035篇
  2017年   1173篇
  2016年   1086篇
  2015年   941篇
  2014年   1175篇
  2013年   3056篇
  2012年   2124篇
  2011年   2704篇
  2010年   1656篇
  2009年   1759篇
  2008年   2595篇
  2007年   2412篇
  2006年   2406篇
  2005年   2127篇
  2004年   2093篇
  2003年   2083篇
  2002年   1973篇
  2001年   2706篇
  2000年   2809篇
  1999年   2133篇
  1998年   814篇
  1997年   823篇
  1996年   807篇
  1995年   1017篇
  1994年   888篇
  1993年   842篇
  1992年   1931篇
  1991年   2080篇
  1990年   1925篇
  1989年   1934篇
  1988年   1824篇
  1987年   1930篇
  1986年   1975篇
  1985年   1873篇
  1984年   1481篇
  1983年   1298篇
  1982年   880篇
  1979年   1367篇
  1978年   1122篇
  1977年   973篇
  1976年   937篇
  1975年   983篇
  1974年   1272篇
  1973年   1300篇
  1972年   1234篇
  1971年   1147篇
  1970年   1088篇
  1969年   964篇
  1968年   832篇
  1967年   869篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
A captive female square‐lipped rhinoceros born in 1993 had been showing intermittent signs of bilateral conjunctivitis and conjunctival proliferation since 1998. Periodic improvement was noted, especially in winter, but overall the condition had deteriorated over the years. Treatment with various topical, intralesional, and systemic antibiotics and glucocorticosteroids was largely ineffective, as were repeated dewormings. No primary cause for these lesions was found in biopsies taken in 2000 and 2006, although a severe infiltrate of numerous eosinophils was observed in the latter. As the condition worsened, secondary corneal changes were noted, and eventually vision was lost due to proliferative conjunctival tissue. Aggressive resection of the proliferating tissue in 2013 restored vision and submitted biopsies yielded a diagnosis of severe allergic conjunctivitis, eosinophilic granuloma, and habronematid (Habronema or Draschia) larval infection. As no other rhinoceros in the herd was affected, including two calves born to the patient who were in close contact with their mother, it was concluded the presentation was most likely due to a hypersensitivity reaction to the dead or dying larvae. Fly repellent is now regularly applied around the eye of this rhinoceros, and a protective face mask has been fitted. Ongoing periodic relapses are treated with oral ivermectin, topical antibiotics, and steroids.  相似文献   
993.
994.
Five cases of canine keratomycosis were diagnosed and treated at a private Veterinary Ophthalmology Practice in Melbourne, Australia. Clinical presentations varied between dogs. Predisposing factors were identified in 4 of 5 cases. Diagnostic modalities utilized were corneal cytology and fungal culture. Corneal cytology confirmed the presence of fungal organisms in all five cases. Aspergillus, Scedosporium, and Candida were cultured from three cases, respectively. Specific antifungal treatment included 1% voriconazole solution or 1% itraconazole ointment. Keratectomy and conjunctival grafting surgery was performed in two patients. Resolution of infection and preservation of vision were achieved in 4 of 5 patients.  相似文献   
995.
Cisplatin is a platinum‐containing cytotoxic drug indicated for the treatment of solid tumors in veterinary and human patients. Several of the algorithms used to standardize the doses of cytotoxic drugs utilize allometry, or the nonproportional relationships between anatomical and physiological variables, but the underlying basis for these relationships is poorly understood. The objective of this proof of concept study was to determine whether allometric equations explain the relationships between body weight, kidney weight, renal physiology, and clearance of a model, renally cleared anticancer agent in dogs. Postmortem body, kidney, and heart weights were collected from 364 dogs (127 juveniles and 237 adults, including 51 dogs ≥ 8 years of age). Renal physiological and cisplatin pharmacokinetic studies were conducted in ten intact male dogs including two juvenile and eight adult dogs (4–55 kg). Glomerular filtration rate (GFR), effective renal plasma flow, effective renal blood flow, renal cisplatin clearance, and total cisplatin clearance were allometrically related to body weight with powers of 0.75, 0.59, 0.61, 0.71, and 0.70, respectively. The similar values of these diverse mass exponents suggest a common underlying basis for the allometry of kidney size, renal physiology, and renal drug handling.  相似文献   
996.
997.
Nanotechnology applications in medicine have seen a tremendous growth in the past decade and are being employed to enhance the stability and bioavailability of lipophilic substances, such as florfenicol. This study aimed to examine the pharmacokinetic properties of the formulated oil‐in‐water florfenicol‐loaded nanoemulsion (FF‐NE). FF‐NE and florfenicol control (Nuflor®) were administered to the pigs at a dose of 20 mg/kg. Nanoemulsion formulation of florfenicol was highly influenced in vivo plasma profile. The in vivo absorption study in pigs indicated that Cmax (14.54 μg/mL) was significantly higher in FF‐NE, 3.42 times higher than the marketed formulation. In comparison with the control group, the relative bioavailability of formulated nanoemulsion was up to 134.5%. Assessment of bioequivalence using log‐transformed data showed that the 90% confidence intervals (90% CI) of Cmax and AUC0–∞ were 2.48–4.60 and 1.21–1.72, respectively.  相似文献   
998.
999.
1. The aim of this study was to evaluate the occurrence of Campylobacter spp. in domestic and free-living pigeons and to evaluate the antibiotic resistance profiles.

2. The material consisted of cloacal swabs obtained from 108 homing pigeons and fresh faeces from 72 wild birds from Lublin and its vicinity. The identification of strains isolated on differential/selective media for Campylobacter spp. was carried out by MALDI-TOF and PCR. The susceptibility to antibiotics was evaluated by minimum inhibitory concentration (MIC) in Mueller-Hinton broth.

3. A total of 35 strains of Campylobacter spp. were isolated; 27 were identified as Campylobacter jejuni and 8 as Campylobacter coli. Over half of the isolates were resistant to erythromycin and streptomycin, 40% of strains were resistant to tetracycline and ampicillin and 37% isolates were resistant to amoxicillin. Resistance to two or more antibiotics was observed in all strains tested.

4. The results indicate that both domestic and free-living pigeons are reservoirs for bacteria of the genus Campylobacter, which are characterised by varied and growing resistance to commonly used antibiotics.  相似文献   

1000.
Pacemakers were implanted in 4 client-owned female dogs which had persistent atrial standstill. Three dogs were alive after 14 to 39 months and 1 dog was euthanized after 10.5 years. This report demonstrates that some dogs with persistent atrial standstill can survive for extended time periods.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号