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   7287篇
  免费   355篇
  国内免费   6篇
林业   491篇
农学   155篇
基础科学   38篇
  1368篇
综合类   1273篇
农作物   238篇
水产渔业   558篇
畜牧兽医   2807篇
园艺   203篇
植物保护   517篇
  2023年   61篇
  2022年   73篇
  2021年   152篇
  2020年   155篇
  2019年   184篇
  2018年   181篇
  2017年   152篇
  2016年   182篇
  2015年   162篇
  2014年   190篇
  2013年   276篇
  2012年   483篇
  2011年   608篇
  2010年   304篇
  2009年   245篇
  2008年   499篇
  2007年   527篇
  2006年   469篇
  2005年   436篇
  2004年   417篇
  2003年   384篇
  2002年   395篇
  2001年   72篇
  2000年   55篇
  1999年   71篇
  1998年   54篇
  1997年   53篇
  1996年   43篇
  1995年   50篇
  1994年   48篇
  1993年   44篇
  1992年   34篇
  1991年   38篇
  1990年   35篇
  1989年   43篇
  1988年   33篇
  1987年   28篇
  1986年   29篇
  1985年   40篇
  1984年   28篇
  1983年   31篇
  1982年   22篇
  1981年   17篇
  1980年   26篇
  1979年   25篇
  1978年   15篇
  1977年   18篇
  1975年   14篇
  1973年   22篇
  1970年   12篇
排序方式: 共有7648条查询结果,搜索用时 365 毫秒
211.
212.
A stainless steel, grooved rack was designed to handle large numbers of coverslips used in cell cultures. The rack separated and held the coverslips through the washing process and subsequent manipulations. Slips washed by this method allowed consistently good cell sheets to grow with no signs of cytotoxicity to the cultures.  相似文献   
213.
214.
A survey of sheep dipping in Scotland in 1978 showed that about 42 tonnes of organophosphorus and 17 tonnes of organochlorine insecticides were used to control ectoparasites. Information is presented about their pattern of use and about the disposal of surplus sheep dip and the empty containers. Six river pollution incidents involving sheep dips in 1978 are recorded. The main geographical areas affected by headfly (Hydrotaea irritans Fall.) and the measures taken against them are noted.  相似文献   
215.
Benzimidazole and its 2-amino analogue were non-toxic to Lumbricus terrestris when administered orally. The fungicidal 2-substituted benzimidazoles (benomyl, carben-dazim, fuberidazole and thiabendazole) and l-(benzimidazol-2-yl)-3-butylurea were highly and equally toxic. The equitoxicity of compounds with widely differing substituent groups suggests a common mode of action—the benzimidazole moiety being the active part of the molecule. It is likely that there is a common mode of action for benzimidazole analogues for both fungicidal activity and earthworm toxicity. There was no detectable effect on the cholinesterase levels of earthworms poisoned by benomyl. But it is confirmed that the cholinesterase inhibitory activity of benomyl in vitro is due to formation of butyl isocyanate.  相似文献   
216.
Fractionation and reconstitution techniques were used to study the contribution of endogenous flour lipids to the quality of semisweet (Rich Tea-type) biscuits. Biscuit flour was defatted with chloroform and baked with bakery fat but without endogenous lipid addition. Semisweet biscuits baked from defatted flour were flatter, denser, and harder and showed collapse of gas cells during baking when compared with control biscuits. Defatted flour semisweet doughs exhibited a different rheological behavior from the control samples showing higher storage and loss moduli (G' and G' ' values), that is, high viscoelasticity. Functionality was restored when total nonstarch flour lipids were added back to defatted flour. Both the polar and nonpolar lipid fractions had positive effects in restoring flour quality, but the polar lipid fraction was of greatest benefit. Both fractions were needed for complete restoration of both biscuit quality and dough rheological characteristics.  相似文献   
217.
218.
Three dogs and 1 cat with intranasal tumors were treated with pyropheophorbide-a-hexyl ether-based photodynamic therapy (PDT). PDT was well tolerated by all the animals, and no adverse effects from photosensitizer injection, such as cutaneous photosensitization, were observed. Facial swelling was observed in all animals after each PDT treatment but resolved spontaneously within 72 hours after treatment. All animals had a decrease in severity of epistaxis, frequency of sneezing, and amount of nasal discharge after PDT. Clinical signs were controlled for variable time, although long-term responses were comparable with radiation therapy in 2 animals. This small case series demonstrates another application for PDT in veterinary medicine. On the basis of these findings. further studies are warranted to define the role of PDT in the management of intranasal tumors in dogs and cats.  相似文献   
219.
The combined occurrence of ocular pigment deposition and glaucoma has been described in Cairn Terriers. Recently, this condition was also observed in two other breeds: the Boxer (two cases) and the Labrador Retriever (one case). Six dogs were referred to the Ophthalmology section of the Department of Clinical Sciences of Companion Animals and to a private referral clinic because of glaucoma or blindness in one or both eyes. In five cases ophthalmic examination showed pigment depositions in the sclera around the entire circumference of the perilimbal zone. Eight enucleated eyes (four eyes of two Cairn Terriers, three eyes of two Boxers and one eye of a Labrador Retriever) were examined microscopically. All eyes showed the same findings: an extensive infiltration of large melanin-containing cells with an eccentric nucleus, located in the iris, ciliary body, retina, choroids and sclera. Transmission electron microscopy of two of the examined eyes revealed that the morphology of most of these cells was consistent with melanophages. While reports in the veterinary literature concerning this condition are limited the cells concerned have been described to be melanocytes. Further research is needed to conclusively identify the cell type. As described in the present report, the histologic and transmission electron microscopic findings suggest a different etiology of the ocular pigment deposition and glaucoma compared with the pigment dispersal syndrome in humans.  相似文献   
220.
A combination vaccine (Bovi-Shield FP4 + L5, Pfizer Animal Health) containing modified-live virus (MLV) components against bovine herpesvirus-1 (BHV-1), bovine viral diarrhea virus BVDV), parainfluenza virus-3 (PI3), bovine respiratory syncytial virus (BRSV), and inactivated cultures of Leptospira canicola, grippotyphosa, hardjo, icterohaemorrhagiae, and pomona was evaluated for safety in pregnant beef and dairy animals. Heifers vaccinated prebreeding with the minimum immunizing dose (lowest antigen level initiating immunizing effects) of the vaccine's MLV BHV-1 or BVDV components and during pregnancy (approximately 200 days of gestation) with vaccine containing 10x doses of the same BHV-1 and BVDV components delivered live, healthy calves that were determined to be serologically negative (titer less than 1:2) for neutralizing antibodies to BHV-1 and BVDV prior to nursing. Additionally, in three field safety studies, previously vaccinated cows and heifers that received a field dose (vaccine containing antigen levels required for commercial sale of the MLV combination vaccine during either the first, second, or third trimester of pregnancy had abortion rates similar to those of pregnant cows and heifers vaccinated during the same stage of pregnancy with sterile water diluent.  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