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   67739篇
  免费   6769篇
  国内免费   116篇
耳鼻咽喉   630篇
儿科学   1734篇
妇产科学   1403篇
基础医学   9197篇
口腔科学   1583篇
临床医学   8368篇
内科学   13398篇
皮肤病学   1011篇
神经病学   5597篇
特种医学   2698篇
外国民族医学   1篇
外科学   10032篇
综合类   1332篇
一般理论   75篇
预防医学   6915篇
眼科学   1419篇
药学   5246篇
中国医学   98篇
肿瘤学   3887篇
  2022年   592篇
  2021年   1588篇
  2020年   858篇
  2019年   1497篇
  2018年   1662篇
  2017年   1190篇
  2016年   1303篇
  2015年   1514篇
  2014年   2141篇
  2013年   2703篇
  2012年   4181篇
  2011年   4218篇
  2010年   2266篇
  2009年   2144篇
  2008年   3500篇
  2007年   3569篇
  2006年   3366篇
  2005年   3188篇
  2004年   2843篇
  2003年   2647篇
  2002年   2428篇
  2001年   1648篇
  2000年   1543篇
  1999年   1524篇
  1998年   685篇
  1997年   529篇
  1996年   505篇
  1995年   503篇
  1994年   452篇
  1993年   488篇
  1992年   1223篇
  1991年   1139篇
  1990年   1080篇
  1989年   1057篇
  1988年   983篇
  1987年   972篇
  1986年   989篇
  1985年   911篇
  1984年   780篇
  1983年   646篇
  1982年   433篇
  1981年   355篇
  1979年   595篇
  1978年   489篇
  1977年   371篇
  1976年   383篇
  1974年   434篇
  1973年   401篇
  1972年   387篇
  1969年   360篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The effects of d-amphetamine over a wide range of doses (0.125–4.0 mg/kg IP) on rat unconditioned behaviour were examined in the presence of food and water (experiment 1), in their absence (experiment 2) and after microinjection (2.0 g in 0.5 l) directly into the striatum (experiment 3). In experiment 1 very low doses (0.125 and 0.25 mg/kg) stimulated the intake of food, but not water, and higher doses produced locomotor hyperactivity, rearing, stereotyped sniffing and anorexia. In experiment 2 all doses, including very low doses (0.125 and 0.25 mg/kg), significantly potentiated locomotor activity. In experiment 3, microinjection into the corpus striatum elicited substantial feeding, but not drinking, locomotor activity or stereotyped behaviour. The results suggest that a single graded facilitative mechanism underlies the effects on food intake and other behavioural effects of amphetamine, as implied by a general hypothesis of amphetamine action proposed in the literature, and that these effects may to a large extent by mediated by forebrain dopamine systems.  相似文献   
992.
Summary Behavioural studies were carried out to determine whether central cholinergic mechanisms regulate dopaminergic activity by presynaptic mechanisms as suggested by recentin vitro studies. Bilateral injections of a muscarinic receptor agonist, oxotremorine (4g), into the nucleus accumbens were found to enhance dopamine-induced locomotor activity. In rats deprived of presynaptic terminals by pretreatment with intraaccumbens injections of 6-hydroxydopamine, oxotremorine did not enhance dopamine-induced locomotor activity but on the contrary produced a marked reduction of locomotor activity. Although dopamine induced locomotor activity could occur in 6-hydroxydopamine treated animals, the muscarinic regulation was dependent on the presence of the intact dopamine terminal and hence a presynaptic receptor may be involved.  相似文献   
993.
994.
The effect of surgery, postoperative combination chemotherapy and postoperative radiotherapy was evaluated in subcutaneously implanted Wistar/Furth rat Wilms' tumor. Four groups were studied. Group A (controls, no treatment given) had a median survival of 44 days. Group B (surgical excision of the primary tumor on day 14 after implantation) showed a median survival of 77 days, with 40% tumor-free long-term survivors (sacrificed on day 175). Group C (excision followed by chemotherapy consisting of vincristine, actinomycin D and adriamycin) had a median survival of 61 days with 35% tumor-free long-term survivors. Group D received the same postoperative chemotherapy as well as radiotherapy and had 55% tumor-free long-term survivors. This tumor may serve as a treatment model for some human Wilms' tumor cases who do not respond well to current therapies.  相似文献   
995.
T lymphocytes in patients with Down's syndrome.   总被引:1,自引:0,他引:1  
Individuals with Down's syndrome (DS) are thought to have abnormalities in their immune system, and a tendency to infection and malignancy. Studies to quantify the number of T lymphocytes in the peripheral blood of 82 unselected institutionalized patients (50 DS, 27 controls matched for sex and age, 2 chronic lymphocytic leukemic, 2 acute leukemic, and 1 Hodgkin's disease) were conducted. The numbers of circulating T cells in DS patients did not differ significantly from the control group, and were in the upper limits of normality. Number of "avid" T cells, however, were significantly higher in the DS than in the control group. The blastogenic response of the T cells to mitogen was significantly depressed. The data did not exclude the existence of qualitative abnormalities. Except for DS patients with congenital heart disease, those older than 15 years were not more prone to upper respiratory infections than other institutionalized mentally retarded patients.  相似文献   
996.
997.
998.
999.
Several samples of commercial grade honey collected from different parts of Tennessee during the summer of 1973 were analyzed for chlorinated hydrocarbon insecticide (CHI) residues. A Modified Mill's Procedure was used to cleanup the samples prior to gas Chromatographic analysis using electron capture (EC) detection. The presence of CHI residues was confirmed by analysis on three different columns of widely varying polarity. Most of the samples contained CHI residues at 0.01—0.30 parts per billion (ppb) level. Beeswax produced during the same season contained several times higher levels of the residue than the honey samples. Recoveries of CHI residues varied from 81–95 percent by the procedure employed.  相似文献   
1000.
The ophthalmic literature dealing with diseases of the optic nerve, the optic tracts, and the visual cortex was reviewed for the period November 1975 through November 1976. Twenty-nine papers on topics of interest to optometrists were abstracted. The main areas of interest include: papilledema and optic atrophy (with ophthalmoscopic signs of both optic atrophy and papilledema); giant-cell arteritis; papillitis; interesting malformations of the face, palate, and orbital position that occur in conjunction with microphthalmus, situs inversus, and hypoplasia and aplasia of the optic nerve; the proposed association of myopia with unusual eyebrows; myelinated nerve fibers at the nerve head; pigment anomalies; the continuing discussion of nerve-head blood supply; an unexpected cause for nerve-head neovascularization; the importance of the swinging-flashlight test in the diagnosis of glaucoma; an unusual type of glaucomatous cupping; doubts about the peripapillary "halo" as a sign of glaucoma; new uses for old field tests; and new methods of ocular photography.  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