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   94796篇
  免费   6155篇
  国内免费   739篇
耳鼻咽喉   1093篇
儿科学   2900篇
妇产科学   2313篇
基础医学   12745篇
口腔科学   2368篇
临床医学   7672篇
内科学   20822篇
皮肤病学   2039篇
神经病学   8702篇
特种医学   3829篇
外国民族医学   24篇
外科学   13347篇
综合类   1683篇
一般理论   47篇
预防医学   5512篇
眼科学   1538篇
药学   7714篇
  3篇
中国医学   524篇
肿瘤学   6815篇
  2022年   792篇
  2021年   1736篇
  2020年   1133篇
  2019年   1638篇
  2018年   2034篇
  2017年   1556篇
  2016年   1620篇
  2015年   1899篇
  2014年   2478篇
  2013年   3644篇
  2012年   4827篇
  2011年   5004篇
  2010年   3268篇
  2009年   2881篇
  2008年   4425篇
  2007年   4583篇
  2006年   4391篇
  2005年   4180篇
  2004年   4548篇
  2003年   4371篇
  2002年   4403篇
  2001年   3727篇
  2000年   3670篇
  1999年   2987篇
  1998年   1166篇
  1997年   935篇
  1996年   862篇
  1995年   821篇
  1994年   721篇
  1993年   700篇
  1992年   1794篇
  1991年   1766篇
  1990年   1511篇
  1989年   1453篇
  1988年   1345篇
  1987年   1200篇
  1986年   1188篇
  1985年   1043篇
  1984年   767篇
  1983年   706篇
  1982年   468篇
  1981年   385篇
  1979年   570篇
  1978年   420篇
  1977年   375篇
  1975年   433篇
  1974年   484篇
  1973年   465篇
  1972年   422篇
  1971年   397篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Evidence indicates that endogenous opioid peptides and glucocorticoids participate in the control of cardiovascular regulation during hemorrhagic shock. In the present study, we investigated a possible interaction between brain opioid peptides and adrenal corticosteroids regarding the control of arterial pressure during hemorrhage. The bleeding volumes required to lower arterial pressure to 80, 60 and 40 mmHg were studied in anesthetized sham-operated (SHAM) and adrenalectomized (ADX) rats. I.c.v. administration of 10 micrograms of naloxone resulted in a significant increase in the bleeding volume required to lower arterial pressure from 60 to 40 mmHg in SHAM animals, whereas no effect of naloxone was observed in ADX animals. Replacement therapy with a 100% corticosterone pellet (100 mg, s.c.), but not with a 12.5% corticosterone pellet (12.5 mg corticosterone and 87.5 mg cholesterol, s.c.), resulted in an effect of naloxone on the bleeding volume in ADX animals. The effect of replacement therapy could be inhibited by i.c.v. pretreatment with the synthetic glucocorticoid receptor antagonist, RU38486 (100 ng). These data suggest that (1) opioid mechanisms are involved in the regulation of blood pressure during hemorrhage, and (2) occupancy of glucocorticoid receptors is required for naloxone to exert its hemodynamic effect during hemorrhagic hypotension in ADX rats.  相似文献   
62.
Rat brain hippocampal slices were incubated with or without the convulsant 4-aminopyridine (4-AP). From these slices a crude mitochondrial/synaptosomal membrane fraction was prepared and analyzed for endogenous protein phosphorylation. 4-AP (10(-5) M) stimulated the phosphorylation of a 50 kDa protein by 86%. The phosphorylation of this 50 kDa protein is Ca2+/calmodulin-dependent and we suggest that this protein is the lower molecular weight subunit of Ca2+/calmodulin-dependent protein kinase II (CaMK II).  相似文献   
63.
A longitudinal survey (February 1984 - January 1985) on the incidence of acute diarrhea episodes in a sample of 8,164 children (aged 0–12 years) living in southeastern Sicily was carried out by means of weekly telephone interviews with doctors practising in the territory. The incidence rate was 0.479 (0.472–0.485 95% C.I.) per child per year and the frequency of episodes was significantly higher (p < 0.001) in children aged 0–4 years (0.86). Diarrhea was more frequent in industrial areas than in rural ones, and almost half (45.1%) of the total episodes had a mild course. No death from diarrhea occurred and admission to hospital was reported for 8.4% of all cases.Corresponding author.  相似文献   
64.
目的:探讨周围血管损伤自全大隐静脉移植治疗的方法。适应证和治疗效果。方法:回顾性分析22例周围血管损伤自体大隐静脉移植治疗的临床资料,并阐述了术中注意事项,提出最佳手术时机及预后情况。结果:22例均采用自体大隐静脉移植,痊愈19例(86.4%)。截肢3例(13.6%),22例患者无死亡,随访2-9年,20例肢体功能恢复满意,2例移植段狭窄,但肢体功能良好。结论:自体大隐静脉移植是治疗周围血管损伤行之有效的方法之一。血管吻合的时间应在24h以内,最佳为8h以内。  相似文献   
65.
Female rats consistently show a pattern of differences in defensive behaviors compared to males which parallel the effects of exposure to a nonpainful threat stimulus (cat or cat odor) in the same tests and measures. These indications of greater defensiveness for females are particularly common in situations involving potential, as opposed to actual and present, threat, a factor which probably also reflects ceiling or floor effects in situations involving very intense defensiveness. In addition, pharmacological studies indicate sex differences in the effects of selective serotonin (5-HT) receptor agonists and antagonists on defensive responding. These findings indicate that sex effects must be considered in studies of the pharmacological control of defensive behaviors, and suggest that responsivity to sex effects may be an additional criterion for the suitability of animal models of anxiety.  相似文献   
66.
Is interleukin 2 a neuromodulator in the brain?   总被引:5,自引:0,他引:5  
A bidirectional flow of information exists between the CNS and the neuroendocrine and immune systems, representing an important homeostatic mechanism in the body. Lymphokines and other products of immunocompetent cells seem to play a crucial role in this communication and seem to exert powerful effects on neurones in the brain. In this article, Giuseppe Nisticò and Giovambattista De Sarro describe the central effects following interleukin 2 (IL-2) microinfusion into several areas of the rat brain. The locus coeruleus seems to be the main site in the brain through which IL-2 exerts soporific effects. In addition, the possible transducing mechanisms coupling IL-2 receptor stimulation and the electroencephalogram (EEG) spectrum power responses elicited from the locus coeruleus seem to involve stimulation of specific receptors coupled to adenylate cyclase through a Gi protein.  相似文献   
67.
68.
69.
Choriocarcinoma is one of the most serious forms of gestational trophoblastic tumor. It is a malignant tumor from the epithelium of the chorionic villi. The most frequent location site is the uterus. Associated with ectopic pregnancy, it is extremely rare and in general, very aggressive. In 75% of the cases, it items from distant metastasis; therefore, a histological examination of the tubes must be performed in all ectopic pregnancies. Our patient was a 33-year-old woman who was admitted to emergency room (ER) with an intense pain in the right, iliac cavity, and limited genital bleeding. During the exploration, there was abdominal pain, with doubtful signs of peritoneal irritation. The vaginal ultrasound offered an image that was compatible with an extra uterine pregnancy in the left appendages. At emergency, right salpingectomy was performed via laparotomy. The patient was treated with polychemotherapy and contraceptives for a year, with no recurrence of the disease. Control follow-up was performed using beta-human chorionic gonadotropin (HCG) testing on a weekly basis during the first month and then bi-monthly during the first year of follow-up.  相似文献   
70.
Effect of sorbinil on blood-retinal barrier in early diabetic retinopathy   总被引:1,自引:0,他引:1  
To study the effect of sorbinil on the alteration of the blood-retinal barrier, 32 adult-onset, non-insulin-dependent diabetic patients with minimal or no retinopathy were randomly assigned to receive either oral sorbinil (250 mg once a day) or a placebo for 6 mo. All patients underwent fundus photography, fluorescein angiography, and vitreous fluorophotometry before treatment and at 3 and 6 mo after treatment. Vitreous fluorophotometry data showed that the alteration of the blood-retinal barrier increased significantly less in the sorbinil-treated group compared with the placebo group during the 6-mo study period. Side effects were limited to hypersensitivity reactions, with skin rash and fever, in only 2 of the 16 patients who received the drug. These hypersensitivity reactions disappeared with discontinuation of the medication. Aldose-reductase inhibition may play an important role in stabilization of the blood-retinal barrier in early diabetic retinopathy.  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