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   15547篇
  免费   1365篇
  国内免费   25篇
耳鼻咽喉   143篇
儿科学   501篇
妇产科学   395篇
基础医学   2053篇
口腔科学   375篇
临床医学   1685篇
内科学   2806篇
皮肤病学   281篇
神经病学   1390篇
特种医学   539篇
外科学   2558篇
综合类   301篇
一般理论   18篇
预防医学   1378篇
眼科学   386篇
药学   1238篇
  3篇
中国医学   8篇
肿瘤学   879篇
  2021年   219篇
  2020年   138篇
  2019年   228篇
  2018年   253篇
  2017年   181篇
  2016年   221篇
  2015年   262篇
  2014年   363篇
  2013年   517篇
  2012年   751篇
  2011年   827篇
  2010年   412篇
  2009年   387篇
  2008年   657篇
  2007年   671篇
  2006年   686篇
  2005年   587篇
  2004年   580篇
  2003年   581篇
  2002年   478篇
  2001年   459篇
  2000年   499篇
  1999年   409篇
  1998年   188篇
  1997年   123篇
  1996年   152篇
  1995年   142篇
  1994年   116篇
  1993年   134篇
  1992年   392篇
  1991年   351篇
  1990年   365篇
  1989年   340篇
  1988年   335篇
  1987年   313篇
  1986年   297篇
  1985年   329篇
  1984年   254篇
  1983年   210篇
  1982年   143篇
  1981年   121篇
  1980年   119篇
  1979年   235篇
  1978年   171篇
  1977年   122篇
  1976年   116篇
  1974年   119篇
  1973年   129篇
  1972年   112篇
  1970年   115篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Current immunosuppressive regimens for clinical transplantation are immunologically non-specific, are associated with acute and chronic toxic side-effects [1] and are unable to prevent chronic graft loss in a significant proportion of patients. Additionally, new and increasingly powerful drugs are being introduced to induce non-specific immunosuppression, and therefore this is likely to be followed by an increase in related complications such as the induction of cancers. Hence, there is a need for an alternative approach. It has been shown that long-term survival of murine cardiac grafts can be induced by the monoclonal antibody YIS 191 that depletes CD4 +T cells in vivo [2]. In this study, we have investigated the ability of a non-depleting antibody to produce better graft survival.  相似文献   
22.
OBJECTIVE: Radial arteries are increasingly used as conduits for coronary artery bypass grafts, but perioperative graft vasospasm remains a concern. In vitro testing has demonstrated the efficacy of phenoxybenzamine and verapamil/nitroglycerin as topical antispasmodic agents, but their duration of action in vivo is unknown. Using an in vivo mouse model, we measured their duration of action in functioning vascular grafts, and compared this to their in vitro duration of action in ungrafted vascular segments. METHODS: Two millimetre mouse aortic segments (C57/BL6) were incubated with phenoxybenzamine, verapamil/nitroglycerin, or buffer (controls) for 15 min in organ chambers. Isometric tension responses to phenylephrine and prostaglandin F2alpha were measured at 0, 2, 6 and 12 h post-incubation. In parallel, 36 murine infrarenal aortic interposition grafts (2 mm) were performed. Twelve grafts were pre-treated (15 min) with phenoxybenzamine, 12 with verapamil/nitroglycerin and 12 remained untreated (controls). Isometric tension responses to the same agonists were measured in grafts harvested 2, 6, 13 and 23 h after surgery. RESULTS: Phenoxybenzamine prevented alpha-adrenergic vasoconstriction for up to 16 h in vivo (grafts), and 12h in vitro (ungrafted segments). Verapamil/nitroglycerin was effective for at least 2 h in vitro, but did not prevent vasoconstriction after 2 h in vivo. CONCLUSIONS: The mouse model appears to be a useful technique for assessing the pharmacological properties of antispasmodic agents in vivo. Phenoxybenzamine has an extended action in arterial grafts in vivo. Verapamil/nitroglycerin is short-lived in vivo but lasts longer in vitro. Measurements of antispasmodic duration of action in vitro should be interpreted with caution.  相似文献   
23.
A methaemoglobin former, 4-aminopropiophenone (p-aminopropiophenone, PAPP), which is active only after metabolic activation in vivo, exhibits a sex difference in male Beagle dogs and bitches. Bitches produced more methaemoglobin for a given dose of PAPP than male dogs. The probable reason for this difference was a lower rate of N-hydroxylation in male dogs.  相似文献   
24.
Four women presented with symptomatic hypercalcaemia and raised concentrations of serum parathyroid hormone (PTH). In each case, serum calcium returned spontaneously to normal. In two patients serum PTH also fell to the normal range and biochemical relapse has not occurred despite prolonged follow-up. In the others, serum PTH remained elevated and subsequent symptomatic hypercalcaemia necessitated parathyroidectomy. In the first two cases, autoparathyroidectomy is the most likely explanation; the initial fall in serum calcium in the other two patients is unexplained. Large fluctuations in serum calcium may occur in some patients with hyperparathyroidism and prolonged and careful observation is required when this occurs.  相似文献   
25.
Walking after stroke. Measurement and recovery over the first 3 months   总被引:4,自引:0,他引:4  
Sixty surviving patients had their walking ability and speed assessed regularly over the first 3 months after an acute stroke. Sixty-four matched controls were studied to allow categorisation of speed as 'slow' or 'normal'. Fourteen patients never had any significant loss of walking speed; fifteen patients never recovered the ability to walk and one patient remained dependent upon verbal support. Of the 30 showing significant recovery, only 10 regained normal speed, and 8 remained dependent upon a physical aid at 3 months. Plotting individual recovery curves of walking speed over time showed the wide range of change which may be expected. It is argued that timing of gait over 10 metres is a valid reliable measure that is currently underused.  相似文献   
26.
27.
Chorioretinal neovascular membranes are a recognised but rare cause of late visual loss in eyes suffering contusional injuries. A series of eight cases is presented all with indirect choroidal ruptures involving the perifoveal region. Two main patterns of 'at risk' rupture were noted: a temporally situated rupture passing almost directly through the fovea, and a rupture which curves inferior or superior to the optic disc stopping just short of the fovea. In six of eight cases there was only a partial thickness rupture of the choroid. These neovascular membranes may present at any time after the original injury, either early (within six months of the injury), which could be related to persistence of the normal reparative neovascular response, or late (at least one year after the injury), which are more likely to have resulted from a secondary breakdown of the outer blood-retina barrier.  相似文献   
28.
A case of benign symmetrical lipomatosis (Madelung-Launois-Bensaude syndrome) is described. The characteristic clinical features and the association with chronic alcoholism are reported.  相似文献   
29.
We used bromodeoxyuridine to label the earliest generated cells of the murine cerebral cortex while they were dividing, and then observed their distributions at several instances later in development. Shortly before birth, many of the labelled cells were either above the cortical plate, in the marginal zone, or below it, in the region known as the subplate in other species. These cells had disappeared by postnatal day 21.  相似文献   
30.
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