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   7359篇
  免费   475篇
  国内免费   18篇
耳鼻咽喉   159篇
儿科学   280篇
妇产科学   192篇
基础医学   989篇
口腔科学   373篇
临床医学   488篇
内科学   1696篇
皮肤病学   175篇
神经病学   539篇
特种医学   255篇
外科学   1044篇
综合类   48篇
预防医学   718篇
眼科学   93篇
药学   436篇
中国医学   43篇
肿瘤学   324篇
  2023年   63篇
  2022年   109篇
  2021年   239篇
  2020年   121篇
  2019年   207篇
  2018年   273篇
  2017年   186篇
  2016年   177篇
  2015年   196篇
  2014年   262篇
  2013年   327篇
  2012年   450篇
  2011年   498篇
  2010年   334篇
  2009年   252篇
  2008年   395篇
  2007年   382篇
  2006年   353篇
  2005年   362篇
  2004年   337篇
  2003年   287篇
  2002年   253篇
  2001年   188篇
  2000年   221篇
  1999年   187篇
  1998年   80篇
  1997年   45篇
  1996年   42篇
  1995年   49篇
  1994年   51篇
  1993年   46篇
  1992年   91篇
  1991年   63篇
  1990年   72篇
  1989年   74篇
  1988年   67篇
  1987年   58篇
  1986年   45篇
  1985年   45篇
  1984年   35篇
  1983年   26篇
  1979年   23篇
  1978年   18篇
  1976年   22篇
  1975年   22篇
  1974年   23篇
  1973年   23篇
  1971年   21篇
  1970年   19篇
  1969年   16篇
排序方式: 共有7852条查询结果,搜索用时 15 毫秒
1.
2.
Summary In this work, we have studied the time-course of the effects of pharmacological administration of ovarian steroids on tyrosine hydroxylase (TH) activity in the limbic forebrain of ovariectomized rats. Administration of estradiol produced a late decrease in TH activity. This effect was found 24 hours after the last steroid injection, disappearing at 32 hours. It was antagonized by progesterone, since a single injection of this steroid to estradiol-pretreated rats reversed to control values the estradiol-induced decrease. Nevertheless, the administration of progesterone after estradiol treatment caused a short-time decrease in the limbic activity of TH, which was observed 4 hours after the last steroid injection, disappearing subsequently. On the other hand, the administration of progesterone alone produced a biphasic effect, with a reduction at 24 hours, followed by an increase at 32 hours. These effects were only observed in the animals non-treated with estradiol, disappearing with a previous treatment with estrogens. Hence, it can be concluded that both ovarian steroids may affect the limbic TH activity. Thus, estradiol produced a late inhibitory effect on the activity of this enzyme, which was antagonized by progesterone. Administration of the last one to estradiol-treated rats produced a short-time inhibitory effect, whereas its administration to non-treated rats produced a late biphasic effect (inhibition followed by stimulation), which was not observed in estradiol-treated rats.  相似文献   
3.
4.
The health care supervisor responsible for establishing a therapeutic milieu within a traditional hospital organization will have greater success if these suggested management strategies are employed. Decentralizing, improving organizational communication, and clarifying interdisciplinary role relationships are the strategies that support the integration of differing organizational approaches to management.  相似文献   
5.
6.
7.
Hydrocephalus and cavernoma of the cauda equina   总被引:1,自引:0,他引:1  
F Ramos  B de Toffol  B Aesch  M Jan 《Neurosurgery》1990,27(1):139-142
The association of a tumor of the cauda equina and hydrocephalus is unusual. We report a case of hydrocephalus with normal pressure associated with an equally rare affliction, a cavernous angioma of the cauda equina, which regressed after surgical ablation. The physiological mechanism involved is discussed.  相似文献   
8.
Summary BACKGROUND: Endometriosis is a relatively common pathology in women of childbearing age and of low parity but rarely shows extraperitoneal involvement. The main aim of this paper is to raise the attention of specialists to the necessity of carrying out penetrating diagnosis of nonspecific extraperitoneal masses occurring in women of reproductive age. METHODS: We performed a retrospective review of six patients diagnosed with extraperitoneal endometriosis who were treated at the Vega Baja University Hospital (Spain) during the last 5 years. RESULTS: Surgical treatment had positive results in five patients. The preoperative diagnosis was correctly made in only two patients. The accurate aetiology of endometriosis remains unknown and diagnosis is based on clinical and cytopathological findings. CONCLUSIONS: Surgical treatment of extraperitoneal endometriosis is recommended. However, postoperative follow-up is obligatory and hormonal suppressive therapy may be necessary. Medical treatment with gestagens, Danazol, or agonists of the gonadotropin-releasing hormone are ineffective in endometriomas which are bigger than 2 cm.   相似文献   
9.
BACKGROUND: Portugal has one of the highest mortality rates from stroke, a high prevalence of hypertension and probably a high salt intake level. AIM: To evaluate Portuguese salt intake levels and their relationship to blood pressure and arterial stiffness in a sample of four different adult populations living in northern Portugal. METHODS: A cross-sectional study evaluating 24-hour urinary excretion of sodium (24 h UNa+), potassium and creatinine, blood pressure (BP), and pulse wave velocity (PWV) as an index of aortic stiffness in adult populations of sustained hypertensives (HT), relatives of patients with previous stroke (Fam), university students (US) and factory workers (FW), in the context of their usual dietary habits. RESULTS: We evaluated a total of 426 subjects, mean age 50 +/- 22 years, 56% female, BMI 27.9+/-5.1, BP 159/92 mmHg, PWV 10.4+/-2.2 m/s, who showed mean 24h UNa+ of 202 +/- 64 mmol/d, corresponding to a daily salt intake of 12.3 g (ranging from 5.2 to 24.8). The four groups were: HT: n = 245, 49 +/- 18 years, 92% of those selected, 69% treated, BP 163/94 mmHg, PWV 11.9 m/s, 24 h UNa+ 212 mmol/d, i.e. 12.4 g/d of salt); Fam: n = 38, 64 +/- 20 years, 57 % of those selected, BP 144/88 mmHg, PWV 10.5 m/s, 24 h UNa+ 194 mmol/d, i.e. 11.1 g/d of salt; US: n = 82, 22 +/- 3 years, 57% of those selected, BP 124/77 mmHg, PWV 8.7 m/s, 24h UNa+ 199 mmol/d, i.e. 11.3 g/d of salt; FW: n = 61, 39 9 years, 47% of those selected, BP 129/79 mmHg, PWV 9.5 m/s, 24 h UNa+ 221 mmol/d, i.e. 12.9 g/d of salt. The ratio of urinary sodium/potassium excretion (1.9 (0.4) was significantly higher in HT than the other three groups. In the 426 subjects, 24h UNa+ correlated significantly (p < 0.01) with systolic BP (r = 0.209) and with PWV (r=0.256) after adjustment for age and BP. Multivariate analysis showed that BP, age and 24h UNa+ correlated independently with PWV taken as a dependent variable. CONCLUSIONS: Four different Portuguese populations showed similarly high mean daily salt intake levels, almost double those recommended by the WHO. Overall, high urinary sodium excretion correlated consistently with high BP levels and appeared to be an independent determining factor of arterial stiffness. These findings suggest that Portugal in general has a high salt intake diet, and urgent measures are required to restrict salt consumption in order to prevent and treat hypertensive disease and to reduce overall cardiovascular risk and events.  相似文献   
10.
The authors present the clinical case of a 31 year female with systemic vascular hypertension secondary to a 65 percent unilateral fibromuscular renal artery stenosis. The centellographic study demonstrated hypoperfusion on the right kidney and serious functional damage; the patient was subject to intraluminal renal angioplasty resulting in right renal arterial thrombosis, which was treated successfully with intra-arterial and intravenous streptokinase infusion. Following the thrombotic therapy, recanalization of the thrombosed artery and normal renal excretion of the contrast substance was observed.  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