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   26910篇
  免费   1227篇
  国内免费   68篇
耳鼻咽喉   363篇
儿科学   841篇
妇产科学   657篇
基础医学   3493篇
口腔科学   793篇
临床医学   2116篇
内科学   4835篇
皮肤病学   518篇
神经病学   2433篇
特种医学   939篇
外国民族医学   1篇
外科学   4032篇
综合类   89篇
一般理论   8篇
预防医学   2912篇
眼科学   582篇
药学   1911篇
中国医学   90篇
肿瘤学   1592篇
  2023年   173篇
  2022年   214篇
  2021年   448篇
  2020年   304篇
  2019年   391篇
  2018年   628篇
  2017年   511篇
  2016年   608篇
  2015年   665篇
  2014年   738篇
  2013年   1054篇
  2012年   1481篇
  2011年   1655篇
  2010年   853篇
  2009年   688篇
  2008年   1180篇
  2007年   1377篇
  2006年   1209篇
  2005年   1299篇
  2004年   1268篇
  2003年   1209篇
  2002年   1107篇
  2001年   658篇
  2000年   679篇
  1999年   578篇
  1998年   190篇
  1997年   168篇
  1996年   141篇
  1992年   353篇
  1991年   324篇
  1990年   348篇
  1989年   326篇
  1988年   307篇
  1987年   296篇
  1986年   317篇
  1985年   317篇
  1984年   245篇
  1983年   211篇
  1979年   247篇
  1978年   164篇
  1975年   157篇
  1974年   198篇
  1973年   199篇
  1972年   212篇
  1971年   175篇
  1970年   151篇
  1969年   194篇
  1968年   169篇
  1967年   159篇
  1966年   144篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Cytogenetic abnormalities are rarely found in patients with juvenile chronic myelogenous leukemia (JCML). In patients with chromosomal abnormalities, chromosomes 7 and 8 are usually involved. A case of JCML with 47 XXX and a 46 XX karyotype is described and the literature is reviewed. To our knowledge, this is the first case ever to have been reported.  相似文献   
62.
Activation of mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels protects the brain against ischemic or chemical challenge. Unfortunately, the prototype mitoK(ATP) channel opener, diazoxide, has mitoK(ATP) channel-independent actions. We examined the effects of BMS-191095, a novel selective mitoK(ATP) channel opener, on transient ischemia induced by middle cerebral artery occlusion (MCAO) in rats. Male Wister rats were subjected to 90 mins of MCAO. BMS-191095 (25 microg; estimated brain concentration of 40 micromol/L) or vehicle was infused intraventricularly before the onset of ischemia. In addition, the effects of BMS-191095 on plasma and mitochondrial membrane potentials and reactive oxygen species (ROS) production in cultured neurons were examined. Finally, we determined the effects of BMS-191095 on cerebral blood flow (CBF) and potassium currents in cerebrovascular myocytes. Treatment with BMS-191095 24 h before the onset of ischemia reduced total infarct volume by 32% and cortical infarct volume by 38%. However, BMS-191095 administered 30 or 60 mins before MCAO had no effect. The protective effects of BMS-191095 were prevented by co-treatment with 5-hydroxydecanoate (5-HD), a mitoK(ATP) channel antagonist. In cultured neurons, BMS-191095 (40 micromol/L) depolarized the mitochondria without affecting ROS levels, and this effect was inhibited by 5-HD. BMS-191095, similar to the vehicle, caused an unexplained but modest reduction in the CBF. Importantly, BMS-191095 did not affect either the potassium currents in cerebrovascular myocytes or the plasma membrane potential of neurons. Thus, BMS-191095 afforded protection against cerebral ischemia by delayed preconditioning via selective opening of mitoK(ATP) channels and without ROS generation.  相似文献   
63.
64.
Lactulose (10-20 g day(-1)) is used to treat constipation. At this therapeutic dose, its effects on colonic motility remain unknown. Twenty-two healthy subjects swallowed a probe with an infusion catheter, six perfused catheters and a balloon connected to a barostat. Colonic phasic and tonic motor activity was recorded in fasting state. In group 1, four volunteers ingested 15 g lactulose and motility was recorded for 5 h after entry of lactulose into the caecum; in group 2, motility was recorded during (3 h) and 2 h after intracolonic infusion of isoosmotic and isovolumetric solutions containing sodium chloride alone (n = 9) or with 15 g lactulose (n = 9). In a last group of volunteers, isotopic colonic transit after ingestion of lactulose (10 g,n = 9) was assessed and compared with a control group (n = 17). Ingestion or intracolonic infusion of 15 g lactulose significantly decreased barostat bag volume (maximal decrease: 45 +/- 12% and 35 +/- 9% of basal value respectively). Phasic contractions remained unchanged. Tonic and phasic motility was unchanged by the isotonic and isovolumetric infusion of saline. Ingestion of lactulose significantly accelerated isotopic colonic transit time compared with the control group. We conclude that in healthy humans, 10-15 g ingestion or intracaecal infusion of lactulose produces a prolonged tonic contraction that may be involved in the laxative effect of lactulose.  相似文献   
65.
A randomized, placebo-controlled clinical pilot study was performed in order to examine the effect of magnesium-orotate in male idiopathic infertility. Ten males were treated daily for 90 consecutive days with 3000 mg magnesium-orotate (Magnerot) tablets (Group M). As a control, ten other males were treated in the same way with placebo (Group P). Conventional microscopic sperm characteristics (sperm concentration, motility ratio, total number of motile sperm cells, normal morphology ratio), plus total and ionized magnesium levels in seminal plasma and blood serum were evaluated both prior to treatment and on day 90, at the conclusion of the study. No significant changes in sperm characteristics, blood ionized or total Mg, or ejaculate total Mg levels were detected. However, ejaculate ionized Mg levels increased in Group M from 0.18 +/- 0.05 to 0.30 +/- 0.05 (mmol/l; mean +/- SD, p < 0.05). Within the observation period of 3 months, one pregnancy occurred in the partner of a male from Group M. In conclusion, magnesium-orotate treatment at a dose of 3000 mg/day leads neither to a significant improvement of sperm variables nor does it increase the pregnancy rates of female partners of treated males as compared to those of controls. Thus, magnesium-orotate treatment was not shown to be effective therapy for idiopathic male infertility.  相似文献   
66.
6-keto-prostaglandin F1a and thromboxane B2 were determined in order to obtain more information about the prostacyclin synthesis and thromboxane A2 release in 3- to 18-year-old healthy children and in offspring of parents who have had an acute myocardial infarction before the age of 45. The authors demonstrated a reduction of plasma prostacyclin synthesis in children with a positive family history of premature coronary arterial disease. Thromboxane levels in the affected adolescent boys were significantly lower compared with the controls. The ratio of thromboxane:prostacyclin in endangered children did not show a significant difference from that of healthy controls. These data indicate that prostaglandins are a definitive marker for identifying cardiovascular risk children. It must be supposed that in adolescence, only in boys, with a positive family history of premature coronary arterial disease, a compensatory mechanism exists to protect them from developing an imbalance in the regulation of prostaglandins.  相似文献   
67.
Cavernous haemangiomas of the liver were surgically treated in 36 women and 14 men over a 10-year period. The tumours were solitary in 42 cases and multiple in 8. Locations were the right lobe in 39 cases, the left one in 5 and both lobes in 6. The size of the tumours ranged from 0.4 to 14 cm in diameter. Enucleation of tumours was carried out in 29 cases, an atypical liver resection in 19 cases, anatomical lobectomy in 2 cases and a right trisegmentectomy in 1 case. There was no mortality. Morbidity rate seems to be lower in patients who underwent enucleation. The authors indicate the importance of enucleation for removal of liver haemangiomas of various sizes.r>
Chirurgische Behandlung kavernöser Hämangiome der Leber
Zusammenfassung Über einen Zeitraum von 10 Jahren wurden kavernöse Hämangiome der Leber bei 36 Frauen und 14 Männern chirurgisch behandelt. Bei 42 Patienten waren die Tumoren solitär, bei 8 multipel. Sie waren in 39 Fällen im rechten, bei 5 Patienten im linken und bei 6 in beiden Leberlappen lokalisiert, ihr Durchmesser betrug 0,4 bis 14 cm. In 29 Fällen wurde eine Enukleation, in 19 eine atypische Leberresektion, in 2 eine anatomische Lobektomie und in einem Falle eine rechtsseitige Trisegmentektomie durchgeführt. Die Mortalität war gleich Null; die Morbiditätsrate scheint bei den Patienten geringer, die mit Enukleation behandelt wurden. Der Beitrag hebt die Bedeutung der Enukleation zur Beseitigung von Leberhämangiomen unterschiedlicher Größe hervor.
  相似文献   
68.
69.
Between January 1987 and December 1988 thoracoscopic pleurodesis has been used as a standard treatment for idiopathic spontaneous pneumothorax. Bullae were electrocoagulated, and visceral and parietal pleurae were cauterized. Chemical pleurodesis with 50% glucose-solution was added. 34 procedures were performed on 32 patients. The average hospital stay was 8 +/- 2 days. One patient suffered from postoperative Horner-syndrome. No other complications occurred. Patients were re-evaluated 11 +/- 8 months after the operation. Recurrence was found in four patients within 30 days. These patients underwent pleurectomy. Another patient had recurrence after two months. He was again and successfully treated by thoracoscopic pleurodesis. Our data show improvement of the results as compared with simple chemical pleurodesis.  相似文献   
70.
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