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   19912篇
  免费   1179篇
  国内免费   138篇
耳鼻咽喉   171篇
儿科学   466篇
妇产科学   377篇
基础医学   2274篇
口腔科学   749篇
临床医学   1888篇
内科学   4259篇
皮肤病学   412篇
神经病学   1245篇
特种医学   453篇
外国民族医学   5篇
外科学   2751篇
综合类   515篇
一般理论   22篇
预防医学   1637篇
眼科学   746篇
药学   1899篇
中国医学   227篇
肿瘤学   1133篇
  2024年   32篇
  2023年   254篇
  2022年   724篇
  2021年   1119篇
  2020年   744篇
  2019年   911篇
  2018年   1064篇
  2017年   737篇
  2016年   802篇
  2015年   819篇
  2014年   1105篇
  2013年   1275篇
  2012年   1750篇
  2011年   1795篇
  2010年   1063篇
  2009年   815篇
  2008年   1182篇
  2007年   1059篇
  2006年   891篇
  2005年   766篇
  2004年   599篇
  2003年   489篇
  2002年   417篇
  2001年   73篇
  2000年   96篇
  1999年   64篇
  1998年   56篇
  1997年   46篇
  1996年   46篇
  1995年   40篇
  1994年   24篇
  1993年   36篇
  1992年   28篇
  1991年   22篇
  1990年   22篇
  1989年   23篇
  1988年   18篇
  1987年   15篇
  1986年   18篇
  1985年   14篇
  1984年   23篇
  1983年   22篇
  1982年   17篇
  1981年   13篇
  1980年   12篇
  1979年   16篇
  1978年   13篇
  1976年   11篇
  1974年   8篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Malignant melanoma is notorious for distant metastases. Median survival for stage IV melanoma is 6-10 months and 5 year survival is less than 5%. Median survival for melanoma with brain metastases is even lower i.e. 2 to 9 months. Here a case is reported who was treated for melanoma of sole of left foot with ipsilateral inguinal adenopathy and brain metastases in 2001 and is still surviving disease-free after a lapse of 8 years.  相似文献   
103.
The objective of this study was to examine the public health relevance of the prevalence of dental fear in Kuwait and the resultant barrier that it creates regarding access to dental care. The study analysis demonstrated a high prevalence of dental fear and anxiety in the Kuwaiti population and a perceived need for anesthesia services by dental care providers. The telephone survey of the general population showed nearly 35% of respondents reported being somewhat nervous, very nervous, or terrified about going to the dentist. In addition, about 36% of the population postponed their dental treatment because of fear. Respondents showed a preference to receive sedation and anesthesia services as a means of anxiety relief, and they were willing to go to the dentist more often when such services were available. People with high fear and anxiety preferred to receive some type of medication to relieve their anxiety. In conclusion, the significance and importance of the need for anesthesia services to enhance the public health of dental patients in Kuwait has been demonstrated, and improvements are needed in anesthesia and sedation training of Kuwaiti dental care providers.  相似文献   
104.
The aim of this study was to observe the histological features of chronic gastritis and associated effects due to Helicobacter pylori infection in 176 randomly selected antral biopsy specimens of chronic gastritis cases. The specimens were reviewed for the presence or absence of H.pylori. The activity (neutrophilic infiltration) of gastritis and the presence or absence of mucosa-associated lymphoid tissue (MALT) were also noted. Chi-square test (Pearson value) was used to analyze categorical variables. H.pylori was detected in 110 (62.5%) cases of chronic gastritis. There was a significant association between H.pylori infection and activity of chronic gastritis (p=0.002). Lymphoid aggregates were significantly more frequently noted in H.pylori-positive patients (68.2%) vs. H.pylori negative group (47%), (p=0.005). It is concluded that H.pylori is significantly associated with active chronic gastritis and with formation of mucosa-associated lymphoid tissue (MALT), which may develop into gastric lymphoma (MALT type).  相似文献   
105.
Ruptured abdominal aorta aneurysm (rAAA) is the 13th leading cause of death in the United States. Despite many advances in the field of vascular surgery, the improvement in mortality rates of rAAA have been very modest. Although endovascular repair has surpassed open repair for elective AAA repair in the United States, open rAAA repair remains the most common therapy for this devastating vascular emergency. In this article, we discuss open surgical management for rAAA. We also describe a fast-track algorithm we have developed at the University of Massachusetts where open and endovascular repairs play equally important roles in management of rAAA.  相似文献   
106.
Melatonin, the major hormone produced by the pineal gland, is shown to have anticonvulsant effects. Nitric oxide (NO) is a known mediator in seizure susceptibility modulation. In the present study, the involvement of NO pathway in the anticonvulsant effect of melatonin in pentylenetetrazole (PTZ)-induced clonic seizures was investigated in mice. Acute intraperitoneal administration of melatonin (40 and 80 mg/kg) significantly increased the clonic seizure threshold induced by intravenous administration of PTZ. This effect was observed as soon as 1 min after injection and lasted for 30 min with a peak effect at 3 min after melatonin administration. Combination of per se non-effective doses of melatonin (10 and 20 mg/kg) and nitric oxide synthase (NOS) substrate L-arginine (30, 60 mg/kg) showed a significant anticonvulsant activity. This effect was reversed by NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg), implying an NO-dependent mechanism for melatonin effect. Pretreatment with L-NAME (30 mg/kg) and N(G)-nitro-L-arginine (L-NNA, 10 mg/kg) inhibited the anticonvulsant property of melatonin (40 and 80 mg/kg) and melatonin 40 mg/kg, respectively. Specific inducible NOS (iNOS) inhibitor aminoguanidine (100 and 300 mg/kg) did not affect the anticonvulsant effect of melatonin, excluding the role of iNOS in this phenomenon, while pretreatment of with 7-NI (50 mg/kg), a preferential neuronal NOS inhibitor, reversed this effect. The present data show an anticonvulsant effect for melatonin in i.v. PTZ seizure paradigm, which may be mediated via NO/L-arginine pathway by constitutively expressed NOS.  相似文献   
107.
PURPOSE: To compare the efficacy and safety of dapoxetine, paroxetine, and placebo for the oral pharmacotherapy of premature ejaculation. MATERIALS AND METHODS: Three hundred forty potent men with premature ejaculation were recruited to this study. Patients were randomly assigned to receive 60 mg dapoxetine (group 1, n = 115), or 20 mg paroxetine (group 2, n = 113) or placebo (group 3, n = 112) orally daily during a 12-week period for each agent. The efficacy of the 3 treatments was assessed every 2 weeks during treatment and at the end of study using responses to International Index of Erectile Function (IIEF), intravaginal ejaculatory latency time (IELT) evaluation, mean intercourse satisfaction domain, mean weekly coitus episodes and adverse drug effects. RESULTS: At the end of the 12-week treatment with dapoxetine, paroxetine, and placebo, the mean IELT was increased from 38, 31 and 34 seconds to 179, 370 and 55 seconds, respectively (P = 0.01 in group 1 and P = 0.001 in group 2). Baseline mean intercourse satisfaction domain values of International Index of Erectile Function of 10, 11, and 11 reached 14, 17 and 12 at the end of the 12-week treatment in groups 1, 2, and 3 respectively (P = 0.03 in groups 1, 2). The mean weekly intercourse episodes increased from pretreatment values of 1.4, 1.3, and 1.3 to 2.2, 2.5 and 1.4, for dapoxetine, paroxetine and placebo, respectively (P = 0.04 in groups 1, 2). The incidence of adverse effects with dapoxetine and paroxetine was significantly higher (P = 0.04 in groups 1, 2) compared to that of placebo. CONCLUSIONS: Paroxetine appears to provide significantly better results in terms of IELT and intercourse satisfaction versus dapoxetine. Each treatment was well tolerated.  相似文献   
108.
It is previously reported that the HPA axis plays role in the inhibitory effect of pain on tolerance development to analgesic effect of opioids. The present study was designed to investigate whether the chronic co-administration of dexamethasone as a glucocorticoid is also able to prevent or reverse analgesic tolerance to morphine and to compare the expression of G(alphai/o) and G(beta) subunits of G proteins in the context of chronic dexamethasone, development of morphine tolerance and their combination. Analgesic tolerance to morphine was induced by chronic intraperitoneally (i.p.) administration of morphine 20 mg/kg to male Wistar rats weighing 200-240 g within 4 consecutive days and analgesia was assessed using tail-flick test. Chronic dexamethasone was applied using 4 daily i.p. injections. Lumbar spinal tissues were assayed for the expression of G(alphai/o) and G(beta) proteins using "semiquantitative PCR" normalized to beta-actin gene expression. Results showed that chronic administration of dexamethasone could reduce and reverse the development of tolerance in rats that received chronic i.p. injections of morphine. Chronic administration of dexamethasone significantly increased the expression of G(alphai/o), while chronic administration of morphine did not change its expression. The expression of G(beta), however, was increased after the chronic administration of morphine, but did not change after the administration of chronic dexamethasone. None of these increases were observed when morphine and dexamethasone were co-administered. We conclude that the development of tolerance to analgesic effect of morphine could be prevented and reversed by dexamethasone co-administration. The increase in G(alphai/o) genes expression produced by chronic dexamethasone may facilitate the opioid signaling pathway and compensate for morphine-induced tolerance.  相似文献   
109.
Despite the fact that common surgical techniques for the treatment of genu varum usually correct the malalignment in the affected knee, these methods have significant complications and cause problems in the long term. Retro-tubercle opening-wedge high tibial osteotomy is among the newer techniques for the treatment of genu varum. The goal of this study was to compare the results of retro-tubercle opening-wedge high tibial osteotomy with those of medial opening-wedge osteotomy. In a randomized, controlled trial, 72 patients with varus knees who were scheduled for surgery were assigned into either the retro-tubercle opening-wedge high tibial osteotomy (n=34) or medial opening-wedge osteotomy groups (n=38). Groups were matched for age and sex. The position of the patella was compared with respect to the tuberosity and the upper tibial slope pre- and postoperatively. Patients were followed for an average of 13 months (range, 10-21 months). In the retro-tubercle opening-wedge high tibial osteotomy group, the length of the patellar tendon did not significantly differ pre- and postoperatively (P≥.5); however, in the medial opening-wedge osteotomy group, a statistically significant shortening was noted in patellar tendon postoperatively (P≤.05). Similarly, the tibial plateau inclination showed a statistically significant difference postoperatively in the medial opening-wedge osteotomy group, while the difference in the retro-tubercle opening-wedge high tibial osteotomy group did not reach statistical significance.  相似文献   
110.

Background  

While some studies have shown that long-limb gastric bypass with Roux limb length of 150 to 200 cm can attain better weight loss outcomes in super-obese patients (BMI >50 kg/m2) than the standard limb gastric bypass with Roux limb length of 100 to 150 cm, other studies have not shown similar findings. Additionally, no study has demonstrated the optimal length of the Roux limb that will result in ideal weight loss. The purpose of this study is to compare the long-term weight loss and weight regain of standard limb length (SLL) and long limb length (LLL) gastric bypass in patients with BMI >50 kg/m2.  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