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   148498篇
  免费   32466篇
  国内免费   2390篇
耳鼻咽喉   5168篇
儿科学   5358篇
妇产科学   2368篇
基础医学   2971篇
口腔科学   1481篇
临床医学   26615篇
内科学   46943篇
皮肤病学   7426篇
神经病学   14704篇
特种医学   6330篇
外科学   40774篇
综合类   243篇
现状与发展   72篇
预防医学   6977篇
眼科学   3320篇
药学   924篇
中国医学   20篇
肿瘤学   11660篇
  2024年   512篇
  2023年   4801篇
  2022年   1169篇
  2021年   3094篇
  2020年   6023篇
  2019年   2148篇
  2018年   7375篇
  2017年   7326篇
  2016年   8406篇
  2015年   8382篇
  2014年   15460篇
  2013年   15577篇
  2012年   5400篇
  2011年   5427篇
  2010年   10301篇
  2009年   14205篇
  2008年   5710篇
  2007年   3954篇
  2006年   6417篇
  2005年   3693篇
  2004年   2962篇
  2003年   1935篇
  2002年   2016篇
  2001年   3782篇
  2000年   2988篇
  1999年   3192篇
  1998年   3629篇
  1997年   3450篇
  1996年   3353篇
  1995年   3202篇
  1994年   1936篇
  1993年   1558篇
  1992年   1370篇
  1991年   1399篇
  1990年   1055篇
  1989年   1172篇
  1988年   1010篇
  1987年   848篇
  1986年   883篇
  1985年   712篇
  1984年   544篇
  1983年   517篇
  1982年   511篇
  1981年   393篇
  1980年   356篇
  1979年   309篇
  1978年   328篇
  1977年   397篇
  1975年   278篇
  1972年   279篇
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
151.
152.
INTRODUCTION: The clinical presentation of morphea varies from localized plaques to generalized eruptions. Its cause remains unknown and medical treatments have often proved unsatisfactory. Studies have previously shown that improvement of hypertrophic scars and fibrotic skin can be achieved with the use of a 585 nm pulsed dye laser (PDL). METHODS: A case of plaque-type morphea was treated with 585 nm pulsed dye laser irradiation at an average fluence of 5.0 J/cm2 at bimonthly time intervals. RESULTS: Marked clinical improvement as evidenced by improved pliability and skin coloration was seen after 4 successive PDL treatments. No side effects or complications were encountered. CONCLUSION: Pulsed dye laser therapy is a viable treatment option for morphea. The mechanism of its effect in this condition remains unknown.  相似文献   
153.
The prevalence of heavy alcohol consumption is a major problem of increasing proportions throughout the world. Although alcohol sensitizing drugs and more recently serotonin uptake inhibitors are drug interventions with some following, their long term beneficial consequences have yet to be demonstrated. In recent years, we have demonstrated that manipulating activity in the renin-angiotensin system will dramatically alter voluntary alcohol consumption in rats. Based on these findings, the present study evaluated the ability of a class of drugs known as the angiotensin converting enzyme inhibitors to reduce voluntary alcohol drinking in laboratory animals. These drugs prevent the conversion of angiotensin I to angiotensin II. They have been licensed for use in Europe and North America and are indicated in the treatment of hypertension. Our experiments showed that both captopril (Capoten, Squibb) and enalapril (Vasotec, Merck Sharpe & Dohme) can reduce alcohol drinking in both normotensive and hypertensive animals regardless of whether the pattern of intake is in a bout or of a less exaggerated nature. Furthermore, this change in alcohol intake can occur without concomitant changes in blood pressure, plasma renin activity, overall fluid balance, or the distribution and metabolism of alcohol. Taken together these findings suggest that the angiotensin converting enzyme inhibitors should be evaluated in a clinical setting for they may prove to be a useful new treatment or treatment adjunct for alcohol abuse in humans.  相似文献   
154.
155.
156.
Concanavalin A-induced lymphocyte proliferation was studied in 25 patients with alcoholic hepatitis or compensated alcoholic cirrhosis. Nine alcoholics without evidence of liver disease were also evaluated. A nonlinear correlation equation, which was natural logarithmic, was applied to individual dose-response proliferation curves and permitted comparisons between patient groups and controls. The proliferative response in all patient groups was significantly lower when compared to healthy controls and was independent of the presence or absence of liver disease. This suggests that some changes in immune function observed in alcoholics may be linked to the direct effects of alcohol on the immune system rather than to the associated liver disease.  相似文献   
157.
Objectives Compare the effect of high doses of inhaled corticosteroids on bone loss in subjects with moderate to severe asthma or mild asthma, and examine the influence of dietary intake on bone metabolism. Design A survey on the effects of corticotherapy and nutrition on bone density was conducted in 74 subjects currently being treated for asthma in the asthma clinic of Hospital Laval (Sainte-Foy, Quebec, Canada). Fifty-eight subjects completed the study (attrition RATE=15%).

Main outcome measures In all subjects expiratory volumes were determined and urinary analysis was conducted for hydroxyproline, calcium, phosphorus, and cortisol levels. Osteocalcin, calcium, phosphorus, cortisol, alkaline phosphatase, and γ-glutamyltransferase levels were measured in blood samples. Bone density of the lumbar spine was determined by means of dual-energy x-ray absorptiometry. Nutrition evaluation was based on a 3-day food diary analyzed using progiciel Nutri 91. The nutritional parameters examined were calcium; phosphorus; magnesium; zinc; vitamins A, C, and D; protein; total fiber; oxalates; energy; caffeine; and alcohol in relation to bone density.

Subjects Thirty-one patients with moderate to severe asthma who had been taking more than 1,000 μg beclomethasone per day or the equivalent for more than 2 years and 27 patients with mild asthma who were taking less than 500 μg beclomethasone per day or the equivalent.

Statistical analyses performed Four factor analysis of variance with hierarchized interactions of four levels, Duncan's test, Pearson correlation coefficients.

Results Blood levels of osteocalcin and protein intake were lower in patients with moderate to severe asthma than in those with mild asthma (P<.05). Significant correlations (P<.02) were observed between bone density and calcium intake (r=.40), phosphorus intake (r=.35), protein intake (r=.30), and serum alkaline phosphatase level (r=−.30). Bone density was not significantly different between the two groups of patients with asthma.

Applications A follow-up of patients with asthma who are taking inhaled corticosteroids is needed to assess bone density, osteocalcin levels, and dietary intakes of calcium. Verify if osteocalcin level decreases over time in patients with moderate to severe asthma, monitor possible modifications in bone density, and verify if the correlation between dietary calcium and bone density is maintained. J Am Diet Assoc. 1997;97:1401–1406.  相似文献   

158.
EDITORIAL COMMENT: We accepted this case for publication to remind readers that although uterine rupture during labour in a primigravida is extremely uncommon it does occur, or at any rate nulliparas can develop abdominal pain and shock in labour with a haemoperitoneum resulting from a tear in a vein in the lower posterior uterine wall. When one sees the hugely dilated uterine and ovarian venous plexuses at Caesarean section it is easy to believe that bleeding from such a vessel during labour could be prodigious. This case suggests that a dilated vein with blood flow derangements may be the cause. Nonetheless, as the authors warn us, the necessary response is not a precise diagnosis, but rapid laparotomy. See also Editorial Comment to Chin MMS, Harvey JA, Duffy BL. Uterine rupture during labour in a primigravida. Aust NZ J Obstet Gynaecol 1996; 36: 210.  相似文献   
159.
The incidence of wound botulism is increasing and the epidemiology of the disease is changing. The majority of new cases are associated with injection drug use, in particular, the use of Mexican black tar heroin. This case report and discussion of wound botulism illustrate the following important points: Dysphagia, dysphonia, diplopia, and descending paralysis, in association with injection drug use, should alert the treating physician to the possibility of wound botulism. In such patients, the onset of respiratory failure may be sudden and without clinically obvious signs of respiratory weakness. For the reported patient, maximum inspiratory force measurements were the only reliable indicator of respiratory muscle weakness. This is a measurement not routinely performed in the ED, but may prove essential for patients with suspected wound botulism. To minimize the effect of the botulinum toxin and to decrease length of hospital stay, antitoxin administration and surgical wound debridement should be performed early.  相似文献   
160.
A 33-year-old African woman was evaluated for tender nodules on her feet. Accompanied by her four children, she had recently immigrated from Somalia. Before her immigration, she resided in a Kenyan refugee camp for approximately 1 year, where she walked barefoot in sand and dirt. The patient stated that she and her four children, as well as many people living in the same compound, had similar, tender lesions on their feet. Her children were "treated" by their grandmother, who removed the contents of their lesions with a safety pin.
On physical examination the patient had numerous tender, isolated, and clustered hyperkeratotic, crusted papules, measuring 4–6 mm, on the plantar and periungual surfaces. Several lesions were ulcerated (Figs 1 and 2). The hyperkeratotic masses were debrided with a surgical blade. An intact, white, coiled structure was curetted from each papule, leaving numerous empty crater-like lesions (Fig. 3), which were identified on histologic sections as Tunga penetrans. Microscopic examination of unstained specimens showed branching, thin, translucent tubular structures with numerous eggs. Ring-shaped cross-sections of the organism's respiratory and digestive tracts were seen on hematoxylin and eosin stain (Fig. 4).
The patient received a 10-day course of dicloxacillin and topical bacitracin ointment. All lesions were healed within 1 week of therapy.  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