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   153662篇
  免费   31064篇
  国内免费   2400篇
耳鼻咽喉   5208篇
儿科学   5662篇
妇产科学   2453篇
基础医学   3453篇
口腔科学   1564篇
临床医学   26791篇
内科学   47882篇
皮肤病学   7507篇
神经病学   14776篇
特种医学   6399篇
外科学   41325篇
综合类   416篇
现状与发展   72篇
一般理论   1篇
预防医学   7127篇
眼科学   3470篇
药学   1155篇
  1篇
中国医学   23篇
肿瘤学   11841篇
  2024年   689篇
  2023年   4802篇
  2022年   1241篇
  2021年   3192篇
  2020年   6072篇
  2019年   2240篇
  2018年   7476篇
  2017年   7393篇
  2016年   8476篇
  2015年   8482篇
  2014年   15579篇
  2013年   15735篇
  2012年   5656篇
  2011年   5651篇
  2010年   10450篇
  2009年   14291篇
  2008年   5894篇
  2007年   4149篇
  2006年   6549篇
  2005年   3812篇
  2004年   3078篇
  2003年   2045篇
  2002年   2115篇
  2001年   3858篇
  2000年   3079篇
  1999年   3268篇
  1998年   3660篇
  1997年   3470篇
  1996年   3363篇
  1995年   3210篇
  1994年   1952篇
  1993年   1571篇
  1992年   1424篇
  1991年   1464篇
  1990年   1099篇
  1989年   1232篇
  1988年   1045篇
  1987年   887篇
  1986年   913篇
  1985年   746篇
  1984年   559篇
  1983年   540篇
  1982年   532篇
  1981年   406篇
  1980年   370篇
  1979年   331篇
  1978年   337篇
  1977年   408篇
  1975年   288篇
  1972年   312篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
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   
82.
The diagnosis of acute disseminated encephalomyelitis (ADEM) is frequently missed or delayed with consequent delay in instituting therapy in the crucial phase of the illness. The role of MRI in the diagnosis of ADEM is well established, however, the value of its early utilization of treatment on the outcome of patients has not been adequately stressed. Three patients with ADEM are described. Delay in the diagnosis of the first was associated with severe sequelae, while in the other two early diagnosis and institution of corticosteroid therapy which was facilitated by MRI, was associated with a better outcome. MRI should be carried out early once the diagosis of ADEM is entertained.  相似文献   
83.
Background: Molecular theories of general anesthesia often are divided into two categories: (l) Anesthetics may bind specifically to proteins, such as ionic channels, and alter their function directly, and (2) anesthetics may alter the functions of integral membrane proteins indirectly through modification of the physical properties of the membrane. Recent studies have provided evidence that anesthetics can bind to proteins and modify their function directly, bringing into question the role of the membrane in anesthetic interactions. To reexamine the role of membrane lipids in anesthetic interactions, an experimental approach was used in which the membrane lipid composition could be systematically altered and the impact on anesthetic interactions with potential targets examined.

Methods: Sodium channels from human brain cortex were incorporated into planar lipid bilayers with increasing cholesterol content. The anesthetic suppression of these channels by pentobarbital was quantitatively examined by single channel measurements under voltage-clamp conditions.

Results: Changes in cholesterol content had no effect on measured channel properties in the absence of anesthetic. In the presence of pentobarbital, however, cholesterol inhibited anesthetic suppression of channel ionic currents, with 1.9% (weight/weight, corresponding to 3.5 mol%) cholesterol decreasing anesthetic suppression of sodium channels by half.  相似文献   

84.
85.
86.
Summary: This is the first report of the largest study of blood pressure measurement in pregnancy in a New Zealand population using standardized definitions and methodology. Over 3,800 women who delivered in an 8-month period in the Wellington region were included in the study. Blood pressure measurement and the presence of oedema and proteinuria were recorded from booking until delivery and in the puerperium. Only 2.7% of women were unable to be contacted after delivery for details on outcomes. The results established normal ranges for blood pressure throughout pregnancy. The data show that Mood pressure greater than 140/90 until 35 weeks' gestation is outside 2 standard deviations at all gestations and justifies using these measurements as the definition of hypertension in pregnancy. The fall in blood pressure in the 2nd trimester was less than 1 mm Ffg per week in both the systolic and diastolic pressures. This fall was smaller than previously recorded in other studies. Gestational hypertension was the commonest blood pressure abnormality occurring in 15.2% of the population. This represented 69% of the pregnant women with a hypertensive disorder. The overall incidence of both gestational hypertension and preeclampsia was 18.5% which is higher than reported in other parts of the world. In this study obesity was significantly associated with hypertensive disorders in pregnancy. An arm circumference of >33 cm, one of the measurements of obesity, was found in 6.8% of the study population. Even after the effect of arm circumference was taken into account, hypertensive disorders were also more common in Pacific Island women. Ankle oedema was significantly associated with the development of both gestational hypertension and preeclampsia but the incidence of oedema was noted in only 11.9% of the subjects.  相似文献   
87.
The efficacy and safety of ketoprofen and paracetamol were compared for the treatment of acute migraine in a randomized, double-blind study of 64 patients. Thirty-four patients received ketoprofen 100 mg intramuscularly, and 30 patients received paracetamol 500 mg intramuscularly. Partial or complete relief of pain and other symptoms was achieved 15 to 20 minutes after administration in the ketoprofen group and within 35 minutes in the paracetamol group. Complete relief of pain was achieved within 30 to 40 minutes after ketoprofen in 28 patients (82.5%) compared to 5 patients (17.5%) in the paracetamol group. Six of the patients treated with ketoprofen needed a second dose for complete relief of pain during the 4-hour follow-up period. Side effects were rare and minimal. Our findings suggest that ketoprofen produced statistically significant benefit in the treatment of acute migraine.  相似文献   
88.
89.
90.
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