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   30812篇
  免费   2425篇
  国内免费   319篇
耳鼻咽喉   372篇
儿科学   846篇
妇产科学   572篇
基础医学   3706篇
口腔科学   471篇
临床医学   3181篇
内科学   6170篇
皮肤病学   422篇
神经病学   2603篇
特种医学   1327篇
外科学   5146篇
综合类   1376篇
现状与发展   1篇
一般理论   51篇
预防医学   2303篇
眼科学   497篇
药学   1720篇
  5篇
中国医学   456篇
肿瘤学   2331篇
  2023年   317篇
  2022年   562篇
  2021年   1404篇
  2020年   766篇
  2019年   1037篇
  2018年   1278篇
  2017年   909篇
  2016年   869篇
  2015年   1127篇
  2014年   1525篇
  2013年   1841篇
  2012年   2705篇
  2011年   2620篇
  2010年   1575篇
  2009年   1288篇
  2008年   1803篇
  2007年   1899篇
  2006年   1639篇
  2005年   1486篇
  2004年   1222篇
  2003年   1014篇
  2002年   859篇
  2001年   267篇
  2000年   205篇
  1999年   210篇
  1998年   170篇
  1997年   141篇
  1996年   146篇
  1995年   119篇
  1994年   93篇
  1993年   91篇
  1992年   116篇
  1991年   119篇
  1990年   116篇
  1989年   124篇
  1988年   103篇
  1987年   100篇
  1986年   95篇
  1985年   100篇
  1984年   102篇
  1983年   87篇
  1982年   101篇
  1981年   82篇
  1980年   70篇
  1979年   82篇
  1978年   86篇
  1977年   46篇
  1975年   42篇
  1974年   44篇
  1973年   44篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
41.
96例神经症患者人格特质分析   总被引:3,自引:0,他引:3  
目的 对精神症患者与正常人的人格特质进行比较。方法 应用《修订卡氏16种人格因素量表》,对96例神经症患者与94名正常人进行测试。结果 神经症患者人格类型内向型占68.18%,焦虑型90.19%,明显高于正常组(P<0.001);因此C(稳定性)、E(恃强性)、F(兴奋性)、G(有恒性)、H(敢为性)的量表分低于正常人组(P<0.001);心理健康因素均分低于正常人组(P<0.001)。结论 神经症患者人格特质与正常人之间存在显著差异。  相似文献   
42.
The specialty of pain medicine, as noted by Lippe,“… justifies itself as a unique medical specialty by virtue of a distinct body of knowledge and a well-defined scope of practice. In common with other medical specialties, it is founded on an infrastructure of scientific research, education, and clinical practice [1].“ The traditional methods of education for healthcare providers, such as medical schools, nursing schools, physical therapy schools, and clinical psychology programs, do not prepare their students adequately for the delivery of evaluation and treatment services to patients experiencing pain. Also apparent, as evidenced by the dearth of medical literature, is that the traditional methods of educating pain specialists do not adequately prepare students for an effective approach to the realities of healthcare economics in their respective fields.The result of a lack of significant education in the economics of pain medicine can be financially devastating to a new practitioner who is practicing “good” medicine yet not meeting the financial obligations incipient in the operation of a multidisciplinary pain center or even a solo practice. One important concept in the study of healthcare economics is the issue of cost-effectiveness [2].  相似文献   
43.
44.
45.
Adrenarche, the prepubertal onset of adrenal production of dehydroepiandrosterone sulfate (DHEAS), is a distinctive aspect of the human life course. Yet its evolutionary origins remain unexplained. Production of DHEAS is associated with the development of the zona reticularis, a novel histological layer within the adrenal gland, derived from the fetal adrenal gland, and associated with primates more generally. Evidence that DHEAS is a neurosteroid, together with the fact that increases in DHEAS parallel patterns of cortical maturation from approximately age 6 years to the mid-20s, suggests that DHEAS may play an important role in extended brain maturation among humans. DHEAS has demonstrated effects on mood in humans, and acts at neuron receptor sites. I suggest three ways in which DHEAS may play a role in human brain maturation: 1) increasing activity of the amgydala; 2) increasing activity of the hippocampus; and 3) promoting synaptogenesis within the cortex. I propose that associated changes in fearfulness and anxiety, and memory, could act to increase social interaction with nonfamiliar individuals and shape cognitive development. Comparison with the African apes suggests that the timing of adrenarche in chimpanzees may be similar to that in humans, though the full course of age-related changes in DHEAS and their relationship to reproductive and brain maturation are not clear. The role of DHEAS as a physiological mechanism supporting increased brain development, extended life span, and decreased sexual dimorphism is most compatible with Kaplan et al.'s (2000) theory of the evolution of human life history and intergenerational transfers.  相似文献   
46.
47.
A randomized, placebo-controlled, double-blind study involving 60 subjects, aged 6-18 years old, was conducted over a period of 3 months to determine the effect of Pycnogenol® (a proprietary mixture of water-soluble bioflavonoids extracted from French maritime pine) on mild-to-moderate asthma. After baseline evaluation, subjects were randomized into two groups to receive either Pycnogenol® or placebo. Subjects were instructed to record their peak expiratory flow with an Assess® Peak Flow Meter each evening. At the same time, symptoms, daily use of rescue inhalers (albuterol), and any changes in oral medications were also recorded. Urine samples were obtained from the subjects at the end of the run-in period, and at 1-, 2-, and 3-month visits. Urinary leukotriene C4/D4/E4 was measured by an enzyme immunoassay. Compared with subjects taking placebo, the group who took Pycnogenol® had significantly more improvement in pulmonary functions and asthma symptoms. The Pycnogenol® group was able to reduce or discontinue their use of rescue inhalers more often than the placebo group. There was also a significant reduction of urinary leukotrienes in the Pycnogenol® group. The results of this study demonstrate the efficacy of Pycnogenol® as an adjunct in the management of mild-to-moderate childhood asthma.  相似文献   
48.
49.
Syncopes due to compulsive respiratory stereotypies were studied in eight patients with autistic features. Most had been referred for episodes thought to be intractable epileptic seizures. Polygraphic recording showed two types of syncope, one induced by prolonged apnea and the other by a prolonged Valsalva maneuver. Fenfluramine, 1.5–3 mg/kg per day, was given in an open trial. In four of five cases with frequent Valsalva maneuvers, respiratory stereotypies and syncopes were suppressed for 2–18 months. Patients with periodic apneas were more severely retarded and had less clear benefit. Side effects consisted of dose-dependent sedation and mild weight loss which stabilized without interrupting treatment. We suggest that these syncopes are volitional and may be associated with pleasant sensations. A double-blind placebo-controlled trial of fenfluramine seems warranted in such patients.  相似文献   
50.
Osteogenesis is synergistically enhanced by the combined effect of complimentary factors. This study showed that Nell-1 and BMP-2 synergistically enhanced osteogenic differentiation of myoblasts and phosphorylated the JNK MAPK pathway. The findings are important because of the osteochondral specificity of Nell-1 signaling and the potential therapeutic effects of coordinated BMP-2 and Nell-1 delivery. INTRODUCTION: BMPs play an important role in the migration and proliferation of mesenchymal cells and have a unique ability to alter the differentiation of mesenchymal cells toward chondrogenic and osteogenic lineages. Signaling upstream of Cbfa1/Runx2, BMPs effects are not limited to cells of the osteoblast lineage. Thus, additional osteoblast-specific factors that could synergize with BMP-2 would be advantageous for bone regeneration procedures. NELL-1 (NEL-like molecule-1; NEL [a protein strongly expressed in neural tissue encoding epidermal growth factor like domain]) is a novel growth factor believed to preferentially target cells committed to the osteochondral lineage. MATERIALS AND METHODS: C2C12 myoblasts were transduced with AdLacZ, AdNell-1, AdBMP-2, or AdNell-1+AdBMP-2 overexpression viruses. Effects were studied by cell morphology, alkaline phosphatase activity, osteopontin production, and MAPK signaling. Additionally, in a nude mouse model, viruses were injected into leg muscles, and new bone formation was examined after 2 and 8 wk. RESULTS: C2C12 myoblasts co-transduced with AdNell-1+AdBMP-2 showed a synergistic effect on osteogenic differentiation as detected by alkaline phosphatase activity and osteopontin production. Nell-1 stimulation on AdNell-1 + AdBMP-2 preconditioned C2C12 cells revealed significant activation of the non-BMP-2 associated c-Jun N-terminal kinase (JNK) MAPK signaling pathway, but not the p38 or extracellular signal-regulated kinase (ERK1/2) MAPK pathways. Importantly Nell-1 alone did not induce osteogenic differentiation of myoblasts. In a nude mouse model, injection of AdNell-1 alone stimulated no bone formation within muscle; however, injection of AdNell-1+AdBMP-2 stimulated a synergistic increase in bone formation compared with AdBMP-2 alone. CONCLUSIONS: These findings are important because of the confirmed osteochondral specificity of Nell-1 signaling and the potential therapeutic effects of enhanced BMP-2 action with coordinated Nell-1 delivery.  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