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   18878篇
  免费   1575篇
  国内免费   205篇
耳鼻咽喉   87篇
儿科学   36篇
妇产科学   80篇
基础医学   759篇
口腔科学   221篇
临床医学   3417篇
内科学   3037篇
皮肤病学   77篇
神经病学   885篇
特种医学   301篇
外科学   1525篇
综合类   3389篇
一般理论   2篇
预防医学   3529篇
眼科学   68篇
药学   1921篇
  27篇
中国医学   490篇
肿瘤学   807篇
  2024年   70篇
  2023年   374篇
  2022年   596篇
  2021年   880篇
  2020年   808篇
  2019年   791篇
  2018年   866篇
  2017年   822篇
  2016年   888篇
  2015年   838篇
  2014年   1862篇
  2013年   1786篇
  2012年   1514篇
  2011年   1470篇
  2010年   1101篇
  2009年   897篇
  2008年   867篇
  2007年   746篇
  2006年   617篇
  2005年   556篇
  2004年   414篇
  2003年   333篇
  2002年   303篇
  2001年   247篇
  2000年   200篇
  1999年   154篇
  1998年   113篇
  1997年   95篇
  1996年   73篇
  1995年   58篇
  1994年   62篇
  1993年   60篇
  1992年   34篇
  1991年   39篇
  1990年   35篇
  1989年   16篇
  1988年   15篇
  1987年   18篇
  1986年   10篇
  1985年   12篇
  1984年   5篇
  1983年   2篇
  1982年   5篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
In the evolution of humans, many kinds of mutations in the human genome have been accumulated, providing credible genetic evidence for the study of human origins and migrations. The "out-of-Africa" hypothesis of modern human evolution and the genetic origin of the Japanese has come about by studying mitochondrial DNA.l,2 Recently, researchers have recognized the power of Y-chromosome markers in resolving migratory patterns of modern humans as more and more Y-chromosome single nucleotide polymorphism markers have been found. The markers on the nonrecombinant part of the Y-chromosome allows for the reconstruction of intact haplotypes which are probably the best genetic tools to study human migrations. We can analyze the paternal history of some people in different areas by Y-chromosome haplotypes.  相似文献   
92.
The aims were to investigate: (1) experiences of physical pain in elderly patients with hip fracture; (2) if background variables, confusion, experiences of pain and distress and interventions aimed at reducing pain and distress, functional ability, pain in the ambulance, and type of fracture varied between patients with more intense physical pain and patients with less intense physical pain. The sample included 49 patients, 70 years or older, with hip fracture. Structured instruments were used to interview and observe the patients on four occasions during the hospital stay. The patients’ experiences of physical pain decreased during the hospital stay. Physical pain at rest was lower than pain with movement. Patients who scored physical pain as more intense (group B) during the visit to the hospital had significantly more unfavourable experiences in the sensory, emotional, and existential dimensions the day before discharge from the hospital compared with the patients who scored pain as less intense (group A). The patients in group B perceived the interventions as less favourable than group A. Furthermore, group B had more intense physical pain in the ambulance than the patients in the other group. More patients in group B than in group A had additional health problems.  相似文献   
93.
目的:观察舒降之(辛伐他汀)20mg每日一次降脂的临床疗效。方法:选35例老年高脂血症患者接受舒降之20mg,每日1次(晚上顿服)治疗,疗程8周。观察治疗前后血清总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)。结果:治疗8周后,血清TC、TG、LDL-C较入组前分别降低了29.20%、24.75%、32.87%(均P〈0.01),其中,降低TC的总有效率为93.54%、降低TG的总有效率为59.26%。HDL-C较入组前升高了14.12%(P〈0.01),升高HDL-C的总有效率为54.54%。结论:舒降之20mg,每日1次服用,安全有效,对改善老年人高脂血症有显著疗效。  相似文献   
94.
中老年人膳食和体液免疫水平的调查   总被引:1,自引:0,他引:1  
黄作能  韦江 《卫生研究》1994,23(4):228-230
作者调查了161例(男:98,女:63)中老年人的营养素摄入量、血浆蛋白及体液免疫水平。结果:该人群的大部分人热能的摄入量达RDA值;膳食蛋白质、维生素A、B2、C、锌和铁的摄入量较低;脂肪摄入量按热能比高于30%者约占30%;血浆总蛋白、球蛋白水平较低,尤其是女性;免疫球蛋白IgA偏低,IgG和IgM偏高。  相似文献   
95.
目的 :探讨老年人腹腔镜胆囊切除术的安全性、可行性及注意点。方法 :对 172例老年人胆囊良性病变进行腹腔镜胆囊切除术。其中伴有并存病 96例 (5 5 .81% )。结果 :172例病人均恢复良好 ,无并发症发生 ,无中转开腹病例。结论 :只要做好围手术处理 ,老年人行腹腔镜胆囊切除术是安全可行的。  相似文献   
96.
目的:探讨健康人携带的白喉棒状杆菌的生物学特性及其与标准的产毒菌株的生物学性状的差异。方法:采用鸡蛋斜面培养基,亚碲酸钾血琼脂平板和肉汤培养基观察其生长特性,测定多种系列化反应性,毒力和药物敏感性。结果:健康人携带的白喉杆菌的培养特性典型均无毒力;发酵麦芽糖和发酵蔗糖的菌株较多,有较多的耐麦迪霉素,苯唑青霉素和洁霉素的菌株。结论:健康人所携带的白喉杆菌的生物学特性不同于标准的有毒力的菌株。  相似文献   
97.
目的探讨50岁以上正常人左室舒张期脉冲多普勒频谱的参数变化情况。方法选择一年半时间内受检的所有50岁以上正常人475例,按每10岁为一组分4组进行分析。受检者取左侧卧位,常规显示心尖四腔心切面,取样容积置于二尖瓣尖,使声束与二尖瓣血流方向夹角<15°,以连续三个心动周期的平均值分别测量E峰、A峰、E/A及E峰减速时间并统计。结果发现E峰高于正常值低限的例数、平均E峰血流速度以及E/A均随着年龄的增加而下降,E峰减速时间则随着增龄而增加。结论左室舒张期血流频谱的所有参数与年龄有显著的相关性,明显随着增龄而变化,并且有其规律性。  相似文献   
98.
In order to establish the safety and efficacy of fluoxetine in subjects over 60 years of age with Type 2 diabetes, a randomized, double-blind, parallel study of 30 obese subjects was undertaken, comparing the use of fluoxetine 60 mg daily with placebo. Subjects were diet controlled with an HbA1 < 14% (reference range 6–9%) and BMI > 29 kg m2. Those taking fluoxetine had a median weight loss of 2.6 kg at 3 months (p < 0.001) and 3.9 kg at 6 months (p < 0–02), compared with weight loss in the placebo group of 0.1 kg and 0.0 kg at 3 and 6 months, respectively. Improved glycaemic control was also demonstrated in the fluoxetine group compared with placebo, initial HbA1 levels of 8.0% vs 8.7% (NS) falling at 4 months by 0.9% (p < 0.02) and at six months by 0.9% (p < 0.02). No sustained improvement in fasting blood glucose levels was demonstrated. Reporting of adverse events was similar in both groups. Fluoxetine in the short term aids weight loss and improves glycaemic control without a significant increase in adverse events in elderly Type 2 diabetic subjects.  相似文献   
99.
100.
Impairment of bone turnover in elderly women with hip fracture   总被引:4,自引:0,他引:4  
Summary Hip fracture is one of the most severe consequences of osteoporosis affecting aged women. However, abnormalities of bone turnover responsible for bone loss in this condition have not been clearly defined. To further evaluate the bone metabolic status of women sustaining hip fracture, we have prospectively measured serum osteocalcin as a marker of bone formation and urinary excretion of pyridinoline (Pyr) and deoxypyridinoline (D-pyr) cross-links as markers of bone collagen degradation in 174 independently living women (80 ± 8 years) within a few hours after a hip fracture. Comparison was made with 77 age-matched controls (80 ± 5 years) and 17 premenopausal women (39 ± 3 years). In addition 15 of the patients were followed with daily measurements during the first postoperative week. At the time of admission osteocalcin was 20% lower in the fractured women compared to the elderly controls (7.6 ± 3.8 vs. 9.5 ± 4.5 nglml,P = 0.001). Pyr and D-pyr were 36% and 40% higher, respectively (P = 0.0001), than in elderly controls and 85% and 76% higher than in premenopausal controls (P = 0.0001). Serum osteocalcin did not correlate with the cortisol level measured at the same time (r = 0.03, ns), nor with serum albumin and creatinine. Serum osteocalcin remained unchanged within 18 hours after fracture, whereafter it progressively decreased until the third postoperative day. No correlation was noted between the excretion of pyridinoline cross-links and the time elapsed from fracture.These data suggest that the abnormal levels of osteocalcin and pyridinolines are unrelated to traumatically induced acute changes, but reflect abnormalities of bone turnover existing prior to the fracture. Thus, hip-fracture patients have biochemical evidence of decreased bone formation and increased bone resorption when compared to age-matched controls. We suggest that these abnormalities may play a role in the decrease of the bone mass and the consequently increased bone fragility that characterize the osteoporotic hip fracture in the elderly.  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