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   242398篇
  免费   276598篇
  国内免费   36923篇
耳鼻咽喉   2451篇
儿科学   4149篇
妇产科学   2273篇
基础医学   87669篇
口腔科学   2338篇
临床医学   58132篇
内科学   92862篇
皮肤病学   4648篇
神经病学   21916篇
特种医学   8634篇
外科学   40924篇
综合类   51727篇
一般理论   2篇
预防医学   41243篇
眼科学   18334篇
药学   57806篇
  3篇
中国医学   46680篇
肿瘤学   14128篇
  2020年   5880篇
  2019年   13155篇
  2018年   13706篇
  2017年   14376篇
  2016年   12943篇
  2015年   12822篇
  2014年   12553篇
  2013年   12438篇
  2012年   12284篇
  2011年   13925篇
  2010年   16672篇
  2009年   24555篇
  2008年   11913篇
  2007年   8367篇
  2006年   7834篇
  2005年   7845篇
  2004年   9899篇
  2003年   9092篇
  2002年   9358篇
  2001年   11263篇
  2000年   6832篇
  1999年   12108篇
  1998年   13636篇
  1997年   13567篇
  1996年   14626篇
  1995年   14870篇
  1994年   14628篇
  1993年   13416篇
  1992年   12683篇
  1991年   12088篇
  1990年   11069篇
  1989年   10920篇
  1988年   10491篇
  1987年   9846篇
  1986年   9382篇
  1985年   8456篇
  1984年   6540篇
  1983年   6554篇
  1982年   7606篇
  1981年   7150篇
  1980年   6818篇
  1979年   6647篇
  1978年   5828篇
  1977年   6128篇
  1976年   5753篇
  1975年   5491篇
  1974年   5046篇
  1973年   4765篇
  1972年   4770篇
  1971年   4102篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
BACKGROUND: Stress has become an increasingly common presentation in general practice. This may relate to an increase in stress in people's lives or a change in the meaning of stress and its conceptualisation as a legitimate problem for the GP. AIM: To explore patients' beliefs about stress, their association with help-seeking behaviour, and to examine differences by ethnic group. DESIGN OF STUDY: Cross-sectional survey of general practice patients attending to see their GP. SETTING: An inner-city London practice. METHOD: Consecutive general practice patients completed a questionnaire, which involved rating a series of symptoms for the extent to which they were associated with stress and describing their help-seeking behaviour. In total, 548 patients completed the questionnaire. Most patients described themselves as black Caribbean (n = 163), black African (n = 48), or white British (n = 187). RESULTS: The symptoms most frequently associated with stress were sleeping problems, feeling depressed, feeling panicky, having high blood pressure and feeling anxious; feeling ashamed, experiencing indigestion, having diarrhoea, feeling hot or cold, and suffering from constipation were least commonly associated to stress. This model of stress did not vary by ethnic group. Ethnic group differences were found for the association between the model of stress and help-seeking behaviour. Although white British patients consistently reported that the more a symptom was seen as indicative of stress, the more likely they would be to visit the doctor for that symptom, this association was not found for either black Caribbean or black African patients. CONCLUSIONS: The belief that stress-related symptoms are a legitimate problem for the GP is not universal and varies according to ethnic group. Stress is used by different patients in different ways and offers a variable pathway to the doctor.  相似文献   
102.
BACKGROUND: It has been suggested that herpes zoster may be a marker for occult malignancy. AIM: To examine the emergence of a subsequent cancer diagnosis in patients with and without herpes zoster. DESIGN OF STUDY: Retrospective cohort study. SETTING: Results were based on the database of Intego, an ongoing Belgian general practice-based morbidity registry, covering 37 general practitioners and including about 311 000 patient years between the years 1994 and 2000. METHOD: Survival analysis comparing the emergence of malignancy in patients with and without herpes zoster. RESULTS: The number of patients below the age of 65 years with herpes zoster, cancer or both was too low to draw any sensible conclusions. Above the age of 65 years we identified a significant increase of cancer emergence in the whole group and in females (hazard ratio = 2.65, 95% confidence interval = 1.43 to 4.90), but not in males. No difference could be identified in the first year after the herpes zoster infection. CONCLUSION: Our results do not justify extensive testing for cancer in herpes zoster patients. The association we identified, however, leaves open a number of questions with respect to the physiopathology behind it.  相似文献   
103.
104.
BACKGROUND: There is a high non-attendance rate for traditional clinic-based routine asthma care in general practice. Alternative methods of providing routine asthma care need to be examined. AIM: To examine the cost and effectiveness of targeted routine asthma care in general practice using telephone triage, compared to usual clinic care. DESIGN OF STUDY: An open randomised controlled trial. SETTING: A single semi-rural practice in the southwest of England. METHOD: Adult patients with asthma were randomised to receive either their routine asthma care in the surgery or care by telephone triage. Asthma control parameters, health status and NHS resource utilisation were measured over the 12-month study period. RESULTS: One hundred and ninety-four patients were randomised and 35% per cent more patients (n = 84 versus n = 62) received more than one consultation in the telephone group. Asthma control as measured by the asthma control questionnaire (ACQ) was similar in the clinic and telephone groups: mean change in ACQ = -0.11 (95% CI = -0.32 to 0.11) versus -0.18 (95% CI = -0.38 to 0.02). Mean NHS costs were 210 pounds sterling per patient per year in the telephone group compared to 334 pounds sterling in the clinic group (P-value of bootstrapped difference = 0.071). CONCLUSION: Targeted routine asthma care by telephone triage of adult asthmatics can lead to more asthma patients being reviewed, at less cost per patient and without loss of asthma control compared to usual routine care in the surgery.  相似文献   
105.
106.
We found multimolecular antigenic mimicry of arthritogenic autoantigens and peptides from several other “self” or foreign antigens sharing amino acid sequence homologies. Many of these new mimotopes induced arthritis and/or uveitis upon immunization in Lewis rats, indicating a role for multiple antigens in the initiation of a certain autoimmune disease.  相似文献   
107.
We have used a three-dimensional diffusion model of calcium entering the presynaptic nerve terminal through discrete channels to simulate experiments relating transmitter release to presynaptic calcium current. The relationship will be less than linear, or will curve downward, if calcium channels are well separated. It will resemble a power-law function with exponent less than the cooperativity of calcium action if channels are clustered closer together. Large presynaptic depolarizations elicit more release than small depolarizations admitting the same calcium influx. This occurs because large pulses open more channels near each other, with the result that the calcium concentration near release sites is greater, due to overlap of calcium diffusing from adjacent channels.  相似文献   
108.
Summary The olfactory epithelium of the adult hamster (Mesocricetus auratus) was examined with the scanning electron microscope following olfactory nerve axotomy. Axotomy results in retrograde degeneration of mature olfactory neurons. Maximum degeneration was observed around day 4. During the degeneration period the epithelium consists primarily of supporting and basal cells. Microvillar columnar supporting cells were observed to have fine cellular processes extending from their lateral border to neighbouring cells. Supporting cells extended to the basal lamina where they terminated in foot-like processes of variable shapes (club, splay and hook). Basal cells which gave rise to new replacement olfactory neurons were observed near the basal lamina. They had a rough cellular surface covered with small granules and fine cellular extensions. Bowman's gland duct cells extended unbranched through the epithelium where they formed funnel duct openings covered with microvilli. During early recovery periods (5–30 days) the number of olfactory neurons in the lower epithelium region increased. We observed olfactory neurons with developing axon and dendritic processes. Specialized growth cone structures were seen at the tips. Olfactory neuron growth cones were elongated or club-shaped and had a ruffled membrane surface. Several thin filopodia extended from the growth cone and made contact with adjacent cells. At late recovery periods (35–120 days) there was a marked increase in the number of olfactory neurons within the middle and lower epithelium regions. Numerous dendritic processes extended to the epithelial surface and terminated in knob-like ciliated structures. Olfactory axons passed basally, forming small intra-epithelial bundles that penetrated the basal lamina then fasciculated into larger bundles within the lamina propria.This study provides detailed three-dimensional observations of the olfactory epithelium following neuron injury, and describes neural degenerative changes, replacement of olfactory neurons, development and maturation. In addition, we describe the structure and basal attachment of supporting cells and their glial-like relation with olfactory neurons.  相似文献   
109.
Summary:  Three chromosomal rearrangements: a balanced reciprocal translocation, t(14;10) (q22;q13), a Y-autosome translocation, t(Y;16) (q11;p13) and a deleted Y chromosome, Yq- were detected among 100 infertile men. The autosomal translocation, associated with oligozoospermia was found to be familial with various effects on the female carriers and the proband's father. The patients with the chromosome Y abberations were found to be azoospermic and might have lost the genes necessary for normal sperma-togenesis.
Zusammenfassung:  Unter 100 infertilen Männern wurden drei Chromosomenneuan-ordnungen entdeckt: eine balancierte reziproke Translokation, t(14;10) (q22;q13), eine Y-autosome Translokation, t(Y;16) (q11;p13) und eine Deletion des Y-Chromosoms, Yq-. Die autosomale Translokation bei Oligozoospermie zeigte sich familiär mit verschiedenen Auswirkungen bei den weiblichen Überträgern und dem Vater des Probanden. Die Patien-ten mit chromosomalen Y-Aberrational wiesen eine Azoospermie auf und scheinen die zur normalen Spermatogenese notwendigen Gene verloren zu haben.  相似文献   
110.
We tested whether hypoglycemia, like hypoxia, would preferentially destroy GABAergic nerve cells in the neocortex. To this end, rat neocortex explants dissected from 6-day-old rat pups and cultured up to a developmental stage approximately comparable to that of the newborn human neocortex, were exposed to hypoglycemia for different periods. Quantitative light microscopic and immunocytochemical evaluation of the cultures demonstrated that hypoglycemia does not preferentially destroy GABAergic but rather non-GABAergic neurons, a finding quite opposite to what was found after hypoxia. Recent biochemical data from other laboratories which seem to support this difference in neuronal vulnerability are discussed. It is concluded that perinatal hypoglycemia may not form such a serious threat with respect to the genesis of epilepsy as does hypoxia.  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