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   64811篇
  免费   7011篇
  国内免费   1855篇
耳鼻咽喉   443篇
儿科学   1601篇
妇产科学   1438篇
基础医学   4539篇
口腔科学   1568篇
临床医学   7267篇
内科学   10772篇
皮肤病学   797篇
神经病学   4059篇
特种医学   1016篇
外国民族医学   11篇
外科学   6103篇
综合类   10059篇
现状与发展   8篇
一般理论   1篇
预防医学   11064篇
眼科学   1126篇
药学   4267篇
  51篇
中国医学   1662篇
肿瘤学   5825篇
  2024年   278篇
  2023年   1314篇
  2022年   2742篇
  2021年   3573篇
  2020年   3398篇
  2019年   2501篇
  2018年   2450篇
  2017年   2574篇
  2016年   2872篇
  2015年   2683篇
  2014年   4893篇
  2013年   5334篇
  2012年   4452篇
  2011年   4522篇
  2010年   3495篇
  2009年   3159篇
  2008年   3020篇
  2007年   2930篇
  2006年   2587篇
  2005年   2208篇
  2004年   1790篇
  2003年   1580篇
  2002年   1318篇
  2001年   1136篇
  2000年   953篇
  1999年   747篇
  1998年   682篇
  1997年   610篇
  1996年   468篇
  1995年   435篇
  1994年   409篇
  1993年   318篇
  1992年   318篇
  1991年   296篇
  1990年   230篇
  1989年   203篇
  1988年   174篇
  1987年   137篇
  1986年   130篇
  1985年   148篇
  1984年   122篇
  1983年   79篇
  1982年   88篇
  1981年   73篇
  1980年   57篇
  1979年   51篇
  1978年   30篇
  1977年   26篇
  1976年   35篇
  1975年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Four hundred and six consecutive suicide attempts made by 15-19 year-old adolescents in 1973-1982 were examined. Two hundred and twenty-six cases were first, 180 repeated suicide attempts. Repeaters came from poorer social situations and less well integrated families than first-timers. Repeaters had many adapting problems typical of personality disorders and had previously been in psychiatric treatment. Their level of adaptive functioning (GAS) and overall functioning (DSM III: s axis V) were poorer than within first-timers. They were not psychotic more often than first-timers and did not make more difficult suicide attempts. Their psychiatric after-care was more intensive and prognosis with regard to subsequent suicide was poorer than within first-timers. At the end of follow-up time (approx. 5 years) 1% of first-timers and 4% of repeaters had committed suicide. Observed-expected ratio for first-timers was 0.58 and for repeaters 1.73.  相似文献   
62.
Background: The prevalence of respiratory diseases in smokers and nonsmokers and the incidence of perioperative respiratory events (PREs) were investigated for patients undergoing general anaesthesia. The aim was to quantify well-known problems and to identify possible new associations between smoking and PREs.
Methods: From July 1992 to December 1994, risk factors, demographic data, and PREs were documented by an automatically readable anaesthetic record (ARAR). PREs were used as defined by the German Society of Anaesthesiology and Intensive Care.
Results: Of 26 961 subsequent anaesthesias in adults, 7122 (26.4%) were performed in smokers with a prevalence of chronic bronchitis of 23.3% (4.8% in nonsmokers). 1573 PREs occurred in 1397 (5.2%) of all anaesthetics. 459 events concerned intubation problems and problems in technical airway management. 1114 specific respiratory events (SPREs) like re-intubation, laryngospasm, bronchospasm, aspiration, hy-poventilation/hypoxaemia and others had a total incidence of 5.5% in smokers and 3.1% in nonsmokers. The relative risk (RR) of SPREs was 1.8 in all smokers, 2.3 in young (16–39 years) smokers, and 6.3 in obese young smokers. The RR of perioperative bronchospasm was 25.7 in young smokers with chronic bronchitis.
Conclusion: The impact of smoking on perioperative respiratory problems should make anaesthetists take this widespread preoperative condition seriously, particularly in young adults. The presented method of incident reporting (based on a national classification) could contribute to future research in anaesthetic epidemiology.  相似文献   
63.
Summary Thirty adult patients presenting with medulloblastoma between 1974 and 1991 were studied and treated at Puerta de Hierro Clinic. After diagnosis, all patients were treated by surgery followed by radiotherapy and eight of them received adjuvant chemotherapy. We have studied the influence of some factors such as age, sex, location of tumour in the cerebellum, amount of surgical resection and histological variants on survival and recurrence of the disease. Only the histological type has a statistically significant influence on survival and recurrence: we have found that patients presenting classic medulloblastoma have a long survival and a long relapse-free interval.  相似文献   
64.
Hypertension, a major risk factor for cardiovascular diseases, is thought to be inherited to some extent. However, the nature of its genetic component remains unresolved. In the present study, data from a single large kindred (the HGAR1 pedigree) were used to search for evidence of single gene and multifactorial effects on diastolic blood pressure. Commingling analyses found that a mixture of three distributions fit the data significantly better than a single normal distribution, suggesting a major effect influencing diastolic blood pressure levels. However, segregation analysis, using regressive models, indicated that the transmission probabilities were not consistent with Mendelian expectations. There was no evidence of either major gene or polygenic effects on diastolic blood pressure levels in this family. © 1993 Wiley-Liss, Inc.  相似文献   
65.
To define the prevalence of cardioembolic sources found by transesophageal echocardiography (TEE) in different age groups of patients with and without cryptogenic systemic embolism, TEE risk factors for cardiogenic embolism were identified from 341 consecutive patients referred for TEE. One hundred and thirty-five had cryptogenic cerebral or systemic peripheral embolic events (CEE) and 206 other indications for TEE (CTR). Cardioembolic sources were found in 40% of CEE and in 29% of CTR (P < 0.02). Specifically, left atrial (LA) thrombi (P < 0.0001), atrial septal aneurysm with right-to-left shunt (P < 0.002), and atherosclerotic aortic plaques (P < 0.02) were more frequent. The prevalence of potential cardioembolic sources was significantly higher in patients ≥ 70-years old than in younger patients (P < 0.03), specifically LA thrombi (P < 0.004) and atherosclerotic aortic plaques (P < 0.0001). In patients ≥ 70-years old, potential cardioembolic sources were found in 63% and in 40% in CEE and CTR (P = 0.073), respectively. However, LA thrombi were more frequent in CEE (P < 0.003). Thus, potential cardioembolic sources observed by TEE are found more frequently in patients ≥ 70-years old than in younger patients. LA thrombi were more frequent in CEE than in CTR patients ≥ 70-years old. In patients ≥ 70-years old with CEE who are eligible for an anticoagulant regimen, a search for potential cardioembolic sources by TEE should be considered.  相似文献   
66.
对28例Graves病的可溶性白介素2受体(sIL2R)和各种甲状腺激素以及甲状腺自身抗体治疗前后比较,并进行逐步回归,结果表明:治疗后Graves病患者除TSH外,各种甲状腺激素及甲状腺自身抗体显著降低(P<001),并对sIL2R的上升与下降呈显著相关。  相似文献   
67.
Abstract For over 30 years now, research has been carried out to isolate and purify bone morphogenettc protein (BMP), a substance which has been shown to induce heterotopic bone formation in various animal species. Recent advances in the fields of developmental biology, molecular biology, genetics and wound healing, have shown that the BMPs are not only responsible for postfetal bone induction (including normal bone remodeling, healing and repair), but are also critical during embryogenesis, not only in regards to the skeletal system, but quite possibly in the morphogenesis and pattern formation of other tissues and organs as well, Therefore. BMPs have the potential as a therapeutic utility in orthopedic and dento-alveolar reconstruction.  相似文献   
68.
69.
70.
Abstract. Both transforming growth factor-β (TGF-ß) and platelet-derived growth factor (PDGF) have been shown to affect cell proliferation in vitro. The hypothesis being tested was that the effects of the 2 cytokines would be modulated by the presence of serum in the medium. Gingival fibroblasts, obtained from periodontally healthy patients, were maintained in primary culture. Dose response experiments were performed for each growth factor in serum-free medium and in medium containing natural or heat-inactivated fetal bovine serum (10% FBS). Changes in cell numbers were quantified by crystal violet staining. The optimal concentrations of the individual factors (10 ng/ml TGF-ßI, 20 ng/ml PDGF-BB) were then used when the 2 factors were tested in various sequences. In serum-free medium or in medium with 10% natural serum, the response to PDGF-BB was dose-dependent up to 40 ng/ml; however, with 10% heat-inactivated serum, the maximal response was seen at 20 ng/ml. The largest increase in cell numbers was produced by the simultaneous exposure to the two cytokines, rather than a sequential presentation. The findings suggest that the 48-h growth response of human gingival fibroblasts to 10 ng/ml TGF-ß1 or 20 ng/ml PDGF-BB in serum-free medium was equivalent to growth obtained in medium containing heat-inactivated 10% FBS without added growth factors.  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