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   72140篇
  免费   2799篇
  国内免费   593篇
耳鼻咽喉   436篇
儿科学   879篇
妇产科学   654篇
基础医学   7995篇
口腔科学   3674篇
临床医学   5853篇
内科学   13445篇
皮肤病学   1412篇
神经病学   5764篇
特种医学   1807篇
外国民族医学   1篇
外科学   12822篇
综合类   3638篇
现状与发展   1篇
一般理论   15篇
预防医学   6665篇
眼科学   1234篇
药学   4405篇
  18篇
中国医学   2601篇
肿瘤学   2213篇
  2023年   781篇
  2022年   1302篇
  2021年   2389篇
  2020年   1481篇
  2019年   5418篇
  2018年   5632篇
  2017年   3648篇
  2016年   1228篇
  2015年   1192篇
  2014年   2043篇
  2013年   2447篇
  2012年   1688篇
  2011年   1922篇
  2010年   1648篇
  2009年   1350篇
  2008年   1399篇
  2007年   1297篇
  2006年   1137篇
  2005年   931篇
  2004年   814篇
  2003年   792篇
  2002年   579篇
  2001年   635篇
  2000年   492篇
  1999年   466篇
  1998年   300篇
  1997年   296篇
  1996年   261篇
  1995年   250篇
  1994年   213篇
  1993年   171篇
  1992年   182篇
  1991年   157篇
  1990年   116篇
  1989年   127篇
  1988年   114篇
  1987年   110篇
  1985年   2851篇
  1984年   3400篇
  1983年   2880篇
  1982年   3337篇
  1981年   3035篇
  1980年   2524篇
  1979年   2507篇
  1978年   2070篇
  1977年   1534篇
  1976年   2001篇
  1975年   1516篇
  1974年   1327篇
  1973年   1275篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
The major allergens present in mouse skin, serum, and urine have been identified. Skin extracts, serum, and urine were chromatographed, and the activities of the fractions were monitored by histamine release from the leukocytes of individuals sensitive to mice. Fractionation of skin extracts revealed two major allergens. The large allergen has a molecular weight of approximately 67,000 daltons and by biochemical and immunochemical criteria appears to be identical to mouse albumin. The smaller molecular weight allergen is approximately 17,000 daltons. The same two allergens are also found in mouse serum and mouse urine. Histamine release by leukocytes of individuals allergic to mice demonstrated that some individuals react predominantly to the large allergen, some to the small allergen, and one group of patients reacts to both allergens.  相似文献   
82.
A family history study of second-degree relatives of 19 patients with anxiety neurosis (panic disorder) and 19 controls showed a morbidity risk of 9.5% among the former compared with 1.4% among the latter. These risks were approximately half those found among first-degree relatives. Female relatives were at higher risk for anxiety neurosis. The risk for other psychiatric illnesses did not differ between the relatives of anxiety neurosis and controls.  相似文献   
83.
84.
85.
Previous investigators have reported a high prevalence of depressive symptoms in drug-dependent patients. Given the responsiveness of depressive disorders to both psychological and pharmacological treatments, it is desirable to find an economical, efficient screening instrument to detect depressive disorders in this population. In this study, 6 depression symptom screening scales (Beck Depression Inventory, Hamilton Depression Scale, Raskin Depression Scale, Degree of Illness Rating, Symptom Checklist 90 Overall, and Depression Subscale) based on either clinician interview or patient self report, were compared according to their utility in detecting cases of depression among 64 applicants for treatment at a substance abuse treatment unit of a community mental health center. The criteria for a case of depression were the Research Diagnostic Criteria (RDC) which are specified and operationalized. Cases identified using previously described cutoff scores on the screening scales were compared to rates based on the RDC and sensitivity and specificity were determined. The results showed that: (1) although the sensitivity of the symptom scales was applicable, ranging from 65--94%, the specificity was less impressive, ranging from 39--61%, and (2) the Beck Depression Inventory, a 13-item patient self report was the most sensitive and specific and is recommended for screening drug-dependent populations for depression.  相似文献   
86.
Summary The slow potential change (spc) accompanying spreading depression (SD) was studied in rats and in a seizure-sensitive strain of Mongolian gerbil under three different experimental paradigms, each involving the use of naloxone. Gerbils undergoing electroconvulsive shock treatment displayed SD during the post-ictal phase, which was blocked by the intraperitoneal (i.p.) administration of naloxone (20–50 mg kg-1). Topical application of naloxone to the exposed cortex of the anaesthetized gerbil and rat blocked the spc of SD evoked by KCl. Microiontophoretic ejection of naloxone during extracellular recordings reversed cell refractoriness following the spc, demonstrated by the observation of a maintained sensitivity to iontophoretic pulses of glutamate. The results suggest a possible involvement of naloxone-sensitive processes in the mechanism responsible for cortical SD.  相似文献   
87.
Nagy E  Dobos P 《Virology》1984,137(1):58-66
Both dsRNA genome segments of Drosophila X virus (DXV) were denatured and translated in vitro using nuclease-treated rabbit reticulocyte lysates. The synthesis of all four primary gene products was detected by polyacrylamide gel electrophoresis and autoradiography. Genome segment A (mol wt 2.3 X 10(6)) encoded polypeptides with molecular weights of 67,000 (67K), 34K, and 27K, whereas segment B (mol wt 22 X 10(6)) encoded the 110K polypeptide. The proteolytic processing of 67K which generates a 49K polypeptide in infected cells was also observed in vitro. Pulse-chase experiments indicated that synthesis of the three polypeptides encoded by genome segment A initiated independently and simultaneously, suggesting that segment A is polycistronic. Native (undenatured) DXV dsRNA could also be translated with high fidelity (vitro). The messenger activity of native dsRNA was abolished by S1 nuclease treatment but completely restored on subsequent denaturation. In vitro "pulse-chase" experiments using native dsRNA as messenger, indicated that the order of translation of polypeptides on genome segment A was 5'-67K-27K-34K-3'.  相似文献   
88.
Chronic immunization may lead to the production of circulating immune complexes (CICs). This study was undertaken to determine the presence of circulating IgG immune complexes in 95 subjects with allergic rhinitis/asthma receiving immunotherapy, 46 individuals with similar diagnosis but not on immunotherapy, and 64 healthy controls. Modified Raji cell and murine leukemia cell (L-1210) assays, selected for a high density of Fc receptors and devoid of Epstein-Barr virus membrane antigen, were used. Other immunological parameters such as immunologlobulins G, A, M, E, and rheumatoid factor activity were also studied. The CIC concentrations in the treated group did not differ significantly from the untreated group, although both groups did have a significantly higher concentration than the healthy controls. The presence of CICs has no relationship with age or sex of patients, dosage of allergen administered, number and nature of allergens received, period between the time of last injection and the blood sampling, and the duration of immunotherapy. Serum IgG, IgA, IgM, and rheumatoid factor activity did not differ between the treated and untreated groups. IgE was significantly higher in the treated group when compared with the untreated, and IgE levels in treated patients with elevated CICs were significantly increased compared with CIC-negative treated patients. These data suggest that CICs are present in serum of atopic diseases such as allergic rhinitis/asthma. Significantly, an association of elevation of CICs with immunotherapy could not be demonstrated.  相似文献   
89.
Renal carcinoma developed in two or more members of nine families. Multiple generations were affected in five kindreds, and siblings in four. The median age at cancer diagnosis was a decade earlier than usual, and individual patients had bilateral or multifocal lesions; these are features of hereditary forms of diverse cancers. No patient had von Hippel-Lindau disease or other predisposing genetic syndromes. Karyotypes of the peripheral blood of nine persons showed no instance of a 3;8 chromosome translocation as recently reported in association with renal carcinoma in ten members of one family. The findings show that familial renal cancer is more common than previously reported in the literature.  相似文献   
90.
BACKGROUND: Attendance for routine asthma reviews is poor. A recent randomised controlled trial found that telephone consultations can cost-effectively and safely enhance asthma review rates; however, concerns have been expressed about the generalisability and implementation of the trial's findings. AIM: To evaluate the effectiveness of a telephone option as part of a routine structured asthma review service. DESIGN OF STUDY: Phase IV controlled before-and-after implementation study. SETTING: A large UK general practice. METHOD: Using existing administrative groups, all patients with active asthma (n = 1809) received one of three asthma review services: structured recall with a telephone-option for reviews versus structured recall with face-to-face-only reviews, or usual-care (to assess secular trends). Main outcome measures were: proportion of patients with active asthma reviewed within the previous 15 months (Quality and Outcomes Framework target), mode of review, enablement, morbidity, and costs to the practice. RESULTS: A routine asthma review was provided for 397/598 (66.4%) patients in the telephone-option group compared with 352/654 (53.8%) in the face-to-face-only review group: risk difference 12.6% (95% confidence interval [CI] = 7.2 to 17.9, P<0.001). The usual-care group achieved a review rate of 282/557 (50.6%). Morbidity was equivalent in the three groups; however, enablement (P = 0.03) and confidence (P = 0.007) in asthma management were greater in the telephone-option versus face-to-face-only group. The cost per review achieved by providing the telephone-option service was lower than the face-to-face-only service (10.03 pounds versus 12.74 pounds, mean difference 2.71 pounds; 95% CI = 1.92 to 3.50, P<0.001); usual-care costs were 11.85 pounds per review achieved. CONCLUSION: Routinely offering telephone reviews cost-effectively increased asthma review rates, enhancing patient enablement and confidence with management, with no detriment to asthma morbidity. Practices should consider a telephone option for their asthma review service.  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