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   916篇
  免费   53篇
  国内免费   1篇
耳鼻咽喉   3篇
儿科学   22篇
妇产科学   14篇
基础医学   126篇
口腔科学   21篇
临床医学   123篇
内科学   224篇
皮肤病学   38篇
神经病学   63篇
特种医学   94篇
外国民族医学   1篇
外科学   63篇
综合类   45篇
预防医学   32篇
眼科学   6篇
药学   56篇
中国医学   1篇
肿瘤学   38篇
  2022年   16篇
  2021年   18篇
  2020年   12篇
  2019年   17篇
  2018年   23篇
  2017年   13篇
  2016年   13篇
  2015年   23篇
  2014年   24篇
  2013年   31篇
  2012年   26篇
  2011年   34篇
  2010年   42篇
  2009年   40篇
  2008年   28篇
  2007年   31篇
  2006年   31篇
  2005年   24篇
  2004年   22篇
  2003年   22篇
  2002年   17篇
  2001年   13篇
  2000年   17篇
  1999年   13篇
  1998年   25篇
  1997年   19篇
  1996年   27篇
  1995年   22篇
  1994年   27篇
  1993年   30篇
  1992年   22篇
  1991年   11篇
  1990年   8篇
  1989年   20篇
  1988年   15篇
  1987年   11篇
  1986年   8篇
  1985年   14篇
  1983年   9篇
  1982年   11篇
  1981年   11篇
  1980年   11篇
  1979年   12篇
  1978年   7篇
  1977年   9篇
  1957年   9篇
  1955年   6篇
  1954年   6篇
  1949年   8篇
  1948年   8篇
排序方式: 共有970条查询结果,搜索用时 31 毫秒
71.
There are many obstacles in undertaking psychological burns research with children and adolescents, and the more useful longitudinal studies are particularly fraught with difficulty. This work introduces and discusses the problems of attrition and nonparticipation encountered in our attempt to use a rigorous design and methodology to study this population. The aim is to provide the impetus for a more thorough, detailed review of this problem.  相似文献   
72.
Twenty percent of people endure tinnitus to a degree that their quality of well-being and productivity in life are impaired, and up to 60% report depression. Four measures are widely used to assess tinnitus-related distress, yet the relationship among all four measures or their relationship to relevant psychiatric variables has yet to be studied. This study assessed the association between the four commonly used measures of tinnitus and their relationship to depressive symptoms, quality of well-being, and internal focus. Sixty-five people with tinnitus completed the following measures: Iowa Tinnitus Handicap Questionnaire (THQ); Tinnitus Reaction Questionnaire (TRQ); Tinnitus Handicap Inventory (THI); Tinnitus Questionnaire (TQ); Hamilton Rating Scale for Depression (HRSD); Beck Depression Inventory (BDI); Quality of Well-Being Scale (QWBS); Modified Somatic Perception Questionnaire (MSPQ); and Private Self-Consciousness Scale (PSCS). All the tinnitus measures were highly intercorrelated (r = .76-.90; all p values < .001), and related to depressive symptoms (r = .48-.66; p < .001) and QWBS (r = .37-.48; all p values < 0.008). The tinnitus measures correlated with the MSPQ (r = .37-.52; all p values < .01) but not with the PSCS. When controlling for the shared variance between tinnitus measures, the THQ independently predicted the HRSD, whereas the TRQ independently predicted the BDI.  相似文献   
73.
74.
The influence of N -ethyl- and N -benzyl-1,2-diphenyl ethanolamines (compounds E and B, respectively) was examined on the spontaneously contracting rabbit jejunum and the rat uterus together with their influence on the contractions induced by some spasmogens in the guinea-pig ileum and oxytocics and CaCl2in the pregnant rat uterus. Both E and B inhibited the spontaneous contractions of the rabbit jejunum with ID50values of 0.13 and 0.03 μmol ml−1. Their inhibitory activities were not antagonized by α- or β-adrenoceptor blockers but significantly reversed by CaCl2(0.015 μmol ml−1). The compounds also antagonized nicotine, ACh-, histamine-, 5-HT- and CaCl2-induced contractions by 44–100%. Compound E seemed to be several times more potent than B in inhibiting the spontaneous uterine contractions with an ID50of (7 nmol ml−1). Their inhibitory effects were not antagonized by β2-adrenoceptor or H2-receptor blocking drugs. Both compounds (40 nmol ml−1) antagonized in a competitive manner CaCl2-induced contractions in the K+-depolarised uterus and PGE2and oxytocin-induced uterine contractions. The ID50values were in the range of 1.6–10.7 nmol ml−1. The results suggest that E and B compounds may be considered as putative L-Ca2+channel blockers with certain selectivities. The E compound seemed to be more selective against uterine L-Ca2+channels and the B compound against intestinal smooth muscles. Thus, the compounds may be of potential value in treatment of some colics, the irritant bowel syndrome, dysmenorrhoea and premature deliveries. 1999 Academic Press@p$hr  相似文献   
75.
Summary. Haemophilia A is the most common inherited X‐linked recessive bleeding disorder. The aim was to investigate the usefulness of two DNA markers in linkage analysis, one intragenic BCL1 affecting restriction site in intron 18, and is detected as restriction fragment length polymorphism (RFLP), and one extragenic variable number of tandem repeat (VNTR) locus DXS52 (St14) to formulate an informative and accurate carrier detection and prenatal diagnosis. The study included 46 families with at least one child affected with haemophilia A, and 30 unrelated normal females as control group. Polymerase chain reaction (PCR) and restriction enzyme analysis were used to study the polymorphism in BCL1, and long‐distance PCR for detection of VNTR (ST14) alleles. The incidence of BCL1 (+) allele was 74%, 72% and 60% in patients, mothers and control group, respectively. Expected heterozygosity for BCL1 was 40% in mothers of affected cases compared with 48% in the female control group. However, observed heterozygosity was found to be 48% in the mothers of affected cases, compared with 60% in the control group. Thus, 48% of the studied families are informative for this marker alone. Nine different alleles of VNTR (St14) were observed in mothers and six alleles in affected cases and six in the control group. The most prevalent alleles were 1300 bp (45.5% and 34%) and 700 bp (13.6% and 20%) in patients and their mothers, respectively. Observed heterozygosity in mothers was 41% compared with 43.3% in controls. The combined use of both BCL1 and St14 markers raised the informative rate to 63.6%. Carrier detection and prenatal diagnosis is possible in haemophilia A families using both DNA markers. We suggest screening haemophilic families first for BCL1 polymorphism followed by analysis of St14 locus.  相似文献   
76.
This study is a meta-analytic review of the behavioral adjustment of children and adolescents with asthma. Of 78 studies initially reviewed, 26 studies (encompassing 28 data sets), reflecting data on nearly 5,000 children with asthma (mean age = 8.4 years; 40% female), met criteria for inclusion. Effect size estimates were calculated across studies using standard methods. Separate effect sizes were calculated for internalizing and externalizing behavioral problems, degrees of asthma severity, and differences in control group used (i.e., sample controls or normative data). Results indicate that children with asthma have more behavioral difficulties than do healthy children, with the effect for internalizing behaviors being greater than that for externalizing behaviors (d(mn) = .73 vs .40). Increased asthma severity was associated with greater behavioral difficulties. Results did not differ by comparison group (healthy controls vs normative data). The findings suggest that patients with asthma, particularly children with severe asthma, should be considered at higher risk for behavioral difficulties that may necessitate psychosocial intervention.  相似文献   
77.
78.
Background: Osteoporosis (OP) is a growing health problem not only in women but also in men. Subjects and methods: This study was carried out on 100 healthy men, age range 30–65 years (mean ± SD, 44.65 ± 8.3). All were randomly recruited from Assiut city during the period January 2005 to January 2006. Complete clinical history included occupational history, smoking habit, physical activity and calcium intake. Complete clinical examination and anthropometric measurments were done. Laboratory investigations for serum calcium, phosphorus and osteocalcin were performed. Bone mineral density (BMD) was measured by calcaneal ultrasound. Results: Sixty‐three percent of participants had normal BMD, 37% had low BMD, (26% had quantitative bone ultrasound [QUS] T‐score –1 to –2.5 and 11% had QUS T‐score ≤ –2.5). Smoking and low physical activity were risk factors for low BMD. Significant positive correlations were found between BMD and body mass index, serum calcium, and osteocalcin and negative correlation with phosphorus. We concluded that low BMD occurs with high frequency in Egyptian men. Smoking, physical inactivity and low body index are significant risk factors. Low serum calcium, low serum osteocalcin and high serum phosphorus are biochemical risk factors of low BMD in males.  相似文献   
79.
Wiener  JI; Chako  AC; Merten  CW; Gross  S; Coffey  EL; Stein  HL 《Radiology》1986,160(2):299-305
We tested a variety of inversion-recovery (IR) and spin-echo (SE) sequences by imaging the breast masses of 22 patients before surgery and 23 tissue specimens with magnetic resonance (MR) imaging at 0.6 T to determine the most effective pulse sequences to evaluate breast disease. An SE pulse sequence using a long repetition time (TR) of 1,600 msec and a long echo time (TE) of 90 msec was found to be the most sensitive in depicting carcinoma in the excised tissue specimens, with all of the carcinomas (n = 15) demonstrating irregular areas of higher signal intensity (SI) than that of the adjacent fat. However, only five of 11 breast carcinomas present in the preoperative patients produced a higher SI than that produced by fat on the same T2-weighted sequence. Five of the remaining six carcinomas in the preoperative patients appeared as localized distortions of fibroductular architecture on both T2-weighted SE and IR sequences. In axillary tissue specimens, both metastatic carcinoma and hyperplastic lymph nodes produced a high SI on T2-weighted SE sequences. However, metastatic carcinoma had a significantly longer T2 relaxation time than did hyperplastic lymph nodes.  相似文献   
80.
The nuclear medicine bleeding scan is frequently insufficient to locate sites of bleeding precisely, in spite of its great sensitivity. A small, hand-held Geiger-Müller counter, placed directly on exposed intestine in the operating room, enables precise location of the probable bleeding site. In three patients, the technique allowed a minimal amount of intestine to be resected, distinguished between large- and small-intestinal hemorrhage, and eliminated other foci as sites of bleeding.  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