全文获取类型
收费全文 | 16328篇 |
免费 | 1458篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 115篇 |
儿科学 | 426篇 |
妇产科学 | 421篇 |
基础医学 | 2380篇 |
口腔科学 | 395篇 |
临床医学 | 1572篇 |
内科学 | 3652篇 |
皮肤病学 | 181篇 |
神经病学 | 1771篇 |
特种医学 | 651篇 |
外国民族医学 | 1篇 |
外科学 | 1878篇 |
综合类 | 276篇 |
一般理论 | 12篇 |
预防医学 | 1512篇 |
眼科学 | 431篇 |
药学 | 1309篇 |
1篇 | |
中国医学 | 17篇 |
肿瘤学 | 820篇 |
出版年
2022年 | 117篇 |
2021年 | 280篇 |
2020年 | 167篇 |
2019年 | 264篇 |
2018年 | 293篇 |
2017年 | 206篇 |
2016年 | 224篇 |
2015年 | 249篇 |
2014年 | 344篇 |
2013年 | 575篇 |
2012年 | 747篇 |
2011年 | 843篇 |
2010年 | 468篇 |
2009年 | 440篇 |
2008年 | 741篇 |
2007年 | 824篇 |
2006年 | 803篇 |
2005年 | 846篇 |
2004年 | 717篇 |
2003年 | 675篇 |
2002年 | 665篇 |
2001年 | 452篇 |
2000年 | 449篇 |
1999年 | 421篇 |
1998年 | 252篇 |
1997年 | 192篇 |
1996年 | 161篇 |
1995年 | 143篇 |
1994年 | 134篇 |
1993年 | 142篇 |
1992年 | 333篇 |
1991年 | 314篇 |
1990年 | 312篇 |
1989年 | 269篇 |
1988年 | 239篇 |
1987年 | 232篇 |
1986年 | 207篇 |
1985年 | 205篇 |
1984年 | 168篇 |
1983年 | 176篇 |
1982年 | 120篇 |
1981年 | 124篇 |
1979年 | 157篇 |
1978年 | 136篇 |
1977年 | 125篇 |
1976年 | 132篇 |
1975年 | 124篇 |
1974年 | 120篇 |
1973年 | 127篇 |
1972年 | 110篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
F T McDermott G Whelan D J St John G L Barnes R Elliott R Herrmann G T Schmidt R A Smallwood 《The Medical journal of Australia》1987,146(10):525, 528-525, 529
Information on the relative incidence of Crohn's disease and ulcerative colitis was obtained by a prospective investigation at six Melbourne teaching hospitals. One hundred and eleven patients who presented with chronic inflammatory bowel diseases between 1980-1981 were admitted to the study. Forty (36%) patients were diagnosed as having Crohn's disease and 63 (57%) patients as having ulcerative colitis. The type of chronic inflammatory bowel disease could not be determined in eight (7%) patients. These findings suggest that the relative frequency of Crohn's disease and ulcerative colitis in Melbourne hospitals is within the range that is reported for northern Europe and the United States. 相似文献
24.
The goals of this report are: 1) to review the number needed to treat (NNT) concept, which, although well established in many sectors of medicine, is still relatively new to the radiotherapy community; 2) to discuss several clinical radiotherapy examples illustrating the inherent advantages of the NNT approach; and 3) to discuss potential future roles of the NNT concept within radiotherapy. 相似文献
25.
Hui-Ju Wen Ying-Chu Lin Yung-Ling Lee Yueliang Leon Guo 《Pediatric allergy and immunology》2006,17(7):489-494
High cord blood immunoglobulin E (cbIgE) is known to be associated with increased risks of atopic diseases in childhood. The relationship between genetic polymorphisms and high cbIgE has not been well documented. A cross-sectional study was conducted to assess the association between cbIgE and genetic polymorphisms of interleukin (IL)-4 -590C/T, the beta-subunit of the high-affinity receptor for IgE (FcepsilonRI-beta) E237G, lymphotoxin (LT)-alphaNcoI alleles, and tumor necrosis factor (TNF)-alpha -308G/A. A total of 320 mother-neonate pairs were recruited from four maternity hospitals from different locations of Taiwan. Cord blood was obtained and assayed for cbIgE. Polymerase chain reaction followed by restriction fragment length polymorphism was used to assess the genotypes. Three hundred pairs of mothers and neonates were included in the final analysis. Infants with IL-4 -590 C allele were found to have higher risk of elevated cbIgE (> or =0.35 IU/ml, 24.3%) (p = 0.004). After adjusting for gender, birth order, maternal age, and history of allergic disease in maternal and paternal families, odds ratios for CC and CT genotypes were 4.41 and 3.16 (95% confidence interval 0.78-22.67, and 1.66-6.13), respectively, using TT genotype as reference. The genotypes of FcepsilonRI-beta, LT-alpha, and TNF-alpha were not associated with cbIgE before or after the adjustment. Our finding suggested a significant association of cbIgE with genetic polymorphism of IL-4 -590C/T, but not with the genotypes of FcepsilonRI-beta, LT-alpha, and TNF-alpha. 相似文献
26.
27.
ABSTRACT: Background: Most women will sustain some degree of trauma to the genital tract after vaginal birth. This study aimed to examine the association between maternal position at birth and perineal outcome in women who had a midwife‐attended, spontaneous vaginal birth and an uncomplicated pregnancy at term. Methods: Data from 3,756 births in a major public tertiary teaching hospital were eligible for analysis. The need for sutures in perineal trauma was evaluated and compared for each major factor studied (maternal age, first vaginal delivery, induction of labor, not occipitoanterior, use of regional anesthesia, deflexed head and newborn birthweight >3,500 g). Birth positions were compared against each other. Subgroup analysis determined whether birth positions mattered more or less in each of the major factors studied. The chi‐square test was used to compare categorical variables. Results: Most women (65.9%) gave birth in the semi‐recumbent position. Of the 1,679 women (44.5%) who required perineal suturing, semi‐recumbent position was associated with the need for perineal sutures, whereas all‐fours was associated with reduced need for sutures; these associations were more marked in first vaginal births and newborn birth weight over 3,500 g. When regional anesthesia was used, semi‐recumbent position was associated with a need for suturing, and lateral position associated with a reduced need for suturing. The four major factors significantly related to perineal trauma included first vaginal birth, use of regional anesthesia, deflexed head, and newborn weight more than 3,500 g. Conclusions: Women should be given the choice to give birth in whatever position they find comfortable. Maternity practitioners have a responsibility to inform women of the likelihood of perineal trauma in the preferred birth position. Ongoing audit of all clinicians attending births is encouraged to further determine effects of maternal birth position and perineal trauma, to investigate women's perception of comfortable positioning at birth, and to measure changes to midwifery practice resulting from this study. 相似文献
28.
1. Opioid receptors have been localised on sensory fibres in the vagus nerve and opioids have previously been shown to inhibit non-adrenergic, non-cholinergic (NANC) neurotransmission in guinea-pig bronchi in vitro and in vivo. We have now investigated whether an inhibitory effect could be demonstrated on cholinergic neurotransmission. 2. Electrical field stimulation (EFS) (8 Hz, 0.5 ms, 40 V for 20 s) produced only a rapid, cholinergic response in the upper trachea but in the lower trachea and main bronchi a cholinergic response which was atropine-sensitive and a longer lasting NANC contraction that was atropine-insensitive was demonstrated. This slow contraction could be blocked by tetrodotoxin and capsaicin pretreatment. 3. [D-Ala2, NMePhe4, Gly-ol5]enkephalin (DAMGO), a selective mu-opioid receptor agonist, inhibited the cholinergic response to EFS at 8 Hz in a dose-dependent manner in main bronchi (IC50 = 113 nM with a maximal inhibition of 35.7 +/- 5.6% 10 microM, n = 5). In the lower trachea, DAMGO inhibited the cholinergic response to a similar extent (inhibition of 35.8 +/- 3.5% at 10 microM, n = 5). However, DAMGO had no effect on the contractile response to exogenously applied acetylcholine in the main bronchi. By contrast, opioids had no inhibitory effect on cholinergic neurotransmission in the upper trachea. DAMGO (1 microM) inhibited the cholinergic response to EFS in a frequency-dependent manner in the main bronchi with greater inhibition at lower frequencies of stimulation.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
29.
Syntheses of several tripeptide analogues of leupeptin containing C-terminal argininal, lysinal, or ornithinal units are presented. The synthetic analogues were tested as inhibitors of trypsin, plasmin, and kallikrein. (Benzyloxycarbonyl)-L-leucyl-L-leucyl-L-argininal (2a) was significantly less effective as an inhibitor of trypsin and plasmin activity than leupeptin. (Benzyloxycarbonyl)-L-leucyl-L-leucyl-L-lysinal (2e) and (benzyloxycarbonyl)-L-leucyl-L-leucyl-L-ornithinal (2i) display different inhibition characteristics than (benzyloxycarbonyl)-L-leucyl-L-leucyl-L-argininal (2a). While (benzyloxycarbonyl)-L-leucyl-L-leucyl-L-argininal (2a) showed moderate inhibition of all three enzymes tested, (benzyloxycarbonyl)-L-leucyl-L-leucyl-L-lysinal (2e) was less effective as an inhibitor of trypsin and plasmin activity. Of the three enzymes tested, (benzyloxycarbonyl)-L-leucyl-L-leucyl-L-ornithinal (2i) showed significant inhibition of kallikrein activity only. Modifications made in the composition and sequence of the P2 and P3 amino acids also resulted in variations in the inhibitory activity of the analogues. In general, plasmin showed a strong preference for inhibitors which contain an L-phenylalanyl-L-leucyl or an L-leucyl-L-valyl unit in the P2 and P3 positions. 相似文献
30.
A case of obstructive sleep apnoea is reported that was caused by a dermoid cyst of the floor of the mouth and cured by surgery. 相似文献