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   95157篇
  免费   42193篇
  国内免费   475篇
耳鼻咽喉   1700篇
儿科学   4762篇
妇产科学   802篇
基础医学   17832篇
口腔科学   5407篇
临床医学   13929篇
内科学   26812篇
皮肤病学   7994篇
神经病学   14437篇
特种医学   2868篇
外国民族医学   2篇
外科学   16008篇
综合类   1263篇
一般理论   28篇
预防医学   5475篇
眼科学   1931篇
药学   6805篇
  6篇
中国医学   1383篇
肿瘤学   8381篇
  2024年   35篇
  2023年   201篇
  2022年   386篇
  2021年   1874篇
  2020年   5422篇
  2019年   11246篇
  2018年   10659篇
  2017年   11822篇
  2016年   12487篇
  2015年   12479篇
  2014年   12520篇
  2013年   13059篇
  2012年   5401篇
  2011年   5362篇
  2010年   9619篇
  2009年   5824篇
  2008年   2988篇
  2007年   1843篇
  2006年   1756篇
  2005年   1646篇
  2004年   1516篇
  2003年   1453篇
  2002年   1564篇
  2001年   1447篇
  2000年   1403篇
  1999年   824篇
  1998年   209篇
  1997年   166篇
  1996年   170篇
  1995年   153篇
  1994年   113篇
  1993年   87篇
  1992年   246篇
  1991年   224篇
  1990年   191篇
  1989年   212篇
  1988年   196篇
  1987年   155篇
  1986年   129篇
  1985年   107篇
  1984年   82篇
  1983年   75篇
  1982年   26篇
  1980年   26篇
  1979年   50篇
  1978年   24篇
  1977年   40篇
  1974年   26篇
  1973年   27篇
  1972年   25篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The objective of this study was to compare the clinical and laboratory consequences of left and right displacement of the abomasum (LDA and RDA), short‐ and long‐term survival after surgery and the findings in cows, that could not be cured by omentopexy. Data from 564 cases of displaced abomasum (466 LDA, 98 RDA) were analysed retrospectively. Clinical and laboratory findings were compared between the two manifestations of DA. Survival was assessed after 10 days and after 15 months. Necropsy was carried out on cows that died or were killed. On arrival at the clinic, left displacement of the abomasum (LDA) cows had been recognized as diseased for longer. LDA occurred earlier in lactation, and more cows with right displacement of the abomasum (RDA) were pregnant. Overall clinical symptoms were more severe in RDA than in LDA cows. Heart rate was higher, body temperature was lower, inanition, abnormal faeces and ruminal stasis were more frequent in RDA cows. Leucocyte counts were higher, and potassium and chloride levels were lower in RDA cows. Acetonuria was more frequent in LDA cows. More LDA than RDA cows were released from the clinic as cured (82.0% versus 74.5%). However, survival after the early post‐surgical period was similar for RDA and LDA cows. At necropsy, diseases of the gastrointestinal system were the predominant finding in RDA cows, while in LDA cows, diseases of the liver and other concurrent diseases were more important.  相似文献   
102.
103.
应用了A、B、C法7种单克隆抗体进行免疫组化染色,检测南京地区23例成人非何杰金淋巴瘤活检标本,结果示9例T系淋巴瘤,8例B系淋巴廇,非T非B及未定型淋巴瘤各3例。病理组织学表现与免疫表型符合率B系达80%,T系达60%。故根据形态学表现估测免疫表型是可行的。经HTLV抗体血清检测,仅1例多形细胞性T淋巴瘤患者阳性。  相似文献   
104.
105.
Objective: To determine the effects of a total laryngectomy on the swallow and subsequent quality of life in head and neck cancer patients. Design: Cross‐sectional single centre cohort study. Setting: Head and Neck Oncology Unit, Tertiary Referral Unit. Patients: Sixty‐two patients who underwent total laryngectomy at our centre participated in the study. Methods: Subjects were stratified by age, sex, tumour stage, other procedures such as myotomy and nerve re‐implantation. Pharyngectomy, glossectomy, flap reconstruction, neck dissection and previous radio‐ and chemotherapy were also assessed to see if they affected swallow and subsequent quality of life. Main outcome was measured using the MD Anderson Dysphagia Inventory questionnaire. Results: Responses were received from 46 males and 16 females (response rate of 80.5%) with a mean age of 64.7 years (SD 9.4). Median follow‐up in patients was 90 months (range 1–276). The mean MD Anderson Dysphagia Inventory total score in our series of patients was 77.7 (SD 16.6). MD Anderson Dysphagia Inventory global score was 79.4 (SD 22.6), Emotional score was 77.7 (SD 17.8), Functional score 81.3 (SD 15.9) and Physical score was 74.1(SD 18). Statistically significant differences were seen between the emotional scores of glossectomised and non‐glossectomised patients (Mann Whitney, P = 0.04). No significant correlation was seen between the subscale scores and the remaining treatment variables such as age, gender, site, tumour stage, myotomy, nerve implantation, radiotherapy, reconstruction and major complications. Conclusion: This questionnaire study is the largest of its type to assess the swallow of patients who have undergone laryngectomy at a single centre. The overall result confirmed that most patients had a subjectively good swallow. Only glossectomy and the method of PE segment closure were shown to significantly affect swallowing outcomes following surgery. We recommend further work especially prospective studies pre and post surgery using this or similarly validated instruments to fully assess swallow in the laryngectomy population.  相似文献   
106.
We have evaluated the in vitro effects of bromocriptine (Br), on the hepatic cytochrome P-450 monooxygenase system of rats pretreated with saline phenobarbitone (PB) and beta-naphthoflavone (BNF). Br inhibited ethoxyresorufin O-dealkylase (EROD) activity in liver microsomes of rats pretreated with saline and PB but not in BNF pretreated animals. Maximum inhibition of EROD activity by Br in the microsomes of saline and PB pretreated rats were 50%-60% of the control. In contrast, a dual effect was observed on aminopyrine N-demethylase activity (APD) by Br in microsomes of saline, PB and BNF pretreated rats. At a low concentration (25 microM), Br inhibited the activity of APD to a similar extent in all pretreatment groups; however, with higher concentrations of Br (50 microM to 300 microM), enhancement of APD activity was observed. Br (300 microM) increased the APD activity to 2-3 times the control level in microsomes of rats pretreated with saline, PB or BNF. Spectral studies revealed a Type II binding of Br to cytochrome P-450 from microsomes of saline and PB pretreated rats. A reverse type I binding was observed for BNF induced microsomes. In addition, Br also enhanced NADPH cytochrome c (P-450) reductase activity to a similar extent in all pretreatment groups. These results suggest that the inhibition of EROD activity may be due to direct binding by Br to certain isozymes of cytochrome P-450 and that the enhancing effect of Br on APD activity may be in part due to the activation of the NADPH cytochrome c reductase component of the cytochrome P-450 monooxygenase system.  相似文献   
107.
Alopecia areata is an inflammatory hair loss disease with a major genetic component. The presence of focal inflammatory lesions with perifollicular T‐cell infiltrates reflects the importance of local cytokine production in the pathogenesis. In addition to its fundamental pro‐inflammatory role, the interleukin‐1 (IL‐1) system has major effects on hair growth regulation in vitro, with the inhibitory actions of IL‐1α and IL‐1β being opposed by the receptor antagonist IL‐1ra. The novel interleukin‐1 like molecule 1 (IL‐1L1) which has greatest gene sequence homology with IL1RN, the gene encoding IL‐1ra, is another potential IL‐1 antagonist. In view of previous studies suggesting a significant role for IL1RN polymorphisms in the pathogenesis of autoimmune/inflammatory disease, we have analysed polymorphisms of IL‐1ra (IL1RN+2018) and its homologue IL‐1L1 (IL1L1+4734) in a case–control association study on 165 patients and a large number of matched controls. Homozygosity for the rare allele of IL1RN (IL1RN*2) was significantly associated with alopecia areata [odds ratio (OR) = 1.89, 95% CI (1.09, 3.28); P = 0.02], confirming our previous findings of significant association with the IL1RN variable number tandem repeat (VNTR). The results also revealed a novel association involving a polymorphism of the interleukin‐1 receptor antagonist homologue IL1L1 at position + 4734, IL1RN+2018, and alopecia areata. The effect of a genotype combining three copies of the rare alleles at the IL1RN and IL1L1 loci conferred a more than additive increase in the risk of disease compared to IL1RN+2018 or IL1L1+4734 alone [OR 3.37 (1.60, 7.06); P = 0.002], suggesting possible synergy between the IL1RN and IL1L1 genes. This effect was stronger in patients with severe disease (alopecia totalis/universalis) [OR 4.62 (1.87, 11.40), P = 0.0022], and in those with early age at onset (< 20 years) [OR = 6.38 (2.64, 15.42), P = 0.0002]. Our results suggest that these polymorphisms within IL1RN and IL1L1 themselves or a gene in linkage disequilibrium with IL1RN and IL1L1 predispose to the more severe forms of alopecia areata.  相似文献   
108.
Alzheimer's disease is one of the main causes of senile dementia. Although its pathogenesis is not clear, some evidence has revealed that the activity of acetylcholine receptor in the brains of these patients is decreased. In the present study, possible circulating factors, affecting the muscarinic acetylcholine receptor of the synaptic vesicle from the rat brain, were evaluated in the serum of 95 senile subjects (34 males and 61 females, mean +/- SD age of 77.5 +/- 8.6 years). The cognitive function of these subjects was assessed by their Mini-Mental State scores, and they subjects were divided into non-dementic-subjects with a score of 21 or more, or subjects with dementia with a score of 20 or less. The latter were further divided into senile dementia with Alzheimer type (SDAT) and vascular type dementia (VS) using Hatchinski's ischemic score. The mean suppression rate by the serum from the SDAT patients on the binding of tritiated quinuclidinyl benzilate (3H-QNB), an antagonist for muscarinic acetylcholine receptor, to the rat synaptic membrane, was 18.1 +/- 7.2% of the control value, which was significantly greater than that of the non-dementic subjects, (4.7 +/- 3.8%). However, that in the VD group (8.4 +/- 6.8%), was not significantly different from the control value. Moreover the suppression rate of the serum on 3H-QNB binding showed significant positive correlated with score for the Mini-Mental State (r = 0.480, p less than 0.01) in the SDAT group. These data support the hypothesis that circulating suppression factors may participate in the pathogenesis of SDAT.  相似文献   
109.
110.
Background: Scleromyxoedema is a rare disease of unknown aetiology that is characterized by deposition of mucin and sclerotic induration of the skin; it is associated with paraproteinaemia. Patients suffer from progressive disability due to immobilization and cosmetic disfigurement. Treatment of scleromyxoedema is a therapeutic challenge. The antimalarial hydroxychloroquine has a rapid and reliable effect in reticular erythematous mucinosis. Patients and methods: Four consecutive patients (two women, two men; median age: 50 years) with scleromyxoedema, three of them with IgG λ paraprotein, were treated with hydroxychloroquine. Treatment was initiated with 600 mg p. o. for 10 days, followed by 400 mg for at least 4 weeks, and 200 mg thereafter. Results: Complete remission of skin manifestations was achieved in one patient, whereas three patients achieved a partial remission of 61+, 5 and 25 months' duration. Notably, three patients felt increased mobility and reduced firmness of skin during the first week of treatment, which was reflected in a rapid reduction in dermal thickness. In one patient, dysphagia was reverted as evidenced by normalization of oesophageal clearance. Paraproteinaemia was not influenced at all. Side effects included one case of electroretinogram abnormalities after 19 months of therapy and one case of leucopenia after 3 months. Conclusion: Hydroxychloroquine is an effective form of therapy for scleromyxoedema, leading to rapid and prolonged alleviation of symptoms.  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