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   76272篇
  免费   6678篇
  国内免费   4210篇
耳鼻咽喉   773篇
儿科学   1145篇
妇产科学   1101篇
基础医学   8469篇
口腔科学   1163篇
临床医学   9446篇
内科学   11296篇
皮肤病学   1047篇
神经病学   4564篇
特种医学   2770篇
外国民族医学   36篇
外科学   8222篇
综合类   10903篇
现状与发展   13篇
一般理论   10篇
预防医学   6101篇
眼科学   2045篇
药学   7382篇
  54篇
中国医学   4159篇
肿瘤学   6461篇
  2024年   276篇
  2023年   1088篇
  2022年   2664篇
  2021年   3621篇
  2020年   2859篇
  2019年   2449篇
  2018年   2763篇
  2017年   2502篇
  2016年   2398篇
  2015年   3545篇
  2014年   4433篇
  2013年   4433篇
  2012年   6464篇
  2011年   6774篇
  2010年   4398篇
  2009年   3663篇
  2008年   4532篇
  2007年   4291篇
  2006年   4064篇
  2005年   3752篇
  2004年   2654篇
  2003年   2483篇
  2002年   2151篇
  2001年   1271篇
  2000年   1160篇
  1999年   1128篇
  1998年   761篇
  1997年   688篇
  1996年   545篇
  1995年   505篇
  1994年   393篇
  1993年   315篇
  1992年   353篇
  1991年   331篇
  1990年   231篇
  1989年   182篇
  1988年   191篇
  1987年   162篇
  1986年   119篇
  1985年   96篇
  1984年   78篇
  1983年   48篇
  1982年   52篇
  1981年   43篇
  1980年   33篇
  1979年   46篇
  1978年   23篇
  1977年   20篇
  1973年   18篇
  1972年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Summary To investigate the distribution of possible novel mutations from parkin gene in variant subset of patients with Parkinson’s disease (PD) in China and explore whether parkin gene plays an important role in the pathogenesis of PD, 70 patients were divided into early-onset group and late-onset group; 70 healthy subjects were included as controls. Genomic DNA from 70 normal controls and from those of PD patients were extracted from peripheral blood leukocytes by using standard procedures. Mutations of parkin gene (exon 1–12) in all the subjects were screened by PCR-single strand conformation polymorphism (SSCP), and further sequencing was performed in the samples with abnormal SSCP results, in order to confirm the mutation and its location. A new missense mutation Gly284Arg in a patient and 3 abnormal bands in SSCP electrophoresis from samples of another 3 patients were found. All the DNA variants were sourced from the samples of the patients with early-onset PD. It was concluded that Parkin point mutation also partially contributes to the development of early-onset Parkinson’s disease in Chinese. WANG Tao, male, born in 1961, Associate Professor This work was supported by grants from the key program of the special scientific project of Scientific & Technologic Agency of Hubei Province (Serial No. 2001AA308B01) and the Hygienic Research Project of Hygienic Agency of Hubei province (Serial No. WJ 01529).  相似文献   
22.
The Physical Capacity Evaluation, a performance measure of functional capabilities comprised of 13 tasks simulating those used in activities of daily living, was tested on 289 community-dwelling elderly people and compared against a widely used self-report measure of function, the Health Assessment Questionnaire. Factor analysis identified one dominant component in each instrument. Internal consistency reliability (Cronbach's alpha) was .90 for both instruments. Global disability (Health Assessment Questionnaire) and function (Physical Capacity Evaluation) scores were correlated -.74. One-week retest reliabilities on 58 subjects were .94 for the Physical Capacity Evaluation and .95 for the Health Assessment Questionnaire. The Physical Capacity Evaluation is a valid and reliable measure of physical performance for use with elderly people.  相似文献   
23.
目的:了解流通领域中阿莫西林制剂的质量状况。方法:在全省各市县的部分医药经营企业,抽取阿莫西林胶囊及干糖浆共54批样品,按国家药品标准进行全检后,对其检验结果进行统计分析。结果:不合格的项目有含量、胶囊剂溶出度、干糖浆粒度。该药物制剂的标示百分含量普遍偏低。结论:影响该产品质量的主要项目是含量和溶出度,含量偏低的主要原因是厂家的低限投料,应予以充分重视。  相似文献   
24.
BACKGROUND: Chronic renal failure (CRF) is associated with an atherogenic lipid profile and an increased risk of ischaemic cardiovascular disease. The associated hyperlipidaemia is reportedly ameliorated by erythropoietin (Epo) therapy. According to a recent report, rats studied 3 weeks after 5/6 nephrectomy and fed a high- protein diet exhibited increased activities of hepatic HMG-CoA reductase (HMG-CoAR) and cholesterol 7 alpha-hydroxylase (Ch-7 alpha- H), despite normal corresponding mRNA values. DESIGN AND METHODS: This study was designed to examine the effects of naturally progressing CRF of longer duration as well as those of Epo therapy on gene expressions of the key factors involved in hepatic cholesterol metabolism, i.e., LDL receptor (LDLR), HMG-CoAR, and Ch-7 alpha-H. Sprague-Dawley rats were randomized to the CRF group (5/6 nephrectomy), Epo-treated CRF group (given Epo 150 U/kg/twice weekly) and sham-operated, placebo- treated normal controls. They were allowed free access to regular rat chow and studied 6 weeks after surgery. Liver mRNAs and protein mass or activities of the above factors were studied. RESULTS: Plasma cholesterol concentration was significantly increased in the CRF group (P < 0.001) and was modestly lowered (P < 0.05) by Epo therapy. However, microsomal cholesterol concentration and LDLR, HMG-CoAR, and Ch-7 alpha-H mRNA as well as HMG-CoAR activity, and Ch-7 alpha-H and LDLR protein mass measurements were virtually identical in the three groups. Thus, hepatic LDLR, HMG-CoAR, and Ch-7 alpha-H mRNA and protein measurements in rats with CRF were similar to those of the normal control group representing an inappropriate response to the associated hypercholesterolemia. Epo therapy led to partial amelioration of CRF- associated hypercholesterolaemia with no discernible effect on hepatic tissue expression of the above factors.   相似文献   
25.
Background: For local anesthetics, the process of removal from the site of administration influences the duration of anesthesia and the risk for systemic toxicity to develop. The systemic absorption of epidural ropivacaine and the time profile of sensory and motor block were studied in healthy volunteers.

Methods: Nine persons simultaneously received 150 mg ropivacaine hydrochloride (7.5 mg/ml) epidurally and 40 mg deuterium-labeled (sup 2 H sub 3)ropivacaine hydrochloride (0.25 mg/ml) intravenously. Peripheral arterial and venous plasma samples were collected, and assessments of sensory and motor block were made.

Results: The arterial plasma concentrations increased faster than the venous concentrations, with 50% higher maximum concentrations after both intravenous and epidural administration. The absorption was biphasic. A correlation was seen between the duration of sensory block and the slower absorption half-life; that is, the longer the half-life, the longer the duration. The extent of spread varied among the volunteers, with the median upper block level not exceeding T12. The motor block (Bromage score 1) was of slower onset (median, 0.4 h) and of shorter duration (median, 4.1 h) than the sensory block (onset, 0.2 h; duration, 6.5 h at L2 medians).  相似文献   

26.
Open reduction combined with external compressive skeletal fixation was used to treat twenty-seven patients who had a separated fracture of the patella. Fixation was obtained by the use of two compressive clamps applied to stainless-steel pins that were inserted just proximal and distal to the proximal and distal poles of the patella. Range-of-motion exercises for the knee were begun at two weeks and the pins were removed at three to four weeks. All of the fractures healed. Twenty-four patients regained a range of motion that was equal to that of the opposite knee. There was no evidence of chronic osteomyelitis. Osteoarthritis was noted in one patient who refused excision of a portion of the patella.  相似文献   
27.
28.
It has been suggested that gains of chromosomes 7 and 17 and loss of Y occur in renal papillary adenoma and that progression to papillary renal cell carcinoma is marked by gains of additional chromosomes, most frequently 12, 16, and 20. Previous studies have included very few lesions of <5 mm in diameter, a requirement of the present definition of papillary adenoma. Ten papillary adenomas (ranging from 1 to 5 mm in diameter) from autopsy material and 10 surgically resected papillary renal cell carcinomas were studied with fluorescence in situ hybridization in paraffin sections using centromeric probes for chromosomes 7, 12, 16, 17, 20, and Y diluted 1:100 with tDenHyb1 buffer. The signals in 50 to 150 nuclei were counted in each tumor. Controls for all the probes were normal renal tissues from the same patients. Three or more signals per nucleus were frequently observed in papillary adenomas: chromosome 7 (range, 10 to 50%; > or = 30% in 9 of 10), 17 (range, 10 to 47%; > or = 30% in 7), 16 (range, 1 to 63%; > or = 10% in 5), 12 (range, 0 to 32%; > or =10% in 4), and 20 (range, 5 to 49%; > or = 10% in 5). Loss of the Y chromosome was observed in 80 to 90% of nuclei in 9 adenomas from males. Three or more signals were frequent in papillary renal cell carcinomas: chromosome 7 (range, 32 to 63%; > or =30% in 10 of 10), 17 (range, 28 to 61%; > or = 30% in 7), 16 (range, 0 to 45%; > or = 10% in 6), 12 (range, 1 to 37, > or = 10% in 5), 20 (range, 2 to 44%; > or = 10% in 4). No signal for Y was observed in 12 to 88% (> or = 81% in 6) of nuclei in 7 carcinomas from males. Statistical analysis showed no difference between adenomas and carcinomas. Gains of chromosomes 7, 17, 16, 12, and 20 and loss of the Y chromosome occur early in the evolution of papillary renal cell neoplasia in tumors that are only a few millimeters in diameter. Progressive gains of these chromosomes do not appear to correlate with the transition from adenoma to carcinoma.  相似文献   
29.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired chronic hemolytic anemia associated with an unusual susceptibility to hemolytic crisis, infection, and venous thrombosis which would be aggravated by a number of factors including surgery. We report a case of PNH undergoing percutaneous transluminal coronary angioplasty and discuss the corresponding perioperative management.  相似文献   
30.
Twenty-seven in-patients with obstetric DIC in our hospital from Jan. 1971 to Dec. 1990 were analysed retrospectively. The incidence was 0.12% in the first decade and 0.02%, in the second, showing a difference of significance between them. The most common predisposing factors included amniotic fluid embolism, abruptio placenta and hemorrhagic shock. Bleeding from multi-organs in various extent and coagulation disorders occurred in all those 27 cases. [Besides anti-shock treatment, heparin was employed together with fibrinogen in 4 postpartum and 1 antepartum DIC patients, fibrinogen alone in 8 cases, and hysterectomy in 11 cases. 17 patients were saved and 9 died. It is important that early diagnosis and much attention paid to clinical characteristics together with serial laboratory tests. Key management should include prompt treatment and eradication of predisposing factors. Quick decision spite of to terminate the pregnancy and even hysterectomy should be done in some risks.  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