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   1696210篇
  免费   123774篇
  国内免费   3784篇
耳鼻咽喉   21741篇
儿科学   55677篇
妇产科学   46174篇
基础医学   241347篇
口腔科学   48768篇
临床医学   151380篇
内科学   333668篇
皮肤病学   38676篇
神经病学   131200篇
特种医学   63938篇
外国民族医学   242篇
外科学   257326篇
综合类   38961篇
现状与发展   4篇
一般理论   531篇
预防医学   124281篇
眼科学   40239篇
药学   123706篇
  7篇
中国医学   4482篇
肿瘤学   101420篇
  2021年   12833篇
  2019年   13551篇
  2018年   19986篇
  2017年   15233篇
  2016年   16664篇
  2015年   18997篇
  2014年   26276篇
  2013年   38015篇
  2012年   52825篇
  2011年   55534篇
  2010年   32833篇
  2009年   30727篇
  2008年   51595篇
  2007年   54845篇
  2006年   55310篇
  2005年   52578篇
  2004年   50762篇
  2003年   48170篇
  2002年   46405篇
  2001年   91786篇
  2000年   93605篇
  1999年   76963篇
  1998年   19722篇
  1997年   17274篇
  1996年   17392篇
  1995年   16748篇
  1994年   15291篇
  1993年   14073篇
  1992年   57382篇
  1991年   55270篇
  1990年   52970篇
  1989年   50747篇
  1988年   46131篇
  1987年   44937篇
  1986年   42226篇
  1985年   39987篇
  1984年   29348篇
  1983年   24908篇
  1982年   13898篇
  1979年   25529篇
  1978年   17574篇
  1977年   14906篇
  1976年   13874篇
  1975年   14563篇
  1974年   17630篇
  1973年   16944篇
  1972年   15673篇
  1971年   14453篇
  1970年   13431篇
  1969年   12517篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
Conjugation pathways in liver disease.   总被引:2,自引:2,他引:0       下载免费PDF全文
1. The activities of microsomal glucuronyltransferase and thiomethyltransferase, and those of cytosolic sulphotransferase, acetyltransferase, glutathione transferase and thiomethyltransferase were measured in abnormal (cirrhosis and chronic hepatitis) and normal livers. 2. Glucuronyltransferase and sulphotransferase were investigated with 2-naphthol and ethinyloestradiol as substrates. p-Aminobenzoic acid, benzo(a)pyrene-4,5-epoxide and 2-mercaptoethanol were the substrates of acetyltransferase, glutathione transferase and thiomethyltransferase, respectively. 3. Enzyme activities are expressed as nmol min-1 incubation mg-1 protein and the averages (+/- s.d.) are given. With 2-naphthol as substrate, the glucuronyltransferase activity was 6.55 +/- 4.10 (abnormal liver, n = 33) and 7.81 +/- 4.02 (normal liver, n = 26) (NS); whereas sulphotransferase activity was 0.28 +/- 0.18 (abnormal liver, n = 35) and 0.68 +/- 0.43 (normal liver, n = 26) (P less than 0.01). Glucuronyltransferase activity towards ethinyloestradiol was 102.5 +/- 56.9 (abnormal liver, n = 30) and 107 +/- 59.9 (normal liver, n = 26) (NS), whereas sulphotransferase activity was 57.2 +/- 36.0 (abnormal liver, n = 35) and 122 +/- 67.6 (normal liver, n = 28) (P less than 0.01). Acetyltransferase activity was 0.84 +/- 0.83 (abnormal liver, n = 35) and 3.84 +/- 1.65 (normal liver, n = 26) (P less than 0.01). Glutathione transferase activity was 0.83 +/- 0.68 (abnormal liver, n = 35) and 2.90 +/- 1.59 (normal liver, n = 25) (P less than 0.01) and thiomethyltransferase activity was 1.00 +/- 0.69 (abnormal liver, n = 34) and 3.99 +/- 1.49 (normal liver, n = 25) (P less than 0.01). 4. Liver disease lowers the activities towards the substrates studied of sulphotransferase, acetyltransferase, glutathionetransferase and thiomethyltransferase but not that of glucuronyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
212.
The efficiency of Eurocollins or modified University of Wisconsin (UW) solution (MUW) in preserving rat livers was compared. After cold storage with one of the solutions, the livers were transplanted or perfused by collagenase for isolation of hepatocytes. Five of the 6 rats receiving a graft preserved with MUW versus none of the 6 rat receiving a graft preserved with Eurocollins solution survived 24 h or more. A significantly greater number of hepatocytes were isolated from livers preserved with MUW than from livers preserved with Eurocollins solution. This suggests a better reperfusion of MUW-preserved livers by collagenase resulting from less endothelial injury. LDH release by cultured hepatocytes, ketone body production and stimulation by glucagon were not significantly different between the two groups. These results confirm the superiority of MUW solution over Eurocollins in preserving liver grafts. They suggest that the advantage of MUW solution results from better protection of vascular endothelium rather than of hepatocytes.  相似文献   
213.
No excess of DR*3/4 in Ashkenazi Jewish or Hispanic IDDM patients   总被引:1,自引:0,他引:1  
The gene frequencies, haplotype relative risks, and zygotic assortments of HLA-DR in three ethnically defined samples of insulin-dependent diabetes mellitus (IDDM) patients were determined in a prospective family study. Although DR3 and DR4 were positively associated with IDDM in the probands of 123 northern European, 94 Ashkenazi Jewish, and 49 New York Hispanic families, significant excess of DR*3/4 heterozygotes was observed only among the probands from families of northern European ancestry. There was also a significant decrease in the frequency of Bw62,DR4 haplotypes derived by northern European patients from their mothers compared with their fathers. This difference, together with data reported in the literature, suggests that the expressivity of the susceptible genotype(s) in IDDM patients may be modified by protective maternal effects associated with Bw62,DR4 and probably other DR4 haplotypes. Samples of IDDM patients from populations with high frequencies of these modifiers should have different DR-gene frequencies contributed by fathers and mothers, capable of accounting for the observed Hardy-Weinberg disequilibrium. We postulate that, because the mechanism of action of these modifiers is distinct from that of the susceptibility gene, the difference must be considered in devising strategies for elucidation of the mode of inheritance of the disease and for understanding the molecular nature of the susceptibility.  相似文献   
214.
It has become common practice to rely on fitted estimates ofapparent in vivo metabolic constants (e.g., Vmax and KM) inparameterization of PBPK models. Yet, quantitative estimatesof precision in these fitted parameters are not routinely reported.Such information is needed to assess the reliability of modelpredictions. The purpose of this study was to assess the precisionin estimates of Vmax and KM for chloroform, accounting for boththe statistical uncertainties in parameter estimates from individualdata sets and any additional uncertainty due to differencesin the parameter estimates derived from various experiments.Joint confidence regions for Vmax and KM from each experiment,generated using maximum likelihood techniques, were used toevaluate these questions. Three previously published data setswere considered. Estimates of Vmax and KM obtained from thesedata sets differed more than could be explained as a consequenceof a limited number of observations, measurement error, or stochasticerror. Issues associated with the use of maximum likelihoodtechniques to estimate joint confidence regions, the estimationof metabolic constants from individual experiments within agas uptake study versus the full data set, the degree of overlapin the joint confidence regions for metabolic constants obtainedfrom separate data sets, and the implications for risk assessmentare discussed.  相似文献   
215.
Parker  Lisa S. 《JAMA》1998,280(20):1798-1799
  相似文献   
216.
We prospectively enrolled 160 consecutive patients with inversion trauma of the ankle in a diagnostic protocol that included physical examination within 2 days and at 5 days after trauma, arthrography, stress radiography, and ultrasonography. 135 patients had pathological lateral ligament laxity on the later physical examination or lateral ligament rupture diagnosed on arthrography and they were operated on. 122 of these patients had ligament ruptures.

At clinical follow-up after a minimum of half a year, all of the patients who were not operated on had stable joints without signs of previous ligament ruptures.

Delayed physical examination at 5 days after the injury led to the highest overall sensitivity (96%) and specificity (84%) for the detection of a ligament rupture. Additional diagnostic procedures, at a considerable cost, yielded little additional information.  相似文献   
217.
218.
In contrast with cross-sectional designs used in previous studies, this exploratory study compared survey data from 127 matched pairs of clinical pharmacists and physicians working together. Physicians' perceptions of the importance of clinical pharmacy activities for patient care and the competence of pharmacists performing the activities were examined for their influence on prescribing behavior in an institutional setting. Data from a national survey showed that physicians rated pharmacists higher regarding recommendations based on drug use evaluations (p = 0.004) and competency to provide all clinical pharmacy services. Scores for pharmacokinetics ratings were similar between pharmacists and physicians (p = 0.168). Pharmacists rated the importance of recommendations based on cost-effectiveness higher than physicians (p = 0.012). Overall, physicians' perceptions of activity importance for patient care and pharmacist competency appear to dictate pharmacists' influence on physician prescribing behavior (R = 0.723).  相似文献   
219.
Zusammenfassung Bei 205 Melanompatienten im Stadium I und II wurden das Ausma? der psychosozialen Belastung und der sozialen Unterstützung sowie die Einstellung der Patienten zu unterstützenden Gespr?chsangeboten erhoben. 59% der Patienten fanden zus?tzliche unterstützende Gespr?che mit dem behandelnden Dermatologen, 20% mit einem Psychotherapeuten sinnvoll. Patienten, die starke Angst vor einem Fortschreiten des Tumors ?u?erten und die sich über die Erkrankung nicht ausreichend aufgekl?rt fühlten, wünschten Gespr?che mit dem behandelnden Arzt. Patienten, die sich psychosozial st?rker belastet fühlten und sozial weniger Unterstützung durch ihr soziales Umfeld angaben, befürworteten Unterstützung durch einen Psychotherapeuten. Auch eine ungünstige Prognose scheint das Interesse an psychotherapeutischer Unterstützung zu verst?rken. Eingegangen am 13. Januar 1995 Angenommen am 23. August 1995  相似文献   
220.
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