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   16147篇
  免费   1165篇
  国内免费   37篇
耳鼻咽喉   160篇
儿科学   697篇
妇产科学   540篇
基础医学   2148篇
口腔科学   513篇
临床医学   1904篇
内科学   3030篇
皮肤病学   322篇
神经病学   1409篇
特种医学   425篇
外国民族医学   1篇
外科学   1539篇
综合类   224篇
一般理论   24篇
预防医学   1755篇
眼科学   391篇
药学   1150篇
中国医学   26篇
肿瘤学   1091篇
  2023年   120篇
  2022年   177篇
  2021年   405篇
  2020年   261篇
  2019年   394篇
  2018年   398篇
  2017年   334篇
  2016年   372篇
  2015年   398篇
  2014年   539篇
  2013年   749篇
  2012年   1094篇
  2011年   1162篇
  2010年   670篇
  2009年   600篇
  2008年   949篇
  2007年   1078篇
  2006年   929篇
  2005年   902篇
  2004年   830篇
  2003年   819篇
  2002年   759篇
  2001年   212篇
  2000年   195篇
  1999年   236篇
  1998年   149篇
  1997年   111篇
  1996年   106篇
  1995年   110篇
  1994年   104篇
  1993年   83篇
  1992年   121篇
  1991年   122篇
  1990年   107篇
  1989年   122篇
  1988年   115篇
  1987年   123篇
  1986年   111篇
  1985年   131篇
  1984年   78篇
  1983年   78篇
  1982年   82篇
  1981年   54篇
  1979年   77篇
  1978年   81篇
  1977年   64篇
  1976年   58篇
  1975年   54篇
  1974年   48篇
  1973年   49篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Nephrotic syndrome (NS) represents the association of proteinuria, hypoalbuminemia, edema, and hyperlipidemia. Steroid-resistant NS (SRNS) is defined by primary resistance to standard steroid therapy. It remains one of the most intractable causes of ESRD in the first two decades of life. Mutations in the NPHS2 gene represent a frequent cause of SRNS, occurring in approximately 20 to 30% of sporadic cases of SRNS. On the basis of a very small number of patients, it was suspected that children with homozygous or compound heterozygous mutations in NPHS2 might exhibit primary steroid resistance and a decreased risk of FSGS recurrence after kidney transplantation. To test this hypothesis, NPHS2 mutational analysis was performed with direct sequencing for 190 patients with SRNS from 165 different families and, as a control sample, 124 patients with steroid-sensitive NS from 120 families. Homozygous or compound heterozygous mutations in NPHS2 were detected for 43 of 165 SRNS families (26%). Conversely, no homozygous or compound heterozygous mutations in NPHS2 were observed for the 120 steroid-sensitive NS families. Recurrence of FSGS in a renal transplant was noted for seven of 20 patients with SRNS (35%) without NPHS2 mutations, whereas it occurred for only two of 24 patients with SRNS (8%) with homozygous or compound heterozygous mutations in NPHS2. None of 29 patients with homozygous or compound heterozygous mutations in NPHS2 who were treated with cyclosporine A or cyclophosphamide demonstrated complete remission of NS. It was concluded that patients with SRNS with homozygous or compound heterozygous mutations in NPHS2 do not respond to standard steroid treatment and have a reduced risk for recurrence of FSGS in a renal transplant. Because these findings might affect the treatment plan for childhood SRNS, it might be advisable to perform mutational analysis of NPHS2, if the patient consents, in parallel with the start of the first course of standard steroid therapy.  相似文献   
992.
OBJECTIVE: We tested the hypothesis that altering the pre-exercise muscle temperature would influence the magnitude of muscle damage induced by eccentric exercise. SUBJECTS: Female students who had no experience in resistance training were placed into either a microwave treatment group (n = 10) or an icing treatment group (n = 10). DESIGN AND SETTING: Subjects in each group performed 12 maximal eccentric actions of the forearm flexors of each arm on 2 separate occasions separated by 4 weeks. Before testing, the exercise arm was subjected to either passive warming (microwave) or control for the microwave treatment group or cooling (icing) or control for the icing treatment group. The control arm performed the same exercise protocol without treatment. Limbs were randomized for treatment or control and order of testing. Deep muscle temperature increased by approximately 3 degrees C after the microwave treatment and decreased approximately 5 degrees C after the icing treatment. MEASUREMENTS: We evaluated changes in maximal isometric force and indirect markers of muscle damage, including range of motion, upper arm circumference, muscle soreness, and plasma creatine kinase activity, in the microwave and control and icing and control groups using a 2-way, repeated-measures analysis of variance. RESULTS: All measures changed significantly (P <.01) after exercise, but neither of the treatments demonstrated significant effects on most of the variables compared with the control. CONCLUSIONS: These results suggest that pre-exercise cooling does not affect the magnitude of muscle damage in response to eccentric exercise. Similarly, pre-exercise passive muscle warming did not prove beneficial in attenuating indicators of muscle damage. Thus, any beneficial effects of warm-up exercise cannot be attributed to the effects of increased muscle temperature.  相似文献   
993.
This article examines the impact of the introduction of ICD-10 on mortality from circulatory diseases in England and Wales. The article examines changes to specific types of circulatory disease, focussing on ischaemic heart disease (IHD) and cerebrovascular disease (stroke). The main changes are highlighted and the article explains how data can be adjusted to take account of these changes so that trends over time can be analysed. The article then looks at the impact of the changes on baselines for Government targets to reduce mortality from circulatory diseases. The number of deaths assigned to circulatory diseases increases by 3-4 per cent as a result of the introduction of ICD-10, replacing ICD-9. For cerebrovascular diseases specifically, the increase is 9 per cent for females and 13 per cent for males. Trends in mortality from IHD are unaffected by the introduction of ICD-10. However, the number of deaths assigned to acute myocardial infarction, which forms part of IHD, decreases by around 10 per cent when ICD-10 is used instead of ICD-9.  相似文献   
994.
Partial DiGeorge syndrome (pDGS) is an inherited primary immunodeficiency syndrome (incidence, 1:3000 live births) primarily affecting cellular immune function; partial, infers thymic hypoplasia with detectable circulating T-lymphocytes and adequate function. No guidelines exist regarding the recommendations for use of live viral vaccines (LVVs) in this extensive population of pediatric patients. We reviewed the experience with live viral vaccines in our cohort of patients with pDGS. Of 53 patients, 25 (47%) had received a live viral vaccine. No significant adverse events were recorded in association with administration of live viral vaccines. There was no statistically significant difference between cellular immune function at initial presentation between those patients that received live viral vaccines and those that did not. Adequate cellular immune function was documented for 15 of the 25 LVV recipients at the time of vaccine administration without significant change from baseline. These observations suggest that live viral vaccines appear safe in patients with pDGS and stable immune function.  相似文献   
995.
BACKGROUND: Leaving the hospital against medical advice has been associated with increased morbidity and readmission. Factors associated with the risk of leaving against medical advice among HIV/AIDS patients or injection drug users have not been examined in detail. OBJECTIVES: To examine the clinical and social factors associated with leaving against medical advice (AMA) from a specialized HIV/AIDS ward among patients who reported a history of injection drug use. METHODS: All patients with a history of injection drug use admitted to the HIV/AIDS ward at St. Paul's Hospital, Vancouver, British Columbia (the largest specialized HIV/AIDS hospital ward in Canada) between April 1997 and October 2000 were reviewed retrospectively. A multivariate logistic regression model utilizing a generalized estimating equation algorithm identified factors associated with leaving the hospital AMA. RESULTS: Of the 1056 hospital admissions to the HIV/AIDS ward by patients with a history of injection drug use, 263 (24.9%) resulted in leaving the hospital AMA. Independent positive predictors of leaving AMA included recent injection drug use (adjusted odds ratio [AOR] = 2.08, 95% confidence interval [CI]: 1.41-3.07) and aboriginal ethnicity (AOR = 1.55, 95% CI: 1.05-2.28). Discharge AMA was also more likely to occur on weekends (AOR = 2.27, 95% CI: 1.49-3.48) and on days when social assistance payments were issued (AOR = 2.95, 95% CI: 1.70-5.10). Factors that independently reduced the odds of hospital discharge AMA included in-hospital methadone use (AOR = 0.49, 95% CI: 0.32-0.76), social support (AOR = 0.33, 95% CI: 0.21-0.51), and older age (per 10-year increment, AOR = 0.56, 95% CI: 0.43-0.73). CONCLUSIONS: Among HIV-positive patients with a history of injection drug use, the odds of leaving the hospital AMA were reduced for subjects who received inpatient methadone treatment, were of older age, or had social supports. Addiction treatment and interventions that enhance social supports in marginalized populations at risk for hospital discharge AMA should be further explored.  相似文献   
996.
A 46,XYq 8-year-old male was referred for microcephaly, growth, and mental retardation, hypotonia, genital hypoplasia, and dysmorphisms. FISH analysis showed that the rearranged Y chromosome originated from an unbalanced translocation of Xq27.3-qter onto the deleted Yq11.22. Analysis of reported patients with disomy of region distal to Xq26 suggests that this rare anomaly, associated with failure to dosage compensate X-linked genes that are normally inactivated, when present in two copies, is causing a quite distinct phenotype. This imbalance is the aberrant by product of the recombinogenic pairing of the distal pseudoautosomal Xq-Yq region at male meiosis.  相似文献   
997.
998.
Benign reparative lesions in the head and neck region in infants are rare and often difficult to classify on histology. Discussed herein are two rare lesions in infants occurring at identical locations in the nasal cavity with striking histologic similarity but different histologic labels. One was a case of nasal chondromesenchymal hamartoma (NCMH) occurring in a 1-year-old child and the other an aneurysmal bone cyst (ABC) like lesion affecting a 4-month infant. Both these lesions were locally destructive and had nearly similar clinical presentation. Both on immunohistochemistry showed myofibroblastic nature and had similar histology except that the ABC like lesion lacked the cartilage component of the former. In view of great similarity in the two lesions, it was thought that the second lesion might also represent a reparative, non-cartilage-containing counterpart of the former.  相似文献   
999.
BACKGROUND: Women with breast cancer are at risk of developing lymphedema following surgical and/or medical treatment of the disease. Recently, women have challenged traditional advice about limiting upper extremity activity to prevent lymphedema by participation in dragon boat racing. PURPOSE: In this qualitative pilot study, three women were interviewed about the meaningfulness of dragon boat racing in their lives. METHODS: The women were interviewed twice and their interviews analyzed using thematic analysis. RESULTS: Seven themes are discussed: attraction of dragon boat racing; physical and emotional well-being; competition; social support; transcendence/connectedness/oneness; re-occurrence of cancer; and, public awareness. Competition enabled the participants to rebuild self-confidence and to regain control over their physical health and emotional well-being. Balancing support and competition was key to finding satisfaction in this occupation. The women did not believe that dragon boat racing affected their risk for developing lymphedema. PRACTICE IMPLICATIONS: People who engage in the occupation of dragon boat racing find it meaningful and develop new coping strategies. Participating in dragon boat racing can decrease stress and shift the meaning of having breast cancer to a more positive view of the experience.  相似文献   
1000.
BACKGROUND: Isotretinoin is a known teratogen, and when it is prescribed to women of childbearing potential, 2 forms of contraception must be used, commonly including hormonal contraception. Although isotretinoin and estradiol are metabolized largely by cytochrome P450 (CYP) 3A4 and glucuronidation, the potential for clinical drug interaction, with subsequent pharmacodynamic impact, has not been evaluated. METHODS: We enrolled 26 healthy women who were to receive isotretinoin for the treatment of severe, recalcitrant nodular acne and who were taking or planning to take oral contraceptives. The pharmacokinetics of ethinyl estradiol and norethindrone (INN, norethisterone) (the components of Ortho Novum 7/7/7; Ortho-McNeil Pharmaceutical, Inc, Raritan, NJ) and pharmacodynamic assessments of oral contraceptive effectiveness (concentrations of serum progesterone, luteinizing hormone, and follicle-stimulating hormone) were determined on days 6 and 20 of 2 separate oral contraceptive cycles, before and during isotretinoin treatment. RESULTS: The addition of isotretinoin to the oral contraceptive regimen resulted in small and inconsistent, although statistically significant (P <.04), decreases in the concentrations of both ethinyl estradiol (9% decrease in area under the plasma concentration-time curve from time 0 to 24 hours after the dose on day 6) and norethindrone (11% decrease in maximum plasma concentration on day 20). Isotretinoin did not cause any statistically significant increases in pharmacodynamic markers, although a majority of women had increases in these measures. Although there was no correlation between isotretinoin (or metabolite) levels and oral contraceptive levels (P >.05), there was a correlation between progesterone level and oral contraceptive levels (P <.05). Variability was large for both pharmacokinetic measures (median coefficients of variation of 44%-69% [for each time point within a study period]) and pharmacodynamic measures (median coefficients of variation of 64%-114%). One woman in each study phase, one before and one during isotretinoin treatment, had a progesterone elevation consistent with possible ovulation. No serious or unexpected adverse events were observed. CONCLUSIONS: The small reduction in ethinyl estradiol and norethindrone levels associated with isotretinoin was not associated with any pharmacodynamic changes in our study. The combination of the teratogenic risk of isotretinoin and the large variability of and correlation between oral contraceptive levels and pharmacodynamic measures, however, strongly reinforces the necessity of additional contraceptive methods during concomitant administration of these drugs.  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