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   9189篇
  免费   866篇
  国内免费   73篇
耳鼻咽喉   113篇
儿科学   254篇
妇产科学   451篇
基础医学   1117篇
口腔科学   213篇
临床医学   1021篇
内科学   2074篇
皮肤病学   124篇
神经病学   602篇
特种医学   242篇
外科学   1475篇
综合类   211篇
现状与发展   1篇
一般理论   1篇
预防医学   455篇
眼科学   161篇
药学   694篇
中国医学   86篇
肿瘤学   833篇
  2023年   65篇
  2022年   136篇
  2021年   293篇
  2020年   164篇
  2019年   321篇
  2018年   354篇
  2017年   268篇
  2016年   276篇
  2015年   337篇
  2014年   434篇
  2013年   494篇
  2012年   677篇
  2011年   723篇
  2010年   445篇
  2009年   404篇
  2008年   551篇
  2007年   516篇
  2006年   488篇
  2005年   478篇
  2004年   428篇
  2003年   368篇
  2002年   373篇
  2001年   235篇
  2000年   214篇
  1999年   170篇
  1998年   51篇
  1997年   59篇
  1996年   43篇
  1995年   38篇
  1994年   36篇
  1993年   20篇
  1992年   88篇
  1991年   71篇
  1990年   70篇
  1989年   58篇
  1988年   49篇
  1987年   28篇
  1986年   32篇
  1985年   41篇
  1984年   28篇
  1983年   22篇
  1982年   13篇
  1981年   22篇
  1979年   17篇
  1978年   10篇
  1977年   14篇
  1976年   12篇
  1975年   13篇
  1973年   13篇
  1972年   12篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
An 8-year-old male with a complex developmental syndrome and severe obesity was heterozygous for a de novo missense mutation resulting in a Y722C substitution in the neurotrophin receptor TrkB. This mutation markedly impaired receptor autophosphorylation and signaling to MAP kinase. Mutation of NTRK2, which encodes TrkB, seems to result in a unique human syndrome of hyperphagic obesity. The associated impairment in memory, learning and nociception seen in the proband reflects the crucial role of TrkB in the human nervous system.  相似文献   
72.

Objectives

Automated point-of-care molecular assays have greatly shortened the turnaround time of respiratory virus testing. One of the major bottlenecks now lies at the specimen collection step, especially in a busy clinical setting. Saliva is a convenient specimen type that can be provided easily by adult patients. This study assessed the diagnostic validity, specimen collection time and cost associated with the use of saliva.

Methods

This was a prospective diagnostic validity study comparing the detection rate of respiratory viruses between saliva and nasopharyngeal aspirate (NPA) among adult hospitalized patients using Xpert® Xpress Flu/RSV. The cost and time associated with the collection of saliva and nasopharyngeal specimens were also estimated.

Results

Between July and October 2017, 214 patients were recruited. The overall agreement between saliva and NPA was 93.3% (196/210, κ 0.851, 95% CI 0.776–0.926). There was no significant difference in the detection rate of respiratory viruses between saliva and NPA (32.9% (69/210) versus 35.7% (75/210); p 0.146). The overall sensitivity and specificity were 90.8% (81.9%–96.2%) and 100% (97.3%–100%), respectively, for saliva, and were 96.1% (88.9%–99.2%) and 98.5% (94.7%–99.8%), respectively, for NPA. The time and cost associated with the collection of saliva were 2.26-fold and 2.59-fold lower, respectively, than those of NPA.

Conclusions

Saliva specimens have high sensitivity and specificity in the detection of respiratory viruses by an automated multiplex Clinical Laboratory Improvement Amendments-waived point-of-care molecular assay when compared with those of NPA. The use of saliva also reduces the time and cost associated with specimen collection.  相似文献   
73.
BACKGROUND: Impaired implantation in assisted reproduction cycles with high serum estradiol (E(2)) concentrations may be related to suboptimal endometrial perfusion. Endometrial and subendometrial blood flow were compared between excessive responders (serum E(2) on the day of HCG >20 000 pmol/l) and moderate responders (E(2) < or =20 000 pmol/l). METHODS: Three-dimensional (3D) ultrasound examination with power Doppler was performed 2, 4 and 7 days after HCG in 32 patients who did not have embryo transfer in order to measure endometrial thickness, pulsatility index (PI)/resistance index (RI) of uterine vessels, and endometrial volume, vascularization index (VI)/flow index (FI)/vascularization flow index (VFI) of endometrial and subendometrial regions. RESULTS: Excessive responders tended to have lower endometrial and subendometrial VI/VFI on HCG +2 and more absent endometrial/subendometrial blood flow. They had significantly higher endometrial FI and subendometrial VFI than moderate responders on HCG +7. Only in the excessive responder group, uterine PI/RI declined significantly from HCG +2 to HCG +7 and endometrial VI/VFI increased significantly from HCG +4 to HCG +7. CONCLUSION: Changes in uterine Doppler flow indices, and endometrial and subendometrial 3D power Doppler flow indices during the early luteal phase were significantly different between moderate and excessive responders.  相似文献   
74.
Neonatal sepsis is a major cause of death in newborns despite sophisticated neonatal intensive care. This retrospective study reviewed the clinical characteristics of cases of culture-proven sepsis in a neonatal intensive care unit from January 1992 to December 2001. Patients were divided into those with onset of sepsis in the first 7 days of life (early-onset group) and those with onset after the seventh day of life (late-onset group). A total of 270 cases with 325 episodes of sepsis and 353 isolated pathogens were identified and included in the study. The male-to-female ratio was 1.4. The majority of cases of sepsis occurred in low birth weight (75.9%) and premature babies (76.7%). Late onset occurred in 71.9% of cases. Patients with late onset had a lower mortality rate than those with early onset (11.3% vs 28.9%). Coagulase-negative staphylococci (20.1%) was the most common organism isolated, but infection with Pseudomonas aeruginosa was associated with the highest morality rate (55.0%). Late-onset sepsis was significantly more common in very low birth weight and premature infants. The most frequently encountered pathogens in the early-onset group were group B streptococci (GBS) and Escherichia coli, while in the late-onset group, the organisms were coagulase-negative staphylococci and Enterobacteriaceae, including E. coli, Klebsiella pneumoniae, and Acinetobacter baumannii. GBS infection resulted in the highest mortality when the onset of sepsis was within the first 24 hours of life.  相似文献   
75.
A newly developed severe acute respiratory syndrome (SARS)-specific enzyme-linked immunosorbent assay (ELISA) was further validated to confirm cutoff values and evaluate its diagnostic performance with clinical samples. In parallel, an immunochromatographic test was also evaluated. A total of 227 clinical serum specimens collected from SARS patients were used in the study, together with 385 samples from healthy donors. By use of an immunofluorescent (IF) test as the “gold standard, ” both the ELISA and the immunochromatographic test were able to detect immunoglobulin G antibodies to SARS not only from late-convalescent-stage samples (>21 days from the onset of clinical symptoms), as previously established, but also from early-acute-phase samples (1 to 10 days from onset). The ELISA, using an optical density (OD) of 0.25 as its cutoff value, produced the best sensitivity while maintaining high specificity. It detected SARS-specific antibodies in 58, 70, 75, and 95%, respectively, of the four groups of samples collected from patients 1 to 10 days, 11 to 20 days, 21 to 30 days, and more than 30 days after the onset of clinical symptoms. Similarly, the immunochromatographic test detected SARS-specific antibodies in 55, 68, 81, and 79% of the four groups, respectively. The overall specificities for the ELISA and the rapid test were 99.5 and 97.7%, respectively. Although the positive correlation observed between the ELISA OD values and the IF titers was moderate (r = 0.6915; P < 0.001), the detection rates of both the ELISA and the rapid test were found well in agreement with the IF titers.  相似文献   
76.
An autopsy-proved case of AIDS in Taiwan   总被引:1,自引:0,他引:1  
The first case of AIDS positively identified in a non-foreigner in Taiwan was a 25-year-old unmarried male who had practiced homosexuality for ten years. The patient began to have abdominal pain accompanied with loose stools and weight loss in June 1985, followed by fever, cough, headache, dizziness, and loss of memory. Facial hyperpigmentation and extensive oroesophageal candidiasis were noted. Laboratory studies showed severe lymphopenia with a reversed T-helper to T-suppressor ratio, cutaneous anergy and polyclonal gammopathy. Human immunodeficiency virus (HIV) antibodies were positive by ELISA and Western blot, and the virus was isolated from the blood. At autopsy, disseminated cytomegalovirus infection, extensive CNS toxoplasmosis and early lesions of Kaposi's sarcoma were demonstrated. The detection of HIV in the adrenal medulla supports the consensus that the virus is neurotropic.  相似文献   
77.
A prospective observational study was conducted to evaluate the clinical characteristics and outcome of community-acquired anaerobic bacteremia. From June 1 2001 through May 31 2002, 52 patients with community-acquired anaerobic bacteremia were enrolled at the emergency department in a teaching hospital. There were 19 patients (34%) with polymicrobial bacteremia and Escherichia coli was the most common copathogen (n = 6). Of 62 anaerobic isolates, species of the Bacteroides fragilis group were the most common isolates (n = 28, 45%), followed by Clostridium spp. (n = 11, 18%). Among the 52 patients enrolled, up to 27% had underlying malignancy and the gastrointestinal tract accounted for 48% of the sources of infection. Clinical manifestations suggesting anaerobic infections were common and three-quarters (n = 39) of 52 patients received adequate empirical antimicrobial treatment. Documentation of anaerobic bacteremia seldom influenced antimicrobial treatment. The 30-day mortality was 25%. Although univariate analysis revealed that underlying malignancy (p=0.003), leukopenia (p=0.044) and absence of fever (p=0.047) were associated with mortality, only malignancy (p=0.007) was an independent risk factor in the multivariate analysis.  相似文献   
78.
Hematopoietic stem cell transplantation is currently the only curative therapy for beta-thalassemia major. However, <30% of patients have unaffected HLA-identical siblings to serve as donors. We investigated the feasibility of using umbilical cord blood transplants from unrelated HLA mismatched donors and a myeloablative preparative regimen that did not involve total body irradiation. Between October 2003 and November 2004, 5 children with beta-thalassemia major received busulfan, cyclophosphamide, and antithymocyte globulin before cord blood transplantation (median dose, 8.8 x 10(7) cells per kilogram of body weight) from unrelated donors (1 or 2 of 6 HLA antigens were mismatched) and were then evaluated for engraftment, adverse effects, and treatment outcome. The median times to neutrophil engraftment, red blood cell transfusion independence, and platelet engraftment were 12, 34, and 46 days after transplantation, respectively. All patients showed grade II or III acute graft-versus-host disease; none developed extensive chronic graft-versus-host disease until the date of last contact. All patients were alive at a median follow-up of 303 days after transplantation, with complete donor chimerism and transfusion independence. These results are encouraging and clearly show the feasibility of unrelated mismatched umbilical cord blood transplantation in the treatment of children with beta-thalassemia major.  相似文献   
79.
BACKGROUND: Misoprostol is an effective agent for pre-operative cervical priming before surgical termination of pregnancy in the first trimester. Previous studies have shown that both oral and vaginal routes are equally effective for such a purpose. This study aimed to compare a new route of sublingual administration to the vaginal route of administration for pre-operative cervical priming in first trimester surgical abortion. METHODS: Eighty women with gestational age <12 weeks were randomized by a computer-generated model to receive 400 micro g of misoprostol either sublingually or vaginally 3 h prior to vacuum aspiration. The primary outcome measure was the degree of cervical dilatation, and secondary outcomes included the force required to dilate the cervix from 3 to 8 mm, intra-operative blood loss and incidence of pre-operative side-effects. RESULTS: There was no significant difference in the baseline cervical dilatation (sublingual: 7.6 +/- 1.3 mm; vaginal: 7.7 +/- 0.73 mm), cumulative force required to dilate the cervix from 3 to 8 mm (sublingual: 9.0 +/- 9.8 N; vaginal: 6.6 +/- 5.4 N) and total blood loss (sublingual: 52.1 +/- 20.2 ml; vaginal: 48.3 +/- 12.3 ml). Pre-operative side-effects were also similar. CONCLUSIONS: Both sublingual and vaginal misoprostol are effective in cervical priming before surgical termination of pregnancy in the first trimester. Sublingual misoprostol has the advantage of being more convenient to administer and may be more suitable for day surgery.  相似文献   
80.
Lam PM  Leung TN  Haines C  Chung TK 《Maturitas》2003,45(2):99-107
OBJECTIVES: To evaluate the use of hormone replacement therapy (HRT), the prevalence of climacteric symptoms, and the knowledge about HRT. METHODS: A prospective study was conducted by telephone interview among a randomly selected population-based sample of 978 Hong Kong Chinese women aged 40-60 years. RESULTS: Of 414 women with a history of either natural or surgical menopause, 22 (5.3%) and 17 (4.1%), respectively, were either past or current users of HRT. The climacteric symptom scores of premenopausal women were significantly lower than those of perimenopausal women, but were comparable with those of postmenopausal women. The commonest climacteric symptom was 'muscle and joint pains' which was reported in 553 (56.6%) women, while only 228 (23.3%) and 151 (15.4%) women reported hot flushes and night sweating, respectively. Moreover, only 230 (23.5%) women realized that HRT could relieve menopausal symptoms and only 33 (3.4%) women were aware that HRT was protective against osteoporosis. In general, women with more climacteric symptoms, who had ever used HRT, and those with higher education level and higher family income, had better knowledge about HRT. CONCLUSIONS: Postmenopausal Hong Kong Chinese women have a low HRT usage rate and the majority of them are lacking of the knowledge about HRT.  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