全文获取类型
收费全文 | 45897篇 |
免费 | 4179篇 |
国内免费 | 54篇 |
专业分类
耳鼻咽喉 | 525篇 |
儿科学 | 1303篇 |
妇产科学 | 1062篇 |
基础医学 | 5938篇 |
口腔科学 | 1042篇 |
临床医学 | 5293篇 |
内科学 | 8701篇 |
皮肤病学 | 688篇 |
神经病学 | 4891篇 |
特种医学 | 2036篇 |
外国民族医学 | 4篇 |
外科学 | 6316篇 |
综合类 | 755篇 |
一般理论 | 34篇 |
预防医学 | 4374篇 |
眼科学 | 1177篇 |
药学 | 3123篇 |
4篇 | |
中国医学 | 55篇 |
肿瘤学 | 2809篇 |
出版年
2021年 | 585篇 |
2019年 | 552篇 |
2018年 | 641篇 |
2017年 | 552篇 |
2016年 | 557篇 |
2015年 | 650篇 |
2014年 | 873篇 |
2013年 | 1394篇 |
2012年 | 1936篇 |
2011年 | 2043篇 |
2010年 | 1143篇 |
2009年 | 1020篇 |
2008年 | 1826篇 |
2007年 | 2044篇 |
2006年 | 1936篇 |
2005年 | 1835篇 |
2004年 | 1794篇 |
2003年 | 1664篇 |
2002年 | 1702篇 |
2001年 | 1527篇 |
2000年 | 1552篇 |
1999年 | 1365篇 |
1998年 | 540篇 |
1997年 | 510篇 |
1996年 | 484篇 |
1995年 | 463篇 |
1994年 | 409篇 |
1993年 | 352篇 |
1992年 | 1158篇 |
1991年 | 1163篇 |
1990年 | 1090篇 |
1989年 | 1098篇 |
1988年 | 910篇 |
1987年 | 1029篇 |
1986年 | 955篇 |
1985年 | 962篇 |
1984年 | 762篇 |
1983年 | 621篇 |
1982年 | 399篇 |
1981年 | 370篇 |
1980年 | 374篇 |
1979年 | 700篇 |
1978年 | 524篇 |
1977年 | 446篇 |
1976年 | 460篇 |
1975年 | 399篇 |
1974年 | 520篇 |
1973年 | 455篇 |
1972年 | 383篇 |
1971年 | 363篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Fragment length polymorphisms among independent isolates of Epstein-Barr virus from immunocompromised and normal hosts 总被引:9,自引:0,他引:9
DNA restriction fragment length polymorphisms of Epstein-Barr virus (EBV) DNA were used as a molecular epidemiological tool to study multiple isolates of virus from the same and different individuals. We studied 35 EBV isolates: 19 from seven immunocompromised children and 16 from seven college students with mononucleosis. Analysis of the fragment length polymorphisms in this collection of isolates permitted several conclusions. Sites of polymorphism were most often encountered in regions with repetitive DNA. Epidemiologically unrelated patients harbored viruses that could be readily distinguished; by contrast, two infants and their mothers harbored similar viruses. Isolates from different sites in the same patient were similar. Variations between different clinical isolates of EBV mimic those found between different laboratory strains of the virus. Fragment length polymorphisms thus provide a useful marker for studying transmission and pathogenesis of EBV infections. 相似文献
82.
Occurrence of the t(2;5)(p23;q35) in non-Hodgkin's lymphoma 总被引:9,自引:3,他引:6
Weisenburger DD; Gordon BG; Vose JM; Bast MA; Chan WC; Greiner TC; Anderson JR; Sanger WG 《Blood》1996,87(9):3860-3868
Primary CD30(Ki-1)-positive anaplastic large-cell lymphoma (ALCL) is considered by some to be a distinct clinicopathologic entity associated with the t(2;5) (p23;q35). However, the specificity of t(2;5) for ALCL has not been carefully studied. Therefore, we performed a detailed analysis of all cases of ALCL with abnormal cytogenetics results in the Nebraska Lymphoma Study Group registry, as well as all other cases of non-Hodgkin's lymphoma with t(2;5) in the registry. We found the t(2;5) in only five of 10 cases of ALCL, four of whom were young patients. However, we also found the t(2;5) in 11 other cases of nonanaplastic lymphoma, including eight children with typical peripheral T-cell lymphomas of various types. The t(2;5) was also found in three older adults with B-cell lymphomas of various types. Thus, the t(2;5) was not specific for CD30+ ALCL. However, t(2;5) may define a clinicopathologic entity in children and young adults characterized by variable morphologies with a T-cell or indeterminate phenotype, CD30-positivity, nodal disease with frequent extranodal involvement, advanced stage, and an excellent response to therapy, including bone marrow transplantation for relapsed disease. The clinical relevance of the t(2;5) in older patients requires further study. 相似文献
83.
84.
Metallic stents have been used in the management of prostatic disease in patients unfit for surgery. A variety of stents have become available but the optimum design and metal of construction has not yet been defined. This study examined one of the potential complications of stent insertion by demonstrating that they are susceptible to encrustation. Using an in vitro model it compares the ability of the different materials used in their construction to resist this encrustation. Titanium appears less able to resist deposition than the other metals examined. The long-term complication of encrustation may inhibit the use of some of these stents. 相似文献
85.
Ileocutaneous fistula formation following laparoscopic polypropylene mesh hernia repair 总被引:6,自引:1,他引:5
A rare case of enterocutaneous fistula caused by chronic erosion of polypropylene mesh after laparoscopic repair of a recurrent
inguinal hernia is described. Successful treatment was achieved by fistulectomy, total resection of the implanted mesh, and
small-bowel segmental resection. The patient recovered well postoperatively, and at follow-up 18 months later, the herniorrhaphy
has remained intact. This complication needs to be added to the differential diagnosis in patients who present inflammation,
abscess formation, or cutaneous fistula following laparoscopic hernia repair.
Received: 7 October 1996/Accepted: 14 October 1996 相似文献
86.
D J Martin B D Schoub G B Miller J G Sim 《Suid-Afrikaanse tydskrif vir geneeskunde》1990,78(9):533-535
The diagnostic and therapeutic implications of human immunodeficiency virus (HIV) infection and tuberculosis in South Africa, where tuberculosis remains a major health problem, are reviewed. Mycobacterium tuberculosis is a high-grade pathogen and is able to establish infection early in immunodeficiency. With HIV infection showing significant entry into the heterosexual population in the RSA, an increasing number of cases with both infections can be expected to occur. The radiological appearance in combined infection is variable, ranging from a formal cavitatory picture to the more common finding of diffuse pulmonary infiltration. Intrathoracic adenopathy is a more specific sign of tuberculosis in HIV infection, since it is not associated with persistent generalised lymphadenopathy and pulmonary opportunistic infections, such as Pneumocystis carinii pneumonia. Intercurrent pneumonic infections and other pulmonary manifestations of HIV disease render the interpretation of new infiltrates on chest radiography problematical. Tuberculin skin testing remains useful in HIV infection and should be performed in all HIV-infected patients. The value of tuberculosis serology still remains questionable. Standard antituberculosis drug regimens are effective, but maintenance treatment must be continued for life and should include isoniazid and rifampicin. BCG vaccination is recommended routinely at birth in infants with HIV infection and for asymptomatic HIV-infected individuals who have not previously been immunised. 相似文献
87.
Simultaneous assay of felbamate plus carbamazepine, phenytoin, and their metabolites by liquid chromatography with mobile phase optimization 总被引:1,自引:0,他引:1
Felbamate is an investigational antiepileptic drug (AED) in clinical trials. A high-performance liquid chromatographic method for the simultaneous analysis of felbamate, phenytoin (PHT), 5-(p-hydroxyphenyl)-5-phenylhydantoin, carbamazepine (CBZ), carbamazepine-10,11-epoxide, and carbamazepine-10,11-diol in serum was developed by a mobile phase optimization technique. Capacity factors for the compounds of interest and 12 other AEDs and metabolites were determined with mixtures of methanol, acetonitrile, or tetrahydrofuran and a 0.01 M ammonium phosphate buffer, pH 6.5, on a reversed-phase C8 column. An optimized mobile phase composition was determined that could separate the compounds of interest and three internal standards in less than 15 min. Serum was extracted with CH2Cl2/ethyl acetate (2:1) after addition of three internal standards. The method was validated for within-day and between-day precision and accuracy for the six compounds. Coefficients of variation were generally less than 10% at all concentrations and less than 5% in the typical therapeutic range for each compound. The lower limit of detection was estimated at 0.2 micrograms/ml for CBZ and its metabolites and 0.5 micrograms/ml for felbamate and PHT. For felbamate, the lowest point on the standard curve was 1.88 micrograms/ml with a between-day variability of 10.3%. The assay was used to determine the serum concentrations of PHT and CBZ and its metabolites in a subject before, during, and after felbamate therapy. 相似文献
88.
Granulomatous Pneumocystis carinii pneumonia in a patient with the acquired immunodeficiency syndrome. 总被引:2,自引:2,他引:0
下载免费PDF全文
![点击此处可从《Thorax》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A patient with an unusual granulomatous response to infection with Pneumocystis carinii is described. The diagnosis was made by open lung biopsy after two negative bronchoalveolar lavages. 相似文献
89.
This article examines the drug relatedness of violent events reported by White, Black, and Hispanic male and female street drug users from New York City. The primary purpose is to determine if the drugs-violence relationship varies for these different populations of drug abusers. Drug relatedness is assessed according to a tripartite conceptual model of the general relationship between drugs and violence. Significant race/ethnicity and gender differences were found in regard to the number of violent events manifesting specific drug-related dimensions of violence, the drugs associated with these violent events, and the primary reasons for the occurrence of these events. The implications of these findings are discussed. 相似文献
90.
Adequacy of hormone replacement therapy for osteoporosis prevention assessed by serum oestradiol measurement, and the degree of association with menopausal symptoms.
下载免费PDF全文
![点击此处可从《The British journal of general practice》网站下载免费的PDF全文](/ch/ext_images/free.gif)
BACKGROUND: Patients on hormone replacement therapy (HRT) for osteoporosis prevention rather than menopausal symptom control may be asymptomatic, despite inadequate replacement and low serum oestradiol (E2) levels. In the primary health care setting, therapeutic monitoring of HRT is not carried out routinely so that patients with serum E2 levels inadequate to protect bone may be missed. AIM: To determine the proportion of women on transdermal E2 preparations with serum E2 levels insufficient to protect bone and to assess the value of a questionnaire-derived menopausal symptom score (MSS) for detecting these patients. METHOD: A cross-sectional analysis of 45 patients aged 35-70 years using transdermal E2 preparations obtained from a computer register of 14500 patients in a suburban practice. One blood sample was obtained from each patient at the time the MSS questionnaire was completed. Serum E2 concentration was measured using a fluoroimmunoassay and compared with the MSS. Levels below 150 pmol/l were considered to be insufficient to protect bone. The diagnostic accuracy of the MSS in screening for levels below 150 pmol/l was determined using receiver operating characteristic (ROC) curve analysis. RESULTS: The median (95% CI) serum E2 was 147 pmol/l (126-198 pmol/l) and levels were below 150 pmol/l in 24 out of 45 patients. There was no difference in the MSS (median, 95% CI) between those with serum E2 < 150 pmol/l (8.5, 5.0-17) and > or = 150 pmol/l (9.0, 5.0-14; P = 0.477). The degree of association between the serum E2 and the MSS, using the Spearman rank correlation coefficient, rs (95% CI) was small and not significant (-0.04, -0.34 to 0.26; P = 0.398). ROC curve analysis revealed an area under the curve (95% CI) of 0.51 (0.33-0.68). CONCLUSIONS: More than half the women were inadequately replaced to protect against osteoporosis. Furthermore, the MSS was of no value in screening for those with low serum E2 levels. Serum E2 levels should be monitored in women on HRT for osteoporosis prevention and the E2 dosage adjusted accordingly. 相似文献