全文获取类型
收费全文 | 21055篇 |
免费 | 444篇 |
国内免费 | 496篇 |
专业分类
耳鼻咽喉 | 598篇 |
儿科学 | 1343篇 |
妇产科学 | 394篇 |
基础医学 | 2090篇 |
口腔科学 | 713篇 |
临床医学 | 1112篇 |
内科学 | 4931篇 |
皮肤病学 | 371篇 |
神经病学 | 1535篇 |
特种医学 | 570篇 |
外科学 | 3598篇 |
综合类 | 220篇 |
一般理论 | 10篇 |
预防医学 | 2094篇 |
眼科学 | 492篇 |
药学 | 1246篇 |
中国医学 | 200篇 |
肿瘤学 | 478篇 |
出版年
2024年 | 3篇 |
2023年 | 20篇 |
2022年 | 52篇 |
2021年 | 79篇 |
2020年 | 80篇 |
2019年 | 102篇 |
2018年 | 127篇 |
2017年 | 54篇 |
2016年 | 128篇 |
2015年 | 71篇 |
2014年 | 112篇 |
2013年 | 53篇 |
2012年 | 1985篇 |
2011年 | 2246篇 |
2010年 | 503篇 |
2009年 | 260篇 |
2008年 | 1735篇 |
2007年 | 1990篇 |
2006年 | 1752篇 |
2005年 | 1885篇 |
2004年 | 1796篇 |
2003年 | 1725篇 |
2002年 | 1622篇 |
2001年 | 1085篇 |
2000年 | 1584篇 |
1999年 | 730篇 |
1998年 | 89篇 |
1997年 | 18篇 |
1996年 | 16篇 |
1995年 | 24篇 |
1994年 | 13篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1957年 | 1篇 |
1942年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Alvarez M García F Martínez NM Hernández Quero J Louwagie J De Brauwer A Maroto MC 《Journal of medical virology》2004,73(2):151-157
The changes in viral load and CD4(+) count at 3 and 6 months in a group of 166 HIV-infected patients was evaluated. The new therapy was chosen based on the medical history procedures for 70 patients, and in 96 patients it was guided by the partial or complete result of the line probe assay (LiPA) HIV RT and Protease resistance tests. The absolute difference from the baseline of the log viral load at 3 and 6 months was significantly different between the two groups when adjusted for baseline viral load (P < 0.0001) and stayed significant when intention-to-treat analysis was carried out (P < 0.001). The absolute difference of the CD4(+) count was not significantly different when adjusted for baseline CD4(+) (P = 0.854, 3 months; P = 0.06, 6 months). The proportion of patients with a viral load =200 cp/ml in the medical history group (14.5%, 3 months; 15.2%, 6 months) was significantly different from the proportion of responders in the LiPA group (28.7%, 3 months, P = 0.03; 34.7%, 6 months, P = 0.008). In the intention-to-treat population, the difference between the two groups remained significant (P = 0.01). There was no statistical difference between the two groups in terms of adherence (P = 0.88), number of drug failures (P = 0.12) and for the time since starting treatment (in years) (P = 0.48), but there was a significant difference for the number of new drugs in the new regimen (P < 0.0001) and for the pill burden of the treatment (P = 0.0006). A higher antiretroviral HIV treatment success guided by the LiPA HIV genotyping system than that based on the medical history only is reported. Of note, this study reached the same conclusions as previous studies, which all used sequencing. 相似文献
72.
Pérez-Costas E Meléndez-Ferro M Pérez-García CG Caruncho HJ Rodicio MC 《Journal of chemical neuroanatomy》2004,27(1):7-21
The expression of reelin, a large extracellular matrix glycoprotein, was studied in the brain of pre-spawning adult sea lampreys by immunohistochemistry using two monoclonal antibodies against this protein. Reelin immunoreactive (reln-ir) neurons were observed in the olfactory bulb, and pallial and subpallial regions in the telencephalon. In the diencephalon, reln-ir cells were observed in some hypothalamic nuclei, in the nucleus of Bellonci, and in the habenula. In the mesencephalon, this protein was detected in several nuclei related with the centrifugal visual system, although the optic tectum was devoid of immunoreactivity. The hindbrain showed several nuclei with immunopositive neurons, including the branchiomeric nerve motor nuclei and also some groups of non-giant cells of the reticular formation. The rostral spinal cord showed some immunopositive neurons mainly located in lateral and ventral positions. Overall, the pattern of distribution of reelin in the adult sea lamprey correlates with the previously reported in other adult vertebrates. Furthermore, the wide distribution of reelin in the adult lamprey brain is consistent with a possible existence of different roles for this protein not related with development in the central nervous system (CNS) of vertebrates (i.e. neuronal plasticity and/or maintenance). 相似文献
73.
The role of histopathology for diagnosing celiac disease (CD) has been recently challenged. However, based in our experience with roughly 4,600 distal duodenal and jejunal biopsies in children it is apparent that appropriate biopsy site, handling, processing, and microscopic evaluation result in a consistent pattern of microscopic changes which allows strong clinical-pathologic correlation. A simple way for establishing the villous/crypt (V/C) ratio is proposed. Normal mucosa displays a V/C ratio of 2.5 or more. Villous atrophy is then graded according to the V/C ratio as follows: Grade 1: 2.5-2; Grade 2: 1-2; Grade 3: 1-0.5, and Grade 4: less than 0.5. The grading should be done in areas of the biopsy where at least 2 to 3 crypts are present in almost its full length. CD disease was consistently associated with villous atrophy grades 3 and 4, which fully recovered or maintained Grade 1 after gluten-free diet. Grade 2 biopsies were rare and related to incomplete gluten-free diet. Patchy lesions were never seen as were patients with normal biopsies later developing mucosal atrophy. Histopathologic evaluation of mucosal biopsies to rule out CD requires adequate biopsy site (distal duodenum or proximal jejunum), and proper handling (oriented material), processing (cutting on edge) and interpretation. The proposed villous atrophy grading may help to adequately compare experiences from different centers as well as to reconcile apparent different findings in separate biopsies. In children histopathology keeps on having a central role for CD diagnosis. 相似文献
74.
In order to evaluate nutritional status by anthropometry, a group of elderly (60 to 83 years old) was studied: 63 institutionalized and 37 non-institutionalized elderly from Valencia city, Venezuela. Weight, height, triceps skinfold and mid-arm circumference were measured and the body mass index (weight/height2) was calculated. The average age for the institutionalized group was 77.3 +/- 7.5 years old and 69.5 +/- 7.6 years old for the free-living elderly group. Tricipital skinfold (TSF) and mid-arm circumference (MAC) means were within the normal reference range for both groups, without significant differences by sex. Body mass index (BMI) was higher in the institutionalized group. Lower BMI and MAC were found in older elderly (> or =80 y). According to the nutritional classification by BMI, 16% of nutritional deficit, 45% of normal status and 39.7% with of excess weight were found in institutionalized elderly; while in free-living elderly, prevalences were 8%, 62% and 29.7% respectively. Even though normal nutritional status was highly prevalent, institutionalized elderly showed higher prevalences of nutritional alterations (underweight and overweight). 相似文献
75.
Major histocompatibility complex status in breast carcinogenesis and relationship to apoptosis 总被引:2,自引:0,他引:2
Redondo M García J Villar E Rodrigo I Perea-Milla E Serrano A Morell M 《Human pathology》2003,34(12):1283-1289
Major histocompatibility complex (MHC) molecules are of central importance in regulating the immune response against tumors. In this study we used immunohistochemistry to study human leukocyte antigen (HLA) class I and II antigen expression in normal breast tissues and benign, preneoplastic, primary, and metastatic breast lesions using antibodies against beta-2-microglobulin (beta2-m), heavy-chain, and HLA-DR antigens. Whereas all normal tissues and benign lesions were positive for beta2-m and HLA-A, -B, and -C antigens, total loss of HLA class I antigens was found in 37% (11 of 30) of in situ carcinomas, in 43% (56 of 131) of the primary tumors, and in 70% (31 of 45) of the lymph node metastases. HLA-DR was also underexpressed in breast cancer cells; thus 20% (6 of 30) of in situ carcinomas, 15% of invasive carcinomas (20 of 131), and only 1 metastatic case were positive for this antigen. Both HLA class I and II antigen expression were more frequently down-regulated in metastatic lesions than in primary breast lesions (P <0.05), and a tendency toward a simultaneous defective expression of HLA class I and II antigens was observed in primary carcinomas (P = 0.07). However, no correlation was found between the expression of any of the aforementioned molecules and pathological parameters or survival. Interestingly, HLA class I expression was expressed more frequently in tissues with high apoptotic activity and was significantly associated with the expression of the proapoptotic bax gene (P = 0.02), and was inversely associated with expression of the antiapoptotic bcl-2 gene (P = 0.03). We conclude that alterations in HLA class I and II antigen expression are early events in breast carcinogenesis and play significant roles in metastatic progression. In addition, their expression is correlated with apoptosis-regulating proteins, which may influence the cytotoxicity of T cells against HLA class I-specific tumor antigens. 相似文献
76.
Villalba-Caloca J García-García Mde L Sifuentes-Osornio J Sada-Díaz E Salazar-Lezama MA 《Gaceta médica de México》2003,139(5):471-492
Tuberculosis is a public health problem. If the current trends continue, is expected to arrive to 10.2 million of new cases in 2005. There are three studies accomplished in 1995 in Mexican patients. The results show important difficulty in the application and the follow-up of the program of control of the tuberculosis, what has caused accumulation of chronic cases, moderate rate of primary resistance and alarming levels of primary and secondary multiresistance (23%). Mechanism of protective immunity against mycobacterium tuberculosis (MTB) in humans have not been clarified. Different subpopulations of lymphocytes CD4, CD8 and other populations as well as macrophages, and monocytes, have an important role. In industrialized countries, the managing of the MDRTB is based on the use of individualized treatments with second line drugs according to susceptibility test, however the foregoing has not been possible to apply it middle or low income countries. WHO has launches the initiative "DOTS plus" that consist in the administration of a standarized regimen on the basis of epidemiology of resistance in the country or region. 相似文献
77.
Carmona-Sánchez R Valdovinos-Díaz MA Facha MT Aguilar L Cachafeiro M Flores C Solana S Carrillo G Chapela R Mejía M Pérez-Chavira R Salas J 《Gaceta médica de México》1999,135(5):471-475
The prevalence of gastroesophageal reflux (GER) in asthmatic patients is elevated, but the exact frequency remains unknown. The relationship between GER and asthma has not been investigated in Mexico. The objective of this study is to know the frequency of GER in Mexican asthmatic patients and the possible relationship with the severity of asthma. Fifty patients with adult-onset asthma were studied. AII of them fulfill the diagnostic criteria of the National Institutes of Health, U.S. The evaluation included a symptoms questionnaire, spirometry, esophageal manometry, 24-h esophageal pH-recording, and an upper gastrointestinal endoscopy. Twenty-three patients had mild asthma (46%), 16 moderate (32%) and 11 had severe asthma (22%). Twenty-seven (54%) reported heartburn and regurgitation at least twice a week. The esophageal pH-recording showed pathologic GER in 37 subjects (74%) and endoscopic esophagitis was found in 7 cases (14%). The pH-recording showed pathologic GER in 13 patients with mild asthma (57%), in 13 with moderate asthma (81%) and in all patients with severe asthma (100%). The frequency of GER in Mexican asthmatic patients is high and increases proportionately with the severity of asthma. This factor must be considered in the integral evaluation of these patients. 相似文献
78.
Identification of two homologous antigenic peptides derived from L1 HPV-16 and 18 proteins specific for the HLA-B*3901 allele 总被引:1,自引:0,他引:1
Monroy-García A Weiss-Steider B Hernández-Montes J Ortiz-Navarrete VF Bañuelos-Pánuco A Acosta-Araujo A Díaz-Quiñónez A López-Graniel CM Herbert G Granados J de Leo C Silva-López RM Mora-García ML 《Archives of virology》2002,147(10):1933-1942
Summary. In this work we present evidence that the homologous peptides IHSMNSTIL and IHSMNSSIL derived from L1 HPV-16 and 18 proteins
respectively, and with high specificity for the allele HLA-B*3901, according with an algorithm prediction program, induced T cell stimulation in patients with advanced cervical cancer
positive for HPV-16 or 18 infection and for the HLA-B*3901 allele. Interestingly, T lymphocytes derived from a patient with HPV-18 infection and stimulated with the peptide IHSMNSTIL
were capable to kill a cervical cancer cell line named Rova, derived from the tumor of the same patient. In addition, the
cytotoxic activity was strongly increased when this cell line was previously treated with hrIFN-γ. These results suggest that
the CTL immune response to L1 HPV-16 and 18 protein derived epitopes is maintained in patients with advanced cervical cancer
within specific alleles, and opens the possibility that homologous epitopes may be used in the generation of prophylactic
vaccines for cervical tumors bearing different HPV-types.
Received March 4, 2002; accepted May 20, 2002 相似文献
79.
80.
Crombet T Torres O Rodríguez V Menéndez A Stevenson A Ramos M Torres F Figueredo R Veitía I Iznaga N Pérez R Lage A 《Hybridoma》2001,20(2):131-136
High levels of growth factors and their receptors have been demonstrated in human tumors. Gliomas and meningiomas are characterized by overexpression of epidermal growth factor receptor (EGF-R). Ior egf/r3, is a neutralizing murine monoclonal antibody (MAb) against EGF-R, and was generated at the Cuban Institute of Oncology. The antibody recognizes EGF-R with high affinity, inhibiting tyrosine kinase activation. A clinical trial was conducted in brain tumor patients to evaluate toxicity, immunogenicity, and clinical benefit of escalating doses of the antibody. Nine patients with histologically confirmed gliomas or meningiomas, who had active or recurrent disease after receiving conventional treatment, received four intravenous doses of ior egf/r3. Total dosages ranged from 160 to 480 mg. As inclusion criteria, radioimmunoscintigraphy with the same MAb labeled with 99mTechnetium (99mTc) was performed. Immune response against the murine antibody was also evaluated. After four doses of ior egf/r3 MAb, no significant toxicity was found, except in one patient who developed a grade 4 allergic adverse event. This reaction was probably related with previous sensitization to the same MAb and the development of human anti-mouse antibodies (HAMA) response. Despite no major objective antitumor responses, eight patients had stable disease on the 6-month evaluation, and two patients remain alive after four years of MAb therapy. 相似文献