全文获取类型
收费全文 | 26914篇 |
免费 | 2064篇 |
国内免费 | 83篇 |
专业分类
耳鼻咽喉 | 351篇 |
儿科学 | 795篇 |
妇产科学 | 543篇 |
基础医学 | 3478篇 |
口腔科学 | 351篇 |
临床医学 | 2611篇 |
内科学 | 5874篇 |
皮肤病学 | 399篇 |
神经病学 | 2550篇 |
特种医学 | 1144篇 |
外科学 | 4744篇 |
综合类 | 271篇 |
现状与发展 | 1篇 |
一般理论 | 51篇 |
预防医学 | 1971篇 |
眼科学 | 410篇 |
药学 | 1323篇 |
中国医学 | 37篇 |
肿瘤学 | 2157篇 |
出版年
2023年 | 275篇 |
2022年 | 442篇 |
2021年 | 1267篇 |
2020年 | 673篇 |
2019年 | 982篇 |
2018年 | 1179篇 |
2017年 | 814篇 |
2016年 | 789篇 |
2015年 | 957篇 |
2014年 | 1311篇 |
2013年 | 1586篇 |
2012年 | 2342篇 |
2011年 | 2276篇 |
2010年 | 1235篇 |
2009年 | 969篇 |
2008年 | 1502篇 |
2007年 | 1565篇 |
2006年 | 1369篇 |
2005年 | 1254篇 |
2004年 | 1063篇 |
2003年 | 900篇 |
2002年 | 761篇 |
2001年 | 183篇 |
2000年 | 154篇 |
1999年 | 171篇 |
1998年 | 157篇 |
1997年 | 133篇 |
1996年 | 140篇 |
1995年 | 116篇 |
1994年 | 83篇 |
1993年 | 87篇 |
1992年 | 115篇 |
1991年 | 116篇 |
1990年 | 113篇 |
1989年 | 120篇 |
1988年 | 101篇 |
1987年 | 99篇 |
1986年 | 92篇 |
1985年 | 96篇 |
1984年 | 99篇 |
1983年 | 85篇 |
1982年 | 97篇 |
1981年 | 80篇 |
1980年 | 66篇 |
1979年 | 82篇 |
1978年 | 86篇 |
1977年 | 46篇 |
1975年 | 41篇 |
1974年 | 44篇 |
1973年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
Eleven "pure" borderlines, ten borderlines with depression, 16 "pure" depressives, and 31 normal subjects were compared on a number of standardized inventories of anxiety. While patient groups experienced more anxiety of all types than did normals, borderlines did not emerge as more anxious than other patient groups. Qualitative differences in the anxiety experienced by borderlines and nonborderlines are discussed. 相似文献
94.
Summary The relationship between plasminogen activator (PA)/plasminogen activator inhibitor (PAI) activity and morphological differentiation was investigated in human neuroblastoma (NB) cells treated with retinoic acid (RA). Conditioned medium from nine NB cell lines and one closely related neuroepithelioma line was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and zymography. All NB cell lines were shown to secrete urokinase (UK)-type PA (mol. wt., 52 kDa), and all except two produced tissue PA (mol. wt., 65 kDa). Identification of the PAs was made based on molecular weight and sensitivity to inhibition by anti-UK and anti-tPA antibodies. Several cell lines expressed PA inhibitory molecules; two molecular-weight forms were observed (35 and 40 kDa) in different cell lines. Complex formation with[125]I-labelled proteases revealed specific binding with UK and trypsin but not thrombin, plasmin, or kallikrein. After treatment for 6 days with 1 M RA, six of the cell lines exhibited an increase in cell-associated and/or secreted tPA activity, corresponding to morphological differentiation of the cells as manifested by extensive neurite outgrowth. A decrease in UK and UK-complex secretion was observed in several of these cell lines. Three cell lines exhibiting no detectable morphological alterations with RA treatment also showed no dramatic changes in PA/PAI activity. These results suggest that morphological differentiation of NB cells may be associated with alterations in the regulation of PA activity.Abbreviations NB
neuroblastoma
- RA
retinoic acid
- PA
plasminogen activator
- PAI
plasminogen activator inhibitor
- SDS
sodium dodecyl sulfate
- UK
urokinase
- tPA
tissue plasminogen activator 相似文献
95.
Mosaic ring 12p and total anomalous pulmonary venous return 总被引:1,自引:0,他引:1
Harris DL Siu BL Hummel M Harbert K Senft J Sargent L Wenger SL 《American journal of medical genetics. Part A》2004,131(1):91-93
An infant born with total anomalous pulmonary venous return (TAPVR) was found to have an extra chromosome present as a small ring. Spectral karyotyping and FISH analysis identified the material as a duplication involving the short arm of chromosome 12. Previous cases describing a variety of cytogenetic abnormalities that have been associated with TAPVR are reviewed along with prior cases of duplication 12p with their associated findings. We believe ours is the first case to report the occurrence of mosaic ring 12p and its association with TAPVR. 相似文献
96.
The clinical and pathological features of a case of malakoplakia of the adrenal gland occurring in a woman with Escherichia coli infection are described. This lesion mimicked a neoplasm, the true diagnosis only being revealed by histological examination. The light and electron microscopic features are described and it is suggested that malakoplakia is due to an abnormal macrophage response to E coli infection. 相似文献
97.
Jonathan D. Katz Parunag Nishanian Ronald Mitsuyasu Benjamin Bonavida 《Journal of clinical immunology》1988,8(6):453-458
The acquired immunodeficiency syndrome (AIDS) is defined in clinical terms by the development of Kaposi's sarcoma and/or severe opportunistic infections in persons without predisposing conditions. A hallmark of the syndrome has been a decrease in the number of CD4+ T helper cells. The reduction in the frequency of the CD4+ lymphocytes has been postulated to be primarily the result of human immunodeficiency virus (HIV) tropism and cytophathogenicity for the T-cell subset. Yet only a small percentage of cells is actually infected with HIV. Recently, we provided evidence indicating that AIDS patients' natural killer cells can mediate normal levels of antibody-dependent cellular cytotoxicity (ADCC) despite exhibiting a defect in natural killer (NK) effector function (J Immunol 139:55, 1987). This finding prompted us to investigate whether AIDS patients' effector cells could mediate ADCC against circulating CD4+ T cells infected with or expressing HIV antigen. The findings reported herein demonstrate that AIDS effector cells can mediate lysis of CEM (CD4+ T-cell line) coated with HIV protein in the presence of HIV-specific antibody. Lysis was specific, as non-HIV-coated CEM or the addition of HIV-negative serum resulted in no lysis. We then examined HIV-coated peripheral blood-derived CD4+ T lymphocytes as targets in ADCC. We demonstrate that in the presence of HIV-specific antibody, HIV-coated CD4+ T lymphocytes serve as targets for ADCC by AIDS effector cells. The lytic activity obtained with AIDS effector cells was comparable to that obtained with normal effector cells. These results demonstrate that AIDS effector cells can mediate ADCC against HIV-coated CD4+ T lymphocytes and suggest that ADCC may play a rolein vivo in the pathogenesis of AIDS. 相似文献
98.
Fidder HH Olschwang S Avidan B Zouali H Lang A Bardan E Picard O Bar-Meir S Colombel JF Chowers Y 《American journal of medical genetics. Part A》2003,(3):240-244
Ulcerative colitis (UC) and Crohn's disease (CD) are heterogeneous disorders characterized by chronic intestinal inflammation. Genetic predisposition is a major risk factor in both diseases. The CARD15 (NOD2) gene has been implied as a candidate gene in the pathogenesis CD. Our aim was to delineate the frequency of three missense and one frameshift variant of CARD15 in Israeli Jewish CD and UC patients. DNA was extracted from blood samples from 238 unrelated inflammatory bowel disease (IBD) patients, 68 with UC and 170 with CD. The DNA was genotyped for two missense mutations, R675W and G881R, and one frameshift mutation, 980FS981X. Mutations in CARD15 were observed with significantly greater frequency in CD patients (46/170, 27%) than in UC patients (7/68, 10%) (P = 0.005). Homozygous and compound heterozygous carriers were restricted to seven (4%) patients with CD as compared to none of the UC patients (P = 0.01). Similar rates in Ashkenazi and non-Ashkenazi Jewish patients were observed. Age-of-onset of disease was lower in Ashkenazi mutation carriers as compared to non-carriers of Ashkenazi origin (18.7 +/- 8.6 years vs. 25.8 +/- 13.4 years, respectively, P = 0.03). No other phenotypic characteristics could distinguish mutation carriers from non-carriers. We conclude that germline mutations in the CARD15 gene are more frequently found in CD than UC patients and appear to predict an earlier age-of-onset in Ashkenazi Jewish patients. No association could be demonstrated between CARD15 mutations and specific disease course or behavior. 相似文献
99.
100.
Developmental Progression in Children's Knowledge of AIDS: Implications for Education and Attitudinal Change 总被引:1,自引:1,他引:1
Osborne Mary L.; Kistner Janet A.; Helgemo Benjamin 《Journal of pediatric psychology》1993,18(2):177-192
The effectiveness of curricula designed to enhance a child'sunderstanding of AIDS may hinge partially upon incorporatinginformation adjusted to the child's developmental status. Accordingly,we examined the developmental progression of children's understandingof illness transmission in general and AIDS in particular, aswell as explored the relation between a child's knowledge ofAIDS and his/her attitudes toward persons with AIDS. Knowledgeof AIDS was manipulated through use of a brief educational intervention.Results support a developmental progression in knowledge aboutAIDS that is consistent with progressions related to illnessesin general. Knowledge enhancement was associated with positivechanges in attitude. 相似文献