全文获取类型
收费全文 | 55835篇 |
免费 | 3492篇 |
国内免费 | 1593篇 |
专业分类
耳鼻咽喉 | 330篇 |
儿科学 | 1786篇 |
妇产科学 | 872篇 |
基础医学 | 7941篇 |
口腔科学 | 908篇 |
临床医学 | 4384篇 |
内科学 | 8446篇 |
皮肤病学 | 813篇 |
神经病学 | 2451篇 |
特种医学 | 1028篇 |
外国民族医学 | 7篇 |
外科学 | 6394篇 |
综合类 | 7569篇 |
现状与发展 | 1篇 |
预防医学 | 4315篇 |
眼科学 | 496篇 |
药学 | 7230篇 |
31篇 | |
中国医学 | 2911篇 |
肿瘤学 | 3007篇 |
出版年
2023年 | 655篇 |
2022年 | 1473篇 |
2021年 | 1844篇 |
2020年 | 1583篇 |
2019年 | 2067篇 |
2018年 | 1914篇 |
2017年 | 1793篇 |
2016年 | 1671篇 |
2015年 | 1674篇 |
2014年 | 3022篇 |
2013年 | 3320篇 |
2012年 | 2794篇 |
2011年 | 3212篇 |
2010年 | 2488篇 |
2009年 | 2350篇 |
2008年 | 2354篇 |
2007年 | 2512篇 |
2006年 | 2254篇 |
2005年 | 2005篇 |
2004年 | 1799篇 |
2003年 | 1551篇 |
2002年 | 1336篇 |
2001年 | 1162篇 |
2000年 | 943篇 |
1999年 | 803篇 |
1998年 | 748篇 |
1997年 | 714篇 |
1996年 | 625篇 |
1995年 | 624篇 |
1994年 | 529篇 |
1993年 | 460篇 |
1992年 | 446篇 |
1991年 | 383篇 |
1990年 | 346篇 |
1989年 | 306篇 |
1988年 | 279篇 |
1987年 | 271篇 |
1985年 | 786篇 |
1984年 | 849篇 |
1983年 | 681篇 |
1982年 | 663篇 |
1981年 | 605篇 |
1980年 | 489篇 |
1979年 | 411篇 |
1978年 | 370篇 |
1977年 | 286篇 |
1976年 | 332篇 |
1975年 | 259篇 |
1974年 | 233篇 |
1973年 | 222篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Toshio Mizutani Ken-ichi Nakamura Mutsuo Enomoto Masuhiro Sakata Shigeo Yamada 《Neuropathology》1998,18(1):80-90
A neuropathological study on 1540 consecutive autopsy brains ranging from 60 to 107 years of age revealed the following points. (1) Of the of the demented cases of the plaque-predominant type, 93% were complicated with multiple tiny cortical infarcts. They showed a tendency for dementia to develop before or after the appearance or worsening of a systemic disorder such as cardiovascular disease, respiratory infection and cancer. However, there was no case showing Alzheimer-type dementia (ATD). (2) The plaque-predominant type might be an extreme condition of brain aging in terms of senile plaques (SP). It is likely that although the pathological appearance of SP alone is not responsible for dementia, its coexistence with multiple cortical infarcts could be the cause of dementia. Therefore, this type should be distinguished from ATD. (3) Primary hippocampal degeneration could also be an extreme condition of brain aging in terms of neurofibrillary tangles. This condition was different pathologically from the hippocampal lesion in ATD. (4) Several characteristics of old-old and oldest-old patients were clarified. 相似文献
72.
Murakami R Obara H Momota T Tanaka A Nakamura H Mikawa K Iwai S 《Journal of anesthesia》1989,3(2):149-154
Morphological alterations in the lungs of rats deficient in either or both of vitamin E and essential fatty acids were investigated after exposure to hyperoxia for 48h. In rats deficient in both vitamin E and essential fatty acids, there was damage to type-2 alveolar cells observed as swollen mitochondria and bleb formation in the cytoplasm. None of these changes was found in rats deficient in only one of these substances. Hyperoxia in rats deficient in both substance also caused destruction of the capillary endothelial cells and edema in the interstitium. The lungs of rats deficient in only one of the substances showed some edema in the capillary endothelial cells, but not destruction, and less interstitial edema. These findings suggest that simultaneous deficiency in vitamin E and essential fatty acids facilitates lung damage in rats exposed to hyperoxia.(Murakami R, Obara H, Momota T et al.: The effect of hyperoxia on the lungs of rats deficient in essential fatty acids. J Anesth 3: 149–154, 1989) 相似文献
73.
Effect of moderate exercise on salivary immunoglobulin A and infection risk in humans 总被引:3,自引:0,他引:3
Klentrou P Cieslak T MacNeil M Vintinner A Plyley M 《European journal of applied physiology》2002,87(2):153-158
The incidence of upper respiratory tract infections (URTI) and salivary immunoglobulin A concentrations [IgAs] of nine individuals were examined during 12 weeks of moderate exercise training, and compared to ten sedentary controls.
Changes in maximal oxygen uptake were assessed at initial, mid-point and final evaluations (T1–3), while changes in [IgAs] and salivary immunoglobulin concentration-salivary albumin concentration ratio ([IgAs]:[Albs]) were monitored at T1 and T3. During the 12 week period, symptoms of URTI were self-recorded daily. During the period of
training the level of fitness significantly increased (P<0.05) in the exercise group. The number of days recording symptoms of influenza, but not of cold, and total light URTI symptoms was significantly reduced in the exercise group during the last weeks of training. A significant increase in
[IgAs] and in [IgAs]:[Albs] was found in the exercise group after training. Both [IgAs] and [IgAs]:[Albs] were significantly related to the number of days showing symptoms of influenza (P<0.01) and the total number of days of sickness (P<0.05). These data provide quantitative support for the belief that regular, moderate exercise results in an increased [IgAs] at rest and [IgAs]:[Albs], which may contribute to a decreased risk of infection.
Electronic Publication 相似文献
74.
Background
The effect of the changes in the femoral posterior condylar offset (PCO) on anterior–posterior (AP) translation and internal–external (IE) rotation in cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) remains unknown. The purpose of this study was to compare the kinematics in CR and PS TKA with respect to the difference in prosthetic design and PCO change through a computational simulation.Methods
We developed three-dimensional finite element models with the different PCOs of ± 1, ± 2 and ± 3?mm in the posterior direction using CR and PS TKA. We performed the simulation with different PCOs under a deep knee bend condition and evaluated the kinematics for the AP and IE in CR and PS TKA.Results
The more tibiofemoral (TF) translation in the posterior direction was found as PCO translated in posterior direction for both CR and PS TKA compared to the neutral position. However, the change of the AP translation with respect to the PCO change in CR TKA was greater than PS TKA. The more TF external rotation was found as PCO translated in the anterior direction for both CR and PS TKA compared to the neutral position. However, unlike the TF translation, the TF rotation was not influenced by the PCO change in both CR and PS TKA.Conclusion
The PCO magnitude was influenced by a postoperative change in the kinematics in CR TKA although a relatively smaller effect was observed in PS TKA. Hence, surgeons should be aware of the PCO change, especially for CR TKA. 相似文献75.
The pre-B cell receptor (preBCR) plays critical roles in early B cell differentiation. It has been shown that not all muH chains are capable of pairing with surrogate light (SL) chains to form preBCR. Here, we established a novel system to differentially identify two types of early pre-B cell populations in bone marrow and fetal liver of mice, one producing SL-pairing muH chains and the other producing SL-non-pairing muH chains. The former population accounted for 80% of all the early pre-B cells in adult bone marrow, while it accounted for only 20% of those in fetal liver. Comparison of the two types of pre-B cell populations in fetal liver revealed the structural difference between SL-pairing and -non-pairing muH chains encoded by the V(H)81X segment that was most frequently utilized in fetal liver pre-B cells but rarely expressed by B cells generated in adults. PreBCR played an important role in the positive selection of V(H)81X-muH chains carrying the characteristic sequences of the complementarity-determining region 3 with little or no nibbling or N nucleotide addition, leading to their predominance in neonatal splenic B cells. These fetal-type V(H)81X-muH chains were also detected in adult spleen, but almost exclusively in marginal zone (MZ) B cells in contrast to the adult-type V(H)81X-muH chains. This strongly suggests that neonatally generated and selected B cells expressing the stereotyped V(H)81X-muH chains are maintained in the adult MZ and could function as innate-like lymphocytes. 相似文献
76.
N Lügering R Stoll T Kucharzik G Burmeister C Sorg W Domschke 《Clinical and experimental immunology》1995,101(2):249-253
MRP8 and MRP14 are myeloic related proteins expressed by most circulating and emigrated neutrophils and monocytes. Their composite molecule MRP8/14 (27E10 antigen) was shown to exhibit striking antimicrobial properties. The aim of the present study was to assess the value of MRPs as markers for detection of the different stages of HIV infection (Centres for Disease Control and Prevention, 1993). By employing the ELISA technique we measured serum concentrations of these proteins in samples from 122 HIV patients at the various stages of disease, and the results were compared with those for healthy controls. Serum levels of the heterodimeric molecule 27E10 were significantly increased (P < 0.001) in patients with CDC stages II and III, with the highest levels being in patients with stage III and acute ongoing opportunistic infections. For the single component MRP14, significantly raised levels (P < 0.05) were only found in HIV stage III individuals with acute clinical events. Similar associations were not found for MRP8 alone. Increase was not related to CD4+ cell count. There was a significant correlation between 27E10 antigen serum concentrations and levels of neopterin in patients with HIV stages II and III without acute concurrent illness. Patients being treated with Zidovudine showed no statistically significant variation in levels of 27E10 and its single components MRP8 and MRP14 compared with untreated patients. These findings suggest that elevation of MRP14 levels occurs in HIV+ individuals at later stages post-HIV infection, after the onset of opportunistic infections. 27E10 antigen is concluded to be a potential marker for the different stages of HIV disease. 相似文献
77.
Monoclonal antibodies against human granulocytes and myeloid differentiation antigens 总被引:4,自引:0,他引:4
Patrice Mannoni Anna Janowska-Wieczorek A. Robert Turner Locksley McGann Jean-Michael Turc 《Human immunology》1982,5(4):309-323
Monoclonal antibodies (MCA) were obtained by immunizing BALB/c mice with 99% pure granulocytes from normal donors or with a whole leukocyte suspension obtained from a chronic myelogenous leukemia (CML) patient, and then fusing the mouse spleen cells with a 315–43 myeloma cell clone. Four MCA were selected and studied using ELISA, immunofluorescence, cytotoxicity assays, and FACS analysis. Antibodies 80H.1. 80H.3. and 80H.5 (from normals) and 81H.1 (from CML) detected antigens expressed on neutrophils. Antibodies 80H.1 and 80H.3 (lgG) also reacted with monocytes but not with other blood cell subsets. Antibodies 80H.5 and 81H.1 (lgM) were cytotoxic and reacted strongly with most of the cells of the neutrophil maturation sequence. i.e., myeloblasts, promyelocytes, myelocytes, and mature granulocytes. Antibodies 80H.5 and 81H.1 also inhibited BFU-GM and CFU-E. Antigens recognized by 80H.3. 80H.5, and 81H.1 were expressed both on a proportion of cells from HL.60, KG.1, ML.1, and K562 myeloid cell lines, and on a proportion of blast cells isolated from patients with acute myelogenous leukemia. They were not found on lymphoid cell lines or lymphoid leukemia cells. These MCA recognize either late differentiation antigens expressed on mature neutrophils and monocytes (80H.1 and 80H.3) or early differentiation antigens (80H.5 and 81H.1) specific to the granulocytic lineage. They may be useful for a better definition of those antigens specific to hematopoietic stem cells and their relationship with normal or neoplastic hematopoiesis. 相似文献
78.
The major histocompatibility complex (CyLA) of the cynomolgus monkey. I. Serologic definition of 21 specificities 总被引:1,自引:0,他引:1
Thirty-seven lymphocytotoxic antisera, 27 of which were raised by immunization with skin grafts and blood from partially matched donors, were tested against cells obtained from 218 unrelated animals and 205 offspring from a colony of cynomolgus monkey (Macaca fascicularis). Evidence was obtained for the presence of at least 21 specificities defined by cluster analysis and segregation within families. Allelic relationships between 16 specificities was suggested by segregation patterns, the absence of triplets and statistical analysis of association in the unrelated population sample. The data support a two-locus model, with tentative assignment of seven specificities to the A locus and six to the B locus. That these lymphocyte alloantigens constitute the major histocompatibility complex (MHC) of the cynomolgus monkey is suggested by analogy with other known MHCs and by the increased survival times of skin grafts between paternally matched half sibs compared to haplodistinct full sibs. 相似文献
79.
80.
Kazuo Umetsu Isao Yuasa Takao Yamashita Susumu Saito Tomio Yamaguchi Srinama B. Ellepola Takafumi Ishida Tsuneo Suzuki 《Journal of human genetics》1989,34(3):195-202
The genetic polymorphism of orosomucoid (ORM) and alpha-2-HS-glycoprotein (AHSG) were studied in Thai, Sri Lankan and Paraguayan populations using isoelectric focusing. Gene frequencies in these populations were compared with those in other populations. Four new ORM variants were detected:ORM1
*
15 in Thai,ORM1
*
16 in Paraguayan,ORM2
*
21 andORM2
*
22 in Sri Lankan. 相似文献