全文获取类型
收费全文 | 11464篇 |
免费 | 928篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 352篇 |
妇产科学 | 343篇 |
基础医学 | 1243篇 |
口腔科学 | 377篇 |
临床医学 | 1027篇 |
内科学 | 2404篇 |
皮肤病学 | 371篇 |
神经病学 | 1107篇 |
特种医学 | 629篇 |
外国民族医学 | 19篇 |
外科学 | 1442篇 |
综合类 | 147篇 |
一般理论 | 4篇 |
预防医学 | 964篇 |
眼科学 | 550篇 |
药学 | 624篇 |
中国医学 | 3篇 |
肿瘤学 | 723篇 |
出版年
2021年 | 115篇 |
2020年 | 96篇 |
2019年 | 140篇 |
2018年 | 191篇 |
2017年 | 129篇 |
2016年 | 138篇 |
2015年 | 135篇 |
2014年 | 207篇 |
2013年 | 332篇 |
2012年 | 454篇 |
2011年 | 460篇 |
2010年 | 235篇 |
2009年 | 234篇 |
2008年 | 396篇 |
2007年 | 458篇 |
2006年 | 429篇 |
2005年 | 492篇 |
2004年 | 439篇 |
2003年 | 407篇 |
2002年 | 401篇 |
2001年 | 364篇 |
2000年 | 412篇 |
1999年 | 326篇 |
1998年 | 133篇 |
1997年 | 95篇 |
1995年 | 105篇 |
1992年 | 270篇 |
1991年 | 283篇 |
1990年 | 278篇 |
1989年 | 287篇 |
1988年 | 267篇 |
1987年 | 314篇 |
1986年 | 283篇 |
1985年 | 245篇 |
1984年 | 218篇 |
1983年 | 205篇 |
1982年 | 120篇 |
1981年 | 100篇 |
1980年 | 110篇 |
1979年 | 194篇 |
1978年 | 141篇 |
1977年 | 102篇 |
1976年 | 123篇 |
1975年 | 109篇 |
1974年 | 140篇 |
1973年 | 150篇 |
1972年 | 128篇 |
1971年 | 98篇 |
1970年 | 105篇 |
1969年 | 102篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
Multiple pathways to tumor immunity and concomitant autoimmunity 总被引:5,自引:0,他引:5
Mary Jo Turk Jedd D. Wolchok José A. Guevara-Patino Stacie M. Goldberg Alan N. Houghton 《Immunological reviews》2002,188(1):122-135
Summary: The immune repertoire contains T cells and B cells that can recognize autologous cancer cells. This repertoire is directed against self, and in some cases altered self (mutations). Priming immune responses against self antigens can be difficult. Strategies are presented using altered self to elicit immunity against self in poorly immunogenic tumor models. Mechanisms underlying immunity to self antigens on cancer cells show that the immune system can use diverse strategies for cancer immunity, in both the immunization and the effector phases. CD4+ T cells are typically, but not always, required for immunization. The effector phase of tumor immunity can involve cytotoxic T cells, macrophages with activating Fc receptors, and/or killer domain molecules. This diversity in the effector phase is observed even when immunizing with conserved paralogs. A consequence of tumor immunity is potentially autoimmunity, which may be undesirable. Autoimmunity uses similar mechanisms as tumor immunity, but tumor immunity and autoimmunity can uncouple. These studies open up strategies for active immunization against cancer. 相似文献
93.
Isolation of a new clathrin heavy chain gene with muscle-specific expression from the region commonly deleted in velo-cardio-facial syndrome 总被引:3,自引:4,他引:3
Sirotkin H; Morrow B; DasGupta R; Goldberg R; Patanjali SR; Shi G; Cannizzaro L; Shprintzen R; Weissman SM; Kucherlapati R 《Human molecular genetics》1996,5(5):617-624
Velo-cardio-facial syndrome (VCFS) and DiGeorge syndrome (DGS) are
developmental disorders characterized by a spectrum of phenotypes including
velopharyngeal insufficiency, conotruncal heart defects and facial
dysmorphology among others. Eighty to eighty-five percent of VCFS/DGS
patients are hemizygous for a portion of chromosome 22. It is likely that
the genes encoded by this region play a role in the etiology of the
phenotypes associated with the disorders. Using a cDNA selection protocol,
we isolated a novel clathrin heavy chain cDNA (CLTD) from the VCFS/DGS
minimally deleted interval. The cDNA encodes a protein of 1638 amino acids.
CLTD shares significant homology, but is not identical to the ubiquitously
expressed clathrin heavy chain gene. The CLTD gene also shows a unique
pattern of expression, having its maximal level of expression in skeletal
muscle. Velopharyngeal insufficiency and muscle weakness are common
features of VCFS patients. Based on the location and expression pattern of
CLTD, we suggest hemizygosity at this locus may play a role in the etiology
of one of the VCFS-associated phenotypes.
相似文献
94.
Reflections of efferent activity in rotational responses of chinchilla vestibular afferents 总被引:4,自引:0,他引:4
To study presumed efferent-mediated responses, we determined if afferents responded to head rotations that stimulated semicircular canals other than the organ being innervated. To minimize stimulation of an afferent's own canal, its plane was placed nearly orthogonal to the rotation plane. Otolith units were tested in a horizontal head position with the ear placed near the rotation axis to minimize linear forces. Under these circumstances, angular-velocity trapezoids (2-s ramps, 2-s plateau) evoked excitatory responses for both rotation directions. These type III responses were considerably larger in decerebrate than in anesthetized preparations. In addition to their being exclusively excitatory, the responses resembled those obtained with electrical stimulation of efferent pathways in including per-stimulus and more prolonged post-stimulus components and in being larger in irregularly discharging than in regularly discharging units. Responses, which were not seen for rotations <80 degrees/s, grew as velocity increased between 80 and 500 degrees/s but were seldom larger than 20 spikes/s. Complete section of the VIIIth nerve abolished type III responses, leaving conventional afferent responses intact. To study the separate contributions of canals on the two sides, responses were compared when the labyrinths were intact and when the ipsilateral or contralateral horizontal canal was mechanically inactivated. Both sides contributed to the efferent-mediated responses. That afferents could be influenced from the contralateral labyrinth was confirmed with the use of unilateral galvanic currents. Following inactivation, excitatory responses were produced by rotations exciting or inhibiting the intact horizontal canal with the responses resulting from excitatory rotations being much larger. Such a response asymmetry is consistent with a semicircular-canal origin for the type III responses. A similar asymmetry was seen in the post-stimulus responses to contralateral cathodal (excitatory) and anodal (inhibitory) galvanic currents. We conclude that the efferent system receives a sufficiently powerful vestibular input from both the ipsilateral and contralateral labyrinths to affect afferent discharge. 相似文献
95.
Mika Shapira Rootman Yael Goldberg Rony Cohen Nesia Kropach Inbal Keidar Rivka Friedland Gad Dotan Osnat Konen Helen Toledano 《Clinical genetics》2020,97(2):296-304
Constitutional mismatch repair deficiency is a rare cancer predisposition syndrome caused by biallelic mutations in one of the four mismatch repair genes. Patients are predisposed to various tumors including hematological malignancies, brain tumors and colorectal carcinomas. Phenotypic overlap with Neurofibromatosis-1 is well known, with most patients presenting with café-au-lait macules. Other common features include axillary and/or inguinal freckling and intracranial MRI foci of high T2W/FLAIR signal intensity similar to the typical FASI seen in Neurofibromatosis-1. In this cohort of eight patients with constitutional mismatch repair deficiency we describe overlapping phenotypical features with Tuberous Sclerosis complex. In addition to “ash-leaf like” hypomelanotic macules (five patients), we detected intracranial tuber-like lesions (three patients), renal cysts (three patients) and renal angiomyolipomas (two patients). All our patients also had Neurofibromatosis-1 like features, mainly café-au-lait macules. This study suggests that features of Tuberous sclerosis especially when overlapping with those of Neurofibromatosis 1 or malignancies atypical for these syndromes should raise the possibility of constitutional mismatch repair deficiency. Correct diagnosis is essential for appropriate genetic counseling and pre-emptive cancer surveillance. 相似文献
96.
Bedaiwy MA Goldberg JM Falcone T Singh M Nelson D Azab H Wang X Sharma R 《Human reproduction (Oxford, England)》2002,17(3):601-604
BACKGROUND: Oxidative stress mechanisms are involved in the pathophysiology of many reproductive disorders. The objective of this study was to characterize oxidative stress parameters in hydrosalpingeal fluid (HSF) and examine their possible role in early embryo development. METHODS AND RESULTS: HSF was aspirated at laparoscopic salpingectomy in 11 infertile women. Reactive oxygen species (ROS), total (non-enzymatic) antioxidant capacity (TAC) and lipid peroxidation (LPO) were assayed. Two-cell mouse embryos were incubated with 25, 50 or 75% HSF and the blastocyst development rate was observed. ROS was detected in five of 11 (45%) HSF samples with a mean of 4.2 x 10(4) c.p.m. LPO was detected in all samples at a mean (+/- SD) value of 5575.4 +/- 6091.9 micromol/l malonaldehyde. The mean blastocyst development rate at 25, 5+/- 0 and 75% HSF and in the control group was 88.9 +/- 9.4, 65.7 +/- 19.1, 45.7 +/- 5.7 and 96.7% respectively (P < 0.0001). The blastocyst development rate was positively correlated to ROS concentrations (P < 0.02) but was not significantly related to LPO. CONCLUSIONS: The blastocyst development rate decreased with increasing concentrations of HSF. For the first time, the presence of ROS, LPO and TAC activity in human HSF was characterized. A possible role of oxidative stress in the embryotoxicity of HSF is suggested. 相似文献
97.
Life events and depression in a community sample of siblings 总被引:4,自引:0,他引:4
Rijsdijk FV Sham PC Sterne A Purcell S McGuffin P Farmer A Goldberg D Mann A Cherny SS Webster M Ball D Eley TC Plomin R 《Psychological medicine》2001,31(3):401-410
BACKGROUND: The overall aim of the GENESiS project is to identify quantitative trait loci (QTLs) for anxiety/depression, and to examine the interaction between these loci and psychosocial adversity. Here we present life-events data with the aim of clarifying: (i) the aetiology of life events as inferred from sibling correlations; (ii) the relationship between life events and measures of anxiety and depression, as well as neuroticism; and (iii) the interaction between life events and neuroticism on anxiety/depression indices. METHODS: We assessed the occurrence of one network and three personal life-event categories and multiple indices of anxiety/depression including General Health Questionnaire, Anhedonic Depression, Anxious Arousal and Neuroticism in a large community-based sample of2150 sib pairs, 410 trios and 81 quads. Liability threshold models and raw ordinal maximum likelihood were used to estimate within-individual and between-sibling correlations of life events. The relationship between life events and indices of emotional states and personality were assessed by multiple linear regression and canonical correlations. RESULTS: Life events showed sibling correlations of 0-37 for network events and between 0-10 and 0.19 for personal events. Adverse life events were related to anxiety and depression and, to a less extent, neuroticism. Trait-vulnerability (as indexed by co-sib's neuroticism, anxiety and depression) accounted for 11% and life events for 3% of the variance in emotional states. There were no interaction effects. CONCLUSIONS: Life events show moderate familiality and are significantly related to symptoms of anxiety and depression in the community. Appropriate modelling of life events in linkage and association analyses should help to identify QTLs for depression and anxiety. 相似文献
98.
The activation of macrophages for antimicrobial responses is a multistage event involving numerous intracellular signalling cascades that makes possible target cell destruction by these effector cells. This study examined the effects of different potassium channel inhibitors and activators on the NO production of murine macrophage-like cell lines P388D.1 and B10-4(S). We found that the potassium channel inhibitors tetraethylammonium, 4-aminopyridine, and quinine caused dose-dependent reductions in the NO production of macrophages, and that the potassium channel activator, minoxidol, caused a dose-dependent enhancement of NO production. The inhibition of NO production was due to involvement of potassium channels in the priming stage of macrophage activation, since pretreatment with the priming agent interferon-gamma partially restored the NO response of the macrophages. The results of this study demonstrate a link between potassium channel activity and the activation of anitimicrobial functions of murine macrophages. 相似文献
99.
Safety of cryopreservation straws for human gametes or embryos: a study with human immunodeficiency virus-1 under cryopreservation conditions 总被引:3,自引:0,他引:3
100.